From 480758c596f5d02d795cb5896c5280a6787b72d2 Mon Sep 17 00:00:00 2001
From: Romuald JEANNE <romuald.jeanne@st.com>
Date: Tue, 16 Mar 2021 09:13:39 +0100
Subject: [PATCH 13/22] ARM 5.10.10-stm32mp1-r1 NET-TTY

Signed-off-by: Romuald JEANNE <romuald.jeanne@st.com>
---
 .../net/ethernet/stmicro/stmmac/dwmac-stm32.c |   58 +-
 .../net/ethernet/stmicro/stmmac/stmmac_main.c |   42 +-
 drivers/net/phy/realtek.c                     |   13 +-
 drivers/tty/serial/serial_core.c              |   10 +
 drivers/tty/serial/serial_mctrl_gpio.c        |   38 +
 drivers/tty/serial/serial_mctrl_gpio.h        |   18 +
 drivers/tty/serial/stm32-usart.c              | 1250 +++++++++++------
 drivers/tty/serial/stm32-usart.h              |   28 +-
 include/uapi/linux/serial.h                   |    2 +
 9 files changed, 973 insertions(+), 486 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-stm32.c b/drivers/net/ethernet/stmicro/stmmac/dwmac-stm32.c
index 5d4df4c5254e..ffaa434e075b 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac-stm32.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-stm32.c
@@ -89,7 +89,6 @@ struct stm32_dwmac {
 	int enable_eth_ck;
 	int eth_clk_sel_reg;
 	int eth_ref_clk_sel_reg;
-	int irq_pwr_wakeup;
 	u32 mode_reg;		 /* MAC glue-logic mode register */
 	struct regmap *regmap;
 	u32 speed;
@@ -300,9 +299,7 @@ static int stm32_dwmac_parse_data(struct stm32_dwmac *dwmac,
 static int stm32mp1_parse_data(struct stm32_dwmac *dwmac,
 			       struct device *dev)
 {
-	struct platform_device *pdev = to_platform_device(dev);
 	struct device_node *np = dev->of_node;
-	int err = 0;
 
 	/* Ethernet PHY have no crystal */
 	dwmac->ext_phyclk = of_property_read_bool(np, "st,ext-phyclk");
@@ -334,29 +331,24 @@ static int stm32mp1_parse_data(struct stm32_dwmac *dwmac,
 	if (IS_ERR(dwmac->syscfg_clk))
 		dwmac->syscfg_clk = NULL;
 
-	/* Get IRQ information early to have an ability to ask for deferred
-	 * probe if needed before we went too far with resource allocation.
-	 */
-	dwmac->irq_pwr_wakeup = platform_get_irq_byname_optional(pdev,
-							"stm32_pwr_wakeup");
-	if (dwmac->irq_pwr_wakeup == -EPROBE_DEFER)
-		return -EPROBE_DEFER;
-
-	if (!dwmac->clk_eth_ck && dwmac->irq_pwr_wakeup >= 0) {
-		err = device_init_wakeup(&pdev->dev, true);
-		if (err) {
-			dev_err(&pdev->dev, "Failed to init wake up irq\n");
-			return err;
-		}
-		err = dev_pm_set_dedicated_wake_irq(&pdev->dev,
-						    dwmac->irq_pwr_wakeup);
-		if (err) {
-			dev_err(&pdev->dev, "Failed to set wake up irq\n");
-			device_init_wakeup(&pdev->dev, false);
-		}
-		device_set_wakeup_enable(&pdev->dev, false);
+	return 0;
+}
+
+static int stm32_dwmac_wake_init(struct device *dev,
+				 struct stmmac_resources *stmmac_res)
+{
+	int err;
+
+	device_set_wakeup_capable(dev, true);
+
+	err = dev_pm_set_wake_irq(dev, stmmac_res->wol_irq);
+	if (err) {
+		dev_err(dev, "Failed to set wake up irq\n");
+		device_set_wakeup_capable(dev, false);
+		return err;
 	}
-	return err;
+
+	return 0;
 }
 
 static int stm32_dwmac_probe(struct platform_device *pdev)
@@ -397,6 +389,12 @@ static int stm32_dwmac_probe(struct platform_device *pdev)
 		goto err_remove_config_dt;
 	}
 
+	if (stmmac_res.wol_irq && !dwmac->clk_eth_ck) {
+		ret = stm32_dwmac_wake_init(&pdev->dev, &stmmac_res);
+		if (ret)
+			return ret;
+	}
+
 	plat_dat->bsp_priv = dwmac;
 
 	ret = stm32_dwmac_init(plat_dat);
@@ -422,14 +420,14 @@ static int stm32_dwmac_remove(struct platform_device *pdev)
 	struct net_device *ndev = platform_get_drvdata(pdev);
 	struct stmmac_priv *priv = netdev_priv(ndev);
 	int ret = stmmac_dvr_remove(&pdev->dev);
-	struct stm32_dwmac *dwmac = priv->plat->bsp_priv;
+
+	if (ret)
+		return ret;
 
 	stm32_dwmac_clk_disable(priv->plat->bsp_priv);
 
-	if (dwmac->irq_pwr_wakeup >= 0) {
-		dev_pm_clear_wake_irq(&pdev->dev);
-		device_init_wakeup(&pdev->dev, false);
-	}
+	dev_pm_clear_wake_irq(&pdev->dev);
+	ret = device_init_wakeup(&pdev->dev, false);
 
 	return ret;
 }
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index b3d6d8e3f4de..9c69edc20751 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -1533,18 +1533,18 @@ static void dma_free_tx_skbufs(struct stmmac_priv *priv, u32 queue)
 		stmmac_free_tx_buffer(priv, queue, i);
 }
 
-/**
+/*
  * stmmac_free_tx_skbufs - free TX skb buffers
  * @priv: private structure
  */
-static void stmmac_free_tx_skbufs(struct stmmac_priv *priv)
+/*static void stmmac_free_tx_skbufs(struct stmmac_priv *priv)
 {
-	u32 tx_queue_cnt = priv->plat->tx_queues_to_use;
-	u32 queue;
+        u32 tx_queue_cnt = priv->plat->tx_queues_to_use;
+        u32 queue;
 
-	for (queue = 0; queue < tx_queue_cnt; queue++)
-		dma_free_tx_skbufs(priv, queue);
-}
+        for (queue = 0; queue < tx_queue_cnt; queue++)
+                dma_free_tx_skbufs(priv, queue);
+}*/
 
 /**
  * free_dma_rx_desc_resources - free RX dma desc resources
@@ -5289,8 +5289,25 @@ int stmmac_resume(struct device *dev)
 
 	stmmac_reset_queues_param(priv);
 
-	stmmac_free_tx_skbufs(priv);
-	stmmac_clear_descriptors(priv);
+	/* Stop TX/RX DMA and clear the descriptors */
+	stmmac_stop_all_dma(priv);
+
+	/* Release and free the Rx/Tx resources */
+	free_dma_desc_resources(priv);
+
+	ret = alloc_dma_desc_resources(priv);
+	if (ret < 0) {
+		netdev_err(priv->dev, "%s: DMA descriptors allocation failed\n",
+			   __func__);
+		goto dma_desc_error;
+	}
+
+	ret = init_dma_desc_rings(ndev, GFP_KERNEL);
+	if (ret < 0) {
+		netdev_err(priv->dev, "%s: DMA descriptors initialization failed\n",
+			   __func__);
+		goto init_error;
+	}
 
 	stmmac_hw_setup(ndev, false);
 	stmmac_init_coalesce(priv);
@@ -5308,6 +5325,13 @@ int stmmac_resume(struct device *dev)
 	netif_device_attach(ndev);
 
 	return 0;
+init_error:
+	free_dma_desc_resources(priv);
+dma_desc_error:
+	if (ndev->phydev)
+		phy_disconnect(ndev->phydev);
+
+	return -1;
 }
 EXPORT_SYMBOL_GPL(stmmac_resume);
 
diff --git a/drivers/net/phy/realtek.c b/drivers/net/phy/realtek.c
index 575580d3ffe0..a200019180de 100644
--- a/drivers/net/phy/realtek.c
+++ b/drivers/net/phy/realtek.c
@@ -26,16 +26,11 @@
 #define RTL821x_EXT_PAGE_SELECT			0x1e
 #define RTL821x_PAGE_SELECT			0x1f
 
