Adding upstream version 6.1.76.upstream/6.1.76

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

1 files changed, 2113 insertions, 0 deletions

diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c
new file mode 100644
index 000000000..2a9c40588
--- /dev/null
+++ b/drivers/tty/serial/stm32-usart.c
@@ -0,0 +1,2113 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) Maxime Coquelin 2015
+ * Copyright (C) STMicroelectronics SA 2017
+ * Authors:  Maxime Coquelin <mcoquelin.stm32@gmail.com>
+ *	     Gerald Baeza <gerald.baeza@foss.st.com>
+ *	     Erwan Le Ray <erwan.leray@foss.st.com>
+ *
+ * Inspired by st-asc.c from STMicroelectronics (c)
+ */
+
+#include <linux/clk.h>
+#include <linux/console.h>
+#include <linux/delay.h>
+#include <linux/dma-direction.h>
+#include <linux/dmaengine.h>
+#include <linux/dma-mapping.h>
+#include <linux/io.h>
+#include <linux/iopoll.h>
+#include <linux/irq.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
+#include <linux/pinctrl/consumer.h>
+#include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
+#include <linux/pm_wakeirq.h>
+#include <linux/serial_core.h>
+#include <linux/serial.h>
+#include <linux/spinlock.h>
+#include <linux/sysrq.h>
+#include <linux/tty_flip.h>
+#include <linux/tty.h>
+
+#include "serial_mctrl_gpio.h"
+#include "stm32-usart.h"
+
+
+/* Register offsets */
+static struct stm32_usart_info __maybe_unused stm32f4_info = {
+	.ofs = {
+		.isr	= 0x00,
+		.rdr	= 0x04,
+		.tdr	= 0x04,
+		.brr	= 0x08,
+		.cr1	= 0x0c,
+		.cr2	= 0x10,
+		.cr3	= 0x14,
+		.gtpr	= 0x18,
+		.rtor	= UNDEF_REG,
+		.rqr	= UNDEF_REG,
+		.icr	= UNDEF_REG,
+	},
+	.cfg = {
+		.uart_enable_bit = 13,
+		.has_7bits_data = false,
+		.fifosize = 1,
+	}
+};
+
+static struct stm32_usart_info __maybe_unused stm32f7_info = {
+	.ofs = {
+		.cr1	= 0x00,
+		.cr2	= 0x04,
+		.cr3	= 0x08,
+		.brr	= 0x0c,
+		.gtpr	= 0x10,
+		.rtor	= 0x14,
+		.rqr	= 0x18,
+		.isr	= 0x1c,
+		.icr	= 0x20,
+		.rdr	= 0x24,
+		.tdr	= 0x28,
+	},
+	.cfg = {
+		.uart_enable_bit = 0,
+		.has_7bits_data = true,
+		.has_swap = true,
+		.fifosize = 1,
+	}
+};
+
+static struct stm32_usart_info __maybe_unused stm32h7_info = {
+	.ofs = {
+		.cr1	= 0x00,
+		.cr2	= 0x04,
+		.cr3	= 0x08,
+		.brr	= 0x0c,
+		.gtpr	= 0x10,
+		.rtor	= 0x14,
+		.rqr	= 0x18,
+		.isr	= 0x1c,
+		.icr	= 0x20,
+		.rdr	= 0x24,
+		.tdr	= 0x28,
+	},
+	.cfg = {
+		.uart_enable_bit = 0,
+		.has_7bits_data = true,
+		.has_swap = true,
+		.has_wakeup = true,
+		.has_fifo = true,
+		.fifosize = 16,
+	}
+};
+
+static void stm32_usart_stop_tx(struct uart_port *port);
+static void stm32_usart_transmit_chars(struct uart_port *port);
+static void __maybe_unused stm32_usart_console_putchar(struct uart_port *port, unsigned char ch);
+
+static inline struct stm32_port *to_stm32_port(struct uart_port *port)
+{
+	return container_of(port, struct stm32_port, port);
+}
+
+static void stm32_usart_set_bits(struct uart_port *port, u32 reg, u32 bits)
+{
+	u32 val;
+
+	val = readl_relaxed(port->membase + reg);
+	val |= bits;
+	writel_relaxed(val, port->membase + reg);
+}
+
+static void stm32_usart_clr_bits(struct uart_port *port, u32 reg, u32 bits)
+{
+	u32 val;
+
+	val = readl_relaxed(port->membase + reg);
+	val &= ~bits;
+	writel_relaxed(val, port->membase + reg);
+}
+
+static unsigned int stm32_usart_tx_empty(struct uart_port *port)
+{
+	struct stm32_port *stm32_port = to_stm32_port(port);
+	const struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
+
+	if (readl_relaxed(port->membase + ofs->isr) & USART_SR_TC)
+		return TIOCSER_TEMT;
+
+	return 0;
+}
+
+static void stm32_usart_rs485_rts_enable(struct uart_port *port)
+{
+	struct stm32_port *stm32_port = to_stm32_port(port);
+	struct serial_rs485 *rs485conf = &port->rs485;
+
+	if (stm32_port->hw_flow_control ||
+	    !(rs485conf->flags & SER_RS485_ENABLED))
+		return;
+
+	if (rs485conf->flags & SER_RS485_RTS_ON_SEND) {
+		mctrl_gpio_set(stm32_port->gpios,
+			       stm32_port->port.mctrl | TIOCM_RTS);
+	} else {
+		mctrl_gpio_set(stm32_port->gpios,
+			       stm32_port->port.mctrl & ~TIOCM_RTS);
+	}
+}
+
+static void stm32_usart_rs485_rts_disable(struct uart_port *port)
+{
+	struct stm32_port *stm32_port = to_stm32_port(port);
+	struct serial_rs485 *rs485conf = &port->rs485;
+
+	if (stm32_port->hw_flow_control ||
+	    !(rs485conf->flags & SER_RS485_ENABLED))
+		return;
+
+	if (rs485conf->flags & SER_RS485_RTS_ON_SEND) {
+		mctrl_gpio_set(stm32_port->gpios,
+			       stm32_port->port.mctrl & ~TIOCM_RTS);
+	} else {
+		mctrl_gpio_set(stm32_port->gpios,
+			       stm32_port->port.mctrl | TIOCM_RTS);
+	}
+}
+
+static void stm32_usart_config_reg_rs485(u32 *cr1, u32 *cr3, u32 delay_ADE,
+					 u32 delay_DDE, u32 baud)
+{
+	u32 rs485_deat_dedt;
+	u32 rs485_deat_dedt_max = (USART_CR1_DEAT_MASK >> USART_CR1_DEAT_SHIFT);
+	bool over8;
+
+	*cr3 |= USART_CR3_DEM;
+	over8 = *cr1 & USART_CR1_OVER8;
+
+	*cr1 &= ~(USART_CR1_DEDT_MASK | USART_CR1_DEAT_MASK);
+
+	if (over8)
+		rs485_deat_dedt = delay_ADE * baud * 8;
+	else
+		rs485_deat_dedt = delay_ADE * baud * 16;
+
+	rs485_deat_dedt = DIV_ROUND_CLOSEST(rs485_deat_dedt, 1000);
+	rs485_deat_dedt = rs485_deat_dedt > rs485_deat_dedt_max ?
+			  rs485_deat_dedt_max : rs485_deat_dedt;
+	rs485_deat_dedt = (rs485_deat_dedt << USART_CR1_DEAT_SHIFT) &
+			   USART_CR1_DEAT_MASK;
+	*cr1 |= rs485_deat_dedt;
+
+	if (over8)
+		rs485_deat_dedt = delay_DDE * baud * 8;
+	else
+		rs485_deat_dedt = delay_DDE * baud * 16;
+
+	rs485_deat_dedt = DIV_ROUND_CLOSEST(rs485_deat_dedt, 1000);
+	rs485_deat_dedt = rs485_deat_dedt > rs485_deat_dedt_max ?
