Merging upstream version 6.10.3.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

72 files changed, 2275 insertions, 1574 deletions

diff --git a/drivers/tty/serial/8250/8250.h b/drivers/tty/serial/8250/8250.h
index 1aa3e55c8b..6a7b286f6f 100644
--- a/drivers/tty/serial/8250/8250.h
+++ b/drivers/tty/serial/8250/8250.h
@@ -293,9 +293,6 @@ static inline int serial8250_in_MCR(struct uart_8250_port *up)
 	return mctrl;
 }
 
-bool alpha_jensen(void);
-void alpha_jensen_set_mctrl(struct uart_port *port, unsigned int mctrl);
-
 #ifdef CONFIG_SERIAL_8250_PNP
 int serial8250_pnp_init(void);
 void serial8250_pnp_exit(void);
diff --git a/drivers/tty/serial/8250/8250_alpha.c b/drivers/tty/serial/8250/8250_alpha.c
deleted file mode 100644
index 58e70328aa..0000000000
--- a/drivers/tty/serial/8250/8250_alpha.c
+++ /dev/null
@@ -1,21 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0+
-
-#include <asm/machvec.h>
-#include "8250.h"
-
-bool alpha_jensen(void)
-{
-	return !strcmp(alpha_mv.vector_name, "Jensen");
-}
-
-void alpha_jensen_set_mctrl(struct uart_port *port, unsigned int mctrl)
-{
-	/*
-	 * Digital did something really horribly wrong with the OUT1 and OUT2
-	 * lines on Alpha Jensen.  The failure mode is that if either is
-	 * cleared, the machine locks up with endless interrupts.
-	 */
-	mctrl |= TIOCM_OUT1 | TIOCM_OUT2;
-
-	serial8250_do_set_mctrl(port, mctrl);
-}
diff --git a/drivers/tty/serial/8250/8250_bcm7271.c b/drivers/tty/serial/8250/8250_bcm7271.c
index 61d81b11f6..2569ca6922 100644
--- a/drivers/tty/serial/8250/8250_bcm7271.c
+++ b/drivers/tty/serial/8250/8250_bcm7271.c
@@ -413,20 +413,18 @@ static int stop_tx_dma(struct uart_8250_port *p)
 static int brcmuart_tx_dma(struct uart_8250_port *p)
 {
 	struct brcmuart_priv *priv = p->port.private_data;
-	struct circ_buf *xmit = &p->port.state->xmit;
+	struct tty_port *tport = &p->port.state->port;
 	u32 tx_size;
 
 	if (uart_tx_stopped(&p->port) || priv->tx_running ||
-		uart_circ_empty(xmit)) {
+		kfifo_is_empty(&tport->xmit_fifo)) {
 		return 0;
 	}
-	tx_size = CIRC_CNT_TO_END(xmit->head, xmit->tail, UART_XMIT_SIZE);
 
 	priv->dma.tx_err = 0;
-	memcpy(priv->tx_buf, &xmit->buf[xmit->tail], tx_size);
-	uart_xmit_advance(&p->port, tx_size);
+	tx_size = uart_fifo_out(&p->port, priv->tx_buf, UART_XMIT_SIZE);
 
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+	if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)
 		uart_write_wakeup(&p->port);
 
 	udma_writel(priv, REGS_DMA_TX, UDMA_TX_TRANSFER_LEN, tx_size);
@@ -540,7 +538,7 @@ static void brcmuart_tx_isr(struct uart_port *up, u32 isr)
 	struct brcmuart_priv *priv = up->private_data;
 	struct device *dev = up->dev;
 	struct uart_8250_port *port_8250 = up_to_u8250p(up);
-	struct circ_buf	*xmit = &port_8250->port.state->xmit;
+	struct tty_port *tport = &port_8250->port.state->port;
 
 	if (isr & UDMA_INTR_TX_ABORT) {
 		if (priv->tx_running)
@@ -548,7 +546,7 @@ static void brcmuart_tx_isr(struct uart_port *up, u32 isr)
 		return;
 	}
 	priv->tx_running = false;
-	if (!uart_circ_empty(xmit) && !uart_tx_stopped(up))
+	if (!kfifo_is_empty(&tport->xmit_fifo) && !uart_tx_stopped(up))
 		brcmuart_tx_dma(port_8250);
 }
 
diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c
index b62ad90067..b0adafc447 100644
--- a/drivers/tty/serial/8250/8250_core.c
+++ b/drivers/tty/serial/8250/8250_core.c
@@ -280,7 +280,8 @@ static void serial8250_backup_timeout(struct timer_list *t)
 	 */
 	lsr = serial_lsr_in(up);
 	if ((iir & UART_IIR_NO_INT) && (up->ier & UART_IER_THRI) &&
-	    (!uart_circ_empty(&up->port.state->xmit) || up->port.x_char) &&
+	    (!kfifo_is_empty(&up->port.state->port.xmit_fifo) ||
+	     up->port.x_char) &&
 	    (lsr & UART_LSR_THRE)) {
 		iir &= ~(UART_IIR_ID | UART_IIR_NO_INT);
 		iir |= UART_IIR_THRI;
@@ -508,10 +509,6 @@ static struct uart_8250_port *serial8250_setup_port(int index)
 
 	up->ops = &univ8250_driver_ops;
 
-	if (IS_ENABLED(CONFIG_ALPHA_JENSEN) ||
-	    (IS_ENABLED(CONFIG_ALPHA_GENERIC) && alpha_jensen()))
-		up->port.set_mctrl = alpha_jensen_set_mctrl;
-
 	serial8250_set_defaults(up);
 
 	return up;
diff --git a/drivers/tty/serial/8250/8250_dma.c b/drivers/tty/serial/8250/8250_dma.c
index 8b30ca8fdd..8a353e3cc3 100644
--- a/drivers/tty/serial/8250/8250_dma.c
+++ b/drivers/tty/serial/8250/8250_dma.c
@@ -15,7 +15,7 @@ static void __dma_tx_complete(void *param)
 {
 	struct uart_8250_port	*p = param;
 	struct uart_8250_dma	*dma = p->dma;
-	struct circ_buf		*xmit = &p->port.state->xmit;
+	struct tty_port		*tport = &p->port.state->port;
 	unsigned long	flags;
 	int		ret;
 
@@ -28,7 +28,7 @@ static void __dma_tx_complete(void *param)
 
 	uart_xmit_advance(&p->port, dma->tx_size);
 
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+	if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)
 		uart_write_wakeup(&p->port);
 
 	ret = serial8250_tx_dma(p);
@@ -86,9 +86,10 @@ static void dma_rx_complete(void *param)
 int serial8250_tx_dma(struct uart_8250_port *p)
 {
 	struct uart_8250_dma		*dma = p->dma;
-	struct circ_buf			*xmit = &p->port.state->xmit;
+	struct tty_port			*tport = &p->port.state->port;
 	struct dma_async_tx_descriptor	*desc;
 	struct uart_port		*up = &p->port;
+	struct scatterlist sg;
 	int ret;
 
 	if (dma->tx_running) {
@@ -102,19 +103,27 @@ int serial8250_tx_dma(struct uart_8250_port *p)
 		uart_xchar_out(up, UART_TX);
 	}
 
-	if (uart_tx_stopped(&p->port) || uart_circ_empty(xmit)) {
+	if (uart_tx_stopped(&p->port) || kfifo_is_empty(&tport->xmit_fifo)) {
 		/* We have been called from __dma_tx_complete() */
 		return 0;
 	}
 
-	dma->tx_size = CIRC_CNT_TO_END(xmit->head, xmit->tail, UART_XMIT_SIZE);
-
 	serial8250_do_prepare_tx_dma(p);
 
-	desc = dmaengine_prep_slave_single(dma->txchan,
-					   dma->tx_addr + xmit->tail,
-					   dma->tx_size, DMA_MEM_TO_DEV,
-					   DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
+	sg_init_table(&sg, 1);
+	/* kfifo can do more than one sg, we don't (quite yet) */
+	ret = kfifo_dma_out_prepare_mapped(&tport->xmit_fifo, &sg, 1,
+					   UART_XMIT_SIZE, dma->tx_addr);
+
+	/* we already checked empty fifo above, so there should be something */
+	if (WARN_ON_ONCE(ret != 1))
+		return 0;
+
+	dma->tx_size = sg_dma_len(&sg);
+
+	desc = dmaengine_prep_slave_sg(dma->txchan, &sg, 1,
+				       DMA_MEM_TO_DEV,
+				       DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
 	if (!desc) {
 		ret = -EBUSY;
 		goto err;
@@ -253,7 +262,7 @@ int serial8250_request_dma(struct uart_8250_port *p)
 
 	/* TX buffer */
 	dma->tx_addr = dma_map_single(dma->txchan->device->dev,
-					p->port.state->xmit.buf,
+					p->port.state->port.xmit_buf,
 					UART_XMIT_SIZE,
 					DMA_TO_DEVICE);
 	if (dma_mapping_error(dma->txchan->device->dev, dma->tx_addr)) {
diff --git a/drivers/tty/serial/8250/8250_dw.c b/drivers/tty/serial/8250/8250_dw.c
index a58890fd53..fb809e32c6 100644
--- a/drivers/tty/serial/8250/8250_dw.c
+++ b/drivers/tty/serial/8250/8250_dw.c
@@ -128,14 +128,18 @@ static void dw8250_force_idle(struct uart_port *p)
 	(void)p->serial_in(p, UART_RX);
 }
 
-static void dw8250_check_lcr(struct uart_port *p, int value)
+static void dw8250_check_lcr(struct uart_port *p, int offset, int value)
 {
-	void __iomem *offset = p->membase + (UART_LCR << p->regshift);
+	struct dw8250_data *d = to_dw8250_data(p->private_data);
+	void __iomem *addr = p->membase + (offset << p->regshift);
 	int tries = 1000;
 
+	if (offset != UART_LCR || d->uart_16550_compatible)
+		return;
+
 	/* Make sure LCR write wasn't ignored */
 	while (tries--) {
-		unsigned int lcr = p->serial_in(p, UART_LCR);
+		unsigned int lcr = p->serial_in(p, offset);
 
 		if ((value & ~UART_LCR_SPAR) == (lcr & ~UART_LCR_SPAR))
 			return;
@@ -144,15 +148,15 @@ static void dw8250_check_lcr(struct uart_port *p, int value)
 
 #ifdef CONFIG_64BIT
 		if (p->type == PORT_OCTEON)
-			__raw_writeq(value & 0xff, offset);
+			__raw_writeq(value & 0xff, addr);
 		else
 #endif
 		if (p->iotype == UPIO_MEM32)
-			writel(value, offset);
+			writel(value, addr);
 		else if (p->iotype == UPIO_MEM32BE)
-			iowrite32be(value, offset);
+			iowrite32be(value, addr);
 		else
-			writeb(value, offset);
+			writeb(value, addr);
 	}
 	/*
 	 * FIXME: this deadlocks if port->lock is already held
@@ -186,12 +190,8 @@ static void dw8250_tx_wait_empty(struct uart_port *p)
 
 static void dw8250_serial_out(struct uart_port *p, int offset, int value)
 {
-	struct dw8250_data *d = to_dw8250_data(p->private_data);
-
 	writeb(value, p->membase + (offset << p->regshift));
-
-	if (offset == UART_LCR && !d->uart_16550_compatible)
-		dw8250_check_lcr(p, value);
+	dw8250_check_lcr(p, offset, value);
 }
 
 static void dw8250_serial_out38x(struct uart_port *p, int offset, int value)
@@ -213,35 +213,26 @@ static unsigned int dw8250_serial_in(struct uart_port *p, int offset)
 #ifdef CONFIG_64BIT
 static unsigned int dw8250_serial_inq(struct uart_port *p, int offset)
 {
-	unsigned int value;
-
-	value = (u8)__raw_readq(p->membase + (offset << p->regshift));
+	u8 value = __raw_readq(p->membase + (offset << p->regshift));
 
 	return dw8250_modify_msr(p, offset, value);
 }
 
 static void dw8250_serial_outq(struct uart_port *p, int offset, int value)
 {
-	struct dw8250_data *d = to_dw8250_data(p->private_data);
-
 	value &= 0xff;
 	__raw_writeq(value, p->membase + (offset << p->regshift));
 	/* Read back to ensure register write ordering. */
 	__raw_readq(p->membase + (UART_LCR << p->regshift));
 
-	if (offset == UART_LCR && !d->uart_16550_compatible)
-		dw8250_check_lcr(p, value);
+	dw8250_check_lcr(p, offset, value);
 }
 #endif /* CONFIG_64BIT */
 
 static void dw8250_serial_out32(struct uart_port *p, int offset, int value)
 {
-	struct dw8250_data *d = to_dw8250_data(p->private_data);
-
 	writel(value, p->membase + (offset << p->regshift));
-
-	if (offset == UART_LCR && !d->uart_16550_compatible)
-		dw8250_check_lcr(p, value);
+	dw8250_check_lcr(p, offset, value);
 }
 
 static unsigned int dw8250_serial_in32(struct uart_port *p, int offset)
@@ -253,12 +244,8 @@ static unsigned int dw8250_serial_in32(struct uart_port *p, int offset)
 
 static void dw8250_serial_out32be(struct uart_port *p, int offset, int value)
 {
-	struct dw8250_data *d = to_dw8250_data(p->private_data);
-
 	iowrite32be(value, p->membase + (offset << p->regshift));
-
-	if (offset == UART_LCR && !d->uart_16550_compatible)
-		dw8250_check_lcr(p, value);
+	dw8250_check_lcr(p, offset, value);
 }
 
 static unsigned int dw8250_serial_in32be(struct uart_port *p, int offset)
diff --git a/drivers/tty/serial/8250/8250_exar.c b/drivers/tty/serial/8250/8250_exar.c
index 4d1e07343d..616128254b 100644
--- a/drivers/tty/serial/8250/8250_exar.c
+++ b/drivers/tty/serial/8250/8250_exar.c
@@ -6,6 +6,7 @@
  *
  *  Copyright (C) 2017 Sudip Mukherjee, All Rights Reserved.
  */
+#include <linux/bitfield.h>
 #include <linux/bits.h>
 #include <linux/delay.h>
 #include <linux/device.h>
@@ -128,12 +129,25 @@
 #define UART_EXAR_DLD			0x02 /* Divisor Fractional */
 #define UART_EXAR_DLD_485_POLARITY	0x80 /* RS-485 Enable Signal Polarity */
 
+/* EEPROM registers */
+#define UART_EXAR_REGB			0x8e
+#define UART_EXAR_REGB_EECK		BIT(4)
+#define UART_EXAR_REGB_EECS		BIT(5)
+#define UART_EXAR_REGB_EEDI		BIT(6)
+#define UART_EXAR_REGB_EEDO		BIT(7)
+#define UART_EXAR_REGB_EE_ADDR_SIZE	6
+#define UART_EXAR_REGB_EE_DATA_SIZE	16
+
+#define UART_EXAR_XR17C15X_PORT_OFFSET	0x200
+#define UART_EXAR_XR17V25X_PORT_OFFSET	0x200
+#define UART_EXAR_XR17V35X_PORT_OFFSET	0x400
+
 /*
  * IOT2040 MPIO wiring semantics:
  *
  * MPIO		Port	Function
  * ----		----	--------
- * 0		2 	Mode bit 0
+ * 0		2	Mode bit 0
  * 1		2	Mode bit 1
  * 2		2	Terminate bus
  * 3		-	<reserved>
@@ -163,38 +177,300 @@
 #define IOT2040_UARTS_ENABLE		0x03
 #define IOT2040_UARTS_GPIO_HI_MODE	0xF8	/* enable & LED as outputs */
 
+/* CTI EEPROM offsets */
+#define CTI_EE_OFF_XR17C15X_OSC_FREQ	0x04  /* 2 words */
+#define CTI_EE_OFF_XR17V25X_OSC_FREQ	0x08  /* 2 words */
+#define CTI_EE_OFF_XR17C15X_PART_NUM	0x0A  /* 4 words */
+#define CTI_EE_OFF_XR17V25X_PART_NUM	0x0E  /* 4 words */
+#define CTI_EE_OFF_XR17C15X_SERIAL_NUM	0x0E  /* 1 word */
+#define CTI_EE_OFF_XR17V25X_SERIAL_NUM	0x12  /* 1 word */
+#define CTI_EE_OFF_XR17V35X_SERIAL_NUM	0x11  /* 2 word */
+#define CTI_EE_OFF_XR17V35X_BRD_FLAGS	0x13  /* 1 word */
+#define CTI_EE_OFF_XR17V35X_PORT_FLAGS	0x14  /* 1 word */
+
+#define CTI_EE_MASK_PORT_FLAGS_TYPE	GENMASK(7, 0)
+#define CTI_EE_MASK_OSC_FREQ_LOWER	GENMASK(15, 0)
+#define CTI_EE_MASK_OSC_FREQ_UPPER	GENMASK(31, 16)
+
+#define CTI_FPGA_RS485_IO_REG		0x2008
+#define CTI_FPGA_CFG_INT_EN_REG		0x48
+#define CTI_FPGA_CFG_INT_EN_EXT_BIT	BIT(15) /* External int enable bit */
+
+#define CTI_DEFAULT_PCI_OSC_FREQ	29491200
+#define CTI_DEFAULT_PCIE_OSC_FREQ	125000000
+#define CTI_DEFAULT_FPGA_OSC_FREQ	33333333
+
+/*
+ * CTI Serial port line types. These match the values stored in the first
+ * nibble of the CTI EEPROM port_flags word.
+ */
+enum cti_port_type {
+	CTI_PORT_TYPE_NONE = 0,
+	CTI_PORT_TYPE_RS232,            // RS232 ONLY
+	CTI_PORT_TYPE_RS422_485,        // RS422/RS485 ONLY
+	CTI_PORT_TYPE_RS232_422_485_HW, // RS232/422/485 HW ONLY Switchable
+	CTI_PORT_TYPE_RS232_422_485_SW, // RS232/422/485 SW ONLY Switchable
+	CTI_PORT_TYPE_RS232_422_485_4B, // RS232/422/485 HW/SW (4bit ex. BCG004)
+	CTI_PORT_TYPE_RS232_422_485_2B, // RS232/422/485 HW/SW (2bit ex. BBG008)
+	CTI_PORT_TYPE_MAX,
+};
+
+#define CTI_PORT_TYPE_VALID(_port_type) \
+	(((_port_type) > CTI_PORT_TYPE_NONE) && \
+	((_port_type) < CTI_PORT_TYPE_MAX))
+
+#define CTI_PORT_TYPE_RS485(_port_type) \
+	(((_port_type) > CTI_PORT_TYPE_RS232) && \
+	((_port_type) < CTI_PORT_TYPE_MAX))
+
 struct exar8250;
 
 struct exar8250_platform {
 	int (*rs485_config)(struct uart_port *port, struct ktermios *termios,
 			    struct serial_rs485 *rs485);
 	const struct serial_rs485 *rs485_supported;
-	int (*register_gpio)(struct pci_dev *, struct uart_8250_port *);
-	void (*unregister_gpio)(struct uart_8250_port *);
+	int (*register_gpio)(struct pci_dev *pcidev, struct uart_8250_port *port);
+	void (*unregister_gpio)(struct uart_8250_port *port);
 };
 
 /**
  * struct exar8250_board - board information
  * @num_ports: number of serial ports
  * @reg_shift: describes UART register mapping in PCI memory
- * @setup: quirk run at ->probe() stage
+ * @setup: quirk run at ->probe() stage for each port
  * @exit: quirk run at ->remove() stage
  */
 struct exar8250_board {
 	unsigned int num_ports;
 	unsigned int reg_shift;
-	int	(*setup)(struct exar8250 *, struct pci_dev *,
-			 struct uart_8250_port *, int);
+	int	(*setup)(struct exar8250 *priv, struct pci_dev *pcidev,
+			 struct uart_8250_port *port, int idx);
 	void	(*exit)(struct pci_dev *pcidev);
 };
 
 struct exar8250 {
 	unsigned int		nr;
+	unsigned int		osc_freq;
 	struct exar8250_board	*board;
 	void __iomem		*virt;
 	int			line[];
 };
 
+static inline void exar_write_reg(struct exar8250 *priv,
+				unsigned int reg, u8 value)
+{
+	writeb(value, priv->virt + reg);
+}
+
+static inline u8 exar_read_reg(struct exar8250 *priv, unsigned int reg)
+{
+	return readb(priv->virt + reg);
+}
+
+static inline void exar_ee_select(struct exar8250 *priv)
+{
+	// Set chip select pin high to enable EEPROM reads/writes
+	exar_write_reg(priv, UART_EXAR_REGB, UART_EXAR_REGB_EECS);
+	// Min ~500ns delay needed between CS assert and EEPROM access
+	udelay(1);
+}
+
+static inline void exar_ee_deselect(struct exar8250 *priv)
+{
+	exar_write_reg(priv, UART_EXAR_REGB, 0x00);
+}
+
+static inline void exar_ee_write_bit(struct exar8250 *priv, u8 bit)
+{
+	u8 value = UART_EXAR_REGB_EECS;
+
+	if (bit)
+		value |= UART_EXAR_REGB_EEDI;
+
+	// Clock out the bit on the EEPROM interface
+	exar_write_reg(priv, UART_EXAR_REGB, value);
+	// 2us delay = ~500khz clock speed
+	udelay(2);
+
+	value |= UART_EXAR_REGB_EECK;
+
+	exar_write_reg(priv, UART_EXAR_REGB, value);
+	udelay(2);
+}
+
+static inline u8 exar_ee_read_bit(struct exar8250 *priv)
+{
+	u8 regb;
+	u8 value = UART_EXAR_REGB_EECS;
+
+	// Clock in the bit on the EEPROM interface
+	exar_write_reg(priv, UART_EXAR_REGB, value);
+	// 2us delay = ~500khz clock speed
+	udelay(2);
+
+	value |= UART_EXAR_REGB_EECK;
+
+	exar_write_reg(priv, UART_EXAR_REGB, value);
+	udelay(2);
+
+	regb = exar_read_reg(priv, UART_EXAR_REGB);
+
+	return (regb & UART_EXAR_REGB_EEDO ? 1 : 0);
+}
+
+/**
+ * exar_ee_read() - Read a word from the EEPROM
+ * @priv: Device's private structure
+ * @ee_addr: Offset of EEPROM to read word from
+ *
+ * Read a single 16bit word from an Exar UART's EEPROM.
+ * The type of the EEPROM is AT93C46D.
+ *
+ * Return: EEPROM word
+ */
+static u16 exar_ee_read(struct exar8250 *priv, u8 ee_addr)
+{
+	int i;
+	u16 data = 0;
+
+	exar_ee_select(priv);
+
+	// Send read command (opcode 110)
+	exar_ee_write_bit(priv, 1);
+	exar_ee_write_bit(priv, 1);
+	exar_ee_write_bit(priv, 0);
+
+	// Send address to read from
+	for (i = UART_EXAR_REGB_EE_ADDR_SIZE - 1; i >= 0; i--)
+		exar_ee_write_bit(priv, ee_addr & BIT(i));
+
+	// Read data 1 bit at a time starting with a dummy bit
+	for (i = UART_EXAR_REGB_EE_DATA_SIZE; i >= 0; i--) {
+		if (exar_ee_read_bit(priv))
+			data |= BIT(i);
+	}
+
+	exar_ee_deselect(priv);
+
+	return data;
+}
+
+/**
+ * exar_mpio_config_output() - Configure an Exar MPIO as an output
+ * @priv: Device's private structure
+ * @mpio_num: MPIO number/offset to configure
+ *
+ * Configure a single MPIO as an output and disable tristate. It is reccomended
+ * to set the level with exar_mpio_set_high()/exar_mpio_set_low() prior to
+ * calling this function to ensure default MPIO pin state.
+ *
+ * Return: 0 on success, negative error code on failure
+ */
+static int exar_mpio_config_output(struct exar8250 *priv,
+				unsigned int mpio_num)
+{
+	unsigned int mpio_offset;
+	u8 sel_reg; // MPIO Select register (input/output)
+	u8 tri_reg; // MPIO Tristate register
+	u8 value;
+
+	if (mpio_num < 8) {
+		sel_reg = UART_EXAR_MPIOSEL_7_0;
+		tri_reg = UART_EXAR_MPIO3T_7_0;
+		mpio_offset = mpio_num;
+	} else if (mpio_num >= 8 && mpio_num < 16) {
+		sel_reg = UART_EXAR_MPIOSEL_15_8;
+		tri_reg = UART_EXAR_MPIO3T_15_8;
+		mpio_offset = mpio_num - 8;
+	} else {
+		return -EINVAL;
+	}
+
+	// Disable MPIO pin tri-state
+	value = exar_read_reg(priv, tri_reg);
+	value &= ~BIT(mpio_offset);
+	exar_write_reg(priv, tri_reg, value);
+
+	value = exar_read_reg(priv, sel_reg);
+	value &= ~BIT(mpio_offset);
+	exar_write_reg(priv, sel_reg, value);
+
+	return 0;
+}
+
+/**
+ * _exar_mpio_set() - Set an Exar MPIO output high or low
+ * @priv: Device's private structure
+ * @mpio_num: MPIO number/offset to set
+ * @high: Set MPIO high if true, low if false
+ *
+ * Set a single MPIO high or low. exar_mpio_config_output() must also be called
+ * to configure the pin as an output.
+ *
+ * Return: 0 on success, negative error code on failure
+ */
+static int _exar_mpio_set(struct exar8250 *priv,
+			unsigned int mpio_num, bool high)
+{
+	unsigned int mpio_offset;
+	u8 lvl_reg;
+	u8 value;
+
+	if (mpio_num < 8) {
+		lvl_reg = UART_EXAR_MPIOLVL_7_0;
+		mpio_offset = mpio_num;
+	} else if (mpio_num >= 8 && mpio_num < 16) {
+		lvl_reg = UART_EXAR_MPIOLVL_15_8;
+		mpio_offset = mpio_num - 8;
+	} else {
+		return -EINVAL;
+	}
+
+	value = exar_read_reg(priv, lvl_reg);
+	if (high)
+		value |= BIT(mpio_offset);
+	else
+		value &= ~BIT(mpio_offset);
+	exar_write_reg(priv, lvl_reg, value);
+
+	return 0;
+}
+
+static int exar_mpio_set_low(struct exar8250 *priv, unsigned int mpio_num)
+{
+	return _exar_mpio_set(priv, mpio_num, false);
+}
+
+static int exar_mpio_set_high(struct exar8250 *priv, unsigned int mpio_num)
+{
+	return _exar_mpio_set(priv, mpio_num, true);
+}
+
+static int generic_rs485_config(struct uart_port *port, struct ktermios *termios,
+				struct serial_rs485 *rs485)
+{
+	bool is_rs485 = !!(rs485->flags & SER_RS485_ENABLED);
+	u8 __iomem *p = port->membase;
+	u8 value;
+
+	value = readb(p + UART_EXAR_FCTR);
+	if (is_rs485)
+		value |= UART_FCTR_EXAR_485;
+	else
+		value &= ~UART_FCTR_EXAR_485;
+
+	writeb(value, p + UART_EXAR_FCTR);
+
+	if (is_rs485)
+		writeb(UART_EXAR_RS485_DLY(4), p + UART_MSR);
+
+	return 0;
+}
+
+static const struct serial_rs485 generic_rs485_supported = {
+	.flags = SER_RS485_ENABLED | SER_RS485_RTS_ON_SEND,
+};
+
 static void exar_pm(struct uart_port *port, unsigned int state, unsigned int old)
 {
 	/*
@@ -256,7 +532,7 @@ static void exar_shutdown(struct uart_port *port)
 {
 	bool tx_complete = false;
 	struct uart_8250_port *up = up_to_u8250p(port);
-	struct circ_buf *xmit = &port->state->xmit;
+	struct tty_port *tport = &port->state->port;
 	int i = 0;
 	u16 lsr;
 
@@ -267,7 +543,8 @@ static void exar_shutdown(struct uart_port *port)
 		else
 			tx_complete = false;
 		usleep_range(1000, 1100);
-	} while (!uart_circ_empty(xmit) && !tx_complete && i++ < 1000);
+	} while (!kfifo_is_empty(&tport->xmit_fifo) &&
+			!tx_complete && i++ < 1000);
 
 	serial8250_do_shutdown(port);
 }
@@ -331,41 +608,546 @@ pci_fastcom335_setup(struct exar8250 *priv, struct pci_dev *pcidev,
 	writeb(32, p + UART_EXAR_TXTRG);
 	writeb(32, p + UART_EXAR_RXTRG);
 
+	/* Skip the initial (per device) setup */
+	if (idx)
+		return 0;
+
 	/*
 	 * Setup Multipurpose Input/Output pins.
 	 */
+	switch (pcidev->device) {
+	case PCI_DEVICE_ID_COMMTECH_4222PCI335:
+	case PCI_DEVICE_ID_COMMTECH_4224PCI335:
+		writeb(0x78, p + UART_EXAR_MPIOLVL_7_0);
+		writeb(0x00, p + UART_EXAR_MPIOINV_7_0);
+		writeb(0x00, p + UART_EXAR_MPIOSEL_7_0);
+		break;
+	case PCI_DEVICE_ID_COMMTECH_2324PCI335:
+	case PCI_DEVICE_ID_COMMTECH_2328PCI335:
+		writeb(0x00, p + UART_EXAR_MPIOLVL_7_0);
+		writeb(0xc0, p + UART_EXAR_MPIOINV_7_0);
+		writeb(0xc0, p + UART_EXAR_MPIOSEL_7_0);
+		break;
+	default:
+		break;
+	}
+	writeb(0x00, p + UART_EXAR_MPIOINT_7_0);
+	writeb(0x00, p + UART_EXAR_MPIO3T_7_0);
+	writeb(0x00, p + UART_EXAR_MPIOOD_7_0);
+
+	return 0;
+}
+
+/**
+ * cti_tristate_disable() - Disable RS485 transciever tristate
+ * @priv: Device's private structure
+ * @port_num: Port number to set tristate off
+ *
+ * Most RS485 capable cards have a power on tristate jumper/switch that ensures
+ * the RS422/RS485 transceiver does not drive a multi-drop RS485 bus when it is
+ * not the master. When this jumper is installed the user must set the RS485
+ * mode to Full or Half duplex to disable tristate prior to using the port.
+ *
+ * Some Exar UARTs have an auto-tristate feature while others require setting
+ * an MPIO to disable the tristate.
+ *
+ * Return: 0 on success, negative error code on failure
+ */
+static int cti_tristate_disable(struct exar8250 *priv, unsigned int port_num)
+{
+	int ret;
+
+	ret = exar_mpio_set_high(priv, port_num);
+	if (ret)
+		return ret;
+
+	return exar_mpio_config_output(priv, port_num);
+}
+
+/**
+ * cti_plx_int_enable() - Enable UART interrupts to PLX bridge
+ * @priv: Device's private structure
+ *
+ * Some older CTI cards require MPIO_0 to be set low to enable the
+ * interrupts from the UART to the PLX PCI->PCIe bridge.
+ *
+ * Return: 0 on success, negative error code on failure
+ */
+static int cti_plx_int_enable(struct exar8250 *priv)
+{
+	int ret;
+
+	ret = exar_mpio_set_low(priv, 0);
+	if (ret)
+		return ret;
+
+	return exar_mpio_config_output(priv, 0);
+}
+
+/**
+ * cti_read_osc_freq() - Read the UART oscillator frequency from EEPROM
+ * @priv: Device's private structure
+ * @eeprom_offset: Offset where the oscillator frequency is stored
+ *
+ * CTI XR17x15X and XR17V25X cards have the serial boards oscillator frequency
+ * stored in the EEPROM. FPGA and XR17V35X based cards use the PCI/PCIe clock.
+ *
+ * Return: frequency on success, negative error code on failure
+ */
+static int cti_read_osc_freq(struct exar8250 *priv, u8 eeprom_offset)
+{
+	u16 lower_word;
+	u16 upper_word;
+
+	lower_word = exar_ee_read(priv, eeprom_offset);
+	// Check if EEPROM word was blank
+	if (lower_word == 0xFFFF)
+		return -EIO;
+
+	upper_word = exar_ee_read(priv, (eeprom_offset + 1));
+	if (upper_word == 0xFFFF)
+		return -EIO;
+
+	return FIELD_PREP(CTI_EE_MASK_OSC_FREQ_LOWER, lower_word) |
+	       FIELD_PREP(CTI_EE_MASK_OSC_FREQ_UPPER, upper_word);
+}
+
+/**
+ * cti_get_port_type_xr17c15x_xr17v25x() - Get port type of xr17c15x/xr17v25x
+ * @priv: Device's private structure
+ * @pcidev: Pointer to the PCI device for this port
+ * @port_num: Port to get type of
+ *
+ * CTI xr17c15x and xr17v25x based cards port types are based on PCI IDs.
+ *
+ * Return: port type on success, CTI_PORT_TYPE_NONE on failure
+ */
+static enum cti_port_type cti_get_port_type_xr17c15x_xr17v25x(struct exar8250 *priv,
+							struct pci_dev *pcidev,
+							unsigned int port_num)
+{
+	switch (pcidev->subsystem_device) {
+	// RS232 only cards
+	case PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_2_232:
+	case PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_4_232:
+	case PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_8_232:
+	case PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_8_SP_232:
+	case PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_8_SP_232_NS:
+	case PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_8_XPRS_LP_232:
+	case PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_8_XPRS_LP_232_NS:
+		return CTI_PORT_TYPE_RS232;
+	// 1x RS232, 1x RS422/RS485
+	case PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_1_1:
+		return (port_num == 0) ? CTI_PORT_TYPE_RS232 : CTI_PORT_TYPE_RS422_485;
+	// 2x RS232, 2x RS422/RS485
+	case PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_2_2:
+		return (port_num < 2) ? CTI_PORT_TYPE_RS232 : CTI_PORT_TYPE_RS422_485;
+	// 4x RS232, 4x RS422/RS485
+	case PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_4_4:
+	case PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_4_4_SP:
+		return (port_num < 4) ? CTI_PORT_TYPE_RS232 : CTI_PORT_TYPE_RS422_485;
+	// RS232/RS422/RS485 HW (jumper) selectable
+	case PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_2:
+	case PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_4:
+	case PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_8:
+	case PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_2_SP_OPTO:
+	case PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_4_SP_OPTO_A:
+	case PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_4_SP_OPTO_B:
+	case PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_2_XPRS:
+	case PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_4_XPRS_A:
+	case PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_4_XPRS_B:
+	case PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_8_XPRS:
+	case PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_16_XPRS_A:
+	case PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_16_XPRS_B:
+	case PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_2_XPRS_OPTO:
+	case PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_4_XPRS_OPTO_A:
+	case PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_4_XPRS_OPTO_B:
+	case PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_8_SP:
+	case PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_2_XP_OPTO_LEFT:
+	case PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_2_XP_OPTO_RIGHT:
+	case PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_4_XP_OPTO:
+	case PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_4_4_XPRS_OPTO:
+	case PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_8_XPRS_LP:
+		return CTI_PORT_TYPE_RS232_422_485_HW;
+	// RS422/RS485 HW (jumper) selectable
+	case PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_2_485:
+	case PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_4_485:
+	case PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_8_485:
+	case PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_8_SP_485:
+	case PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_8_XPRS_LP_485:
+		return CTI_PORT_TYPE_RS422_485;
+	// 6x RS232, 2x RS422/RS485
+	case PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_6_2_SP:
+		return (port_num < 6) ? CTI_PORT_TYPE_RS232 : CTI_PORT_TYPE_RS422_485;
+	// 2x RS232, 6x RS422/RS485
+	case PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_2_6_SP:
+		return (port_num < 2) ? CTI_PORT_TYPE_RS232 : CTI_PORT_TYPE_RS422_485;
+	default:
+		dev_err(&pcidev->dev, "unknown/unsupported device\n");
+		return CTI_PORT_TYPE_NONE;
+	}
+}
+
+/**
+ * cti_get_port_type_fpga() - Get the port type of a CTI FPGA card
+ * @priv: Device's private structure
+ * @pcidev: Pointer to the PCI device for this port
+ * @port_num: Port to get type of
+ *
+ * FPGA based cards port types are based on PCI IDs.
+ *
+ * Return: port type on success, CTI_PORT_TYPE_NONE on failure
+ */
+static enum cti_port_type cti_get_port_type_fpga(struct exar8250 *priv,
+						struct pci_dev *pcidev,
+						unsigned int port_num)
+{
+	switch (pcidev->device) {
+	case PCI_DEVICE_ID_CONNECT_TECH_PCI_XR79X_12_XIG00X:
+	case PCI_DEVICE_ID_CONNECT_TECH_PCI_XR79X_12_XIG01X:
+	case PCI_DEVICE_ID_CONNECT_TECH_PCI_XR79X_16:
+		return CTI_PORT_TYPE_RS232_422_485_HW;
+	default:
+		dev_err(&pcidev->dev, "unknown/unsupported device\n");
+		return CTI_PORT_TYPE_NONE;
+	}
+}
+
+/**
+ * cti_get_port_type_xr17v35x() - Read port type from the EEPROM
+ * @priv: Device's private structure
+ * @pcidev: Pointer to the PCI device for this port
+ * @port_num: port offset
+ *
+ * CTI XR17V35X based cards have the port types stored in the EEPROM.
+ * This function reads the port type for a single port.
+ *
+ * Return: port type on success, CTI_PORT_TYPE_NONE on failure
+ */
+static enum cti_port_type cti_get_port_type_xr17v35x(struct exar8250 *priv,
+						struct pci_dev *pcidev,
+						unsigned int port_num)
+{
+	enum cti_port_type port_type;
+	u16 port_flags;
+	u8 offset;
+
+	offset = CTI_EE_OFF_XR17V35X_PORT_FLAGS + port_num;
+	port_flags = exar_ee_read(priv, offset);
+
+	port_type = FIELD_GET(CTI_EE_MASK_PORT_FLAGS_TYPE, port_flags);
+	if (CTI_PORT_TYPE_VALID(port_type))
+		return port_type;
+
+	/*
+	 * If the port type is missing the card assume it is a
+	 * RS232/RS422/RS485 card to be safe.
+	 *
+	 * There is one known board (BEG013) that only has 3 of 4 port types
+	 * written to the EEPROM so this acts as a work around.
+	 */
+	dev_warn(&pcidev->dev, "failed to get port %d type from EEPROM\n", port_num);
+
+	return CTI_PORT_TYPE_RS232_422_485_HW;
+}
+
+static int cti_rs485_config_mpio_tristate(struct uart_port *port,
+					struct ktermios *termios,
+					struct serial_rs485 *rs485)
+{
+	struct exar8250 *priv = (struct exar8250 *)port->private_data;
+	int ret;
+
+	ret = generic_rs485_config(port, termios, rs485);
+	if (ret)
+		return ret;
+
+	// Disable power-on RS485 tri-state via MPIO
+	return cti_tristate_disable(priv, port->port_id);
+}
+
+static void cti_board_init_osc_freq(struct exar8250 *priv, struct pci_dev *pcidev, u8 eeprom_offset)
+{
+	int osc_freq;
+
+	osc_freq = cti_read_osc_freq(priv, eeprom_offset);
+	if (osc_freq <= 0) {
+		dev_warn(&pcidev->dev, "failed to read OSC freq from EEPROM, using default\n");
+		osc_freq = CTI_DEFAULT_PCI_OSC_FREQ;
+	}
+
+	priv->osc_freq = osc_freq;
+}
+
+static int cti_port_setup_common(struct exar8250 *priv,
+				struct pci_dev *pcidev,
+				int idx, unsigned int offset,
+				struct uart_8250_port *port)
+{
+	int ret;
+
+	port->port.port_id = idx;
+	port->port.uartclk = priv->osc_freq;
+
+	ret = serial8250_pci_setup_port(pcidev, port, 0, offset, 0);
+	if (ret)
+		return ret;
+
+	port->port.private_data = (void *)priv;
+	port->port.pm = exar_pm;
+	port->port.shutdown = exar_shutdown;
+
+	return 0;
+}
+
+static int cti_board_init_fpga(struct exar8250 *priv, struct pci_dev *pcidev)
+{
+	int ret;
+	u16 cfg_val;
+
+	// FPGA OSC is fixed to the 33MHz PCI clock
+	priv->osc_freq = CTI_DEFAULT_FPGA_OSC_FREQ;
+
+	// Enable external interrupts in special cfg space register
+	ret = pci_read_config_word(pcidev, CTI_FPGA_CFG_INT_EN_REG, &cfg_val);
+	if (ret)
+		return pcibios_err_to_errno(ret);
+
+	cfg_val |= CTI_FPGA_CFG_INT_EN_EXT_BIT;
+	ret = pci_write_config_word(pcidev, CTI_FPGA_CFG_INT_EN_REG, cfg_val);
+	if (ret)
+		return pcibios_err_to_errno(ret);
+
+	// RS485 gate needs to be enabled; otherwise RTS/CTS will not work
+	exar_write_reg(priv, CTI_FPGA_RS485_IO_REG, 0x01);
+
+	return 0;
+}
+
+static int cti_port_setup_fpga(struct exar8250 *priv,
+				struct pci_dev *pcidev,
+				struct uart_8250_port *port,
+				int idx)
+{
+	enum cti_port_type port_type;
+	unsigned int offset;
+	int ret;
+
 	if (idx == 0) {
-		switch (pcidev->device) {
-		case PCI_DEVICE_ID_COMMTECH_4222PCI335:
-		case PCI_DEVICE_ID_COMMTECH_4224PCI335:
-			writeb(0x78, p + UART_EXAR_MPIOLVL_7_0);
-			writeb(0x00, p + UART_EXAR_MPIOINV_7_0);
-			writeb(0x00, p + UART_EXAR_MPIOSEL_7_0);
+		ret = cti_board_init_fpga(priv, pcidev);
+		if (ret)
+			return ret;
+	}
+
+	port_type = cti_get_port_type_fpga(priv, pcidev, idx);
+
+	// FPGA shares port offsets with XR17C15X
+	offset = idx * UART_EXAR_XR17C15X_PORT_OFFSET;
+	port->port.type = PORT_XR17D15X;
+
+	port->port.get_divisor = xr17v35x_get_divisor;
+	port->port.set_divisor = xr17v35x_set_divisor;
+	port->port.startup = xr17v35x_startup;
+
+	if (CTI_PORT_TYPE_RS485(port_type)) {
+		port->port.rs485_config = generic_rs485_config;
+		port->port.rs485_supported = generic_rs485_supported;
+	}
+
+	return cti_port_setup_common(priv, pcidev, idx, offset, port);
+}
+
+static void cti_board_init_xr17v35x(struct exar8250 *priv, struct pci_dev *pcidev)
+{
+	// XR17V35X uses the PCIe clock rather than an oscillator
+	priv->osc_freq = CTI_DEFAULT_PCIE_OSC_FREQ;
+}
+
+static int cti_port_setup_xr17v35x(struct exar8250 *priv,
+				struct pci_dev *pcidev,
+				struct uart_8250_port *port,
+				int idx)
+{
+	enum cti_port_type port_type;
+	unsigned int offset;
+	int ret;
+
+	if (idx == 0)
+		cti_board_init_xr17v35x(priv, pcidev);
+
+	port_type = cti_get_port_type_xr17v35x(priv, pcidev, idx);
+
+	offset = idx * UART_EXAR_XR17V35X_PORT_OFFSET;
+	port->port.type = PORT_XR17V35X;
+
+	port->port.get_divisor = xr17v35x_get_divisor;
+	port->port.set_divisor = xr17v35x_set_divisor;
+	port->port.startup = xr17v35x_startup;
+
+	switch (port_type) {
+	case CTI_PORT_TYPE_RS422_485:
+	case CTI_PORT_TYPE_RS232_422_485_HW:
+		port->port.rs485_config = cti_rs485_config_mpio_tristate;
+		port->port.rs485_supported = generic_rs485_supported;
+		break;
+	case CTI_PORT_TYPE_RS232_422_485_SW:
+	case CTI_PORT_TYPE_RS232_422_485_4B:
+	case CTI_PORT_TYPE_RS232_422_485_2B:
+		port->port.rs485_config = generic_rs485_config;
+		port->port.rs485_supported = generic_rs485_supported;
+		break;
+	default:
+		break;
+	}
+
+	ret = cti_port_setup_common(priv, pcidev, idx, offset, port);
+	if (ret)
+		return ret;
+
+	exar_write_reg(priv, (offset + UART_EXAR_8XMODE), 0x00);
+	exar_write_reg(priv, (offset + UART_EXAR_FCTR), UART_FCTR_EXAR_TRGD);
+	exar_write_reg(priv, (offset + UART_EXAR_TXTRG), 128);
+	exar_write_reg(priv, (offset + UART_EXAR_RXTRG), 128);
+
+	return 0;
+}
+
+static void cti_board_init_xr17v25x(struct exar8250 *priv, struct pci_dev *pcidev)
+{
+	cti_board_init_osc_freq(priv, pcidev, CTI_EE_OFF_XR17V25X_OSC_FREQ);
+
+	/* enable interrupts on cards that need the "PLX fix" */
+	switch (pcidev->subsystem_device) {
+	case PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_8_XPRS:
+	case PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_16_XPRS_A:
+	case PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_16_XPRS_B:
+		cti_plx_int_enable(priv);
+		break;
+	default:
+		break;
+	}
+}
+
+static int cti_port_setup_xr17v25x(struct exar8250 *priv,
+				struct pci_dev *pcidev,
+				struct uart_8250_port *port,
+				int idx)
+{
+	enum cti_port_type port_type;
+	unsigned int offset;
+	int ret;
+
+	if (idx == 0)
+		cti_board_init_xr17v25x(priv, pcidev);
+
+	port_type = cti_get_port_type_xr17c15x_xr17v25x(priv, pcidev, idx);
+
+	offset = idx * UART_EXAR_XR17V25X_PORT_OFFSET;
+	port->port.type = PORT_XR17D15X;
+
+	// XR17V25X supports fractional baudrates
+	port->port.get_divisor = xr17v35x_get_divisor;
+	port->port.set_divisor = xr17v35x_set_divisor;
+	port->port.startup = xr17v35x_startup;
+
+	if (CTI_PORT_TYPE_RS485(port_type)) {
+		switch (pcidev->subsystem_device) {
+		// These cards support power on 485 tri-state via MPIO
+		case PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_8_SP:
+		case PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_8_SP_485:
+		case PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_4_4_SP:
+		case PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_6_2_SP:
+		case PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_2_6_SP:
+		case PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_2_XP_OPTO_LEFT:
+		case PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_2_XP_OPTO_RIGHT:
+		case PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_4_XP_OPTO:
+		case PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_4_4_XPRS_OPTO:
+		case PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_8_XPRS_LP:
+		case PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_8_XPRS_LP_485:
+			port->port.rs485_config = cti_rs485_config_mpio_tristate;
 			break;
-		case PCI_DEVICE_ID_COMMTECH_2324PCI335:
-		case PCI_DEVICE_ID_COMMTECH_2328PCI335:
-			writeb(0x00, p + UART_EXAR_MPIOLVL_7_0);
-			writeb(0xc0, p + UART_EXAR_MPIOINV_7_0);
-			writeb(0xc0, p + UART_EXAR_MPIOSEL_7_0);
+		// Otherwise auto or no power on 485 tri-state support
+		default:
+			port->port.rs485_config = generic_rs485_config;
 			break;
 		}
-		writeb(0x00, p + UART_EXAR_MPIOINT_7_0);
-		writeb(0x00, p + UART_EXAR_MPIO3T_7_0);
-		writeb(0x00, p + UART_EXAR_MPIOOD_7_0);
+
+		port->port.rs485_supported = generic_rs485_supported;
 	}
 