-#define RTL8211F_PHYCR1				0x18
 #define RTL8211F_INSR				0x1d
 
 #define RTL8211F_TX_DELAY			BIT(8)
 #define RTL8211F_RX_DELAY			BIT(3)
 
-#define RTL8211F_ALDPS_PLL_OFF			BIT(1)
-#define RTL8211F_ALDPS_ENABLE			BIT(2)
-#define RTL8211F_ALDPS_XTAL_OFF			BIT(12)
-
 #define RTL8211E_CTRL_DELAY			BIT(13)
 #define RTL8211E_TX_DELAY			BIT(12)
 #define RTL8211E_RX_DELAY			BIT(11)
@@ -182,11 +177,12 @@ static int rtl8211f_config_init(struct phy_device *phydev)
 {
 	struct device *dev = &phydev->mdio.dev;
 	u16 val_txdly, val_rxdly;
-	u16 val;
 	int ret;
 
-	val = RTL8211F_ALDPS_ENABLE | RTL8211F_ALDPS_PLL_OFF | RTL8211F_ALDPS_XTAL_OFF;
-	phy_modify_paged_changed(phydev, 0xa43, RTL8211F_PHYCR1, val, val);
+	/* Set green LED for Link, yellow LED for Active */
+	phy_write(phydev, RTL821x_PAGE_SELECT, 0xd04);
+	phy_write(phydev, 0x10, 0x617f);
+	phy_write(phydev, RTL821x_PAGE_SELECT, 0x0);
 
 	switch (phydev->interface) {
 	case PHY_INTERFACE_MODE_RGMII:
@@ -621,6 +617,7 @@ static struct phy_driver realtek_drvs[] = {
 		PHY_ID_MATCH_EXACT(0x001cc916),
 		.name		= "RTL8211F Gigabit Ethernet",
 		.config_init	= &rtl8211f_config_init,
+		.read_status	= rtlgen_read_status,
 		.ack_interrupt	= &rtl8211f_ack_interrupt,
 		.config_intr	= &rtl8211f_config_intr,
 		.suspend	= genphy_suspend,
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 828f9ad1be49..c8ed6756c255 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -3224,6 +3224,16 @@ int uart_get_rs485_mode(struct uart_port *port)
 	u32 rs485_delay[2];
 	int ret;
 
+	ret = device_property_read_u32_array(dev, "rs485-rts-delay-ns",
+					     rs485_delay, 2);
+	if (!ret) {
+		rs485conf->delay_rts_before_send_ns = rs485_delay[0];
+		rs485conf->delay_rts_after_send_ns = rs485_delay[1];
+	} else {
+		rs485conf->delay_rts_before_send_ns = 0;
+		rs485conf->delay_rts_after_send_ns = 0;
+	}
+
 	ret = device_property_read_u32_array(dev, "rs485-rts-delay",
 					     rs485_delay, 2);
 	if (!ret) {
diff --git a/drivers/tty/serial/serial_mctrl_gpio.c b/drivers/tty/serial/serial_mctrl_gpio.c
index fb4781292d40..1fc2f704769e 100644
--- a/drivers/tty/serial/serial_mctrl_gpio.c
+++ b/drivers/tty/serial/serial_mctrl_gpio.c
@@ -299,4 +299,42 @@ void mctrl_gpio_disable_ms(struct mctrl_gpios *gpios)
 }
 EXPORT_SYMBOL_GPL(mctrl_gpio_disable_ms);
 
+void mctrl_gpio_enable_irq_wake(struct mctrl_gpios *gpios)
+{
+	enum mctrl_gpio_idx i;
+
+	if (!gpios)
+		return;
+
+	if (!gpios->mctrl_on)
+		return;
+
+	for (i = 0; i < UART_GPIO_MAX; ++i) {
+		if (!gpios->irq[i])
+			continue;
+
+		enable_irq_wake(gpios->irq[i]);
+	}
+}
+EXPORT_SYMBOL_GPL(mctrl_gpio_enable_irq_wake);
+
+void mctrl_gpio_disable_irq_wake(struct mctrl_gpios *gpios)
+{
+	enum mctrl_gpio_idx i;
+
+	if (!gpios)
+		return;
+
+	if (!gpios->mctrl_on)
+		return;
+
+	for (i = 0; i < UART_GPIO_MAX; ++i) {
+		if (!gpios->irq[i])
+			continue;
+
+		disable_irq_wake(gpios->irq[i]);
+	}
+}
+EXPORT_SYMBOL_GPL(mctrl_gpio_disable_irq_wake);
+
 MODULE_LICENSE("GPL");
diff --git a/drivers/tty/serial/serial_mctrl_gpio.h b/drivers/tty/serial/serial_mctrl_gpio.h
index b134a0ffc894..fc76910fb105 100644
--- a/drivers/tty/serial/serial_mctrl_gpio.h
+++ b/drivers/tty/serial/serial_mctrl_gpio.h
@@ -91,6 +91,16 @@ void mctrl_gpio_enable_ms(struct mctrl_gpios *gpios);
  */
 void mctrl_gpio_disable_ms(struct mctrl_gpios *gpios);
 
+/*
+ * Enable gpio wakeup interrupts to enable wake up source.
+ */
+void mctrl_gpio_enable_irq_wake(struct mctrl_gpios *gpios);
+
+/*
+ * Disable gpio wakeup interrupts to enable wake up source.
+ */
+void mctrl_gpio_disable_irq_wake(struct mctrl_gpios *gpios);
+
 #else /* GPIOLIB */
 
 static inline
@@ -142,6 +152,14 @@ static inline void mctrl_gpio_disable_ms(struct mctrl_gpios *gpios)
 {
 }
 
+static inline void mctrl_gpio_enable_irq_wake(struct mctrl_gpios *gpios)
+{
+}
+
+static inline void mctrl_gpio_disable_irq_wake(struct mctrl_gpios *gpios)
+{
+}
+
 #endif /* GPIOLIB */
 
 #endif
diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c
index ee6c7762d355..5694e78646eb 100644
--- a/drivers/tty/serial/stm32-usart.c
+++ b/drivers/tty/serial/stm32-usart.c
@@ -4,6 +4,7 @@
  * Copyright (C) STMicroelectronics SA 2017
  * Authors:  Maxime Coquelin <mcoquelin.stm32@gmail.com>
  *	     Gerald Baeza <gerald.baeza@st.com>
+ *	     Erwan Le Ray <erwan.leray@st.com>
  *
  * Inspired by st-asc.c from STMicroelectronics (c)
  */
@@ -34,15 +35,15 @@
 #include "serial_mctrl_gpio.h"
 #include "stm32-usart.h"
 
-static void stm32_stop_tx(struct uart_port *port);
-static void stm32_transmit_chars(struct uart_port *port);
+static void stm32_usart_stop_tx(struct uart_port *port);
+static void stm32_usart_transmit_chars(struct uart_port *port);
 
 static inline struct stm32_port *to_stm32_port(struct uart_port *port)
 {
 	return container_of(port, struct stm32_port, port);
 }
 
-static void stm32_set_bits(struct uart_port *port, u32 reg, u32 bits)
+static void stm32_usart_set_bits(struct uart_port *port, u32 reg, u32 bits)
 {
 	u32 val;
 
@@ -51,7 +52,7 @@ static void stm32_set_bits(struct uart_port *port, u32 reg, u32 bits)
 	writel_relaxed(val, port->membase + reg);
 }
 
-static void stm32_clr_bits(struct uart_port *port, u32 reg, u32 bits)
+static void stm32_usart_clr_bits(struct uart_port *port, u32 reg, u32 bits)
 {
 	u32 val;
 
@@ -60,43 +61,70 @@ static void stm32_clr_bits(struct uart_port *port, u32 reg, u32 bits)
 	writel_relaxed(val, port->membase + reg);
 }
 