+			  rs485_deat_dedt_max : rs485_deat_dedt;
+	rs485_deat_dedt = (rs485_deat_dedt << USART_CR1_DEDT_SHIFT) &
+			   USART_CR1_DEDT_MASK;
+	*cr1 |= rs485_deat_dedt;
+}
+
+static int stm32_usart_config_rs485(struct uart_port *port, struct ktermios *termios,
+				    struct serial_rs485 *rs485conf)
+{
+	struct stm32_port *stm32_port = to_stm32_port(port);
+	const struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
+	const struct stm32_usart_config *cfg = &stm32_port->info->cfg;
+	u32 usartdiv, baud, cr1, cr3;
+	bool over8;
+
+	stm32_usart_clr_bits(port, ofs->cr1, BIT(cfg->uart_enable_bit));
+
+	rs485conf->flags |= SER_RS485_RX_DURING_TX;
+
+	if (rs485conf->flags & SER_RS485_ENABLED) {
+		cr1 = readl_relaxed(port->membase + ofs->cr1);
+		cr3 = readl_relaxed(port->membase + ofs->cr3);
+		usartdiv = readl_relaxed(port->membase + ofs->brr);
+		usartdiv = usartdiv & GENMASK(15, 0);
+		over8 = cr1 & USART_CR1_OVER8;
+
+		if (over8)
+			usartdiv = usartdiv | (usartdiv & GENMASK(4, 0))
+				   << USART_BRR_04_R_SHIFT;
+
+		baud = DIV_ROUND_CLOSEST(port->uartclk, usartdiv);
+		stm32_usart_config_reg_rs485(&cr1, &cr3,
+					     rs485conf->delay_rts_before_send,
+					     rs485conf->delay_rts_after_send,
+					     baud);
+
+		if (rs485conf->flags & SER_RS485_RTS_ON_SEND)
+			cr3 &= ~USART_CR3_DEP;
+		else
+			cr3 |= USART_CR3_DEP;
+
+		writel_relaxed(cr3, port->membase + ofs->cr3);
+		writel_relaxed(cr1, port->membase + ofs->cr1);
+	} else {
+		stm32_usart_clr_bits(port, ofs->cr3,
+				     USART_CR3_DEM | USART_CR3_DEP);
+		stm32_usart_clr_bits(port, ofs->cr1,
+				     USART_CR1_DEDT_MASK | USART_CR1_DEAT_MASK);
+	}
+
+	stm32_usart_set_bits(port, ofs->cr1, BIT(cfg->uart_enable_bit));
+
+	/* Adjust RTS polarity in case it's driven in software */
+	if (stm32_usart_tx_empty(port))
+		stm32_usart_rs485_rts_disable(port);
+	else
+		stm32_usart_rs485_rts_enable(port);
+
+	return 0;
+}
+
+static int stm32_usart_init_rs485(struct uart_port *port,
+				  struct platform_device *pdev)
+{
+	struct serial_rs485 *rs485conf = &port->rs485;
+
+	rs485conf->flags = 0;
+	rs485conf->delay_rts_before_send = 0;
+	rs485conf->delay_rts_after_send = 0;
+
+	if (!pdev->dev.of_node)
+		return -ENODEV;
+
+	return uart_get_rs485_mode(port);
+}
+
+static bool stm32_usart_rx_dma_enabled(struct uart_port *port)
+{
+	struct stm32_port *stm32_port = to_stm32_port(port);
+	const struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
+
+	if (!stm32_port->rx_ch)
+		return false;
+
+	return !!(readl_relaxed(port->membase + ofs->cr3) & USART_CR3_DMAR);
+}
+
+/* Return true when data is pending (in pio mode), and false when no data is pending. */
+static bool stm32_usart_pending_rx_pio(struct uart_port *port, u32 *sr)
+{
+	struct stm32_port *stm32_port = to_stm32_port(port);
+	const struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
+
+	*sr = readl_relaxed(port->membase + ofs->isr);
+	/* Get pending characters in RDR or FIFO */
+	if (*sr & USART_SR_RXNE) {
+		/* Get all pending characters from the RDR or the FIFO when using interrupts */
+		if (!stm32_usart_rx_dma_enabled(port))
+			return true;
+
+		/* Handle only RX data errors when using DMA */
+		if (*sr & USART_SR_ERR_MASK)
+			return true;
+	}
+
+	return false;
+}
+
+static unsigned long stm32_usart_get_char_pio(struct uart_port *port)
+{
+	struct stm32_port *stm32_port = to_stm32_port(port);
+	const struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
+	unsigned long c;
+
+	c = readl_relaxed(port->membase + ofs->rdr);
+	/* Apply RDR data mask */
+	c &= stm32_port->rdr_mask;
+
+	return c;
+}
+
+static unsigned int stm32_usart_receive_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;
+	unsigned long c;
+	unsigned int size = 0;
+	u32 sr;
+	char flag;
+
+	while (stm32_usart_pending_rx_pio(port, &sr)) {
+		sr |= USART_SR_DUMMY_RX;
+		flag = TTY_NORMAL;
+
+		/*
+		 * Status bits has to be cleared before reading the RDR:
+		 * In FIFO mode, reading the RDR will pop the next data
+		 * (if any) along with its status bits into the SR.
+		 * Not doing so leads to misalignement between RDR and SR,
+		 * and clear status bits of the next rx data.
+		 *
+		 * Clear errors flags for stm32f7 and stm32h7 compatible
+		 * devices. On stm32f4 compatible devices, the error bit is
+		 * cleared by the sequence [read SR - read DR].
+		 */
+		if ((sr & USART_SR_ERR_MASK) && ofs->icr != UNDEF_REG)
+			writel_relaxed(sr & USART_SR_ERR_MASK,
+				       port->membase + ofs->icr);
+
+		c = stm32_usart_get_char_pio(port);
+		port->icount.rx++;
+		size++;
+		if (sr & USART_SR_ERR_MASK) {
+			if (sr & USART_SR_ORE) {
+				port->icount.overrun++;
+			} else if (sr & USART_SR_PE) {
+				port->icount.parity++;
+			} else if (sr & USART_SR_FE) {
+				/* Break detection if character is null */
+				if (!c) {
+					port->icount.brk++;
+					if (uart_handle_break(port))
+						continue;
+				} else {
+					port->icount.frame++;
+				}
+			}
+
+			sr &= port->read_status_mask;
+
+			if (sr & USART_SR_PE) {
+				flag = TTY_PARITY;
+			} else if (sr & USART_SR_FE) {
+				if (!c)
+					flag = TTY_BREAK;
+				else
+					flag = TTY_FRAME;
+			}
+		}
+
+		if (uart_prepare_sysrq_char(port, c))
+			continue;
+		uart_insert_char(port, sr, USART_SR_ORE, c, flag);
+	}
+
+	return size;
+}
+
+static void stm32_usart_push_buffer_dma(struct uart_port *port, unsigned int dma_size)
+{
+	struct stm32_port *stm32_port = to_stm32_port(port);
+	struct tty_port *ttyport = &stm32_port->port.state->port;
+	unsigned char *dma_start;
+	int dma_count, i;
+
+	dma_start = stm32_port->rx_buf + (RX_BUF_L - stm32_port->last_res);
+
+	/*
+	 * Apply rdr_mask on buffer in order to mask parity bit.
+	 * This loop is useless in cs8 mode because DMA copies only
+	 * 8 bits and already ignores parity bit.
+	 */
+	if (!(stm32_port->rdr_mask == (BIT(8) - 1)))
+		for (i = 0; i < dma_size; i++)
+			*(dma_start + i) &= stm32_port->rdr_mask;
+
+	dma_count = tty_insert_flip_string(ttyport, dma_start, dma_size);
+	port->icount.rx += dma_count;
+	if (dma_count != dma_size)
+		port->icount.buf_overrun++;
+	stm32_port->last_res -= dma_count;
+	if (stm32_port->last_res == 0)
+		stm32_port->last_res = RX_BUF_L;
+}
+
+static unsigned int stm32_usart_receive_chars_dma(struct uart_port *port)
+{
+	struct stm32_port *stm32_port = to_stm32_port(port);
+	unsigned int dma_size, size = 0;
+
+	/* DMA buffer is configured in cyclic mode and handles the rollback of the buffer. */
+	if (stm32_port->rx_dma_state.residue > stm32_port->last_res) {
+		/* Conditional first part: from last_res to end of DMA buffer */
+		dma_size = stm32_port->last_res;
+		stm32_usart_push_buffer_dma(port, dma_size);
+		size = dma_size;
+	}
+
+	dma_size = stm32_port->last_res - stm32_port->rx_dma_state.residue;
+	stm32_usart_push_buffer_dma(port, dma_size);
+	size += dma_size;
+
+	return size;
+}
+
+static unsigned int stm32_usart_receive_chars(struct uart_port *port, bool force_dma_flush)
+{
+	struct stm32_port *stm32_port = to_stm32_port(port);
+	const struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
+	enum dma_status rx_dma_status;
+	u32 sr;
+	unsigned int size = 0;
+
+	if (stm32_usart_rx_dma_enabled(port) || force_dma_flush) {
+		rx_dma_status = dmaengine_tx_status(stm32_port->rx_ch,
+						    stm32_port->rx_ch->cookie,
+						    &stm32_port->rx_dma_state);
+		if (rx_dma_status == DMA_IN_PROGRESS) {
+			/* Empty DMA buffer */
+			size = stm32_usart_receive_chars_dma(port);
+			sr = readl_relaxed(port->membase + ofs->isr);
+			if (sr & USART_SR_ERR_MASK) {
+				/* Disable DMA request line */
+				stm32_usart_clr_bits(port, ofs->cr3, USART_CR3_DMAR);
+
+				/* Switch to PIO mode to handle the errors */
+				size += stm32_usart_receive_chars_pio(port);
+
+				/* Switch back to DMA mode */
+				stm32_usart_set_bits(port, ofs->cr3, USART_CR3_DMAR);
+			}
+		} else {
+			/* Disable RX DMA */
+			dmaengine_terminate_async(stm32_port->rx_ch);
+			stm32_usart_clr_bits(port, ofs->cr3, USART_CR3_DMAR);
+			/* Fall back to interrupt mode */
+			dev_dbg(port->dev, "DMA error, fallback to irq mode\n");
+			size = stm32_usart_receive_chars_pio(port);
+		}
+	} else {
+		size = stm32_usart_receive_chars_pio(port);
+	}
+
+	return size;
+}
+
+static void stm32_usart_tx_dma_terminate(struct stm32_port *stm32_port)
+{
+	dmaengine_terminate_async(stm32_port->tx_ch);
+	stm32_port->tx_dma_busy = false;
+}
+
+static bool stm32_usart_tx_dma_started(struct stm32_port *stm32_port)
+{
+	/*
+	 * We cannot use the function "dmaengine_tx_status" to know the
+	 * status of DMA. This function does not show if the "dma complete"
+	 * callback of the DMA transaction has been called. So we prefer
+	 * to use "tx_dma_busy" flag to prevent dual DMA transaction at the
+	 * same time.