+	ret = cti_port_setup_common(priv, pcidev, idx, offset, port);
+	if (ret)
+		return ret;
+
+	exar_write_reg(priv, (offset + UART_EXAR_8XMODE), 0x00);
+	exar_write_reg(priv, (offset + UART_EXAR_FCTR), UART_FCTR_EXAR_TRGD);
+	exar_write_reg(priv, (offset + UART_EXAR_TXTRG), 32);
+	exar_write_reg(priv, (offset + UART_EXAR_RXTRG), 32);
+
 	return 0;
 }
 
-static int
-pci_connect_tech_setup(struct exar8250 *priv, struct pci_dev *pcidev,
-		       struct uart_8250_port *port, int idx)
+static void cti_board_init_xr17c15x(struct exar8250 *priv, struct pci_dev *pcidev)
 {
-	unsigned int offset = idx * 0x200;
-	unsigned int baud = 1843200;
+	cti_board_init_osc_freq(priv, pcidev, CTI_EE_OFF_XR17C15X_OSC_FREQ);
+
+	/* enable interrupts on cards that need the "PLX fix" */
+	switch (pcidev->subsystem_device) {
+	case PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_2_XPRS:
+	case PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_4_XPRS_A:
+	case PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_4_XPRS_B:
+	case PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_2_XPRS_OPTO:
+	case PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_4_XPRS_OPTO_A:
+	case PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_4_XPRS_OPTO_B:
+		cti_plx_int_enable(priv);
+		break;
+	default:
+		break;
+	}
+}
 
-	port->port.uartclk = baud * 16;
-	return default_setup(priv, pcidev, idx, offset, port);
+static int cti_port_setup_xr17c15x(struct exar8250 *priv,
+				struct pci_dev *pcidev,
+				struct uart_8250_port *port,
+				int idx)
+{
+	enum cti_port_type port_type;
+	unsigned int offset;
+
+	if (idx == 0)
+		cti_board_init_xr17c15x(priv, pcidev);
+
+	port_type = cti_get_port_type_xr17c15x_xr17v25x(priv, pcidev, idx);
+
+	offset = idx * UART_EXAR_XR17C15X_PORT_OFFSET;
+	port->port.type = PORT_XR17D15X;
+
+	if (CTI_PORT_TYPE_RS485(port_type)) {
+		switch (pcidev->subsystem_device) {
+		// These cards support power on 485 tri-state via MPIO
+		case PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_8_SP:
+		case PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_8_SP_485:
+		case PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_4_4_SP:
+		case PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_6_2_SP:
+		case PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_2_6_SP:
+		case PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_2_XP_OPTO_LEFT:
+		case PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_2_XP_OPTO_RIGHT:
+		case PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_4_XP_OPTO:
+		case PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_4_4_XPRS_OPTO:
+		case PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_8_XPRS_LP:
+		case PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_8_XPRS_LP_485:
+			port->port.rs485_config = cti_rs485_config_mpio_tristate;
+			break;
+		// Otherwise auto or no power on 485 tri-state support
+		default:
+			port->port.rs485_config = generic_rs485_config;
+			break;
+		}
+
+		port->port.rs485_supported = generic_rs485_supported;
+	}
+
+	return cti_port_setup_common(priv, pcidev, idx, offset, port);
 }
 
 static int
@@ -386,11 +1168,10 @@ static void setup_gpio(struct pci_dev *pcidev, u8 __iomem *p)
 	 * devices will export them as GPIOs, so we pre-configure them safely
 	 * as inputs.
 	 */
-
 	u8 dir = 0x00;
 
 	if  ((pcidev->vendor == PCI_VENDOR_ID_EXAR) &&
-		(pcidev->subsystem_vendor != PCI_VENDOR_ID_SEALEVEL)) {
+	     (pcidev->subsystem_vendor != PCI_VENDOR_ID_SEALEVEL)) {
 		// Configure GPIO as inputs for Commtech adapters
 		dir = 0xff;
 	} else {
@@ -467,27 +1248,6 @@ static void xr17v35x_unregister_gpio(struct uart_8250_port *port)
 	port->port.private_data = NULL;
 }
 
-static int generic_rs485_config(struct uart_port *port, struct ktermios *termios,
-				struct serial_rs485 *rs485)
-{
-	bool is_rs485 = !!(rs485->flags & SER_RS485_ENABLED);
-	u8 __iomem *p = port->membase;
-	u8 value;
-
-	value = readb(p + UART_EXAR_FCTR);
-	if (is_rs485)
-		value |= UART_FCTR_EXAR_485;
-	else
-		value &= ~UART_FCTR_EXAR_485;
-
-	writeb(value, p + UART_EXAR_FCTR);
-
-	if (is_rs485)
-		writeb(UART_EXAR_RS485_DLY(4), p + UART_MSR);
-
-	return 0;
-}
-
 static int sealevel_rs485_config(struct uart_port *port, struct ktermios *termios,
 				  struct serial_rs485 *rs485)
 {
@@ -501,35 +1261,32 @@ static int sealevel_rs485_config(struct uart_port *port, struct ktermios *termio
 	if (ret)
 		return ret;
 
-	if (rs485->flags & SER_RS485_ENABLED) {
-		old_lcr = readb(p + UART_LCR);
+	if (!(rs485->flags & SER_RS485_ENABLED))
+		return 0;
 
-		/* Set EFR[4]=1 to enable enhanced feature registers */
-		efr = readb(p + UART_XR_EFR);
-		efr |= UART_EFR_ECB;
-		writeb(efr, p + UART_XR_EFR);
+	old_lcr = readb(p + UART_LCR);
 
-		/* Set MCR to use DTR as Auto-RS485 Enable signal */
-		writeb(UART_MCR_OUT1, p + UART_MCR);
+	/* Set EFR[4]=1 to enable enhanced feature registers */
+	efr = readb(p + UART_XR_EFR);
+	efr |= UART_EFR_ECB;
+	writeb(efr, p + UART_XR_EFR);
 
-		/* Set LCR[7]=1 to enable access to DLD register */
-		writeb(old_lcr | UART_LCR_DLAB, p + UART_LCR);
+	/* Set MCR to use DTR as Auto-RS485 Enable signal */
+	writeb(UART_MCR_OUT1, p + UART_MCR);
 
-		/* Set DLD[7]=1 for inverted RS485 Enable logic */
-		dld = readb(p + UART_EXAR_DLD);
-		dld |= UART_EXAR_DLD_485_POLARITY;
-		writeb(dld, p + UART_EXAR_DLD);
+	/* Set LCR[7]=1 to enable access to DLD register */
+	writeb(old_lcr | UART_LCR_DLAB, p + UART_LCR);
 
-		writeb(old_lcr, p + UART_LCR);
-	}
+	/* Set DLD[7]=1 for inverted RS485 Enable logic */
+	dld = readb(p + UART_EXAR_DLD);
+	dld |= UART_EXAR_DLD_485_POLARITY;
+	writeb(dld, p + UART_EXAR_DLD);
+
+	writeb(old_lcr, p + UART_LCR);
 
 	return 0;
 }
 
-static const struct serial_rs485 generic_rs485_supported = {
-	.flags = SER_RS485_ENABLED | SER_RS485_RTS_ON_SEND,
-};
-
 static const struct exar8250_platform exar8250_default_platform = {
 	.register_gpio = xr17v35x_register_gpio,
 	.unregister_gpio = xr17v35x_unregister_gpio,
@@ -714,6 +1471,35 @@ static irqreturn_t exar_misc_handler(int irq, void *data)
 	return IRQ_HANDLED;
 }
 
+static unsigned int exar_get_nr_ports(struct exar8250_board *board, struct pci_dev *pcidev)
+{
+	if (pcidev->vendor == PCI_VENDOR_ID_ACCESSIO)
+		return BIT(((pcidev->device & 0x38) >> 3) - 1);
+
+	// Check if board struct overrides number of ports
+	if (board->num_ports > 0)
+		return board->num_ports;
+
+	// Exar encodes # ports in last nibble of PCI Device ID ex. 0358
+	if (pcidev->vendor == PCI_VENDOR_ID_EXAR)
+		return pcidev->device & 0x0f;
+
+	// Handle CTI FPGA cards
+	if (pcidev->vendor == PCI_VENDOR_ID_CONNECT_TECH) {
+		switch (pcidev->device) {
+		case PCI_DEVICE_ID_CONNECT_TECH_PCI_XR79X_12_XIG00X:
+		case PCI_DEVICE_ID_CONNECT_TECH_PCI_XR79X_12_XIG01X:
+			return 12;
+		case PCI_DEVICE_ID_CONNECT_TECH_PCI_XR79X_16:
+			return 16;
+		default:
+			return 0;
+		}
+	}
+
+	return 0;
+}
+
 static int
 exar_pci_probe(struct pci_dev *pcidev, const struct pci_device_id *ent)
 {
@@ -733,12 +1519,9 @@ exar_pci_probe(struct pci_dev *pcidev, const struct pci_device_id *ent)
 
 	maxnr = pci_resource_len(pcidev, bar) >> (board->reg_shift + 3);
 
-	if (pcidev->vendor == PCI_VENDOR_ID_ACCESSIO)
-		nr_ports = BIT(((pcidev->device & 0x38) >> 3) - 1);
-	else if (board->num_ports)
-		nr_ports = board->num_ports;
-	else
-		nr_ports = pcidev->device & 0x0f;
+	nr_ports = exar_get_nr_ports(board, pcidev);
+	if (nr_ports == 0)
+		return dev_err_probe(&pcidev->dev, -ENODEV, "failed to get number of ports\n");
 
 	priv = devm_kzalloc(&pcidev->dev, struct_size(priv, line, nr_ports), GFP_KERNEL);
 	if (!priv)
@@ -771,7 +1554,7 @@ exar_pci_probe(struct pci_dev *pcidev, const struct pci_device_id *ent)
 	for (i = 0; i < nr_ports && i < maxnr; i++) {
 		rc = board->setup(priv, pcidev, &uart, i);
 		if (rc) {
-			dev_err(&pcidev->dev, "Failed to setup port %u\n", i);
+			dev_err_probe(&pcidev->dev, rc, "Failed to setup port %u\n", i);
 			break;
 		}
 
@@ -780,10 +1563,9 @@ exar_pci_probe(struct pci_dev *pcidev, const struct pci_device_id *ent)
 
 		priv->line[i] = serial8250_register_8250_port(&uart);
 		if (priv->line[i] < 0) {
-			dev_err(&pcidev->dev,
-				"Couldn't register serial port %lx, irq %d, type %d, error %d\n",
-				uart.port.iobase, uart.port.irq,
-				uart.port.iotype, priv->line[i]);
+			dev_err_probe(&pcidev->dev, priv->line[i],
+				"Couldn't register serial port %lx, type %d, irq %d\n",
+				uart.port.iobase, uart.port.iotype, uart.port.irq);
 			break;
 		}
 	}
@@ -848,8 +1630,20 @@ static const struct exar8250_board pbn_fastcom335_8 = {
 	.setup		= pci_fastcom335_setup,
 };
 
-static const struct exar8250_board pbn_connect = {
-	.setup		= pci_connect_tech_setup,
+static const struct exar8250_board pbn_cti_xr17c15x = {
+	.setup		= cti_port_setup_xr17c15x,
+};
+
+static const struct exar8250_board pbn_cti_xr17v25x = {
+	.setup		= cti_port_setup_xr17v25x,
+};
+
+static const struct exar8250_board pbn_cti_xr17v35x = {
+	.setup		= cti_port_setup_xr17v35x,
+};
+
+static const struct exar8250_board pbn_cti_fpga = {
+	.setup		= cti_port_setup_fpga,
 };
 
 static const struct exar8250_board pbn_exar_ibm_saturn = {
@@ -896,13 +1690,13 @@ static const struct exar8250_board pbn_exar_XR17V8358 = {
 	.exit		= pci_xr17v35x_exit,
 };
 
-#define CONNECT_DEVICE(devid, sdevid, bd) {				\
-	PCI_DEVICE_SUB(							\
-		PCI_VENDOR_ID_EXAR,					\
-		PCI_DEVICE_ID_EXAR_##devid,				\
-		PCI_SUBVENDOR_ID_CONNECT_TECH,				\
-		PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_##sdevid), 0, 0,	\
-		(kernel_ulong_t)&bd					\
+#define CTI_EXAR_DEVICE(devid, bd) {                    \
+	PCI_DEVICE_SUB(                                 \
+		PCI_VENDOR_ID_EXAR,                     \
+		PCI_DEVICE_ID_EXAR_##devid,             \
+		PCI_SUBVENDOR_ID_CONNECT_TECH,          \
+		PCI_ANY_ID), 0, 0,                      \
+		(kernel_ulong_t)&bd                     \
 	}
 
 #define EXAR_DEVICE(vend, devid, bd) { PCI_DEVICE_DATA(vend, devid, &bd) }
@@ -911,7 +1705,7 @@ static const struct exar8250_board pbn_exar_XR17V8358 = {
 	PCI_DEVICE_SUB(					\
 		PCI_VENDOR_ID_EXAR,			\
 		PCI_DEVICE_ID_EXAR_##devid,		\
-		PCI_VENDOR_ID_IBM,			\
+		PCI_SUBVENDOR_ID_IBM,			\
 		PCI_SUBDEVICE_ID_IBM_##sdevid), 0, 0,	\
 		(kernel_ulong_t)&bd			\
 	}
@@ -934,18 +1728,23 @@ static const struct pci_device_id exar_pci_tbl[] = {
 	EXAR_DEVICE(ACCESSIO, COM_4SM, pbn_exar_XR17C15x),
 	EXAR_DEVICE(ACCESSIO, COM_8SM, pbn_exar_XR17C15x),
 
-	CONNECT_DEVICE(XR17C152, UART_2_232, pbn_connect),
-	CONNECT_DEVICE(XR17C154, UART_4_232, pbn_connect),
-	CONNECT_DEVICE(XR17C158, UART_8_232, pbn_connect),
-	CONNECT_DEVICE(XR17C152, UART_1_1, pbn_connect),
-	CONNECT_DEVICE(XR17C154, UART_2_2, pbn_connect),
-	CONNECT_DEVICE(XR17C158, UART_4_4, pbn_connect),
-	CONNECT_DEVICE(XR17C152, UART_2, pbn_connect),
-	CONNECT_DEVICE(XR17C154, UART_4, pbn_connect),
-	CONNECT_DEVICE(XR17C158, UART_8, pbn_connect),
-	CONNECT_DEVICE(XR17C152, UART_2_485, pbn_connect),
-	CONNECT_DEVICE(XR17C154, UART_4_485, pbn_connect),
-	CONNECT_DEVICE(XR17C158, UART_8_485, pbn_connect),
+	/* Connect Tech cards with Exar vendor/device PCI IDs */
+	CTI_EXAR_DEVICE(XR17C152,       pbn_cti_xr17c15x),
+	CTI_EXAR_DEVICE(XR17C154,       pbn_cti_xr17c15x),
+	CTI_EXAR_DEVICE(XR17C158,       pbn_cti_xr17c15x),
+
+	CTI_EXAR_DEVICE(XR17V252,       pbn_cti_xr17v25x),
+	CTI_EXAR_DEVICE(XR17V254,       pbn_cti_xr17v25x),
+	CTI_EXAR_DEVICE(XR17V258,       pbn_cti_xr17v25x),
+
+	CTI_EXAR_DEVICE(XR17V352,       pbn_cti_xr17v35x),
+	CTI_EXAR_DEVICE(XR17V354,       pbn_cti_xr17v35x),
+	CTI_EXAR_DEVICE(XR17V358,       pbn_cti_xr17v35x),
+
+	/* Connect Tech cards with Connect Tech vendor/device PCI IDs (FPGA based) */
+	EXAR_DEVICE(CONNECT_TECH, PCI_XR79X_12_XIG00X, pbn_cti_fpga),
+	EXAR_DEVICE(CONNECT_TECH, PCI_XR79X_12_XIG01X, pbn_cti_fpga),
+	EXAR_DEVICE(CONNECT_TECH, PCI_XR79X_16,        pbn_cti_fpga),
 
 	IBM_DEVICE(XR17C152, SATURN_SERIAL_ONE_PORT, pbn_exar_ibm_saturn),
 
diff --git a/drivers/tty/serial/8250/8250_mtk.c b/drivers/tty/serial/8250/8250_mtk.c
index d14988d149..b9cca210e1 100644
--- a/drivers/tty/serial/8250/8250_mtk.c
+++ b/drivers/tty/serial/8250/8250_mtk.c
@@ -199,7 +199,7 @@ static int mtk8250_startup(struct uart_port *port)
 
 	if (up->dma) {
 		data->rx_status = DMA_RX_START;
-		uart_circ_clear(&port->state->xmit);
+		kfifo_reset(&port->state->port.xmit_fifo);
 	}
 #endif
 	memset(&port->icount, 0, sizeof(port->icount));
diff --git a/drivers/tty/serial/8250/8250_of.c b/drivers/tty/serial/8250/8250_of.c
index 5d1dd992d8..e14f47ef11 100644
--- a/drivers/tty/serial/8250/8250_of.c
+++ b/drivers/tty/serial/8250/8250_of.c
@@ -18,6 +18,7 @@
 #include <linux/pm_runtime.h>
 #include <linux/clk.h>
 #include <linux/reset.h>
+#include <linux/notifier.h>
 
 #include "8250.h"
 
@@ -26,6 +27,7 @@ struct of_serial_info {
 	struct reset_control *rst;
 	int type;
 	int line;
+	struct notifier_block clk_notifier;
 };
 
 /* Nuvoton NPCM timeout register */
@@ -58,6 +60,26 @@ static int npcm_setup(struct uart_port *port)
 	return 0;
 }
 
+static inline struct of_serial_info *clk_nb_to_info(struct notifier_block *nb)
+{
+	return container_of(nb, struct of_serial_info, clk_notifier);
+}
+
+static int of_platform_serial_clk_notifier_cb(struct notifier_block *nb, unsigned long event,
+					      void *data)
+{
+	struct of_serial_info *info = clk_nb_to_info(nb);
+	struct uart_8250_port *port8250 = serial8250_get_port(info->line);
+	struct clk_notifier_data *ndata = data;
+
+	if (event == POST_RATE_CHANGE) {
+		serial8250_update_uartclk(&port8250->port, ndata->new_rate);
+		return NOTIFY_OK;
+	}
+
+	return NOTIFY_DONE;
+}
+
 /*
  * Fill a struct uart_port for a given device node
  */
@@ -218,7 +240,19 @@ static int of_platform_serial_probe(struct platform_device *ofdev)
 	info->type = port_type;
 	info->line = ret;
 	platform_set_drvdata(ofdev, info);
+
+	if (info->clk) {
+		info->clk_notifier.notifier_call = of_platform_serial_clk_notifier_cb;
+		ret = clk_notifier_register(info->clk, &info->clk_notifier);
+		if (ret) {
+			dev_err_probe(port8250.port.dev, ret, "Failed to set the clock notifier\n");
+			goto err_unregister;
+		}
+	}
+
 	return 0;
+err_unregister:
+	serial8250_unregister_port(info->line);
 err_dispose:
 	pm_runtime_put_sync(&ofdev->dev);
 	pm_runtime_disable(&ofdev->dev);
@@ -234,6 +268,9 @@ static void of_platform_serial_remove(struct platform_device *ofdev)
 {
 	struct of_serial_info *info = platform_get_drvdata(ofdev);
 
+	if (info->clk)
+		clk_notifier_unregister(info->clk, &info->clk_notifier);
+
 	serial8250_unregister_port(info->line);
 
 	reset_control_assert(info->rst);
diff --git a/drivers/tty/serial/8250/8250_omap.c b/drivers/tty/serial/8250/8250_omap.c
index ddf23ccbc9..1af9aed99c 100644
--- a/drivers/tty/serial/8250/8250_omap.c
+++ b/drivers/tty/serial/8250/8250_omap.c
@@ -19,7 +19,6 @@
 #include <linux/platform_device.h>
 #include <linux/slab.h>
 #include <linux/of.h>
-#include <linux/of_gpio.h>
 #include <linux/of_irq.h>
 #include <linux/delay.h>
 #include <linux/pm_runtime.h>
@@ -1110,7 +1109,7 @@ static void omap_8250_dma_tx_complete(void *param)
 {
 	struct uart_8250_port	*p = param;
 	struct uart_8250_dma	*dma = p->dma;
-	struct circ_buf		*xmit = &p->port.state->xmit;
+	struct tty_port		*tport = &p->port.state->port;
 	unsigned long		flags;
 	bool			en_thri = false;
 	struct omap8250_priv	*priv = p->port.private_data;
@@ -1129,10 +1128,10 @@ static void omap_8250_dma_tx_complete(void *param)
 		omap8250_restore_regs(p);
 	}
 
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+	if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)
 		uart_write_wakeup(&p->port);
 
-	if (!uart_circ_empty(xmit) && !uart_tx_stopped(&p->port)) {
+	if (!kfifo_is_empty(&tport->xmit_fifo) && !uart_tx_stopped(&p->port)) {
 		int ret;
 
 		ret = omap_8250_tx_dma(p);
@@ -1154,14 +1153,15 @@ static int omap_8250_tx_dma(struct uart_8250_port *p)
 {
 	struct uart_8250_dma		*dma = p->dma;
 	struct omap8250_priv		*priv = p->port.private_data;
-	struct circ_buf			*xmit = &p->port.state->xmit;
+	struct tty_port			*tport = &p->port.state->port;
 	struct dma_async_tx_descriptor	*desc;
-	unsigned int	skip_byte = 0;
+	struct scatterlist sg;
+	int skip_byte = -1;
 	int ret;
 
 	if (dma->tx_running)
 		return 0;
-	if (uart_tx_stopped(&p->port) || uart_circ_empty(xmit)) {
+	if (uart_tx_stopped(&p->port) || kfifo_is_empty(&tport->xmit_fifo)) {
 
 		/*
 		 * Even if no data, we need to return an error for the two cases
@@ -1176,8 +1176,18 @@ static int omap_8250_tx_dma(struct uart_8250_port *p)
 		return 0;
 	}
 
-	dma->tx_size = CIRC_CNT_TO_END(xmit->head, xmit->tail, UART_XMIT_SIZE);
+	sg_init_table(&sg, 1);
+	ret = kfifo_dma_out_prepare_mapped(&tport->xmit_fifo, &sg, 1,
+					   UART_XMIT_SIZE, dma->tx_addr);
+	if (ret != 1) {
+		serial8250_clear_THRI(p);
+		return 0;
+	}
+
+	dma->tx_size = sg_dma_len(&sg);
+
 	if (priv->habit & OMAP_DMA_TX_KICK) {
+		unsigned char c;
 		u8 tx_lvl;
 
 		/*
@@ -1204,12 +1214,17 @@ static int omap_8250_tx_dma(struct uart_8250_port *p)
 			ret = -EINVAL;
 			goto err;
 		}
-		skip_byte = 1;
+		if (!kfifo_get(&tport->xmit_fifo, &c)) {
+			ret = -EINVAL;
+			goto err;
+		}
+		skip_byte = c;
+		/* now we need to recompute due to kfifo_get */
+		kfifo_dma_out_prepare_mapped(&tport->xmit_fifo, &sg, 1,
+				UART_XMIT_SIZE, dma->tx_addr);
 	}
 
-	desc = dmaengine_prep_slave_single(dma->txchan,
-			dma->tx_addr + xmit->tail + skip_byte,
-			dma->tx_size - skip_byte, DMA_MEM_TO_DEV,
+	desc = dmaengine_prep_slave_sg(dma->txchan, &sg, 1, DMA_MEM_TO_DEV,
 			DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
 	if (!desc) {
 		ret = -EBUSY;
@@ -1231,11 +1246,13 @@ static int omap_8250_tx_dma(struct uart_8250_port *p)
 		dma->tx_err = 0;
 
 	serial8250_clear_THRI(p);
-	if (skip_byte)
-		serial_out(p, UART_TX, xmit->buf[xmit->tail]);
-	return 0;
+	ret = 0;
+	goto out_skip;
 err:
 	dma->tx_err = 1;
+out_skip:
+	if (skip_byte >= 0)
+		serial_out(p, UART_TX, skip_byte);
 	return ret;
 }
 
@@ -1324,7 +1341,7 @@ static int omap_8250_dma_handle_irq(struct uart_port *port)
 	serial8250_modem_status(up);
 	if (status & UART_LSR_THRE && up->dma->tx_err) {
 		if (uart_tx_stopped(&up->port) ||
-		    uart_circ_empty(&up->port.state->xmit)) {
+		    kfifo_is_empty(&up->port.state->port.xmit_fifo)) {
 			up->dma->tx_err = 0;
 			serial8250_tx_chars(up);
 		} else  {
diff --git a/drivers/tty/serial/8250/8250_pci.c b/drivers/tty/serial/8250/8250_pci.c
index fe0fb2b4e9..e1d7aa2fa3 100644
--- a/drivers/tty/serial/8250/8250_pci.c
+++ b/drivers/tty/serial/8250/8250_pci.c
@@ -4119,7 +4119,7 @@ pciserial_init_ports(struct pci_dev *dev, const struct pciserial_board *board)
 			rc = pci_alloc_irq_vectors(dev, 1, 1, PCI_IRQ_ALL_TYPES);
 		} else {
 			pci_dbg(dev, "Using legacy interrupts\n");
-			rc = pci_alloc_irq_vectors(dev, 1, 1, PCI_IRQ_LEGACY);
+			rc = pci_alloc_irq_vectors(dev, 1, 1, PCI_IRQ_INTX);
 		}
 		if (rc < 0) {
 			kfree(priv);
diff --git a/drivers/tty/serial/8250/8250_pci1xxxx.c b/drivers/tty/serial/8250/8250_pci1xxxx.c
index 2fbb5851f7..d3930bf32f 100644
--- a/drivers/tty/serial/8250/8250_pci1xxxx.c
+++ b/drivers/tty/serial/8250/8250_pci1xxxx.c
@@ -382,10 +382,10 @@ static void pci1xxxx_rx_burst(struct uart_port *port, u32 uart_status)
 }
 
 static void pci1xxxx_process_write_data(struct uart_port *port,
-					struct circ_buf *xmit,
 					int *data_empty_count,
 					u32 *valid_byte_count)
 {
+	struct tty_port *tport = &port->state->port;
 	u32 valid_burst_count = *valid_byte_count / UART_BURST_SIZE;
 
 	/*
@@ -395,41 +395,36 @@ static void pci1xxxx_process_write_data(struct uart_port *port,
 	 * one byte at a time.
 	 */
 	while (valid_burst_count) {
+		u32 c;
+
 		if (*data_empty_count - UART_BURST_SIZE < 0)
 			break;
-		if (xmit->tail > (UART_XMIT_SIZE - UART_BURST_SIZE))
+		if (kfifo_len(&tport->xmit_fifo) < UART_BURST_SIZE)
+			break;
+		if (WARN_ON(kfifo_out(&tport->xmit_fifo, (u8 *)&c, sizeof(c)) !=
+		    sizeof(c)))
 			break;
-		writel(*(unsigned int *)&xmit->buf[xmit->tail],
-		       port->membase + UART_TX_BURST_FIFO);
+		writel(c, port->membase + UART_TX_BURST_FIFO);
 		*valid_byte_count -= UART_BURST_SIZE;
 		*data_empty_count -= UART_BURST_SIZE;
 		valid_burst_count -= UART_BYTE_SIZE;
-
-		xmit->tail = (xmit->tail + UART_BURST_SIZE) &
-			     (UART_XMIT_SIZE - 1);
 	}
 
 	while (*valid_byte_count) {
-		if (*data_empty_count - UART_BYTE_SIZE < 0)
+		u8 c;
+
+		if (!kfifo_get(&tport->xmit_fifo, &c))
 			break;
-		writeb(xmit->buf[xmit->tail], port->membase +
-		       UART_TX_BYTE_FIFO);
+		writeb(c, port->membase + UART_TX_BYTE_FIFO);
 		*data_empty_count -= UART_BYTE_SIZE;
 		*valid_byte_count -= UART_BYTE_SIZE;
 
 		/*
-		 * When the tail of the circular buffer is reached, the next
-		 * byte is transferred to the beginning of the buffer.
-		 */
-		xmit->tail = (xmit->tail + UART_BYTE_SIZE) &
-			     (UART_XMIT_SIZE - 1);
-
-		/*
 		 * If there are any pending burst count, data is handled by
 		 * transmitting DWORDs at a time.
 		 */
-		if (valid_burst_count && (xmit->tail <
-		   (UART_XMIT_SIZE - UART_BURST_SIZE)))
+		if (valid_burst_count &&
+		    kfifo_len(&tport->xmit_fifo) >= UART_BURST_SIZE)
 			break;
 	}
 }
@@ -437,11 +432,9 @@ static void pci1xxxx_process_write_data(struct uart_port *port,
 static void pci1xxxx_tx_burst(struct uart_port *port, u32 uart_status)
 {
 	struct uart_8250_port *up = up_to_u8250p(port);
+	struct tty_port *tport = &port->state->port;
 	u32 valid_byte_count;
 	int data_empty_count;
-	struct circ_buf *xmit;
-
-	xmit = &port->state->xmit;
 
 	if (port->x_char) {
 		writeb(port->x_char, port->membase + UART_TX);
@@ -450,25 +443,25 @@ static void pci1xxxx_tx_burst(struct uart_port *port, u32 uart_status)
 		return;
 	}
 
-	if ((uart_tx_stopped(port)) || (uart_circ_empty(xmit))) {
+	if ((uart_tx_stopped(port)) || kfifo_is_empty(&tport->xmit_fifo)) {
 		port->ops->stop_tx(port);
 	} else {
 		data_empty_count = (pci1xxxx_read_burst_status(port) &
 				    UART_BST_STAT_TX_COUNT_MASK) >> 8;
 		do {
-			valid_byte_count = uart_circ_chars_pending(xmit);
+			valid_byte_count = kfifo_len(&tport->xmit_fifo);
 
-			pci1xxxx_process_write_data(port, xmit,
+			pci1xxxx_process_write_data(port,
 						    &data_empty_count,
 						    &valid_byte_count);
 
 			port->icount.tx++;
-			if (uart_circ_empty(xmit))
+			if (kfifo_is_empty(&tport->xmit_fifo))
 				break;
 		} while (data_empty_count && valid_byte_count);
 	}
 
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+	if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)
 		uart_write_wakeup(port);
 
 	 /*
@@ -476,7 +469,8 @@ static void pci1xxxx_tx_burst(struct uart_port *port, u32 uart_status)
 	  * the HW can go idle. So we get here once again with empty FIFO and
 	  * disable the interrupt and RPM in __stop_tx()
 	  */
-	if (uart_circ_empty(xmit) && !(up->capabilities & UART_CAP_RPM))
+	if (kfifo_is_empty(&tport->xmit_fifo) &&
+	    !(up->capabilities & UART_CAP_RPM))
 		port->ops->stop_tx(port);
 }
 
diff --git a/drivers/tty/serial/8250/8250_pnp.c b/drivers/tty/serial/8250/8250_pnp.c
index 1974bbadc9..7c06ae79d8 100644
--- a/drivers/tty/serial/8250/8250_pnp.c
+++ b/drivers/tty/serial/8250/8250_pnp.c
@@ -10,6 +10,7 @@
  */
 #include <linux/module.h>
 #include <linux/pci.h>
+#include <linux/pm.h>
 #include <linux/pnp.h>
 #include <linux/string.h>
 #include <linux/kernel.h>
@@ -434,7 +435,9 @@ static int
 serial_pnp_probe(struct pnp_dev *dev, const struct pnp_device_id *dev_id)
 {
 	struct uart_8250_port uart, *port;
-	int ret, line, flags = dev_id->driver_data;
+	int ret, flags = dev_id->driver_data;
+	unsigned char iotype;
+	long line;
 
 	if (flags & UNKNOWN_DEV) {
 		ret = serial_pnp_guess_board(dev);
@@ -443,37 +446,46 @@ serial_pnp_probe(struct pnp_dev *dev, const struct pnp_device_id *dev_id)
 	}
 
 	memset(&uart, 0, sizeof(uart));
-	if (pnp_irq_valid(dev, 0))
-		uart.port.irq = pnp_irq(dev, 0);
 	if ((flags & CIR_PORT) && pnp_port_valid(dev, 2)) {
 		uart.port.iobase = pnp_port_start(dev, 2);
-		uart.port.iotype = UPIO_PORT;
+		iotype = UPIO_PORT;
 	} else if (pnp_port_valid(dev, 0)) {
 		uart.port.iobase = pnp_port_start(dev, 0);
-		uart.port.iotype = UPIO_PORT;
+		iotype = UPIO_PORT;
 	} else if (pnp_mem_valid(dev, 0)) {
 		uart.port.mapbase = pnp_mem_start(dev, 0);
-		uart.port.iotype = UPIO_MEM;
+		uart.port.mapsize = pnp_mem_len(dev, 0);
+		iotype = UPIO_MEM;
 		uart.port.flags = UPF_IOREMAP;
 	} else
 		return -ENODEV;
 
-	dev_dbg(&dev->dev,
-		 "Setup PNP port: port %#lx, mem %#llx, irq %u, type %u\n",
-		 uart.port.iobase, (unsigned long long)uart.port.mapbase,
-		 uart.port.irq, uart.port.iotype);
+	uart.port.uartclk = 1843200;
+	uart.port.dev = &dev->dev;
+	uart.port.flags |= UPF_SKIP_TEST | UPF_BOOT_AUTOCONF;
+
+	ret = uart_read_port_properties(&uart.port);
+	/* no interrupt -> fall back to polling */
+	if (ret == -ENXIO)
+		ret = 0;
+	if (ret)
+		return ret;
+
+	/*
+	 * The previous call may not set iotype correctly when reg-io-width
+	 * property is absent and it doesn't support IO port resource.
+	 */
+	uart.port.iotype = iotype;
 
 	if (flags & CIR_PORT) {
 		uart.port.flags |= UPF_FIXED_PORT | UPF_FIXED_TYPE;
 		uart.port.type = PORT_8250_CIR;
 	}
 
-	uart.port.flags |= UPF_SKIP_TEST | UPF_BOOT_AUTOCONF;
-	if (pnp_irq_flags(dev, 0) & IORESOURCE_IRQ_SHAREABLE)
-		uart.port.flags |= UPF_SHARE_IRQ;
-	uart.port.uartclk = 1843200;
-	device_property_read_u32(&dev->dev, "clock-frequency", &uart.port.uartclk);
-	uart.port.dev = &dev->dev;
+	dev_dbg(&dev->dev,
+		 "Setup PNP port: port %#lx, mem %#llx, size %#llx, irq %u, type %u\n",
+		 uart.port.iobase, (unsigned long long)uart.port.mapbase,
+		 (unsigned long long)uart.port.mapsize, uart.port.irq, uart.port.iotype);
 
 	line = serial8250_register_8250_port(&uart);
 	if (line < 0 || (flags & CIR_PORT))
@@ -483,7 +495,7 @@ serial_pnp_probe(struct pnp_dev *dev, const struct pnp_device_id *dev_id)
 	if (uart_console(&port->port))
 		dev->capabilities |= PNP_CONSOLE;
 
-	pnp_set_drvdata(dev, (void *)((long)line + 1));
+	pnp_set_drvdata(dev, (void *)line);
 	return 0;
 }
 
@@ -492,38 +504,33 @@ static void serial_pnp_remove(struct pnp_dev *dev)
 	long line = (long)pnp_get_drvdata(dev);
 
 	dev->capabilities &= ~PNP_CONSOLE;
-	if (line)
-		serial8250_unregister_port(line - 1);
+	serial8250_unregister_port(line);
 }
 
-static int __maybe_unused serial_pnp_suspend(struct device *dev)
+static int serial_pnp_suspend(struct device *dev)
 {
 	long line = (long)dev_get_drvdata(dev);
 
-	if (!line)
-		return -ENODEV;
-	serial8250_suspend_port(line - 1);
+	serial8250_suspend_port(line);
 	return 0;
 }
 
-static int __maybe_unused serial_pnp_resume(struct device *dev)
+static int serial_pnp_resume(struct device *dev)
 {
 	long line = (long)dev_get_drvdata(dev);
 
-	if (!line)
-		return -ENODEV;
-	serial8250_resume_port(line - 1);
+	serial8250_resume_port(line);
 	return 0;
 }
 
-static SIMPLE_DEV_PM_OPS(serial_pnp_pm_ops, serial_pnp_suspend, serial_pnp_resume);
+static DEFINE_SIMPLE_DEV_PM_OPS(serial_pnp_pm_ops, serial_pnp_suspend, serial_pnp_resume);
 
 static struct pnp_driver serial_pnp_driver = {
 	.name		= "serial",
 	.probe		= serial_pnp_probe,
 	.remove		= serial_pnp_remove,
 	.driver         = {
-		.pm     = &serial_pnp_pm_ops,
+		.pm     = pm_sleep_ptr(&serial_pnp_pm_ops),
 	},
 	.id_table	= pnp_dev_table,
 };
diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
index fc9dd5d452..893bc493f6 100644
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -612,13 +612,6 @@ int serial8250_em485_config(struct uart_port *port, struct ktermios *termios,
 {
 	struct uart_8250_port *up = up_to_u8250p(port);
 
-	/* pick sane settings if the user hasn't */
-	if (!!(rs485->flags & SER_RS485_RTS_ON_SEND) ==
-	    !!(rs485->flags & SER_RS485_RTS_AFTER_SEND)) {
-		rs485->flags |= SER_RS485_RTS_ON_SEND;
-		rs485->flags &= ~SER_RS485_RTS_AFTER_SEND;
-	}
-
 	/*
 	 * Both serial8250_em485_init() and serial8250_em485_destroy()
 	 * are idempotent.
@@ -1630,7 +1623,7 @@ static void serial8250_start_tx(struct uart_port *port)
 	/* Port locked to synchronize UART_IER access against the console. */
 	lockdep_assert_held_once(&port->lock);
 
-	if (!port->x_char && uart_circ_empty(&port->state->xmit))
+	if (!port->x_char && kfifo_is_empty(&port->state->port.xmit_fifo))
 		return;
 
 	serial8250_rpm_get_tx(up);
@@ -1778,7 +1771,7 @@ EXPORT_SYMBOL_GPL(serial8250_rx_chars);
 void serial8250_tx_chars(struct uart_8250_port *up)
 {
 	struct uart_port *port = &up->port;
-	struct circ_buf *xmit = &port->state->xmit;
+	struct tty_port *tport = &port->state->port;
 	int count;
 
 	if (port->x_char) {
@@ -1789,14 +1782,19 @@ void serial8250_tx_chars(struct uart_8250_port *up)
 		serial8250_stop_tx(port);
 		return;
 	}
-	if (uart_circ_empty(xmit)) {
+	if (kfifo_is_empty(&tport->xmit_fifo)) {
 		__stop_tx(up);
 		return;
 	}
 
 	count = up->tx_loadsz;
 	do {
-		serial_out(up, UART_TX, xmit->buf[xmit->tail]);
+		unsigned char c;
+
+		if (!uart_fifo_get(port, &c))
+			break;
+
+		serial_out(up, UART_TX, c);
 		if (up->bugs & UART_BUG_TXRACE) {
 			/*
 			 * The Aspeed BMC virtual UARTs have a bug where data
@@ -1809,9 +1807,7 @@ void serial8250_tx_chars(struct uart_8250_port *up)
 			 */
 			serial_in(up, UART_SCR);
 		}
-		uart_xmit_advance(port, 1);
-		if (uart_circ_empty(xmit))
-			break;
+
 		if ((up->capabilities & UART_CAP_HFIFO) &&
 		    !uart_lsr_tx_empty(serial_in(up, UART_LSR)))
 			break;
@@ -1821,7 +1817,7 @@ void serial8250_tx_chars(struct uart_8250_port *up)
 			break;
 	} while (--count > 0);
 
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+	if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)
 		uart_write_wakeup(port);
 
 	/*
@@ -1829,7 +1825,8 @@ void serial8250_tx_chars(struct uart_8250_port *up)
 	 * HW can go idle. So we get here once again with empty FIFO and disable
 	 * the interrupt and RPM in __stop_tx()
 	 */
-	if (uart_circ_empty(xmit) && !(up->capabilities & UART_CAP_RPM))
+	if (kfifo_is_empty(&tport->xmit_fifo) &&
+	    !(up->capabilities & UART_CAP_RPM))
 		__stop_tx(up);
 }
 EXPORT_SYMBOL_GPL(serial8250_tx_chars);
diff --git a/drivers/tty/serial/8250/Makefile b/drivers/tty/serial/8250/Makefile
index ea2e81f58e..69ac002705 100644
--- a/drivers/tty/serial/8250/Makefile
+++ b/drivers/tty/serial/8250/Makefile
@@ -5,8 +5,6 @@
 
 obj-$(CONFIG_SERIAL_8250)		+= 8250.o 8250_base.o
 8250-y					:= 8250_core.o
-8250-$(CONFIG_ALPHA_GENERIC)		+= 8250_alpha.o
-8250-$(CONFIG_ALPHA_JENSEN)		+= 8250_alpha.o
 8250-$(CONFIG_SERIAL_8250_PNP)		+= 8250_pnp.o
 8250_base-y				:= 8250_port.o
 8250_base-$(CONFIG_SERIAL_8250_DMA)	+= 8250_dma.o
diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
index ffcf4882b2..28e4beeabf 100644
--- a/drivers/tty/serial/Kconfig
+++ b/drivers/tty/serial/Kconfig
@@ -307,11 +307,14 @@ config SERIAL_TEGRA_TCU_CONSOLE
 	  If unsure, say Y.
 
 config SERIAL_MAX3100
-	tristate "MAX3100 support"
+	tristate "MAX3100/3110/3111/3222 support"
 	depends on SPI
 	select SERIAL_CORE
 	help
-	  MAX3100 chip support
+	  This selects support for an advanced UART from Maxim.
+	  Supported ICs are MAX3100, MAX3110, MAX3111, MAX3222.
+
+	  Say Y here if you want to support these ICs.
 
 config SERIAL_MAX310X
 	tristate "MAX310X support"
@@ -1020,42 +1023,32 @@ config SERIAL_SCCNXP_CONSOLE
 	help
 	  Support for console on SCCNXP serial ports.
 
