Adding upstream version 6.6.15.upstream/6.6.15

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

1 files changed, 2672 insertions, 0 deletions

diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
new file mode 100644
index 0000000000..2fbb9b5977
--- /dev/null
+++ b/drivers/tty/serial/imx.c
@@ -0,0 +1,2672 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Driver for Motorola/Freescale IMX serial ports
+ *
+ * Based on drivers/char/serial.c, by Linus Torvalds, Theodore Ts'o.
+ *
+ * Author: Sascha Hauer <sascha@saschahauer.de>
+ * Copyright (C) 2004 Pengutronix
+ */
+
+#include <linux/module.h>
+#include <linux/ioport.h>
+#include <linux/init.h>
+#include <linux/console.h>
+#include <linux/sysrq.h>
+#include <linux/platform_device.h>
+#include <linux/tty.h>
+#include <linux/tty_flip.h>
+#include <linux/serial_core.h>
+#include <linux/serial.h>
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/ktime.h>
+#include <linux/pinctrl/consumer.h>
+#include <linux/rational.h>
+#include <linux/slab.h>
+#include <linux/of.h>
+#include <linux/io.h>
+#include <linux/dma-mapping.h>
+
+#include <asm/irq.h>
+#include <linux/dma/imx-dma.h>
+
+#include "serial_mctrl_gpio.h"
+
+/* Register definitions */
+#define URXD0 0x0  /* Receiver Register */
+#define URTX0 0x40 /* Transmitter Register */
+#define UCR1  0x80 /* Control Register 1 */
+#define UCR2  0x84 /* Control Register 2 */
+#define UCR3  0x88 /* Control Register 3 */
+#define UCR4  0x8c /* Control Register 4 */
+#define UFCR  0x90 /* FIFO Control Register */
+#define USR1  0x94 /* Status Register 1 */
+#define USR2  0x98 /* Status Register 2 */
+#define UESC  0x9c /* Escape Character Register */
+#define UTIM  0xa0 /* Escape Timer Register */
+#define UBIR  0xa4 /* BRM Incremental Register */
+#define UBMR  0xa8 /* BRM Modulator Register */
+#define UBRC  0xac /* Baud Rate Count Register */
+#define IMX21_ONEMS 0xb0 /* One Millisecond register */
+#define IMX1_UTS 0xd0 /* UART Test Register on i.mx1 */
+#define IMX21_UTS 0xb4 /* UART Test Register on all other i.mx*/
+
+/* UART Control Register Bit Fields.*/
+#define URXD_DUMMY_READ (1<<16)
+#define URXD_CHARRDY	(1<<15)
+#define URXD_ERR	(1<<14)
+#define URXD_OVRRUN	(1<<13)
+#define URXD_FRMERR	(1<<12)
+#define URXD_BRK	(1<<11)
+#define URXD_PRERR	(1<<10)
+#define URXD_RX_DATA	(0xFF<<0)
+#define UCR1_ADEN	(1<<15) /* Auto detect interrupt */
+#define UCR1_ADBR	(1<<14) /* Auto detect baud rate */
+#define UCR1_TRDYEN	(1<<13) /* Transmitter ready interrupt enable */
+#define UCR1_IDEN	(1<<12) /* Idle condition interrupt */
+#define UCR1_ICD_REG(x) (((x) & 3) << 10) /* idle condition detect */
+#define UCR1_RRDYEN	(1<<9)	/* Recv ready interrupt enable */
+#define UCR1_RXDMAEN	(1<<8)	/* Recv ready DMA enable */
+#define UCR1_IREN	(1<<7)	/* Infrared interface enable */
+#define UCR1_TXMPTYEN	(1<<6)	/* Transimitter empty interrupt enable */
+#define UCR1_RTSDEN	(1<<5)	/* RTS delta interrupt enable */
+#define UCR1_SNDBRK	(1<<4)	/* Send break */
+#define UCR1_TXDMAEN	(1<<3)	/* Transmitter ready DMA enable */
+#define IMX1_UCR1_UARTCLKEN (1<<2) /* UART clock enabled, i.mx1 only */
+#define UCR1_ATDMAEN    (1<<2)  /* Aging DMA Timer Enable */
+#define UCR1_DOZE	(1<<1)	/* Doze */
+#define UCR1_UARTEN	(1<<0)	/* UART enabled */
+#define UCR2_ESCI	(1<<15)	/* Escape seq interrupt enable */
+#define UCR2_IRTS	(1<<14)	/* Ignore RTS pin */
+#define UCR2_CTSC	(1<<13)	/* CTS pin control */
+#define UCR2_CTS	(1<<12)	/* Clear to send */
+#define UCR2_ESCEN	(1<<11)	/* Escape enable */
+#define UCR2_PREN	(1<<8)	/* Parity enable */
+#define UCR2_PROE	(1<<7)	/* Parity odd/even */
+#define UCR2_STPB	(1<<6)	/* Stop */
+#define UCR2_WS		(1<<5)	/* Word size */
+#define UCR2_RTSEN	(1<<4)	/* Request to send interrupt enable */
+#define UCR2_ATEN	(1<<3)	/* Aging Timer Enable */
+#define UCR2_TXEN	(1<<2)	/* Transmitter enabled */
+#define UCR2_RXEN	(1<<1)	/* Receiver enabled */
+#define UCR2_SRST	(1<<0)	/* SW reset */
+#define UCR3_DTREN	(1<<13) /* DTR interrupt enable */
+#define UCR3_PARERREN	(1<<12) /* Parity enable */
+#define UCR3_FRAERREN	(1<<11) /* Frame error interrupt enable */
+#define UCR3_DSR	(1<<10) /* Data set ready */
+#define UCR3_DCD	(1<<9)	/* Data carrier detect */
+#define UCR3_RI		(1<<8)	/* Ring indicator */
+#define UCR3_ADNIMP	(1<<7)	/* Autobaud Detection Not Improved */
+#define UCR3_RXDSEN	(1<<6)	/* Receive status interrupt enable */
+#define UCR3_AIRINTEN	(1<<5)	/* Async IR wake interrupt enable */
+#define UCR3_AWAKEN	(1<<4)	/* Async wake interrupt enable */
+#define UCR3_DTRDEN	(1<<3)	/* Data Terminal Ready Delta Enable. */
+#define IMX21_UCR3_RXDMUXSEL	(1<<2)	/* RXD Muxed Input Select */
+#define UCR3_INVT	(1<<1)	/* Inverted Infrared transmission */
+#define UCR3_BPEN	(1<<0)	/* Preset registers enable */
+#define UCR4_CTSTL_SHF	10	/* CTS trigger level shift */
+#define UCR4_CTSTL_MASK	0x3F	/* CTS trigger is 6 bits wide */
+#define UCR4_INVR	(1<<9)	/* Inverted infrared reception */
+#define UCR4_ENIRI	(1<<8)	/* Serial infrared interrupt enable */
+#define UCR4_WKEN	(1<<7)	/* Wake interrupt enable */
+#define UCR4_REF16	(1<<6)	/* Ref freq 16 MHz */
+#define UCR4_IDDMAEN    (1<<6)  /* DMA IDLE Condition Detected */
+#define UCR4_IRSC	(1<<5)	/* IR special case */
+#define UCR4_TCEN	(1<<3)	/* Transmit complete interrupt enable */
+#define UCR4_BKEN	(1<<2)	/* Break condition interrupt enable */
+#define UCR4_OREN	(1<<1)	/* Receiver overrun interrupt enable */
+#define UCR4_DREN	(1<<0)	/* Recv data ready interrupt enable */
+#define UFCR_RXTL_SHF	0	/* Receiver trigger level shift */
+#define UFCR_DCEDTE	(1<<6)	/* DCE/DTE mode select */
+#define UFCR_RFDIV	(7<<7)	/* Reference freq divider mask */
+#define UFCR_RFDIV_REG(x)	(((x) < 7 ? 6 - (x) : 6) << 7)
+#define UFCR_TXTL_SHF	10	/* Transmitter trigger level shift */
+#define USR1_PARITYERR	(1<<15) /* Parity error interrupt flag */
+#define USR1_RTSS	(1<<14) /* RTS pin status */
+#define USR1_TRDY	(1<<13) /* Transmitter ready interrupt/dma flag */
+#define USR1_RTSD	(1<<12) /* RTS delta */
+#define USR1_ESCF	(1<<11) /* Escape seq interrupt flag */
+#define USR1_FRAMERR	(1<<10) /* Frame error interrupt flag */
+#define USR1_RRDY	(1<<9)	 /* Receiver ready interrupt/dma flag */
+#define USR1_AGTIM	(1<<8)	 /* Ageing timer interrupt flag */
+#define USR1_DTRD	(1<<7)	 /* DTR Delta */
+#define USR1_RXDS	 (1<<6)	 /* Receiver idle interrupt flag */
+#define USR1_AIRINT	 (1<<5)	 /* Async IR wake interrupt flag */
+#define USR1_AWAKE	 (1<<4)	 /* Aysnc wake interrupt flag */
+#define USR2_ADET	 (1<<15) /* Auto baud rate detect complete */
+#define USR2_TXFE	 (1<<14) /* Transmit buffer FIFO empty */
+#define USR2_DTRF	 (1<<13) /* DTR edge interrupt flag */
+#define USR2_IDLE	 (1<<12) /* Idle condition */
+#define USR2_RIDELT	 (1<<10) /* Ring Interrupt Delta */
+#define USR2_RIIN	 (1<<9)	 /* Ring Indicator Input */
+#define USR2_IRINT	 (1<<8)	 /* Serial infrared interrupt flag */
+#define USR2_WAKE	 (1<<7)	 /* Wake */
+#define USR2_DCDIN	 (1<<5)	 /* Data Carrier Detect Input */
+#define USR2_RTSF	 (1<<4)	 /* RTS edge interrupt flag */
+#define USR2_TXDC	 (1<<3)	 /* Transmitter complete */
+#define USR2_BRCD	 (1<<2)	 /* Break condition */
+#define USR2_ORE	(1<<1)	 /* Overrun error */
+#define USR2_RDR	(1<<0)	 /* Recv data ready */
+#define UTS_FRCPERR	(1<<13) /* Force parity error */
+#define UTS_LOOP	(1<<12)	 /* Loop tx and rx */
+#define UTS_TXEMPTY	 (1<<6)	 /* TxFIFO empty */
+#define UTS_RXEMPTY	 (1<<5)	 /* RxFIFO empty */
+#define UTS_TXFULL	 (1<<4)	 /* TxFIFO full */
+#define UTS_RXFULL	 (1<<3)	 /* RxFIFO full */
+#define UTS_SOFTRST	 (1<<0)	 /* Software reset */
+
+/* We've been assigned a range on the "Low-density serial ports" major */
+#define SERIAL_IMX_MAJOR	207
+#define MINOR_START		16
+#define DEV_NAME		"ttymxc"
+
+/*
+ * This determines how often we check the modem status signals
+ * for any change.  They generally aren't connected to an IRQ
+ * so we have to poll them.  We also check immediately before
+ * filling the TX fifo incase CTS has been dropped.