-static void stm32_config_reg_rs485(u32 *cr1, u32 *cr3, u32 delay_ADE,
-				   u32 delay_DDE, u32 baud)
+static u32 stm32_usart_config_delay_rs485(u32 *cr1, u32 delay, u32 baud,
+					  bool over8, u32 rs485_deat_dedt_max,
+					  struct serial_rs485 *rs485conf)
 {
-	u32 rs485_deat_dedt;
+	u64 tmp;
+
+	/*
+	 * Compute (de)assertion time by using the delay (in ns), the baud rate
+	 * (in bits/s) and the oversampling (in 1/8 or 1/16 bit)
+	 */
+	tmp = (u64)delay * (u64)baud * 8ULL;
+
+	/* Handle oversampling 16 */
+	if (!over8)
+		tmp = tmp * 2ULL;
+
+	tmp = DIV_ROUND_CLOSEST_ULL(tmp, NSEC_PER_SEC);
+
+	/* Set delay to max value if result is higher than max value */
+	tmp = tmp > rs485_deat_dedt_max ? rs485_deat_dedt_max : tmp;
+
+	return tmp;
+}
+
+static void stm32_usart_config_reg_rs485(u32 *cr1, u32 *cr3,  u32 baud,
+					 struct serial_rs485 *rs485conf)
+{
+	u32 delay_ADE, delay_DDE, rs485_deat_dedt;
 	u32 rs485_deat_dedt_max = (USART_CR1_DEAT_MASK >> USART_CR1_DEAT_SHIFT);
 	bool over8;
+	u32 tmp;
+
+	/*
+	 * Assertion and deassertion delays (in ns) are computed by the
+	 * selection of rs485-rts-delay-ns (in ns) or rs485-rts-delay (in ms)
+	 * provided by device tree
+	 */
+	if (rs485conf->delay_rts_before_send_ns != 0 ||
+	    rs485conf->delay_rts_after_send_ns != 0) {
+		delay_ADE = rs485conf->delay_rts_before_send_ns;
+		delay_DDE = rs485conf->delay_rts_after_send_ns;
+	} else {
+		delay_ADE = rs485conf->delay_rts_before_send * NSEC_PER_MSEC;
+		delay_DDE = rs485conf->delay_rts_after_send * NSEC_PER_MSEC;
+	}
 
 	*cr3 |= USART_CR3_DEM;
 	over8 = *cr1 & USART_CR1_OVER8;
 
-	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;
+	/* Assertion time */
+	tmp = stm32_usart_config_delay_rs485(cr1, delay_ADE, baud, over8,
+					     rs485_deat_dedt_max, rs485conf);
+	rs485_deat_dedt = (tmp << 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;
+	/* Deassertion time */
+	tmp = stm32_usart_config_delay_rs485(cr1, delay_DDE, baud, over8,
+					     rs485_deat_dedt_max, rs485conf);
+	rs485_deat_dedt = (tmp << USART_CR1_DEDT_SHIFT) & USART_CR1_DEDT_MASK;
 	*cr1 |= rs485_deat_dedt;
 }
 
-static int stm32_config_rs485(struct uart_port *port,
-			      struct serial_rs485 *rs485conf)
+static int stm32_usart_config_rs485(struct uart_port *port,
+				    struct serial_rs485 *rs485conf)
 {
 	struct stm32_port *stm32_port = to_stm32_port(port);
 	struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
@@ -104,7 +132,7 @@ static int stm32_config_rs485(struct uart_port *port,
 	u32 usartdiv, baud, cr1, cr3;
 	bool over8;
 
-	stm32_clr_bits(port, ofs->cr1, BIT(cfg->uart_enable_bit));
+	stm32_usart_clr_bits(port, ofs->cr1, BIT(cfg->uart_enable_bit));
 
 	port->rs485 = *rs485conf;
 
@@ -122,9 +150,7 @@ static int stm32_config_rs485(struct uart_port *port,
 				   << USART_BRR_04_R_SHIFT;
 
 		baud = DIV_ROUND_CLOSEST(port->uartclk, usartdiv);
-		stm32_config_reg_rs485(&cr1, &cr3,
-				       rs485conf->delay_rts_before_send,
-				       rs485conf->delay_rts_after_send, baud);
+		stm32_usart_config_reg_rs485(&cr1, &cr3, baud, rs485conf);
 
 		if (rs485conf->flags & SER_RS485_RTS_ON_SEND) {
 			cr3 &= ~USART_CR3_DEP;
@@ -137,18 +163,19 @@ static int stm32_config_rs485(struct uart_port *port,
 		writel_relaxed(cr3, port->membase + ofs->cr3);
 		writel_relaxed(cr1, port->membase + ofs->cr1);
 	} else {
-		stm32_clr_bits(port, ofs->cr3, USART_CR3_DEM | USART_CR3_DEP);
-		stm32_clr_bits(port, ofs->cr1,
-			       USART_CR1_DEDT_MASK | USART_CR1_DEAT_MASK);
+		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_set_bits(port, ofs->cr1, BIT(cfg->uart_enable_bit));
+	stm32_usart_set_bits(port, ofs->cr1, BIT(cfg->uart_enable_bit));
 
 	return 0;
 }
 
-static int stm32_init_rs485(struct uart_port *port,
-			    struct platform_device *pdev)
+static int stm32_usart_init_rs485(struct uart_port *port,
+				  struct platform_device *pdev)
 {
 	struct serial_rs485 *rs485conf = &port->rs485;
 
@@ -162,64 +189,67 @@ static int stm32_init_rs485(struct uart_port *port,
 	return uart_get_rs485_mode(port);
 }
 
-static int stm32_pending_rx(struct uart_port *port, u32 *sr, int *last_res,
-			    bool threaded)
+static bool stm32_usart_rx_dma_enabled(struct uart_port *port)
+{
+	struct stm32_port *stm32_port = to_stm32_port(port);
+	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);
 	struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
-	enum dma_status status;
-	struct dma_tx_state state;
 
 	*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;
 
-	if (threaded && stm32_port->rx_ch) {
-		status = dmaengine_tx_status(stm32_port->rx_ch,
-					     stm32_port->rx_ch->cookie,
-					     &state);
-		if ((status == DMA_IN_PROGRESS) &&
-		    (*last_res != state.residue))
-			return 1;
-		else
-			return 0;
-	} else if (*sr & USART_SR_RXNE) {
-		return 1;
+		/* Handle only RX data errors when using DMA */
+		if (*sr & USART_SR_ERR_MASK)
+			return true;
 	}
-	return 0;
+
+	return false;
 }
 
-static unsigned long stm32_get_char(struct uart_port *port, u32 *sr,
-				    int *last_res)
+static unsigned long stm32_usart_get_char_pio(struct uart_port *port)
 {
 	struct stm32_port *stm32_port = to_stm32_port(port);
 	struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
 	unsigned long c;
 
-	if (stm32_port->rx_ch) {
-		c = stm32_port->rx_buf[RX_BUF_L - (*last_res)--];
-		if ((*last_res) == 0)
-			*last_res = RX_BUF_L;
-	} else {
-		c = readl_relaxed(port->membase + ofs->rdr);
-		/* apply RDR data mask */
-		c &= stm32_port->rdr_mask;
-	}
+	c = readl_relaxed(port->membase + ofs->rdr);
+	/* Apply RDR data mask */
+	c &= stm32_port->rdr_mask;
 
 	return c;
 }
 
-static void stm32_receive_chars(struct uart_port *port, bool threaded)
+static unsigned int stm32_usart_receive_chars_pio(struct uart_port *port)
 {
-	struct tty_port *tport = &port->state->port;
 	struct stm32_port *stm32_port = to_stm32_port(port);
 	struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
 	unsigned long c;
+	unsigned int size = 0;
 	u32 sr;
 	char flag;
 
-	if (irqd_is_wakeup_set(irq_get_irq_data(port->irq)))
-		pm_wakeup_event(tport->tty->dev, 0);
-
-	while (stm32_pending_rx(port, &sr, &stm32_port->last_res, threaded)) {
+	while (stm32_usart_pending_rx_pio(port, &sr)) {
 		sr |= USART_SR_DUMMY_RX;
 		flag = TTY_NORMAL;
 
@@ -238,8 +268,9 @@ static void stm32_receive_chars(struct uart_port *port, bool threaded)
 			writel_relaxed(sr & USART_SR_ERR_MASK,
 				       port->membase + ofs->icr);
 
-		c = stm32_get_char(port, &sr, &stm32_port->last_res);
+		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++;
@@ -273,25 +304,140 @@ static void stm32_receive_chars(struct uart_port *port, bool threaded)
 		uart_insert_char(port, sr, USART_SR_ORE, c, flag);
 	}
 