+	 */
+	return stm32_port->tx_dma_busy;
+}
+
+static bool stm32_usart_tx_dma_enabled(struct stm32_port *stm32_port)
+{
+	const struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
+
+	return !!(readl_relaxed(stm32_port->port.membase + ofs->cr3) & USART_CR3_DMAT);
+}
+
+static void stm32_usart_tx_dma_complete(void *arg)
+{
+	struct uart_port *port = arg;
+	struct stm32_port *stm32port = to_stm32_port(port);
+	const struct stm32_usart_offsets *ofs = &stm32port->info->ofs;
+	unsigned long flags;
+
+	stm32_usart_clr_bits(port, ofs->cr3, USART_CR3_DMAT);
+	stm32_usart_tx_dma_terminate(stm32port);
+
+	/* Let's see if we have pending data to send */
+	spin_lock_irqsave(&port->lock, flags);
+	stm32_usart_transmit_chars(port);
+	spin_unlock_irqrestore(&port->lock, flags);
+}
+
+static void stm32_usart_tx_interrupt_enable(struct uart_port *port)
+{
+	struct stm32_port *stm32_port = to_stm32_port(port);
+	const struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
+
+	/*
+	 * Enables TX FIFO threashold irq when FIFO is enabled,
+	 * or TX empty irq when FIFO is disabled
+	 */
+	if (stm32_port->fifoen && stm32_port->txftcfg >= 0)
+		stm32_usart_set_bits(port, ofs->cr3, USART_CR3_TXFTIE);
+	else
+		stm32_usart_set_bits(port, ofs->cr1, USART_CR1_TXEIE);
+}
+
+static void stm32_usart_tc_interrupt_enable(struct uart_port *port)
+{
+	struct stm32_port *stm32_port = to_stm32_port(port);
+	const struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
+
+	stm32_usart_set_bits(port, ofs->cr1, USART_CR1_TCIE);
+}
+
+static void stm32_usart_rx_dma_complete(void *arg)
+{
+	struct uart_port *port = arg;
+	struct tty_port *tport = &port->state->port;
+	unsigned int size;
+	unsigned long flags;
+
+	spin_lock_irqsave(&port->lock, flags);
+	size = stm32_usart_receive_chars(port, false);
+	uart_unlock_and_check_sysrq_irqrestore(port, flags);
+	if (size)
+		tty_flip_buffer_push(tport);
+}
+
+static void stm32_usart_tx_interrupt_disable(struct uart_port *port)
+{
+	struct stm32_port *stm32_port = to_stm32_port(port);
+	const struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
+
+	if (stm32_port->fifoen && stm32_port->txftcfg >= 0)
+		stm32_usart_clr_bits(port, ofs->cr3, USART_CR3_TXFTIE);
+	else
+		stm32_usart_clr_bits(port, ofs->cr1, USART_CR1_TXEIE);
+}
+
+static void stm32_usart_tc_interrupt_disable(struct uart_port *port)
+{
+	struct stm32_port *stm32_port = to_stm32_port(port);
+	const struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
+
+	stm32_usart_clr_bits(port, ofs->cr1, USART_CR1_TCIE);
+}
+
+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;
+
+	if (stm32_usart_tx_dma_enabled(stm32_port))
+		stm32_usart_clr_bits(port, ofs->cr3, USART_CR3_DMAT);
+
+	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);
+		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
+		port->icount.tx++;
+	}
+
+	/* rely on TXE irq (mask or unmask) for sending remaining data */
+	if (uart_circ_empty(xmit))
+		stm32_usart_tx_interrupt_disable(port);
+	else
+		stm32_usart_tx_interrupt_enable(port);
+}
+
+static void stm32_usart_transmit_chars_dma(struct uart_port *port)
+{
+	struct stm32_port *stm32port = to_stm32_port(port);
+	const struct stm32_usart_offsets *ofs = &stm32port->info->ofs;
+	struct circ_buf *xmit = &port->state->xmit;
+	struct dma_async_tx_descriptor *desc = NULL;
+	unsigned int count;
+
+	if (stm32_usart_tx_dma_started(stm32port)) {
+		if (!stm32_usart_tx_dma_enabled(stm32port))
+			stm32_usart_set_bits(port, ofs->cr3, USART_CR3_DMAT);
+		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);
+	}
+
+	desc = dmaengine_prep_slave_single(stm32port->tx_ch,
+					   stm32port->tx_dma_buf,
+					   count,
+					   DMA_MEM_TO_DEV,
+					   DMA_PREP_INTERRUPT);
+
+	if (!desc)
+		goto fallback_err;
+
+	/*
+	 * Set "tx_dma_busy" flag. This flag will be released when
+	 * dmaengine_terminate_async will be called. This flag helps
+	 * transmit_chars_dma not to start another DMA transaction
+	 * if the callback of the previous is not yet called.
+	 */
+	stm32port->tx_dma_busy = true;
+
+	desc->callback = stm32_usart_tx_dma_complete;
+	desc->callback_param = port;
+
+	/* Push current DMA TX transaction in the pending queue */
+	if (dma_submit_error(dmaengine_submit(desc))) {
+		/* dma no yet started, safe to free resources */
+		stm32_usart_tx_dma_terminate(stm32port);
+		goto fallback_err;
+	}
+
+	/* Issue pending DMA TX requests */
+	dma_async_issue_pending(stm32port->tx_ch);
+
+	stm32_usart_set_bits(port, ofs->cr3, USART_CR3_DMAT);
+
+	xmit->tail = (xmit->tail + count) & (UART_XMIT_SIZE - 1);
+	port->icount.tx += count;
+	return;
+
+fallback_err:
+	stm32_usart_transmit_chars_pio(port);
+}
+
+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;
+	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)))) {
+		stm32_usart_tc_interrupt_disable(port);
+		stm32_usart_rs485_rts_enable(port);
+	}
+
+	if (port->x_char) {
+		if (stm32_usart_tx_dma_started(stm32_port) &&
+		    stm32_usart_tx_dma_enabled(stm32_port))
+			stm32_usart_clr_bits(port, ofs->cr3, USART_CR3_DMAT);
+
+		/* Check that TDR is empty before filling FIFO */
+		ret =
+		readl_relaxed_poll_timeout_atomic(port->membase + ofs->isr,
+						  isr,
+						  (isr & USART_SR_TXE),
+						  10, 1000);
+		if (ret)
+			dev_warn(port->dev, "1 character may be erased\n");
+
+		writel_relaxed(port->x_char, port->membase + ofs->tdr);
+		port->x_char = 0;
+		port->icount.tx++;
+		if (stm32_usart_tx_dma_started(stm32_port))
+			stm32_usart_set_bits(port, ofs->cr3, USART_CR3_DMAT);
+		return;
+	}
+
+	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
+		stm32_usart_tx_interrupt_disable(port);
+		return;
+	}
+
+	if (ofs->icr == UNDEF_REG)
+		stm32_usart_clr_bits(port, ofs->isr, USART_SR_TC);
+	else
+		writel_relaxed(USART_ICR_TCCF, port->membase + ofs->icr);
+
+	if (stm32_port->tx_ch)
+		stm32_usart_transmit_chars_dma(port);
+	else
+		stm32_usart_transmit_chars_pio(port);
+
+	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+		uart_write_wakeup(port);
+
+	if (uart_circ_empty(xmit)) {
+		stm32_usart_tx_interrupt_disable(port);
+		if (!stm32_port->hw_flow_control &&
+		    port->rs485.flags & SER_RS485_ENABLED) {
+			stm32_port->txdone = true;
+			stm32_usart_tc_interrupt_enable(port);
+		}
+	}
+}
+
+static irqreturn_t stm32_usart_interrupt(int irq, void *ptr)
+{
+	struct uart_port *port = ptr;
+	struct tty_port *tport = &port->state->port;
+	struct stm32_port *stm32_port = to_stm32_port(port);
+	const struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
+	u32 sr;
+	unsigned int size;
+
+	sr = readl_relaxed(port->membase + ofs->isr);
+
+	if (!stm32_port->hw_flow_control &&
+	    port->rs485.flags & SER_RS485_ENABLED &&
+	    (sr & USART_SR_TC)) {
+		stm32_usart_tc_interrupt_disable(port);
+		stm32_usart_rs485_rts_disable(port);
+	}
+
+	if ((sr & USART_SR_RTOF) && ofs->icr != UNDEF_REG)
+		writel_relaxed(USART_ICR_RTOCF,
+			       port->membase + ofs->icr);
+
+	if ((sr & USART_SR_WUF) && ofs->icr != UNDEF_REG) {
+		/* Clear wake up flag and disable wake up interrupt */
+		writel_relaxed(USART_ICR_WUCF,
+			       port->membase + ofs->icr);
+		stm32_usart_clr_bits(port, ofs->cr3, USART_CR3_WUFIE);
+		if (irqd_is_wakeup_set(irq_get_irq_data(port->irq)))
+			pm_wakeup_event(tport->tty->dev, 0);
+	}
+
+	/*
+	 * rx errors in dma mode has to be handled ASAP to avoid overrun as the DMA request
+	 * line has been masked by HW and rx data are stacking in FIFO.