+ */
+#define MCTRL_TIMEOUT	(250*HZ/1000)
+
+#define DRIVER_NAME "IMX-uart"
+
+#define UART_NR 8
+
+/* i.MX21 type uart runs on all i.mx except i.MX1 and i.MX6q */
+enum imx_uart_type {
+	IMX1_UART,
+	IMX21_UART,
+	IMX53_UART,
+	IMX6Q_UART,
+};
+
+/* device type dependent stuff */
+struct imx_uart_data {
+	unsigned uts_reg;
+	enum imx_uart_type devtype;
+};
+
+enum imx_tx_state {
+	OFF,
+	WAIT_AFTER_RTS,
+	SEND,
+	WAIT_AFTER_SEND,
+};
+
+struct imx_port {
+	struct uart_port	port;
+	struct timer_list	timer;
+	unsigned int		old_status;
+	unsigned int		have_rtscts:1;
+	unsigned int		have_rtsgpio:1;
+	unsigned int		dte_mode:1;
+	unsigned int		inverted_tx:1;
+	unsigned int		inverted_rx:1;
+	struct clk		*clk_ipg;
+	struct clk		*clk_per;
+	const struct imx_uart_data *devdata;
+
+	struct mctrl_gpios *gpios;
+
+	/* counter to stop 0xff flood */
+	int idle_counter;
+
+	/* DMA fields */
+	unsigned int		dma_is_enabled:1;
+	unsigned int		dma_is_rxing:1;
+	unsigned int		dma_is_txing:1;
+	struct dma_chan		*dma_chan_rx, *dma_chan_tx;
+	struct scatterlist	rx_sgl, tx_sgl[2];
+	void			*rx_buf;
+	struct circ_buf		rx_ring;
+	unsigned int		rx_buf_size;
+	unsigned int		rx_period_length;
+	unsigned int		rx_periods;
+	dma_cookie_t		rx_cookie;
+	unsigned int		tx_bytes;
+	unsigned int		dma_tx_nents;
+	unsigned int            saved_reg[10];
+	bool			context_saved;
+
+	enum imx_tx_state	tx_state;
+	struct hrtimer		trigger_start_tx;
+	struct hrtimer		trigger_stop_tx;
+};
+
+struct imx_port_ucrs {
+	unsigned int	ucr1;
+	unsigned int	ucr2;
+	unsigned int	ucr3;
+};
+
+static struct imx_uart_data imx_uart_devdata[] = {
+	[IMX1_UART] = {
+		.uts_reg = IMX1_UTS,
+		.devtype = IMX1_UART,
+	},
+	[IMX21_UART] = {
+		.uts_reg = IMX21_UTS,
+		.devtype = IMX21_UART,
+	},
+	[IMX53_UART] = {
+		.uts_reg = IMX21_UTS,
+		.devtype = IMX53_UART,
+	},
+	[IMX6Q_UART] = {
+		.uts_reg = IMX21_UTS,
+		.devtype = IMX6Q_UART,
+	},
+};
+
+static const struct of_device_id imx_uart_dt_ids[] = {
+	{ .compatible = "fsl,imx6q-uart", .data = &imx_uart_devdata[IMX6Q_UART], },
+	{ .compatible = "fsl,imx53-uart", .data = &imx_uart_devdata[IMX53_UART], },
+	{ .compatible = "fsl,imx1-uart", .data = &imx_uart_devdata[IMX1_UART], },
+	{ .compatible = "fsl,imx21-uart", .data = &imx_uart_devdata[IMX21_UART], },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, imx_uart_dt_ids);
+
+static inline void imx_uart_writel(struct imx_port *sport, u32 val, u32 offset)
+{
+	writel(val, sport->port.membase + offset);
+}
+
+static inline u32 imx_uart_readl(struct imx_port *sport, u32 offset)
+{
+	return readl(sport->port.membase + offset);
+}
+
+static inline unsigned imx_uart_uts_reg(struct imx_port *sport)
+{
+	return sport->devdata->uts_reg;
+}
+
+static inline int imx_uart_is_imx1(struct imx_port *sport)
+{
+	return sport->devdata->devtype == IMX1_UART;
+}
+
+/*
+ * Save and restore functions for UCR1, UCR2 and UCR3 registers
+ */
+#if IS_ENABLED(CONFIG_SERIAL_IMX_CONSOLE)
+static void imx_uart_ucrs_save(struct imx_port *sport,
+			       struct imx_port_ucrs *ucr)
+{
+	/* save control registers */
+	ucr->ucr1 = imx_uart_readl(sport, UCR1);
+	ucr->ucr2 = imx_uart_readl(sport, UCR2);
+	ucr->ucr3 = imx_uart_readl(sport, UCR3);
+}
+
+static void imx_uart_ucrs_restore(struct imx_port *sport,
+				  struct imx_port_ucrs *ucr)
+{
+	/* restore control registers */
+	imx_uart_writel(sport, ucr->ucr1, UCR1);
+	imx_uart_writel(sport, ucr->ucr2, UCR2);
+	imx_uart_writel(sport, ucr->ucr3, UCR3);
+}
+#endif
+
+/* called with port.lock taken and irqs caller dependent */
+static void imx_uart_rts_active(struct imx_port *sport, u32 *ucr2)
+{
+	*ucr2 &= ~(UCR2_CTSC | UCR2_CTS);
+
+	mctrl_gpio_set(sport->gpios, sport->port.mctrl | TIOCM_RTS);
+}
+
+/* called with port.lock taken and irqs caller dependent */
+static void imx_uart_rts_inactive(struct imx_port *sport, u32 *ucr2)
+{
+	*ucr2 &= ~UCR2_CTSC;
+	*ucr2 |= UCR2_CTS;
+
+	mctrl_gpio_set(sport->gpios, sport->port.mctrl & ~TIOCM_RTS);
+}
+
+static void start_hrtimer_ms(struct hrtimer *hrt, unsigned long msec)
+{
+       hrtimer_start(hrt, ms_to_ktime(msec), HRTIMER_MODE_REL);
+}
+
+/* called with port.lock taken and irqs off */
+static void imx_uart_soft_reset(struct imx_port *sport)
+{
+	int i = 10;
+	u32 ucr2, ubir, ubmr, uts;
+
+	/*
+	 * According to the Reference Manual description of the UART SRST bit:
+	 *
+	 * "Reset the transmit and receive state machines,
+	 * all FIFOs and register USR1, USR2, UBIR, UBMR, UBRC, URXD, UTXD
+	 * and UTS[6-3]".
+	 *
+	 * We don't need to restore the old values from USR1, USR2, URXD and
+	 * UTXD. UBRC is read only, so only save/restore the other three
+	 * registers.
+	 */
+	ubir = imx_uart_readl(sport, UBIR);
+	ubmr = imx_uart_readl(sport, UBMR);
+	uts = imx_uart_readl(sport, IMX21_UTS);
+
+	ucr2 = imx_uart_readl(sport, UCR2);
+	imx_uart_writel(sport, ucr2 & ~UCR2_SRST, UCR2);
+
+	while (!(imx_uart_readl(sport, UCR2) & UCR2_SRST) && (--i > 0))
+		udelay(1);
+
+	/* Restore the registers */
+	imx_uart_writel(sport, ubir, UBIR);
+	imx_uart_writel(sport, ubmr, UBMR);
+	imx_uart_writel(sport, uts, IMX21_UTS);
+
+	sport->idle_counter = 0;
+}
+
+static void imx_uart_disable_loopback_rs485(struct imx_port *sport)
+{
+	unsigned int uts;
+
+	/* See SER_RS485_ENABLED/UTS_LOOP comment in imx_uart_probe() */
+	uts = imx_uart_readl(sport, imx_uart_uts_reg(sport));
+	uts &= ~UTS_LOOP;
+	imx_uart_writel(sport, uts, imx_uart_uts_reg(sport));
+}
+
+/* called with port.lock taken and irqs off */
+static void imx_uart_start_rx(struct uart_port *port)
+{
+	struct imx_port *sport = (struct imx_port *)port;
+	unsigned int ucr1, ucr2;
+
+	ucr1 = imx_uart_readl(sport, UCR1);
+	ucr2 = imx_uart_readl(sport, UCR2);
+
+	ucr2 |= UCR2_RXEN;
+
+	if (sport->dma_is_enabled) {
+		ucr1 |= UCR1_RXDMAEN | UCR1_ATDMAEN;
+	} else {
+		ucr1 |= UCR1_RRDYEN;
+		ucr2 |= UCR2_ATEN;
+	}
+
+	/* Write UCR2 first as it includes RXEN */
+	imx_uart_writel(sport, ucr2, UCR2);
+	imx_uart_writel(sport, ucr1, UCR1);
+	imx_uart_disable_loopback_rs485(sport);
+}
+
+/* called with port.lock taken and irqs off */
+static void imx_uart_stop_tx(struct uart_port *port)
+{
+	struct imx_port *sport = (struct imx_port *)port;
+	u32 ucr1, ucr4, usr2;
+
+	if (sport->tx_state == OFF)
+		return;
+
+	/*
+	 * We are maybe in the SMP context, so if the DMA TX thread is running
+	 * on other cpu, we have to wait for it to finish.
+	 */
+	if (sport->dma_is_txing)
+		return;
+
+	ucr1 = imx_uart_readl(sport, UCR1);
+	imx_uart_writel(sport, ucr1 & ~UCR1_TRDYEN, UCR1);
+
+	ucr4 = imx_uart_readl(sport, UCR4);
+	usr2 = imx_uart_readl(sport, USR2);
+	if ((!(usr2 & USR2_TXDC)) && (ucr4 & UCR4_TCEN)) {
+		/* The shifter is still busy, so retry once TC triggers */
+		return;
+	}
+
+	ucr4 &= ~UCR4_TCEN;
+	imx_uart_writel(sport, ucr4, UCR4);
+
+	/* in rs485 mode disable transmitter */
+	if (port->rs485.flags & SER_RS485_ENABLED) {
+		if (sport->tx_state == SEND) {
+			sport->tx_state = WAIT_AFTER_SEND;
+
+			if (port->rs485.delay_rts_after_send > 0) {
+				start_hrtimer_ms(&sport->trigger_stop_tx,
+					 port->rs485.delay_rts_after_send);
+				return;
+			}
+
+			/* continue without any delay */
+		}
+
+		if (sport->tx_state == WAIT_AFTER_RTS ||
+		    sport->tx_state == WAIT_AFTER_SEND) {
+			u32 ucr2;
+
+			hrtimer_try_to_cancel(&sport->trigger_start_tx);
+
+			ucr2 = imx_uart_readl(sport, UCR2);
+			if (port->rs485.flags & SER_RS485_RTS_AFTER_SEND)
+				imx_uart_rts_active(sport, &ucr2);
+			else
+				imx_uart_rts_inactive(sport, &ucr2);
+			imx_uart_writel(sport, ucr2, UCR2);
+
+			if (!port->rs485_rx_during_tx_gpio)
+				imx_uart_start_rx(port);
+
+			sport->tx_state = OFF;
+		}
+	} else {
+		sport->tx_state = OFF;
+	}
+}
+
+/* called with port.lock taken and irqs off */
+static void imx_uart_stop_rx(struct uart_port *port)
+{
+	struct imx_port *sport = (struct imx_port *)port;
+	u32 ucr1, ucr2, ucr4, uts;
+
+	ucr1 = imx_uart_readl(sport, UCR1);
+	ucr2 = imx_uart_readl(sport, UCR2);
+	ucr4 = imx_uart_readl(sport, UCR4);
+
+	if (sport->dma_is_enabled) {
+		ucr1 &= ~(UCR1_RXDMAEN | UCR1_ATDMAEN);
+	} else {
+		ucr1 &= ~UCR1_RRDYEN;
+		ucr2 &= ~UCR2_ATEN;
+		ucr4 &= ~UCR4_OREN;
+	}
+	imx_uart_writel(sport, ucr1, UCR1);
+	imx_uart_writel(sport, ucr4, UCR4);
+
+	/* See SER_RS485_ENABLED/UTS_LOOP comment in imx_uart_probe() */
+	if (port->rs485.flags & SER_RS485_ENABLED &&
+	    port->rs485.flags & SER_RS485_RTS_ON_SEND &&
+	    sport->have_rtscts && !sport->have_rtsgpio) {
+		uts = imx_uart_readl(sport, imx_uart_uts_reg(sport));
+		uts |= UTS_LOOP;
+		imx_uart_writel(sport, uts, imx_uart_uts_reg(sport));
+		ucr2 |= UCR2_RXEN;
+	} else {
+		ucr2 &= ~UCR2_RXEN;
+	}
+
+	imx_uart_writel(sport, ucr2, UCR2);
+}
+
+/* called with port.lock taken and irqs off */
+static void imx_uart_enable_ms(struct uart_port *port)
+{
+	struct imx_port *sport = (struct imx_port *)port;
+
+	mod_timer(&sport->timer, jiffies);
+
+	mctrl_gpio_enable_ms(sport->gpios);
+}
+
+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;
+
+	if (sport->port.x_char) {
+		/* Send next char */
+		imx_uart_writel(sport, sport->port.x_char, URTX0);
+		sport->port.icount.tx++;
+		sport->port.x_char = 0;
+		return;
+	}
+
+	if (uart_circ_empty(xmit) || uart_tx_stopped(&sport->port)) {
+		imx_uart_stop_tx(&sport->port);
+		return;
+	}
+
+	if (sport->dma_is_enabled) {
+		u32 ucr1;
+		/*
+		 * We've just sent a X-char Ensure the TX DMA is enabled
+		 * and the TX IRQ is disabled.