-	spin_unlock(&port->lock);
-	tty_flip_buffer_push(tport);
-	spin_lock(&port->lock);
+	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;
+
+	dma_start = stm32_port->rx_buf + (RX_BUF_L - stm32_port->last_res);
+	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 void stm32_usart_receive_chars(struct uart_port *port,
+				      bool force_dma_flush)
+{
+	struct tty_port *tport = &port->state->port;
+	struct stm32_port *stm32_port = to_stm32_port(port);
+	struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
+	enum dma_status rx_dma_status;
+	u32 sr;
+	unsigned int size;
+
+	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);
+	}
+
+	if (size)
+		tty_flip_buffer_push(tport);
+}
+
+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 have 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)
+{
+	struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
+
+	return !!(readl_relaxed(stm32_port->port.membase + ofs->cr3)
+				& USART_CR3_DMAT);
 }
 
-static void stm32_tx_dma_complete(void *arg)
+static void stm32_usart_tx_dma_complete(void *arg)
 {
 	struct uart_port *port = arg;
 	struct stm32_port *stm32port = to_stm32_port(port);
 	struct stm32_usart_offsets *ofs = &stm32port->info->ofs;
+	unsigned long flags;
 
-	stm32_clr_bits(port, ofs->cr3, USART_CR3_DMAT);
-	stm32port->tx_dma_busy = false;
+	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 */
-	stm32_transmit_chars(port);
+	spin_lock_irqsave(&port->lock, flags);
+	stm32_usart_transmit_chars(port);
+	spin_unlock_irqrestore(&port->lock, flags);
 }
 
-static void stm32_tx_interrupt_enable(struct uart_port *port)
+static void stm32_usart_tx_interrupt_enable(struct uart_port *port)
 {
 	struct stm32_port *stm32_port = to_stm32_port(port);
 	struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
@@ -300,33 +446,41 @@ static void stm32_tx_interrupt_enable(struct uart_port *port)
 	 * Enables TX FIFO threashold irq when FIFO is enabled,
 	 * or TX empty irq when FIFO is disabled
 	 */
-	if (stm32_port->fifoen)
-		stm32_set_bits(port, ofs->cr3, USART_CR3_TXFTIE);
+	if (stm32_port->fifoen && stm32_port->txftcfg >= 0)
+		stm32_usart_set_bits(port, ofs->cr3, USART_CR3_TXFTIE);
 	else
-		stm32_set_bits(port, ofs->cr1, USART_CR1_TXEIE);
+		stm32_usart_set_bits(port, ofs->cr1, USART_CR1_TXEIE);
 }
 
-static void stm32_tx_interrupt_disable(struct uart_port *port)
+static void stm32_usart_rx_dma_complete(void *arg)
+{
+	struct uart_port *port = arg;
+	unsigned long flags;
+
+	spin_lock_irqsave(&port->lock, flags);
+	stm32_usart_receive_chars(port, false);
+	spin_unlock_irqrestore(&port->lock, flags);
+}
+
+static void stm32_usart_tx_interrupt_disable(struct uart_port *port)
 {
 	struct stm32_port *stm32_port = to_stm32_port(port);
 	struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
 
-	if (stm32_port->fifoen)
-		stm32_clr_bits(port, ofs->cr3, USART_CR3_TXFTIE);
+	if (stm32_port->fifoen && stm32_port->txftcfg >= 0)
+		stm32_usart_clr_bits(port, ofs->cr3, USART_CR3_TXFTIE);
 	else
-		stm32_clr_bits(port, ofs->cr1, USART_CR1_TXEIE);
+		stm32_usart_clr_bits(port, ofs->cr1, USART_CR1_TXEIE);
 }
 
-static void stm32_transmit_chars_pio(struct uart_port *port)
+static void stm32_usart_transmit_chars_pio(struct uart_port *port)
 {
 	struct stm32_port *stm32_port = to_stm32_port(port);
 	struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
 	struct circ_buf *xmit = &port->state->xmit;
 
-	if (stm32_port->tx_dma_busy) {
-		stm32_clr_bits(port, ofs->cr3, USART_CR3_DMAT);
-		stm32_port->tx_dma_busy = false;
-	}
+	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 */
@@ -339,24 +493,25 @@ static void stm32_transmit_chars_pio(struct uart_port *port)
 
 	/* rely on TXE irq (mask or unmask) for sending remaining data */
 	if (uart_circ_empty(xmit))
-		stm32_tx_interrupt_disable(port);
+		stm32_usart_tx_interrupt_disable(port);
 	else
-		stm32_tx_interrupt_enable(port);
+		stm32_usart_tx_interrupt_enable(port);
 }
 
-static void stm32_transmit_chars_dma(struct uart_port *port)
+static void stm32_usart_transmit_chars_dma(struct uart_port *port)
 {
 	struct stm32_port *stm32port = to_stm32_port(port);
 	struct stm32_usart_offsets *ofs = &stm32port->info->ofs;
 	struct circ_buf *xmit = &port->state->xmit;
 	struct dma_async_tx_descriptor *desc = NULL;
 	dma_cookie_t cookie;
-	unsigned int count, i;
+	unsigned int count, i, ret;
 
-	if (stm32port->tx_dma_busy)
+	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;
-
-	stm32port->tx_dma_busy = true;
+	}
 
 	count = uart_circ_chars_pending(xmit);
 
@@ -384,136 +539,181 @@ static void stm32_transmit_chars_dma(struct uart_port *port)
 					   DMA_MEM_TO_DEV,
 					   DMA_PREP_INTERRUPT);
 
-	if (!desc) {
-		for (i = count; i > 0; i--)
-			stm32_transmit_chars_pio(port);
-		return;
-	}
+	if (!desc)
+		goto fallback_err;
+
+	/*
+	 * Take "tx_dma_busy" flag. This flag will be release when
+	 * dmaengine_terminate_async will be called. This flag helps
+	 * transmit_chars_dma to doesn't start another dma transaction
+	 * if the callback of the previous is not called.
+	 */
+	stm32port->tx_dma_busy = true;
 
-	desc->callback = stm32_tx_dma_complete;
+	desc->callback = stm32_usart_tx_dma_complete;
 	desc->callback_param = port;
 
 	/* Push current DMA TX transaction in the pending queue */
 	cookie = dmaengine_submit(desc);
+	ret = dma_submit_error(cookie);
+	if (ret) {
+		/* 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_set_bits(port, ofs->cr3, USART_CR3_DMAT);
+	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:
+	for (i = count; i > 0; i--)
+		stm32_usart_transmit_chars_pio(port);
 }
 
-static void stm32_transmit_chars(struct uart_port *port)
+static void stm32_usart_transmit_chars(struct uart_port *port)
 {
 	struct stm32_port *stm32_port = to_stm32_port(port);
 	struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
 	struct circ_buf *xmit = &port->state->xmit;
+	u32 isr;
+	int ret;
 
 	if (port->x_char) {
-		if (stm32_port->tx_dma_busy)
-			stm32_clr_bits(port, ofs->cr3, USART_CR3_DMAT);
+		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_port->tx_dma_busy)
-			stm32_set_bits(port, ofs->cr3, USART_CR3_DMAT);
+		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_tx_interrupt_disable(port);
+		stm32_usart_tx_interrupt_disable(port);
 		return;
 	}
 
 	if (ofs->icr == UNDEF_REG)
-		stm32_clr_bits(port, ofs->isr, USART_SR_TC);
+		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_transmit_chars_dma(port);
+		stm32_usart_transmit_chars_dma(port);
 	else
-		stm32_transmit_chars_pio(port);
+		stm32_usart_transmit_chars_pio(port);
 
 	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
 		uart_write_wakeup(port);
 
 	if (uart_circ_empty(xmit))
-		stm32_tx_interrupt_disable(port);
+		stm32_usart_tx_interrupt_disable(port);
 }
 
-static irqreturn_t stm32_interrupt(int irq, void *ptr)
+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);
 	struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
 	u32 sr;
 
-	spin_lock(&port->lock);
-
 	sr = readl_relaxed(port->membase + ofs->isr);
 
 	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))
+	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);
+	}
 