+	 */
+	if (!stm32_port->throttled) {
+		if (((sr & USART_SR_RXNE) && !stm32_usart_rx_dma_enabled(port)) ||
+		    ((sr & USART_SR_ERR_MASK) && stm32_usart_rx_dma_enabled(port))) {
+			spin_lock(&port->lock);
+			size = stm32_usart_receive_chars(port, false);
+			uart_unlock_and_check_sysrq(port);
+			if (size)
+				tty_flip_buffer_push(tport);
+		}
+	}
+
+	if ((sr & USART_SR_TXE) && !(stm32_port->tx_ch)) {
+		spin_lock(&port->lock);
+		stm32_usart_transmit_chars(port);
+		spin_unlock(&port->lock);
+	}
+
+	/* Receiver timeout irq for DMA RX */
+	if (stm32_usart_rx_dma_enabled(port) && !stm32_port->throttled) {
+		spin_lock(&port->lock);
+		size = stm32_usart_receive_chars(port, false);
+		uart_unlock_and_check_sysrq(port);
+		if (size)
+			tty_flip_buffer_push(tport);
+	}
+
+	return IRQ_HANDLED;
+}
+
+static void stm32_usart_set_mctrl(struct uart_port *port, unsigned int mctrl)
+{
+	struct stm32_port *stm32_port = to_stm32_port(port);
+	const struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
+
+	if ((mctrl & TIOCM_RTS) && (port->status & UPSTAT_AUTORTS))
+		stm32_usart_set_bits(port, ofs->cr3, USART_CR3_RTSE);
+	else
+		stm32_usart_clr_bits(port, ofs->cr3, USART_CR3_RTSE);
+
+	mctrl_gpio_set(stm32_port->gpios, mctrl);
+}
+
+static unsigned int stm32_usart_get_mctrl(struct uart_port *port)
+{
+	struct stm32_port *stm32_port = to_stm32_port(port);
+	unsigned int ret;
+
+	/* This routine is used to get signals of: DCD, DSR, RI, and CTS */
+	ret = TIOCM_CAR | TIOCM_DSR | TIOCM_CTS;
+
+	return mctrl_gpio_get(stm32_port->gpios, &ret);
+}
+
+static void stm32_usart_enable_ms(struct uart_port *port)
+{
+	mctrl_gpio_enable_ms(to_stm32_port(port)->gpios);
+}
+
+static void stm32_usart_disable_ms(struct uart_port *port)
+{
+	mctrl_gpio_disable_ms(to_stm32_port(port)->gpios);
+}
+
+/* Transmit stop */
+static void stm32_usart_stop_tx(struct uart_port *port)
+{
+	struct stm32_port *stm32_port = to_stm32_port(port);
+	const struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
+
+	stm32_usart_tx_interrupt_disable(port);
+	if (stm32_usart_tx_dma_started(stm32_port) && stm32_usart_tx_dma_enabled(stm32_port))
+		stm32_usart_clr_bits(port, ofs->cr3, USART_CR3_DMAT);
+
+	stm32_usart_rs485_rts_disable(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;
+
+	if (uart_circ_empty(xmit) && !port->x_char) {
+		stm32_usart_rs485_rts_disable(port);
+		return;
+	}
+
+	stm32_usart_rs485_rts_enable(port);
+
+	stm32_usart_transmit_chars(port);
+}
+
+/* Flush the transmit buffer. */
+static void stm32_usart_flush_buffer(struct uart_port *port)
+{
+	struct stm32_port *stm32_port = to_stm32_port(port);
+	const struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
+
+	if (stm32_port->tx_ch) {
+		stm32_usart_tx_dma_terminate(stm32_port);
+		stm32_usart_clr_bits(port, ofs->cr3, USART_CR3_DMAT);
+	}
+}
+
+/* Throttle the remote when input buffer is about to overflow. */
+static void stm32_usart_throttle(struct uart_port *port)
+{
+	struct stm32_port *stm32_port = to_stm32_port(port);
+	const struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
+	unsigned long flags;
+
+	spin_lock_irqsave(&port->lock, flags);
+
+	/*
+	 * Disable DMA request line if enabled, so the RX data gets queued into the FIFO.
+	 * Hardware flow control is triggered when RX FIFO is full.
+	 */
+	if (stm32_usart_rx_dma_enabled(port))
+		stm32_usart_clr_bits(port, ofs->cr3, USART_CR3_DMAR);
+
+	stm32_usart_clr_bits(port, ofs->cr1, stm32_port->cr1_irq);
+	if (stm32_port->cr3_irq)
+		stm32_usart_clr_bits(port, ofs->cr3, stm32_port->cr3_irq);
+
+	stm32_port->throttled = true;
+	spin_unlock_irqrestore(&port->lock, flags);
+}
+
+/* Unthrottle the remote, the input buffer can now accept data. */
+static void stm32_usart_unthrottle(struct uart_port *port)
+{
+	struct stm32_port *stm32_port = to_stm32_port(port);
+	const struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
+	unsigned long flags;
+
+	spin_lock_irqsave(&port->lock, flags);
+	stm32_usart_set_bits(port, ofs->cr1, stm32_port->cr1_irq);
+	if (stm32_port->cr3_irq)
+		stm32_usart_set_bits(port, ofs->cr3, stm32_port->cr3_irq);
+
+	/*
+	 * Switch back to DMA mode (re-enable DMA request line).
+	 * Hardware flow control is stopped when FIFO is not full any more.
+	 */
+	if (stm32_port->rx_ch)
+		stm32_usart_set_bits(port, ofs->cr3, USART_CR3_DMAR);
+
+	stm32_port->throttled = false;
+	spin_unlock_irqrestore(&port->lock, flags);
+}
+
+/* Receive stop */
+static void stm32_usart_stop_rx(struct uart_port *port)
+{
+	struct stm32_port *stm32_port = to_stm32_port(port);
+	const struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
+
+	/* Disable DMA request line. */
+	if (stm32_port->rx_ch)
+		stm32_usart_clr_bits(port, ofs->cr3, USART_CR3_DMAR);
+
+	stm32_usart_clr_bits(port, ofs->cr1, stm32_port->cr1_irq);
+	if (stm32_port->cr3_irq)
+		stm32_usart_clr_bits(port, ofs->cr3, stm32_port->cr3_irq);
+}
+
+/* Handle breaks - ignored by us */
+static void stm32_usart_break_ctl(struct uart_port *port, int break_state)
+{
+}
+
+static int stm32_usart_start_rx_dma_cyclic(struct uart_port *port)
+{
+	struct stm32_port *stm32_port = to_stm32_port(port);
+	const struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
+	struct dma_async_tx_descriptor *desc;
+	int ret;
+
+	stm32_port->last_res = RX_BUF_L;
+	/* Prepare a DMA cyclic transaction */
+	desc = dmaengine_prep_dma_cyclic(stm32_port->rx_ch,
+					 stm32_port->rx_dma_buf,
+					 RX_BUF_L, RX_BUF_P,
+					 DMA_DEV_TO_MEM,
+					 DMA_PREP_INTERRUPT);
+	if (!desc) {
+		dev_err(port->dev, "rx dma prep cyclic failed\n");
+		return -ENODEV;
+	}
+
+	desc->callback = stm32_usart_rx_dma_complete;
+	desc->callback_param = port;
+
+	/* Push current DMA transaction in the pending queue */
+	ret = dma_submit_error(dmaengine_submit(desc));
+	if (ret) {
+		dmaengine_terminate_sync(stm32_port->rx_ch);
+		return ret;
+	}
+
+	/* Issue pending DMA requests */
+	dma_async_issue_pending(stm32_port->rx_ch);
+
+	/*
+	 * DMA request line not re-enabled at resume when port is throttled.
+	 * It will be re-enabled by unthrottle ops.
+	 */
+	if (!stm32_port->throttled)
+		stm32_usart_set_bits(port, ofs->cr3, USART_CR3_DMAR);
+
+	return 0;
+}
+
+static int stm32_usart_startup(struct uart_port *port)
+{
+	struct stm32_port *stm32_port = to_stm32_port(port);
+	const struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
+	const struct stm32_usart_config *cfg = &stm32_port->info->cfg;
+	const char *name = to_platform_device(port->dev)->name;
+	u32 val;
+	int ret;
+
+	ret = request_irq(port->irq, stm32_usart_interrupt,
+			  IRQF_NO_SUSPEND, name, port);
+	if (ret)
+		return ret;
+
+	if (stm32_port->swap) {
+		val = readl_relaxed(port->membase + ofs->cr2);
+		val |= USART_CR2_SWAP;
+		writel_relaxed(val, port->membase + ofs->cr2);
+	}
+
+	/* RX FIFO Flush */
+	if (ofs->rqr != UNDEF_REG)
+		writel_relaxed(USART_RQR_RXFRQ, port->membase + ofs->rqr);
+
+	if (stm32_port->rx_ch) {
+		ret = stm32_usart_start_rx_dma_cyclic(port);
+		if (ret) {
+			free_irq(port->irq, port);
+			return ret;
+		}
+	}
+
+	/* RX enabling */
+	val = stm32_port->cr1_irq | USART_CR1_RE | BIT(cfg->uart_enable_bit);
+	stm32_usart_set_bits(port, ofs->cr1, val);
+
+	return 0;
+}
+
+static void stm32_usart_shutdown(struct uart_port *port)
+{
+	struct stm32_port *stm32_port = to_stm32_port(port);
+	const struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
+	const struct stm32_usart_config *cfg = &stm32_port->info->cfg;
+	u32 val, isr;
+	int ret;
+
+	if (stm32_usart_tx_dma_enabled(stm32_port))
+		stm32_usart_clr_bits(port, ofs->cr3, USART_CR3_DMAT);
+
+	if (stm32_usart_tx_dma_started(stm32_port))
+		stm32_usart_tx_dma_terminate(stm32_port);
+
+	/* Disable modem control interrupts */
+	stm32_usart_disable_ms(port);
+
+	val = USART_CR1_TXEIE | USART_CR1_TE;
+	val |= stm32_port->cr1_irq | USART_CR1_RE;
+	val |= BIT(cfg->uart_enable_bit);
+	if (stm32_port->fifoen)
+		val |= USART_CR1_FIFOEN;
+
+	ret = readl_relaxed_poll_timeout(port->membase + ofs->isr,
+					 isr, (isr & USART_SR_TC),
+					 10, 100000);
+
+	/* Send the TC error message only when ISR_TC is not set */
+	if (ret)
+		dev_err(port->dev, "Transmission is not complete\n");
+
+	/* Disable RX DMA. */
+	if (stm32_port->rx_ch)
+		dmaengine_terminate_async(stm32_port->rx_ch);
+
+	/* flush RX & TX FIFO */
+	if (ofs->rqr != UNDEF_REG)
+		writel_relaxed(USART_RQR_TXFRQ | USART_RQR_RXFRQ,
+			       port->membase + ofs->rqr);
+
+	stm32_usart_clr_bits(port, ofs->cr1, val);
+
+	free_irq(port->irq, port);
+}
+
+static void stm32_usart_set_termios(struct uart_port *port,
+				    struct ktermios *termios,
+				    const struct ktermios *old)
+{
+	struct stm32_port *stm32_port = to_stm32_port(port);
+	const struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
+	const struct stm32_usart_config *cfg = &stm32_port->info->cfg;
+	struct serial_rs485 *rs485conf = &port->rs485;
+	unsigned int baud, bits;
+	u32 usartdiv, mantissa, fraction, oversampling;
+	tcflag_t cflag = termios->c_cflag;
+	u32 cr1, cr2, cr3, isr;
+	unsigned long flags;
+	int ret;
+
+	if (!stm32_port->hw_flow_control)
+		cflag &= ~CRTSCTS;
+
+	baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk / 8);
+
+	spin_lock_irqsave(&port->lock, flags);
+
+	ret = readl_relaxed_poll_timeout_atomic(port->membase + ofs->isr,
+						isr,
+						(isr & USART_SR_TC),
+						10, 100000);
+
+	/* Send the TC error message only when ISR_TC is not set. */
+	if (ret)
+		dev_err(port->dev, "Transmission is not complete\n");
+
+	/* Stop serial port and reset value */
+	writel_relaxed(0, port->membase + ofs->cr1);
+
+	/* flush RX & TX FIFO */
+	if (ofs->rqr != UNDEF_REG)
+		writel_relaxed(USART_RQR_TXFRQ | USART_RQR_RXFRQ,
+			       port->membase + ofs->rqr);
+
+	cr1 = USART_CR1_TE | USART_CR1_RE;
+	if (stm32_port->fifoen)
+		cr1 |= USART_CR1_FIFOEN;
+	cr2 = stm32_port->swap ? USART_CR2_SWAP : 0;
+
+	/* Tx and RX FIFO configuration */
+	cr3 = readl_relaxed(port->membase + ofs->cr3);
+	cr3 &= USART_CR3_TXFTIE | USART_CR3_RXFTIE;
+	if (stm32_port->fifoen) {
+		if (stm32_port->txftcfg >= 0)
+			cr3 |= stm32_port->txftcfg << USART_CR3_TXFTCFG_SHIFT;
+		if (stm32_port->rxftcfg >= 0)
+			cr3 |= stm32_port->rxftcfg << USART_CR3_RXFTCFG_SHIFT;
+	}
+
+	if (cflag & CSTOPB)
+		cr2 |= USART_CR2_STOP_2B;
+
+	bits = tty_get_char_size(cflag);
+	stm32_port->rdr_mask = (BIT(bits) - 1);
+
+	if (cflag & PARENB) {
+		bits++;
+		cr1 |= USART_CR1_PCE;
+	}
+
+	/*
+	 * Word length configuration:
+	 * CS8 + parity, 9 bits word aka [M1:M0] = 0b01
+	 * CS7 or (CS6 + parity), 7 bits word aka [M1:M0] = 0b10
+	 * CS8 or (CS7 + parity), 8 bits word aka [M1:M0] = 0b00
+	 * M0 and M1 already cleared by cr1 initialization.