+		 **/
+		ucr1 = imx_uart_readl(sport, UCR1);
+		ucr1 &= ~UCR1_TRDYEN;
+		if (sport->dma_is_txing) {
+			ucr1 |= UCR1_TXDMAEN;
+			imx_uart_writel(sport, ucr1, UCR1);
+		} else {
+			imx_uart_writel(sport, ucr1, UCR1);
+			imx_uart_dma_tx(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);
+	}
+
+	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+		uart_write_wakeup(&sport->port);
+
+	if (uart_circ_empty(xmit))
+		imx_uart_stop_tx(&sport->port);
+}
+
+static void imx_uart_dma_tx_callback(void *data)
+{
+	struct imx_port *sport = data;
+	struct scatterlist *sgl = &sport->tx_sgl[0];
+	struct circ_buf *xmit = &sport->port.state->xmit;
+	unsigned long flags;
+	u32 ucr1;
+
+	spin_lock_irqsave(&sport->port.lock, flags);
+
+	dma_unmap_sg(sport->port.dev, sgl, sport->dma_tx_nents, DMA_TO_DEVICE);
+
+	ucr1 = imx_uart_readl(sport, UCR1);
+	ucr1 &= ~UCR1_TXDMAEN;
+	imx_uart_writel(sport, ucr1, UCR1);
+
+	uart_xmit_advance(&sport->port, sport->tx_bytes);
+
+	dev_dbg(sport->port.dev, "we finish the TX DMA.\n");
+
+	sport->dma_is_txing = 0;
+
+	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+		uart_write_wakeup(&sport->port);
+
+	if (!uart_circ_empty(xmit) && !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);
+		ucr4 |= UCR4_TCEN;
+		imx_uart_writel(sport, ucr4, UCR4);
+	}
+
+	spin_unlock_irqrestore(&sport->port.lock, flags);
+}
+
+/* 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 scatterlist *sgl = sport->tx_sgl;
+	struct dma_async_tx_descriptor *desc;
+	struct dma_chan	*chan = sport->dma_chan_tx;
+	struct device *dev = sport->port.dev;
+	u32 ucr1, ucr4;
+	int ret;
+
+	if (sport->dma_is_txing)
+		return;
+
+	ucr4 = imx_uart_readl(sport, UCR4);
+	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);
+	}
+
+	ret = dma_map_sg(dev, sgl, sport->dma_tx_nents, DMA_TO_DEVICE);
+	if (ret == 0) {
+		dev_err(dev, "DMA mapping error for TX.\n");
+		return;
+	}
+	desc = dmaengine_prep_slave_sg(chan, sgl, ret,
+					DMA_MEM_TO_DEV, DMA_PREP_INTERRUPT);
+	if (!desc) {
+		dma_unmap_sg(dev, sgl, sport->dma_tx_nents,
+			     DMA_TO_DEVICE);
+		dev_err(dev, "We cannot prepare for the TX slave dma!\n");
+		return;
+	}
+	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));
+
+	ucr1 = imx_uart_readl(sport, UCR1);
+	ucr1 |= UCR1_TXDMAEN;
+	imx_uart_writel(sport, ucr1, UCR1);
+
+	/* fire it */
+	sport->dma_is_txing = 1;
+	dmaengine_submit(desc);
+	dma_async_issue_pending(chan);
+	return;
+}
+
+/* called with port.lock taken and irqs off */
+static void imx_uart_start_tx(struct uart_port *port)
+{
+	struct imx_port *sport = (struct imx_port *)port;
+	u32 ucr1;
+
+	if (!sport->port.x_char && uart_circ_empty(&port->state->xmit))
+		return;
+
+	/*
+	 * We cannot simply do nothing here if sport->tx_state == SEND already
+	 * because UCR1_TXMPTYEN might already have been cleared in
+	 * imx_uart_stop_tx(), but tx_state is still SEND.
+	 */
+
+	if (port->rs485.flags & SER_RS485_ENABLED) {
+		if (sport->tx_state == OFF) {
+			u32 ucr2 = imx_uart_readl(sport, UCR2);
+			if (port->rs485.flags & SER_RS485_RTS_ON_SEND)
+				imx_uart_rts_active(sport, &ucr2);
+			else
+				imx_uart_rts_inactive(sport, &ucr2);
+			imx_uart_writel(sport, ucr2, UCR2);
+
+			if (!(port->rs485.flags & SER_RS485_RX_DURING_TX) &&
+			    !port->rs485_rx_during_tx_gpio)
+				imx_uart_stop_rx(port);
+
+			sport->tx_state = WAIT_AFTER_RTS;
+
+			if (port->rs485.delay_rts_before_send > 0) {
+				start_hrtimer_ms(&sport->trigger_start_tx,
+					 port->rs485.delay_rts_before_send);
+				return;
+			}
+
+			/* continue without any delay */
+		}
+
+		if (sport->tx_state == WAIT_AFTER_SEND
+		    || sport->tx_state == WAIT_AFTER_RTS) {
+
+			hrtimer_try_to_cancel(&sport->trigger_stop_tx);
+
+			/*
+			 * Enable transmitter and shifter empty irq only if DMA
+			 * is off.  In the DMA case this is done in the
+			 * tx-callback.
+			 */
+			if (!sport->dma_is_enabled) {
+				u32 ucr4 = imx_uart_readl(sport, UCR4);
+				ucr4 |= UCR4_TCEN;
+				imx_uart_writel(sport, ucr4, UCR4);
+			}
+
+			sport->tx_state = SEND;
+		}
+	} else {
+		sport->tx_state = SEND;
+	}
+
+	if (!sport->dma_is_enabled) {
+		ucr1 = imx_uart_readl(sport, UCR1);
+		imx_uart_writel(sport, ucr1 | UCR1_TRDYEN, UCR1);
+	}
+
+	if (sport->dma_is_enabled) {
+		if (sport->port.x_char) {
+			/* We have X-char to send, so enable TX IRQ and
+			 * disable TX DMA to let TX interrupt to send X-char */
+			ucr1 = imx_uart_readl(sport, UCR1);
+			ucr1 &= ~UCR1_TXDMAEN;
+			ucr1 |= UCR1_TRDYEN;
+			imx_uart_writel(sport, ucr1, UCR1);
+			return;
+		}
+
+		if (!uart_circ_empty(&port->state->xmit) &&
+		    !uart_tx_stopped(port))
+			imx_uart_dma_tx(sport);
+		return;
+	}
+}
+
+static irqreturn_t __imx_uart_rtsint(int irq, void *dev_id)
+{
+	struct imx_port *sport = dev_id;
+	u32 usr1;
+
+	imx_uart_writel(sport, USR1_RTSD, USR1);
+	usr1 = imx_uart_readl(sport, USR1) & USR1_RTSS;
+	uart_handle_cts_change(&sport->port, usr1);
+	wake_up_interruptible(&sport->port.state->port.delta_msr_wait);
+
+	return IRQ_HANDLED;
+}
+
+static irqreturn_t imx_uart_rtsint(int irq, void *dev_id)
+{
+	struct imx_port *sport = dev_id;
+	irqreturn_t ret;
+
+	spin_lock(&sport->port.lock);
+
+	ret = __imx_uart_rtsint(irq, dev_id);
+
+	spin_unlock(&sport->port.lock);
+
+	return ret;
+}
+
+static irqreturn_t imx_uart_txint(int irq, void *dev_id)
+{
+	struct imx_port *sport = dev_id;
+
+	spin_lock(&sport->port.lock);
+	imx_uart_transmit_buffer(sport);
+	spin_unlock(&sport->port.lock);
+	return IRQ_HANDLED;
+}
+
+/* Check if hardware Rx flood is in progress, and issue soft reset to stop it.
+ * This is to be called from Rx ISRs only when some bytes were actually
+ * received.
+ *
+ * A way to reproduce the flood (checked on iMX6SX) is: open iMX UART at 9600
+ * 8N1, and from external source send 0xf0 char at 115200 8N1. In about 90% of
+ * cases this starts a flood of "receiving" of 0xff characters by the iMX6 UART
+ * that is terminated by any activity on RxD line, or could be stopped by
+ * issuing soft reset to the UART (just stop/start of RX does not help). Note
+ * that what we do here is sending isolated start bit about 2.4 times shorter
+ * than it is to be on UART configured baud rate.
+ */
+static void imx_uart_check_flood(struct imx_port *sport, u32 usr2)
+{
+	/* To detect hardware 0xff flood we monitor RxD line between RX
+	 * interrupts to isolate "receiving" of char(s) with no activity
+	 * on RxD line, that'd never happen on actual data transfers.
+	 *
+	 * We use USR2_WAKE bit to check for activity on RxD line, but we have a
+	 * race here if we clear USR2_WAKE when receiving of a char is in
+	 * progress, so we might get RX interrupt later with USR2_WAKE bit
+	 * cleared. Note though that as we don't try to clear USR2_WAKE when we
+	 * detected no activity, this race may hide actual activity only once.
+	 *
+	 * Yet another case where receive interrupt may occur without RxD
+	 * activity is expiration of aging timer, so we consider this as well.
+	 *
+	 * We use 'idle_counter' to ensure that we got at least so many RX
+	 * interrupts without any detected activity on RxD line. 2 cases
+	 * described plus 1 to be on the safe side gives us a margin of 3,
+	 * below. In practice I was not able to produce a false positive to
+	 * induce soft reset at regular data transfers even using 1 as the
+	 * margin, so 3 is actually very strong.
+	 *
+	 * We count interrupts, not chars in 'idle-counter' for simplicity.
+	 */
+
+	if (usr2 & USR2_WAKE) {
+		imx_uart_writel(sport, USR2_WAKE, USR2);
+		sport->idle_counter = 0;
+	} else if (++sport->idle_counter > 3) {
+		dev_warn(sport->port.dev, "RX flood detected: soft reset.");
+		imx_uart_soft_reset(sport); /* also clears 'sport->idle_counter' */
+	}
+}
+
+static irqreturn_t __imx_uart_rxint(int irq, void *dev_id)
+{
+	struct imx_port *sport = dev_id;
+	struct tty_port *port = &sport->port.state->port;
+	u32 usr2, rx;
+
+	/* If we received something, check for 0xff flood */
+	usr2 = imx_uart_readl(sport, USR2);
+	if (usr2 & USR2_RDR)
+		imx_uart_check_flood(sport, usr2);
+
+	while ((rx = imx_uart_readl(sport, URXD0)) & URXD_CHARRDY) {
+		unsigned int flg = TTY_NORMAL;
+		sport->port.icount.rx++;
+
+		if (unlikely(rx & URXD_ERR)) {
+			if (rx & URXD_BRK) {
+				sport->port.icount.brk++;
+				if (uart_handle_break(&sport->port))
+					continue;
+			}
+			else if (rx & URXD_PRERR)
+				sport->port.icount.parity++;
+			else if (rx & URXD_FRMERR)
+				sport->port.icount.frame++;
+			if (rx & URXD_OVRRUN)
+				sport->port.icount.overrun++;
+
+			if (rx & sport->port.ignore_status_mask)
+				continue;
+
+			rx &= (sport->port.read_status_mask | 0xFF);
+
+			if (rx & URXD_BRK)
+				flg = TTY_BREAK;
+			else if (rx & URXD_PRERR)
+				flg = TTY_PARITY;
+			else if (rx & URXD_FRMERR)
+				flg = TTY_FRAME;
+			if (rx & URXD_OVRRUN)
+				flg = TTY_OVERRUN;
+
+			sport->port.sysrq = 0;
+		} else if (uart_handle_sysrq_char(&sport->port, (unsigned char)rx)) {
+			continue;
+		}
+
+		if (sport->port.ignore_status_mask & URXD_DUMMY_READ)
+			continue;
+
+		if (tty_insert_flip_char(port, rx, flg) == 0)
+			sport->port.icount.buf_overrun++;
+	}
+
+	tty_flip_buffer_push(port);
+
+	return IRQ_HANDLED;
+}
+
+static irqreturn_t imx_uart_rxint(int irq, void *dev_id)
+{
+	struct imx_port *sport = dev_id;
+	irqreturn_t ret;
+
+	spin_lock(&sport->port.lock);
+
+	ret = __imx_uart_rxint(irq, dev_id);
+
+	spin_unlock(&sport->port.lock);
+
+	return ret;
+}
+
+static void imx_uart_clear_rx_errors(struct imx_port *sport);
+
+/*
+ * We have a modem side uart, so the meanings of RTS and CTS are inverted.
+ */
+static unsigned int imx_uart_get_hwmctrl(struct imx_port *sport)
+{
+	unsigned int tmp = TIOCM_DSR;
+	unsigned usr1 = imx_uart_readl(sport, USR1);
+	unsigned usr2 = imx_uart_readl(sport, USR2);
+
+	if (usr1 & USR1_RTSS)
+		tmp |= TIOCM_CTS;
+
+	/* in DCE mode DCDIN is always 0 */
+	if (!(usr2 & USR2_DCDIN))
+		tmp |= TIOCM_CAR;
+
+	if (sport->dte_mode)
+		if (!(imx_uart_readl(sport, USR2) & USR2_RIIN))
+			tmp |= TIOCM_RI;
+
+	return tmp;
+}
+
+/*
+ * Handle any change of modem status signal since we were last called.
+ */
+static void imx_uart_mctrl_check(struct imx_port *sport)
+{
+	unsigned int status, changed;
+
+	status = imx_uart_get_hwmctrl(sport);
+	changed = status ^ sport->old_status;
+
+	if (changed == 0)
+		return;
+
+	sport->old_status = status;
+
+	if (changed & TIOCM_RI && status & TIOCM_RI)
+		sport->port.icount.rng++;
+	if (changed & TIOCM_DSR)
+		sport->port.icount.dsr++;
+	if (changed & TIOCM_CAR)
+		uart_handle_dcd_change(&sport->port, status & TIOCM_CAR);
+	if (changed & TIOCM_CTS)
+		uart_handle_cts_change(&sport->port, status & TIOCM_CTS);
+
+	wake_up_interruptible(&sport->port.state->port.delta_msr_wait);
+}
+
+static irqreturn_t imx_uart_int(int irq, void *dev_id)
+{
+	struct imx_port *sport = dev_id;
+	unsigned int usr1, usr2, ucr1, ucr2, ucr3, ucr4;
+	irqreturn_t ret = IRQ_NONE;
+
+	spin_lock(&sport->port.lock);
+
+	usr1 = imx_uart_readl(sport, USR1);
+	usr2 = imx_uart_readl(sport, USR2);
+	ucr1 = imx_uart_readl(sport, UCR1);
+	ucr2 = imx_uart_readl(sport, UCR2);
+	ucr3 = imx_uart_readl(sport, UCR3);
+	ucr4 = imx_uart_readl(sport, UCR4);
+
+	/*
+	 * Even if a condition is true that can trigger an irq only handle it if
+	 * the respective irq source is enabled. This prevents some undesired
+	 * actions, for example if a character that sits in the RX FIFO and that
+	 * should be fetched via DMA is tried to be fetched using PIO. Or the
+	 * receiver is currently off and so reading from URXD0 results in an
+	 * exception. So just mask the (raw) status bits for disabled irqs.