-	if ((sr & USART_SR_RXNE) && !(stm32_port->rx_ch))
-		stm32_receive_chars(port, false);
-
-	if ((sr & USART_SR_TXE) && !(stm32_port->tx_ch))
-		stm32_transmit_chars(port);
+	/*
+	 * 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 &&
+	    (((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);
+		stm32_usart_receive_chars(port, false);
+		spin_unlock(&port->lock);
+	}
 
-	spin_unlock(&port->lock);
+	if ((sr & USART_SR_TXE) && !(stm32_port->tx_ch)) {
+		spin_lock(&port->lock);
+		stm32_usart_transmit_chars(port);
+		spin_unlock(&port->lock);
+	}
 
-	if (stm32_port->rx_ch)
+	if (stm32_usart_rx_dma_enabled(port))
 		return IRQ_WAKE_THREAD;
 	else
 		return IRQ_HANDLED;
 }
 
-static irqreturn_t stm32_threaded_interrupt(int irq, void *ptr)
+static irqreturn_t stm32_usart_threaded_interrupt(int irq, void *ptr)
 {
 	struct uart_port *port = ptr;
-	struct stm32_port *stm32_port = to_stm32_port(port);
-
-	spin_lock(&port->lock);
-
-	if (stm32_port->rx_ch)
-		stm32_receive_chars(port, true);
+	unsigned long flags;
 
-	spin_unlock(&port->lock);
+	spin_lock_irqsave(&port->lock, flags);
+	/* Receiver timeout irq for DMA RX */
+	stm32_usart_receive_chars(port, false);
+	spin_unlock_irqrestore(&port->lock, flags);
 
 	return IRQ_HANDLED;
 }
 
-static unsigned int stm32_tx_empty(struct uart_port *port)
+static unsigned int stm32_usart_tx_empty(struct uart_port *port)
 {
 	struct stm32_port *stm32_port = to_stm32_port(port);
 	struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
 
-	return readl_relaxed(port->membase + ofs->isr) & USART_SR_TXE;
+	if (readl_relaxed(port->membase + ofs->isr) & USART_SR_TC)
+		return TIOCSER_TEMT;
+
+	return 0;
 }
 
-static void stm32_set_mctrl(struct uart_port *port, unsigned int mctrl)
+static void stm32_usart_set_mctrl(struct uart_port *port, unsigned int mctrl)
 {
 	struct stm32_port *stm32_port = to_stm32_port(port);
 	struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
 
 	if ((mctrl & TIOCM_RTS) && (port->status & UPSTAT_AUTORTS))
-		stm32_set_bits(port, ofs->cr3, USART_CR3_RTSE);
+		stm32_usart_set_bits(port, ofs->cr3, USART_CR3_RTSE);
 	else
-		stm32_clr_bits(port, ofs->cr3, USART_CR3_RTSE);
+		stm32_usart_clr_bits(port, ofs->cr3, USART_CR3_RTSE);
 
 	mctrl_gpio_set(stm32_port->gpios, mctrl);
 }
 
-static unsigned int stm32_get_mctrl(struct uart_port *port)
+static unsigned int stm32_usart_get_mctrl(struct uart_port *port)
 {
 	struct stm32_port *stm32_port = to_stm32_port(port);
 	unsigned int ret;
@@ -524,23 +724,27 @@ static unsigned int stm32_get_mctrl(struct uart_port *port)
 	return mctrl_gpio_get(stm32_port->gpios, &ret);
 }
 
-static void stm32_enable_ms(struct uart_port *port)
+static void stm32_usart_enable_ms(struct uart_port *port)
 {
 	mctrl_gpio_enable_ms(to_stm32_port(port)->gpios);
 }
 
-static void stm32_disable_ms(struct uart_port *port)
+static void stm32_usart_disable_ms(struct uart_port *port)
 {
 	mctrl_gpio_disable_ms(to_stm32_port(port)->gpios);
 }
 
 /* Transmit stop */
-static void stm32_stop_tx(struct uart_port *port)
+static void stm32_usart_stop_tx(struct uart_port *port)
 {
 	struct stm32_port *stm32_port = to_stm32_port(port);
 	struct serial_rs485 *rs485conf = &port->rs485;
+	struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
 
-	stm32_tx_interrupt_disable(port);
+	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);
 
 	if (rs485conf->flags & SER_RS485_ENABLED) {
 		if (rs485conf->flags & SER_RS485_RTS_ON_SEND) {
@@ -554,13 +758,13 @@ static void stm32_stop_tx(struct uart_port *port)
 }
 
 /* There are probably characters waiting to be transmitted. */
-static void stm32_start_tx(struct uart_port *port)
+static void stm32_usart_start_tx(struct uart_port *port)
 {
 	struct stm32_port *stm32_port = to_stm32_port(port);
 	struct serial_rs485 *rs485conf = &port->rs485;
 	struct circ_buf *xmit = &port->state->xmit;
 
-	if (uart_circ_empty(xmit))
+	if (uart_circ_empty(xmit) && !port->x_char)
 		return;
 
 	if (rs485conf->flags & SER_RS485_ENABLED) {
@@ -573,93 +777,166 @@ static void stm32_start_tx(struct uart_port *port)
 		}
 	}
 
-	stm32_transmit_chars(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);
+	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_throttle(struct uart_port *port)
+static void stm32_usart_throttle(struct uart_port *port)
 {
 	struct stm32_port *stm32_port = to_stm32_port(port);
 	struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
 	unsigned long flags;
 
 	spin_lock_irqsave(&port->lock, flags);
-	stm32_clr_bits(port, ofs->cr1, stm32_port->cr1_irq);
+
+	/*
+	 * 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_clr_bits(port, ofs->cr3, 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_unthrottle(struct uart_port *port)
+static void stm32_usart_unthrottle(struct uart_port *port)
 {
 	struct stm32_port *stm32_port = to_stm32_port(port);
 	struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
 	unsigned long flags;
 
 	spin_lock_irqsave(&port->lock, flags);
-	stm32_set_bits(port, ofs->cr1, stm32_port->cr1_irq);
+	stm32_usart_set_bits(port, ofs->cr1, stm32_port->cr1_irq);
 	if (stm32_port->cr3_irq)
-		stm32_set_bits(port, ofs->cr3, 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_stop_rx(struct uart_port *port)
+static void stm32_usart_stop_rx(struct uart_port *port)
 {
 	struct stm32_port *stm32_port = to_stm32_port(port);
 	struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
 
-	stm32_clr_bits(port, ofs->cr1, stm32_port->cr1_irq);
-	if (stm32_port->cr3_irq)
-		stm32_clr_bits(port, ofs->cr3, stm32_port->cr3_irq);
+	/* 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_break_ctl(struct uart_port *port, int break_state)
+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);
+	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_startup(struct uart_port *port)
+static int stm32_usart_startup(struct uart_port *port)
 {
 	struct stm32_port *stm32_port = to_stm32_port(port);
 	struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
+	struct stm32_usart_config *cfg = &stm32_port->info->cfg;
 	const char *name = to_platform_device(port->dev)->name;
 	u32 val;
 	int ret;
 
-	ret = request_threaded_irq(port->irq, stm32_interrupt,
-				   stm32_threaded_interrupt,
+	ret = request_threaded_irq(port->irq, stm32_usart_interrupt,
+				   stm32_usart_threaded_interrupt,
 				   IRQF_NO_SUSPEND, name, port);
 	if (ret)
 		return ret;
 
 	/* RX FIFO Flush */
 	if (ofs->rqr != UNDEF_REG)
-		stm32_set_bits(port, ofs->rqr, USART_RQR_RXFRQ);
+		writel_relaxed(USART_RQR_RXFRQ, port->membase + ofs->rqr);
 
-	/* Tx and RX FIFO configuration */
-	if (stm32_port->fifoen) {
-		val = readl_relaxed(port->membase + ofs->cr3);
-		val &= ~(USART_CR3_TXFTCFG_MASK | USART_CR3_RXFTCFG_MASK);
-		val |= USART_CR3_TXFTCFG_HALF << USART_CR3_TXFTCFG_SHIFT;
-		val |= USART_CR3_RXFTCFG_HALF << USART_CR3_RXFTCFG_SHIFT;
-		writel_relaxed(val, port->membase + ofs->cr3);
+	if (stm32_port->rx_ch) {
+		ret = stm32_usart_start_rx_dma_cyclic(port);
+		if (ret) {
+			free_irq(port->irq, port);
+			return ret;
+		}
 	}
 