-config SERIAL_SC16IS7XX_CORE
-	tristate
-
 config SERIAL_SC16IS7XX
-	tristate "SC16IS7xx serial support"
+	tristate "NXP SC16IS7xx UART support"
+	depends on SPI_MASTER || I2C
 	select SERIAL_CORE
-	depends on (SPI_MASTER && !I2C) || I2C
+	select SERIAL_SC16IS7XX_SPI if SPI_MASTER
+	select SERIAL_SC16IS7XX_I2C if I2C
 	help
-	  This selects support for SC16IS7xx serial ports.
-	  Supported ICs are SC16IS740, SC16IS741, SC16IS750, SC16IS752,
-	  SC16IS760 and SC16IS762. Select supported buses using options below.
+	  Core driver for NXP SC16IS7xx UARTs.
+	  Supported ICs are:
+
+	    SC16IS740
+	    SC16IS741
+	    SC16IS750
+	    SC16IS752
+	    SC16IS760
+	    SC16IS762
+
+	  The driver supports both I2C and SPI interfaces.
 
 config SERIAL_SC16IS7XX_I2C
-	bool "SC16IS7xx for I2C interface"
-	depends on SERIAL_SC16IS7XX
-	depends on I2C
-	select SERIAL_SC16IS7XX_CORE if SERIAL_SC16IS7XX
-	select REGMAP_I2C if I2C
-	default y
-	help
-	  Enable SC16IS7xx driver on I2C bus,
-	  If required say y, and say n to i2c if not required,
-	  Enabled by default to support oldconfig.
-	  You must select at least one bus for the driver to be built.
+	tristate
+	select REGMAP_I2C
 
 config SERIAL_SC16IS7XX_SPI
-	bool "SC16IS7xx for spi interface"
-	depends on SERIAL_SC16IS7XX
-	depends on SPI_MASTER
-	select SERIAL_SC16IS7XX_CORE if SERIAL_SC16IS7XX
-	select REGMAP_SPI if SPI_MASTER
-	help
-	  Enable SC16IS7xx driver on SPI bus,
-	  If required say y, and say n to spi if not required,
-	  This is additional support to existing driver.
-	  You must select at least one bus for the driver to be built.
+	tristate
+	select REGMAP_SPI
 
 config SERIAL_TIMBERDALE
 	tristate "Support for timberdale UART"
diff --git a/drivers/tty/serial/Makefile b/drivers/tty/serial/Makefile
index b25e9b54a6..6ff74f0a95 100644
--- a/drivers/tty/serial/Makefile
+++ b/drivers/tty/serial/Makefile
@@ -75,7 +75,9 @@ obj-$(CONFIG_SERIAL_SA1100)		+= sa1100.o
 obj-$(CONFIG_SERIAL_SAMSUNG)		+= samsung_tty.o
 obj-$(CONFIG_SERIAL_SB1250_DUART)	+= sb1250-duart.o
 obj-$(CONFIG_SERIAL_SCCNXP)		+= sccnxp.o
-obj-$(CONFIG_SERIAL_SC16IS7XX_CORE)	+= sc16is7xx.o
+obj-$(CONFIG_SERIAL_SC16IS7XX)		+= sc16is7xx.o
+obj-$(CONFIG_SERIAL_SC16IS7XX_SPI)	+= sc16is7xx_spi.o
+obj-$(CONFIG_SERIAL_SC16IS7XX_I2C)	+= sc16is7xx_i2c.o
 obj-$(CONFIG_SERIAL_SH_SCI)		+= sh-sci.o
 obj-$(CONFIG_SERIAL_SIFIVE)		+= sifive.o
 obj-$(CONFIG_SERIAL_SPRD)		+= sprd_serial.o
diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
index 2fa3fb30dc..8b1644f541 100644
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -256,7 +256,6 @@ struct uart_amba_port {
 	const u16		*reg_offset;
 	struct clk		*clk;
 	const struct vendor_data *vendor;
-	unsigned int		dmacr;		/* dma control reg */
 	unsigned int		im;		/* interrupt mask */
 	unsigned int		old_status;
 	unsigned int		fifosize;	/* vendor-specific */
@@ -266,6 +265,7 @@ struct uart_amba_port {
 	unsigned int		rs485_tx_drain_interval; /* usecs */
 #ifdef CONFIG_DMA_ENGINE
 	/* DMA stuff */
+	unsigned int		dmacr;		/* dma control reg */
 	bool			using_tx_dma;
 	bool			using_rx_dma;
 	struct pl011_dmarx_data dmarx;
@@ -535,6 +535,7 @@ static void pl011_start_tx_pio(struct uart_amba_port *uap);
 static void pl011_dma_tx_callback(void *data)
 {
 	struct uart_amba_port *uap = data;
+	struct tty_port *tport = &uap->port.state->port;
 	struct pl011_dmatx_data *dmatx = &uap->dmatx;
 	unsigned long flags;
 	u16 dmacr;
@@ -558,7 +559,7 @@ static void pl011_dma_tx_callback(void *data)
 	 * get further refills (hence we check dmacr).
 	 */
 	if (!(dmacr & UART011_TXDMAE) || uart_tx_stopped(&uap->port) ||
-	    uart_circ_empty(&uap->port.state->xmit)) {
+	    kfifo_is_empty(&tport->xmit_fifo)) {
 		uap->dmatx.queued = false;
 		uart_port_unlock_irqrestore(&uap->port, flags);
 		return;
@@ -588,7 +589,7 @@ static int pl011_dma_tx_refill(struct uart_amba_port *uap)
 	struct dma_chan *chan = dmatx->chan;
 	struct dma_device *dma_dev = chan->device;
 	struct dma_async_tx_descriptor *desc;
-	struct circ_buf *xmit = &uap->port.state->xmit;
+	struct tty_port *tport = &uap->port.state->port;
 	unsigned int count;
 
 	/*
@@ -597,7 +598,7 @@ static int pl011_dma_tx_refill(struct uart_amba_port *uap)
 	 * the standard interrupt handling.  This ensures that we
 	 * issue a uart_write_wakeup() at the appropriate time.
 	 */
-	count = uart_circ_chars_pending(xmit);
+	count = kfifo_len(&tport->xmit_fifo);
 	if (count < (uap->fifosize >> 1)) {
 		uap->dmatx.queued = false;
 		return 0;
@@ -613,21 +614,7 @@ static int pl011_dma_tx_refill(struct uart_amba_port *uap)
 	if (count > PL011_DMA_BUFFER_SIZE)
 		count = PL011_DMA_BUFFER_SIZE;
 
-	if (xmit->tail < xmit->head) {
-		memcpy(&dmatx->buf[0], &xmit->buf[xmit->tail], count);
-	} else {
-		size_t first = UART_XMIT_SIZE - xmit->tail;
-		size_t second;
-
-		if (first > count)
-			first = count;
-		second = count - first;
-
-		memcpy(&dmatx->buf[0], &xmit->buf[xmit->tail], first);
-		if (second)
-			memcpy(&dmatx->buf[first], &xmit->buf[0], second);
-	}
-
+	count = kfifo_out_peek(&tport->xmit_fifo, dmatx->buf, count);
 	dmatx->len = count;
 	dmatx->dma = dma_map_single(dma_dev->dev, dmatx->buf, count,
 				    DMA_TO_DEVICE);
@@ -670,7 +657,7 @@ static int pl011_dma_tx_refill(struct uart_amba_port *uap)
 	 */
 	uart_xmit_advance(&uap->port, count);
 
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+	if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)
 		uart_write_wakeup(&uap->port);
 
 	return 1;
@@ -1454,7 +1441,7 @@ static bool pl011_tx_char(struct uart_amba_port *uap, unsigned char c,
 /* Returns true if tx interrupts have to be (kept) enabled  */
 static bool pl011_tx_chars(struct uart_amba_port *uap, bool from_irq)
 {
-	struct circ_buf *xmit = &uap->port.state->xmit;
+	struct tty_port *tport = &uap->port.state->port;
 	int count = uap->fifosize >> 1;
 
 	if (uap->port.x_char) {
@@ -1463,7 +1450,7 @@ static bool pl011_tx_chars(struct uart_amba_port *uap, bool from_irq)
 		uap->port.x_char = 0;
 		--count;
 	}
-	if (uart_circ_empty(xmit) || uart_tx_stopped(&uap->port)) {
+	if (kfifo_is_empty(&tport->xmit_fifo) || uart_tx_stopped(&uap->port)) {
 		pl011_stop_tx(&uap->port);
 		return false;
 	}
@@ -1472,20 +1459,25 @@ static bool pl011_tx_chars(struct uart_amba_port *uap, bool from_irq)
 	if (pl011_dma_tx_irq(uap))
 		return true;
 
-	do {
+	while (1) {
+		unsigned char c;
+
 		if (likely(from_irq) && count-- == 0)
 			break;
 
-		if (!pl011_tx_char(uap, xmit->buf[xmit->tail], from_irq))
+		if (!kfifo_peek(&tport->xmit_fifo, &c))
 			break;
 
-		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
-	} while (!uart_circ_empty(xmit));
+		if (!pl011_tx_char(uap, c, from_irq))
+			break;
+
+		kfifo_skip(&tport->xmit_fifo);
+	}
 
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+	if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)
 		uart_write_wakeup(&uap->port);
 
-	if (uart_circ_empty(xmit)) {
+	if (kfifo_is_empty(&tport->xmit_fifo)) {
 		pl011_stop_tx(&uap->port);
 		return false;
 	}
@@ -2700,18 +2692,6 @@ static int pl011_find_free_port(void)
 	return -EBUSY;
 }
 
-static int pl011_get_rs485_mode(struct uart_amba_port *uap)
-{
-	struct uart_port *port = &uap->port;
-	int ret;
-
-	ret = uart_get_rs485_mode(port);
-	if (ret)
-		return ret;
-
-	return 0;
-}
-
 static int pl011_setup_port(struct device *dev, struct uart_amba_port *uap,
 			    struct resource *mmiobase, int index)
 {
@@ -2732,7 +2712,7 @@ static int pl011_setup_port(struct device *dev, struct uart_amba_port *uap,
 	uap->port.flags = UPF_BOOT_AUTOCONF;
 	uap->port.line = index;
 
-	ret = pl011_get_rs485_mode(uap);
+	ret = uart_get_rs485_mode(&uap->port);
 	if (ret)
 		return ret;
 
diff --git a/drivers/tty/serial/ar933x_uart.c b/drivers/tty/serial/ar933x_uart.c
index 7790cbc573..47889a5571 100644
--- a/drivers/tty/serial/ar933x_uart.c
+++ b/drivers/tty/serial/ar933x_uart.c
@@ -390,7 +390,7 @@ static void ar933x_uart_rx_chars(struct ar933x_uart_port *up)
 
 static void ar933x_uart_tx_chars(struct ar933x_uart_port *up)
 {
-	struct circ_buf *xmit = &up->port.state->xmit;
+	struct tty_port *tport = &up->port.state->port;
 	struct serial_rs485 *rs485conf = &up->port.rs485;
 	int count;
 	bool half_duplex_send = false;
@@ -399,7 +399,7 @@ static void ar933x_uart_tx_chars(struct ar933x_uart_port *up)
 		return;
 
 	if ((rs485conf->flags & SER_RS485_ENABLED) &&
-	    (up->port.x_char || !uart_circ_empty(xmit))) {
+	    (up->port.x_char || !kfifo_is_empty(&tport->xmit_fifo))) {
 		ar933x_uart_stop_rx_interrupt(up);
 		gpiod_set_value(up->rts_gpiod, !!(rs485conf->flags & SER_RS485_RTS_ON_SEND));
 		half_duplex_send = true;
@@ -408,6 +408,7 @@ static void ar933x_uart_tx_chars(struct ar933x_uart_port *up)
 	count = up->port.fifosize;
 	do {
 		unsigned int rdata;
+		unsigned char c;
 
 		rdata = ar933x_uart_read(up, AR933X_UART_DATA_REG);
 		if ((rdata & AR933X_UART_DATA_TX_CSR) == 0)
@@ -420,18 +421,16 @@ static void ar933x_uart_tx_chars(struct ar933x_uart_port *up)
 			continue;
 		}
 
-		if (uart_circ_empty(xmit))
+		if (!uart_fifo_get(&up->port, &c))
 			break;
 
-		ar933x_uart_putc(up, xmit->buf[xmit->tail]);
-
-		uart_xmit_advance(&up->port, 1);
+		ar933x_uart_putc(up, c);
 	} while (--count > 0);
 
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+	if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)
 		uart_write_wakeup(&up->port);
 
-	if (!uart_circ_empty(xmit)) {
+	if (!kfifo_is_empty(&tport->xmit_fifo)) {
 		ar933x_uart_start_tx_interrupt(up);
 	} else if (half_duplex_send) {
 		ar933x_uart_wait_tx_complete(up);
@@ -693,7 +692,6 @@ static struct uart_driver ar933x_uart_driver = {
 	.cons		= NULL, /* filled in runtime */
 };
 
-static const struct serial_rs485 ar933x_no_rs485 = {};
 static const struct serial_rs485 ar933x_rs485_supported = {
 	.flags = SER_RS485_ENABLED | SER_RS485_RTS_ON_SEND | SER_RS485_RTS_AFTER_SEND,
 };
@@ -789,7 +787,7 @@ static int ar933x_uart_probe(struct platform_device *pdev)
 	up->rts_gpiod = mctrl_gpio_to_gpiod(up->gpios, UART_GPIO_RTS);
 
 	if (!up->rts_gpiod) {
-		port->rs485_supported = ar933x_no_rs485;
+		port->rs485_supported.flags &= ~SER_RS485_ENABLED;
 		if (port->rs485.flags & SER_RS485_ENABLED) {
 			dev_err(&pdev->dev, "lacking rts-gpio, disabling RS485\n");
 			port->rs485.flags &= ~SER_RS485_ENABLED;
diff --git a/drivers/tty/serial/arc_uart.c b/drivers/tty/serial/arc_uart.c
index 1aa5b2b49c..5c4895d154 100644
--- a/drivers/tty/serial/arc_uart.c
+++ b/drivers/tty/serial/arc_uart.c
@@ -155,7 +155,7 @@ static unsigned int arc_serial_tx_empty(struct uart_port *port)
  */
 static void arc_serial_tx_chars(struct uart_port *port)
 {
-	struct circ_buf *xmit = &port->state->xmit;
+	struct tty_port *tport = &port->state->port;
 	int sent = 0;
 	unsigned char ch;
 
@@ -164,9 +164,7 @@ static void arc_serial_tx_chars(struct uart_port *port)
 		port->icount.tx++;
 		port->x_char = 0;
 		sent = 1;
-	} else if (!uart_circ_empty(xmit)) {
-		ch = xmit->buf[xmit->tail];
-		uart_xmit_advance(port, 1);
+	} else if (uart_fifo_get(port, &ch)) {
 		while (!(UART_GET_STATUS(port) & TXEMPTY))
 			cpu_relax();
 		UART_SET_DATA(port, ch);
@@ -177,7 +175,7 @@ static void arc_serial_tx_chars(struct uart_port *port)
 	 * If num chars in xmit buffer are too few, ask tty layer for more.
 	 * By Hard ISR to schedule processing in software interrupt part
 	 */
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+	if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)
 		uart_write_wakeup(port);
 
 	if (sent)
diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c
index 85667f7095..0a90964d6d 100644
--- a/drivers/tty/serial/atmel_serial.c
+++ b/drivers/tty/serial/atmel_serial.c
@@ -96,7 +96,9 @@ struct atmel_uart_char {
  * can contain up to 1024 characters in PIO mode and up to 4096 characters in
  * DMA mode.
  */
-#define ATMEL_SERIAL_RINGSIZE 1024
+#define ATMEL_SERIAL_RINGSIZE	1024
+#define ATMEL_SERIAL_RX_SIZE	array_size(sizeof(struct atmel_uart_char), \
+					   ATMEL_SERIAL_RINGSIZE)
 
 /*
  * at91: 6 USARTs and one DBGU port (SAM9260)
@@ -132,8 +134,8 @@ struct atmel_uart_port {
 	struct dma_async_tx_descriptor	*desc_rx;
 	dma_cookie_t			cookie_tx;
 	dma_cookie_t			cookie_rx;
-	struct scatterlist		sg_tx;
-	struct scatterlist		sg_rx;
+	dma_addr_t			tx_phys;
+	dma_addr_t			rx_phys;
 	struct tasklet_struct	tasklet_rx;
 	struct tasklet_struct	tasklet_tx;
 	atomic_t		tasklet_shutdown;
@@ -857,7 +859,7 @@ static void atmel_complete_tx_dma(void *arg)
 {
 	struct atmel_uart_port *atmel_port = arg;
 	struct uart_port *port = &atmel_port->uart;
-	struct circ_buf *xmit = &port->state->xmit;
+	struct tty_port *tport = &port->state->port;
 	struct dma_chan *chan = atmel_port->chan_tx;
 	unsigned long flags;
 
@@ -873,15 +875,15 @@ static void atmel_complete_tx_dma(void *arg)
 	atmel_port->desc_tx = NULL;
 	spin_unlock(&atmel_port->lock_tx);
 
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+	if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)
 		uart_write_wakeup(port);
 
 	/*
-	 * xmit is a circular buffer so, if we have just send data from
-	 * xmit->tail to the end of xmit->buf, now we have to transmit the
-	 * remaining data from the beginning of xmit->buf to xmit->head.
+	 * xmit is a circular buffer so, if we have just send data from the
+	 * tail to the end, now we have to transmit the remaining data from the
+	 * beginning to the head.
 	 */
-	if (!uart_circ_empty(xmit))
+	if (!kfifo_is_empty(&tport->xmit_fifo))
 		atmel_tasklet_schedule(atmel_port, &atmel_port->tasklet_tx);
 	else if (atmel_uart_is_half_duplex(port)) {
 		/*
@@ -904,8 +906,8 @@ static void atmel_release_tx_dma(struct uart_port *port)
 	if (chan) {
 		dmaengine_terminate_all(chan);
 		dma_release_channel(chan);
-		dma_unmap_sg(port->dev, &atmel_port->sg_tx, 1,
-				DMA_TO_DEVICE);
+		dma_unmap_single(port->dev, atmel_port->tx_phys,
+				 UART_XMIT_SIZE, DMA_TO_DEVICE);
 	}
 
 	atmel_port->desc_tx = NULL;
@@ -919,18 +921,18 @@ static void atmel_release_tx_dma(struct uart_port *port)
 static void atmel_tx_dma(struct uart_port *port)
 {
 	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
-	struct circ_buf *xmit = &port->state->xmit;
+	struct tty_port *tport = &port->state->port;
 	struct dma_chan *chan = atmel_port->chan_tx;
 	struct dma_async_tx_descriptor *desc;
-	struct scatterlist sgl[2], *sg, *sg_tx = &atmel_port->sg_tx;
-	unsigned int tx_len, part1_len, part2_len, sg_len;
+	struct scatterlist sgl[2], *sg;
+	unsigned int tx_len, tail, part1_len, part2_len, sg_len;
 	dma_addr_t phys_addr;
 
 	/* Make sure we have an idle channel */
 	if (atmel_port->desc_tx != NULL)
 		return;
 
-	if (!uart_circ_empty(xmit) && !uart_tx_stopped(port)) {
+	if (!kfifo_is_empty(&tport->xmit_fifo) && !uart_tx_stopped(port)) {
 		/*
 		 * DMA is idle now.
 		 * Port xmit buffer is already mapped,
@@ -940,9 +942,8 @@ static void atmel_tx_dma(struct uart_port *port)
 		 * Take the port lock to get a
 		 * consistent xmit buffer state.
 		 */
-		tx_len = CIRC_CNT_TO_END(xmit->head,
-					 xmit->tail,
-					 UART_XMIT_SIZE);
+		tx_len = kfifo_out_linear(&tport->xmit_fifo, &tail,
+				UART_XMIT_SIZE);
 
 		if (atmel_port->fifo_size) {
 			/* multi data mode */
@@ -956,7 +957,7 @@ static void atmel_tx_dma(struct uart_port *port)
 
 		sg_init_table(sgl, 2);
 		sg_len = 0;
-		phys_addr = sg_dma_address(sg_tx) + xmit->tail;
+		phys_addr = atmel_port->tx_phys + tail;
 		if (part1_len) {
 			sg = &sgl[sg_len++];
 			sg_dma_address(sg) = phys_addr;
@@ -973,7 +974,7 @@ static void atmel_tx_dma(struct uart_port *port)
 
 		/*
 		 * save tx_len so atmel_complete_tx_dma() will increase
-		 * xmit->tail correctly
+		 * tail correctly
 		 */
 		atmel_port->tx_len = tx_len;
 
@@ -988,7 +989,8 @@ static void atmel_tx_dma(struct uart_port *port)
 			return;
 		}
 
-		dma_sync_sg_for_device(port->dev, sg_tx, 1, DMA_TO_DEVICE);
+		dma_sync_single_for_device(port->dev, atmel_port->tx_phys,
+					   UART_XMIT_SIZE, DMA_TO_DEVICE);
 
 		atmel_port->desc_tx = desc;
 		desc->callback = atmel_complete_tx_dma;
@@ -1003,18 +1005,19 @@ static void atmel_tx_dma(struct uart_port *port)
 		dma_async_issue_pending(chan);
 	}
 
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+	if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)
 		uart_write_wakeup(port);
 }
 
 static int atmel_prepare_tx_dma(struct uart_port *port)
 {
 	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
+	struct tty_port *tport = &port->state->port;
 	struct device *mfd_dev = port->dev->parent;
 	dma_cap_mask_t		mask;
 	struct dma_slave_config config;
 	struct dma_chan *chan;
-	int ret, nent;
+	int ret;
 
 	dma_cap_zero(mask);
 	dma_cap_set(DMA_SLAVE, mask);
@@ -1029,26 +1032,18 @@ static int atmel_prepare_tx_dma(struct uart_port *port)
 		dma_chan_name(atmel_port->chan_tx));
 
 	spin_lock_init(&atmel_port->lock_tx);
-	sg_init_table(&atmel_port->sg_tx, 1);
 	/* UART circular tx buffer is an aligned page. */
-	BUG_ON(!PAGE_ALIGNED(port->state->xmit.buf));
-	sg_set_page(&atmel_port->sg_tx,
-			virt_to_page(port->state->xmit.buf),
-			UART_XMIT_SIZE,
-			offset_in_page(port->state->xmit.buf));
-	nent = dma_map_sg(port->dev,
-				&atmel_port->sg_tx,
-				1,
-				DMA_TO_DEVICE);
-
-	if (!nent) {
+	BUG_ON(!PAGE_ALIGNED(tport->xmit_buf));
+	atmel_port->tx_phys = dma_map_single(port->dev, tport->xmit_buf,
+					     UART_XMIT_SIZE, DMA_TO_DEVICE);
+
+	if (dma_mapping_error(port->dev, atmel_port->tx_phys)) {
 		dev_dbg(port->dev, "need to release resource of dma\n");
 		goto chan_err;
 	} else {
-		dev_dbg(port->dev, "%s: mapped %d@%p to %pad\n", __func__,
-			sg_dma_len(&atmel_port->sg_tx),
-			port->state->xmit.buf,
-			&sg_dma_address(&atmel_port->sg_tx));
+		dev_dbg(port->dev, "%s: mapped %lu@%p to %pad\n", __func__,
+			UART_XMIT_SIZE, tport->xmit_buf,
+			&atmel_port->tx_phys);
 	}
 
 	/* Configure the slave DMA */
@@ -1093,8 +1088,8 @@ static void atmel_release_rx_dma(struct uart_port *port)
 	if (chan) {
 		dmaengine_terminate_all(chan);
 		dma_release_channel(chan);
-		dma_unmap_sg(port->dev, &atmel_port->sg_rx, 1,
-				DMA_FROM_DEVICE);
+		dma_unmap_single(port->dev, atmel_port->rx_phys,
+				 ATMEL_SERIAL_RX_SIZE, DMA_FROM_DEVICE);
 	}
 
 	atmel_port->desc_rx = NULL;
@@ -1127,10 +1122,8 @@ static void atmel_rx_from_dma(struct uart_port *port)
 	}
 
 	/* CPU claims ownership of RX DMA buffer */
-	dma_sync_sg_for_cpu(port->dev,
-			    &atmel_port->sg_rx,
-			    1,
-			    DMA_FROM_DEVICE);
+	dma_sync_single_for_cpu(port->dev, atmel_port->rx_phys,
+				ATMEL_SERIAL_RX_SIZE, DMA_FROM_DEVICE);
 
 	/*
 	 * ring->head points to the end of data already written by the DMA.
@@ -1139,8 +1132,8 @@ static void atmel_rx_from_dma(struct uart_port *port)
 	 * The current transfer size should not be larger than the dma buffer
 	 * length.
 	 */
-	ring->head = sg_dma_len(&atmel_port->sg_rx) - state.residue;
-	BUG_ON(ring->head > sg_dma_len(&atmel_port->sg_rx));
+	ring->head = ATMEL_SERIAL_RX_SIZE - state.residue;
+	BUG_ON(ring->head > ATMEL_SERIAL_RX_SIZE);
 	/*
 	 * At this point ring->head may point to the first byte right after the
 	 * last byte of the dma buffer:
@@ -1154,7 +1147,7 @@ static void atmel_rx_from_dma(struct uart_port *port)
 	 * tail to the end of the buffer then reset tail.
 	 */
 	if (ring->head < ring->tail) {
-		count = sg_dma_len(&atmel_port->sg_rx) - ring->tail;
+		count = ATMEL_SERIAL_RX_SIZE - ring->tail;
 
 		tty_insert_flip_string(tport, ring->buf + ring->tail, count);
 		ring->tail = 0;
@@ -1167,17 +1160,15 @@ static void atmel_rx_from_dma(struct uart_port *port)
 
 		tty_insert_flip_string(tport, ring->buf + ring->tail, count);
 		/* Wrap ring->head if needed */
-		if (ring->head >= sg_dma_len(&atmel_port->sg_rx))
+		if (ring->head >= ATMEL_SERIAL_RX_SIZE)
 			ring->head = 0;
 		ring->tail = ring->head;
 		port->icount.rx += count;
 	}
 
 	/* USART retreives ownership of RX DMA buffer */
-	dma_sync_sg_for_device(port->dev,
-			       &atmel_port->sg_rx,
-			       1,
-			       DMA_FROM_DEVICE);
+	dma_sync_single_for_device(port->dev, atmel_port->rx_phys,
+				   ATMEL_SERIAL_RX_SIZE, DMA_FROM_DEVICE);
 
 	tty_flip_buffer_push(tport);
 
@@ -1193,7 +1184,7 @@ static int atmel_prepare_rx_dma(struct uart_port *port)
 	struct dma_slave_config config;
 	struct circ_buf		*ring;
 	struct dma_chan *chan;
-	int ret, nent;
+	int ret;
 
 	ring = &atmel_port->rx_ring;
 
@@ -1210,26 +1201,18 @@ static int atmel_prepare_rx_dma(struct uart_port *port)
 		dma_chan_name(atmel_port->chan_rx));
 
 	spin_lock_init(&atmel_port->lock_rx);
-	sg_init_table(&atmel_port->sg_rx, 1);
 	/* UART circular rx buffer is an aligned page. */
 	BUG_ON(!PAGE_ALIGNED(ring->buf));
-	sg_set_page(&atmel_port->sg_rx,
-		    virt_to_page(ring->buf),
-		    sizeof(struct atmel_uart_char) * ATMEL_SERIAL_RINGSIZE,
-		    offset_in_page(ring->buf));
-	nent = dma_map_sg(port->dev,
-			  &atmel_port->sg_rx,
-			  1,
-			  DMA_FROM_DEVICE);
-
-	if (!nent) {
+	atmel_port->rx_phys = dma_map_single(port->dev, ring->buf,
+					     ATMEL_SERIAL_RX_SIZE,
+					     DMA_FROM_DEVICE);
+
+	if (dma_mapping_error(port->dev, atmel_port->rx_phys)) {
 		dev_dbg(port->dev, "need to release resource of dma\n");
 		goto chan_err;
 	} else {
-		dev_dbg(port->dev, "%s: mapped %d@%p to %pad\n", __func__,
-			sg_dma_len(&atmel_port->sg_rx),
-			ring->buf,
-			&sg_dma_address(&atmel_port->sg_rx));
+		dev_dbg(port->dev, "%s: mapped %zu@%p to %pad\n", __func__,
+			ATMEL_SERIAL_RX_SIZE, ring->buf, &atmel_port->rx_phys);
 	}
 
 	/* Configure the slave DMA */
@@ -1250,9 +1233,9 @@ static int atmel_prepare_rx_dma(struct uart_port *port)
 	 * each one is half ring buffer size
 	 */
 	desc = dmaengine_prep_dma_cyclic(atmel_port->chan_rx,
-					 sg_dma_address(&atmel_port->sg_rx),
-					 sg_dma_len(&atmel_port->sg_rx),
-					 sg_dma_len(&atmel_port->sg_rx)/2,
+					 atmel_port->rx_phys,
+					 ATMEL_SERIAL_RX_SIZE,
+					 ATMEL_SERIAL_RX_SIZE / 2,
 					 DMA_DEV_TO_MEM,
 					 DMA_PREP_INTERRUPT);
 	if (!desc) {
@@ -1459,9 +1442,8 @@ static void atmel_release_tx_pdc(struct uart_port *port)
 static void atmel_tx_pdc(struct uart_port *port)
 {
 	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
-	struct circ_buf *xmit = &port->state->xmit;
+	struct tty_port *tport = &port->state->port;
 	struct atmel_dma_buffer *pdc = &atmel_port->pdc_tx;
-	int count;
 
 	/* nothing left to transmit? */
 	if (atmel_uart_readl(port, ATMEL_PDC_TCR))
@@ -1474,17 +1456,19 @@ static void atmel_tx_pdc(struct uart_port *port)
 	/* disable PDC transmit */
 	atmel_uart_writel(port, ATMEL_PDC_PTCR, ATMEL_PDC_TXTDIS);
 
-	if (!uart_circ_empty(xmit) && !uart_tx_stopped(port)) {
+	if (!kfifo_is_empty(&tport->xmit_fifo) && !uart_tx_stopped(port)) {
+		unsigned int count, tail;
+
 		dma_sync_single_for_device(port->dev,
 					   pdc->dma_addr,
 					   pdc->dma_size,
 					   DMA_TO_DEVICE);
 
-		count = CIRC_CNT_TO_END(xmit->head, xmit->tail, UART_XMIT_SIZE);
+		count = kfifo_out_linear(&tport->xmit_fifo, &tail,
+				UART_XMIT_SIZE);
 		pdc->ofs = count;
 
-		atmel_uart_writel(port, ATMEL_PDC_TPR,
-				  pdc->dma_addr + xmit->tail);
+		atmel_uart_writel(port, ATMEL_PDC_TPR, pdc->dma_addr + tail);
 		atmel_uart_writel(port, ATMEL_PDC_TCR, count);
 		/* re-enable PDC transmit */
 		atmel_uart_writel(port, ATMEL_PDC_PTCR, ATMEL_PDC_TXTEN);
@@ -1498,7 +1482,7 @@ static void atmel_tx_pdc(struct uart_port *port)
 		}
 	}
 
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+	if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)
 		uart_write_wakeup(port);
 }
 
@@ -1506,9 +1490,9 @@ static int atmel_prepare_tx_pdc(struct uart_port *port)
 {
 	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
 	struct atmel_dma_buffer *pdc = &atmel_port->pdc_tx;
-	struct circ_buf *xmit = &port->state->xmit;
+	struct tty_port *tport = &port->state->port;
 
-	pdc->buf = xmit->buf;
+	pdc->buf = tport->xmit_buf;
 	pdc->dma_addr = dma_map_single(port->dev,
 					pdc->buf,
 					UART_XMIT_SIZE,
@@ -2953,9 +2937,7 @@ static int atmel_serial_probe(struct platform_device *pdev)
 
 	if (!atmel_use_pdc_rx(&atmel_port->uart)) {
 		ret = -ENOMEM;
-		data = kmalloc_array(ATMEL_SERIAL_RINGSIZE,
-				     sizeof(struct atmel_uart_char),
-				     GFP_KERNEL);
+		data = kmalloc(ATMEL_SERIAL_RX_SIZE, GFP_KERNEL);
 		if (!data)
 			goto err_clk_disable_unprepare;
 		atmel_port->rx_ring.buf = data;
diff --git a/drivers/tty/serial/clps711x.c b/drivers/tty/serial/clps711x.c
index 7927725b89..30425a3d19 100644
--- a/drivers/tty/serial/clps711x.c
+++ b/drivers/tty/serial/clps711x.c
@@ -146,7 +146,8 @@ static irqreturn_t uart_clps711x_int_tx(int irq, void *dev_id)
 {
 	struct uart_port *port = dev_id;
 	struct clps711x_port *s = dev_get_drvdata(port->dev);
-	struct circ_buf *xmit = &port->state->xmit;
+	struct tty_port *tport = &port->state->port;
+	unsigned char c;
 
 	if (port->x_char) {
 		writew(port->x_char, port->membase + UARTDR_OFFSET);
@@ -155,7 +156,7 @@ static irqreturn_t uart_clps711x_int_tx(int irq, void *dev_id)
 		return IRQ_HANDLED;
 	}
 
-	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
+	if (kfifo_is_empty(&tport->xmit_fifo) || uart_tx_stopped(port)) {
 		if (s->tx_enabled) {
 			disable_irq_nosync(port->irq);
 			s->tx_enabled = 0;
@@ -163,18 +164,17 @@ static irqreturn_t uart_clps711x_int_tx(int irq, void *dev_id)
 		return IRQ_HANDLED;
 	}
 
-	while (!uart_circ_empty(xmit)) {
+	while (uart_fifo_get(port, &c)) {
 		u32 sysflg = 0;
 
-		writew(xmit->buf[xmit->tail], port->membase + UARTDR_OFFSET);
-		uart_xmit_advance(port, 1);
+		writew(c, port->membase + UARTDR_OFFSET);
 
 		regmap_read(s->syscon, SYSFLG_OFFSET, &sysflg);
 		if (sysflg & SYSFLG_UTXFF)
 			break;
 	}
 
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+	if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)
 		uart_write_wakeup(port);
 
 	return IRQ_HANDLED;
diff --git a/drivers/tty/serial/cpm_uart.c b/drivers/tty/serial/cpm_uart.c
index df56c6c5af..a927478f58 100644
--- a/drivers/tty/serial/cpm_uart.c
+++ b/drivers/tty/serial/cpm_uart.c
@@ -648,7 +648,7 @@ static int cpm_uart_tx_pump(struct uart_port *port)
 	int count;
 	struct uart_cpm_port *pinfo =
 		container_of(port, struct uart_cpm_port, port);
-	struct circ_buf *xmit = &port->state->xmit;
+	struct tty_port *tport = &port->state->port;
 
 	/* Handle xon/xoff */
 	if (port->x_char) {
@@ -673,7 +673,7 @@ static int cpm_uart_tx_pump(struct uart_port *port)
 		return 1;
 	}
 
-	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
+	if (kfifo_is_empty(&tport->xmit_fifo) || uart_tx_stopped(port)) {
 		cpm_uart_stop_tx(port);
 		return 0;
 	}
@@ -681,16 +681,10 @@ static int cpm_uart_tx_pump(struct uart_port *port)
 	/* Pick next descriptor and fill from buffer */
 	bdp = pinfo->tx_cur;
 
-	while (!(in_be16(&bdp->cbd_sc) & BD_SC_READY) && !uart_circ_empty(xmit)) {
-		count = 0;
+	while (!(in_be16(&bdp->cbd_sc) & BD_SC_READY) &&
+			!kfifo_is_empty(&tport->xmit_fifo)) {
 		p = cpm2cpu_addr(in_be32(&bdp->cbd_bufaddr), pinfo);
-		while (count < pinfo->tx_fifosize) {
-			*p++ = xmit->buf[xmit->tail];
-			uart_xmit_advance(port, 1);
-			count++;
-			if (uart_circ_empty(xmit))
-				break;
-		}
+		count = uart_fifo_out(port, p, pinfo->tx_fifosize);
 		out_be16(&bdp->cbd_datlen, count);
 		setbits16(&bdp->cbd_sc, BD_SC_READY);
 		/* Get next BD. */
@@ -701,10 +695,10 @@ static int cpm_uart_tx_pump(struct uart_port *port)
 	}
 	pinfo->tx_cur = bdp;
 