+	 */
+	if ((ucr1 & UCR1_RRDYEN) == 0)
+		usr1 &= ~USR1_RRDY;
+	if ((ucr2 & UCR2_ATEN) == 0)
+		usr1 &= ~USR1_AGTIM;
+	if ((ucr1 & UCR1_TRDYEN) == 0)
+		usr1 &= ~USR1_TRDY;
+	if ((ucr4 & UCR4_TCEN) == 0)
+		usr2 &= ~USR2_TXDC;
+	if ((ucr3 & UCR3_DTRDEN) == 0)
+		usr1 &= ~USR1_DTRD;
+	if ((ucr1 & UCR1_RTSDEN) == 0)
+		usr1 &= ~USR1_RTSD;
+	if ((ucr3 & UCR3_AWAKEN) == 0)
+		usr1 &= ~USR1_AWAKE;
+	if ((ucr4 & UCR4_OREN) == 0)
+		usr2 &= ~USR2_ORE;
+
+	if (usr1 & (USR1_RRDY | USR1_AGTIM)) {
+		imx_uart_writel(sport, USR1_AGTIM, USR1);
+
+		__imx_uart_rxint(irq, dev_id);
+		ret = IRQ_HANDLED;
+	}
+
+	if ((usr1 & USR1_TRDY) || (usr2 & USR2_TXDC)) {
+		imx_uart_transmit_buffer(sport);
+		ret = IRQ_HANDLED;
+	}
+
+	if (usr1 & USR1_DTRD) {
+		imx_uart_writel(sport, USR1_DTRD, USR1);
+
+		imx_uart_mctrl_check(sport);
+
+		ret = IRQ_HANDLED;
+	}
+
+	if (usr1 & USR1_RTSD) {
+		__imx_uart_rtsint(irq, dev_id);
+		ret = IRQ_HANDLED;
+	}
+
+	if (usr1 & USR1_AWAKE) {
+		imx_uart_writel(sport, USR1_AWAKE, USR1);
+		ret = IRQ_HANDLED;
+	}
+
+	if (usr2 & USR2_ORE) {
+		sport->port.icount.overrun++;
+		imx_uart_writel(sport, USR2_ORE, USR2);
+		ret = IRQ_HANDLED;
+	}
+
+	spin_unlock(&sport->port.lock);
+
+	return ret;
+}
+
+/*
+ * Return TIOCSER_TEMT when transmitter is not busy.
+ */
+static unsigned int imx_uart_tx_empty(struct uart_port *port)
+{
+	struct imx_port *sport = (struct imx_port *)port;
+	unsigned int ret;
+
+	ret = (imx_uart_readl(sport, USR2) & USR2_TXDC) ?  TIOCSER_TEMT : 0;
+
+	/* If the TX DMA is working, return 0. */
+	if (sport->dma_is_txing)
+		ret = 0;
+
+	return ret;
+}
+
+/* called with port.lock taken and irqs off */
+static unsigned int imx_uart_get_mctrl(struct uart_port *port)
+{
+	struct imx_port *sport = (struct imx_port *)port;
+	unsigned int ret = imx_uart_get_hwmctrl(sport);
+
+	mctrl_gpio_get(sport->gpios, &ret);
+
+	return ret;
+}
+
+/* called with port.lock taken and irqs off */
+static void imx_uart_set_mctrl(struct uart_port *port, unsigned int mctrl)
+{
+	struct imx_port *sport = (struct imx_port *)port;
+	u32 ucr3, uts;
+
+	if (!(port->rs485.flags & SER_RS485_ENABLED)) {
+		u32 ucr2;
+
+		/*
+		 * Turn off autoRTS if RTS is lowered and restore autoRTS
+		 * setting if RTS is raised.
+		 */
+		ucr2 = imx_uart_readl(sport, UCR2);
+		ucr2 &= ~(UCR2_CTS | UCR2_CTSC);
+		if (mctrl & TIOCM_RTS) {
+			ucr2 |= UCR2_CTS;
+			/*
+			 * UCR2_IRTS is unset if and only if the port is
+			 * configured for CRTSCTS, so we use inverted UCR2_IRTS
+			 * to get the state to restore to.
+			 */
+			if (!(ucr2 & UCR2_IRTS))
+				ucr2 |= UCR2_CTSC;
+		}
+		imx_uart_writel(sport, ucr2, UCR2);
+	}
+
+	ucr3 = imx_uart_readl(sport, UCR3) & ~UCR3_DSR;
+	if (!(mctrl & TIOCM_DTR))
+		ucr3 |= UCR3_DSR;
+	imx_uart_writel(sport, ucr3, UCR3);
+
+	uts = imx_uart_readl(sport, imx_uart_uts_reg(sport)) & ~UTS_LOOP;
+	if (mctrl & TIOCM_LOOP)
+		uts |= UTS_LOOP;
+	imx_uart_writel(sport, uts, imx_uart_uts_reg(sport));
+
+	mctrl_gpio_set(sport->gpios, mctrl);
+}
+
+/*
+ * Interrupts always disabled.
+ */
+static void imx_uart_break_ctl(struct uart_port *port, int break_state)
+{
+	struct imx_port *sport = (struct imx_port *)port;
+	unsigned long flags;
+	u32 ucr1;
+
+	spin_lock_irqsave(&sport->port.lock, flags);
+
+	ucr1 = imx_uart_readl(sport, UCR1) & ~UCR1_SNDBRK;
+
+	if (break_state != 0)
+		ucr1 |= UCR1_SNDBRK;
+
+	imx_uart_writel(sport, ucr1, UCR1);
+
+	spin_unlock_irqrestore(&sport->port.lock, flags);
+}
+
+/*
+ * This is our per-port timeout handler, for checking the
+ * modem status signals.
+ */
+static void imx_uart_timeout(struct timer_list *t)
+{
+	struct imx_port *sport = from_timer(sport, t, timer);
+	unsigned long flags;
+
+	if (sport->port.state) {
+		spin_lock_irqsave(&sport->port.lock, flags);
+		imx_uart_mctrl_check(sport);
+		spin_unlock_irqrestore(&sport->port.lock, flags);
+
+		mod_timer(&sport->timer, jiffies + MCTRL_TIMEOUT);
+	}
+}
+
+/*
+ * There are two kinds of RX DMA interrupts(such as in the MX6Q):
+ *   [1] the RX DMA buffer is full.
+ *   [2] the aging timer expires
+ *
+ * Condition [2] is triggered when a character has been sitting in the FIFO
+ * for at least 8 byte durations.
+ */
+static void imx_uart_dma_rx_callback(void *data)
+{
+	struct imx_port *sport = data;
+	struct dma_chan	*chan = sport->dma_chan_rx;
+	struct scatterlist *sgl = &sport->rx_sgl;
+	struct tty_port *port = &sport->port.state->port;
+	struct dma_tx_state state;
+	struct circ_buf *rx_ring = &sport->rx_ring;
+	enum dma_status status;
+	unsigned int w_bytes = 0;
+	unsigned int r_bytes;
+	unsigned int bd_size;
+
+	status = dmaengine_tx_status(chan, sport->rx_cookie, &state);
+
+	if (status == DMA_ERROR) {
+		spin_lock(&sport->port.lock);
+		imx_uart_clear_rx_errors(sport);
+		spin_unlock(&sport->port.lock);
+		return;
+	}
+
+	/*
+	 * The state-residue variable represents the empty space
+	 * relative to the entire buffer. Taking this in consideration
+	 * the head is always calculated base on the buffer total
+	 * length - DMA transaction residue. The UART script from the
+	 * SDMA firmware will jump to the next buffer descriptor,
+	 * once a DMA transaction if finalized (IMX53 RM - A.4.1.2.4).
+	 * Taking this in consideration the tail is always at the
+	 * beginning of the buffer descriptor that contains the head.
+	 */
+
+	/* Calculate the head */
+	rx_ring->head = sg_dma_len(sgl) - state.residue;
+
+	/* Calculate the tail. */
+	bd_size = sg_dma_len(sgl) / sport->rx_periods;
+	rx_ring->tail = ((rx_ring->head-1) / bd_size) * bd_size;
+
+	if (rx_ring->head <= sg_dma_len(sgl) &&
+	    rx_ring->head > rx_ring->tail) {
+
+		/* Move data from tail to head */
+		r_bytes = rx_ring->head - rx_ring->tail;
+
+		/* If we received something, check for 0xff flood */
+		spin_lock(&sport->port.lock);
+		imx_uart_check_flood(sport, imx_uart_readl(sport, USR2));
+		spin_unlock(&sport->port.lock);
+
+		if (!(sport->port.ignore_status_mask & URXD_DUMMY_READ)) {
+
+			/* CPU claims ownership of RX DMA buffer */
+			dma_sync_sg_for_cpu(sport->port.dev, sgl, 1,
+					    DMA_FROM_DEVICE);
+
+			w_bytes = tty_insert_flip_string(port,
+							 sport->rx_buf + rx_ring->tail, r_bytes);
+
+			/* UART retrieves ownership of RX DMA buffer */
+			dma_sync_sg_for_device(sport->port.dev, sgl, 1,
+					       DMA_FROM_DEVICE);
+
+			if (w_bytes != r_bytes)
+				sport->port.icount.buf_overrun++;
+
+			sport->port.icount.rx += w_bytes;
+		}
+	} else	{
+		WARN_ON(rx_ring->head > sg_dma_len(sgl));
+		WARN_ON(rx_ring->head <= rx_ring->tail);
+	}
+
+	if (w_bytes) {
+		tty_flip_buffer_push(port);
+		dev_dbg(sport->port.dev, "We get %d bytes.\n", w_bytes);
+	}
+}
+
+static int imx_uart_start_rx_dma(struct imx_port *sport)
+{
+	struct scatterlist *sgl = &sport->rx_sgl;
+	struct dma_chan	*chan = sport->dma_chan_rx;
+	struct device *dev = sport->port.dev;
+	struct dma_async_tx_descriptor *desc;
+	int ret;
+
+	sport->rx_ring.head = 0;
+	sport->rx_ring.tail = 0;
+
+	sg_init_one(sgl, sport->rx_buf, sport->rx_buf_size);
+	ret = dma_map_sg(dev, sgl, 1, DMA_FROM_DEVICE);
+	if (ret == 0) {
+		dev_err(dev, "DMA mapping error for RX.\n");
+		return -EINVAL;
+	}
+
+	desc = dmaengine_prep_dma_cyclic(chan, sg_dma_address(sgl),
+		sg_dma_len(sgl), sg_dma_len(sgl) / sport->rx_periods,
+		DMA_DEV_TO_MEM, DMA_PREP_INTERRUPT);
+
+	if (!desc) {
+		dma_unmap_sg(dev, sgl, 1, DMA_FROM_DEVICE);
+		dev_err(dev, "We cannot prepare for the RX slave dma!\n");
+		return -EINVAL;
+	}
+	desc->callback = imx_uart_dma_rx_callback;
+	desc->callback_param = sport;
+
+	dev_dbg(dev, "RX: prepare for the DMA.\n");
+	sport->dma_is_rxing = 1;
+	sport->rx_cookie = dmaengine_submit(desc);
+	dma_async_issue_pending(chan);
+	return 0;
+}
+
+static void imx_uart_clear_rx_errors(struct imx_port *sport)
+{
+	struct tty_port *port = &sport->port.state->port;
+	u32 usr1, usr2;
+
+	usr1 = imx_uart_readl(sport, USR1);
+	usr2 = imx_uart_readl(sport, USR2);
+
+	if (usr2 & USR2_BRCD) {
+		sport->port.icount.brk++;
+		imx_uart_writel(sport, USR2_BRCD, USR2);
+		uart_handle_break(&sport->port);
+		if (tty_insert_flip_char(port, 0, TTY_BREAK) == 0)
+			sport->port.icount.buf_overrun++;
+		tty_flip_buffer_push(port);
+	} else {
+		if (usr1 & USR1_FRAMERR) {
+			sport->port.icount.frame++;
+			imx_uart_writel(sport, USR1_FRAMERR, USR1);
+		} else if (usr1 & USR1_PARITYERR) {
+			sport->port.icount.parity++;
+			imx_uart_writel(sport, USR1_PARITYERR, USR1);
+		}
+	}
+
+	if (usr2 & USR2_ORE) {
+		sport->port.icount.overrun++;
+		imx_uart_writel(sport, USR2_ORE, USR2);
+	}
+
+	sport->idle_counter = 0;
+
+}
+
+#define TXTL_DEFAULT 2 /* reset default */
+#define RXTL_DEFAULT 8 /* 8 characters or aging timer */
+#define TXTL_DMA 8 /* DMA burst setting */
+#define RXTL_DMA 9 /* DMA burst setting */
+
+static void imx_uart_setup_ufcr(struct imx_port *sport,
+				unsigned char txwl, unsigned char rxwl)
+{
+	unsigned int val;
+