-	/* RX FIFO enabling */
-	val = stm32_port->cr1_irq | USART_CR1_RE;
-	if (stm32_port->fifoen)
-		val |= USART_CR1_FIFOEN;
-	stm32_set_bits(port, ofs->cr1, val);
+	/* 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_shutdown(struct uart_port *port)
+static void stm32_usart_shutdown(struct uart_port *port)
 {
 	struct stm32_port *stm32_port = to_stm32_port(port);
 	struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
@@ -667,8 +944,14 @@ static void stm32_shutdown(struct uart_port *port)
 	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_disable_ms(port);
+	stm32_usart_disable_ms(port);
 
 	val = USART_CR1_TXEIE | USART_CR1_TE;
 	val |= stm32_port->cr1_irq | USART_CR1_RE;
@@ -680,15 +963,25 @@ static void stm32_shutdown(struct uart_port *port)
 					 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 complete not set\n");
+		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_clr_bits(port, ofs->cr1, val);
+	stm32_usart_clr_bits(port, ofs->cr1, val);
 
 	free_irq(port->irq, port);
 }
 
-static unsigned int stm32_get_databits(struct ktermios *termios)
+static unsigned int stm32_usart_get_databits(struct ktermios *termios)
 {
 	unsigned int bits;
 
@@ -718,8 +1011,9 @@ static unsigned int stm32_get_databits(struct ktermios *termios)
 	return bits;
 }
 
-static void stm32_set_termios(struct uart_port *port, struct ktermios *termios,
-			    struct ktermios *old)
+static void stm32_usart_set_termios(struct uart_port *port,
+				    struct ktermios *termios,
+				    struct ktermios *old)
 {
 	struct stm32_port *stm32_port = to_stm32_port(port);
 	struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
@@ -728,8 +1022,9 @@ static void stm32_set_termios(struct uart_port *port, struct ktermios *termios,
 	unsigned int baud, bits;
 	u32 usartdiv, mantissa, fraction, oversampling;
 	tcflag_t cflag = termios->c_cflag;
-	u32 cr1, cr2, cr3;
+	u32 cr1, cr2, cr3, isr;
 	unsigned long flags;
+	int ret;
 
 	if (!stm32_port->hw_flow_control)
 		cflag &= ~CRTSCTS;
@@ -738,26 +1033,42 @@ static void stm32_set_termios(struct uart_port *port, struct ktermios *termios,
 
 	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)
-		stm32_set_bits(port, ofs->rqr,
-			       USART_RQR_TXFRQ | USART_RQR_RXFRQ);
+		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 = 0;
+
+	/* Tx and RX FIFO configuration */
 	cr3 = readl_relaxed(port->membase + ofs->cr3);
-	cr3 &= USART_CR3_TXFTIE | USART_CR3_RXFTCFG_MASK | USART_CR3_RXFTIE
-		| USART_CR3_TXFTCFG_MASK;
+	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 = stm32_get_databits(termios);
+	bits = stm32_usart_get_databits(termios);
 	stm32_port->rdr_mask = (BIT(bits) - 1);
 
 	if (cflag & PARENB) {
@@ -781,7 +1092,8 @@ static void stm32_set_termios(struct uart_port *port, struct ktermios *termios,
 			, bits);
 
 	if (ofs->rtor != UNDEF_REG && (stm32_port->rx_ch ||
-				       stm32_port->fifoen)) {
+				       (stm32_port->fifoen &&
+					stm32_port->rxftcfg >= 0))) {
 		if (cflag & CSTOPB)
 			bits = bits + 3; /* 1 start bit + 2 stop bits */
 		else
@@ -791,9 +1103,12 @@ static void stm32_set_termios(struct uart_port *port, struct ktermios *termios,
 		stm32_port->cr1_irq = USART_CR1_RTOIE;
 		writel_relaxed(bits, port->membase + ofs->rtor);
 		cr2 |= USART_CR2_RTOEN;
-		/* Not using dma, enable fifo threshold irq */
-		if (!stm32_port->rx_ch)
-			stm32_port->cr3_irq =  USART_CR3_RXFTIE;
+		/*
+		 * Enable fifo threshold irq in two cases, either when there
+		 * is no DMA, or when wake up over usart, from low power
+		 * state until the DMA gets re-enabled by resume.
+		 */
+		stm32_port->cr3_irq =  USART_CR3_RXFTIE;
 	}
 
 	cr1 |= stm32_port->cr1_irq;
@@ -808,12 +1123,6 @@ static void stm32_set_termios(struct uart_port *port, struct ktermios *termios,
 		cr3 |= USART_CR3_CTSE | USART_CR3_RTSE;
 	}
 
-	/* Handle modem control interrupts */
-	if (UART_ENABLE_MS(port, termios->c_cflag))
-		stm32_enable_ms(port);
-	else
-		stm32_disable_ms(port);
-
 	usartdiv = DIV_ROUND_CLOSEST(port->uartclk, baud);
 
 	/*
@@ -825,11 +1134,11 @@ static void stm32_set_termios(struct uart_port *port, struct ktermios *termios,
 	if (usartdiv < 16) {
 		oversampling = 8;
 		cr1 |= USART_CR1_OVER8;
-		stm32_set_bits(port, ofs->cr1, USART_CR1_OVER8);
+		stm32_usart_set_bits(port, ofs->cr1, USART_CR1_OVER8);
 	} else {
 		oversampling = 16;
 		cr1 &= ~USART_CR1_OVER8;
-		stm32_clr_bits(port, ofs->cr1, USART_CR1_OVER8);
+		stm32_usart_clr_bits(port, ofs->cr1, USART_CR1_OVER8);
 	}
 
 	mantissa = (usartdiv / oversampling) << USART_BRR_DIV_M_SHIFT;
@@ -862,13 +1171,19 @@ static void stm32_set_termios(struct uart_port *port, struct ktermios *termios,
 	if ((termios->c_cflag & CREAD) == 0)
 		port->ignore_status_mask |= USART_SR_DUMMY_RX;
 
-	if (stm32_port->rx_ch)
+	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_config_reg_rs485(&cr1, &cr3,
-				       rs485conf->delay_rts_before_send,
-				       rs485conf->delay_rts_after_send, baud);
+		stm32_usart_config_reg_rs485(&cr1, &cr3, baud, rs485conf);
 		if (rs485conf->flags & SER_RS485_RTS_ON_SEND) {
 			cr3 &= ~USART_CR3_DEP;
 			rs485conf->flags &= ~SER_RS485_RTS_AFTER_SEND;
@@ -882,43 +1197,55 @@ static void stm32_set_termios(struct uart_port *port, struct ktermios *termios,
 		cr1 &= ~(USART_CR1_DEDT_MASK | USART_CR1_DEAT_MASK);
 	}
 
+	/* Enable 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_set_bits(port, ofs->cr1, BIT(cfg->uart_enable_bit));
+	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_type(struct uart_port *port)
+static const char *stm32_usart_type(struct uart_port *port)
 {
 	return (port->type == PORT_STM32) ? DRIVER_NAME : NULL;
 }
 
-static void stm32_release_port(struct uart_port *port)
+static void stm32_usart_release_port(struct uart_port *port)
 {
 }
 
-static int stm32_request_port(struct uart_port *port)
+static int stm32_usart_request_port(struct uart_port *port)
 {
 	return 0;
 }
 
-static void stm32_config_port(struct uart_port *port, int flags)
+static void stm32_usart_config_port(struct uart_port *port, int flags)
 {
 	if (flags & UART_CONFIG_TYPE)
 		port->type = PORT_STM32;
 }
 
 static int
-stm32_verify_port(struct uart_port *port, struct serial_struct *ser)
+stm32_usart_verify_port(struct uart_port *port, struct serial_struct *ser)
 {
 	/* No user changeable parameters */
 	return -EINVAL;
 }
 