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+	if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)
 		uart_write_wakeup(port);
 
-	if (uart_circ_empty(xmit)) {
+	if (kfifo_is_empty(&tport->xmit_fifo)) {
 		cpm_uart_stop_tx(port);
 		return 0;
 	}
diff --git a/drivers/tty/serial/digicolor-usart.c b/drivers/tty/serial/digicolor-usart.c
index e419c4bde8..2ccd13cc0a 100644
--- a/drivers/tty/serial/digicolor-usart.c
+++ b/drivers/tty/serial/digicolor-usart.c
@@ -179,8 +179,9 @@ static void digicolor_uart_rx(struct uart_port *port)
 
 static void digicolor_uart_tx(struct uart_port *port)
 {
-	struct circ_buf *xmit = &port->state->xmit;
+	struct tty_port *tport = &port->state->port;
 	unsigned long flags;
+	unsigned char c;
 
 	if (digicolor_uart_tx_full(port))
 		return;
@@ -194,20 +195,19 @@ static void digicolor_uart_tx(struct uart_port *port)
 		goto out;
 	}
 
-	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
+	if (kfifo_is_empty(&tport->xmit_fifo) || uart_tx_stopped(port)) {
 		digicolor_uart_stop_tx(port);
 		goto out;
 	}
 
-	while (!uart_circ_empty(xmit)) {
-		writeb(xmit->buf[xmit->tail], port->membase + UA_EMI_REC);
-		uart_xmit_advance(port, 1);
+	while (uart_fifo_get(port, &c)) {
+		writeb(c, port->membase + UA_EMI_REC);
 
 		if (digicolor_uart_tx_full(port))
 			break;
 	}
 
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+	if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)
 		uart_write_wakeup(port);
 
 out:
diff --git a/drivers/tty/serial/dz.c b/drivers/tty/serial/dz.c
index 6df7af9edc..eba91daede 100644
--- a/drivers/tty/serial/dz.c
+++ b/drivers/tty/serial/dz.c
@@ -252,13 +252,13 @@ static inline void dz_receive_chars(struct dz_mux *mux)
 static inline void dz_transmit_chars(struct dz_mux *mux)
 {
 	struct dz_port *dport = &mux->dport[0];
-	struct circ_buf *xmit;
+	struct tty_port *tport;
 	unsigned char tmp;
 	u16 status;
 
 	status = dz_in(dport, DZ_CSR);
 	dport = &mux->dport[LINE(status)];
-	xmit = &dport->port.state->xmit;
+	tport = &dport->port.state->port;
 
 	if (dport->port.x_char) {		/* XON/XOFF chars */
 		dz_out(dport, DZ_TDR, dport->port.x_char);
@@ -267,7 +267,8 @@ static inline void dz_transmit_chars(struct dz_mux *mux)
 		return;
 	}
 	/* If nothing to do or stopped or hardware stopped. */
-	if (uart_circ_empty(xmit) || uart_tx_stopped(&dport->port)) {
+	if (uart_tx_stopped(&dport->port) ||
+			!uart_fifo_get(&dport->port, &tmp)) {
 		uart_port_lock(&dport->port);
 		dz_stop_tx(&dport->port);
 		uart_port_unlock(&dport->port);
@@ -278,15 +279,13 @@ static inline void dz_transmit_chars(struct dz_mux *mux)
 	 * If something to do... (remember the dz has no output fifo,
 	 * so we go one char at a time) :-<
 	 */
-	tmp = xmit->buf[xmit->tail];
 	dz_out(dport, DZ_TDR, tmp);
-	uart_xmit_advance(&dport->port, 1);
 
-	if (uart_circ_chars_pending(xmit) < DZ_WAKEUP_CHARS)
+	if (kfifo_len(&tport->xmit_fifo) < DZ_WAKEUP_CHARS)
 		uart_write_wakeup(&dport->port);
 
 	/* Are we are done. */
-	if (uart_circ_empty(xmit)) {
+	if (kfifo_is_empty(&tport->xmit_fifo)) {
 		uart_port_lock(&dport->port);
 		dz_stop_tx(&dport->port);
 		uart_port_unlock(&dport->port);
diff --git a/drivers/tty/serial/fsl_linflexuart.c b/drivers/tty/serial/fsl_linflexuart.c
index 5426322b5f..e972df4b18 100644
--- a/drivers/tty/serial/fsl_linflexuart.c
+++ b/drivers/tty/serial/fsl_linflexuart.c
@@ -174,17 +174,18 @@ static void linflex_put_char(struct uart_port *sport, unsigned char c)
 
 static inline void linflex_transmit_buffer(struct uart_port *sport)
 {
-	struct circ_buf *xmit = &sport->state->xmit;
+	struct tty_port *tport = &sport->state->port;
+	unsigned char c;
 
-	while (!uart_circ_empty(xmit)) {
-		linflex_put_char(sport, xmit->buf[xmit->tail]);
-		uart_xmit_advance(sport, 1);
+	while (uart_fifo_get(sport, &c)) {
+		linflex_put_char(sport, c);
+		sport->icount.tx++;
 	}
 
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+	if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)
 		uart_write_wakeup(sport);
 
-	if (uart_circ_empty(xmit))
+	if (kfifo_is_empty(&tport->xmit_fifo))
 		linflex_stop_tx(sport);
 }
 
@@ -200,7 +201,7 @@ static void linflex_start_tx(struct uart_port *port)
 static irqreturn_t linflex_txint(int irq, void *dev_id)
 {
 	struct uart_port *sport = dev_id;
-	struct circ_buf *xmit = &sport->state->xmit;
+	struct tty_port *tport = &sport->state->port;
 	unsigned long flags;
 
 	uart_port_lock_irqsave(sport, &flags);
@@ -210,7 +211,7 @@ static irqreturn_t linflex_txint(int irq, void *dev_id)
 		goto out;
 	}
 
-	if (uart_circ_empty(xmit) || uart_tx_stopped(sport)) {
+	if (kfifo_is_empty(&tport->xmit_fifo) || uart_tx_stopped(sport)) {
 		linflex_stop_tx(sport);
 		goto out;
 	}
diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c
index bbcbc91482..615291ea9b 100644
--- a/drivers/tty/serial/fsl_lpuart.c
+++ b/drivers/tty/serial/fsl_lpuart.c
@@ -7,6 +7,7 @@
 
 #include <linux/bitfield.h>
 #include <linux/bits.h>
+#include <linux/circ_buf.h>
 #include <linux/clk.h>
 #include <linux/console.h>
 #include <linux/delay.h>
@@ -473,7 +474,7 @@ static void lpuart32_stop_rx(struct uart_port *port)
 
 static void lpuart_dma_tx(struct lpuart_port *sport)
 {
-	struct circ_buf *xmit = &sport->port.state->xmit;
+	struct tty_port *tport = &sport->port.state->port;
 	struct scatterlist *sgl = sport->tx_sgl;
 	struct device *dev = sport->port.dev;
 	struct dma_chan *chan = sport->dma_tx_chan;
@@ -482,18 +483,10 @@ static void lpuart_dma_tx(struct lpuart_port *sport)
 	if (sport->dma_tx_in_progress)
 		return;
 
-	sport->dma_tx_bytes = uart_circ_chars_pending(xmit);
-
-	if (xmit->tail < xmit->head || xmit->head == 0) {
-		sport->dma_tx_nents = 1;
-		sg_init_one(sgl, xmit->buf + xmit->tail, sport->dma_tx_bytes);
-	} else {
-		sport->dma_tx_nents = 2;
-		sg_init_table(sgl, 2);
-		sg_set_buf(sgl, xmit->buf + xmit->tail,
-				UART_XMIT_SIZE - xmit->tail);
-		sg_set_buf(sgl + 1, xmit->buf, xmit->head);
-	}
+	sg_init_table(sgl, ARRAY_SIZE(sport->tx_sgl));
+	sport->dma_tx_bytes = kfifo_len(&tport->xmit_fifo);
+	sport->dma_tx_nents = kfifo_dma_out_prepare(&tport->xmit_fifo, sgl,
+			ARRAY_SIZE(sport->tx_sgl), sport->dma_tx_bytes);
 
 	ret = dma_map_sg(chan->device->dev, sgl, sport->dma_tx_nents,
 			 DMA_TO_DEVICE);
@@ -521,14 +514,15 @@ static void lpuart_dma_tx(struct lpuart_port *sport)
 
 static bool lpuart_stopped_or_empty(struct uart_port *port)
 {
-	return uart_circ_empty(&port->state->xmit) || uart_tx_stopped(port);
+	return kfifo_is_empty(&port->state->port.xmit_fifo) ||
+		uart_tx_stopped(port);
 }
 
 static void lpuart_dma_tx_complete(void *arg)
 {
 	struct lpuart_port *sport = arg;
 	struct scatterlist *sgl = &sport->tx_sgl[0];
-	struct circ_buf *xmit = &sport->port.state->xmit;
+	struct tty_port *tport = &sport->port.state->port;
 	struct dma_chan *chan = sport->dma_tx_chan;
 	unsigned long flags;
 
@@ -545,7 +539,7 @@ static void lpuart_dma_tx_complete(void *arg)
 	sport->dma_tx_in_progress = false;
 	uart_port_unlock_irqrestore(&sport->port, flags);
 
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+	if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)
 		uart_write_wakeup(&sport->port);
 
 	if (waitqueue_active(&sport->dma_wait)) {
@@ -756,8 +750,9 @@ static inline void lpuart_transmit_buffer(struct lpuart_port *sport)
 
 static inline void lpuart32_transmit_buffer(struct lpuart_port *sport)
 {
-	struct circ_buf *xmit = &sport->port.state->xmit;
+	struct tty_port *tport = &sport->port.state->port;
 	unsigned long txcnt;
+	unsigned char c;
 
 	if (sport->port.x_char) {
 		lpuart32_write(&sport->port, sport->port.x_char, UARTDATA);
@@ -774,18 +769,18 @@ static inline void lpuart32_transmit_buffer(struct lpuart_port *sport)
 	txcnt = lpuart32_read(&sport->port, UARTWATER);
 	txcnt = txcnt >> UARTWATER_TXCNT_OFF;
 	txcnt &= UARTWATER_COUNT_MASK;
-	while (!uart_circ_empty(xmit) && (txcnt < sport->txfifo_size)) {
-		lpuart32_write(&sport->port, xmit->buf[xmit->tail], UARTDATA);
-		uart_xmit_advance(&sport->port, 1);
+	while (txcnt < sport->txfifo_size &&
+			uart_fifo_get(&sport->port, &c)) {
+		lpuart32_write(&sport->port, c, UARTDATA);
 		txcnt = lpuart32_read(&sport->port, UARTWATER);
 		txcnt = txcnt >> UARTWATER_TXCNT_OFF;
 		txcnt &= UARTWATER_COUNT_MASK;
 	}
 
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+	if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)
 		uart_write_wakeup(&sport->port);
 
-	if (uart_circ_empty(xmit))
+	if (kfifo_is_empty(&tport->xmit_fifo))
 		lpuart32_stop_tx(&sport->port);
 }
 
@@ -2884,8 +2879,7 @@ static int lpuart_probe(struct platform_device *pdev)
 	sport->ipg_clk = devm_clk_get(&pdev->dev, "ipg");
 	if (IS_ERR(sport->ipg_clk)) {
 		ret = PTR_ERR(sport->ipg_clk);
-		dev_err(&pdev->dev, "failed to get uart ipg clk: %d\n", ret);
-		return ret;
+		return dev_err_probe(&pdev->dev, ret, "failed to get uart ipg clk\n");
 	}
 
 	sport->baud_clk = NULL;
@@ -2893,8 +2887,7 @@ static int lpuart_probe(struct platform_device *pdev)
 		sport->baud_clk = devm_clk_get(&pdev->dev, "baud");
 		if (IS_ERR(sport->baud_clk)) {
 			ret = PTR_ERR(sport->baud_clk);
-			dev_err(&pdev->dev, "failed to get uart baud clk: %d\n", ret);
-			return ret;
+			return dev_err_probe(&pdev->dev, ret, "failed to get uart baud clk\n");
 		}
 	}
 
diff --git a/drivers/tty/serial/icom.c b/drivers/tty/serial/icom.c
index a75eafbcbe..29e42831df 100644
--- a/drivers/tty/serial/icom.c
+++ b/drivers/tty/serial/icom.c
@@ -877,10 +877,10 @@ unlock:
 static int icom_write(struct uart_port *port)
 {
 	struct icom_port *icom_port = to_icom_port(port);
+	struct tty_port *tport = &port->state->port;
 	unsigned long data_count;
 	unsigned char cmdReg;
 	unsigned long offset;
-	int temp_tail = port->state->xmit.tail;
 
 	trace(icom_port, "WRITE", 0);
 
@@ -890,16 +890,8 @@ static int icom_write(struct uart_port *port)
 		return 0;
 	}
 
-	data_count = 0;
-	while ((port->state->xmit.head != temp_tail) &&
-	       (data_count <= XMIT_BUFF_SZ)) {
-
-		icom_port->xmit_buf[data_count++] =
-		    port->state->xmit.buf[temp_tail];
-
-		temp_tail++;
-		temp_tail &= (UART_XMIT_SIZE - 1);
-	}
+	data_count = kfifo_out_peek(&tport->xmit_fifo, icom_port->xmit_buf,
+			XMIT_BUFF_SZ);
 
 	if (data_count) {
 		icom_port->statStg->xmit[0].flags =
@@ -956,7 +948,8 @@ static inline void check_modem_status(struct icom_port *icom_port)
 
 static void xmit_interrupt(u16 port_int_reg, struct icom_port *icom_port)
 {
-	u16 count, i;
+	struct tty_port *tport = &icom_port->uart_port.state->port;
+	u16 count;
 
 	if (port_int_reg & (INT_XMIT_COMPLETED)) {
 		trace(icom_port, "XMIT_COMPLETE", 0);
@@ -968,13 +961,7 @@ static void xmit_interrupt(u16 port_int_reg, struct icom_port *icom_port)
 		count = le16_to_cpu(icom_port->statStg->xmit[0].leLength);
 		icom_port->uart_port.icount.tx += count;
 
-		for (i=0; i<count &&
-			!uart_circ_empty(&icom_port->uart_port.state->xmit); i++) {
-
-			icom_port->uart_port.state->xmit.tail++;
-			icom_port->uart_port.state->xmit.tail &=
-				(UART_XMIT_SIZE - 1);
-		}
+		kfifo_skip_count(&tport->xmit_fifo, count);
 
 		if (!icom_write(&icom_port->uart_port))
 			/* activate write queue */
diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index 8fde71138c..ff32cd2d28 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -8,6 +8,7 @@
  * Copyright (C) 2004 Pengutronix
  */
 
+#include <linux/circ_buf.h>
 #include <linux/module.h>
 #include <linux/ioport.h>
 #include <linux/init.h>
@@ -523,7 +524,8 @@ static void imx_uart_dma_tx(struct imx_port *sport);
 /* called with port.lock taken and irqs off */
 static inline void imx_uart_transmit_buffer(struct imx_port *sport)
 {
-	struct circ_buf *xmit = &sport->port.state->xmit;
+	struct tty_port *tport = &sport->port.state->port;
+	unsigned char c;
 
 	if (sport->port.x_char) {
 		/* Send next char */
@@ -533,7 +535,8 @@ static inline void imx_uart_transmit_buffer(struct imx_port *sport)
 		return;
 	}
 
-	if (uart_circ_empty(xmit) || uart_tx_stopped(&sport->port)) {
+	if (kfifo_is_empty(&tport->xmit_fifo) ||
+			uart_tx_stopped(&sport->port)) {
 		imx_uart_stop_tx(&sport->port);
 		return;
 	}
@@ -557,26 +560,22 @@ static inline void imx_uart_transmit_buffer(struct imx_port *sport)
 		return;
 	}
 
-	while (!uart_circ_empty(xmit) &&
-	       !(imx_uart_readl(sport, imx_uart_uts_reg(sport)) & UTS_TXFULL)) {
-		/* send xmit->buf[xmit->tail]
-		 * out the port here */
-		imx_uart_writel(sport, xmit->buf[xmit->tail], URTX0);
-		uart_xmit_advance(&sport->port, 1);
-	}
+	while (!(imx_uart_readl(sport, imx_uart_uts_reg(sport)) & UTS_TXFULL) &&
+			uart_fifo_get(&sport->port, &c))
+		imx_uart_writel(sport, c, URTX0);
 
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+	if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)
 		uart_write_wakeup(&sport->port);
 
-	if (uart_circ_empty(xmit))
+	if (kfifo_is_empty(&tport->xmit_fifo))
 		imx_uart_stop_tx(&sport->port);
 }
 
 static void imx_uart_dma_tx_callback(void *data)
 {
 	struct imx_port *sport = data;
+	struct tty_port *tport = &sport->port.state->port;
 	struct scatterlist *sgl = &sport->tx_sgl[0];
-	struct circ_buf *xmit = &sport->port.state->xmit;
 	unsigned long flags;
 	u32 ucr1;
 
@@ -594,10 +593,11 @@ static void imx_uart_dma_tx_callback(void *data)
 
 	sport->dma_is_txing = 0;
 
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+	if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)
 		uart_write_wakeup(&sport->port);
 
-	if (!uart_circ_empty(xmit) && !uart_tx_stopped(&sport->port))
+	if (!kfifo_is_empty(&tport->xmit_fifo) &&
+			!uart_tx_stopped(&sport->port))
 		imx_uart_dma_tx(sport);
 	else if (sport->port.rs485.flags & SER_RS485_ENABLED) {
 		u32 ucr4 = imx_uart_readl(sport, UCR4);
@@ -611,7 +611,7 @@ static void imx_uart_dma_tx_callback(void *data)
 /* called with port.lock taken and irqs off */
 static void imx_uart_dma_tx(struct imx_port *sport)
 {
-	struct circ_buf *xmit = &sport->port.state->xmit;
+	struct tty_port *tport = &sport->port.state->port;
 	struct scatterlist *sgl = sport->tx_sgl;
 	struct dma_async_tx_descriptor *desc;
 	struct dma_chan	*chan = sport->dma_chan_tx;
@@ -626,18 +626,10 @@ static void imx_uart_dma_tx(struct imx_port *sport)
 	ucr4 &= ~UCR4_TCEN;
 	imx_uart_writel(sport, ucr4, UCR4);
 
-	sport->tx_bytes = uart_circ_chars_pending(xmit);
-
-	if (xmit->tail < xmit->head || xmit->head == 0) {
-		sport->dma_tx_nents = 1;
-		sg_init_one(sgl, xmit->buf + xmit->tail, sport->tx_bytes);
-	} else {
-		sport->dma_tx_nents = 2;
-		sg_init_table(sgl, 2);
-		sg_set_buf(sgl, xmit->buf + xmit->tail,
-				UART_XMIT_SIZE - xmit->tail);
-		sg_set_buf(sgl + 1, xmit->buf, xmit->head);
-	}
+	sg_init_table(sgl, ARRAY_SIZE(sport->tx_sgl));
+	sport->tx_bytes = kfifo_len(&tport->xmit_fifo);
+	sport->dma_tx_nents = kfifo_dma_out_prepare(&tport->xmit_fifo, sgl,
+			ARRAY_SIZE(sport->tx_sgl), sport->tx_bytes);
 
 	ret = dma_map_sg(dev, sgl, sport->dma_tx_nents, DMA_TO_DEVICE);
 	if (ret == 0) {
@@ -655,8 +647,7 @@ static void imx_uart_dma_tx(struct imx_port *sport)
 	desc->callback = imx_uart_dma_tx_callback;
 	desc->callback_param = sport;
 
-	dev_dbg(dev, "TX: prepare to send %lu bytes by DMA.\n",
-			uart_circ_chars_pending(xmit));
+	dev_dbg(dev, "TX: prepare to send %u bytes by DMA.\n", sport->tx_bytes);
 
 	ucr1 = imx_uart_readl(sport, UCR1);
 	ucr1 |= UCR1_TXDMAEN;
@@ -673,9 +664,10 @@ static void imx_uart_dma_tx(struct imx_port *sport)
 static void imx_uart_start_tx(struct uart_port *port)
 {
 	struct imx_port *sport = (struct imx_port *)port;
+	struct tty_port *tport = &sport->port.state->port;
 	u32 ucr1;
 
-	if (!sport->port.x_char && uart_circ_empty(&port->state->xmit))
+	if (!sport->port.x_char && kfifo_is_empty(&tport->xmit_fifo))
 		return;
 
 	/*
@@ -751,7 +743,7 @@ static void imx_uart_start_tx(struct uart_port *port)
 			return;
 		}
 
-		if (!uart_circ_empty(&port->state->xmit) &&
+		if (!kfifo_is_empty(&tport->xmit_fifo) &&
 		    !uart_tx_stopped(port))
 			imx_uart_dma_tx(sport);
 		return;
diff --git a/drivers/tty/serial/ip22zilog.c b/drivers/tty/serial/ip22zilog.c
index 320b29cd46..c2cae50f06 100644
--- a/drivers/tty/serial/ip22zilog.c
+++ b/drivers/tty/serial/ip22zilog.c
@@ -355,7 +355,8 @@ static void ip22zilog_status_handle(struct uart_ip22zilog_port *up,
 static void ip22zilog_transmit_chars(struct uart_ip22zilog_port *up,
 				    struct zilog_channel *channel)
 {
-	struct circ_buf *xmit;
+	struct tty_port *tport;
+	unsigned char c;
 
 	if (ZS_IS_CONS(up)) {
 		unsigned char status = readb(&channel->control);
@@ -398,20 +399,18 @@ static void ip22zilog_transmit_chars(struct uart_ip22zilog_port *up,
 
 	if (up->port.state == NULL)
 		goto ack_tx_int;
-	xmit = &up->port.state->xmit;
-	if (uart_circ_empty(xmit))
-		goto ack_tx_int;
+	tport = &up->port.state->port;
 	if (uart_tx_stopped(&up->port))
 		goto ack_tx_int;
+	if (!uart_fifo_get(&up->port, &c))
+		goto ack_tx_int;
 
 	up->flags |= IP22ZILOG_FLAG_TX_ACTIVE;
-	writeb(xmit->buf[xmit->tail], &channel->data);
+	writeb(c, &channel->data);
 	ZSDELAY();
 	ZS_WSYNC(channel);
 
-	uart_xmit_advance(&up->port, 1);
-
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+	if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)
 		uart_write_wakeup(&up->port);
 
 	return;
@@ -600,17 +599,16 @@ static void ip22zilog_start_tx(struct uart_port *port)
 		port->icount.tx++;
 		port->x_char = 0;
 	} else {
-		struct circ_buf *xmit = &port->state->xmit;
+		struct tty_port *tport = &port->state->port;
+		unsigned char c;
 
-		if (uart_circ_empty(xmit))
+		if (!uart_fifo_get(port, &c))
 			return;
-		writeb(xmit->buf[xmit->tail], &channel->data);
+		writeb(c, &channel->data);
 		ZSDELAY();
 		ZS_WSYNC(channel);
 
-		uart_xmit_advance(port, 1);
-
-		if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+		if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)
 			uart_write_wakeup(&up->port);
 	}
 }
diff --git a/drivers/tty/serial/jsm/jsm_cls.c b/drivers/tty/serial/jsm/jsm_cls.c
index ddbd42c096..6e40792f92 100644
--- a/drivers/tty/serial/jsm/jsm_cls.c
+++ b/drivers/tty/serial/jsm/jsm_cls.c
@@ -443,20 +443,14 @@ static void cls_copy_data_from_uart_to_queue(struct jsm_channel *ch)
 
 static void cls_copy_data_from_queue_to_uart(struct jsm_channel *ch)
 {
-	u16 tail;
+	struct tty_port *tport;
 	int n;
-	int qlen;
 	u32 len_written = 0;
-	struct circ_buf *circ;
 
 	if (!ch)
 		return;
 
-	circ = &ch->uart_port.state->xmit;
-
-	/* No data to write to the UART */
-	if (uart_circ_empty(circ))
-		return;
+	tport = &ch->uart_port.state->port;
 
 	/* If port is "stopped", don't send any data to the UART */
 	if ((ch->ch_flags & CH_STOP) || (ch->ch_flags & CH_BREAK_SENDING))
@@ -467,29 +461,22 @@ static void cls_copy_data_from_queue_to_uart(struct jsm_channel *ch)
 		return;
 
 	n = 32;
+	while (n > 0) {
+		unsigned char c;
 
-	/* cache tail of queue */
-	tail = circ->tail & (UART_XMIT_SIZE - 1);
-	qlen = uart_circ_chars_pending(circ);
-
-	/* Find minimum of the FIFO space, versus queue length */
-	n = min(n, qlen);
+		if (!kfifo_get(&tport->xmit_fifo, &c))
+			break;
 
-	while (n > 0) {
-		writeb(circ->buf[tail], &ch->ch_cls_uart->txrx);
-		tail = (tail + 1) & (UART_XMIT_SIZE - 1);
+		writeb(c, &ch->ch_cls_uart->txrx);
 		n--;
 		ch->ch_txcount++;
 		len_written++;
 	}
 
-	/* Update the final tail */
-	circ->tail = tail & (UART_XMIT_SIZE - 1);
-
 	if (len_written > ch->ch_t_tlevel)
 		ch->ch_flags &= ~(CH_TX_FIFO_EMPTY | CH_TX_FIFO_LWM);
 
-	if (uart_circ_empty(circ))
+	if (kfifo_is_empty(&tport->xmit_fifo))
 		uart_write_wakeup(&ch->uart_port);
 }
 
diff --git a/drivers/tty/serial/jsm/jsm_neo.c b/drivers/tty/serial/jsm/jsm_neo.c
index 1fa10f1936..e8e13bf056 100644
--- a/drivers/tty/serial/jsm/jsm_neo.c
+++ b/drivers/tty/serial/jsm/jsm_neo.c
@@ -474,21 +474,21 @@ static void neo_copy_data_from_uart_to_queue(struct jsm_channel *ch)
 
 static void neo_copy_data_from_queue_to_uart(struct jsm_channel *ch)
 {
-	u16 head;
-	u16 tail;
+	struct tty_port *tport;
+	unsigned char *tail;
+	unsigned char c;
 	int n;
 	int s;
 	int qlen;
 	u32 len_written = 0;
-	struct circ_buf *circ;
 
 	if (!ch)
 		return;
 
-	circ = &ch->uart_port.state->xmit;
+	tport = &ch->uart_port.state->port;
 
 	/* No data to write to the UART */
-	if (uart_circ_empty(circ))
+	if (kfifo_is_empty(&tport->xmit_fifo))
 		return;
 
 	/* If port is "stopped", don't send any data to the UART */
@@ -504,10 +504,9 @@ static void neo_copy_data_from_queue_to_uart(struct jsm_channel *ch)
 		if (ch->ch_cached_lsr & UART_LSR_THRE) {
 			ch->ch_cached_lsr &= ~(UART_LSR_THRE);
 
-			writeb(circ->buf[circ->tail], &ch->ch_neo_uart->txrx);
-			jsm_dbg(WRITE, &ch->ch_bd->pci_dev,
-				"Tx data: %x\n", circ->buf[circ->tail]);
-			circ->tail = (circ->tail + 1) & (UART_XMIT_SIZE - 1);
+			WARN_ON_ONCE(!kfifo_get(&tport->xmit_fifo, &c));
+			writeb(c, &ch->ch_neo_uart->txrx);
+			jsm_dbg(WRITE, &ch->ch_bd->pci_dev, "Tx data: %x\n", c);
 			ch->ch_txcount++;
 		}
 		return;
@@ -520,38 +519,27 @@ static void neo_copy_data_from_queue_to_uart(struct jsm_channel *ch)
 		return;
 
 	n = UART_17158_TX_FIFOSIZE - ch->ch_t_tlevel;
-
-	/* cache head and tail of queue */
-	head = circ->head & (UART_XMIT_SIZE - 1);
-	tail = circ->tail & (UART_XMIT_SIZE - 1);
-	qlen = uart_circ_chars_pending(circ);
+	qlen = kfifo_len(&tport->xmit_fifo);
 
 	/* Find minimum of the FIFO space, versus queue length */
 	n = min(n, qlen);
 
 	while (n > 0) {
-
-		s = ((head >= tail) ? head : UART_XMIT_SIZE) - tail;
-		s = min(s, n);
-
+		s = kfifo_out_linear_ptr(&tport->xmit_fifo, &tail, n);
 		if (s <= 0)
 			break;
 
-		memcpy_toio(&ch->ch_neo_uart->txrxburst, circ->buf + tail, s);
-		/* Add and flip queue if needed */
-		tail = (tail + s) & (UART_XMIT_SIZE - 1);
+		memcpy_toio(&ch->ch_neo_uart->txrxburst, tail, s);
+		kfifo_skip_count(&tport->xmit_fifo, s);
 		n -= s;
 		ch->ch_txcount += s;
 		len_written += s;
 	}
 
-	/* Update the final tail */
-	circ->tail = tail & (UART_XMIT_SIZE - 1);
-
 	if (len_written >= ch->ch_t_tlevel)
 		ch->ch_flags &= ~(CH_TX_FIFO_EMPTY | CH_TX_FIFO_LWM);
 
-	if (uart_circ_empty(circ))
+	if (kfifo_is_empty(&tport->xmit_fifo))
 		uart_write_wakeup(&ch->uart_port);
 }
 
diff --git a/drivers/tty/serial/max3100.c b/drivers/tty/serial/max3100.c
index 3d2b83d6ab..fda63918d1 100644
--- a/drivers/tty/serial/max3100.c
+++ b/drivers/tty/serial/max3100.c
@@ -1,6 +1,5 @@
 // SPDX-License-Identifier: GPL-2.0+
 /*
- *
  *  Copyright (C) 2008 Christian Pellegrin <chripell@evolware.org>
  *
  * Notes: the MAX3100 doesn't provide an interrupt on CTS so we have
@@ -8,24 +7,6 @@
  * writing conf clears FIFO buffer and we cannot have this interrupt
  * always asking us for attention.
  *
- * Example platform data:
-
- static struct plat_max3100 max3100_plat_data = {
- .loopback = 0,
- .crystal = 0,
- .poll_time = 100,
- };
-
- static struct spi_board_info spi_board_info[] = {
- {
- .modalias	= "max3100",
- .platform_data	= &max3100_plat_data,
- .irq		= IRQ_EINT12,
- .max_speed_hz	= 5*1000*1000,
- .chip_select	= 0,
- },
- };
-
  * The initial minor number is 209 in the low-density serial port:
  * mknod /dev/ttyMAX0 c 204 209
  */
@@ -35,22 +16,24 @@
 /* 4 MAX3100s should be enough for everyone */
 #define MAX_MAX3100 4
 
+#include <linux/container_of.h>
 #include <linux/delay.h>
-#include <linux/slab.h>
 #include <linux/device.h>
+#include <linux/freezer.h>
+#include <linux/mod_devicetable.h>
 #include <linux/module.h>
+#include <linux/pm.h>
+#include <linux/property.h>
 #include <linux/serial_core.h>
 #include <linux/serial.h>
+#include <linux/slab.h>
 #include <linux/spi/spi.h>
-#include <linux/freezer.h>
-#include <linux/tty.h>
 #include <linux/tty_flip.h>
+#include <linux/tty.h>
 #include <linux/types.h>
 
 #include <asm/unaligned.h>
 
-#include <linux/serial_max3100.h>
-
 #define MAX3100_C    (1<<14)
 #define MAX3100_D    (0<<14)
 #define MAX3100_W    (1<<15)
@@ -113,10 +96,8 @@ struct max3100_port {
 #define MAX3100_7BIT 4
 	int rx_enabled;	        /* if we should rx chars */
 
-	int irq;		/* irq assigned to the max3100 */
-
 	int minor;		/* minor number */
-	int crystal;		/* 1 if 3.6864Mhz crystal 0 for 1.8432 */
+	int loopback_commit;	/* need to change loopback */
 	int loopback;		/* 1 if we are in loopback mode */
 
 	/* for handling irqs: need workqueue since we do spi_sync */
@@ -127,15 +108,14 @@ struct max3100_port {
 	/* need to know we are suspending to avoid deadlock on workqueue */
 	int suspending;
 
-	/* hook for suspending MAX3100 via dedicated pin */
-	void (*max3100_hw_suspend) (int suspend);
-
-	/* poll time (in ms) for ctrl lines */
-	int poll_time;
-	/* and its timer */
 	struct timer_list	timer;
 };
 
+static inline struct max3100_port *to_max3100_port(struct uart_port *port)
+{
+	return container_of(port, struct max3100_port, port);
+}
+
 static struct max3100_port *max3100s[MAX_MAX3100]; /* the chips */
 static DEFINE_MUTEX(max3100s_lock);		   /* race on probe */
 
@@ -173,24 +153,6 @@ static void max3100_calc_parity(struct max3100_port *s, u16 *c)
 		*c |= max3100_do_parity(s, *c) << 8;
 }
 
-static void max3100_work(struct work_struct *w);
-
-static void max3100_dowork(struct max3100_port *s)
-{
-	if (!s->force_end_work && !freezing(current) && !s->suspending)
-		queue_work(s->workqueue, &s->work);
-}
-
-static void max3100_timeout(struct timer_list *t)
-{
-	struct max3100_port *s = from_timer(s, t, timer);
-
-	if (s->port.state) {
-		max3100_dowork(s);
-		mod_timer(&s->timer, jiffies + s->poll_time);
-	}
-}
-
 static int max3100_sr(struct max3100_port *s, u16 tx, u16 *rx)
 {
 	struct spi_message message;
@@ -271,10 +233,11 @@ static int max3100_handlerx(struct max3100_port *s, u16 rx)
 static void max3100_work(struct work_struct *w)
 {
 	struct max3100_port *s = container_of(w, struct max3100_port, work);
+	struct tty_port *tport = &s->port.state->port;
+	unsigned char ch;
+	int conf, cconf, cloopback, crts;
 	int rxchars;
 	u16 tx, rx;
-	int conf, cconf, crts;
-	struct circ_buf *xmit = &s->port.state->xmit;
 
 	dev_dbg(&s->spi->dev, "%s\n", __func__);
 
@@ -284,11 +247,15 @@ static void max3100_work(struct work_struct *w)
 		conf = s->conf;
 		cconf = s->conf_commit;
 		s->conf_commit = 0;
+		cloopback = s->loopback_commit;
+		s->loopback_commit = 0;
 		crts = s->rts_commit;
 		s->rts_commit = 0;
 		spin_unlock(&s->conf_lock);
 		if (cconf)
 			max3100_sr(s, MAX3100_WC | conf, &rx);
+		if (cloopback)
+			max3100_sr(s, 0x4001, &rx);
 		if (crts) {
 			max3100_sr(s, MAX3100_WD | MAX3100_TE |
 				   (s->rts ? MAX3100_RTS : 0), &rx);
@@ -304,10 +271,9 @@ static void max3100_work(struct work_struct *w)
 				tx = s->port.x_char;
 				s->port.icount.tx++;
 				s->port.x_char = 0;
-			} else if (!uart_circ_empty(xmit) &&
-				   !uart_tx_stopped(&s->port)) {
-				tx = xmit->buf[xmit->tail];
-				uart_xmit_advance(&s->port, 1);
+			} else if (!uart_tx_stopped(&s->port) &&
+					uart_fifo_get(&s->port, &ch)) {
+				tx = ch;
 			}
 			if (tx != 0xffff) {
 				max3100_calc_parity(s, &tx);
@@ -321,19 +287,33 @@ static void max3100_work(struct work_struct *w)
 			tty_flip_buffer_push(&s->port.state->port);
 			rxchars = 0;
 		}
-		if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+		if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)
 			uart_write_wakeup(&s->port);
 
 	} while (!s->force_end_work &&
 		 !freezing(current) &&
 		 ((rx & MAX3100_R) ||
-		  (!uart_circ_empty(xmit) &&
+		  (!kfifo_is_empty(&tport->xmit_fifo) &&
 		   !uart_tx_stopped(&s->port))));
 
 	if (rxchars > 0)
 		tty_flip_buffer_push(&s->port.state->port);
 }
 
+static void max3100_dowork(struct max3100_port *s)
+{
+	if (!s->force_end_work && !freezing(current) && !s->suspending)
+		queue_work(s->workqueue, &s->work);
+}
+
+static void max3100_timeout(struct timer_list *t)
+{
+	struct max3100_port *s = from_timer(s, t, timer);
+
+	max3100_dowork(s);
+	mod_timer(&s->timer, jiffies + uart_poll_timeout(&s->port));
+}
+
 static irqreturn_t max3100_irq(int irqno, void *dev_id)
 {
 	struct max3100_port *s = dev_id;
@@ -346,20 +326,15 @@ static irqreturn_t max3100_irq(int irqno, void *dev_id)
 
 static void max3100_enable_ms(struct uart_port *port)
 {
-	struct max3100_port *s = container_of(port,
-					      struct max3100_port,
-					      port);
+	struct max3100_port *s = to_max3100_port(port);
 
-	if (s->poll_time > 0)
-		mod_timer(&s->timer, jiffies);
+	mod_timer(&s->timer, jiffies);
 	dev_dbg(&s->spi->dev, "%s\n", __func__);
 }
 
 static void max3100_start_tx(struct uart_port *port)
 {
-	struct max3100_port *s = container_of(port,
-					      struct max3100_port,
-					      port);
+	struct max3100_port *s = to_max3100_port(port);
 
 	dev_dbg(&s->spi->dev, "%s\n", __func__);
 
@@ -368,9 +343,7 @@ static void max3100_start_tx(struct uart_port *port)
 
 static void max3100_stop_rx(struct uart_port *port)
 {
-	struct max3100_port *s = container_of(port,
-					      struct max3100_port,
-					      port);
+	struct max3100_port *s = to_max3100_port(port);
 
 	dev_dbg(&s->spi->dev, "%s\n", __func__);
 
@@ -384,9 +357,7 @@ static void max3100_stop_rx(struct uart_port *port)
 
 static unsigned int max3100_tx_empty(struct uart_port *port)
 {
-	struct max3100_port *s = container_of(port,
-					      struct max3100_port,
-					      port);
+	struct max3100_port *s = to_max3100_port(port);
 
 	dev_dbg(&s->spi->dev, "%s\n", __func__);
 
@@ -397,9 +368,7 @@ static unsigned int max3100_tx_empty(struct uart_port *port)
 
 static unsigned int max3100_get_mctrl(struct uart_port *port)
 {
-	struct max3100_port *s = container_of(port,
-					      struct max3100_port,
-					      port);
+	struct max3100_port *s = to_max3100_port(port);
 
 	dev_dbg(&s->spi->dev, "%s\n", __func__);
 
@@ -411,21 +380,25 @@ static unsigned int max3100_get_mctrl(struct uart_port *port)
 
 static void max3100_set_mctrl(struct uart_port *port, unsigned int mctrl)
 {
-	struct max3100_port *s = container_of(port,
-					      struct max3100_port,
-					      port);
-	int rts;
+	struct max3100_port *s = to_max3100_port(port);
+	int loopback, rts;
 
 	dev_dbg(&s->spi->dev, "%s\n", __func__);
 
+	loopback = (mctrl & TIOCM_LOOP) > 0;
 	rts = (mctrl & TIOCM_RTS) > 0;
 
 	spin_lock(&s->conf_lock);
+	if (s->loopback != loopback) {
+		s->loopback = loopback;
+		s->loopback_commit = 1;
+	}
 	if (s->rts != rts) {
 		s->rts = rts;
 		s->rts_commit = 1;
-		max3100_dowork(s);
 	}
+	if (s->loopback_commit || s->rts_commit)
+		max3100_dowork(s);
 	spin_unlock(&s->conf_lock);
 }
 
@@ -433,10 +406,9 @@ static void
 max3100_set_termios(struct uart_port *port, struct ktermios *termios,
 		    const struct ktermios *old)
 {
-	struct max3100_port *s = container_of(port,
-					      struct max3100_port,
-					      port);
-	int baud = 0;
+	struct max3100_port *s = to_max3100_port(port);
+	unsigned int baud = port->uartclk / 16;
+	unsigned int baud230400 = (baud == 230400) ? 1 : 0;
 	unsigned cflag;
 	u32 param_new, param_mask, parity = 0;
 
@@ -449,40 +421,40 @@ max3100_set_termios(struct uart_port *port, struct ktermios *termios,
 	param_new = s->conf & MAX3100_BAUD;
 	switch (baud) {
 	case 300:
-		if (s->crystal)
+		if (baud230400)
 			baud = s->baud;
 		else
 			param_new = 15;
 		break;
 	case 600:
-		param_new = 14 + s->crystal;
+		param_new = 14 + baud230400;
 		break;
 	case 1200:
-		param_new = 13 + s->crystal;
+		param_new = 13 + baud230400;
 		break;
 	case 2400:
-		param_new = 12 + s->crystal;
+		param_new = 12 + baud230400;
 		break;
 	case 4800:
-		param_new = 11 + s->crystal;
+		param_new = 11 + baud230400;
 		break;
 	case 9600:
-		param_new = 10 + s->crystal;
+		param_new = 10 + baud230400;
 		break;
 	case 19200:
-		param_new = 9 + s->crystal;
+		param_new = 9 + baud230400;
 		break;
 	case 38400:
-		param_new = 8 + s->crystal;
+		param_new = 8 + baud230400;
 		break;
 	case 57600:
-		param_new = 1 + s->crystal;
+		param_new = 1 + baud230400;
 		break;
 	case 115200:
-		param_new = 0 + s->crystal;
+		param_new = 0 + baud230400;
 		break;
 	case 230400:
-		if (s->crystal)
+		if (baud230400)
 			param_new = 0;
 		else
 			baud = s->baud;
@@ -534,9 +506,7 @@ max3100_set_termios(struct uart_port *port, struct ktermios *termios,
 			MAX3100_STATUS_PE | MAX3100_STATUS_FE |
 			MAX3100_STATUS_OE;
 