+	 */
+	if (bits == 9) {
+		cr1 |= USART_CR1_M0;
+	} else if ((bits == 7) && cfg->has_7bits_data) {
+		cr1 |= USART_CR1_M1;
+	} else if (bits != 8) {
+		dev_dbg(port->dev, "Unsupported data bits config: %u bits\n"
+			, bits);
+		cflag &= ~CSIZE;
+		cflag |= CS8;
+		termios->c_cflag = cflag;
+		bits = 8;
+		if (cflag & PARENB) {
+			bits++;
+			cr1 |= USART_CR1_M0;
+		}
+	}
+
+	if (ofs->rtor != UNDEF_REG && (stm32_port->rx_ch ||
+				       (stm32_port->fifoen &&
+					stm32_port->rxftcfg >= 0))) {
+		if (cflag & CSTOPB)
+			bits = bits + 3; /* 1 start bit + 2 stop bits */
+		else
+			bits = bits + 2; /* 1 start bit + 1 stop bit */
+
+		/* RX timeout irq to occur after last stop bit + bits */
+		stm32_port->cr1_irq = USART_CR1_RTOIE;
+		writel_relaxed(bits, port->membase + ofs->rtor);
+		cr2 |= USART_CR2_RTOEN;
+		/*
+		 * Enable fifo threshold irq in two cases, either when there is no DMA, or when
+		 * wake up over usart, from low power until the DMA gets re-enabled by resume.
+		 */
+		stm32_port->cr3_irq =  USART_CR3_RXFTIE;
+	}
+
+	cr1 |= stm32_port->cr1_irq;
+	cr3 |= stm32_port->cr3_irq;
+
+	if (cflag & PARODD)
+		cr1 |= USART_CR1_PS;
+
+	port->status &= ~(UPSTAT_AUTOCTS | UPSTAT_AUTORTS);
+	if (cflag & CRTSCTS) {
+		port->status |= UPSTAT_AUTOCTS | UPSTAT_AUTORTS;
+		cr3 |= USART_CR3_CTSE | USART_CR3_RTSE;
+	}
+
+	usartdiv = DIV_ROUND_CLOSEST(port->uartclk, baud);
+
+	/*
+	 * The USART supports 16 or 8 times oversampling.
+	 * By default we prefer 16 times oversampling, so that the receiver
+	 * has a better tolerance to clock deviations.
+	 * 8 times oversampling is only used to achieve higher speeds.
+	 */
+	if (usartdiv < 16) {
+		oversampling = 8;
+		cr1 |= USART_CR1_OVER8;
+		stm32_usart_set_bits(port, ofs->cr1, USART_CR1_OVER8);
+	} else {
+		oversampling = 16;
+		cr1 &= ~USART_CR1_OVER8;
+		stm32_usart_clr_bits(port, ofs->cr1, USART_CR1_OVER8);
+	}
+
+	mantissa = (usartdiv / oversampling) << USART_BRR_DIV_M_SHIFT;
+	fraction = usartdiv % oversampling;
+	writel_relaxed(mantissa | fraction, port->membase + ofs->brr);
+
+	uart_update_timeout(port, cflag, baud);
+
+	port->read_status_mask = USART_SR_ORE;
+	if (termios->c_iflag & INPCK)
+		port->read_status_mask |= USART_SR_PE | USART_SR_FE;
+	if (termios->c_iflag & (IGNBRK | BRKINT | PARMRK))
+		port->read_status_mask |= USART_SR_FE;
+
+	/* Characters to ignore */
+	port->ignore_status_mask = 0;
+	if (termios->c_iflag & IGNPAR)
+		port->ignore_status_mask = USART_SR_PE | USART_SR_FE;
+	if (termios->c_iflag & IGNBRK) {
+		port->ignore_status_mask |= USART_SR_FE;
+		/*
+		 * If we're ignoring parity and break indicators,
+		 * ignore overruns too (for real raw support).
+		 */
+		if (termios->c_iflag & IGNPAR)
+			port->ignore_status_mask |= USART_SR_ORE;
+	}
+
+	/* Ignore all characters if CREAD is not set */
+	if ((termios->c_cflag & CREAD) == 0)
+		port->ignore_status_mask |= USART_SR_DUMMY_RX;
+
+	if (stm32_port->rx_ch) {
+		/*
+		 * Setup DMA to collect only valid data and enable error irqs.
+		 * This also enables break reception when using DMA.