-static void stm32_pm(struct uart_port *port, unsigned int state,
-		unsigned int oldstate)
+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);
@@ -932,7 +1259,7 @@ static void stm32_pm(struct uart_port *port, unsigned int state,
 		break;
 	case UART_PM_STATE_OFF:
 		spin_lock_irqsave(&port->lock, flags);
-		stm32_clr_bits(port, ofs->cr1, BIT(cfg->uart_enable_bit));
+		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;
@@ -940,59 +1267,101 @@ static void stm32_pm(struct uart_port *port, unsigned int state,
 }
 
 static const struct uart_ops stm32_uart_ops = {
-	.tx_empty	= stm32_tx_empty,
-	.set_mctrl	= stm32_set_mctrl,
-	.get_mctrl	= stm32_get_mctrl,
-	.stop_tx	= stm32_stop_tx,
-	.start_tx	= stm32_start_tx,
-	.throttle	= stm32_throttle,
-	.unthrottle	= stm32_unthrottle,
-	.stop_rx	= stm32_stop_rx,
-	.enable_ms	= stm32_enable_ms,
-	.break_ctl	= stm32_break_ctl,
-	.startup	= stm32_startup,
-	.shutdown	= stm32_shutdown,
-	.set_termios	= stm32_set_termios,
-	.pm		= stm32_pm,
-	.type		= stm32_type,
-	.release_port	= stm32_release_port,
-	.request_port	= stm32_request_port,
-	.config_port	= stm32_config_port,
-	.verify_port	= stm32_verify_port,
+	.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,
 };
 
-static int stm32_init_port(struct stm32_port *stm32port,
-			  struct platform_device *pdev)
+/*
+ * 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 int stm32_usart_init_port(struct stm32_port *stm32port,
+				 struct platform_device *pdev)
 {
 	struct uart_port *port = &stm32port->port;
 	struct resource *res;
 	int ret;
 
+	ret = platform_get_irq(pdev, 0);
+	if (ret <= 0)
+		return ret ? : -ENODEV;
+
 	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);
-
-	ret = platform_get_irq(pdev, 0);
-	if (ret <= 0)
-		return ret ? : -ENODEV;
 	port->irq = ret;
+	port->rs485_config = stm32_usart_config_rs485;
 
-	port->rs485_config = stm32_config_rs485;
-
-	ret = stm32_init_rs485(port, pdev);
+	ret = stm32_usart_init_rs485(port, pdev);
 	if (ret)
 		return ret;
 
-	if (stm32port->info->cfg.has_wakeup) {
-		stm32port->wakeirq = platform_get_irq_optional(pdev, 1);
-		if (stm32port->wakeirq <= 0 && stm32port->wakeirq != -ENXIO)
-			return stm32port->wakeirq ? : -ENODEV;
-	}
+	if (stm32port->info->cfg.has_wakeup)
+		stm32port->wakeup_src = of_property_read_bool(pdev->dev.of_node,
+							      "wakeup-source");
 
 	stm32port->fifoen = stm32port->info->cfg.has_fifo;
+	if (stm32port->fifoen) {
+		stm32_usart_get_ftcfg(pdev, "st,rx-fifo-threshold-bytes",
+				      &stm32port->rxftcfg);
+		stm32_usart_get_ftcfg(pdev, "st,tx-fifo-threshold-bytes",
+				      &stm32port->txftcfg);
+	}
 
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	port->membase = devm_ioremap_resource(&pdev->dev, res);
@@ -1023,7 +1392,10 @@ static int stm32_init_port(struct stm32_port *stm32port,
 		goto err_clk;
 	}
 
-	/* Both CTS/RTS gpios and "st,hw-flow-ctrl" should not be specified */
+	/*
+	 * 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)) {
@@ -1041,7 +1413,7 @@ static int stm32_init_port(struct stm32_port *stm32port,
 	return ret;
 }
 
-static struct stm32_port *stm32_of_get_stm32_port(struct platform_device *pdev)
+static struct stm32_port *stm32_usart_of_get_port(struct platform_device *pdev)
 {
 	struct device_node *np = pdev->dev.of_node;
 	int id;
@@ -1065,6 +1437,8 @@ static struct stm32_port *stm32_of_get_stm32_port(struct platform_device *pdev)
 	stm32_ports[id].cr1_irq = USART_CR1_RXNEIE;
 	stm32_ports[id].cr3_irq = 0;
 	stm32_ports[id].last_res = RX_BUF_L;
+	stm32_ports[id].rx_dma_buf = 0;
+	stm32_ports[id].tx_dma_buf = 0;
 	return &stm32_ports[id];
 }
 
@@ -1079,30 +1453,28 @@ static const struct of_device_id stm32_match[] = {
 MODULE_DEVICE_TABLE(of, stm32_match);
 #endif
 
-static int stm32_of_dma_rx_probe(struct stm32_port *stm32port,
-				 struct platform_device *pdev)
+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)
 {
 	struct stm32_usart_offsets *ofs = &stm32port->info->ofs;
 	struct uart_port *port = &stm32port->port;
 	struct device *dev = &pdev->dev;
 	struct dma_slave_config config;
-	struct dma_async_tx_descriptor *desc = NULL;
-	dma_cookie_t cookie;
 	int ret;
 
-	/* Request DMA RX channel */
-	stm32port->rx_ch = dma_request_slave_channel(dev, "rx");
-	if (!stm32port->rx_ch) {
-		dev_info(dev, "rx dma alloc failed\n");
-		return -ENODEV;
-	}
 	stm32port->rx_buf = dma_alloc_coherent(&pdev->dev, RX_BUF_L,
-						 &stm32port->rx_dma_buf,
-						 GFP_KERNEL);
-	if (!stm32port->rx_buf) {
-		ret = -ENOMEM;
-		goto alloc_err;
-	}
+					       &stm32port->rx_dma_buf,
+					       GFP_KERNEL);
+	if (!stm32port->rx_buf)
+		return -ENOMEM;
 
 	/* Configure DMA channel */
 	memset(&config, 0, sizeof(config));
@@ -1112,47 +1484,23 @@ static int stm32_of_dma_rx_probe(struct stm32_port *stm32port,
 	ret = dmaengine_slave_config(stm32port->rx_ch, &config);
 	if (ret < 0) {
 		dev_err(dev, "rx dma channel config failed\n");
-		ret = -ENODEV;
-		goto config_err;
-	}
-
-	/* Prepare a DMA cyclic transaction */
-	desc = dmaengine_prep_dma_cyclic(stm32port->rx_ch,
-					 stm32port->rx_dma_buf,
-					 RX_BUF_L, RX_BUF_P, DMA_DEV_TO_MEM,
-					 DMA_PREP_INTERRUPT);
-	if (!desc) {
-		dev_err(dev, "rx dma prep cyclic failed\n");
-		ret = -ENODEV;
-		goto config_err;
+		stm32_usart_of_dma_rx_remove(stm32port, pdev);
+		return ret;
 	}
 
-	/* No callback as dma buffer is drained on usart interrupt */
-	desc->callback = NULL;
-	desc->callback_param = NULL;
-
-	/* Push current DMA transaction in the pending queue */
-	cookie = dmaengine_submit(desc);
-
-	/* Issue pending DMA requests */
-	dma_async_issue_pending(stm32port->rx_ch);
-
 	return 0;
+}
 
-config_err:
-	dma_free_coherent(&pdev->dev,
-			  RX_BUF_L, stm32port->rx_buf,
-			  stm32port->rx_dma_buf);
-
-alloc_err:
-	dma_release_channel(stm32port->rx_ch);
-	stm32port->rx_ch = NULL;
-
-	return ret;
+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_of_dma_tx_probe(struct stm32_port *stm32port,
-				 struct platform_device *pdev)
+static int stm32_usart_of_dma_tx_probe(struct stm32_port *stm32port,
+				       struct platform_device *pdev)
 {
 	struct stm32_usart_offsets *ofs = &stm32port->info->ofs;
 	struct uart_port *port = &stm32port->port;
@@ -1160,21 +1508,11 @@ static int stm32_of_dma_tx_probe(struct stm32_port *stm32port,
 	struct dma_slave_config config;
 	int ret;
 