+	/* set receiver / transmitter trigger level */
+	val = imx_uart_readl(sport, UFCR) & (UFCR_RFDIV | UFCR_DCEDTE);
+	val |= txwl << UFCR_TXTL_SHF | rxwl;
+	imx_uart_writel(sport, val, UFCR);
+}
+
+static void imx_uart_dma_exit(struct imx_port *sport)
+{
+	if (sport->dma_chan_rx) {
+		dmaengine_terminate_sync(sport->dma_chan_rx);
+		dma_release_channel(sport->dma_chan_rx);
+		sport->dma_chan_rx = NULL;
+		sport->rx_cookie = -EINVAL;
+		kfree(sport->rx_buf);
+		sport->rx_buf = NULL;
+	}
+
+	if (sport->dma_chan_tx) {
+		dmaengine_terminate_sync(sport->dma_chan_tx);
+		dma_release_channel(sport->dma_chan_tx);
+		sport->dma_chan_tx = NULL;
+	}
+}
+
+static int imx_uart_dma_init(struct imx_port *sport)
+{
+	struct dma_slave_config slave_config = {};
+	struct device *dev = sport->port.dev;
+	int ret;
+
+	/* Prepare for RX : */
+	sport->dma_chan_rx = dma_request_slave_channel(dev, "rx");
+	if (!sport->dma_chan_rx) {
+		dev_dbg(dev, "cannot get the DMA channel.\n");
+		ret = -EINVAL;
+		goto err;
+	}
+
+	slave_config.direction = DMA_DEV_TO_MEM;
+	slave_config.src_addr = sport->port.mapbase + URXD0;
+	slave_config.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
+	/* one byte less than the watermark level to enable the aging timer */
+	slave_config.src_maxburst = RXTL_DMA - 1;
+	ret = dmaengine_slave_config(sport->dma_chan_rx, &slave_config);
+	if (ret) {
+		dev_err(dev, "error in RX dma configuration.\n");
+		goto err;
+	}
+
+	sport->rx_buf_size = sport->rx_period_length * sport->rx_periods;
+	sport->rx_buf = kzalloc(sport->rx_buf_size, GFP_KERNEL);
+	if (!sport->rx_buf) {
+		ret = -ENOMEM;
+		goto err;
+	}
+	sport->rx_ring.buf = sport->rx_buf;
+
+	/* Prepare for TX : */
+	sport->dma_chan_tx = dma_request_slave_channel(dev, "tx");
+	if (!sport->dma_chan_tx) {
+		dev_err(dev, "cannot get the TX DMA channel!\n");
+		ret = -EINVAL;
+		goto err;
+	}
+
+	slave_config.direction = DMA_MEM_TO_DEV;
+	slave_config.dst_addr = sport->port.mapbase + URTX0;
+	slave_config.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
+	slave_config.dst_maxburst = TXTL_DMA;
+	ret = dmaengine_slave_config(sport->dma_chan_tx, &slave_config);
+	if (ret) {
+		dev_err(dev, "error in TX dma configuration.");
+		goto err;
+	}
+
+	return 0;
+err:
+	imx_uart_dma_exit(sport);
+	return ret;
+}
+
+static void imx_uart_enable_dma(struct imx_port *sport)
+{
+	u32 ucr1;
+
+	imx_uart_setup_ufcr(sport, TXTL_DMA, RXTL_DMA);
+
+	/* set UCR1 */
+	ucr1 = imx_uart_readl(sport, UCR1);
+	ucr1 |= UCR1_RXDMAEN | UCR1_TXDMAEN | UCR1_ATDMAEN;
+	imx_uart_writel(sport, ucr1, UCR1);
+
+	sport->dma_is_enabled = 1;
+}
+
+static void imx_uart_disable_dma(struct imx_port *sport)
+{
+	u32 ucr1;
+
+	/* clear UCR1 */
+	ucr1 = imx_uart_readl(sport, UCR1);
+	ucr1 &= ~(UCR1_RXDMAEN | UCR1_TXDMAEN | UCR1_ATDMAEN);
+	imx_uart_writel(sport, ucr1, UCR1);
+
+	imx_uart_setup_ufcr(sport, TXTL_DEFAULT, RXTL_DEFAULT);
+
+	sport->dma_is_enabled = 0;
+}
+
+/* half the RX buffer size */
+#define CTSTL 16
+
+static int imx_uart_startup(struct uart_port *port)
+{
+	struct imx_port *sport = (struct imx_port *)port;
+	int retval;
+	unsigned long flags;
+	int dma_is_inited = 0;
+	u32 ucr1, ucr2, ucr3, ucr4;
+
+	retval = clk_prepare_enable(sport->clk_per);
+	if (retval)
+		return retval;
+	retval = clk_prepare_enable(sport->clk_ipg);
+	if (retval) {
+		clk_disable_unprepare(sport->clk_per);
+		return retval;
+	}
+
+	imx_uart_setup_ufcr(sport, TXTL_DEFAULT, RXTL_DEFAULT);
+
+	/* disable the DREN bit (Data Ready interrupt enable) before
+	 * requesting IRQs
+	 */
+	ucr4 = imx_uart_readl(sport, UCR4);
+
+	/* set the trigger level for CTS */
+	ucr4 &= ~(UCR4_CTSTL_MASK << UCR4_CTSTL_SHF);
+	ucr4 |= CTSTL << UCR4_CTSTL_SHF;
+
+	imx_uart_writel(sport, ucr4 & ~UCR4_DREN, UCR4);
+
+	/* Can we enable the DMA support? */
+	if (!uart_console(port) && imx_uart_dma_init(sport) == 0)
+		dma_is_inited = 1;
+
+	spin_lock_irqsave(&sport->port.lock, flags);
+
+	/* Reset fifo's and state machines */
+	imx_uart_soft_reset(sport);
+
+	/*
+	 * Finally, clear and enable interrupts
+	 */
+	imx_uart_writel(sport, USR1_RTSD | USR1_DTRD, USR1);
+	imx_uart_writel(sport, USR2_ORE, USR2);
+
+	ucr1 = imx_uart_readl(sport, UCR1) & ~UCR1_RRDYEN;
+	ucr1 |= UCR1_UARTEN;
+	if (sport->have_rtscts)
+		ucr1 |= UCR1_RTSDEN;
+
+	imx_uart_writel(sport, ucr1, UCR1);
+
+	ucr4 = imx_uart_readl(sport, UCR4) & ~(UCR4_OREN | UCR4_INVR);
+	if (!dma_is_inited)
+		ucr4 |= UCR4_OREN;
+	if (sport->inverted_rx)
+		ucr4 |= UCR4_INVR;
+	imx_uart_writel(sport, ucr4, UCR4);
+
+	ucr3 = imx_uart_readl(sport, UCR3) & ~UCR3_INVT;
+	/*
+	 * configure tx polarity before enabling tx
+	 */
+	if (sport->inverted_tx)
+		ucr3 |= UCR3_INVT;
+
+	if (!imx_uart_is_imx1(sport)) {
+		ucr3 |= UCR3_DTRDEN | UCR3_RI | UCR3_DCD;
+
+		if (sport->dte_mode)
+			/* disable broken interrupts */
+			ucr3 &= ~(UCR3_RI | UCR3_DCD);
+	}
+	imx_uart_writel(sport, ucr3, UCR3);
+
+	ucr2 = imx_uart_readl(sport, UCR2) & ~UCR2_ATEN;
+	ucr2 |= (UCR2_RXEN | UCR2_TXEN);
+	if (!sport->have_rtscts)
+		ucr2 |= UCR2_IRTS;
+	/*
+	 * make sure the edge sensitive RTS-irq is disabled,
+	 * we're using RTSD instead.
+	 */
+	if (!imx_uart_is_imx1(sport))
+		ucr2 &= ~UCR2_RTSEN;
+	imx_uart_writel(sport, ucr2, UCR2);
+
+	/*
+	 * Enable modem status interrupts
+	 */
+	imx_uart_enable_ms(&sport->port);
+
+	if (dma_is_inited) {
+		imx_uart_enable_dma(sport);
+		imx_uart_start_rx_dma(sport);
+	} else {
+		ucr1 = imx_uart_readl(sport, UCR1);
+		ucr1 |= UCR1_RRDYEN;
+		imx_uart_writel(sport, ucr1, UCR1);
+
+		ucr2 = imx_uart_readl(sport, UCR2);
+		ucr2 |= UCR2_ATEN;
+		imx_uart_writel(sport, ucr2, UCR2);
+	}
+
+	imx_uart_disable_loopback_rs485(sport);
+
+	spin_unlock_irqrestore(&sport->port.lock, flags);
+
+	return 0;
+}
+
+static void imx_uart_shutdown(struct uart_port *port)
+{
+	struct imx_port *sport = (struct imx_port *)port;
+	unsigned long flags;
+	u32 ucr1, ucr2, ucr4, uts;
+
+	if (sport->dma_is_enabled) {
+		dmaengine_terminate_sync(sport->dma_chan_tx);
+		if (sport->dma_is_txing) {
+			dma_unmap_sg(sport->port.dev, &sport->tx_sgl[0],
+				     sport->dma_tx_nents, DMA_TO_DEVICE);
+			sport->dma_is_txing = 0;
+		}
+		dmaengine_terminate_sync(sport->dma_chan_rx);
+		if (sport->dma_is_rxing) {
+			dma_unmap_sg(sport->port.dev, &sport->rx_sgl,
+				     1, DMA_FROM_DEVICE);
+			sport->dma_is_rxing = 0;
+		}
+
+		spin_lock_irqsave(&sport->port.lock, flags);
+		imx_uart_stop_tx(port);
+		imx_uart_stop_rx(port);
+		imx_uart_disable_dma(sport);
+		spin_unlock_irqrestore(&sport->port.lock, flags);
+		imx_uart_dma_exit(sport);
+	}
+
+	mctrl_gpio_disable_ms(sport->gpios);
+
+	spin_lock_irqsave(&sport->port.lock, flags);
+	ucr2 = imx_uart_readl(sport, UCR2);
+	ucr2 &= ~(UCR2_TXEN | UCR2_ATEN);
+	imx_uart_writel(sport, ucr2, UCR2);
+	spin_unlock_irqrestore(&sport->port.lock, flags);
+
+	/*
+	 * Stop our timer.
+	 */
+	del_timer_sync(&sport->timer);
+
+	/*
+	 * Disable all interrupts, port and break condition.
+	 */
+
+	spin_lock_irqsave(&sport->port.lock, flags);
+
+	ucr1 = imx_uart_readl(sport, UCR1);
+	ucr1 &= ~(UCR1_TRDYEN | UCR1_RRDYEN | UCR1_RTSDEN | UCR1_RXDMAEN |
+		  UCR1_ATDMAEN | UCR1_SNDBRK);
+	/* See SER_RS485_ENABLED/UTS_LOOP comment in imx_uart_probe() */
+	if (port->rs485.flags & SER_RS485_ENABLED &&
+	    port->rs485.flags & SER_RS485_RTS_ON_SEND &&
+	    sport->have_rtscts && !sport->have_rtsgpio) {
+		uts = imx_uart_readl(sport, imx_uart_uts_reg(sport));
+		uts |= UTS_LOOP;
+		imx_uart_writel(sport, uts, imx_uart_uts_reg(sport));
+		ucr1 |= UCR1_UARTEN;
+	} else {
+		ucr1 &= ~UCR1_UARTEN;
+	}
+	imx_uart_writel(sport, ucr1, UCR1);
+
+	ucr4 = imx_uart_readl(sport, UCR4);
+	ucr4 &= ~UCR4_TCEN;
+	imx_uart_writel(sport, ucr4, UCR4);
+
+	spin_unlock_irqrestore(&sport->port.lock, flags);
+
+	clk_disable_unprepare(sport->clk_per);
+	clk_disable_unprepare(sport->clk_ipg);
+}
+
+/* called with port.lock taken and irqs off */
+static void imx_uart_flush_buffer(struct uart_port *port)
+{
+	struct imx_port *sport = (struct imx_port *)port;
+	struct scatterlist *sgl = &sport->tx_sgl[0];
+
+	if (!sport->dma_chan_tx)
+		return;
+
+	sport->tx_bytes = 0;
+	dmaengine_terminate_all(sport->dma_chan_tx);
+	if (sport->dma_is_txing) {
+		u32 ucr1;
+
+		dma_unmap_sg(sport->port.dev, sgl, sport->dma_tx_nents,
+			     DMA_TO_DEVICE);
+		ucr1 = imx_uart_readl(sport, UCR1);
+		ucr1 &= ~UCR1_TXDMAEN;
+		imx_uart_writel(sport, ucr1, UCR1);
+		sport->dma_is_txing = 0;
+	}
+
+	imx_uart_soft_reset(sport);
+
+}
+
+static void
+imx_uart_set_termios(struct uart_port *port, struct ktermios *termios,
+		     const struct ktermios *old)
+{
+	struct imx_port *sport = (struct imx_port *)port;
+	unsigned long flags;
+	u32 ucr2, old_ucr2, ufcr;
+	unsigned int baud, quot;
+	unsigned int old_csize = old ? old->c_cflag & CSIZE : CS8;
+	unsigned long div;
+	unsigned long num, denom, old_ubir, old_ubmr;
+	uint64_t tdiv64;
+
+	/*
+	 * We only support CS7 and CS8.