+		 */
+		cr1 |= USART_CR1_PEIE;
+		cr3 |= USART_CR3_EIE;
+		cr3 |= USART_CR3_DMAR;
+		cr3 |= USART_CR3_DDRE;
+	}
+
+	if (rs485conf->flags & SER_RS485_ENABLED) {
+		stm32_usart_config_reg_rs485(&cr1, &cr3,
+					     rs485conf->delay_rts_before_send,
+					     rs485conf->delay_rts_after_send,
+					     baud);
+		if (rs485conf->flags & SER_RS485_RTS_ON_SEND) {
+			cr3 &= ~USART_CR3_DEP;
+			rs485conf->flags &= ~SER_RS485_RTS_AFTER_SEND;
+		} else {
+			cr3 |= USART_CR3_DEP;
+			rs485conf->flags |= SER_RS485_RTS_AFTER_SEND;
+		}
+
+	} else {
+		cr3 &= ~(USART_CR3_DEM | USART_CR3_DEP);
+		cr1 &= ~(USART_CR1_DEDT_MASK | USART_CR1_DEAT_MASK);
+	}
+
+	/* Configure wake up from low power on start bit detection */
+	if (stm32_port->wakeup_src) {
+		cr3 &= ~USART_CR3_WUS_MASK;
+		cr3 |= USART_CR3_WUS_START_BIT;
+	}
+
+	writel_relaxed(cr3, port->membase + ofs->cr3);
+	writel_relaxed(cr2, port->membase + ofs->cr2);
+	writel_relaxed(cr1, port->membase + ofs->cr1);
+
+	stm32_usart_set_bits(port, ofs->cr1, BIT(cfg->uart_enable_bit));
+	spin_unlock_irqrestore(&port->lock, flags);
+
+	/* Handle modem control interrupts */
+	if (UART_ENABLE_MS(port, termios->c_cflag))
+		stm32_usart_enable_ms(port);
+	else
+		stm32_usart_disable_ms(port);
+}
+
+static const char *stm32_usart_type(struct uart_port *port)
+{
+	return (port->type == PORT_STM32) ? DRIVER_NAME : NULL;
+}
+
+static void stm32_usart_release_port(struct uart_port *port)
+{
+}
+
+static int stm32_usart_request_port(struct uart_port *port)
+{
+	return 0;
+}
+
+static void stm32_usart_config_port(struct uart_port *port, int flags)
+{
+	if (flags & UART_CONFIG_TYPE)
+		port->type = PORT_STM32;
+}
+
+static int
+stm32_usart_verify_port(struct uart_port *port, struct serial_struct *ser)
+{
+	/* No user changeable parameters */
+	return -EINVAL;
+}
+
+static void stm32_usart_pm(struct uart_port *port, unsigned int state,
+			   unsigned int oldstate)
+{
+	struct stm32_port *stm32port = container_of(port,
+			struct stm32_port, port);
+	const struct stm32_usart_offsets *ofs = &stm32port->info->ofs;
+	const struct stm32_usart_config *cfg = &stm32port->info->cfg;
+	unsigned long flags;
+
+	switch (state) {
+	case UART_PM_STATE_ON:
+		pm_runtime_get_sync(port->dev);
+		break;
+	case UART_PM_STATE_OFF:
+		spin_lock_irqsave(&port->lock, flags);
+		stm32_usart_clr_bits(port, ofs->cr1, BIT(cfg->uart_enable_bit));
+		spin_unlock_irqrestore(&port->lock, flags);
+		pm_runtime_put_sync(port->dev);
+		break;
+	}
+}
+
+#if defined(CONFIG_CONSOLE_POLL)
+
+ /* Callbacks for characters polling in debug context (i.e. KGDB). */
+static int stm32_usart_poll_init(struct uart_port *port)
+{
+	struct stm32_port *stm32_port = to_stm32_port(port);
+
+	return clk_prepare_enable(stm32_port->clk);
+}
+
+static int stm32_usart_poll_get_char(struct uart_port *port)
+{
+	struct stm32_port *stm32_port = to_stm32_port(port);
+	const struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
+
+	if (!(readl_relaxed(port->membase + ofs->isr) & USART_SR_RXNE))
+		return NO_POLL_CHAR;
+
+	return readl_relaxed(port->membase + ofs->rdr) & stm32_port->rdr_mask;
+}
+
+static void stm32_usart_poll_put_char(struct uart_port *port, unsigned char ch)
+{
+	stm32_usart_console_putchar(port, ch);
+}
+#endif /* CONFIG_CONSOLE_POLL */
+
+static const struct uart_ops stm32_uart_ops = {
+	.tx_empty	= stm32_usart_tx_empty,
+	.set_mctrl	= stm32_usart_set_mctrl,
+	.get_mctrl	= stm32_usart_get_mctrl,
+	.stop_tx	= stm32_usart_stop_tx,
+	.start_tx	= stm32_usart_start_tx,
+	.throttle	= stm32_usart_throttle,
+	.unthrottle	= stm32_usart_unthrottle,
+	.stop_rx	= stm32_usart_stop_rx,
+	.enable_ms	= stm32_usart_enable_ms,
+	.break_ctl	= stm32_usart_break_ctl,
+	.startup	= stm32_usart_startup,
+	.shutdown	= stm32_usart_shutdown,
+	.flush_buffer	= stm32_usart_flush_buffer,
+	.set_termios	= stm32_usart_set_termios,
+	.pm		= stm32_usart_pm,
+	.type		= stm32_usart_type,
+	.release_port	= stm32_usart_release_port,
+	.request_port	= stm32_usart_request_port,
+	.config_port	= stm32_usart_config_port,
+	.verify_port	= stm32_usart_verify_port,
+#if defined(CONFIG_CONSOLE_POLL)
+	.poll_init      = stm32_usart_poll_init,
+	.poll_get_char	= stm32_usart_poll_get_char,
+	.poll_put_char	= stm32_usart_poll_put_char,
+#endif /* CONFIG_CONSOLE_POLL */
+};
+
+/*
+ * STM32H7 RX & TX FIFO threshold configuration (CR3 RXFTCFG / TXFTCFG)
+ * Note: 1 isn't a valid value in RXFTCFG / TXFTCFG. In this case,
+ * RXNEIE / TXEIE can be used instead of threshold irqs: RXFTIE / TXFTIE.
+ * So, RXFTCFG / TXFTCFG bitfields values are encoded as array index + 1.
+ */
+static const u32 stm32h7_usart_fifo_thresh_cfg[] = { 1, 2, 4, 8, 12, 14, 16 };
+
+static void stm32_usart_get_ftcfg(struct platform_device *pdev, const char *p,
+				  int *ftcfg)
+{
+	u32 bytes, i;
+
+	/* DT option to get RX & TX FIFO threshold (default to 8 bytes) */
+	if (of_property_read_u32(pdev->dev.of_node, p, &bytes))
+		bytes = 8;
+
+	for (i = 0; i < ARRAY_SIZE(stm32h7_usart_fifo_thresh_cfg); i++)
+		if (stm32h7_usart_fifo_thresh_cfg[i] >= bytes)
+			break;
+	if (i >= ARRAY_SIZE(stm32h7_usart_fifo_thresh_cfg))
+		i = ARRAY_SIZE(stm32h7_usart_fifo_thresh_cfg) - 1;
+
+	dev_dbg(&pdev->dev, "%s set to %d bytes\n", p,
+		stm32h7_usart_fifo_thresh_cfg[i]);
+
+	/* Provide FIFO threshold ftcfg (1 is invalid: threshold irq unused) */
+	if (i)
+		*ftcfg = i - 1;
+	else
+		*ftcfg = -EINVAL;
+}
+
+static void stm32_usart_deinit_port(struct stm32_port *stm32port)
+{
+	clk_disable_unprepare(stm32port->clk);
+}
+
+static const struct serial_rs485 stm32_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,
+};
+
+static int stm32_usart_init_port(struct stm32_port *stm32port,
+				 struct platform_device *pdev)
+{
+	struct uart_port *port = &stm32port->port;
+	struct resource *res;
+	int ret, irq;
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0)
+		return irq;
+
+	port->iotype	= UPIO_MEM;
+	port->flags	= UPF_BOOT_AUTOCONF;
+	port->ops	= &stm32_uart_ops;
+	port->dev	= &pdev->dev;
+	port->fifosize	= stm32port->info->cfg.fifosize;
+	port->has_sysrq = IS_ENABLED(CONFIG_SERIAL_STM32_CONSOLE);
+	port->irq = irq;
+	port->rs485_config = stm32_usart_config_rs485;
+	port->rs485_supported = stm32_rs485_supported;
+
+	ret = stm32_usart_init_rs485(port, pdev);
+	if (ret)
+		return ret;
+
+	stm32port->wakeup_src = stm32port->info->cfg.has_wakeup &&
+		of_property_read_bool(pdev->dev.of_node, "wakeup-source");
+
+	stm32port->swap = stm32port->info->cfg.has_swap &&
+		of_property_read_bool(pdev->dev.of_node, "rx-tx-swap");
+
+	stm32port->fifoen = stm32port->info->cfg.has_fifo;
+	if (stm32port->fifoen) {
+		stm32_usart_get_ftcfg(pdev, "rx-threshold",
+				      &stm32port->rxftcfg);
+		stm32_usart_get_ftcfg(pdev, "tx-threshold",
+				      &stm32port->txftcfg);
+	}
+
+	port->membase = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
+	if (IS_ERR(port->membase))
+		return PTR_ERR(port->membase);
+	port->mapbase = res->start;
+
+	spin_lock_init(&port->lock);
+
+	stm32port->clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(stm32port->clk))
+		return PTR_ERR(stm32port->clk);
+
+	/* Ensure that clk rate is correct by enabling the clk */
+	ret = clk_prepare_enable(stm32port->clk);
+	if (ret)
+		return ret;
+
+	stm32port->port.uartclk = clk_get_rate(stm32port->clk);
+	if (!stm32port->port.uartclk) {
+		ret = -EINVAL;
+		goto err_clk;
+	}
+
+	stm32port->gpios = mctrl_gpio_init(&stm32port->port, 0);
+	if (IS_ERR(stm32port->gpios)) {
+		ret = PTR_ERR(stm32port->gpios);
+		goto err_clk;
+	}
+
+	/*
+	 * Both CTS/RTS gpios and "st,hw-flow-ctrl" (deprecated) or "uart-has-rtscts"
+	 * properties should not be specified.