-	if (s->poll_time > 0)
-		del_timer_sync(&s->timer);
-
+	del_timer_sync(&s->timer);
 	uart_update_timeout(port, termios->c_cflag, baud);
 
 	spin_lock(&s->conf_lock);
@@ -552,9 +522,8 @@ max3100_set_termios(struct uart_port *port, struct ktermios *termios,
 
 static void max3100_shutdown(struct uart_port *port)
 {
-	struct max3100_port *s = container_of(port,
-					      struct max3100_port,
-					      port);
+	struct max3100_port *s = to_max3100_port(port);
+	u16 rx;
 
 	dev_dbg(&s->spi->dev, "%s\n", __func__);
 
@@ -563,38 +532,29 @@ static void max3100_shutdown(struct uart_port *port)
 
 	s->force_end_work = 1;
 
-	if (s->poll_time > 0)
-		del_timer_sync(&s->timer);
+	del_timer_sync(&s->timer);
 
 	if (s->workqueue) {
 		destroy_workqueue(s->workqueue);
 		s->workqueue = NULL;
 	}
-	if (s->irq)
-		free_irq(s->irq, s);
+	if (port->irq)
+		free_irq(port->irq, s);
 
 	/* set shutdown mode to save power */
-	if (s->max3100_hw_suspend)
-		s->max3100_hw_suspend(1);
-	else  {
-		u16 tx, rx;
-
-		tx = MAX3100_WC | MAX3100_SHDN;
-		max3100_sr(s, tx, &rx);
-	}
+	max3100_sr(s, MAX3100_WC | MAX3100_SHDN, &rx);
 }
 
 static int max3100_startup(struct uart_port *port)
 {
-	struct max3100_port *s = container_of(port,
-					      struct max3100_port,
-					      port);
+	struct max3100_port *s = to_max3100_port(port);
 	char b[12];
+	int ret;
 
 	dev_dbg(&s->spi->dev, "%s\n", __func__);
 
 	s->conf = MAX3100_RM;
-	s->baud = s->crystal ? 230400 : 115200;
+	s->baud = port->uartclk / 16;
 	s->rx_enabled = 1;
 
 	if (s->suspending)
@@ -612,23 +572,15 @@ static int max3100_startup(struct uart_port *port)
 	}
 	INIT_WORK(&s->work, max3100_work);
 
-	if (request_irq(s->irq, max3100_irq,
-			IRQF_TRIGGER_FALLING, "max3100", s) < 0) {
-		dev_warn(&s->spi->dev, "cannot allocate irq %d\n", s->irq);
-		s->irq = 0;
+	ret = request_irq(port->irq, max3100_irq, IRQF_TRIGGER_FALLING, "max3100", s);
+	if (ret < 0) {
+		dev_warn(&s->spi->dev, "cannot allocate irq %d\n", port->irq);
+		port->irq = 0;
 		destroy_workqueue(s->workqueue);
 		s->workqueue = NULL;
 		return -EBUSY;
 	}
 
-	if (s->loopback) {
-		u16 tx, rx;
-		tx = 0x4001;
-		max3100_sr(s, tx, &rx);
-	}
-
-	if (s->max3100_hw_suspend)
-		s->max3100_hw_suspend(0);
 	s->conf_commit = 1;
 	max3100_dowork(s);
 	/* wait for clock to settle */
@@ -641,9 +593,7 @@ static int max3100_startup(struct uart_port *port)
 
 static const char *max3100_type(struct uart_port *port)
 {
-	struct max3100_port *s = container_of(port,
-					      struct max3100_port,
-					      port);
+	struct max3100_port *s = to_max3100_port(port);
 
 	dev_dbg(&s->spi->dev, "%s\n", __func__);
 
@@ -652,18 +602,14 @@ static const char *max3100_type(struct uart_port *port)
 
 static void max3100_release_port(struct uart_port *port)
 {
-	struct max3100_port *s = container_of(port,
-					      struct max3100_port,
-					      port);
+	struct max3100_port *s = to_max3100_port(port);
 
 	dev_dbg(&s->spi->dev, "%s\n", __func__);
 }
 
 static void max3100_config_port(struct uart_port *port, int flags)
 {
-	struct max3100_port *s = container_of(port,
-					      struct max3100_port,
-					      port);
+	struct max3100_port *s = to_max3100_port(port);
 
 	dev_dbg(&s->spi->dev, "%s\n", __func__);
 
@@ -674,9 +620,7 @@ static void max3100_config_port(struct uart_port *port, int flags)
 static int max3100_verify_port(struct uart_port *port,
 			       struct serial_struct *ser)
 {
-	struct max3100_port *s = container_of(port,
-					      struct max3100_port,
-					      port);
+	struct max3100_port *s = to_max3100_port(port);
 	int ret = -EINVAL;
 
 	dev_dbg(&s->spi->dev, "%s\n", __func__);
@@ -688,18 +632,14 @@ static int max3100_verify_port(struct uart_port *port,
 
 static void max3100_stop_tx(struct uart_port *port)
 {
-	struct max3100_port *s = container_of(port,
-					      struct max3100_port,
-					      port);
+	struct max3100_port *s = to_max3100_port(port);
 
 	dev_dbg(&s->spi->dev, "%s\n", __func__);
 }
 
 static int max3100_request_port(struct uart_port *port)
 {
-	struct max3100_port *s = container_of(port,
-					      struct max3100_port,
-					      port);
+	struct max3100_port *s = to_max3100_port(port);
 
 	dev_dbg(&s->spi->dev, "%s\n", __func__);
 	return 0;
@@ -707,9 +647,7 @@ static int max3100_request_port(struct uart_port *port)
 
 static void max3100_break_ctl(struct uart_port *port, int break_state)
 {
-	struct max3100_port *s = container_of(port,
-					      struct max3100_port,
-					      port);
+	struct max3100_port *s = to_max3100_port(port);
 
 	dev_dbg(&s->spi->dev, "%s\n", __func__);
 }
@@ -745,18 +683,17 @@ static int uart_driver_registered;
 
 static int max3100_probe(struct spi_device *spi)
 {
+	struct device *dev = &spi->dev;
 	int i, retval;
-	struct plat_max3100 *pdata;
-	u16 tx, rx;
+	u16 rx;
 
 	mutex_lock(&max3100s_lock);
 
 	if (!uart_driver_registered) {
 		retval = uart_register_driver(&max3100_uart_driver);
 		if (retval) {
-			printk(KERN_ERR "Couldn't register max3100 uart driver\n");
 			mutex_unlock(&max3100s_lock);
-			return retval;
+			return dev_err_probe(dev, retval, "Couldn't register max3100 uart driver\n");
 		}
 
 		uart_driver_registered = 1;
@@ -766,54 +703,39 @@ static int max3100_probe(struct spi_device *spi)
 		if (!max3100s[i])
 			break;
 	if (i == MAX_MAX3100) {
-		dev_warn(&spi->dev, "too many MAX3100 chips\n");
 		mutex_unlock(&max3100s_lock);
-		return -ENOMEM;
+		return dev_err_probe(dev, -ENOMEM, "too many MAX3100 chips\n");
 	}
 
 	max3100s[i] = kzalloc(sizeof(struct max3100_port), GFP_KERNEL);
 	if (!max3100s[i]) {
-		dev_warn(&spi->dev,
-			 "kmalloc for max3100 structure %d failed!\n", i);
 		mutex_unlock(&max3100s_lock);
 		return -ENOMEM;
 	}
 	max3100s[i]->spi = spi;
-	max3100s[i]->irq = spi->irq;
 	spin_lock_init(&max3100s[i]->conf_lock);
 	spi_set_drvdata(spi, max3100s[i]);
-	pdata = dev_get_platdata(&spi->dev);
-	max3100s[i]->crystal = pdata->crystal;
-	max3100s[i]->loopback = pdata->loopback;
-	max3100s[i]->poll_time = msecs_to_jiffies(pdata->poll_time);
-	if (pdata->poll_time > 0 && max3100s[i]->poll_time == 0)
-		max3100s[i]->poll_time = 1;
-	max3100s[i]->max3100_hw_suspend = pdata->max3100_hw_suspend;
 	max3100s[i]->minor = i;
 	timer_setup(&max3100s[i]->timer, max3100_timeout, 0);
 
 	dev_dbg(&spi->dev, "%s: adding port %d\n", __func__, i);
-	max3100s[i]->port.irq = max3100s[i]->irq;
-	max3100s[i]->port.uartclk = max3100s[i]->crystal ? 3686400 : 1843200;
+	max3100s[i]->port.irq = spi->irq;
 	max3100s[i]->port.fifosize = 16;
 	max3100s[i]->port.ops = &max3100_ops;
 	max3100s[i]->port.flags = UPF_SKIP_TEST | UPF_BOOT_AUTOCONF;
 	max3100s[i]->port.line = i;
 	max3100s[i]->port.type = PORT_MAX3100;
 	max3100s[i]->port.dev = &spi->dev;
+
+	/* Read clock frequency from a property, uart_add_one_port() will fail if it's not set */
+	device_property_read_u32(dev, "clock-frequency", &max3100s[i]->port.uartclk);
+
 	retval = uart_add_one_port(&max3100_uart_driver, &max3100s[i]->port);
 	if (retval < 0)
-		dev_warn(&spi->dev,
-			 "uart_add_one_port failed for line %d with error %d\n",
-			 i, retval);
+		dev_err_probe(dev, retval, "uart_add_one_port failed for line %d\n", i);
 
 	/* set shutdown mode to save power. Will be woken-up on open */
-	if (max3100s[i]->max3100_hw_suspend)
-		max3100s[i]->max3100_hw_suspend(1);
-	else {
-		tx = MAX3100_WC | MAX3100_SHDN;
-		max3100_sr(max3100s[i], tx, &rx);
-	}
+	max3100_sr(max3100s[i], MAX3100_WC | MAX3100_SHDN, &rx);
 	mutex_unlock(&max3100s_lock);
 	return 0;
 }
@@ -850,28 +772,20 @@ static void max3100_remove(struct spi_device *spi)
 	mutex_unlock(&max3100s_lock);
 }
 
-#ifdef CONFIG_PM_SLEEP
-
 static int max3100_suspend(struct device *dev)
 {
 	struct max3100_port *s = dev_get_drvdata(dev);
+	u16 rx;
 
 	dev_dbg(&s->spi->dev, "%s\n", __func__);
 
-	disable_irq(s->irq);
+	disable_irq(s->port.irq);
 
 	s->suspending = 1;
 	uart_suspend_port(&max3100_uart_driver, &s->port);
 
-	if (s->max3100_hw_suspend)
-		s->max3100_hw_suspend(1);
-	else {
-		/* no HW suspend, so do SW one */
-		u16 tx, rx;
-
-		tx = MAX3100_WC | MAX3100_SHDN;
-		max3100_sr(s, tx, &rx);
-	}
+	/* no HW suspend, so do SW one */
+	max3100_sr(s, MAX3100_WC | MAX3100_SHDN, &rx);
 	return 0;
 }
 
@@ -881,12 +795,10 @@ static int max3100_resume(struct device *dev)
 
 	dev_dbg(&s->spi->dev, "%s\n", __func__);
 
-	if (s->max3100_hw_suspend)
-		s->max3100_hw_suspend(0);
 	uart_resume_port(&max3100_uart_driver, &s->port);
 	s->suspending = 0;
 
-	enable_irq(s->irq);
+	enable_irq(s->port.irq);
 
 	s->conf_commit = 1;
 	if (s->workqueue)
@@ -895,20 +807,29 @@ static int max3100_resume(struct device *dev)
 	return 0;
 }
 
-static SIMPLE_DEV_PM_OPS(max3100_pm_ops, max3100_suspend, max3100_resume);
-#define MAX3100_PM_OPS (&max3100_pm_ops)
+static DEFINE_SIMPLE_DEV_PM_OPS(max3100_pm_ops, max3100_suspend, max3100_resume);
 
-#else
-#define MAX3100_PM_OPS NULL
-#endif
+static const struct spi_device_id max3100_spi_id[] = {
+	{ "max3100" },
+	{ }
+};
+MODULE_DEVICE_TABLE(spi, max3100_spi_id);
+
+static const struct of_device_id max3100_of_match[] = {
+	{ .compatible = "maxim,max3100" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, max3100_of_match);
 
 static struct spi_driver max3100_driver = {
 	.driver = {
 		.name		= "max3100",
-		.pm		= MAX3100_PM_OPS,
+		.of_match_table	= max3100_of_match,
+		.pm		= pm_sleep_ptr(&max3100_pm_ops),
 	},
 	.probe		= max3100_probe,
 	.remove		= max3100_remove,
+	.id_table	= max3100_spi_id,
 };
 
 module_spi_driver(max3100_driver);
@@ -916,4 +837,3 @@ module_spi_driver(max3100_driver);
 MODULE_DESCRIPTION("MAX3100 driver");
 MODULE_AUTHOR("Christian Pellegrin <chripell@evolware.org>");
 MODULE_LICENSE("GPL");
-MODULE_ALIAS("spi:max3100");
diff --git a/drivers/tty/serial/max310x.c b/drivers/tty/serial/max310x.c
index 14dd9cfaa9..35369a2f77 100644
--- a/drivers/tty/serial/max310x.c
+++ b/drivers/tty/serial/max310x.c
@@ -747,8 +747,9 @@ static void max310x_handle_rx(struct uart_port *port, unsigned int rxlen)
 
 static void max310x_handle_tx(struct uart_port *port)
 {
-	struct circ_buf *xmit = &port->state->xmit;
-	unsigned int txlen, to_send, until_end;
+	struct tty_port *tport = &port->state->port;
+	unsigned int txlen, to_send;
+	unsigned char *tail;
 
 	if (unlikely(port->x_char)) {
 		max310x_port_write(port, MAX310X_THR_REG, port->x_char);
@@ -757,32 +758,26 @@ static void max310x_handle_tx(struct uart_port *port)
 		return;
 	}
 
-	if (uart_circ_empty(xmit) || uart_tx_stopped(port))
+	if (kfifo_is_empty(&tport->xmit_fifo) || uart_tx_stopped(port))
 		return;
 
-	/* Get length of data pending in circular buffer */
-	to_send = uart_circ_chars_pending(xmit);
-	until_end = CIRC_CNT_TO_END(xmit->head, xmit->tail, UART_XMIT_SIZE);
-	if (likely(to_send)) {
+	/*
+	 * It's a circ buffer -- wrap around.
+	 * We could do that in one SPI transaction, but meh.
+	 */
+	while (!kfifo_is_empty(&tport->xmit_fifo)) {
 		/* Limit to space available in TX FIFO */
 		txlen = max310x_port_read(port, MAX310X_TXFIFOLVL_REG);
 		txlen = port->fifosize - txlen;
-		to_send = (to_send > txlen) ? txlen : to_send;
-
-		if (until_end < to_send) {
-			/*
-			 * It's a circ buffer -- wrap around.
-			 * We could do that in one SPI transaction, but meh.
-			 */
-			max310x_batch_write(port, xmit->buf + xmit->tail, until_end);
-			max310x_batch_write(port, xmit->buf, to_send - until_end);
-		} else {
-			max310x_batch_write(port, xmit->buf + xmit->tail, to_send);
-		}
+		if (!txlen)
+			break;
+
+		to_send = kfifo_out_linear_ptr(&tport->xmit_fifo, &tail, txlen);
+		max310x_batch_write(port, tail, to_send);
 		uart_xmit_advance(port, to_send);
 	}
 
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+	if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)
 		uart_write_wakeup(port);
 }
 
@@ -1478,7 +1473,7 @@ static struct regmap_config regcfg = {
 	.reg_bits = 8,
 	.val_bits = 8,
 	.write_flag_mask = MAX310X_WRITE_BIT,
-	.cache_type = REGCACHE_RBTREE,
+	.cache_type = REGCACHE_MAPLE,
 	.max_register = MAX310X_REG_1F,
 	.writeable_reg = max310x_reg_writeable,
 	.volatile_reg = max310x_reg_volatile,
@@ -1582,7 +1577,7 @@ static int max310x_i2c_extended_reg_enable(struct device *dev, bool enable)
 static struct regmap_config regcfg_i2c = {
 	.reg_bits = 8,
 	.val_bits = 8,
-	.cache_type = REGCACHE_RBTREE,
+	.cache_type = REGCACHE_MAPLE,
 	.writeable_reg = max310x_reg_writeable,
 	.volatile_reg = max310x_reg_volatile,
 	.precious_reg = max310x_reg_precious,
diff --git a/drivers/tty/serial/men_z135_uart.c b/drivers/tty/serial/men_z135_uart.c
index 8048fa542f..4bff422bb1 100644
--- a/drivers/tty/serial/men_z135_uart.c
+++ b/drivers/tty/serial/men_z135_uart.c
@@ -293,17 +293,14 @@ static void men_z135_handle_rx(struct men_z135_port *uart)
 static void men_z135_handle_tx(struct men_z135_port *uart)
 {
 	struct uart_port *port = &uart->port;
-	struct circ_buf *xmit = &port->state->xmit;
+	struct tty_port *tport = &port->state->port;
+	unsigned char *tail;
+	unsigned int n, txfree;
 	u32 txc;
 	u32 wptr;
 	int qlen;
-	int n;
-	int txfree;
-	int head;
-	int tail;
-	int s;
 
-	if (uart_circ_empty(xmit))
+	if (kfifo_is_empty(&tport->xmit_fifo))
 		goto out;
 
 	if (uart_tx_stopped(port))
@@ -313,7 +310,7 @@ static void men_z135_handle_tx(struct men_z135_port *uart)
 		goto out;
 
 	/* calculate bytes to copy */
-	qlen = uart_circ_chars_pending(xmit);
+	qlen = kfifo_len(&tport->xmit_fifo);
 	if (qlen <= 0)
 		goto out;
 
@@ -345,21 +342,18 @@ static void men_z135_handle_tx(struct men_z135_port *uart)
 	if (n <= 0)
 		goto irq_en;
 
-	head = xmit->head & (UART_XMIT_SIZE - 1);
-	tail = xmit->tail & (UART_XMIT_SIZE - 1);
-
-	s = ((head >= tail) ? head : UART_XMIT_SIZE) - tail;
-	n = min(n, s);
+	n = kfifo_out_linear_ptr(&tport->xmit_fifo, &tail,
+			min_t(unsigned int, UART_XMIT_SIZE, n));
+	memcpy_toio(port->membase + MEN_Z135_TX_RAM, tail, n);
 
-	memcpy_toio(port->membase + MEN_Z135_TX_RAM, &xmit->buf[xmit->tail], n);
 	iowrite32(n & 0x3ff, port->membase + MEN_Z135_TX_CTRL);
 	uart_xmit_advance(port, n);
 
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+	if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)
 		uart_write_wakeup(port);
 
 irq_en:
-	if (!uart_circ_empty(xmit))
+	if (!kfifo_is_empty(&tport->xmit_fifo))
 		men_z135_reg_set(uart, MEN_Z135_CONF_REG, MEN_Z135_IER_TXCIEN);
 	else
 		men_z135_reg_clr(uart, MEN_Z135_CONF_REG, MEN_Z135_IER_TXCIEN);
diff --git a/drivers/tty/serial/meson_uart.c b/drivers/tty/serial/meson_uart.c
index 6feac459c0..8eb586ac3b 100644
--- a/drivers/tty/serial/meson_uart.c
+++ b/drivers/tty/serial/meson_uart.c
@@ -141,8 +141,8 @@ static void meson_uart_shutdown(struct uart_port *port)
 
 static void meson_uart_start_tx(struct uart_port *port)
 {
-	struct circ_buf *xmit = &port->state->xmit;
-	unsigned int ch;
+	struct tty_port *tport = &port->state->port;
+	unsigned char ch;
 	u32 val;
 
 	if (uart_tx_stopped(port)) {
@@ -158,21 +158,19 @@ static void meson_uart_start_tx(struct uart_port *port)
 			continue;
 		}
 
-		if (uart_circ_empty(xmit))
+		if (!uart_fifo_get(port, &ch))
 			break;
 
-		ch = xmit->buf[xmit->tail];
 		writel(ch, port->membase + AML_UART_WFIFO);
-		uart_xmit_advance(port, 1);
 	}
 
-	if (!uart_circ_empty(xmit)) {
+	if (!kfifo_is_empty(&tport->xmit_fifo)) {
 		val = readl(port->membase + AML_UART_CONTROL);
 		val |= AML_UART_TX_INT_EN;
 		writel(val, port->membase + AML_UART_CONTROL);
 	}
 
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+	if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)
 		uart_write_wakeup(port);
 }
 
diff --git a/drivers/tty/serial/milbeaut_usio.c b/drivers/tty/serial/milbeaut_usio.c
index da4c6f7e2a..fb082ee73d 100644
--- a/drivers/tty/serial/milbeaut_usio.c
+++ b/drivers/tty/serial/milbeaut_usio.c
@@ -72,7 +72,7 @@ static void mlb_usio_stop_tx(struct uart_port *port)
 
 static void mlb_usio_tx_chars(struct uart_port *port)
 {
-	struct circ_buf *xmit = &port->state->xmit;
+	struct tty_port *tport = &port->state->port;
 	int count;
 
 	writew(readw(port->membase + MLB_USIO_REG_FCR) & ~MLB_USIO_FCR_FTIE,
@@ -87,7 +87,7 @@ static void mlb_usio_tx_chars(struct uart_port *port)
 		port->x_char = 0;
 		return;
 	}
-	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
+	if (kfifo_is_empty(&tport->xmit_fifo) || uart_tx_stopped(port)) {
 		mlb_usio_stop_tx(port);
 		return;
 	}
@@ -96,12 +96,13 @@ static void mlb_usio_tx_chars(struct uart_port *port)
 		(readw(port->membase + MLB_USIO_REG_FBYTE) & 0xff);
 
 	do {
-		writew(xmit->buf[xmit->tail], port->membase + MLB_USIO_REG_DR);
+		unsigned char ch;
 
-		uart_xmit_advance(port, 1);
-		if (uart_circ_empty(xmit))
+		if (!uart_fifo_get(port, &ch))
 			break;
 
+		writew(ch, port->membase + MLB_USIO_REG_DR);
+		port->icount.tx++;
 	} while (--count > 0);
 
 	writew(readw(port->membase + MLB_USIO_REG_FCR) & ~MLB_USIO_FCR_FDRQ,
@@ -110,10 +111,10 @@ static void mlb_usio_tx_chars(struct uart_port *port)
 	writeb(readb(port->membase + MLB_USIO_REG_SCR) | MLB_USIO_SCR_TBIE,
 	       port->membase + MLB_USIO_REG_SCR);
 
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+	if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)
 		uart_write_wakeup(port);
 
-	if (uart_circ_empty(xmit))
+	if (kfifo_is_empty(&tport->xmit_fifo))
 		mlb_usio_stop_tx(port);
 }
 
diff --git a/drivers/tty/serial/msm_serial.c b/drivers/tty/serial/msm_serial.c
index d27c4c8c84..0a9c5219df 100644
--- a/drivers/tty/serial/msm_serial.c
+++ b/drivers/tty/serial/msm_serial.c
@@ -161,11 +161,16 @@ enum {
 struct msm_dma {
 	struct dma_chan		*chan;
 	enum dma_data_direction dir;
-	dma_addr_t		phys;
-	unsigned char		*virt;
+	union {
+		struct {
+			dma_addr_t		phys;
+			unsigned char		*virt;
+			unsigned int		count;
+		} rx;
+		struct scatterlist tx_sg;
+	};
 	dma_cookie_t		cookie;
 	u32			enable_bit;
-	unsigned int		count;
 	struct dma_async_tx_descriptor	*desc;
 };
 
@@ -249,8 +254,12 @@ static void msm_stop_dma(struct uart_port *port, struct msm_dma *dma)
 	unsigned int mapped;
 	u32 val;
 
-	mapped = dma->count;
-	dma->count = 0;
+	if (dma->dir == DMA_TO_DEVICE) {
+		mapped = sg_dma_len(&dma->tx_sg);
+	} else {
+		mapped = dma->rx.count;
+		dma->rx.count = 0;
+	}
 
 	dmaengine_terminate_all(dma->chan);
 
@@ -265,8 +274,13 @@ static void msm_stop_dma(struct uart_port *port, struct msm_dma *dma)
 	val &= ~dma->enable_bit;
 	msm_write(port, val, UARTDM_DMEN);
 
-	if (mapped)
-		dma_unmap_single(dev, dma->phys, mapped, dma->dir);
+	if (mapped) {
+		if (dma->dir == DMA_TO_DEVICE) {
+			dma_unmap_sg(dev, &dma->tx_sg, 1, dma->dir);
+			sg_init_table(&dma->tx_sg, 1);
+		} else
+			dma_unmap_single(dev, dma->rx.phys, mapped, dma->dir);
+	}
 }
 
 static void msm_release_dma(struct msm_port *msm_port)
@@ -285,7 +299,7 @@ static void msm_release_dma(struct msm_port *msm_port)
 	if (dma->chan) {
 		msm_stop_dma(&msm_port->uart, dma);
 		dma_release_channel(dma->chan);
-		kfree(dma->virt);
+		kfree(dma->rx.virt);
 	}
 
 	memset(dma, 0, sizeof(*dma));
@@ -357,8 +371,8 @@ static void msm_request_rx_dma(struct msm_port *msm_port, resource_size_t base)
 
 	of_property_read_u32(dev->of_node, "qcom,rx-crci", &crci);
 
-	dma->virt = kzalloc(UARTDM_RX_SIZE, GFP_KERNEL);
-	if (!dma->virt)
+	dma->rx.virt = kzalloc(UARTDM_RX_SIZE, GFP_KERNEL);
+	if (!dma->rx.virt)
 		goto rel_rx;
 
 	memset(&conf, 0, sizeof(conf));
@@ -385,7 +399,7 @@ static void msm_request_rx_dma(struct msm_port *msm_port, resource_size_t base)
 
 	return;
 err:
-	kfree(dma->virt);
+	kfree(dma->rx.virt);
 rel_rx:
 	dma_release_channel(dma->chan);
 no_rx:
@@ -420,7 +434,7 @@ static void msm_start_tx(struct uart_port *port)
 	struct msm_dma *dma = &msm_port->tx_dma;
 
 	/* Already started in DMA mode */
-	if (dma->count)
+	if (sg_dma_len(&dma->tx_sg))
 		return;
 
 	msm_port->imr |= MSM_UART_IMR_TXLEV;
@@ -438,7 +452,7 @@ static void msm_complete_tx_dma(void *args)
 {
 	struct msm_port *msm_port = args;
 	struct uart_port *port = &msm_port->uart;
-	struct circ_buf *xmit = &port->state->xmit;
+	struct tty_port *tport = &port->state->port;
 	struct msm_dma *dma = &msm_port->tx_dma;
 	struct dma_tx_state state;
 	unsigned long flags;
@@ -448,12 +462,12 @@ static void msm_complete_tx_dma(void *args)
 	uart_port_lock_irqsave(port, &flags);
 
 	/* Already stopped */
-	if (!dma->count)
+	if (!sg_dma_len(&dma->tx_sg))
 		goto done;
 
 	dmaengine_tx_status(dma->chan, dma->cookie, &state);
 
-	dma_unmap_single(port->dev, dma->phys, dma->count, dma->dir);
+	dma_unmap_sg(port->dev, &dma->tx_sg, 1, dma->dir);
 
 	val = msm_read(port, UARTDM_DMEN);
 	val &= ~dma->enable_bit;
@@ -464,15 +478,15 @@ static void msm_complete_tx_dma(void *args)
 		msm_write(port, MSM_UART_CR_TX_ENABLE, MSM_UART_CR);
 	}
 
-	count = dma->count - state.residue;
+	count = sg_dma_len(&dma->tx_sg) - state.residue;
 	uart_xmit_advance(port, count);
-	dma->count = 0;
+	sg_init_table(&dma->tx_sg, 1);
 
 	/* Restore "Tx FIFO below watermark" interrupt */
 	msm_port->imr |= MSM_UART_IMR_TXLEV;
 	msm_write(port, msm_port->imr, MSM_UART_IMR);
 
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+	if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)
 		uart_write_wakeup(port);
 
 	msm_handle_tx(port);
@@ -482,22 +496,24 @@ done:
 
 static int msm_handle_tx_dma(struct msm_port *msm_port, unsigned int count)
 {
-	struct circ_buf *xmit = &msm_port->uart.state->xmit;
 	struct uart_port *port = &msm_port->uart;
+	struct tty_port *tport = &port->state->port;
 	struct msm_dma *dma = &msm_port->tx_dma;
-	void *cpu_addr;
+	unsigned int mapped;
 	int ret;
 	u32 val;
 
-	cpu_addr = &xmit->buf[xmit->tail];
+	sg_init_table(&dma->tx_sg, 1);
+	kfifo_dma_out_prepare(&tport->xmit_fifo, &dma->tx_sg, 1, count);
 
-	dma->phys = dma_map_single(port->dev, cpu_addr, count, dma->dir);
-	ret = dma_mapping_error(port->dev, dma->phys);
-	if (ret)
-		return ret;
+	mapped = dma_map_sg(port->dev, &dma->tx_sg, 1, dma->dir);
+	if (!mapped) {
+		ret = -EIO;
+		goto zero_sg;
+	}
 
-	dma->desc = dmaengine_prep_slave_single(dma->chan, dma->phys,
-						count, DMA_MEM_TO_DEV,
+	dma->desc = dmaengine_prep_slave_sg(dma->chan, &dma->tx_sg, 1,
+						DMA_MEM_TO_DEV,
 						DMA_PREP_INTERRUPT |
 						DMA_PREP_FENCE);
 	if (!dma->desc) {
@@ -520,8 +536,6 @@ static int msm_handle_tx_dma(struct msm_port *msm_port, unsigned int count)
 	msm_port->imr &= ~MSM_UART_IMR_TXLEV;
 	msm_write(port, msm_port->imr, MSM_UART_IMR);
 
-	dma->count = count;
-
 	val = msm_read(port, UARTDM_DMEN);
 	val |= dma->enable_bit;
 
@@ -536,7 +550,9 @@ static int msm_handle_tx_dma(struct msm_port *msm_port, unsigned int count)
 	dma_async_issue_pending(dma->chan);
 	return 0;
 unmap:
-	dma_unmap_single(port->dev, dma->phys, count, dma->dir);
+	dma_unmap_sg(port->dev, &dma->tx_sg, 1, dma->dir);
+zero_sg:
+	sg_init_table(&dma->tx_sg, 1);
 	return ret;
 }
 
@@ -553,7 +569,7 @@ static void msm_complete_rx_dma(void *args)
 	uart_port_lock_irqsave(port, &flags);
 
 	/* Already stopped */
-	if (!dma->count)
+	if (!dma->rx.count)
 		goto done;
 
 	val = msm_read(port, UARTDM_DMEN);
@@ -570,14 +586,14 @@ static void msm_complete_rx_dma(void *args)
 
 	port->icount.rx += count;
 
-	dma->count = 0;
+	dma->rx.count = 0;
 
-	dma_unmap_single(port->dev, dma->phys, UARTDM_RX_SIZE, dma->dir);
+	dma_unmap_single(port->dev, dma->rx.phys, UARTDM_RX_SIZE, dma->dir);
 
 	for (i = 0; i < count; i++) {
 		char flag = TTY_NORMAL;
 
-		if (msm_port->break_detected && dma->virt[i] == 0) {
+		if (msm_port->break_detected && dma->rx.virt[i] == 0) {
 			port->icount.brk++;
 			flag = TTY_BREAK;
 			msm_port->break_detected = false;
@@ -588,9 +604,9 @@ static void msm_complete_rx_dma(void *args)
 		if (!(port->read_status_mask & MSM_UART_SR_RX_BREAK))
 			flag = TTY_NORMAL;
 
-		sysrq = uart_prepare_sysrq_char(port, dma->virt[i]);
+		sysrq = uart_prepare_sysrq_char(port, dma->rx.virt[i]);
 		if (!sysrq)
-			tty_insert_flip_char(tport, dma->virt[i], flag);
+			tty_insert_flip_char(tport, dma->rx.virt[i], flag);
 	}
 
 	msm_start_rx_dma(msm_port);
@@ -614,13 +630,13 @@ static void msm_start_rx_dma(struct msm_port *msm_port)
 	if (!dma->chan)
 		return;
 
-	dma->phys = dma_map_single(uart->dev, dma->virt,
+	dma->rx.phys = dma_map_single(uart->dev, dma->rx.virt,
 				   UARTDM_RX_SIZE, dma->dir);
-	ret = dma_mapping_error(uart->dev, dma->phys);
+	ret = dma_mapping_error(uart->dev, dma->rx.phys);
 	if (ret)
 		goto sw_mode;
 
-	dma->desc = dmaengine_prep_slave_single(dma->chan, dma->phys,
+	dma->desc = dmaengine_prep_slave_single(dma->chan, dma->rx.phys,
 						UARTDM_RX_SIZE, DMA_DEV_TO_MEM,
 						DMA_PREP_INTERRUPT);
 	if (!dma->desc)
@@ -648,7 +664,7 @@ static void msm_start_rx_dma(struct msm_port *msm_port)
 
 	msm_write(uart, msm_port->imr, MSM_UART_IMR);
 
-	dma->count = UARTDM_RX_SIZE;
+	dma->rx.count = UARTDM_RX_SIZE;
 
 	dma_async_issue_pending(dma->chan);
 
@@ -668,7 +684,7 @@ static void msm_start_rx_dma(struct msm_port *msm_port)
 
 	return;
 unmap:
-	dma_unmap_single(uart->dev, dma->phys, UARTDM_RX_SIZE, dma->dir);
+	dma_unmap_single(uart->dev, dma->rx.phys, UARTDM_RX_SIZE, dma->dir);
 
 sw_mode:
 	/*
@@ -831,8 +847,8 @@ static void msm_handle_rx(struct uart_port *port)
 
 static void msm_handle_tx_pio(struct uart_port *port, unsigned int tx_count)
 {
-	struct circ_buf *xmit = &port->state->xmit;
 	struct msm_port *msm_port = to_msm_port(port);
+	struct tty_port *tport = &port->state->port;
 	unsigned int num_chars;
 	unsigned int tf_pointer = 0;
 	void __iomem *tf;
@@ -846,8 +862,7 @@ static void msm_handle_tx_pio(struct uart_port *port, unsigned int tx_count)
 		msm_reset_dm_count(port, tx_count);
 
 	while (tf_pointer < tx_count) {
-		int i;
-		char buf[4] = { 0 };
+		unsigned char buf[4] = { 0 };
 
 		if (!(msm_read(port, MSM_UART_SR) & MSM_UART_SR_TX_READY))
 			break;
@@ -858,26 +873,23 @@ static void msm_handle_tx_pio(struct uart_port *port, unsigned int tx_count)
 		else
 			num_chars = 1;
 
-		for (i = 0; i < num_chars; i++)
-			buf[i] = xmit->buf[xmit->tail + i];
-
+		num_chars = uart_fifo_out(port, buf, num_chars);
 		iowrite32_rep(tf, buf, 1);
-		uart_xmit_advance(port, num_chars);
 		tf_pointer += num_chars;
 	}
 
 	/* disable tx interrupts if nothing more to send */
-	if (uart_circ_empty(xmit))
+	if (kfifo_is_empty(&tport->xmit_fifo))
 		msm_stop_tx(port);
 
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+	if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)
 		uart_write_wakeup(port);
 }
 
 static void msm_handle_tx(struct uart_port *port)
 {
 	struct msm_port *msm_port = to_msm_port(port);
-	struct circ_buf *xmit = &msm_port->uart.state->xmit;
+	struct tty_port *tport = &port->state->port;
 	struct msm_dma *dma = &msm_port->tx_dma;
 	unsigned int pio_count, dma_count, dma_min;
 	char buf[4] = { 0 };
@@ -901,13 +913,13 @@ static void msm_handle_tx(struct uart_port *port)
 		return;
 	}
 
-	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
+	if (kfifo_is_empty(&tport->xmit_fifo) || uart_tx_stopped(port)) {
 		msm_stop_tx(port);
 		return;
 	}
 
-	pio_count = CIRC_CNT_TO_END(xmit->head, xmit->tail, UART_XMIT_SIZE);
-	dma_count = CIRC_CNT_TO_END(xmit->head, xmit->tail, UART_XMIT_SIZE);
+	dma_count = pio_count = kfifo_out_linear(&tport->xmit_fifo, NULL,
+			UART_XMIT_SIZE);
 
 	dma_min = 1;	/* Always DMA */
 	if (msm_port->is_uartdm > UARTDM_1P3) {
@@ -955,7 +967,7 @@ static irqreturn_t msm_uart_irq(int irq, void *dev_id)
 	}
 
 	if (misr & (MSM_UART_IMR_RXLEV | MSM_UART_IMR_RXSTALE)) {
-		if (dma->count) {
+		if (dma->rx.count) {
 			val = MSM_UART_CR_CMD_STALE_EVENT_DISABLE;
 			msm_write(port, val, MSM_UART_CR);
 			val = MSM_UART_CR_CMD_RESET_STALE_INT;
diff --git a/drivers/tty/serial/mvebu-uart.c b/drivers/tty/serial/mvebu-uart.c
index 0255646bc1..5de57b77ab 100644
--- a/drivers/tty/serial/mvebu-uart.c
+++ b/drivers/tty/serial/mvebu-uart.c
@@ -219,12 +219,10 @@ static void mvebu_uart_stop_tx(struct uart_port *port)
 static void mvebu_uart_start_tx(struct uart_port *port)
 {
 	unsigned int ctl;
-	struct circ_buf *xmit = &port->state->xmit;
+	unsigned char c;
 
-	if (IS_EXTENDED(port) && !uart_circ_empty(xmit)) {
-		writel(xmit->buf[xmit->tail], port->membase + UART_TSH(port));
-		uart_xmit_advance(port, 1);
-	}
+	if (IS_EXTENDED(port) && uart_fifo_get(port, &c))
+		writel(c, port->membase + UART_TSH(port));
 
 	ctl = readl(port->membase + UART_INTR(port));
 	ctl |= CTRL_TX_RDY_INT(port);
diff --git a/drivers/tty/serial/mxs-auart.c b/drivers/tty/serial/mxs-auart.c
index 1e8853eae5..a1c76565c3 100644
--- a/drivers/tty/serial/mxs-auart.c
+++ b/drivers/tty/serial/mxs-auart.c
@@ -517,7 +517,7 @@ static void mxs_auart_tx_chars(struct mxs_auart_port *s);
 static void dma_tx_callback(void *param)
 {
 	struct mxs_auart_port *s = param;
-	struct circ_buf *xmit = &s->port.state->xmit;
+	struct tty_port *tport = &s->port.state->port;
 
 	dma_unmap_sg(s->dev, &s->tx_sgl, 1, DMA_TO_DEVICE);
 
@@ -526,7 +526,7 @@ static void dma_tx_callback(void *param)
 	smp_mb__after_atomic();
 
 	/* wake up the possible processes. */
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+	if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)
 		uart_write_wakeup(&s->port);
 
 	mxs_auart_tx_chars(s);
@@ -568,33 +568,22 @@ static int mxs_auart_dma_tx(struct mxs_auart_port *s, int size)
 
 static void mxs_auart_tx_chars(struct mxs_auart_port *s)
 {
-	struct circ_buf *xmit = &s->port.state->xmit;
+	struct tty_port *tport = &s->port.state->port;
 	bool pending;
 	u8 ch;
 
 	if (auart_dma_enabled(s)) {
 		u32 i = 0;
-		int size;
 		void *buffer = s->tx_dma_buf;
 
 		if (test_and_set_bit(MXS_AUART_DMA_TX_SYNC, &s->flags))
 			return;
 
-		while (!uart_circ_empty(xmit) && !uart_tx_stopped(&s->port)) {
-			size = min_t(u32, UART_XMIT_SIZE - i,
-				     CIRC_CNT_TO_END(xmit->head,
-						     xmit->tail,
-						     UART_XMIT_SIZE));
-			memcpy(buffer + i, xmit->buf + xmit->tail, size);
-			xmit->tail = (xmit->tail + size) & (UART_XMIT_SIZE - 1);
-
-			i += size;
-			if (i >= UART_XMIT_SIZE)
-				break;
-		}
-
 		if (uart_tx_stopped(&s->port))
 			mxs_auart_stop_tx(&s->port);
+		else
+			i = kfifo_out(&tport->xmit_fifo, buffer,
+					UART_XMIT_SIZE);
 
 		if (i) {
 			mxs_auart_dma_tx(s, i);
diff --git a/drivers/tty/serial/omap-serial.c b/drivers/tty/serial/omap-serial.c
index 9be1c871cf..d7e172eeaa 100644
--- a/drivers/tty/serial/omap-serial.c
+++ b/drivers/tty/serial/omap-serial.c
@@ -1093,7 +1093,6 @@ static void __maybe_unused wait_for_xmitr(struct uart_omap_port *up)
 
 	/* Wait up to 1s for flow control if necessary */
 	if (up->port.flags & UPF_CONS_FLOW) {
-		tmout = 1000000;
 		for (tmout = 1000000; tmout; tmout--) {
 			unsigned int msr = serial_in(up, UART_MSR);
 
diff --git a/drivers/tty/serial/pch_uart.c b/drivers/tty/serial/pch_uart.c
index 89257cddf5..c7cee5fee6 100644
--- a/drivers/tty/serial/pch_uart.c
+++ b/drivers/tty/serial/pch_uart.c
@@ -808,7 +808,7 @@ static int dma_handle_rx(struct eg20t_port *priv)
 static unsigned int handle_tx(struct eg20t_port *priv)
 {
 	struct uart_port *port = &priv->port;
-	struct circ_buf *xmit = &port->state->xmit;
+	unsigned char ch;
 	int fifo_size;
 	int tx_empty;
 