+	 */
+	while ((termios->c_cflag & CSIZE) != CS7 &&
+	       (termios->c_cflag & CSIZE) != CS8) {
+		termios->c_cflag &= ~CSIZE;
+		termios->c_cflag |= old_csize;
+		old_csize = CS8;
+	}
+
+	del_timer_sync(&sport->timer);
+
+	/*
+	 * Ask the core to calculate the divisor for us.
+	 */
+	baud = uart_get_baud_rate(port, termios, old, 50, port->uartclk / 16);
+	quot = uart_get_divisor(port, baud);
+
+	spin_lock_irqsave(&sport->port.lock, flags);
+
+	/*
+	 * Read current UCR2 and save it for future use, then clear all the bits
+	 * except those we will or may need to preserve.
+	 */
+	old_ucr2 = imx_uart_readl(sport, UCR2);
+	ucr2 = old_ucr2 & (UCR2_TXEN | UCR2_RXEN | UCR2_ATEN | UCR2_CTS);
+
+	ucr2 |= UCR2_SRST | UCR2_IRTS;
+	if ((termios->c_cflag & CSIZE) == CS8)
+		ucr2 |= UCR2_WS;
+
+	if (!sport->have_rtscts)
+		termios->c_cflag &= ~CRTSCTS;
+
+	if (port->rs485.flags & SER_RS485_ENABLED) {
+		/*
+		 * RTS is mandatory for rs485 operation, so keep
+		 * it under manual control and keep transmitter
+		 * disabled.
+		 */
+		if (port->rs485.flags & SER_RS485_RTS_AFTER_SEND)
+			imx_uart_rts_active(sport, &ucr2);
+		else
+			imx_uart_rts_inactive(sport, &ucr2);
+
+	} else if (termios->c_cflag & CRTSCTS) {
+		/*
+		 * Only let receiver control RTS output if we were not requested
+		 * to have RTS inactive (which then should take precedence).
+		 */
+		if (ucr2 & UCR2_CTS)
+			ucr2 |= UCR2_CTSC;
+	}
+
+	if (termios->c_cflag & CRTSCTS)
+		ucr2 &= ~UCR2_IRTS;
+	if (termios->c_cflag & CSTOPB)
+		ucr2 |= UCR2_STPB;
+	if (termios->c_cflag & PARENB) {
+		ucr2 |= UCR2_PREN;
+		if (termios->c_cflag & PARODD)
+			ucr2 |= UCR2_PROE;
+	}
+
+	sport->port.read_status_mask = 0;
+	if (termios->c_iflag & INPCK)
+		sport->port.read_status_mask |= (URXD_FRMERR | URXD_PRERR);
+	if (termios->c_iflag & (BRKINT | PARMRK))
+		sport->port.read_status_mask |= URXD_BRK;
+
+	/*
+	 * Characters to ignore
+	 */
+	sport->port.ignore_status_mask = 0;
+	if (termios->c_iflag & IGNPAR)
+		sport->port.ignore_status_mask |= URXD_PRERR | URXD_FRMERR;
+	if (termios->c_iflag & IGNBRK) {
+		sport->port.ignore_status_mask |= URXD_BRK;
+		/*
+		 * If we're ignoring parity and break indicators,
+		 * ignore overruns too (for real raw support).
+		 */
+		if (termios->c_iflag & IGNPAR)
+			sport->port.ignore_status_mask |= URXD_OVRRUN;
+	}
+
+	if ((termios->c_cflag & CREAD) == 0)
+		sport->port.ignore_status_mask |= URXD_DUMMY_READ;
+
+	/*
+	 * Update the per-port timeout.
+	 */
+	uart_update_timeout(port, termios->c_cflag, baud);
+
+	/* custom-baudrate handling */
+	div = sport->port.uartclk / (baud * 16);
+	if (baud == 38400 && quot != div)
+		baud = sport->port.uartclk / (quot * 16);
+
+	div = sport->port.uartclk / (baud * 16);
+	if (div > 7)
+		div = 7;
+	if (!div)
+		div = 1;
+
+	rational_best_approximation(16 * div * baud, sport->port.uartclk,
+		1 << 16, 1 << 16, &num, &denom);
+
+	tdiv64 = sport->port.uartclk;
+	tdiv64 *= num;
+	do_div(tdiv64, denom * 16 * div);
+	tty_termios_encode_baud_rate(termios,
+				(speed_t)tdiv64, (speed_t)tdiv64);
+
+	num -= 1;
+	denom -= 1;
+
+	ufcr = imx_uart_readl(sport, UFCR);
+	ufcr = (ufcr & (~UFCR_RFDIV)) | UFCR_RFDIV_REG(div);
+	imx_uart_writel(sport, ufcr, UFCR);
+
+	/*
+	 *  Two registers below should always be written both and in this
+	 *  particular order. One consequence is that we need to check if any of
+	 *  them changes and then update both. We do need the check for change
+	 *  as even writing the same values seem to "restart"
+	 *  transmission/receiving logic in the hardware, that leads to data
+	 *  breakage even when rate doesn't in fact change. E.g., user switches
+	 *  RTS/CTS handshake and suddenly gets broken bytes.
+	 */
+	old_ubir = imx_uart_readl(sport, UBIR);
+	old_ubmr = imx_uart_readl(sport, UBMR);
+	if (old_ubir != num || old_ubmr != denom) {
+		imx_uart_writel(sport, num, UBIR);
+		imx_uart_writel(sport, denom, UBMR);
+	}
+
+	if (!imx_uart_is_imx1(sport))
+		imx_uart_writel(sport, sport->port.uartclk / div / 1000,
+				IMX21_ONEMS);
+
+	imx_uart_writel(sport, ucr2, UCR2);
+
+	if (UART_ENABLE_MS(&sport->port, termios->c_cflag))
+		imx_uart_enable_ms(&sport->port);
+
+	spin_unlock_irqrestore(&sport->port.lock, flags);
+}
+
+static const char *imx_uart_type(struct uart_port *port)
+{
+	return port->type == PORT_IMX ? "IMX" : NULL;
+}
+
+/*
+ * Configure/autoconfigure the port.
+ */
+static void imx_uart_config_port(struct uart_port *port, int flags)
+{
+	if (flags & UART_CONFIG_TYPE)
+		port->type = PORT_IMX;
+}
+
+/*
+ * Verify the new serial_struct (for TIOCSSERIAL).
+ * The only change we allow are to the flags and type, and
+ * even then only between PORT_IMX and PORT_UNKNOWN
+ */
+static int
+imx_uart_verify_port(struct uart_port *port, struct serial_struct *ser)
+{
+	int ret = 0;
+
+	if (ser->type != PORT_UNKNOWN && ser->type != PORT_IMX)
+		ret = -EINVAL;
+	if (port->irq != ser->irq)
+		ret = -EINVAL;
+	if (ser->io_type != UPIO_MEM)
+		ret = -EINVAL;
+	if (port->uartclk / 16 != ser->baud_base)
+		ret = -EINVAL;
+	if (port->mapbase != (unsigned long)ser->iomem_base)
+		ret = -EINVAL;
+	if (port->iobase != ser->port)
+		ret = -EINVAL;
+	if (ser->hub6 != 0)
+		ret = -EINVAL;
+	return ret;
+}
+
+#if defined(CONFIG_CONSOLE_POLL)
+
+static int imx_uart_poll_init(struct uart_port *port)
+{
+	struct imx_port *sport = (struct imx_port *)port;
+	unsigned long flags;
+	u32 ucr1, ucr2;
+	int retval;
+
+	retval = clk_prepare_enable(sport->clk_ipg);
+	if (retval)
+		return retval;
+	retval = clk_prepare_enable(sport->clk_per);
+	if (retval)
+		clk_disable_unprepare(sport->clk_ipg);
+
+	imx_uart_setup_ufcr(sport, TXTL_DEFAULT, RXTL_DEFAULT);
+
+	spin_lock_irqsave(&sport->port.lock, flags);
+
+	/*
+	 * Be careful about the order of enabling bits here. First enable the
+	 * receiver (UARTEN + RXEN) and only then the corresponding irqs.
+	 * This prevents that a character that already sits in the RX fifo is
+	 * triggering an irq but the try to fetch it from there results in an
+	 * exception because UARTEN or RXEN is still off.
+	 */
+	ucr1 = imx_uart_readl(sport, UCR1);
+	ucr2 = imx_uart_readl(sport, UCR2);
+
+	if (imx_uart_is_imx1(sport))
+		ucr1 |= IMX1_UCR1_UARTCLKEN;
+
+	ucr1 |= UCR1_UARTEN;
+	ucr1 &= ~(UCR1_TRDYEN | UCR1_RTSDEN | UCR1_RRDYEN);
+
+	ucr2 |= UCR2_RXEN | UCR2_TXEN;
+	ucr2 &= ~UCR2_ATEN;
+
+	imx_uart_writel(sport, ucr1, UCR1);
+	imx_uart_writel(sport, ucr2, UCR2);
+
+	/* now enable irqs */
+	imx_uart_writel(sport, ucr1 | UCR1_RRDYEN, UCR1);
+	imx_uart_writel(sport, ucr2 | UCR2_ATEN, UCR2);
+
+	spin_unlock_irqrestore(&sport->port.lock, flags);
+
+	return 0;
+}
+
+static int imx_uart_poll_get_char(struct uart_port *port)
+{
+	struct imx_port *sport = (struct imx_port *)port;
+	if (!(imx_uart_readl(sport, USR2) & USR2_RDR))
+		return NO_POLL_CHAR;
+
+	return imx_uart_readl(sport, URXD0) & URXD_RX_DATA;
+}
+
+static void imx_uart_poll_put_char(struct uart_port *port, unsigned char c)
+{
+	struct imx_port *sport = (struct imx_port *)port;
+	unsigned int status;
+
+	/* drain */
+	do {
+		status = imx_uart_readl(sport, USR1);
+	} while (~status & USR1_TRDY);
+
+	/* write */
+	imx_uart_writel(sport, c, URTX0);
+
+	/* flush */
+	do {
+		status = imx_uart_readl(sport, USR2);
+	} while (~status & USR2_TXDC);
+}
+#endif
+
+/* called with port.lock taken and irqs off or from .probe without locking */
+static int imx_uart_rs485_config(struct uart_port *port, struct ktermios *termios,
+				 struct serial_rs485 *rs485conf)
+{
+	struct imx_port *sport = (struct imx_port *)port;
+	u32 ucr2;
+
+	if (rs485conf->flags & SER_RS485_ENABLED) {
+		/* Enable receiver if low-active RTS signal is requested */
+		if (sport->have_rtscts &&  !sport->have_rtsgpio &&
+		    !(rs485conf->flags & SER_RS485_RTS_ON_SEND))
+			rs485conf->flags |= SER_RS485_RX_DURING_TX;
+
+		/* disable transmitter */
+		ucr2 = imx_uart_readl(sport, UCR2);
+		if (rs485conf->flags & SER_RS485_RTS_AFTER_SEND)
+			imx_uart_rts_active(sport, &ucr2);
+		else
+			imx_uart_rts_inactive(sport, &ucr2);
+		imx_uart_writel(sport, ucr2, UCR2);
+	}
+
+	/* Make sure Rx is enabled in case Tx is active with Rx disabled */
+	if (!(rs485conf->flags & SER_RS485_ENABLED) ||
+	    rs485conf->flags & SER_RS485_RX_DURING_TX)
+		imx_uart_start_rx(port);
+
+	return 0;
+}
+
+static const struct uart_ops imx_uart_pops = {
+	.tx_empty	= imx_uart_tx_empty,
+	.set_mctrl	= imx_uart_set_mctrl,
+	.get_mctrl	= imx_uart_get_mctrl,
+	.stop_tx	= imx_uart_stop_tx,
+	.start_tx	= imx_uart_start_tx,
+	.stop_rx	= imx_uart_stop_rx,
+	.enable_ms	= imx_uart_enable_ms,
+	.break_ctl	= imx_uart_break_ctl,
+	.startup	= imx_uart_startup,
+	.shutdown	= imx_uart_shutdown,
+	.flush_buffer	= imx_uart_flush_buffer,
+	.set_termios	= imx_uart_set_termios,
+	.type		= imx_uart_type,
+	.config_port	= imx_uart_config_port,
+	.verify_port	= imx_uart_verify_port,
+#if defined(CONFIG_CONSOLE_POLL)
+	.poll_init      = imx_uart_poll_init,
+	.poll_get_char  = imx_uart_poll_get_char,
+	.poll_put_char  = imx_uart_poll_put_char,
+#endif
+};
+
+static struct imx_port *imx_uart_ports[UART_NR];
+
+#if IS_ENABLED(CONFIG_SERIAL_IMX_CONSOLE)
+static void imx_uart_console_putchar(struct uart_port *port, unsigned char ch)
+{
+	struct imx_port *sport = (struct imx_port *)port;
+
+	while (imx_uart_readl(sport, imx_uart_uts_reg(sport)) & UTS_TXFULL)
+		barrier();
+
+	imx_uart_writel(sport, ch, URTX0);
+}
+
+/*
+ * Interrupts are disabled on entering
+ */
+static void
+imx_uart_console_write(struct console *co, const char *s, unsigned int count)
+{
+	struct imx_port *sport = imx_uart_ports[co->index];
+	struct imx_port_ucrs old_ucr;
+	unsigned long flags;
+	unsigned int ucr1;
+	int locked = 1;
+
+	if (sport->port.sysrq)
+		locked = 0;
+	else if (oops_in_progress)
+		locked = spin_trylock_irqsave(&sport->port.lock, flags);
+	else
+		spin_lock_irqsave(&sport->port.lock, flags);
+
+	/*
+	 *	First, save UCR1/2/3 and then disable interrupts
+	 */
+	imx_uart_ucrs_save(sport, &old_ucr);
+	ucr1 = old_ucr.ucr1;
+
+	if (imx_uart_is_imx1(sport))
+		ucr1 |= IMX1_UCR1_UARTCLKEN;
+	ucr1 |= UCR1_UARTEN;
+	ucr1 &= ~(UCR1_TRDYEN | UCR1_RRDYEN | UCR1_RTSDEN);
+
+	imx_uart_writel(sport, ucr1, UCR1);
+
+	imx_uart_writel(sport, old_ucr.ucr2 | UCR2_TXEN, UCR2);
+
+	uart_console_write(&sport->port, s, count, imx_uart_console_putchar);
+
+	/*
+	 *	Finally, wait for transmitter to become empty
+	 *	and restore UCR1/2/3
+	 */
+	while (!(imx_uart_readl(sport, USR2) & USR2_TXDC));
+
+	imx_uart_ucrs_restore(sport, &old_ucr);
+
+	if (locked)
+		spin_unlock_irqrestore(&sport->port.lock, flags);
+}
+
+/*
+ * If the port was already initialised (eg, by a boot loader),
+ * try to determine the current setup.