+	 */
+	if (stm32port->hw_flow_control) {
+		if (mctrl_gpio_to_gpiod(stm32port->gpios, UART_GPIO_CTS) ||
+		    mctrl_gpio_to_gpiod(stm32port->gpios, UART_GPIO_RTS)) {
+			dev_err(&pdev->dev, "Conflicting RTS/CTS config\n");
+			ret = -EINVAL;
+			goto err_clk;
+		}
+	}
+
+	return ret;
+
+err_clk:
+	clk_disable_unprepare(stm32port->clk);
+
+	return ret;
+}
+
+static struct stm32_port *stm32_usart_of_get_port(struct platform_device *pdev)
+{
+	struct device_node *np = pdev->dev.of_node;
+	int id;
+
+	if (!np)
+		return NULL;
+
+	id = of_alias_get_id(np, "serial");
+	if (id < 0) {
+		dev_err(&pdev->dev, "failed to get alias id, errno %d\n", id);
+		return NULL;
+	}
+
+	if (WARN_ON(id >= STM32_MAX_PORTS))
+		return NULL;
+
+	stm32_ports[id].hw_flow_control =
+		of_property_read_bool (np, "st,hw-flow-ctrl") /*deprecated*/ ||
+		of_property_read_bool (np, "uart-has-rtscts");
+	stm32_ports[id].port.line = id;
+	stm32_ports[id].cr1_irq = USART_CR1_RXNEIE;
+	stm32_ports[id].cr3_irq = 0;
+	stm32_ports[id].last_res = RX_BUF_L;
+	return &stm32_ports[id];
+}
+
+#ifdef CONFIG_OF
+static const struct of_device_id stm32_match[] = {
+	{ .compatible = "st,stm32-uart", .data = &stm32f4_info},
+	{ .compatible = "st,stm32f7-uart", .data = &stm32f7_info},
+	{ .compatible = "st,stm32h7-uart", .data = &stm32h7_info},
+	{},
+};
+
+MODULE_DEVICE_TABLE(of, stm32_match);
+#endif
+
+static void stm32_usart_of_dma_rx_remove(struct stm32_port *stm32port,
+					 struct platform_device *pdev)
+{
+	if (stm32port->rx_buf)
+		dma_free_coherent(&pdev->dev, RX_BUF_L, stm32port->rx_buf,
+				  stm32port->rx_dma_buf);
+}
+
+static int stm32_usart_of_dma_rx_probe(struct stm32_port *stm32port,
+				       struct platform_device *pdev)
+{
+	const struct stm32_usart_offsets *ofs = &stm32port->info->ofs;
+	struct uart_port *port = &stm32port->port;
+	struct device *dev = &pdev->dev;
+	struct dma_slave_config config;
+	int ret;
+
+	stm32port->rx_buf = dma_alloc_coherent(dev, RX_BUF_L,
+					       &stm32port->rx_dma_buf,
+					       GFP_KERNEL);
+	if (!stm32port->rx_buf)
+		return -ENOMEM;
+
+	/* Configure DMA channel */
+	memset(&config, 0, sizeof(config));
+	config.src_addr = port->mapbase + ofs->rdr;
+	config.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
+
+	ret = dmaengine_slave_config(stm32port->rx_ch, &config);
+	if (ret < 0) {
+		dev_err(dev, "rx dma channel config failed\n");
+		stm32_usart_of_dma_rx_remove(stm32port, pdev);
+		return ret;
+	}
+
+	return 0;
+}
+
+static void stm32_usart_of_dma_tx_remove(struct stm32_port *stm32port,
+					 struct platform_device *pdev)
+{
+	if (stm32port->tx_buf)
+		dma_free_coherent(&pdev->dev, TX_BUF_L, stm32port->tx_buf,
+				  stm32port->tx_dma_buf);
+}
+
+static int stm32_usart_of_dma_tx_probe(struct stm32_port *stm32port,
+				       struct platform_device *pdev)
+{
+	const struct stm32_usart_offsets *ofs = &stm32port->info->ofs;
+	struct uart_port *port = &stm32port->port;
+	struct device *dev = &pdev->dev;
+	struct dma_slave_config config;
+	int ret;
+
+	stm32port->tx_buf = dma_alloc_coherent(dev, TX_BUF_L,
+					       &stm32port->tx_dma_buf,
+					       GFP_KERNEL);
+	if (!stm32port->tx_buf)
+		return -ENOMEM;
+
+	/* Configure DMA channel */
+	memset(&config, 0, sizeof(config));
+	config.dst_addr = port->mapbase + ofs->tdr;
+	config.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
+
+	ret = dmaengine_slave_config(stm32port->tx_ch, &config);
+	if (ret < 0) {
+		dev_err(dev, "tx dma channel config failed\n");
+		stm32_usart_of_dma_tx_remove(stm32port, pdev);
+		return ret;
+	}
+
+	return 0;
+}
+
+static int stm32_usart_serial_probe(struct platform_device *pdev)
+{
+	struct stm32_port *stm32port;
+	int ret;
+
+	stm32port = stm32_usart_of_get_port(pdev);
+	if (!stm32port)
+		return -ENODEV;
+
+	stm32port->info = of_device_get_match_data(&pdev->dev);
+	if (!stm32port->info)
+		return -EINVAL;
+
+	stm32port->rx_ch = dma_request_chan(&pdev->dev, "rx");
+	if (PTR_ERR(stm32port->rx_ch) == -EPROBE_DEFER)
+		return -EPROBE_DEFER;
+
+	/* Fall back in interrupt mode for any non-deferral error */
+	if (IS_ERR(stm32port->rx_ch))
+		stm32port->rx_ch = NULL;
+
+	stm32port->tx_ch = dma_request_chan(&pdev->dev, "tx");
+	if (PTR_ERR(stm32port->tx_ch) == -EPROBE_DEFER) {
+		ret = -EPROBE_DEFER;
+		goto err_dma_rx;
+	}
+	/* Fall back in interrupt mode for any non-deferral error */
+	if (IS_ERR(stm32port->tx_ch))
+		stm32port->tx_ch = NULL;
+
+	ret = stm32_usart_init_port(stm32port, pdev);
+	if (ret)
+		goto err_dma_tx;
+
+	if (stm32port->wakeup_src) {
+		device_set_wakeup_capable(&pdev->dev, true);
+		ret = dev_pm_set_wake_irq(&pdev->dev, stm32port->port.irq);
+		if (ret)
+			goto err_deinit_port;
+	}
+
+	if (stm32port->rx_ch && stm32_usart_of_dma_rx_probe(stm32port, pdev)) {
+		/* Fall back in interrupt mode */
+		dma_release_channel(stm32port->rx_ch);
+		stm32port->rx_ch = NULL;
+	}
+
+	if (stm32port->tx_ch && stm32_usart_of_dma_tx_probe(stm32port, pdev)) {
+		/* Fall back in interrupt mode */
+		dma_release_channel(stm32port->tx_ch);
+		stm32port->tx_ch = NULL;
+	}
+
+	if (!stm32port->rx_ch)
+		dev_info(&pdev->dev, "interrupt mode for rx (no dma)\n");
+	if (!stm32port->tx_ch)
+		dev_info(&pdev->dev, "interrupt mode for tx (no dma)\n");
+
+	platform_set_drvdata(pdev, &stm32port->port);
+
+	pm_runtime_get_noresume(&pdev->dev);
+	pm_runtime_set_active(&pdev->dev);
+	pm_runtime_enable(&pdev->dev);
+
+	ret = uart_add_one_port(&stm32_usart_driver, &stm32port->port);
+	if (ret)
+		goto err_port;
+
+	pm_runtime_put_sync(&pdev->dev);
+
+	return 0;
+
+err_port:
+	pm_runtime_disable(&pdev->dev);
+	pm_runtime_set_suspended(&pdev->dev);
+	pm_runtime_put_noidle(&pdev->dev);
+
+	if (stm32port->tx_ch)
+		stm32_usart_of_dma_tx_remove(stm32port, pdev);
+	if (stm32port->rx_ch)
+		stm32_usart_of_dma_rx_remove(stm32port, pdev);
+
+	if (stm32port->wakeup_src)
+		dev_pm_clear_wake_irq(&pdev->dev);
+
+err_deinit_port:
+	if (stm32port->wakeup_src)
+		device_set_wakeup_capable(&pdev->dev, false);
+
+	stm32_usart_deinit_port(stm32port);
+
+err_dma_tx:
+	if (stm32port->tx_ch)
+		dma_release_channel(stm32port->tx_ch);
+
+err_dma_rx:
+	if (stm32port->rx_ch)
+		dma_release_channel(stm32port->rx_ch);
+
+	return ret;
+}
+
+static int stm32_usart_serial_remove(struct platform_device *pdev)
+{
+	struct uart_port *port = platform_get_drvdata(pdev);
+	struct stm32_port *stm32_port = to_stm32_port(port);
+	const struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
+	u32 cr3;
+
+	pm_runtime_get_sync(&pdev->dev);
+	uart_remove_one_port(&stm32_usart_driver, port);
+
+	pm_runtime_disable(&pdev->dev);
+	pm_runtime_set_suspended(&pdev->dev);
+	pm_runtime_put_noidle(&pdev->dev);
+
+	stm32_usart_clr_bits(port, ofs->cr1, USART_CR1_PEIE);
+	cr3 = readl_relaxed(port->membase + ofs->cr3);
+	cr3 &= ~USART_CR3_EIE;
+	cr3 &= ~USART_CR3_DMAR;
+	cr3 &= ~USART_CR3_DDRE;
+	writel_relaxed(cr3, port->membase + ofs->cr3);
+
+	if (stm32_port->tx_ch) {
+		stm32_usart_of_dma_tx_remove(stm32_port, pdev);
+		dma_release_channel(stm32_port->tx_ch);
+	}
+
+	if (stm32_port->rx_ch) {
+		stm32_usart_of_dma_rx_remove(stm32_port, pdev);
+		dma_release_channel(stm32_port->rx_ch);
+	}
+
+	stm32_usart_clr_bits(port, ofs->cr3, USART_CR3_DMAT);
+
+	if (stm32_port->wakeup_src) {
+		dev_pm_clear_wake_irq(&pdev->dev);
+		device_init_wakeup(&pdev->dev, false);
+	}
+
+	stm32_usart_deinit_port(stm32_port);
+
+	return 0;
+}
+
+static void __maybe_unused stm32_usart_console_putchar(struct uart_port *port, unsigned char ch)
+{
+	struct stm32_port *stm32_port = to_stm32_port(port);
+	const struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
+	u32 isr;
+	int ret;
+
+	ret = readl_relaxed_poll_timeout_atomic(port->membase + ofs->isr, isr,
+						(isr & USART_SR_TXE), 100,
+						STM32_USART_TIMEOUT_USEC);
+	if (ret != 0) {
+		dev_err(port->dev, "Error while sending data in UART TX : %d\n", ret);
+		return;
+	}
+	writel_relaxed(ch, port->membase + ofs->tdr);
+}
+
+#ifdef CONFIG_SERIAL_STM32_CONSOLE
+static void stm32_usart_console_write(struct console *co, const char *s,
+				      unsigned int cnt)
+{
+	struct uart_port *port = &stm32_ports[co->index].port;
+	struct stm32_port *stm32_port = to_stm32_port(port);
+	const struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
+	const struct stm32_usart_config *cfg = &stm32_port->info->cfg;
+	unsigned long flags;
+	u32 old_cr1, new_cr1;
+	int locked = 1;
+
+	if (oops_in_progress)
+		locked = spin_trylock_irqsave(&port->lock, flags);
+	else
+		spin_lock_irqsave(&port->lock, flags);
+
+	/* Save and disable interrupts, enable the transmitter */
+	old_cr1 = readl_relaxed(port->membase + ofs->cr1);
+	new_cr1 = old_cr1 & ~USART_CR1_IE_MASK;
+	new_cr1 |=  USART_CR1_TE | BIT(cfg->uart_enable_bit);
+	writel_relaxed(new_cr1, port->membase + ofs->cr1);
+
+	uart_console_write(port, s, cnt, stm32_usart_console_putchar);
+
+	/* Restore interrupt state */
+	writel_relaxed(old_cr1, port->membase + ofs->cr1);
+
+	if (locked)
+		spin_unlock_irqrestore(&port->lock, flags);
+}
+
+static int stm32_usart_console_setup(struct console *co, char *options)
+{
+	struct stm32_port *stm32port;
+	int baud = 9600;
+	int bits = 8;
+	int parity = 'n';
+	int flow = 'n';
+
+	if (co->index >= STM32_MAX_PORTS)
+		return -ENODEV;
+
+	stm32port = &stm32_ports[co->index];
+
+	/*
+	 * This driver does not support early console initialization
+	 * (use ARM early printk support instead), so we only expect
+	 * this to be called during the uart port registration when the
+	 * driver gets probed and the port should be mapped at that point.