@@ -830,9 +830,9 @@ static unsigned int handle_tx(struct eg20t_port *priv)
 		fifo_size--;
 	}
 
-	while (!uart_tx_stopped(port) && !uart_circ_empty(xmit) && fifo_size) {
-		iowrite8(xmit->buf[xmit->tail], priv->membase + PCH_UART_THR);
-		uart_xmit_advance(port, 1);
+	while (!uart_tx_stopped(port) && fifo_size &&
+			uart_fifo_get(port, &ch)) {
+		iowrite8(ch, priv->membase + PCH_UART_THR);
 		fifo_size--;
 		tx_empty = 0;
 	}
@@ -850,14 +850,14 @@ static unsigned int handle_tx(struct eg20t_port *priv)
 static unsigned int dma_handle_tx(struct eg20t_port *priv)
 {
 	struct uart_port *port = &priv->port;
-	struct circ_buf *xmit = &port->state->xmit;
+	struct tty_port *tport = &port->state->port;
 	struct scatterlist *sg;
 	int nent;
 	int fifo_size;
 	struct dma_async_tx_descriptor *desc;
+	unsigned int bytes, tail;
 	int num;
 	int i;
-	int bytes;
 	int size;
 	int rem;
 
@@ -886,7 +886,7 @@ static unsigned int dma_handle_tx(struct eg20t_port *priv)
 		fifo_size--;
 	}
 
-	bytes = CIRC_CNT_TO_END(xmit->head, xmit->tail, UART_XMIT_SIZE);
+	bytes = kfifo_out_linear(&tport->xmit_fifo, &tail, UART_XMIT_SIZE);
 	if (!bytes) {
 		dev_dbg(priv->port.dev, "%s 0 bytes return\n", __func__);
 		pch_uart_hal_disable_interrupt(priv, PCH_UART_HAL_TX_INT);
@@ -920,10 +920,10 @@ static unsigned int dma_handle_tx(struct eg20t_port *priv)
 
 	for (i = 0; i < num; i++, sg++) {
 		if (i == (num - 1))
-			sg_set_page(sg, virt_to_page(xmit->buf),
+			sg_set_page(sg, virt_to_page(tport->xmit_buf),
 				    rem, fifo_size * i);
 		else
-			sg_set_page(sg, virt_to_page(xmit->buf),
+			sg_set_page(sg, virt_to_page(tport->xmit_buf),
 				    size, fifo_size * i);
 	}
 
@@ -937,8 +937,7 @@ static unsigned int dma_handle_tx(struct eg20t_port *priv)
 	priv->nent = nent;
 
 	for (i = 0; i < nent; i++, sg++) {
-		sg->offset = (xmit->tail & (UART_XMIT_SIZE - 1)) +
-			      fifo_size * i;
+		sg->offset = tail + fifo_size * i;
 		sg_dma_address(sg) = (sg_dma_address(sg) &
 				    ~(UART_XMIT_SIZE - 1)) + sg->offset;
 		if (i == (nent - 1))
diff --git a/drivers/tty/serial/pic32_uart.c b/drivers/tty/serial/pic32_uart.c
index bbb46e6e98..261c8115a7 100644
--- a/drivers/tty/serial/pic32_uart.c
+++ b/drivers/tty/serial/pic32_uart.c
@@ -8,11 +8,11 @@
  *   Sorin-Andrei Pistirica <andrei.pistirica@microchip.com>
  */
 
+#include <linux/gpio/consumer.h>
 #include <linux/kernel.h>
 #include <linux/platform_device.h>
 #include <linux/of.h>
 #include <linux/of_irq.h>
-#include <linux/of_gpio.h>
 #include <linux/init.h>
 #include <linux/module.h>
 #include <linux/slab.h>
@@ -342,7 +342,7 @@ static void pic32_uart_do_rx(struct uart_port *port)
 static void pic32_uart_do_tx(struct uart_port *port)
 {
 	struct pic32_sport *sport = to_pic32_sport(port);
-	struct circ_buf *xmit = &port->state->xmit;
+	struct tty_port *tport = &port->state->port;
 	unsigned int max_count = PIC32_UART_TX_FIFO_DEPTH;
 
 	if (port->x_char) {
@@ -357,7 +357,7 @@ static void pic32_uart_do_tx(struct uart_port *port)
 		return;
 	}
 
-	if (uart_circ_empty(xmit))
+	if (kfifo_is_empty(&tport->xmit_fifo))
 		goto txq_empty;
 
 	/* keep stuffing chars into uart tx buffer
@@ -371,21 +371,20 @@ static void pic32_uart_do_tx(struct uart_port *port)
 	 */
 	while (!(PIC32_UART_STA_UTXBF &
 		pic32_uart_readl(sport, PIC32_UART_STA))) {
-		unsigned int c = xmit->buf[xmit->tail];
+		unsigned char c;
 
+		if (!uart_fifo_get(port, &c))
+			break;
 		pic32_uart_writel(sport, PIC32_UART_TX, c);
 
-		uart_xmit_advance(port, 1);
-		if (uart_circ_empty(xmit))
-			break;
 		if (--max_count == 0)
 			break;
 	}
 
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+	if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)
 		uart_write_wakeup(port);
 
-	if (uart_circ_empty(xmit))
+	if (kfifo_is_empty(&tport->xmit_fifo))
 		goto txq_empty;
 
 	return;
diff --git a/drivers/tty/serial/pmac_zilog.c b/drivers/tty/serial/pmac_zilog.c
index 92195f984d..8969b11cc0 100644
--- a/drivers/tty/serial/pmac_zilog.c
+++ b/drivers/tty/serial/pmac_zilog.c
@@ -333,7 +333,8 @@ static void pmz_status_handle(struct uart_pmac_port *uap)
 
 static void pmz_transmit_chars(struct uart_pmac_port *uap)
 {
-	struct circ_buf *xmit;
+	struct tty_port *tport;
+	unsigned char ch;
 
 	if (ZS_IS_CONS(uap)) {
 		unsigned char status = read_zsreg(uap, R0);
@@ -384,8 +385,8 @@ static void pmz_transmit_chars(struct uart_pmac_port *uap)
 
 	if (uap->port.state == NULL)
 		goto ack_tx_int;
-	xmit = &uap->port.state->xmit;
-	if (uart_circ_empty(xmit)) {
+	tport = &uap->port.state->port;
+	if (kfifo_is_empty(&tport->xmit_fifo)) {
 		uart_write_wakeup(&uap->port);
 		goto ack_tx_int;
 	}
@@ -393,12 +394,11 @@ static void pmz_transmit_chars(struct uart_pmac_port *uap)
 		goto ack_tx_int;
 
 	uap->flags |= PMACZILOG_FLAG_TX_ACTIVE;
-	write_zsdata(uap, xmit->buf[xmit->tail]);
+	WARN_ON(!uart_fifo_get(&uap->port, &ch));
+	write_zsdata(uap, ch);
 	zssync(uap);
 
-	uart_xmit_advance(&uap->port, 1);
-
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+	if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)
 		uart_write_wakeup(&uap->port);
 
 	return;
@@ -606,15 +606,15 @@ static void pmz_start_tx(struct uart_port *port)
 		port->icount.tx++;
 		port->x_char = 0;
 	} else {
-		struct circ_buf *xmit = &port->state->xmit;
+		struct tty_port *tport = &port->state->port;
+		unsigned char ch;
 
-		if (uart_circ_empty(xmit))
+		if (!uart_fifo_get(&uap->port, &ch))
 			return;
-		write_zsdata(uap, xmit->buf[xmit->tail]);
+		write_zsdata(uap, ch);
 		zssync(uap);
-		uart_xmit_advance(port, 1);
 
-		if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+		if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)
 			uart_write_wakeup(&uap->port);
 	}
 }
@@ -1681,7 +1681,7 @@ static void pmz_dispose_port(struct uart_pmac_port *uap)
 	memset(uap, 0, sizeof(struct uart_pmac_port));
 }
 
-static int __init pmz_attach(struct platform_device *pdev)
+static int pmz_attach(struct platform_device *pdev)
 {
 	struct uart_pmac_port *uap;
 	int i;
@@ -1700,7 +1700,7 @@ static int __init pmz_attach(struct platform_device *pdev)
 	return uart_add_one_port(&pmz_uart_reg, &uap->port);
 }
 
-static void __exit pmz_detach(struct platform_device *pdev)
+static void pmz_detach(struct platform_device *pdev)
 {
 	struct uart_pmac_port *uap = platform_get_drvdata(pdev);
 
@@ -1775,7 +1775,8 @@ static struct macio_driver pmz_driver = {
 #else
 
 static struct platform_driver pmz_driver = {
-	.remove_new	= __exit_p(pmz_detach),
+	.probe		= pmz_attach,
+	.remove_new	= pmz_detach,
 	.driver		= {
 		.name		= "scc",
 	},
@@ -1823,7 +1824,7 @@ static int __init init_pmz(void)
 #ifdef CONFIG_PPC_PMAC
 	return macio_register_driver(&pmz_driver);
 #else
-	return platform_driver_probe(&pmz_driver, pmz_attach);
+	return platform_driver_register(&pmz_driver);
 #endif
 }
 
diff --git a/drivers/tty/serial/qcom_geni_serial.c b/drivers/tty/serial/qcom_geni_serial.c
index f9f7ac1a10..69a632fefc 100644
--- a/drivers/tty/serial/qcom_geni_serial.c
+++ b/drivers/tty/serial/qcom_geni_serial.c
@@ -505,7 +505,7 @@ static void qcom_geni_serial_console_write(struct console *co, const char *s,
 		 */
 		qcom_geni_serial_poll_tx_done(uport);
 
-		if (!uart_circ_empty(&uport->state->xmit)) {
+		if (!kfifo_is_empty(&uport->state->port.xmit_fifo)) {
 			irq_en = readl(uport->membase + SE_GENI_M_IRQ_EN);
 			writel(irq_en | M_TX_FIFO_WATERMARK_EN,
 					uport->membase + SE_GENI_M_IRQ_EN);
@@ -620,22 +620,24 @@ static void qcom_geni_serial_stop_tx_dma(struct uart_port *uport)
 static void qcom_geni_serial_start_tx_dma(struct uart_port *uport)
 {
 	struct qcom_geni_serial_port *port = to_dev_port(uport);
-	struct circ_buf *xmit = &uport->state->xmit;
+	struct tty_port *tport = &uport->state->port;
 	unsigned int xmit_size;
+	u8 *tail;
 	int ret;
 
 	if (port->tx_dma_addr)
 		return;
 
-	if (uart_circ_empty(xmit))
+	if (kfifo_is_empty(&tport->xmit_fifo))
 		return;
 
-	xmit_size = CIRC_CNT_TO_END(xmit->head, xmit->tail, UART_XMIT_SIZE);
+	xmit_size = kfifo_out_linear_ptr(&tport->xmit_fifo, &tail,
+			UART_XMIT_SIZE);
 
 	qcom_geni_serial_setup_tx(uport, xmit_size);
 
-	ret = geni_se_tx_dma_prep(&port->se, &xmit->buf[xmit->tail],
-				  xmit_size, &port->tx_dma_addr);
+	ret = geni_se_tx_dma_prep(&port->se, tail, xmit_size,
+				  &port->tx_dma_addr);
 	if (ret) {
 		dev_err(uport->dev, "unable to start TX SE DMA: %d\n", ret);
 		qcom_geni_serial_stop_tx_dma(uport);
@@ -647,15 +649,25 @@ static void qcom_geni_serial_start_tx_dma(struct uart_port *uport)
 
 static void qcom_geni_serial_start_tx_fifo(struct uart_port *uport)
 {
+	unsigned char c;
 	u32 irq_en;
 
-	if (qcom_geni_serial_main_active(uport) ||
-	    !qcom_geni_serial_tx_empty(uport))
-		return;
+	/*
+	 * Start a new transfer in case the previous command was cancelled and
+	 * left data in the FIFO which may prevent the watermark interrupt
+	 * from triggering. Note that the stale data is discarded.
+	 */
+	if (!qcom_geni_serial_main_active(uport) &&
+	    !qcom_geni_serial_tx_empty(uport)) {
+		if (uart_fifo_out(uport, &c, 1) == 1) {
+			writel(M_CMD_DONE_EN, uport->membase + SE_GENI_M_IRQ_CLEAR);
+			qcom_geni_serial_setup_tx(uport, 1);
+			writel(c, uport->membase + SE_GENI_TX_FIFOn);
+		}
+	}
 
 	irq_en = readl(uport->membase +	SE_GENI_M_IRQ_EN);
 	irq_en |= M_TX_FIFO_WATERMARK_EN | M_CMD_DONE_EN;
-
 	writel(DEF_TX_WM, uport->membase + SE_GENI_TX_WATERMARK_REG);
 	writel(irq_en, uport->membase +	SE_GENI_M_IRQ_EN);
 }
@@ -663,13 +675,17 @@ static void qcom_geni_serial_start_tx_fifo(struct uart_port *uport)
 static void qcom_geni_serial_stop_tx_fifo(struct uart_port *uport)
 {
 	u32 irq_en;
-	struct qcom_geni_serial_port *port = to_dev_port(uport);
 
 	irq_en = readl(uport->membase + SE_GENI_M_IRQ_EN);
 	irq_en &= ~(M_CMD_DONE_EN | M_TX_FIFO_WATERMARK_EN);
 	writel(0, uport->membase + SE_GENI_TX_WATERMARK_REG);
 	writel(irq_en, uport->membase + SE_GENI_M_IRQ_EN);
-	/* Possible stop tx is called multiple times. */
+}
+
+static void qcom_geni_serial_cancel_tx_cmd(struct uart_port *uport)
+{
+	struct qcom_geni_serial_port *port = to_dev_port(uport);
+
 	if (!qcom_geni_serial_main_active(uport))
 		return;
 
@@ -682,6 +698,8 @@ static void qcom_geni_serial_stop_tx_fifo(struct uart_port *uport)
 		writel(M_CMD_ABORT_EN, uport->membase + SE_GENI_M_IRQ_CLEAR);
 	}
 	writel(M_CMD_CANCEL_EN, uport->membase + SE_GENI_M_IRQ_CLEAR);
+
+	port->tx_remaining = 0;
 }
 
 static void qcom_geni_serial_handle_rx_fifo(struct uart_port *uport, bool drop)
@@ -853,18 +871,14 @@ static void qcom_geni_serial_send_chunk_fifo(struct uart_port *uport,
 					     unsigned int chunk)
 {
 	struct qcom_geni_serial_port *port = to_dev_port(uport);
-	struct circ_buf *xmit = &uport->state->xmit;
-	unsigned int tx_bytes, c, remaining = chunk;
+	unsigned int tx_bytes, remaining = chunk;
 	u8 buf[BYTES_PER_FIFO_WORD];
 
 	while (remaining) {
 		memset(buf, 0, sizeof(buf));
 		tx_bytes = min(remaining, BYTES_PER_FIFO_WORD);
 
-		for (c = 0; c < tx_bytes ; c++) {
-			buf[c] = xmit->buf[xmit->tail];
-			uart_xmit_advance(uport, 1);
-		}
+		uart_fifo_out(uport, buf, tx_bytes);
 
 		iowrite32_rep(uport->membase + SE_GENI_TX_FIFOn, buf, 1);
 
@@ -877,7 +891,7 @@ static void qcom_geni_serial_handle_tx_fifo(struct uart_port *uport,
 					    bool done, bool active)
 {
 	struct qcom_geni_serial_port *port = to_dev_port(uport);
-	struct circ_buf *xmit = &uport->state->xmit;
+	struct tty_port *tport = &uport->state->port;
 	size_t avail;
 	size_t pending;
 	u32 status;
@@ -890,15 +904,19 @@ static void qcom_geni_serial_handle_tx_fifo(struct uart_port *uport,
 	if (active)
 		pending = port->tx_remaining;
 	else
-		pending = uart_circ_chars_pending(xmit);
+		pending = kfifo_len(&tport->xmit_fifo);
 
-	/* All data has been transmitted and acknowledged as received */
-	if (!pending && !status && done) {
+	/* All data has been transmitted or command has been cancelled */
+	if (!pending && done) {
 		qcom_geni_serial_stop_tx_fifo(uport);
 		goto out_write_wakeup;
 	}
 
-	avail = port->tx_fifo_depth - (status & TX_FIFO_WC);
+	if (active)
+		avail = port->tx_fifo_depth - (status & TX_FIFO_WC);
+	else
+		avail = port->tx_fifo_depth;
+
 	avail *= BYTES_PER_FIFO_WORD;
 
 	chunk = min(avail, pending);
@@ -933,24 +951,24 @@ out_write_wakeup:
 					uport->membase + SE_GENI_M_IRQ_EN);
 	}
 
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+	if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)
 		uart_write_wakeup(uport);
 }
 
 static void qcom_geni_serial_handle_tx_dma(struct uart_port *uport)
 {
 	struct qcom_geni_serial_port *port = to_dev_port(uport);
-	struct circ_buf *xmit = &uport->state->xmit;
+	struct tty_port *tport = &uport->state->port;
 
 	uart_xmit_advance(uport, port->tx_remaining);
 	geni_se_tx_dma_unprep(&port->se, port->tx_dma_addr, port->tx_remaining);
 	port->tx_dma_addr = 0;
 	port->tx_remaining = 0;
 
-	if (!uart_circ_empty(xmit))
+	if (!kfifo_is_empty(&tport->xmit_fifo))
 		qcom_geni_serial_start_tx_dma(uport);
 
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+	if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)
 		uart_write_wakeup(uport);
 }
 
@@ -1071,11 +1089,15 @@ static void qcom_geni_serial_shutdown(struct uart_port *uport)
 {
 	disable_irq(uport->irq);
 
-	if (uart_console(uport))
-		return;
-
 	qcom_geni_serial_stop_tx(uport);
 	qcom_geni_serial_stop_rx(uport);
+
+	qcom_geni_serial_cancel_tx_cmd(uport);
+}
+
+static void qcom_geni_serial_flush_buffer(struct uart_port *uport)
+{
+	qcom_geni_serial_cancel_tx_cmd(uport);
 }
 
 static int qcom_geni_serial_port_setup(struct uart_port *uport)
@@ -1534,6 +1556,7 @@ static const struct uart_ops qcom_geni_console_pops = {
 	.request_port = qcom_geni_serial_request_port,
 	.config_port = qcom_geni_serial_config_port,
 	.shutdown = qcom_geni_serial_shutdown,
+	.flush_buffer = qcom_geni_serial_flush_buffer,
 	.type = qcom_geni_serial_get_type,
 	.set_mctrl = qcom_geni_serial_set_mctrl,
 	.get_mctrl = qcom_geni_serial_get_mctrl,
diff --git a/drivers/tty/serial/rda-uart.c b/drivers/tty/serial/rda-uart.c
index 82def9b863..663e35e424 100644
--- a/drivers/tty/serial/rda-uart.c
+++ b/drivers/tty/serial/rda-uart.c
@@ -330,8 +330,8 @@ static void rda_uart_set_termios(struct uart_port *port,
 
 static void rda_uart_send_chars(struct uart_port *port)
 {
-	struct circ_buf *xmit = &port->state->xmit;
-	unsigned int ch;
+	struct tty_port *tport = &port->state->port;
+	unsigned char ch;
 	u32 val;
 
 	if (uart_tx_stopped(port))
@@ -347,19 +347,14 @@ static void rda_uart_send_chars(struct uart_port *port)
 		port->x_char = 0;
 	}
 
-	while (rda_uart_read(port, RDA_UART_STATUS) & RDA_UART_TX_FIFO_MASK) {
-		if (uart_circ_empty(xmit))
-			break;
-
-		ch = xmit->buf[xmit->tail];
+	while ((rda_uart_read(port, RDA_UART_STATUS) & RDA_UART_TX_FIFO_MASK) &&
+			uart_fifo_get(port, &ch))
 		rda_uart_write(port, ch, RDA_UART_RXTX_BUFFER);
-		uart_xmit_advance(port, 1);
-	}
 
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+	if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)
 		uart_write_wakeup(port);
 
-	if (!uart_circ_empty(xmit)) {
+	if (!kfifo_is_empty(&tport->xmit_fifo)) {
 		/* Re-enable Tx FIFO interrupt */
 		val = rda_uart_read(port, RDA_UART_IRQ_MASK);
 		val |= RDA_UART_TX_DATA_NEEDED;
diff --git a/drivers/tty/serial/samsung_tty.c b/drivers/tty/serial/samsung_tty.c
index a2d07e05c5..dc35eb77d2 100644
--- a/drivers/tty/serial/samsung_tty.c
+++ b/drivers/tty/serial/samsung_tty.c
@@ -329,7 +329,7 @@ static void s3c24xx_serial_tx_dma_complete(void *args)
 {
 	struct s3c24xx_uart_port *ourport = args;
 	struct uart_port *port = &ourport->port;
-	struct circ_buf *xmit = &port->state->xmit;
+	struct tty_port *tport = &port->state->port;
 	struct s3c24xx_uart_dma *dma = ourport->dma;
 	struct dma_tx_state state;
 	unsigned long flags;
@@ -348,7 +348,7 @@ static void s3c24xx_serial_tx_dma_complete(void *args)
 	uart_xmit_advance(port, count);
 	ourport->tx_in_progress = 0;
 
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+	if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)
 		uart_write_wakeup(port);
 
 	s3c24xx_serial_start_next_tx(ourport);
@@ -431,17 +431,15 @@ static void s3c24xx_serial_start_tx_pio(struct s3c24xx_uart_port *ourport)
 }
 
 static int s3c24xx_serial_start_tx_dma(struct s3c24xx_uart_port *ourport,
-				      unsigned int count)
+				      unsigned int count, unsigned int tail)
 {
-	struct uart_port *port = &ourport->port;
-	struct circ_buf *xmit = &port->state->xmit;
 	struct s3c24xx_uart_dma *dma = ourport->dma;
 
 	if (ourport->tx_mode != S3C24XX_TX_DMA)
 		enable_tx_dma(ourport);
 
 	dma->tx_size = count & ~(dma_get_cache_alignment() - 1);
-	dma->tx_transfer_addr = dma->tx_addr + xmit->tail;
+	dma->tx_transfer_addr = dma->tx_addr + tail;
 
 	dma_sync_single_for_device(dma->tx_chan->device->dev,
 				   dma->tx_transfer_addr, dma->tx_size,
@@ -468,11 +466,11 @@ static int s3c24xx_serial_start_tx_dma(struct s3c24xx_uart_port *ourport,
 static void s3c24xx_serial_start_next_tx(struct s3c24xx_uart_port *ourport)
 {
 	struct uart_port *port = &ourport->port;
-	struct circ_buf *xmit = &port->state->xmit;
-	unsigned long count;
+	struct tty_port *tport = &port->state->port;
+	unsigned int count, tail;
 
 	/* Get data size up to the end of buffer */
-	count = CIRC_CNT_TO_END(xmit->head, xmit->tail, UART_XMIT_SIZE);
+	count = kfifo_out_linear(&tport->xmit_fifo, &tail, UART_XMIT_SIZE);
 
 	if (!count) {
 		s3c24xx_serial_stop_tx(port);
@@ -481,16 +479,16 @@ static void s3c24xx_serial_start_next_tx(struct s3c24xx_uart_port *ourport)
 
 	if (!ourport->dma || !ourport->dma->tx_chan ||
 	    count < ourport->min_dma_size ||
-	    xmit->tail & (dma_get_cache_alignment() - 1))
+	    tail & (dma_get_cache_alignment() - 1))
 		s3c24xx_serial_start_tx_pio(ourport);
 	else
-		s3c24xx_serial_start_tx_dma(ourport, count);
+		s3c24xx_serial_start_tx_dma(ourport, count, tail);
 }
 
 static void s3c24xx_serial_start_tx(struct uart_port *port)
 {
 	struct s3c24xx_uart_port *ourport = to_ourport(port);
-	struct circ_buf *xmit = &port->state->xmit;
+	struct tty_port *tport = &port->state->port;
 
 	if (!ourport->tx_enabled) {
 		if (port->flags & UPF_CONS_FLOW)
@@ -502,7 +500,8 @@ static void s3c24xx_serial_start_tx(struct uart_port *port)
 	}
 
 	if (ourport->dma && ourport->dma->tx_chan) {
-		if (!uart_circ_empty(xmit) && !ourport->tx_in_progress)
+		if (!kfifo_is_empty(&tport->xmit_fifo) &&
+				!ourport->tx_in_progress)
 			s3c24xx_serial_start_next_tx(ourport);
 	}
 }
@@ -868,18 +867,19 @@ static irqreturn_t s3c24xx_serial_rx_irq(int irq, void *dev_id)
 static void s3c24xx_serial_tx_chars(struct s3c24xx_uart_port *ourport)
 {
 	struct uart_port *port = &ourport->port;
-	struct circ_buf *xmit = &port->state->xmit;
-	int count, dma_count = 0;
+	struct tty_port *tport = &port->state->port;
+	unsigned int count, dma_count = 0, tail;
 
-	count = CIRC_CNT_TO_END(xmit->head, xmit->tail, UART_XMIT_SIZE);
+	count = kfifo_out_linear(&tport->xmit_fifo, &tail, UART_XMIT_SIZE);
 
 	if (ourport->dma && ourport->dma->tx_chan &&
 	    count >= ourport->min_dma_size) {
 		int align = dma_get_cache_alignment() -
-			(xmit->tail & (dma_get_cache_alignment() - 1));
+			(tail & (dma_get_cache_alignment() - 1));
 		if (count - align >= ourport->min_dma_size) {
 			dma_count = count - align;
 			count = align;
+			tail += align;
 		}
 	}
 
@@ -894,7 +894,7 @@ static void s3c24xx_serial_tx_chars(struct s3c24xx_uart_port *ourport)
 	 * stopped, disable the uart and exit
 	 */
 
-	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
+	if (kfifo_is_empty(&tport->xmit_fifo) || uart_tx_stopped(port)) {
 		s3c24xx_serial_stop_tx(port);
 		return;
 	}
@@ -906,24 +906,25 @@ static void s3c24xx_serial_tx_chars(struct s3c24xx_uart_port *ourport)
 		dma_count = 0;
 	}
 
-	while (!uart_circ_empty(xmit) && count > 0) {
-		if (rd_regl(port, S3C2410_UFSTAT) & ourport->info->tx_fifofull)
+	while (!(rd_regl(port, S3C2410_UFSTAT) & ourport->info->tx_fifofull)) {
+		unsigned char ch;
+
+		if (!uart_fifo_get(port, &ch))
 			break;
 
-		wr_reg(port, S3C2410_UTXH, xmit->buf[xmit->tail]);
-		uart_xmit_advance(port, 1);
+		wr_reg(port, S3C2410_UTXH, ch);
 		count--;
 	}
 
 	if (!count && dma_count) {
-		s3c24xx_serial_start_tx_dma(ourport, dma_count);
+		s3c24xx_serial_start_tx_dma(ourport, dma_count, tail);
 		return;
 	}
 
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+	if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)
 		uart_write_wakeup(port);
 
-	if (uart_circ_empty(xmit))
+	if (kfifo_is_empty(&tport->xmit_fifo))
 		s3c24xx_serial_stop_tx(port);
 }
 
@@ -1118,7 +1119,8 @@ static int s3c24xx_serial_request_dma(struct s3c24xx_uart_port *p)
 
 	/* TX buffer */
 	dma->tx_addr = dma_map_single(dma->tx_chan->device->dev,
-				      p->port.state->xmit.buf, UART_XMIT_SIZE,
+				      p->port.state->port.xmit_buf,
+				      UART_XMIT_SIZE,
 				      DMA_TO_DEVICE);
 	if (dma_mapping_error(dma->tx_chan->device->dev, dma->tx_addr)) {
 		reason = "DMA mapping error for TX buffer";
diff --git a/drivers/tty/serial/sb1250-duart.c b/drivers/tty/serial/sb1250-duart.c
index dbec29d9a6..b4e1b90e59 100644
--- a/drivers/tty/serial/sb1250-duart.c
+++ b/drivers/tty/serial/sb1250-duart.c
@@ -382,7 +382,8 @@ static void sbd_receive_chars(struct sbd_port *sport)
 static void sbd_transmit_chars(struct sbd_port *sport)
 {
 	struct uart_port *uport = &sport->port;
-	struct circ_buf *xmit = &sport->port.state->xmit;
+	struct tty_port *tport = &sport->port.state->port;
+	unsigned char ch;
 	unsigned int mask;
 	int stop_tx;
 
@@ -395,19 +396,19 @@ static void sbd_transmit_chars(struct sbd_port *sport)
 	}
 
 	/* If nothing to do or stopped or hardware stopped.  */
-	stop_tx = (uart_circ_empty(xmit) || uart_tx_stopped(&sport->port));
+	stop_tx = uart_tx_stopped(&sport->port) ||
+		!uart_fifo_get(&sport->port, &ch);
 
 	/* Send char.  */
 	if (!stop_tx) {
-		write_sbdchn(sport, R_DUART_TX_HOLD, xmit->buf[xmit->tail]);
-		uart_xmit_advance(&sport->port, 1);
+		write_sbdchn(sport, R_DUART_TX_HOLD, ch);
 
-		if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+		if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)
 			uart_write_wakeup(&sport->port);
 	}
 
 	/* Are we are done?  */
-	if (stop_tx || uart_circ_empty(xmit)) {
+	if (stop_tx || kfifo_is_empty(&tport->xmit_fifo)) {
 		/* Disable tx interrupts.  */
 		mask = read_sbdshr(sport, R_DUART_IMRREG((uport->line) % 2));
 		mask &= ~M_DUART_IMR_TX;
diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c
index ace2c4b333..bf0065d1c8 100644
--- a/drivers/tty/serial/sc16is7xx.c
+++ b/drivers/tty/serial/sc16is7xx.c
@@ -1,19 +1,22 @@
 // SPDX-License-Identifier: GPL-2.0+
 /*
- * SC16IS7xx tty serial driver - Copyright (C) 2014 GridPoint
- * Author: Jon Ringle <jringle@gridpoint.com>
+ * SC16IS7xx tty serial driver - common code
  *
- *  Based on max310x.c, by Alexander Shiyan <shc_work@mail.ru>
+ * Copyright (C) 2014 GridPoint
+ * Author: Jon Ringle <jringle@gridpoint.com>
+ * Based on max310x.c, by Alexander Shiyan <shc_work@mail.ru>
  */
 
-#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+#undef DEFAULT_SYMBOL_NAMESPACE
+#define DEFAULT_SYMBOL_NAMESPACE SERIAL_NXP_SC16IS7XX
 
-#include <linux/bitops.h>
 #include <linux/clk.h>
 #include <linux/delay.h>
 #include <linux/device.h>
+#include <linux/export.h>
 #include <linux/gpio/driver.h>
-#include <linux/i2c.h>
+#include <linux/idr.h>
+#include <linux/kthread.h>
 #include <linux/mod_devicetable.h>
 #include <linux/module.h>
 #include <linux/property.h>
@@ -21,15 +24,15 @@
 #include <linux/sched.h>
 #include <linux/serial_core.h>
 #include <linux/serial.h>
+#include <linux/string.h>
 #include <linux/tty.h>
 #include <linux/tty_flip.h>
-#include <linux/spi/spi.h>
 #include <linux/uaccess.h>
 #include <linux/units.h>
 
-#define SC16IS7XX_NAME			"sc16is7xx"
+#include "sc16is7xx.h"
+
 #define SC16IS7XX_MAX_DEVS		8
-#define SC16IS7XX_MAX_PORTS		2 /* Maximum number of UART ports per IC. */
 
 /* SC16IS7XX register definitions */
 #define SC16IS7XX_RHR_REG		(0x00) /* RX FIFO */
@@ -302,16 +305,9 @@
 
 
 /* Misc definitions */
-#define SC16IS7XX_SPI_READ_BIT		BIT(7)
 #define SC16IS7XX_FIFO_SIZE		(64)
 #define SC16IS7XX_GPIOS_PER_BANK	4
 
-struct sc16is7xx_devtype {
-	char	name[10];
-	int	nr_gpio;
-	int	nr_uart;
-};
-
 #define SC16IS7XX_RECONF_MD		(1 << 0)
 #define SC16IS7XX_RECONF_IER		(1 << 1)
 #define SC16IS7XX_RECONF_RS485		(1 << 2)
@@ -349,7 +345,7 @@ struct sc16is7xx_port {
 	struct sc16is7xx_one		p[];
 };
 
-static DECLARE_BITMAP(sc16is7xx_lines, SC16IS7XX_MAX_DEVS);
+static DEFINE_IDA(sc16is7xx_lines);
 
 static struct uart_driver sc16is7xx_uart = {
 	.owner		= THIS_MODULE,
@@ -492,35 +488,40 @@ static void sc16is7xx_stop_rx(struct uart_port *port)
 	sc16is7xx_ier_clear(port, SC16IS7XX_IER_RDI_BIT);
 }
 
-static const struct sc16is7xx_devtype sc16is74x_devtype = {
+const struct sc16is7xx_devtype sc16is74x_devtype = {
 	.name		= "SC16IS74X",
 	.nr_gpio	= 0,
 	.nr_uart	= 1,
 };
+EXPORT_SYMBOL_GPL(sc16is74x_devtype);
 
-static const struct sc16is7xx_devtype sc16is750_devtype = {
+const struct sc16is7xx_devtype sc16is750_devtype = {
 	.name		= "SC16IS750",
 	.nr_gpio	= 8,
 	.nr_uart	= 1,
 };
+EXPORT_SYMBOL_GPL(sc16is750_devtype);
 
-static const struct sc16is7xx_devtype sc16is752_devtype = {
+const struct sc16is7xx_devtype sc16is752_devtype = {
 	.name		= "SC16IS752",
 	.nr_gpio	= 8,
 	.nr_uart	= 2,
 };
+EXPORT_SYMBOL_GPL(sc16is752_devtype);
 
-static const struct sc16is7xx_devtype sc16is760_devtype = {
+const struct sc16is7xx_devtype sc16is760_devtype = {
 	.name		= "SC16IS760",
 	.nr_gpio	= 8,
 	.nr_uart	= 1,
 };
+EXPORT_SYMBOL_GPL(sc16is760_devtype);
 
-static const struct sc16is7xx_devtype sc16is762_devtype = {
+const struct sc16is7xx_devtype sc16is762_devtype = {
 	.name		= "SC16IS762",
 	.nr_gpio	= 8,
 	.nr_uart	= 2,
 };
+EXPORT_SYMBOL_GPL(sc16is762_devtype);
 
 static bool sc16is7xx_regmap_volatile(struct device *dev, unsigned int reg)
 {
@@ -689,9 +690,9 @@ static void sc16is7xx_handle_rx(struct uart_port *port, unsigned int rxlen,
 static void sc16is7xx_handle_tx(struct uart_port *port)
 {
 	struct sc16is7xx_port *s = dev_get_drvdata(port->dev);
-	struct circ_buf *xmit = &port->state->xmit;
-	unsigned int txlen, to_send, i;
+	struct tty_port *tport = &port->state->port;
 	unsigned long flags;
+	unsigned int txlen;
 
 	if (unlikely(port->x_char)) {
 		sc16is7xx_port_write(port, SC16IS7XX_THR_REG, port->x_char);
@@ -700,40 +701,30 @@ static void sc16is7xx_handle_tx(struct uart_port *port)
 		return;
 	}
 
-	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
+	if (kfifo_is_empty(&tport->xmit_fifo) || uart_tx_stopped(port)) {
 		uart_port_lock_irqsave(port, &flags);
 		sc16is7xx_stop_tx(port);
 		uart_port_unlock_irqrestore(port, flags);
 		return;
 	}
 
-	/* Get length of data pending in circular buffer */
-	to_send = uart_circ_chars_pending(xmit);
-	if (likely(to_send)) {
-		/* Limit to space available in TX FIFO */
-		txlen = sc16is7xx_port_read(port, SC16IS7XX_TXLVL_REG);
-		if (txlen > SC16IS7XX_FIFO_SIZE) {
-			dev_err_ratelimited(port->dev,
-				"chip reports %d free bytes in TX fifo, but it only has %d",
-				txlen, SC16IS7XX_FIFO_SIZE);
-			txlen = 0;
-		}
-		to_send = (to_send > txlen) ? txlen : to_send;
-
-		/* Convert to linear buffer */
-		for (i = 0; i < to_send; ++i) {
-			s->buf[i] = xmit->buf[xmit->tail];
-			uart_xmit_advance(port, 1);
-		}
-
-		sc16is7xx_fifo_write(port, s->buf, to_send);
+	/* Limit to space available in TX FIFO */
+	txlen = sc16is7xx_port_read(port, SC16IS7XX_TXLVL_REG);
+	if (txlen > SC16IS7XX_FIFO_SIZE) {
+		dev_err_ratelimited(port->dev,
+			"chip reports %d free bytes in TX fifo, but it only has %d",
+			txlen, SC16IS7XX_FIFO_SIZE);
+		txlen = 0;
 	}
 
+	txlen = uart_fifo_out(port, s->buf, txlen);
+	sc16is7xx_fifo_write(port, s->buf, txlen);
+
 	uart_port_lock_irqsave(port, &flags);
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+	if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)
 		uart_write_wakeup(port);
 
-	if (uart_circ_empty(xmit))
+	if (kfifo_is_empty(&tport->xmit_fifo))
 		sc16is7xx_stop_tx(port);
 	else
 		sc16is7xx_ier_set(port, SC16IS7XX_IER_THRI_BIT);
@@ -1476,15 +1467,15 @@ static const struct serial_rs485 sc16is7xx_rs485_supported = {
 	.delay_rts_after_send = 1,	/* Not supported but keep returning -EINVAL */
 };
 
-static int sc16is7xx_probe(struct device *dev,
-			   const struct sc16is7xx_devtype *devtype,
-			   struct regmap *regmaps[], int irq)
+int sc16is7xx_probe(struct device *dev, const struct sc16is7xx_devtype *devtype,
+		    struct regmap *regmaps[], int irq)
 {
 	unsigned long freq = 0, *pfreq = dev_get_platdata(dev);
 	unsigned int val;
 	u32 uartclk = 0;
 	int i, ret;
 	struct sc16is7xx_port *s;
+	bool port_registered[SC16IS7XX_MAX_PORTS];
 
 	for (i = 0; i < devtype->nr_uart; i++)
 		if (IS_ERR(regmaps[i]))
@@ -1549,13 +1540,19 @@ static int sc16is7xx_probe(struct device *dev,
 	regmap_write(regmaps[0], SC16IS7XX_IOCONTROL_REG,
 		     SC16IS7XX_IOCONTROL_SRESET_BIT);
 
+	/* Mark each port line and status as uninitialised. */
 	for (i = 0; i < devtype->nr_uart; ++i) {
-		s->p[i].port.line = find_first_zero_bit(sc16is7xx_lines,
-							SC16IS7XX_MAX_DEVS);
-		if (s->p[i].port.line >= SC16IS7XX_MAX_DEVS) {
-			ret = -ERANGE;
+		s->p[i].port.line = SC16IS7XX_MAX_DEVS;
+		port_registered[i] = false;
+	}
+
+	for (i = 0; i < devtype->nr_uart; ++i) {
+		ret = ida_alloc_max(&sc16is7xx_lines,
+				    SC16IS7XX_MAX_DEVS - 1, GFP_KERNEL);
+		if (ret < 0)
 			goto out_ports;
-		}
+
+		s->p[i].port.line = ret;
 
 		/* Initialize port data */
 		s->p[i].port.dev	= dev;
@@ -1601,7 +1598,7 @@ static int sc16is7xx_probe(struct device *dev,
 		if (ret)
 			goto out_ports;
 
-		set_bit(s->p[i].port.line, sc16is7xx_lines);
+		port_registered[i] = true;
 
 		/* Enable EFR */
 		sc16is7xx_port_write(&s->p[i].port, SC16IS7XX_LCR_REG,
@@ -1659,9 +1656,12 @@ static int sc16is7xx_probe(struct device *dev,
 #endif
 
 out_ports:
-	for (i = 0; i < devtype->nr_uart; i++)
-		if (test_and_clear_bit(s->p[i].port.line, sc16is7xx_lines))
+	for (i = 0; i < devtype->nr_uart; i++) {
+		if (s->p[i].port.line < SC16IS7XX_MAX_DEVS)
+			ida_free(&sc16is7xx_lines, s->p[i].port.line);
+		if (port_registered[i])
 			uart_remove_one_port(&sc16is7xx_uart, &s->p[i].port);
+	}
 
 	kthread_stop(s->kworker_task);
 
@@ -1670,8 +1670,9 @@ out_clk:
 
 	return ret;
 }
+EXPORT_SYMBOL_GPL(sc16is7xx_probe);
 
-static void sc16is7xx_remove(struct device *dev)
+void sc16is7xx_remove(struct device *dev)
 {
 	struct sc16is7xx_port *s = dev_get_drvdata(dev);
 	int i;
@@ -1683,8 +1684,8 @@ static void sc16is7xx_remove(struct device *dev)
 
 	for (i = 0; i < s->devtype->nr_uart; i++) {
 		kthread_cancel_delayed_work_sync(&s->p[i].ms_work);
-		if (test_and_clear_bit(s->p[i].port.line, sc16is7xx_lines))
-			uart_remove_one_port(&sc16is7xx_uart, &s->p[i].port);
+		ida_free(&sc16is7xx_lines, s->p[i].port.line);
+		uart_remove_one_port(&sc16is7xx_uart, &s->p[i].port);
 		sc16is7xx_power(&s->p[i].port, 0);
 	}
 
@@ -1693,8 +1694,9 @@ static void sc16is7xx_remove(struct device *dev)
 
 	clk_disable_unprepare(s->clk);
 }
+EXPORT_SYMBOL_GPL(sc16is7xx_remove);
 