+ */
+static void
+imx_uart_console_get_options(struct imx_port *sport, int *baud,
+			     int *parity, int *bits)
+{
+
+	if (imx_uart_readl(sport, UCR1) & UCR1_UARTEN) {
+		/* ok, the port was enabled */
+		unsigned int ucr2, ubir, ubmr, uartclk;
+		unsigned int baud_raw;
+		unsigned int ucfr_rfdiv;
+
+		ucr2 = imx_uart_readl(sport, UCR2);
+
+		*parity = 'n';
+		if (ucr2 & UCR2_PREN) {
+			if (ucr2 & UCR2_PROE)
+				*parity = 'o';
+			else
+				*parity = 'e';
+		}
+
+		if (ucr2 & UCR2_WS)
+			*bits = 8;
+		else
+			*bits = 7;
+
+		ubir = imx_uart_readl(sport, UBIR) & 0xffff;
+		ubmr = imx_uart_readl(sport, UBMR) & 0xffff;
+
+		ucfr_rfdiv = (imx_uart_readl(sport, UFCR) & UFCR_RFDIV) >> 7;
+		if (ucfr_rfdiv == 6)
+			ucfr_rfdiv = 7;
+		else
+			ucfr_rfdiv = 6 - ucfr_rfdiv;
+
+		uartclk = clk_get_rate(sport->clk_per);
+		uartclk /= ucfr_rfdiv;
+
+		{	/*
+			 * The next code provides exact computation of
+			 *   baud_raw = round(((uartclk/16) * (ubir + 1)) / (ubmr + 1))
+			 * without need of float support or long long division,
+			 * which would be required to prevent 32bit arithmetic overflow
+			 */
+			unsigned int mul = ubir + 1;
+			unsigned int div = 16 * (ubmr + 1);
+			unsigned int rem = uartclk % div;
+
+			baud_raw = (uartclk / div) * mul;
+			baud_raw += (rem * mul + div / 2) / div;
+			*baud = (baud_raw + 50) / 100 * 100;
+		}
+
+		if (*baud != baud_raw)
+			dev_info(sport->port.dev, "Console IMX rounded baud rate from %d to %d\n",
+				baud_raw, *baud);
+	}
+}
+
+static int
+imx_uart_console_setup(struct console *co, char *options)
+{
+	struct imx_port *sport;
+	int baud = 9600;
+	int bits = 8;
+	int parity = 'n';
+	int flow = 'n';
+	int retval;
+
+	/*
+	 * Check whether an invalid uart number has been specified, and
+	 * if so, search for the first available port that does have
+	 * console support.
+	 */
+	if (co->index == -1 || co->index >= ARRAY_SIZE(imx_uart_ports))
+		co->index = 0;
+	sport = imx_uart_ports[co->index];
+	if (sport == NULL)
+		return -ENODEV;
+
+	/* For setting the registers, we only need to enable the ipg clock. */
+	retval = clk_prepare_enable(sport->clk_ipg);
+	if (retval)
+		goto error_console;
+
+	if (options)
+		uart_parse_options(options, &baud, &parity, &bits, &flow);
+	else
+		imx_uart_console_get_options(sport, &baud, &parity, &bits);
+
+	imx_uart_setup_ufcr(sport, TXTL_DEFAULT, RXTL_DEFAULT);
+
+	retval = uart_set_options(&sport->port, co, baud, parity, bits, flow);
+
+	if (retval) {
+		clk_disable_unprepare(sport->clk_ipg);
+		goto error_console;
+	}
+
+	retval = clk_prepare_enable(sport->clk_per);
+	if (retval)
+		clk_disable_unprepare(sport->clk_ipg);
+
+error_console:
+	return retval;
+}
+
+static int
+imx_uart_console_exit(struct console *co)
+{
+	struct imx_port *sport = imx_uart_ports[co->index];
+
+	clk_disable_unprepare(sport->clk_per);
+	clk_disable_unprepare(sport->clk_ipg);
+
+	return 0;
+}
+
+static struct uart_driver imx_uart_uart_driver;
+static struct console imx_uart_console = {
+	.name		= DEV_NAME,
+	.write		= imx_uart_console_write,
+	.device		= uart_console_device,
+	.setup		= imx_uart_console_setup,
+	.exit		= imx_uart_console_exit,
+	.flags		= CON_PRINTBUFFER,
+	.index		= -1,
+	.data		= &imx_uart_uart_driver,
+};
+
+#define IMX_CONSOLE	&imx_uart_console
+
+#else
+#define IMX_CONSOLE	NULL
+#endif
+
+static struct uart_driver imx_uart_uart_driver = {
+	.owner          = THIS_MODULE,
+	.driver_name    = DRIVER_NAME,
+	.dev_name       = DEV_NAME,
+	.major          = SERIAL_IMX_MAJOR,
+	.minor          = MINOR_START,
+	.nr             = ARRAY_SIZE(imx_uart_ports),
+	.cons           = IMX_CONSOLE,
+};
+
+static enum hrtimer_restart imx_trigger_start_tx(struct hrtimer *t)
+{
+	struct imx_port *sport = container_of(t, struct imx_port, trigger_start_tx);
+	unsigned long flags;
+
+	spin_lock_irqsave(&sport->port.lock, flags);
+	if (sport->tx_state == WAIT_AFTER_RTS)
+		imx_uart_start_tx(&sport->port);
+	spin_unlock_irqrestore(&sport->port.lock, flags);
+
+	return HRTIMER_NORESTART;
+}
+
+static enum hrtimer_restart imx_trigger_stop_tx(struct hrtimer *t)
+{
+	struct imx_port *sport = container_of(t, struct imx_port, trigger_stop_tx);
+	unsigned long flags;
+
+	spin_lock_irqsave(&sport->port.lock, flags);
+	if (sport->tx_state == WAIT_AFTER_SEND)
+		imx_uart_stop_tx(&sport->port);
+	spin_unlock_irqrestore(&sport->port.lock, flags);
+
+	return HRTIMER_NORESTART;
+}
+
+static const struct serial_rs485 imx_rs485_supported = {
+	.flags = SER_RS485_ENABLED | SER_RS485_RTS_ON_SEND | SER_RS485_RTS_AFTER_SEND |
+		 SER_RS485_RX_DURING_TX,
+	.delay_rts_before_send = 1,
+	.delay_rts_after_send = 1,
+};
+
+/* Default RX DMA buffer configuration */
+#define RX_DMA_PERIODS		16
+#define RX_DMA_PERIOD_LEN	(PAGE_SIZE / 4)
+
+static int imx_uart_probe(struct platform_device *pdev)
+{
+	struct device_node *np = pdev->dev.of_node;
+	struct imx_port *sport;
+	void __iomem *base;
+	u32 dma_buf_conf[2];
+	int ret = 0;
+	u32 ucr1, ucr2, uts;
+	struct resource *res;
+	int txirq, rxirq, rtsirq;
+
+	sport = devm_kzalloc(&pdev->dev, sizeof(*sport), GFP_KERNEL);
+	if (!sport)
+		return -ENOMEM;
+
+	sport->devdata = of_device_get_match_data(&pdev->dev);
+
+	ret = of_alias_get_id(np, "serial");
+	if (ret < 0) {
+		dev_err(&pdev->dev, "failed to get alias id, errno %d\n", ret);
+		return ret;
+	}
+	sport->port.line = ret;
+
+	sport->have_rtscts = of_property_read_bool(np, "uart-has-rtscts") ||
+		of_property_read_bool(np, "fsl,uart-has-rtscts"); /* deprecated */
+
+	sport->dte_mode = of_property_read_bool(np, "fsl,dte-mode");
+
+	sport->have_rtsgpio = of_property_present(np, "rts-gpios");
+
+	sport->inverted_tx = of_property_read_bool(np, "fsl,inverted-tx");
+
+	sport->inverted_rx = of_property_read_bool(np, "fsl,inverted-rx");
+
+	if (!of_property_read_u32_array(np, "fsl,dma-info", dma_buf_conf, 2)) {
+		sport->rx_period_length = dma_buf_conf[0];
+		sport->rx_periods = dma_buf_conf[1];
+	} else {
+		sport->rx_period_length = RX_DMA_PERIOD_LEN;
+		sport->rx_periods = RX_DMA_PERIODS;
+	}
+
+	if (sport->port.line >= ARRAY_SIZE(imx_uart_ports)) {
+		dev_err(&pdev->dev, "serial%d out of range\n",
+			sport->port.line);
+		return -EINVAL;
+	}
+
+	base = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
+	if (IS_ERR(base))
+		return PTR_ERR(base);
+
+	rxirq = platform_get_irq(pdev, 0);
+	if (rxirq < 0)
+		return rxirq;
+	txirq = platform_get_irq_optional(pdev, 1);
+	rtsirq = platform_get_irq_optional(pdev, 2);
+
+	sport->port.dev = &pdev->dev;
+	sport->port.mapbase = res->start;
+	sport->port.membase = base;
+	sport->port.type = PORT_IMX;
+	sport->port.iotype = UPIO_MEM;
+	sport->port.irq = rxirq;
+	sport->port.fifosize = 32;
+	sport->port.has_sysrq = IS_ENABLED(CONFIG_SERIAL_IMX_CONSOLE);
+	sport->port.ops = &imx_uart_pops;
+	sport->port.rs485_config = imx_uart_rs485_config;
+	/* RTS is required to control the RS485 transmitter */
+	if (sport->have_rtscts || sport->have_rtsgpio)
+		sport->port.rs485_supported = imx_rs485_supported;
+	sport->port.flags = UPF_BOOT_AUTOCONF;
+	timer_setup(&sport->timer, imx_uart_timeout, 0);
+
+	sport->gpios = mctrl_gpio_init(&sport->port, 0);
+	if (IS_ERR(sport->gpios))
+		return PTR_ERR(sport->gpios);
+
+	sport->clk_ipg = devm_clk_get(&pdev->dev, "ipg");
+	if (IS_ERR(sport->clk_ipg)) {
+		ret = PTR_ERR(sport->clk_ipg);
+		dev_err(&pdev->dev, "failed to get ipg clk: %d\n", ret);
+		return ret;
+	}
+
+	sport->clk_per = devm_clk_get(&pdev->dev, "per");
+	if (IS_ERR(sport->clk_per)) {
+		ret = PTR_ERR(sport->clk_per);
+		dev_err(&pdev->dev, "failed to get per clk: %d\n", ret);
+		return ret;
+	}
+
+	sport->port.uartclk = clk_get_rate(sport->clk_per);
+
+	/* For register access, we only need to enable the ipg clock. */
+	ret = clk_prepare_enable(sport->clk_ipg);
+	if (ret) {
+		dev_err(&pdev->dev, "failed to enable ipg clk: %d\n", ret);
+		return ret;
+	}
+
+	ret = uart_get_rs485_mode(&sport->port);
+	if (ret)
+		goto err_clk;
+
+	/*
+	 * If using the i.MX UART RTS/CTS control then the RTS (CTS_B)
+	 * signal cannot be set low during transmission in case the
+	 * receiver is off (limitation of the i.MX UART IP).