+	 */
+	if (stm32port->port.mapbase == 0 || !stm32port->port.membase)
+		return -ENXIO;
+
+	if (options)
+		uart_parse_options(options, &baud, &parity, &bits, &flow);
+
+	return uart_set_options(&stm32port->port, co, baud, parity, bits, flow);
+}
+
+static struct console stm32_console = {
+	.name		= STM32_SERIAL_NAME,
+	.device		= uart_console_device,
+	.write		= stm32_usart_console_write,
+	.setup		= stm32_usart_console_setup,
+	.flags		= CON_PRINTBUFFER,
+	.index		= -1,
+	.data		= &stm32_usart_driver,
+};
+
+#define STM32_SERIAL_CONSOLE (&stm32_console)
+
+#else
+#define STM32_SERIAL_CONSOLE NULL
+#endif /* CONFIG_SERIAL_STM32_CONSOLE */
+
+#ifdef CONFIG_SERIAL_EARLYCON
+static void early_stm32_usart_console_putchar(struct uart_port *port, unsigned char ch)
+{
+	struct stm32_usart_info *info = port->private_data;
+
+	while (!(readl_relaxed(port->membase + info->ofs.isr) & USART_SR_TXE))
+		cpu_relax();
+
+	writel_relaxed(ch, port->membase + info->ofs.tdr);
+}
+
+static void early_stm32_serial_write(struct console *console, const char *s, unsigned int count)
+{
+	struct earlycon_device *device = console->data;
+	struct uart_port *port = &device->port;
+
+	uart_console_write(port, s, count, early_stm32_usart_console_putchar);
+}
+
+static int __init early_stm32_h7_serial_setup(struct earlycon_device *device, const char *options)
+{
+	if (!(device->port.membase || device->port.iobase))
+		return -ENODEV;
+	device->port.private_data = &stm32h7_info;
+	device->con->write = early_stm32_serial_write;
+	return 0;
+}
+
+static int __init early_stm32_f7_serial_setup(struct earlycon_device *device, const char *options)
+{
+	if (!(device->port.membase || device->port.iobase))
+		return -ENODEV;
+	device->port.private_data = &stm32f7_info;
+	device->con->write = early_stm32_serial_write;
+	return 0;
+}
+
+static int __init early_stm32_f4_serial_setup(struct earlycon_device *device, const char *options)
+{
+	if (!(device->port.membase || device->port.iobase))
+		return -ENODEV;
+	device->port.private_data = &stm32f4_info;
+	device->con->write = early_stm32_serial_write;
+	return 0;
+}
+
+OF_EARLYCON_DECLARE(stm32, "st,stm32h7-uart", early_stm32_h7_serial_setup);
+OF_EARLYCON_DECLARE(stm32, "st,stm32f7-uart", early_stm32_f7_serial_setup);
+OF_EARLYCON_DECLARE(stm32, "st,stm32-uart", early_stm32_f4_serial_setup);
+#endif /* CONFIG_SERIAL_EARLYCON */
+
+static struct uart_driver stm32_usart_driver = {
+	.driver_name	= DRIVER_NAME,
+	.dev_name	= STM32_SERIAL_NAME,
+	.major		= 0,
+	.minor		= 0,
+	.nr		= STM32_MAX_PORTS,
+	.cons		= STM32_SERIAL_CONSOLE,
+};
+
+static int __maybe_unused stm32_usart_serial_en_wakeup(struct uart_port *port,
+						       bool enable)
+{
+	struct stm32_port *stm32_port = to_stm32_port(port);
+	const struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
+	struct tty_port *tport = &port->state->port;
+	int ret;
+	unsigned int size;
+	unsigned long flags;
+
+	if (!stm32_port->wakeup_src || !tty_port_initialized(tport))
+		return 0;
+
+	/*
+	 * Enable low-power wake-up and wake-up irq if argument is set to
+	 * "enable", disable low-power wake-up and wake-up irq otherwise
+	 */
+	if (enable) {
+		stm32_usart_set_bits(port, ofs->cr1, USART_CR1_UESM);
+		stm32_usart_set_bits(port, ofs->cr3, USART_CR3_WUFIE);
+		mctrl_gpio_enable_irq_wake(stm32_port->gpios);
+
+		/*
+		 * When DMA is used for reception, it must be disabled before
+		 * entering low-power mode and re-enabled when exiting from
+		 * low-power mode.
+		 */
+		if (stm32_port->rx_ch) {
+			spin_lock_irqsave(&port->lock, flags);
+			/* Avoid race with RX IRQ when DMAR is cleared */
+			stm32_usart_clr_bits(port, ofs->cr3, USART_CR3_DMAR);
+			/* Poll data from DMA RX buffer if any */
+			size = stm32_usart_receive_chars(port, true);
+			dmaengine_terminate_async(stm32_port->rx_ch);
+			uart_unlock_and_check_sysrq_irqrestore(port, flags);
+			if (size)
+				tty_flip_buffer_push(tport);
+		}
+
+		/* Poll data from RX FIFO if any */
+		stm32_usart_receive_chars(port, false);
+	} else {
+		if (stm32_port->rx_ch) {
+			ret = stm32_usart_start_rx_dma_cyclic(port);
+			if (ret)
+				return ret;
+		}
+		mctrl_gpio_disable_irq_wake(stm32_port->gpios);
+		stm32_usart_clr_bits(port, ofs->cr1, USART_CR1_UESM);
+		stm32_usart_clr_bits(port, ofs->cr3, USART_CR3_WUFIE);
+	}
+
+	return 0;
+}
+
+static int __maybe_unused stm32_usart_serial_suspend(struct device *dev)
+{
+	struct uart_port *port = dev_get_drvdata(dev);
+	int ret;
+
+	uart_suspend_port(&stm32_usart_driver, port);
+
+	if (device_may_wakeup(dev) || device_wakeup_path(dev)) {
+		ret = stm32_usart_serial_en_wakeup(port, true);
+		if (ret)
+			return ret;
+	}
+
+	/*
+	 * When "no_console_suspend" is enabled, keep the pinctrl default state
+	 * and rely on bootloader stage to restore this state upon resume.
+	 * Otherwise, apply the idle or sleep states depending on wakeup
+	 * capabilities.
+	 */
+	if (console_suspend_enabled || !uart_console(port)) {
+		if (device_may_wakeup(dev) || device_wakeup_path(dev))
+			pinctrl_pm_select_idle_state(dev);
+		else
+			pinctrl_pm_select_sleep_state(dev);
+	}
+
+	return 0;
+}
+
+static int __maybe_unused stm32_usart_serial_resume(struct device *dev)
+{
+	struct uart_port *port = dev_get_drvdata(dev);
+	int ret;
+
+	pinctrl_pm_select_default_state(dev);
+
+	if (device_may_wakeup(dev) || device_wakeup_path(dev)) {
+		ret = stm32_usart_serial_en_wakeup(port, false);
+		if (ret)
+			return ret;
+	}
+
+	return uart_resume_port(&stm32_usart_driver, port);
+}
+
+static int __maybe_unused stm32_usart_runtime_suspend(struct device *dev)
+{
+	struct uart_port *port = dev_get_drvdata(dev);
+	struct stm32_port *stm32port = container_of(port,
+			struct stm32_port, port);
+
+	clk_disable_unprepare(stm32port->clk);
+
+	return 0;
+}
+
+static int __maybe_unused stm32_usart_runtime_resume(struct device *dev)
+{
+	struct uart_port *port = dev_get_drvdata(dev);
+	struct stm32_port *stm32port = container_of(port,
+			struct stm32_port, port);
+
+	return clk_prepare_enable(stm32port->clk);
+}
+
+static const struct dev_pm_ops stm32_serial_pm_ops = {
+	SET_RUNTIME_PM_OPS(stm32_usart_runtime_suspend,
+			   stm32_usart_runtime_resume, NULL)
+	SET_SYSTEM_SLEEP_PM_OPS(stm32_usart_serial_suspend,
+				stm32_usart_serial_resume)
+};
+
+static struct platform_driver stm32_serial_driver = {
+	.probe		= stm32_usart_serial_probe,
+	.remove		= stm32_usart_serial_remove,
+	.driver	= {
+		.name	= DRIVER_NAME,
+		.pm	= &stm32_serial_pm_ops,
+		.of_match_table = of_match_ptr(stm32_match),
+	},
+};
+
+static int __init stm32_usart_init(void)
+{
+	static char banner[] __initdata = "STM32 USART driver initialized";
+	int ret;
+
+	pr_info("%s\n", banner);
+
+	ret = uart_register_driver(&stm32_usart_driver);
+	if (ret)
+		return ret;
+
+	ret = platform_driver_register(&stm32_serial_driver);
+	if (ret)
+		uart_unregister_driver(&stm32_usart_driver);
+
+	return ret;
+}
+
+static void __exit stm32_usart_exit(void)
+{
+	platform_driver_unregister(&stm32_serial_driver);
+	uart_unregister_driver(&stm32_usart_driver);
+}
+
+module_init(stm32_usart_init);
+module_exit(stm32_usart_exit);
+
+MODULE_ALIAS("platform:" DRIVER_NAME);
+MODULE_DESCRIPTION("STMicroelectronics STM32 serial port driver");
+MODULE_LICENSE("GPL v2");