-static const struct of_device_id __maybe_unused sc16is7xx_dt_ids[] = {
+const struct of_device_id __maybe_unused sc16is7xx_dt_ids[] = {
 	{ .compatible = "nxp,sc16is740",	.data = &sc16is74x_devtype, },
 	{ .compatible = "nxp,sc16is741",	.data = &sc16is74x_devtype, },
 	{ .compatible = "nxp,sc16is750",	.data = &sc16is750_devtype, },
@@ -1703,13 +1705,14 @@ static const struct of_device_id __maybe_unused sc16is7xx_dt_ids[] = {
 	{ .compatible = "nxp,sc16is762",	.data = &sc16is762_devtype, },
 	{ }
 };
+EXPORT_SYMBOL_GPL(sc16is7xx_dt_ids);
 MODULE_DEVICE_TABLE(of, sc16is7xx_dt_ids);
 
-static struct regmap_config regcfg = {
+const struct regmap_config sc16is7xx_regcfg = {
 	.reg_bits = 5,
 	.pad_bits = 3,
 	.val_bits = 8,
-	.cache_type = REGCACHE_RBTREE,
+	.cache_type = REGCACHE_MAPLE,
 	.volatile_reg = sc16is7xx_regmap_volatile,
 	.precious_reg = sc16is7xx_regmap_precious,
 	.writeable_noinc_reg = sc16is7xx_regmap_noinc,
@@ -1718,8 +1721,9 @@ static struct regmap_config regcfg = {
 	.max_raw_write = SC16IS7XX_FIFO_SIZE,
 	.max_register = SC16IS7XX_EFCR_REG,
 };
+EXPORT_SYMBOL_GPL(sc16is7xx_regcfg);
 
-static const char *sc16is7xx_regmap_name(u8 port_id)
+const char *sc16is7xx_regmap_name(u8 port_id)
 {
 	switch (port_id) {
 	case 0:	return "port0";
@@ -1729,184 +1733,27 @@ static const char *sc16is7xx_regmap_name(u8 port_id)
 		return NULL;
 	}
 }
+EXPORT_SYMBOL_GPL(sc16is7xx_regmap_name);
 
-static unsigned int sc16is7xx_regmap_port_mask(unsigned int port_id)
+unsigned int sc16is7xx_regmap_port_mask(unsigned int port_id)
 {
 	/* CH1,CH0 are at bits 2:1. */
 	return port_id << 1;
 }
-
-#ifdef CONFIG_SERIAL_SC16IS7XX_SPI
-static int sc16is7xx_spi_probe(struct spi_device *spi)
-{
-	const struct sc16is7xx_devtype *devtype;
-	struct regmap *regmaps[SC16IS7XX_MAX_PORTS];
-	unsigned int i;
-	int ret;
-
-	/* Setup SPI bus */
-	spi->bits_per_word	= 8;
-	/* For all variants, only mode 0 is supported */
-	if ((spi->mode & SPI_MODE_X_MASK) != SPI_MODE_0)
-		return dev_err_probe(&spi->dev, -EINVAL, "Unsupported SPI mode\n");
-
-	spi->mode		= spi->mode ? : SPI_MODE_0;
-	spi->max_speed_hz	= spi->max_speed_hz ? : 4 * HZ_PER_MHZ;
-	ret = spi_setup(spi);
-	if (ret)
-		return ret;
-
-	devtype = spi_get_device_match_data(spi);
-	if (!devtype)
-		return dev_err_probe(&spi->dev, -ENODEV, "Failed to match device\n");
-
-	for (i = 0; i < devtype->nr_uart; i++) {
-		regcfg.name = sc16is7xx_regmap_name(i);
-		/*
-		 * If read_flag_mask is 0, the regmap code sets it to a default
-		 * of 0x80. Since we specify our own mask, we must add the READ
-		 * bit ourselves:
-		 */
-		regcfg.read_flag_mask = sc16is7xx_regmap_port_mask(i) |
-			SC16IS7XX_SPI_READ_BIT;
-		regcfg.write_flag_mask = sc16is7xx_regmap_port_mask(i);
-		regmaps[i] = devm_regmap_init_spi(spi, &regcfg);
-	}
-
-	return sc16is7xx_probe(&spi->dev, devtype, regmaps, spi->irq);
-}
-
-static void sc16is7xx_spi_remove(struct spi_device *spi)
-{
-	sc16is7xx_remove(&spi->dev);
-}
-
-static const struct spi_device_id sc16is7xx_spi_id_table[] = {
-	{ "sc16is74x",	(kernel_ulong_t)&sc16is74x_devtype, },
-	{ "sc16is740",	(kernel_ulong_t)&sc16is74x_devtype, },
-	{ "sc16is741",	(kernel_ulong_t)&sc16is74x_devtype, },
-	{ "sc16is750",	(kernel_ulong_t)&sc16is750_devtype, },
-	{ "sc16is752",	(kernel_ulong_t)&sc16is752_devtype, },
-	{ "sc16is760",	(kernel_ulong_t)&sc16is760_devtype, },
-	{ "sc16is762",	(kernel_ulong_t)&sc16is762_devtype, },
-	{ }
-};
-
-MODULE_DEVICE_TABLE(spi, sc16is7xx_spi_id_table);
-
-static struct spi_driver sc16is7xx_spi_uart_driver = {
-	.driver = {
-		.name		= SC16IS7XX_NAME,
-		.of_match_table	= sc16is7xx_dt_ids,
-	},
-	.probe		= sc16is7xx_spi_probe,
-	.remove		= sc16is7xx_spi_remove,
-	.id_table	= sc16is7xx_spi_id_table,
-};
-#endif
-
-#ifdef CONFIG_SERIAL_SC16IS7XX_I2C
-static int sc16is7xx_i2c_probe(struct i2c_client *i2c)
-{
-	const struct sc16is7xx_devtype *devtype;
-	struct regmap *regmaps[SC16IS7XX_MAX_PORTS];
-	unsigned int i;
-
-	devtype = i2c_get_match_data(i2c);
-	if (!devtype)
-		return dev_err_probe(&i2c->dev, -ENODEV, "Failed to match device\n");
-
-	for (i = 0; i < devtype->nr_uart; i++) {
-		regcfg.name = sc16is7xx_regmap_name(i);
-		regcfg.read_flag_mask = sc16is7xx_regmap_port_mask(i);
-		regcfg.write_flag_mask = sc16is7xx_regmap_port_mask(i);
-		regmaps[i] = devm_regmap_init_i2c(i2c, &regcfg);
-	}
-
-	return sc16is7xx_probe(&i2c->dev, devtype, regmaps, i2c->irq);
-}
-
-static void sc16is7xx_i2c_remove(struct i2c_client *client)
-{
-	sc16is7xx_remove(&client->dev);
-}
-
-static const struct i2c_device_id sc16is7xx_i2c_id_table[] = {
-	{ "sc16is74x",	(kernel_ulong_t)&sc16is74x_devtype, },
-	{ "sc16is740",	(kernel_ulong_t)&sc16is74x_devtype, },
-	{ "sc16is741",	(kernel_ulong_t)&sc16is74x_devtype, },
-	{ "sc16is750",	(kernel_ulong_t)&sc16is750_devtype, },
-	{ "sc16is752",	(kernel_ulong_t)&sc16is752_devtype, },
-	{ "sc16is760",	(kernel_ulong_t)&sc16is760_devtype, },
-	{ "sc16is762",	(kernel_ulong_t)&sc16is762_devtype, },
-	{ }
-};
-MODULE_DEVICE_TABLE(i2c, sc16is7xx_i2c_id_table);
-
-static struct i2c_driver sc16is7xx_i2c_uart_driver = {
-	.driver = {
-		.name		= SC16IS7XX_NAME,
-		.of_match_table	= sc16is7xx_dt_ids,
-	},
-	.probe		= sc16is7xx_i2c_probe,
-	.remove		= sc16is7xx_i2c_remove,
-	.id_table	= sc16is7xx_i2c_id_table,
-};
-
-#endif
+EXPORT_SYMBOL_GPL(sc16is7xx_regmap_port_mask);
 
 static int __init sc16is7xx_init(void)
 {
-	int ret;
-
-	ret = uart_register_driver(&sc16is7xx_uart);
-	if (ret) {
-		pr_err("Registering UART driver failed\n");
-		return ret;
-	}
-
-#ifdef CONFIG_SERIAL_SC16IS7XX_I2C
-	ret = i2c_add_driver(&sc16is7xx_i2c_uart_driver);
-	if (ret < 0) {
-		pr_err("failed to init sc16is7xx i2c --> %d\n", ret);
-		goto err_i2c;
-	}
-#endif
-
-#ifdef CONFIG_SERIAL_SC16IS7XX_SPI
-	ret = spi_register_driver(&sc16is7xx_spi_uart_driver);
-	if (ret < 0) {
-		pr_err("failed to init sc16is7xx spi --> %d\n", ret);
-		goto err_spi;
-	}
-#endif
-	return ret;
-
-#ifdef CONFIG_SERIAL_SC16IS7XX_SPI
-err_spi:
-#endif
-#ifdef CONFIG_SERIAL_SC16IS7XX_I2C
-	i2c_del_driver(&sc16is7xx_i2c_uart_driver);
-err_i2c:
-#endif
-	uart_unregister_driver(&sc16is7xx_uart);
-	return ret;
+	return uart_register_driver(&sc16is7xx_uart);
 }
 module_init(sc16is7xx_init);
 
 static void __exit sc16is7xx_exit(void)
 {
-#ifdef CONFIG_SERIAL_SC16IS7XX_I2C
-	i2c_del_driver(&sc16is7xx_i2c_uart_driver);
-#endif
-
-#ifdef CONFIG_SERIAL_SC16IS7XX_SPI
-	spi_unregister_driver(&sc16is7xx_spi_uart_driver);
-#endif
 	uart_unregister_driver(&sc16is7xx_uart);
 }
 module_exit(sc16is7xx_exit);
 
 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Jon Ringle <jringle@gridpoint.com>");
-MODULE_DESCRIPTION("SC16IS7XX serial driver");
+MODULE_DESCRIPTION("SC16IS7xx tty serial core driver");
diff --git a/drivers/tty/serial/sc16is7xx.h b/drivers/tty/serial/sc16is7xx.h
new file mode 100644
index 0000000000..afb784eaee
--- /dev/null
+++ b/drivers/tty/serial/sc16is7xx.h
@@ -0,0 +1,41 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/* SC16IS7xx SPI/I2C tty serial driver */
+
+#ifndef _SC16IS7XX_H_
+#define _SC16IS7XX_H_
+
+#include <linux/mod_devicetable.h>
+#include <linux/regmap.h>
+#include <linux/types.h>
+
+#define SC16IS7XX_NAME		"sc16is7xx"
+#define SC16IS7XX_MAX_PORTS	2 /* Maximum number of UART ports per IC. */
+
+struct device;
+
+struct sc16is7xx_devtype {
+	char	name[10];
+	int	nr_gpio;
+	int	nr_uart;
+};
+
+extern const struct regmap_config sc16is7xx_regcfg;
+
+extern const struct of_device_id sc16is7xx_dt_ids[];
+
+extern const struct sc16is7xx_devtype sc16is74x_devtype;
+extern const struct sc16is7xx_devtype sc16is750_devtype;
+extern const struct sc16is7xx_devtype sc16is752_devtype;
+extern const struct sc16is7xx_devtype sc16is760_devtype;
+extern const struct sc16is7xx_devtype sc16is762_devtype;
+
+const char *sc16is7xx_regmap_name(u8 port_id);
+
+unsigned int sc16is7xx_regmap_port_mask(unsigned int port_id);
+
+int sc16is7xx_probe(struct device *dev, const struct sc16is7xx_devtype *devtype,
+		    struct regmap *regmaps[], int irq);
+
+void sc16is7xx_remove(struct device *dev);
+
+#endif /* _SC16IS7XX_H_ */
diff --git a/drivers/tty/serial/sc16is7xx_i2c.c b/drivers/tty/serial/sc16is7xx_i2c.c
new file mode 100644
index 0000000000..3ed47c306d
--- /dev/null
+++ b/drivers/tty/serial/sc16is7xx_i2c.c
@@ -0,0 +1,67 @@
+// SPDX-License-Identifier: GPL-2.0+
+/* SC16IS7xx I2C interface driver */
+
+#include <linux/dev_printk.h>
+#include <linux/i2c.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/regmap.h>
+#include <linux/string.h>
+
+#include "sc16is7xx.h"
+
+static int sc16is7xx_i2c_probe(struct i2c_client *i2c)
+{
+	const struct sc16is7xx_devtype *devtype;
+	struct regmap *regmaps[SC16IS7XX_MAX_PORTS];
+	struct regmap_config regcfg;
+	unsigned int i;
+
+	devtype = i2c_get_match_data(i2c);
+	if (!devtype)
+		return dev_err_probe(&i2c->dev, -ENODEV, "Failed to match device\n");
+
+	memcpy(&regcfg, &sc16is7xx_regcfg, sizeof(struct regmap_config));
+
+	for (i = 0; i < devtype->nr_uart; i++) {
+		regcfg.name = sc16is7xx_regmap_name(i);
+		regcfg.read_flag_mask = sc16is7xx_regmap_port_mask(i);
+		regcfg.write_flag_mask = sc16is7xx_regmap_port_mask(i);
+		regmaps[i] = devm_regmap_init_i2c(i2c, &regcfg);
+	}
+
+	return sc16is7xx_probe(&i2c->dev, devtype, regmaps, i2c->irq);
+}
+
+static void sc16is7xx_i2c_remove(struct i2c_client *client)
+{
+	sc16is7xx_remove(&client->dev);
+}
+
+static const struct i2c_device_id sc16is7xx_i2c_id_table[] = {
+	{ "sc16is74x",	(kernel_ulong_t)&sc16is74x_devtype, },
+	{ "sc16is740",	(kernel_ulong_t)&sc16is74x_devtype, },
+	{ "sc16is741",	(kernel_ulong_t)&sc16is74x_devtype, },
+	{ "sc16is750",	(kernel_ulong_t)&sc16is750_devtype, },
+	{ "sc16is752",	(kernel_ulong_t)&sc16is752_devtype, },
+	{ "sc16is760",	(kernel_ulong_t)&sc16is760_devtype, },
+	{ "sc16is762",	(kernel_ulong_t)&sc16is762_devtype, },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, sc16is7xx_i2c_id_table);
+
+static struct i2c_driver sc16is7xx_i2c_driver = {
+	.driver = {
+		.name		= SC16IS7XX_NAME,
+		.of_match_table	= sc16is7xx_dt_ids,
+	},
+	.probe		= sc16is7xx_i2c_probe,
+	.remove		= sc16is7xx_i2c_remove,
+	.id_table	= sc16is7xx_i2c_id_table,
+};
+
+module_i2c_driver(sc16is7xx_i2c_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("SC16IS7xx I2C interface driver");
+MODULE_IMPORT_NS(SERIAL_NXP_SC16IS7XX);
diff --git a/drivers/tty/serial/sc16is7xx_spi.c b/drivers/tty/serial/sc16is7xx_spi.c
new file mode 100644
index 0000000000..73df36f8a7
--- /dev/null
+++ b/drivers/tty/serial/sc16is7xx_spi.c
@@ -0,0 +1,90 @@
+// SPDX-License-Identifier: GPL-2.0+
+/* SC16IS7xx SPI interface driver */
+
+#include <linux/dev_printk.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/regmap.h>
+#include <linux/spi/spi.h>
+#include <linux/string.h>
+#include <linux/units.h>
+
+#include "sc16is7xx.h"
+
+/* SPI definitions */
+#define SC16IS7XX_SPI_READ_BIT	BIT(7)
+
+static int sc16is7xx_spi_probe(struct spi_device *spi)
+{
+	const struct sc16is7xx_devtype *devtype;
+	struct regmap *regmaps[SC16IS7XX_MAX_PORTS];
+	struct regmap_config regcfg;
+	unsigned int i;
+	int ret;
+
+	/* Setup SPI bus */
+	spi->bits_per_word	= 8;
+	/* For all variants, only mode 0 is supported */
+	if ((spi->mode & SPI_MODE_X_MASK) != SPI_MODE_0)
+		return dev_err_probe(&spi->dev, -EINVAL, "Unsupported SPI mode\n");
+
+	spi->mode		= spi->mode ? : SPI_MODE_0;
+	spi->max_speed_hz	= spi->max_speed_hz ? : 4 * HZ_PER_MHZ;
+	ret = spi_setup(spi);
+	if (ret)
+		return ret;
+
+	devtype = spi_get_device_match_data(spi);
+	if (!devtype)
+		return dev_err_probe(&spi->dev, -ENODEV, "Failed to match device\n");
+
+	memcpy(&regcfg, &sc16is7xx_regcfg, sizeof(struct regmap_config));
+
+	for (i = 0; i < devtype->nr_uart; i++) {
+		regcfg.name = sc16is7xx_regmap_name(i);
+		/*
+		 * If read_flag_mask is 0, the regmap code sets it to a default
+		 * of 0x80. Since we specify our own mask, we must add the READ
+		 * bit ourselves:
+		 */
+		regcfg.read_flag_mask = sc16is7xx_regmap_port_mask(i) |
+			SC16IS7XX_SPI_READ_BIT;
+		regcfg.write_flag_mask = sc16is7xx_regmap_port_mask(i);
+		regmaps[i] = devm_regmap_init_spi(spi, &regcfg);
+	}
+
+	return sc16is7xx_probe(&spi->dev, devtype, regmaps, spi->irq);
+}
+
+static void sc16is7xx_spi_remove(struct spi_device *spi)
+{
+	sc16is7xx_remove(&spi->dev);
+}
+
+static const struct spi_device_id sc16is7xx_spi_id_table[] = {
+	{ "sc16is74x",	(kernel_ulong_t)&sc16is74x_devtype, },
+	{ "sc16is740",	(kernel_ulong_t)&sc16is74x_devtype, },
+	{ "sc16is741",	(kernel_ulong_t)&sc16is74x_devtype, },
+	{ "sc16is750",	(kernel_ulong_t)&sc16is750_devtype, },
+	{ "sc16is752",	(kernel_ulong_t)&sc16is752_devtype, },
+	{ "sc16is760",	(kernel_ulong_t)&sc16is760_devtype, },
+	{ "sc16is762",	(kernel_ulong_t)&sc16is762_devtype, },
+	{ }
+};
+MODULE_DEVICE_TABLE(spi, sc16is7xx_spi_id_table);
+
+static struct spi_driver sc16is7xx_spi_driver = {
+	.driver = {
+		.name		= SC16IS7XX_NAME,
+		.of_match_table	= sc16is7xx_dt_ids,
+	},
+	.probe		= sc16is7xx_spi_probe,
+	.remove		= sc16is7xx_spi_remove,
+	.id_table	= sc16is7xx_spi_id_table,
+};
+
+module_spi_driver(sc16is7xx_spi_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("SC16IS7xx SPI interface driver");
+MODULE_IMPORT_NS(SERIAL_NXP_SC16IS7XX);
diff --git a/drivers/tty/serial/sccnxp.c b/drivers/tty/serial/sccnxp.c
index f24217a560..6d1d142fd2 100644
--- a/drivers/tty/serial/sccnxp.c
+++ b/drivers/tty/serial/sccnxp.c
@@ -439,7 +439,7 @@ static void sccnxp_handle_rx(struct uart_port *port)
 static void sccnxp_handle_tx(struct uart_port *port)
 {
 	u8 sr;
-	struct circ_buf *xmit = &port->state->xmit;
+	struct tty_port *tport = &port->state->port;
 	struct sccnxp_port *s = dev_get_drvdata(port->dev);
 
 	if (unlikely(port->x_char)) {
@@ -449,7 +449,7 @@ static void sccnxp_handle_tx(struct uart_port *port)
 		return;
 	}
 
-	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
+	if (kfifo_is_empty(&tport->xmit_fifo) || uart_tx_stopped(port)) {
 		/* Disable TX if FIFO is empty */
 		if (sccnxp_port_read(port, SCCNXP_SR_REG) & SR_TXEMT) {
 			sccnxp_disable_irq(port, IMR_TXRDY);
@@ -461,16 +461,20 @@ static void sccnxp_handle_tx(struct uart_port *port)
 		return;
 	}
 
-	while (!uart_circ_empty(xmit)) {
+	while (1) {
+		unsigned char ch;
+
 		sr = sccnxp_port_read(port, SCCNXP_SR_REG);
 		if (!(sr & SR_TXRDY))
 			break;
 
-		sccnxp_port_write(port, SCCNXP_THR_REG, xmit->buf[xmit->tail]);
-		uart_xmit_advance(port, 1);
+		if (!uart_fifo_get(port, &ch))
+			break;
+
+		sccnxp_port_write(port, SCCNXP_THR_REG, ch);
 	}
 
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+	if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)
 		uart_write_wakeup(port);
 }
 
diff --git a/drivers/tty/serial/serial-tegra.c b/drivers/tty/serial/serial-tegra.c
index 525f3a2f7b..1183ca54ab 100644
--- a/drivers/tty/serial/serial-tegra.c
+++ b/drivers/tty/serial/serial-tegra.c
@@ -484,18 +484,18 @@ static void tegra_uart_release_port(struct uart_port *u)
 
 static void tegra_uart_fill_tx_fifo(struct tegra_uart_port *tup, int max_bytes)
 {
-	struct circ_buf *xmit = &tup->uport.state->xmit;
+	unsigned char ch;
 	int i;
 
 	for (i = 0; i < max_bytes; i++) {
-		BUG_ON(uart_circ_empty(xmit));
 		if (tup->cdata->tx_fifo_full_status) {
 			unsigned long lsr = tegra_uart_read(tup, UART_LSR);
 			if ((lsr & TEGRA_UART_LSR_TXFIFO_FULL))
 				break;
 		}
-		tegra_uart_write(tup, xmit->buf[xmit->tail], UART_TX);
-		uart_xmit_advance(&tup->uport, 1);
+		if (WARN_ON_ONCE(!uart_fifo_get(&tup->uport, &ch)))
+			break;
+		tegra_uart_write(tup, ch, UART_TX);
 	}
 }
 
@@ -514,7 +514,7 @@ static void tegra_uart_start_pio_tx(struct tegra_uart_port *tup,
 static void tegra_uart_tx_dma_complete(void *args)
 {
 	struct tegra_uart_port *tup = args;
-	struct circ_buf *xmit = &tup->uport.state->xmit;
+	struct tty_port *tport = &tup->uport.state->port;
 	struct dma_tx_state state;
 	unsigned long flags;
 	unsigned int count;
@@ -525,7 +525,7 @@ static void tegra_uart_tx_dma_complete(void *args)
 	uart_port_lock_irqsave(&tup->uport, &flags);
 	uart_xmit_advance(&tup->uport, count);
 	tup->tx_in_progress = 0;
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+	if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)
 		uart_write_wakeup(&tup->uport);
 	tegra_uart_start_next_tx(tup);
 	uart_port_unlock_irqrestore(&tup->uport, flags);
@@ -534,11 +534,14 @@ static void tegra_uart_tx_dma_complete(void *args)
 static int tegra_uart_start_tx_dma(struct tegra_uart_port *tup,
 		unsigned long count)
 {
-	struct circ_buf *xmit = &tup->uport.state->xmit;
+	struct tty_port *tport = &tup->uport.state->port;
 	dma_addr_t tx_phys_addr;
+	unsigned int tail;
 
 	tup->tx_bytes = count & ~(0xF);
-	tx_phys_addr = tup->tx_dma_buf_phys + xmit->tail;
+	WARN_ON_ONCE(kfifo_out_linear(&tport->xmit_fifo, &tail,
+			UART_XMIT_SIZE) < count);
+	tx_phys_addr = tup->tx_dma_buf_phys + tail;
 
 	dma_sync_single_for_device(tup->uport.dev, tx_phys_addr,
 				   tup->tx_bytes, DMA_TO_DEVICE);
@@ -562,18 +565,21 @@ static int tegra_uart_start_tx_dma(struct tegra_uart_port *tup,
 
 static void tegra_uart_start_next_tx(struct tegra_uart_port *tup)
 {
+	struct tty_port *tport = &tup->uport.state->port;
+	unsigned char *tail_ptr;
 	unsigned long tail;
-	unsigned long count;
-	struct circ_buf *xmit = &tup->uport.state->xmit;
+	unsigned int count;
 
 	if (!tup->current_baud)
 		return;
 
-	tail = (unsigned long)&xmit->buf[xmit->tail];
-	count = CIRC_CNT_TO_END(xmit->head, xmit->tail, UART_XMIT_SIZE);
+	count = kfifo_out_linear_ptr(&tport->xmit_fifo, &tail_ptr,
+			UART_XMIT_SIZE);
 	if (!count)
 		return;
 
+	tail = (unsigned long)tail_ptr;
+
 	if (tup->use_tx_pio || count < TEGRA_UART_MIN_DMA)
 		tegra_uart_start_pio_tx(tup, count);
 	else if (BYTES_TO_ALIGN(tail) > 0)
@@ -586,9 +592,9 @@ static void tegra_uart_start_next_tx(struct tegra_uart_port *tup)
 static void tegra_uart_start_tx(struct uart_port *u)
 {
 	struct tegra_uart_port *tup = to_tegra_uport(u);
-	struct circ_buf *xmit = &u->state->xmit;
+	struct tty_port *tport = &u->state->port;
 
-	if (!uart_circ_empty(xmit) && !tup->tx_in_progress)
+	if (!kfifo_is_empty(&tport->xmit_fifo) && !tup->tx_in_progress)
 		tegra_uart_start_next_tx(tup);
 }
 
@@ -628,11 +634,11 @@ static void tegra_uart_stop_tx(struct uart_port *u)
 
 static void tegra_uart_handle_tx_pio(struct tegra_uart_port *tup)
 {
-	struct circ_buf *xmit = &tup->uport.state->xmit;
+	struct tty_port *tport = &tup->uport.state->port;
 
 	tegra_uart_fill_tx_fifo(tup, tup->tx_bytes);
 	tup->tx_in_progress = 0;
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+	if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)
 		uart_write_wakeup(&tup->uport);
 	tegra_uart_start_next_tx(tup);
 }
@@ -1169,15 +1175,14 @@ static int tegra_uart_dma_channel_allocate(struct tegra_uart_port *tup,
 		tup->rx_dma_buf_virt = dma_buf;
 		tup->rx_dma_buf_phys = dma_phys;
 	} else {
+		dma_buf = tup->uport.state->port.xmit_buf;
 		dma_phys = dma_map_single(tup->uport.dev,
-			tup->uport.state->xmit.buf, UART_XMIT_SIZE,
-			DMA_TO_DEVICE);
+			dma_buf, UART_XMIT_SIZE, DMA_TO_DEVICE);
 		if (dma_mapping_error(tup->uport.dev, dma_phys)) {
 			dev_err(tup->uport.dev, "dma_map_single tx failed\n");
 			dma_release_channel(dma_chan);
 			return -ENOMEM;
 		}
-		dma_buf = tup->uport.state->xmit.buf;
 		dma_sconfig.dst_addr = tup->uport.mapbase;
 		dma_sconfig.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
 		dma_sconfig.dst_maxburst = 16;
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index c476d88435..2a8006e3d6 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -243,25 +243,12 @@ static void uart_change_line_settings(struct tty_struct *tty, struct uart_state
 	uart_port_unlock_irq(uport);
 }
 
-/*
- * Startup the port.  This will be called once per open.  All calls
- * will be serialised by the per-port mutex.
- */
-static int uart_port_startup(struct tty_struct *tty, struct uart_state *state,
-			     bool init_hw)
+static int uart_alloc_xmit_buf(struct tty_port *port)
 {
-	struct uart_port *uport = uart_port_check(state);
+	struct uart_state *state = container_of(port, struct uart_state, port);
+	struct uart_port *uport;
 	unsigned long flags;
 	unsigned long page;
-	int retval = 0;
-
-	if (uport->type == PORT_UNKNOWN)
-		return 1;
-
-	/*
-	 * Make sure the device is in D0 state.
-	 */
-	uart_change_pm(state, UART_PM_STATE_ON);
 
 	/*
 	 * Initialise and allocate the transmit and temporary
@@ -271,20 +258,68 @@ static int uart_port_startup(struct tty_struct *tty, struct uart_state *state,
 	if (!page)
 		return -ENOMEM;
 
-	uart_port_lock(state, flags);
-	if (!state->xmit.buf) {
-		state->xmit.buf = (unsigned char *) page;
-		uart_circ_clear(&state->xmit);
+	uport = uart_port_lock(state, flags);
+	if (!state->port.xmit_buf) {
+		state->port.xmit_buf = (unsigned char *)page;
+		kfifo_init(&state->port.xmit_fifo, state->port.xmit_buf,
+				PAGE_SIZE);
 		uart_port_unlock(uport, flags);
 	} else {
 		uart_port_unlock(uport, flags);
 		/*
 		 * Do not free() the page under the port lock, see
-		 * uart_shutdown().
+		 * uart_free_xmit_buf().
 		 */
 		free_page(page);
 	}
 
+	return 0;
+}
+
+static void uart_free_xmit_buf(struct tty_port *port)
+{
+	struct uart_state *state = container_of(port, struct uart_state, port);
+	struct uart_port *uport;
+	unsigned long flags;
+	char *xmit_buf;
+
+	/*
+	 * Do not free() the transmit buffer page under the port lock since
+	 * this can create various circular locking scenarios. For instance,
+	 * console driver may need to allocate/free a debug object, which
+	 * can end up in printk() recursion.
+	 */
+	uport = uart_port_lock(state, flags);
+	xmit_buf = port->xmit_buf;
+	port->xmit_buf = NULL;
+	INIT_KFIFO(port->xmit_fifo);
+	uart_port_unlock(uport, flags);
+
+	free_page((unsigned long)xmit_buf);
+}
+
+/*
+ * Startup the port.  This will be called once per open.  All calls
+ * will be serialised by the per-port mutex.
+ */
+static int uart_port_startup(struct tty_struct *tty, struct uart_state *state,
+			     bool init_hw)
+{
+	struct uart_port *uport = uart_port_check(state);
+	int retval;
+
+	if (uport->type == PORT_UNKNOWN)
+		return 1;
+
+	/*
+	 * Make sure the device is in D0 state.
+	 */
+	uart_change_pm(state, UART_PM_STATE_ON);
+
+	retval = uart_alloc_xmit_buf(&state->port);
+	if (retval)
+		return retval;
+
 	retval = uport->ops->startup(uport);
 	if (retval == 0) {
 		if (uart_console(uport) && uport->cons->cflag) {
@@ -356,8 +391,6 @@ static void uart_shutdown(struct tty_struct *tty, struct uart_state *state)
 {
 	struct uart_port *uport = uart_port_check(state);
 	struct tty_port *port = &state->port;
-	unsigned long flags;
-	char *xmit_buf = NULL;
 
 	/*
 	 * Set the TTY IO error marker
@@ -393,18 +426,7 @@ static void uart_shutdown(struct tty_struct *tty, struct uart_state *state)
 	 */
 	tty_port_set_suspended(port, false);
 
-	/*
-	 * Do not free() the transmit buffer page under the port lock since
-	 * this can create various circular locking scenarios. For instance,
-	 * console driver may need to allocate/free a debug object, which
-	 * can endup in printk() recursion.
-	 */
-	uart_port_lock(state, flags);
-	xmit_buf = state->xmit.buf;
-	state->xmit.buf = NULL;
-	uart_port_unlock(uport, flags);
-
-	free_page((unsigned long)xmit_buf);
+	uart_free_xmit_buf(port);
 }
 
 /**
@@ -565,22 +587,17 @@ static int uart_put_char(struct tty_struct *tty, u8 c)
 {
 	struct uart_state *state = tty->driver_data;
 	struct uart_port *port;
-	struct circ_buf *circ;
 	unsigned long flags;
 	int ret = 0;
 
-	circ = &state->xmit;
 	port = uart_port_lock(state, flags);
-	if (!circ->buf) {
+	if (!state->port.xmit_buf) {
 		uart_port_unlock(port, flags);
 		return 0;
 	}
 
-	if (port && uart_circ_chars_free(circ) != 0) {
-		circ->buf[circ->head] = c;
-		circ->head = (circ->head + 1) & (UART_XMIT_SIZE - 1);
-		ret = 1;
-	}
+	if (port)
+		ret = kfifo_put(&state->port.xmit_fifo, c);
 	uart_port_unlock(port, flags);
 	return ret;
 }
@@ -594,9 +611,8 @@ static ssize_t uart_write(struct tty_struct *tty, const u8 *buf, size_t count)
 {
 	struct uart_state *state = tty->driver_data;
 	struct uart_port *port;
-	struct circ_buf *circ;
 	unsigned long flags;
-	int c, ret = 0;
+	int ret = 0;
 
 	/*
 	 * This means you called this function _after_ the port was
@@ -606,24 +622,13 @@ static ssize_t uart_write(struct tty_struct *tty, const u8 *buf, size_t count)
 		return -EL3HLT;
 
 	port = uart_port_lock(state, flags);
-	circ = &state->xmit;
-	if (!circ->buf) {
+	if (!state->port.xmit_buf) {
 		uart_port_unlock(port, flags);
 		return 0;
 	}
 
-	while (port) {
-		c = CIRC_SPACE_TO_END(circ->head, circ->tail, UART_XMIT_SIZE);
-		if (count < c)
-			c = count;
-		if (c <= 0)
-			break;
-		memcpy(circ->buf + circ->head, buf, c);
-		circ->head = (circ->head + c) & (UART_XMIT_SIZE - 1);
-		buf += c;
-		count -= c;
-		ret += c;
-	}
+	if (port)
+		ret = kfifo_in(&state->port.xmit_fifo, buf, count);
 
 	__uart_start(state);
 	uart_port_unlock(port, flags);
@@ -638,7 +643,7 @@ static unsigned int uart_write_room(struct tty_struct *tty)
 	unsigned int ret;
 
 	port = uart_port_lock(state, flags);
-	ret = uart_circ_chars_free(&state->xmit);
+	ret = kfifo_avail(&state->port.xmit_fifo);
 	uart_port_unlock(port, flags);
 	return ret;
 }
@@ -651,7 +656,7 @@ static unsigned int uart_chars_in_buffer(struct tty_struct *tty)
 	unsigned int ret;
 
 	port = uart_port_lock(state, flags);
-	ret = uart_circ_chars_pending(&state->xmit);
+	ret = kfifo_len(&state->port.xmit_fifo);
 	uart_port_unlock(port, flags);
 	return ret;
 }
@@ -674,7 +679,7 @@ static void uart_flush_buffer(struct tty_struct *tty)
 	port = uart_port_lock(state, flags);
 	if (!port)
 		return;
-	uart_circ_clear(&state->xmit);
+	kfifo_reset(&state->port.xmit_fifo);
 	if (port->ops->flush_buffer)
 		port->ops->flush_buffer(port);
 	uart_port_unlock(port, flags);
@@ -1077,7 +1082,7 @@ static int uart_get_lsr_info(struct tty_struct *tty,
 	 * interrupt happens).
 	 */
 	if (uport->x_char ||
-	    ((uart_circ_chars_pending(&state->xmit) > 0) &&
+	    (!kfifo_is_empty(&state->port.xmit_fifo) &&
 	     !uart_tx_stopped(uport)))
 		result &= ~TIOCSER_TEMT;
 
@@ -1775,7 +1780,6 @@ static void uart_tty_port_shutdown(struct tty_port *port)
 {
 	struct uart_state *state = container_of(port, struct uart_state, port);
 	struct uart_port *uport = uart_port_check(state);
-	char *buf;
 
 	/*
 	 * At this point, we stop accepting input.  To do this, we
@@ -1798,16 +1802,7 @@ static void uart_tty_port_shutdown(struct tty_port *port)
 	 */
 	tty_port_set_suspended(port, false);
 
-	/*
-	 * Free the transmit buffer.
-	 */
-	uart_port_lock_irq(uport);
-	uart_circ_clear(&state->xmit);
-	buf = state->xmit.buf;
-	state->xmit.buf = NULL;
-	uart_port_unlock_irq(uport);
-
-	free_page((unsigned long)buf);
+	uart_free_xmit_buf(port);
 
 	uart_change_pm(state, UART_PM_STATE_OFF);
 }
@@ -2413,6 +2408,7 @@ int uart_suspend_port(struct uart_driver *drv, struct uart_port *uport)
 			uport->ops->stop_rx(uport);
 			uart_port_unlock_irq(uport);
 		}
+		device_set_awake_path(uport->dev);
 		goto unlock;
 	}
 
@@ -3211,6 +3207,9 @@ static int serial_core_add_one_port(struct uart_driver *drv, struct uart_port *u
 	if (uport->attr_group)
 		uport->tty_groups[1] = uport->attr_group;
 
+	/* Ensure serdev drivers can call serdev_device_open() right away */
+	uport->flags &= ~UPF_DEAD;
+
 	/*
 	 * Register the port whether it's detected or not.  This allows
 	 * setserial to be used to alter this port's parameters.
@@ -3221,6 +3220,7 @@ static int serial_core_add_one_port(struct uart_driver *drv, struct uart_port *u
 	if (!IS_ERR(tty_dev)) {
 		device_set_wakeup_capable(tty_dev, 1);
 	} else {
+		uport->flags |= UPF_DEAD;
 		dev_err(uport->dev, "Cannot register tty device on line %d\n",
 		       uport->line);
 	}
@@ -3426,8 +3426,6 @@ int serial_core_register_port(struct uart_driver *drv, struct uart_port *port)
 	if (ret)
 		goto err_unregister_port_dev;
 
-	port->flags &= ~UPF_DEAD;
-
 	mutex_unlock(&port_mutex);
 
 	return 0;
diff --git a/drivers/tty/serial/serial_port.c b/drivers/tty/serial/serial_port.c
index 66fd117d8a..d35f1d2415 100644
--- a/drivers/tty/serial/serial_port.c
+++ b/drivers/tty/serial/serial_port.c
@@ -11,6 +11,7 @@
 #include <linux/of.h>
 #include <linux/platform_device.h>
 #include <linux/pm_runtime.h>
+#include <linux/pnp.h>
 #include <linux/property.h>
 #include <linux/serial_core.h>
 #include <linux/spinlock.h>
@@ -23,7 +24,7 @@
 static int __serial_port_busy(struct uart_port *port)
 {
 	return !uart_tx_stopped(port) &&
-		uart_circ_chars_pending(&port->state->xmit);
+		!kfifo_is_empty(&port->state->port.xmit_fifo);
 }
 
 static int serial_port_runtime_resume(struct device *dev)
@@ -262,7 +263,11 @@ static int __uart_read_properties(struct uart_port *port, bool use_defaults)
 
 	if (dev_is_platform(dev))
 		ret = platform_get_irq(to_platform_device(dev), 0);
-	else
+	else if (dev_is_pnp(dev)) {
+		ret = pnp_irq(to_pnp_dev(dev), 0);
+		if (ret < 0)
+			ret = -ENXIO;
+	} else
 		ret = fwnode_irq_get(dev_fwnode(dev), 0);
 	if (ret == -EPROBE_DEFER)
 		return ret;
diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c
index a6f3517dce..f738980a8b 100644
--- a/drivers/tty/serial/sh-sci.c
+++ b/drivers/tty/serial/sh-sci.c
@@ -585,7 +585,7 @@ static void sci_start_tx(struct uart_port *port)
 			sci_serial_out(port, SCSCR, new);
 	}
 
-	if (s->chan_tx && !uart_circ_empty(&s->port.state->xmit) &&
+	if (s->chan_tx && !kfifo_is_empty(&port->state->port.xmit_fifo) &&
 	    dma_submit_error(s->cookie_tx)) {
 		if (s->cfg->regtype == SCIx_RZ_SCIFA_REGTYPE)
 			/* Switch irq from SCIF to DMA */
@@ -817,7 +817,7 @@ static int sci_rxfill(struct uart_port *port)
 
 static void sci_transmit_chars(struct uart_port *port)
 {
-	struct circ_buf *xmit = &port->state->xmit;
+	struct tty_port *tport = &port->state->port;
 	unsigned int stopped = uart_tx_stopped(port);
 	unsigned short status;
 	unsigned short ctrl;
@@ -826,7 +826,7 @@ static void sci_transmit_chars(struct uart_port *port)
 	status = sci_serial_in(port, SCxSR);
 	if (!(status & SCxSR_TDxE(port))) {
 		ctrl = sci_serial_in(port, SCSCR);
-		if (uart_circ_empty(xmit))
+		if (kfifo_is_empty(&tport->xmit_fifo))
 			ctrl &= ~SCSCR_TIE;
 		else
 			ctrl |= SCSCR_TIE;
@@ -842,15 +842,14 @@ static void sci_transmit_chars(struct uart_port *port)
 		if (port->x_char) {
 			c = port->x_char;
 			port->x_char = 0;
-		} else if (!uart_circ_empty(xmit) && !stopped) {
-			c = xmit->buf[xmit->tail];
-			xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
-		} else if (port->type == PORT_SCI && uart_circ_empty(xmit)) {
-			ctrl = sci_serial_in(port, SCSCR);
-			ctrl &= ~SCSCR_TE;
-			sci_serial_out(port, SCSCR, ctrl);
-			return;
-		} else {
+		} else if (stopped || !kfifo_get(&tport->xmit_fifo, &c)) {
+			if (port->type == PORT_SCI &&
+				   kfifo_is_empty(&tport->xmit_fifo)) {
+				ctrl = sci_serial_in(port, SCSCR);
+				ctrl &= ~SCSCR_TE;
+				sci_serial_out(port, SCSCR, ctrl);
+				return;
+			}
 			break;
 		}
 
@@ -861,9 +860,9 @@ static void sci_transmit_chars(struct uart_port *port)
 
 	sci_clear_SCxSR(port, SCxSR_TDxE_CLEAR(port));
 