+	 */
+	if (sport->port.rs485.flags & SER_RS485_ENABLED &&
+	    sport->have_rtscts && !sport->have_rtsgpio &&
+	    (!(sport->port.rs485.flags & SER_RS485_RTS_ON_SEND) &&
+	     !(sport->port.rs485.flags & SER_RS485_RX_DURING_TX)))
+		dev_err(&pdev->dev,
+			"low-active RTS not possible when receiver is off, enabling receiver\n");
+
+	/* Disable interrupts before requesting them */
+	ucr1 = imx_uart_readl(sport, UCR1);
+	ucr1 &= ~(UCR1_ADEN | UCR1_TRDYEN | UCR1_IDEN | UCR1_RRDYEN | UCR1_RTSDEN);
+	imx_uart_writel(sport, ucr1, UCR1);
+
+	/* Disable Ageing Timer interrupt */
+	ucr2 = imx_uart_readl(sport, UCR2);
+	ucr2 &= ~UCR2_ATEN;
+	imx_uart_writel(sport, ucr2, UCR2);
+
+	/*
+	 * In case RS485 is enabled without GPIO RTS control, the UART IP
+	 * is used to control CTS signal. Keep both the UART and Receiver
+	 * enabled, otherwise the UART IP pulls CTS signal always HIGH no
+	 * matter how the UCR2 CTSC and CTS bits are set. To prevent any
+	 * data from being fed into the RX FIFO, enable loopback mode in
+	 * UTS register, which disconnects the RX path from external RXD
+	 * pin and connects it to the Transceiver, which is disabled, so
+	 * no data can be fed to the RX FIFO that way.
+	 */
+	if (sport->port.rs485.flags & SER_RS485_ENABLED &&
+	    sport->have_rtscts && !sport->have_rtsgpio) {
+		uts = imx_uart_readl(sport, imx_uart_uts_reg(sport));
+		uts |= UTS_LOOP;
+		imx_uart_writel(sport, uts, imx_uart_uts_reg(sport));
+
+		ucr1 = imx_uart_readl(sport, UCR1);
+		ucr1 |= UCR1_UARTEN;
+		imx_uart_writel(sport, ucr1, UCR1);
+
+		ucr2 = imx_uart_readl(sport, UCR2);
+		ucr2 |= UCR2_RXEN;
+		imx_uart_writel(sport, ucr2, UCR2);
+	}
+
+	if (!imx_uart_is_imx1(sport) && sport->dte_mode) {
+		/*
+		 * The DCEDTE bit changes the direction of DSR, DCD, DTR and RI
+		 * and influences if UCR3_RI and UCR3_DCD changes the level of RI
+		 * and DCD (when they are outputs) or enables the respective
+		 * irqs. So set this bit early, i.e. before requesting irqs.
+		 */
+		u32 ufcr = imx_uart_readl(sport, UFCR);
+		if (!(ufcr & UFCR_DCEDTE))
+			imx_uart_writel(sport, ufcr | UFCR_DCEDTE, UFCR);
+
+		/*
+		 * Disable UCR3_RI and UCR3_DCD irqs. They are also not
+		 * enabled later because they cannot be cleared
+		 * (confirmed on i.MX25) which makes them unusable.
+		 */
+		imx_uart_writel(sport,
+				IMX21_UCR3_RXDMUXSEL | UCR3_ADNIMP | UCR3_DSR,
+				UCR3);
+
+	} else {
+		u32 ucr3 = UCR3_DSR;
+		u32 ufcr = imx_uart_readl(sport, UFCR);
+		if (ufcr & UFCR_DCEDTE)
+			imx_uart_writel(sport, ufcr & ~UFCR_DCEDTE, UFCR);
+
+		if (!imx_uart_is_imx1(sport))
+			ucr3 |= IMX21_UCR3_RXDMUXSEL | UCR3_ADNIMP;
+		imx_uart_writel(sport, ucr3, UCR3);
+	}
+
+	hrtimer_init(&sport->trigger_start_tx, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+	hrtimer_init(&sport->trigger_stop_tx, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+	sport->trigger_start_tx.function = imx_trigger_start_tx;
+	sport->trigger_stop_tx.function = imx_trigger_stop_tx;
+
+	/*
+	 * Allocate the IRQ(s) i.MX1 has three interrupts whereas later
+	 * chips only have one interrupt.
+	 */
+	if (txirq > 0) {
+		ret = devm_request_irq(&pdev->dev, rxirq, imx_uart_rxint, 0,
+				       dev_name(&pdev->dev), sport);
+		if (ret) {
+			dev_err(&pdev->dev, "failed to request rx irq: %d\n",
+				ret);
+			goto err_clk;
+		}
+
+		ret = devm_request_irq(&pdev->dev, txirq, imx_uart_txint, 0,
+				       dev_name(&pdev->dev), sport);
+		if (ret) {
+			dev_err(&pdev->dev, "failed to request tx irq: %d\n",
+				ret);
+			goto err_clk;
+		}
+
+		ret = devm_request_irq(&pdev->dev, rtsirq, imx_uart_rtsint, 0,
+				       dev_name(&pdev->dev), sport);
+		if (ret) {
+			dev_err(&pdev->dev, "failed to request rts irq: %d\n",
+				ret);
+			goto err_clk;
+		}
+	} else {
+		ret = devm_request_irq(&pdev->dev, rxirq, imx_uart_int, 0,
+				       dev_name(&pdev->dev), sport);
+		if (ret) {
+			dev_err(&pdev->dev, "failed to request irq: %d\n", ret);
+			goto err_clk;
+		}
+	}
+
+	imx_uart_ports[sport->port.line] = sport;
+
+	platform_set_drvdata(pdev, sport);
+
+	ret = uart_add_one_port(&imx_uart_uart_driver, &sport->port);
+
+err_clk:
+	clk_disable_unprepare(sport->clk_ipg);
+
+	return ret;
+}
+
+static int imx_uart_remove(struct platform_device *pdev)
+{
+	struct imx_port *sport = platform_get_drvdata(pdev);
+
+	uart_remove_one_port(&imx_uart_uart_driver, &sport->port);
+
+	return 0;
+}
+
+static void imx_uart_restore_context(struct imx_port *sport)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&sport->port.lock, flags);
+	if (!sport->context_saved) {
+		spin_unlock_irqrestore(&sport->port.lock, flags);
+		return;
+	}
+
+	imx_uart_writel(sport, sport->saved_reg[4], UFCR);
+	imx_uart_writel(sport, sport->saved_reg[5], UESC);
+	imx_uart_writel(sport, sport->saved_reg[6], UTIM);
+	imx_uart_writel(sport, sport->saved_reg[7], UBIR);
+	imx_uart_writel(sport, sport->saved_reg[8], UBMR);
+	imx_uart_writel(sport, sport->saved_reg[9], IMX21_UTS);
+	imx_uart_writel(sport, sport->saved_reg[0], UCR1);
+	imx_uart_writel(sport, sport->saved_reg[1] | UCR2_SRST, UCR2);
+	imx_uart_writel(sport, sport->saved_reg[2], UCR3);
+	imx_uart_writel(sport, sport->saved_reg[3], UCR4);
+	sport->context_saved = false;
+	spin_unlock_irqrestore(&sport->port.lock, flags);
+}
+
+static void imx_uart_save_context(struct imx_port *sport)
+{
+	unsigned long flags;
+
+	/* Save necessary regs */
+	spin_lock_irqsave(&sport->port.lock, flags);
+	sport->saved_reg[0] = imx_uart_readl(sport, UCR1);
+	sport->saved_reg[1] = imx_uart_readl(sport, UCR2);
+	sport->saved_reg[2] = imx_uart_readl(sport, UCR3);
+	sport->saved_reg[3] = imx_uart_readl(sport, UCR4);
+	sport->saved_reg[4] = imx_uart_readl(sport, UFCR);
+	sport->saved_reg[5] = imx_uart_readl(sport, UESC);
+	sport->saved_reg[6] = imx_uart_readl(sport, UTIM);
+	sport->saved_reg[7] = imx_uart_readl(sport, UBIR);
+	sport->saved_reg[8] = imx_uart_readl(sport, UBMR);
+	sport->saved_reg[9] = imx_uart_readl(sport, IMX21_UTS);
+	sport->context_saved = true;
+	spin_unlock_irqrestore(&sport->port.lock, flags);
+}
+
+static void imx_uart_enable_wakeup(struct imx_port *sport, bool on)
+{
+	u32 ucr3;
+
+	ucr3 = imx_uart_readl(sport, UCR3);
+	if (on) {
+		imx_uart_writel(sport, USR1_AWAKE, USR1);
+		ucr3 |= UCR3_AWAKEN;
+	} else {
+		ucr3 &= ~UCR3_AWAKEN;
+	}
+	imx_uart_writel(sport, ucr3, UCR3);
+
+	if (sport->have_rtscts) {
+		u32 ucr1 = imx_uart_readl(sport, UCR1);
+		if (on) {
+			imx_uart_writel(sport, USR1_RTSD, USR1);
+			ucr1 |= UCR1_RTSDEN;
+		} else {
+			ucr1 &= ~UCR1_RTSDEN;
+		}
+		imx_uart_writel(sport, ucr1, UCR1);
+	}
+}
+
+static int imx_uart_suspend_noirq(struct device *dev)
+{
+	struct imx_port *sport = dev_get_drvdata(dev);
+
+	imx_uart_save_context(sport);
+
+	clk_disable(sport->clk_ipg);
+
+	pinctrl_pm_select_sleep_state(dev);
+
+	return 0;
+}
+
+static int imx_uart_resume_noirq(struct device *dev)
+{
+	struct imx_port *sport = dev_get_drvdata(dev);
+	int ret;
+
+	pinctrl_pm_select_default_state(dev);
+
+	ret = clk_enable(sport->clk_ipg);
+	if (ret)
+		return ret;
+
+	imx_uart_restore_context(sport);
+
+	return 0;
+}
+
+static int imx_uart_suspend(struct device *dev)
+{
+	struct imx_port *sport = dev_get_drvdata(dev);
+	int ret;
+
+	uart_suspend_port(&imx_uart_uart_driver, &sport->port);
+	disable_irq(sport->port.irq);
+
+	ret = clk_prepare_enable(sport->clk_ipg);
+	if (ret)
+		return ret;
+
+	/* enable wakeup from i.MX UART */
+	imx_uart_enable_wakeup(sport, true);
+
+	return 0;
+}
+
+static int imx_uart_resume(struct device *dev)
+{
+	struct imx_port *sport = dev_get_drvdata(dev);
+
+	/* disable wakeup from i.MX UART */
+	imx_uart_enable_wakeup(sport, false);
+
+	uart_resume_port(&imx_uart_uart_driver, &sport->port);
+	enable_irq(sport->port.irq);
+
+	clk_disable_unprepare(sport->clk_ipg);
+
+	return 0;
+}
+
+static int imx_uart_freeze(struct device *dev)
+{
+	struct imx_port *sport = dev_get_drvdata(dev);
+
+	uart_suspend_port(&imx_uart_uart_driver, &sport->port);
+
+	return clk_prepare_enable(sport->clk_ipg);
+}
+
+static int imx_uart_thaw(struct device *dev)
+{
+	struct imx_port *sport = dev_get_drvdata(dev);
+
+	uart_resume_port(&imx_uart_uart_driver, &sport->port);
+
+	clk_disable_unprepare(sport->clk_ipg);
+
+	return 0;
+}
+
+static const struct dev_pm_ops imx_uart_pm_ops = {
+	.suspend_noirq = imx_uart_suspend_noirq,
+	.resume_noirq = imx_uart_resume_noirq,
+	.freeze_noirq = imx_uart_suspend_noirq,
+	.thaw_noirq = imx_uart_resume_noirq,
+	.restore_noirq = imx_uart_resume_noirq,
+	.suspend = imx_uart_suspend,
+	.resume = imx_uart_resume,
+	.freeze = imx_uart_freeze,
+	.thaw = imx_uart_thaw,
+	.restore = imx_uart_thaw,
+};
+
+static struct platform_driver imx_uart_platform_driver = {
+	.probe = imx_uart_probe,
+	.remove = imx_uart_remove,
+
+	.driver = {
+		.name = "imx-uart",
+		.of_match_table = imx_uart_dt_ids,
+		.pm = &imx_uart_pm_ops,
+	},
+};
+
+static int __init imx_uart_init(void)
+{
+	int ret = uart_register_driver(&imx_uart_uart_driver);
+
+	if (ret)
+		return ret;
+
+	ret = platform_driver_register(&imx_uart_platform_driver);
+	if (ret != 0)
+		uart_unregister_driver(&imx_uart_uart_driver);
+
+	return ret;
+}
+
+static void __exit imx_uart_exit(void)
+{
+	platform_driver_unregister(&imx_uart_platform_driver);
+	uart_unregister_driver(&imx_uart_uart_driver);
+}
+
+module_init(imx_uart_init);
+module_exit(imx_uart_exit);
+
+MODULE_AUTHOR("Sascha Hauer");
+MODULE_DESCRIPTION("IMX generic serial port driver");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:imx-uart");