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+	if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)
 		uart_write_wakeup(port);
-	if (uart_circ_empty(xmit)) {
+	if (kfifo_is_empty(&tport->xmit_fifo)) {
 		if (port->type == PORT_SCI) {
 			ctrl = sci_serial_in(port, SCSCR);
 			ctrl &= ~SCSCR_TIE;
@@ -1199,7 +1198,7 @@ static void sci_dma_tx_complete(void *arg)
 {
 	struct sci_port *s = arg;
 	struct uart_port *port = &s->port;
-	struct circ_buf *xmit = &port->state->xmit;
+	struct tty_port *tport = &port->state->port;
 	unsigned long flags;
 
 	dev_dbg(port->dev, "%s(%d)\n", __func__, port->line);
@@ -1208,10 +1207,10 @@ static void sci_dma_tx_complete(void *arg)
 
 	uart_xmit_advance(port, s->tx_dma_len);
 
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+	if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)
 		uart_write_wakeup(port);
 
-	if (!uart_circ_empty(xmit)) {
+	if (!kfifo_is_empty(&tport->xmit_fifo)) {
 		s->cookie_tx = 0;
 		schedule_work(&s->work_tx);
 	} else {
@@ -1258,6 +1257,7 @@ static int sci_dma_rx_find_active(struct sci_port *s)
 	return -1;
 }
 
+/* Must only be called with uart_port_lock taken */
 static void sci_dma_rx_chan_invalidate(struct sci_port *s)
 {
 	unsigned int i;
@@ -1324,14 +1324,14 @@ static void sci_dma_rx_complete(void *arg)
 	dev_dbg(port->dev, "%s(%d) active cookie %d\n", __func__, port->line,
 		s->active_rx);
 
+	hrtimer_cancel(&s->rx_timer);
+
 	uart_port_lock_irqsave(port, &flags);
 
 	active = sci_dma_rx_find_active(s);
 	if (active >= 0)
 		count = sci_dma_rx_push(s, s->rx_buf[active], s->buf_len_rx);
 
-	start_hrtimer_us(&s->rx_timer, s->rx_timeout);
-
 	if (count)
 		tty_flip_buffer_push(&port->state->port);
 
@@ -1354,17 +1354,18 @@ static void sci_dma_rx_complete(void *arg)
 	uart_port_unlock_irqrestore(port, flags);
 	dev_dbg(port->dev, "%s: cookie %d #%d, new active cookie %d\n",
 		__func__, s->cookie_rx[active], active, s->active_rx);
+
+	start_hrtimer_us(&s->rx_timer, s->rx_timeout);
+
 	return;
 
 fail:
-	uart_port_unlock_irqrestore(port, flags);
-	dev_warn(port->dev, "Failed submitting Rx DMA descriptor\n");
 	/* Switch to PIO */
-	uart_port_lock_irqsave(port, &flags);
 	dmaengine_terminate_async(chan);
 	sci_dma_rx_chan_invalidate(s);
 	sci_dma_rx_reenable_irq(s);
 	uart_port_unlock_irqrestore(port, flags);
+	dev_warn(port->dev, "Failed submitting Rx DMA descriptor\n");
 }
 
 static void sci_dma_tx_release(struct sci_port *s)
@@ -1429,10 +1430,10 @@ static void sci_dma_tx_work_fn(struct work_struct *work)
 	struct dma_async_tx_descriptor *desc;
 	struct dma_chan *chan = s->chan_tx;
 	struct uart_port *port = &s->port;
-	struct circ_buf *xmit = &port->state->xmit;
+	struct tty_port *tport = &port->state->port;
 	unsigned long flags;
+	unsigned int tail;
 	dma_addr_t buf;
-	int head, tail;
 
 	/*
 	 * DMA is idle now.
@@ -1442,10 +1443,9 @@ static void sci_dma_tx_work_fn(struct work_struct *work)
 	 * consistent xmit buffer state.
 	 */
 	uart_port_lock_irq(port);
-	head = xmit->head;
-	tail = xmit->tail;
+	s->tx_dma_len = kfifo_out_linear(&tport->xmit_fifo, &tail,
+			UART_XMIT_SIZE);
 	buf = s->tx_dma_addr + tail;
-	s->tx_dma_len = CIRC_CNT_TO_END(head, tail, UART_XMIT_SIZE);
 	if (!s->tx_dma_len) {
 		/* Transmit buffer has been flushed */
 		uart_port_unlock_irq(port);
@@ -1474,8 +1474,8 @@ static void sci_dma_tx_work_fn(struct work_struct *work)
 	}
 
 	uart_port_unlock_irq(port);
-	dev_dbg(port->dev, "%s: %p: %d...%d, cookie %d\n",
-		__func__, xmit->buf, tail, head, s->cookie_tx);
+	dev_dbg(port->dev, "%s: %p: %u, cookie %d\n",
+		__func__, tport->xmit_buf, tail, s->cookie_tx);
 
 	dma_async_issue_pending(chan);
 	return;
@@ -1590,6 +1590,7 @@ static struct dma_chan *sci_request_dma_chan(struct uart_port *port,
 static void sci_request_dma(struct uart_port *port)
 {
 	struct sci_port *s = to_sci_port(port);
+	struct tty_port *tport = &port->state->port;
 	struct dma_chan *chan;
 
 	dev_dbg(port->dev, "%s: port %d\n", __func__, port->line);
@@ -1618,7 +1619,7 @@ static void sci_request_dma(struct uart_port *port)
 	if (chan) {
 		/* UART circular tx buffer is an aligned page. */
 		s->tx_dma_addr = dma_map_single(chan->device->dev,
-						port->state->xmit.buf,
+						tport->xmit_buf,
 						UART_XMIT_SIZE,
 						DMA_TO_DEVICE);
 		if (dma_mapping_error(chan->device->dev, s->tx_dma_addr)) {
@@ -1627,7 +1628,7 @@ static void sci_request_dma(struct uart_port *port)
 		} else {
 			dev_dbg(port->dev, "%s: mapped %lu@%p to %pad\n",
 				__func__, UART_XMIT_SIZE,
-				port->state->xmit.buf, &s->tx_dma_addr);
+				tport->xmit_buf, &s->tx_dma_addr);
 
 			INIT_WORK(&s->work_tx, sci_dma_tx_work_fn);
 			s->chan_tx_saved = s->chan_tx = chan;
diff --git a/drivers/tty/serial/sifive.c b/drivers/tty/serial/sifive.c
index 0670fd9f84..cbfce65c9d 100644
--- a/drivers/tty/serial/sifive.c
+++ b/drivers/tty/serial/sifive.c
@@ -761,7 +761,7 @@ static int __init early_sifive_serial_setup(struct earlycon_device *dev,
 }
 
 OF_EARLYCON_DECLARE(sifive, "sifive,uart0", early_sifive_serial_setup);
-OF_EARLYCON_DECLARE(sifive, "sifive,fu540-c000-uart0",
+OF_EARLYCON_DECLARE(sifive, "sifive,fu540-c000-uart",
 		    early_sifive_serial_setup);
 #endif /* CONFIG_SERIAL_EARLYCON */
 
@@ -1032,7 +1032,7 @@ static DEFINE_SIMPLE_DEV_PM_OPS(sifive_uart_pm_ops, sifive_serial_suspend,
 				sifive_serial_resume);
 
 static const struct of_device_id sifive_serial_of_match[] = {
-	{ .compatible = "sifive,fu540-c000-uart0" },
+	{ .compatible = "sifive,fu540-c000-uart" },
 	{ .compatible = "sifive,uart0" },
 	{},
 };
diff --git a/drivers/tty/serial/sprd_serial.c b/drivers/tty/serial/sprd_serial.c
index 15f14fa593..3fc54cc02a 100644
--- a/drivers/tty/serial/sprd_serial.c
+++ b/drivers/tty/serial/sprd_serial.c
@@ -227,13 +227,13 @@ static int sprd_tx_buf_remap(struct uart_port *port)
 {
 	struct sprd_uart_port *sp =
 		container_of(port, struct sprd_uart_port, port);
-	struct circ_buf *xmit = &port->state->xmit;
+	struct tty_port *tport = &port->state->port;
+	unsigned char *tail;
 
-	sp->tx_dma.trans_len =
-		CIRC_CNT_TO_END(xmit->head, xmit->tail, UART_XMIT_SIZE);
+	sp->tx_dma.trans_len = kfifo_out_linear_ptr(&tport->xmit_fifo, &tail,
+			UART_XMIT_SIZE);
 
-	sp->tx_dma.phys_addr = dma_map_single(port->dev,
-					      (void *)&(xmit->buf[xmit->tail]),
+	sp->tx_dma.phys_addr = dma_map_single(port->dev, tail,
 					      sp->tx_dma.trans_len,
 					      DMA_TO_DEVICE);
 	return dma_mapping_error(port->dev, sp->tx_dma.phys_addr);
@@ -244,7 +244,7 @@ static void sprd_complete_tx_dma(void *data)
 	struct uart_port *port = (struct uart_port *)data;
 	struct sprd_uart_port *sp =
 		container_of(port, struct sprd_uart_port, port);
-	struct circ_buf *xmit = &port->state->xmit;
+	struct tty_port *tport = &port->state->port;
 	unsigned long flags;
 
 	uart_port_lock_irqsave(port, &flags);
@@ -253,10 +253,10 @@ static void sprd_complete_tx_dma(void *data)
 
 	uart_xmit_advance(port, sp->tx_dma.trans_len);
 
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+	if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)
 		uart_write_wakeup(port);
 
-	if (uart_circ_empty(xmit) || sprd_tx_buf_remap(port) ||
+	if (kfifo_is_empty(&tport->xmit_fifo) || sprd_tx_buf_remap(port) ||
 	    sprd_tx_dma_config(port))
 		sp->tx_dma.trans_len = 0;
 
@@ -319,7 +319,7 @@ static void sprd_start_tx_dma(struct uart_port *port)
 {
 	struct sprd_uart_port *sp =
 		container_of(port, struct sprd_uart_port, port);
-	struct circ_buf *xmit = &port->state->xmit;
+	struct tty_port *tport = &port->state->port;
 
 	if (port->x_char) {
 		serial_out(port, SPRD_TXD, port->x_char);
@@ -328,7 +328,7 @@ static void sprd_start_tx_dma(struct uart_port *port)
 		return;
 	}
 
-	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
+	if (kfifo_is_empty(&tport->xmit_fifo) || uart_tx_stopped(port)) {
 		sprd_stop_tx_dma(port);
 		return;
 	}
diff --git a/drivers/tty/serial/st-asc.c b/drivers/tty/serial/st-asc.c
index a23e595518..f91753a40a 100644
--- a/drivers/tty/serial/st-asc.c
+++ b/drivers/tty/serial/st-asc.c
@@ -387,9 +387,9 @@ static unsigned int asc_get_mctrl(struct uart_port *port)
 /* There are probably characters waiting to be transmitted. */
 static void asc_start_tx(struct uart_port *port)
 {
-	struct circ_buf *xmit = &port->state->xmit;
+	struct tty_port *tport = &port->state->port;
 
-	if (!uart_circ_empty(xmit))
+	if (!kfifo_is_empty(&tport->xmit_fifo))
 		asc_enable_tx_interrupts(port);
 }
 
diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c
index 4fa5a03eba..e1e7bc04c5 100644
--- a/drivers/tty/serial/stm32-usart.c
+++ b/drivers/tty/serial/stm32-usart.c
@@ -696,18 +696,23 @@ static void stm32_usart_transmit_chars_pio(struct uart_port *port)
 {
 	struct stm32_port *stm32_port = to_stm32_port(port);
 	const struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
-	struct circ_buf *xmit = &port->state->xmit;
+	struct tty_port *tport = &port->state->port;
+
+	while (1) {
+		unsigned char ch;
 
-	while (!uart_circ_empty(xmit)) {
 		/* Check that TDR is empty before filling FIFO */
 		if (!(readl_relaxed(port->membase + ofs->isr) & USART_SR_TXE))
 			break;
-		writel_relaxed(xmit->buf[xmit->tail], port->membase + ofs->tdr);
-		uart_xmit_advance(port, 1);
+
+		if (!uart_fifo_get(port, &ch))
+			break;
+
+		writel_relaxed(ch, port->membase + ofs->tdr);
 	}
 
 	/* rely on TXE irq (mask or unmask) for sending remaining data */
-	if (uart_circ_empty(xmit))
+	if (kfifo_is_empty(&tport->xmit_fifo))
 		stm32_usart_tx_interrupt_disable(port);
 	else
 		stm32_usart_tx_interrupt_enable(port);
@@ -716,7 +721,7 @@ static void stm32_usart_transmit_chars_pio(struct uart_port *port)
 static void stm32_usart_transmit_chars_dma(struct uart_port *port)
 {
 	struct stm32_port *stm32port = to_stm32_port(port);
-	struct circ_buf *xmit = &port->state->xmit;
+	struct tty_port *tport = &port->state->port;
 	struct dma_async_tx_descriptor *desc = NULL;
 	unsigned int count;
 	int ret;
@@ -728,25 +733,8 @@ static void stm32_usart_transmit_chars_dma(struct uart_port *port)
 		return;
 	}
 
-	count = uart_circ_chars_pending(xmit);
-
-	if (count > TX_BUF_L)
-		count = TX_BUF_L;
-
-	if (xmit->tail < xmit->head) {
-		memcpy(&stm32port->tx_buf[0], &xmit->buf[xmit->tail], count);
-	} else {
-		size_t one = UART_XMIT_SIZE - xmit->tail;
-		size_t two;
-
-		if (one > count)
-			one = count;
-		two = count - one;
-
-		memcpy(&stm32port->tx_buf[0], &xmit->buf[xmit->tail], one);
-		if (two)
-			memcpy(&stm32port->tx_buf[one], &xmit->buf[0], two);
-	}
+	count =	kfifo_out_peek(&tport->xmit_fifo, &stm32port->tx_buf[0],
+			TX_BUF_L);
 
 	desc = dmaengine_prep_slave_single(stm32port->tx_ch,
 					   stm32port->tx_dma_buf,
@@ -792,14 +780,14 @@ static void stm32_usart_transmit_chars(struct uart_port *port)
 {
 	struct stm32_port *stm32_port = to_stm32_port(port);
 	const struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
-	struct circ_buf *xmit = &port->state->xmit;
+	struct tty_port *tport = &port->state->port;
 	u32 isr;
 	int ret;
 
 	if (!stm32_port->hw_flow_control &&
 	    port->rs485.flags & SER_RS485_ENABLED &&
 	    (port->x_char ||
-	     !(uart_circ_empty(xmit) || uart_tx_stopped(port)))) {
+	     !(kfifo_is_empty(&tport->xmit_fifo) || uart_tx_stopped(port)))) {
 		stm32_usart_tc_interrupt_disable(port);
 		stm32_usart_rs485_rts_enable(port);
 	}
@@ -826,7 +814,7 @@ static void stm32_usart_transmit_chars(struct uart_port *port)
 		return;
 	}
 
-	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
+	if (kfifo_is_empty(&tport->xmit_fifo) || uart_tx_stopped(port)) {
 		stm32_usart_tx_interrupt_disable(port);
 		return;
 	}
@@ -841,10 +829,10 @@ static void stm32_usart_transmit_chars(struct uart_port *port)
 	else
 		stm32_usart_transmit_chars_pio(port);
 
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+	if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)
 		uart_write_wakeup(port);
 
-	if (uart_circ_empty(xmit)) {
+	if (kfifo_is_empty(&tport->xmit_fifo)) {
 		stm32_usart_tx_interrupt_disable(port);
 		if (!stm32_port->hw_flow_control &&
 		    port->rs485.flags & SER_RS485_ENABLED) {
@@ -975,9 +963,9 @@ static void stm32_usart_stop_tx(struct uart_port *port)
 /* There are probably characters waiting to be transmitted. */
 static void stm32_usart_start_tx(struct uart_port *port)
 {
-	struct circ_buf *xmit = &port->state->xmit;
+	struct tty_port *tport = &port->state->port;
 
-	if (uart_circ_empty(xmit) && !port->x_char) {
+	if (kfifo_is_empty(&tport->xmit_fifo) && !port->x_char) {
 		stm32_usart_rs485_rts_disable(port);
 		return;
 	}
diff --git a/drivers/tty/serial/sunhv.c b/drivers/tty/serial/sunhv.c
index 8d612ab806..7f60679fdd 100644
--- a/drivers/tty/serial/sunhv.c
+++ b/drivers/tty/serial/sunhv.c
@@ -39,10 +39,13 @@ static char *con_read_page;
 
 static int hung_up = 0;
 
-static void transmit_chars_putchar(struct uart_port *port, struct circ_buf *xmit)
+static void transmit_chars_putchar(struct uart_port *port,
+		struct tty_port *tport)
 {
-	while (!uart_circ_empty(xmit)) {
-		long status = sun4v_con_putchar(xmit->buf[xmit->tail]);
+	unsigned char ch;
+
+	while (kfifo_peek(&tport->xmit_fifo, &ch)) {
+		long status = sun4v_con_putchar(ch);
 
 		if (status != HV_EOK)
 			break;
@@ -51,14 +54,16 @@ static void transmit_chars_putchar(struct uart_port *port, struct circ_buf *xmit
 	}
 }
 
-static void transmit_chars_write(struct uart_port *port, struct circ_buf *xmit)
+static void transmit_chars_write(struct uart_port *port, struct tty_port *tport)
 {
-	while (!uart_circ_empty(xmit)) {
-		unsigned long ra = __pa(xmit->buf + xmit->tail);
-		unsigned long len, status, sent;
+	while (!kfifo_is_empty(&tport->xmit_fifo)) {
+		unsigned long len, ra, status, sent;
+		unsigned char *tail;
+
+		len = kfifo_out_linear_ptr(&tport->xmit_fifo, &tail,
+				UART_XMIT_SIZE);
+		ra = __pa(tail);
 
-		len = CIRC_CNT_TO_END(xmit->head, xmit->tail,
-				      UART_XMIT_SIZE);
 		status = sun4v_con_write(ra, len, &sent);
 		if (status != HV_EOK)
 			break;
@@ -165,7 +170,7 @@ static int receive_chars_read(struct uart_port *port)
 }
 
 struct sunhv_ops {
-	void (*transmit_chars)(struct uart_port *port, struct circ_buf *xmit);
+	void (*transmit_chars)(struct uart_port *port, struct tty_port *tport);
 	int (*receive_chars)(struct uart_port *port);
 };
 
@@ -196,18 +201,18 @@ static struct tty_port *receive_chars(struct uart_port *port)
 
 static void transmit_chars(struct uart_port *port)
 {
-	struct circ_buf *xmit;
+	struct tty_port *tport;
 
 	if (!port->state)
 		return;
 
-	xmit = &port->state->xmit;
-	if (uart_circ_empty(xmit) || uart_tx_stopped(port))
+	tport = &port->state->port;
+	if (kfifo_is_empty(&tport->xmit_fifo) || uart_tx_stopped(port))
 		return;
 
-	sunhv_ops->transmit_chars(port, xmit);
+	sunhv_ops->transmit_chars(port, tport);
 
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+	if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)
 		uart_write_wakeup(port);
 }
 
diff --git a/drivers/tty/serial/sunplus-uart.c b/drivers/tty/serial/sunplus-uart.c
index f5e29eb4a4..abf7c44930 100644
--- a/drivers/tty/serial/sunplus-uart.c
+++ b/drivers/tty/serial/sunplus-uart.c
@@ -200,7 +200,7 @@ static void sunplus_break_ctl(struct uart_port *port, int ctl)
 
 static void transmit_chars(struct uart_port *port)
 {
-	struct circ_buf *xmit = &port->state->xmit;
+	struct tty_port *tport = &port->state->port;
 
 	if (port->x_char) {
 		sp_uart_put_char(port, port->x_char);
@@ -209,22 +209,24 @@ static void transmit_chars(struct uart_port *port)
 		return;
 	}
 
-	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
+	if (kfifo_is_empty(&tport->xmit_fifo) || uart_tx_stopped(port)) {
 		sunplus_stop_tx(port);
 		return;
 	}
 
 	do {
-		sp_uart_put_char(port, xmit->buf[xmit->tail]);
-		uart_xmit_advance(port, 1);
-		if (uart_circ_empty(xmit))
+		unsigned char ch;
+
+		if (!uart_fifo_get(port, &ch))
 			break;
+
+		sp_uart_put_char(port, ch);
 	} while (sunplus_tx_buf_not_full(port));
 
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+	if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)
 		uart_write_wakeup(port);
 
-	if (uart_circ_empty(xmit))
+	if (kfifo_is_empty(&tport->xmit_fifo))
 		sunplus_stop_tx(port);
 }
 
diff --git a/drivers/tty/serial/sunsab.c b/drivers/tty/serial/sunsab.c
index 1ea2f33a07..1acbe2fba7 100644
--- a/drivers/tty/serial/sunsab.c
+++ b/drivers/tty/serial/sunsab.c
@@ -232,7 +232,7 @@ static void sunsab_tx_idle(struct uart_sunsab_port *);
 static void transmit_chars(struct uart_sunsab_port *up,
 			   union sab82532_irq_status *stat)
 {
-	struct circ_buf *xmit = &up->port.state->xmit;
+	struct tty_port *tport = &up->port.state->port;
 	int i;
 
 	if (stat->sreg.isr1 & SAB82532_ISR1_ALLS) {
@@ -252,7 +252,7 @@ static void transmit_chars(struct uart_sunsab_port *up,
 	set_bit(SAB82532_XPR, &up->irqflags);
 	sunsab_tx_idle(up);
 
-	if (uart_circ_empty(xmit) || uart_tx_stopped(&up->port)) {
+	if (kfifo_is_empty(&tport->xmit_fifo) || uart_tx_stopped(&up->port)) {
 		up->interrupt_mask1 |= SAB82532_IMR1_XPR;
 		writeb(up->interrupt_mask1, &up->regs->w.imr1);
 		return;
@@ -265,21 +265,22 @@ static void transmit_chars(struct uart_sunsab_port *up,
 	/* Stuff 32 bytes into Transmit FIFO. */
 	clear_bit(SAB82532_XPR, &up->irqflags);
 	for (i = 0; i < up->port.fifosize; i++) {
-		writeb(xmit->buf[xmit->tail],
-		       &up->regs->w.xfifo[i]);
-		uart_xmit_advance(&up->port, 1);
-		if (uart_circ_empty(xmit))
+		unsigned char ch;
+
+		if (!uart_fifo_get(&up->port, &ch))
 			break;
+
+		writeb(ch, &up->regs->w.xfifo[i]);
 	}
 
 	/* Issue a Transmit Frame command. */
 	sunsab_cec_wait(up);
 	writeb(SAB82532_CMDR_XF, &up->regs->w.cmdr);
 
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+	if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)
 		uart_write_wakeup(&up->port);
 
-	if (uart_circ_empty(xmit))
+	if (kfifo_is_empty(&tport->xmit_fifo))
 		sunsab_stop_tx(&up->port);
 }
 
@@ -435,10 +436,10 @@ static void sunsab_start_tx(struct uart_port *port)
 {
 	struct uart_sunsab_port *up =
 		container_of(port, struct uart_sunsab_port, port);
-	struct circ_buf *xmit = &up->port.state->xmit;
+	struct tty_port *tport = &up->port.state->port;
 	int i;
 
-	if (uart_circ_empty(xmit) || uart_tx_stopped(port))
+	if (kfifo_is_empty(&tport->xmit_fifo) || uart_tx_stopped(port))
 		return;
 
 	up->interrupt_mask1 &= ~(SAB82532_IMR1_ALLS|SAB82532_IMR1_XPR);
@@ -451,11 +452,12 @@ static void sunsab_start_tx(struct uart_port *port)
 	clear_bit(SAB82532_XPR, &up->irqflags);
 
 	for (i = 0; i < up->port.fifosize; i++) {
-		writeb(xmit->buf[xmit->tail],
-		       &up->regs->w.xfifo[i]);
-		uart_xmit_advance(&up->port, 1);
-		if (uart_circ_empty(xmit))
+		unsigned char ch;
+
+		if (!uart_fifo_get(&up->port, &ch))
 			break;
+
+		writeb(ch, &up->regs->w.xfifo[i]);
 	}
 
 	/* Issue a Transmit Frame command.  */
diff --git a/drivers/tty/serial/sunsu.c b/drivers/tty/serial/sunsu.c
index c8b65f4b27..67a5fc70bb 100644
--- a/drivers/tty/serial/sunsu.c
+++ b/drivers/tty/serial/sunsu.c
@@ -396,7 +396,8 @@ receive_chars(struct uart_sunsu_port *up, unsigned char *status)
 
 static void transmit_chars(struct uart_sunsu_port *up)
 {
-	struct circ_buf *xmit = &up->port.state->xmit;
+	struct tty_port *tport = &up->port.state->port;
+	unsigned char ch;
 	int count;
 
 	if (up->port.x_char) {
@@ -409,23 +410,23 @@ static void transmit_chars(struct uart_sunsu_port *up)
 		sunsu_stop_tx(&up->port);
 		return;
 	}
-	if (uart_circ_empty(xmit)) {
+	if (kfifo_is_empty(&tport->xmit_fifo)) {
 		__stop_tx(up);
 		return;
 	}
 
 	count = up->port.fifosize;
 	do {
-		serial_out(up, UART_TX, xmit->buf[xmit->tail]);
-		uart_xmit_advance(&up->port, 1);
-		if (uart_circ_empty(xmit))
+		if (!uart_fifo_get(&up->port, &ch))
 			break;
+
+		serial_out(up, UART_TX, ch);
 	} while (--count > 0);
 
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+	if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)
 		uart_write_wakeup(&up->port);
 
-	if (uart_circ_empty(xmit))
+	if (kfifo_is_empty(&tport->xmit_fifo))
 		__stop_tx(up);
 }
 
diff --git a/drivers/tty/serial/sunzilog.c b/drivers/tty/serial/sunzilog.c
index c99289c6c8..71758ad424 100644
--- a/drivers/tty/serial/sunzilog.c
+++ b/drivers/tty/serial/sunzilog.c
@@ -453,7 +453,8 @@ static void sunzilog_status_handle(struct uart_sunzilog_port *up,
 static void sunzilog_transmit_chars(struct uart_sunzilog_port *up,
 				    struct zilog_channel __iomem *channel)
 {
-	struct circ_buf *xmit;
+	struct tty_port *tport;
+	unsigned char ch;
 
 	if (ZS_IS_CONS(up)) {
 		unsigned char status = readb(&channel->control);
@@ -496,21 +497,20 @@ static void sunzilog_transmit_chars(struct uart_sunzilog_port *up,
 
 	if (up->port.state == NULL)
 		goto ack_tx_int;
-	xmit = &up->port.state->xmit;
-	if (uart_circ_empty(xmit))
-		goto ack_tx_int;
+	tport = &up->port.state->port;
 
 	if (uart_tx_stopped(&up->port))
 		goto ack_tx_int;
 
+	if (!uart_fifo_get(&up->port, &ch))
+		goto ack_tx_int;
+
 	up->flags |= SUNZILOG_FLAG_TX_ACTIVE;
-	writeb(xmit->buf[xmit->tail], &channel->data);
+	writeb(ch, &channel->data);
 	ZSDELAY();
 	ZS_WSYNC(channel);
 
-	uart_xmit_advance(&up->port, 1);
-
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+	if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)
 		uart_write_wakeup(&up->port);
 
 	return;
@@ -700,17 +700,16 @@ static void sunzilog_start_tx(struct uart_port *port)
 		port->icount.tx++;
 		port->x_char = 0;
 	} else {
-		struct circ_buf *xmit = &port->state->xmit;
+		struct tty_port *tport = &port->state->port;
+		unsigned char ch;
 
-		if (uart_circ_empty(xmit))
+		if (!uart_fifo_get(&up->port, &ch))
 			return;
-		writeb(xmit->buf[xmit->tail], &channel->data);
+		writeb(ch, &channel->data);
 		ZSDELAY();
 		ZS_WSYNC(channel);
 
-		uart_xmit_advance(port, 1);
-
-		if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+		if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)
 			uart_write_wakeup(&up->port);
 	}
 }
diff --git a/drivers/tty/serial/tegra-tcu.c b/drivers/tty/serial/tegra-tcu.c
index d9c78320eb..21ca5fcadf 100644
--- a/drivers/tty/serial/tegra-tcu.c
+++ b/drivers/tty/serial/tegra-tcu.c
@@ -91,15 +91,17 @@ static void tegra_tcu_write(struct tegra_tcu *tcu, const char *s,
 static void tegra_tcu_uart_start_tx(struct uart_port *port)
 {
 	struct tegra_tcu *tcu = port->private_data;
-	struct circ_buf *xmit = &port->state->xmit;
-	unsigned long count;
+	struct tty_port *tport = &port->state->port;
+	unsigned char *tail;
+	unsigned int count;
 
 	for (;;) {
-		count = CIRC_CNT_TO_END(xmit->head, xmit->tail, UART_XMIT_SIZE);
+		count = kfifo_out_linear_ptr(&tport->xmit_fifo, &tail,
+				UART_XMIT_SIZE);
 		if (!count)
 			break;
 
-		tegra_tcu_write(tcu, &xmit->buf[xmit->tail], count);
+		tegra_tcu_write(tcu, tail, count);
 		uart_xmit_advance(port, count);
 	}
 
diff --git a/drivers/tty/serial/timbuart.c b/drivers/tty/serial/timbuart.c
index 4bc89a9b38..43fa0938b5 100644
--- a/drivers/tty/serial/timbuart.c
+++ b/drivers/tty/serial/timbuart.c
@@ -95,14 +95,11 @@ static void timbuart_rx_chars(struct uart_port *port)
 
 static void timbuart_tx_chars(struct uart_port *port)
 {
-	struct circ_buf *xmit = &port->state->xmit;
+	unsigned char ch;
 
 	while (!(ioread32(port->membase + TIMBUART_ISR) & TXBF) &&
-		!uart_circ_empty(xmit)) {
-		iowrite8(xmit->buf[xmit->tail],
-			port->membase + TIMBUART_TXFIFO);
-		uart_xmit_advance(port, 1);
-	}
+			uart_fifo_get(port, &ch))
+		iowrite8(ch, port->membase + TIMBUART_TXFIFO);
 
 	dev_dbg(port->dev,
 		"%s - total written %d bytes, CTL: %x, RTS: %x, baud: %x\n",
@@ -117,9 +114,9 @@ static void timbuart_handle_tx_port(struct uart_port *port, u32 isr, u32 *ier)
 {
 	struct timbuart_port *uart =
 		container_of(port, struct timbuart_port, port);
-	struct circ_buf *xmit = &port->state->xmit;
+	struct tty_port *tport = &port->state->port;
 
-	if (uart_circ_empty(xmit) || uart_tx_stopped(port))
+	if (kfifo_is_empty(&tport->xmit_fifo) || uart_tx_stopped(port))
 		return;
 
 	if (port->x_char)
@@ -130,7 +127,7 @@ static void timbuart_handle_tx_port(struct uart_port *port, u32 isr, u32 *ier)
 		/* clear all TX interrupts */
 		iowrite32(TXFLAGS, port->membase + TIMBUART_ISR);
 
-		if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+		if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)
 			uart_write_wakeup(port);
 	} else
 		/* Re-enable any tx interrupt */
@@ -141,7 +138,7 @@ static void timbuart_handle_tx_port(struct uart_port *port, u32 isr, u32 *ier)
 	 * we wake up the upper layer later when we got the interrupt
 	 * to give it some time to go out...
 	 */
-	if (!uart_circ_empty(xmit))
+	if (!kfifo_is_empty(&tport->xmit_fifo))
 		*ier |= TXBAE;
 
 	dev_dbg(port->dev, "%s - leaving\n", __func__);
diff --git a/drivers/tty/serial/uartlite.c b/drivers/tty/serial/uartlite.c
index 10ba41b7be..68357ac8ff 100644
--- a/drivers/tty/serial/uartlite.c
+++ b/drivers/tty/serial/uartlite.c
@@ -189,7 +189,8 @@ static int ulite_receive(struct uart_port *port, int stat)
 
 static int ulite_transmit(struct uart_port *port, int stat)
 {
-	struct circ_buf *xmit  = &port->state->xmit;
+	struct tty_port *tport = &port->state->port;
+	unsigned char ch;
 
 	if (stat & ULITE_STATUS_TXFULL)
 		return 0;
@@ -201,14 +202,16 @@ static int ulite_transmit(struct uart_port *port, int stat)
 		return 1;
 	}
 
-	if (uart_circ_empty(xmit) || uart_tx_stopped(port))
+	if (uart_tx_stopped(port))
+		return 0;
+
+	if (!uart_fifo_get(port, &ch))
 		return 0;
 
-	uart_out32(xmit->buf[xmit->tail], ULITE_TX, port);
-	uart_xmit_advance(port, 1);
+	uart_out32(ch, ULITE_TX, port);
 
 	/* wake up */
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+	if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)
 		uart_write_wakeup(port);
 
 	return 1;
diff --git a/drivers/tty/serial/ucc_uart.c b/drivers/tty/serial/ucc_uart.c
index 397b95dff7..53bb8c5ef4 100644
--- a/drivers/tty/serial/ucc_uart.c
+++ b/drivers/tty/serial/ucc_uart.c
@@ -334,7 +334,7 @@ static int qe_uart_tx_pump(struct uart_qe_port *qe_port)
 	unsigned char *p;
 	unsigned int count;
 	struct uart_port *port = &qe_port->port;
-	struct circ_buf *xmit = &port->state->xmit;
+	struct tty_port *tport = &port->state->port;
 
 	/* Handle xon/xoff */
 	if (port->x_char) {
@@ -358,7 +358,7 @@ static int qe_uart_tx_pump(struct uart_qe_port *qe_port)
 		return 1;
 	}
 
-	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
+	if (kfifo_is_empty(&tport->xmit_fifo) || uart_tx_stopped(port)) {
 		qe_uart_stop_tx(port);
 		return 0;
 	}
@@ -366,16 +366,10 @@ static int qe_uart_tx_pump(struct uart_qe_port *qe_port)
 	/* Pick next descriptor and fill from buffer */
 	bdp = qe_port->tx_cur;
 
-	while (!(ioread16be(&bdp->status) & BD_SC_READY) && !uart_circ_empty(xmit)) {
-		count = 0;
+	while (!(ioread16be(&bdp->status) & BD_SC_READY) &&
+	       !kfifo_is_empty(&tport->xmit_fifo)) {
 		p = qe2cpu_addr(ioread32be(&bdp->buf), qe_port);
-		while (count < qe_port->tx_fifosize) {
-			*p++ = xmit->buf[xmit->tail];
-			uart_xmit_advance(port, 1);
-			count++;
-			if (uart_circ_empty(xmit))
-				break;
-		}
+		count =	uart_fifo_out(port, p, qe_port->tx_fifosize);
 
 		iowrite16be(count, &bdp->length);
 		qe_setbits_be16(&bdp->status, BD_SC_READY);
@@ -388,10 +382,10 @@ static int qe_uart_tx_pump(struct uart_qe_port *qe_port)
 	}
 	qe_port->tx_cur = bdp;
 
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+	if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)
 		uart_write_wakeup(port);
 
-	if (uart_circ_empty(xmit)) {
+	if (kfifo_is_empty(&tport->xmit_fifo)) {
 		/* The kernel buffer is empty, so turn off TX interrupts.  We
 		   don't need to be told when the QE is finished transmitting
 		   the data. */
diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c
index 5f48ec37cb..2acfcea403 100644
--- a/drivers/tty/serial/xilinx_uartps.c
+++ b/drivers/tty/serial/xilinx_uartps.c
@@ -25,6 +25,7 @@
 #include <linux/gpio.h>
 #include <linux/gpio/consumer.h>
 #include <linux/delay.h>
+#include <linux/reset.h>
 
 #define CDNS_UART_TTY_NAME	"ttyPS"
 #define CDNS_UART_NAME		"xuartps"
@@ -198,6 +199,7 @@ MODULE_PARM_DESC(rx_timeout, "Rx timeout, 1-255");
  * @gpiod_rts:		Pointer to the gpio descriptor
  * @rs485_tx_started:	RS485 tx state
  * @tx_timer:		Timer for tx
+ * @rstc:		Pointer to the reset control
  */
 struct cdns_uart {
 	struct uart_port	*port;
@@ -211,6 +213,7 @@ struct cdns_uart {
 	struct gpio_desc	*gpiod_rts;
 	bool			rs485_tx_started;
 	struct hrtimer		tx_timer;
+	struct reset_control	*rstc;
 };
 struct cdns_platform_data {
 	u32 quirks;
@@ -425,32 +428,32 @@ static void cdns_uart_handle_tx(void *dev_id)
 {
 	struct uart_port *port = (struct uart_port *)dev_id;
 	struct cdns_uart *cdns_uart = port->private_data;
-	struct circ_buf *xmit = &port->state->xmit;
+	struct tty_port *tport = &port->state->port;
 	unsigned int numbytes;
+	unsigned char ch;
 
-	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
+	if (kfifo_is_empty(&tport->xmit_fifo) || uart_tx_stopped(port)) {
 		/* Disable the TX Empty interrupt */
 		writel(CDNS_UART_IXR_TXEMPTY, port->membase + CDNS_UART_IDR);
 		return;
 	}
 
 	numbytes = port->fifosize;
-	while (numbytes && !uart_circ_empty(xmit) &&
-	       !(readl(port->membase + CDNS_UART_SR) & CDNS_UART_SR_TXFULL)) {
-
-		writel(xmit->buf[xmit->tail], port->membase + CDNS_UART_FIFO);
-		uart_xmit_advance(port, 1);
+	while (numbytes &&
+	       !(readl(port->membase + CDNS_UART_SR) & CDNS_UART_SR_TXFULL) &&
+	       uart_fifo_get(port, &ch)) {
+		writel(ch, port->membase + CDNS_UART_FIFO);
 		numbytes--;
 	}
 
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+	if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)
 		uart_write_wakeup(port);
 
 	/* Enable the TX Empty interrupt */
 	writel(CDNS_UART_IXR_TXEMPTY, cdns_uart->port->membase + CDNS_UART_IER);
 
 	if (cdns_uart->port->rs485.flags & SER_RS485_ENABLED &&
-	    (uart_circ_empty(xmit) || uart_tx_stopped(port))) {
+	    (kfifo_is_empty(&tport->xmit_fifo) || uart_tx_stopped(port))) {
 		cdns_uart->tx_timer.function = &cdns_rs485_rx_callback;
 		hrtimer_start(&cdns_uart->tx_timer,
 			      ns_to_ktime(cdns_calc_after_tx_delay(cdns_uart)), HRTIMER_MODE_REL);
@@ -723,7 +726,7 @@ static void cdns_uart_start_tx(struct uart_port *port)
 	status |= CDNS_UART_CR_TX_EN;
 	writel(status, port->membase + CDNS_UART_CR);
 
-	if (uart_circ_empty(&port->state->xmit))
+	if (kfifo_is_empty(&port->state->port.xmit_fifo))
 		return;
 
 	/* Clear the TX Empty interrupt */
@@ -948,6 +951,10 @@ static int cdns_uart_startup(struct uart_port *port)
 
 	is_brk_support = cdns_uart->quirks & CDNS_UART_RXBS_SUPPORT;
 
+	ret = reset_control_deassert(cdns_uart->rstc);
+	if (ret)
+		return ret;
+
 	uart_port_lock_irqsave(port, &flags);
 
 	/* Disable the TX and RX */
@@ -1721,6 +1728,13 @@ static int cdns_uart_probe(struct platform_device *pdev)
 		dev_err(&pdev->dev, "clock name 'ref_clk' is deprecated.\n");
 	}
 
+	cdns_uart_data->rstc = devm_reset_control_get_optional_exclusive(&pdev->dev, NULL);
+	if (IS_ERR(cdns_uart_data->rstc)) {
+		rc = PTR_ERR(cdns_uart_data->rstc);
+		dev_err_probe(&pdev->dev, rc, "Cannot get UART reset\n");
+		goto err_out_unregister_driver;
+	}
+
 	rc = clk_prepare_enable(cdns_uart_data->pclk);
 	if (rc) {
 		dev_err(&pdev->dev, "Unable to enable pclk clock.\n");
@@ -1881,6 +1895,7 @@ static void cdns_uart_remove(struct platform_device *pdev)
 	if (console_port == port)
 		console_port = NULL;
 #endif
+	reset_control_assert(cdns_uart_data->rstc);
 
 	if (!--instances)
 		uart_unregister_driver(cdns_uart_data->cdns_uart_driver);
diff --git a/drivers/tty/serial/zs.c b/drivers/tty/serial/zs.c
index 65ca4da6e3..79ea7108a0 100644
--- a/drivers/tty/serial/zs.c
+++ b/drivers/tty/serial/zs.c
@@ -606,7 +606,8 @@ static void zs_receive_chars(struct zs_port *zport)
 
 static void zs_raw_transmit_chars(struct zs_port *zport)
 {
-	struct circ_buf *xmit = &zport->port.state->xmit;
+	struct tty_port *tport = &zport->port.state->port;
+	unsigned char ch;
 
 	/* XON/XOFF chars.  */
 	if (zport->port.x_char) {
@@ -617,20 +618,20 @@ static void zs_raw_transmit_chars(struct zs_port *zport)
 	}
 
 	/* If nothing to do or stopped or hardware stopped.  */
-	if (uart_circ_empty(xmit) || uart_tx_stopped(&zport->port)) {
+	if (uart_tx_stopped(&zport->port) ||
+			!uart_fifo_get(&zport->port, &ch)) {
 		zs_raw_stop_tx(zport);
 		return;
 	}
 
 	/* Send char.  */
-	write_zsdata(zport, xmit->buf[xmit->tail]);
-	uart_xmit_advance(&zport->port, 1);
+	write_zsdata(zport, ch);
 
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+	if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)
 		uart_write_wakeup(&zport->port);
 
 	/* Are we are done?  */
-	if (uart_circ_empty(xmit))
+	if (kfifo_is_empty(&tport->xmit_fifo))
 		zs_raw_stop_tx(zport);
 }