-	stm32port->tx_dma_busy = false;
-
-	/* Request DMA TX channel */
-	stm32port->tx_ch = dma_request_slave_channel(dev, "tx");
-	if (!stm32port->tx_ch) {
-		dev_info(dev, "tx dma alloc failed\n");
-		return -ENODEV;
-	}
 	stm32port->tx_buf = dma_alloc_coherent(&pdev->dev, TX_BUF_L,
-						 &stm32port->tx_dma_buf,
-						 GFP_KERNEL);
-	if (!stm32port->tx_buf) {
-		ret = -ENOMEM;
-		goto alloc_err;
-	}
+					       &stm32port->tx_dma_buf,
+					       GFP_KERNEL);
+	if (!stm32port->tx_buf)
+		return -ENOMEM;
 
 	/* Configure DMA channel */
 	memset(&config, 0, sizeof(config));
@@ -1184,31 +1522,20 @@ static int stm32_of_dma_tx_probe(struct stm32_port *stm32port,
 	ret = dmaengine_slave_config(stm32port->tx_ch, &config);
 	if (ret < 0) {
 		dev_err(dev, "tx dma channel config failed\n");
-		ret = -ENODEV;
-		goto config_err;
+		stm32_usart_of_dma_tx_remove(stm32port, pdev);
+		return ret;
 	}
 
 	return 0;
-
-config_err:
-	dma_free_coherent(&pdev->dev,
-			  TX_BUF_L, stm32port->tx_buf,
-			  stm32port->tx_dma_buf);
-
-alloc_err:
-	dma_release_channel(stm32port->tx_ch);
-	stm32port->tx_ch = NULL;
-
-	return ret;
 }
 
-static int stm32_serial_probe(struct platform_device *pdev)
+static int stm32_usart_serial_probe(struct platform_device *pdev)
 {
 	const struct of_device_id *match;
 	struct stm32_port *stm32port;
 	int ret;
 
-	stm32port = stm32_of_get_stm32_port(pdev);
+	stm32port = stm32_usart_of_get_port(pdev);
 	if (!stm32port)
 		return -ENODEV;
 
@@ -1218,105 +1545,145 @@ static int stm32_serial_probe(struct platform_device *pdev)
 	else
 		return -EINVAL;
 
-	ret = stm32_init_port(stm32port, pdev);
+	ret = stm32_usart_init_port(stm32port, pdev);
 	if (ret)
 		return ret;
 
-	if (stm32port->wakeirq > 0) {
-		ret = device_init_wakeup(&pdev->dev, true);
-		if (ret)
-			goto err_uninit;
-
-		ret = dev_pm_set_dedicated_wake_irq(&pdev->dev,
-						    stm32port->wakeirq);
+	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_nowup;
-
-		device_set_wakeup_enable(&pdev->dev, false);
+			goto err_deinit_port;
 	}
 
-	ret = uart_add_one_port(&stm32_usart_driver, &stm32port->port);
-	if (ret)
-		goto err_wirq;
+	stm32port->rx_ch = dma_request_chan_linked(&pdev->dev, "rx");
+	if (PTR_ERR(stm32port->rx_ch) == -EPROBE_DEFER) {
+		ret = -EPROBE_DEFER;
+		goto err_wakeirq;
+	}
+	/* 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;
+
+	if (stm32port->rx_ch && stm32_usart_of_dma_rx_probe(stm32port, pdev)) {
+		/* Fall back in interrupt mode */
+		dma_release_chan_linked(&pdev->dev, stm32port->rx_ch);
+		stm32port->rx_ch = NULL;
+	}
 
-	ret = stm32_of_dma_rx_probe(stm32port, pdev);
-	if (ret)
-		dev_info(&pdev->dev, "interrupt mode used for rx (no dma)\n");
+	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;
+	}
 
-	ret = stm32_of_dma_tx_probe(stm32port, pdev);
-	if (ret)
-		dev_info(&pdev->dev, "interrupt mode used for tx (no dma)\n");
+	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_wirq:
-	if (stm32port->wakeirq > 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);
+		dma_release_channel(stm32port->tx_ch);
+	}
+
+	if (stm32port->rx_ch)
+		stm32_usart_of_dma_rx_remove(stm32port, pdev);
+
+err_dma_rx:
+	if (stm32port->rx_ch)
+		dma_release_chan_linked(&pdev->dev, stm32port->rx_ch);
+
+err_wakeirq:
+	if (stm32port->wakeup_src)
 		dev_pm_clear_wake_irq(&pdev->dev);
 
-err_nowup:
-	if (stm32port->wakeirq > 0)
-		device_init_wakeup(&pdev->dev, false);
+err_deinit_port:
+	if (stm32port->wakeup_src)
+		device_set_wakeup_capable(&pdev->dev, false);
 
-err_uninit:
-	clk_disable_unprepare(stm32port->clk);
+	stm32_usart_deinit_port(stm32port);
 
 	return ret;
 }
 
-static int stm32_serial_remove(struct platform_device *pdev)
+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);
 	struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
 	int err;
+	u32 cr3;
 
 	pm_runtime_get_sync(&pdev->dev);
+	err = uart_remove_one_port(&stm32_usart_driver, port);
+	if (err)
+		return(err);
 
-	stm32_clr_bits(port, ofs->cr3, USART_CR3_DMAR);
-
-	if (stm32_port->rx_ch)
-		dma_release_channel(stm32_port->rx_ch);
-
-	if (stm32_port->rx_dma_buf)
-		dma_free_coherent(&pdev->dev,
-				  RX_BUF_L, stm32_port->rx_buf,
-				  stm32_port->rx_dma_buf);
+	pm_runtime_disable(&pdev->dev);
+	pm_runtime_set_suspended(&pdev->dev);
+	pm_runtime_put_noidle(&pdev->dev);
 
-	stm32_clr_bits(port, ofs->cr3, USART_CR3_DMAT);
+	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)
+	if (stm32_port->tx_ch) {
+		stm32_usart_tx_dma_terminate(stm32_port);
+		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_chan_linked(&pdev->dev, stm32_port->rx_ch);
+	}
 
-	if (stm32_port->tx_dma_buf)
-		dma_free_coherent(&pdev->dev,
-				  TX_BUF_L, stm32_port->tx_buf,
-				  stm32_port->tx_dma_buf);
+	stm32_usart_clr_bits(port, ofs->cr3, USART_CR3_DMAT);
 
-	if (stm32_port->wakeirq > 0) {
+	if (stm32_port->wakeup_src) {
 		dev_pm_clear_wake_irq(&pdev->dev);
 		device_init_wakeup(&pdev->dev, false);
 	}
 
-	clk_disable_unprepare(stm32_port->clk);
+	stm32_usart_deinit_port(stm32_port);
 
-	err = uart_remove_one_port(&stm32_usart_driver, port);
-
-	pm_runtime_disable(&pdev->dev);
-	pm_runtime_put_noidle(&pdev->dev);
-
-	return err;
+	return 0;
 }
 
-
 #ifdef CONFIG_SERIAL_STM32_CONSOLE
-static void stm32_console_putchar(struct uart_port *port, int ch)
+static void stm32_usart_console_putchar(struct uart_port *port, int ch)
 {
 	struct stm32_port *stm32_port = to_stm32_port(port);
 	struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
@@ -1327,7 +1694,8 @@ static void stm32_console_putchar(struct uart_port *port, int ch)
 	writel_relaxed(ch, port->membase + ofs->tdr);
 }
 
-static void stm32_console_write(struct console *co, const char *s, unsigned cnt)
+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);
@@ -1351,7 +1719,7 @@ static void stm32_console_write(struct console *co, const char *s, unsigned cnt)
 	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_console_putchar);
+	uart_console_write(port, s, cnt, stm32_usart_console_putchar);
 
 	/* Restore interrupt state */
 	writel_relaxed(old_cr1, port->membase + ofs->cr1);
@@ -1361,7 +1729,7 @@ static void stm32_console_write(struct console *co, const char *s, unsigned cnt)
 	local_irq_restore(flags);
 }
 
-static int stm32_console_setup(struct console *co, char *options)
+static int stm32_usart_console_setup(struct console *co, char *options)
 {
 	struct stm32_port *stm32port;
 	int baud = 9600;
@@ -1380,7 +1748,7 @@ static int stm32_console_setup(struct console *co, char *options)
 	 * 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 == NULL)
+	if (stm32port->port.mapbase == 0 || !stm32port->port.membase)
 		return -ENXIO;
 
 	if (options)
@@ -1392,8 +1760,8 @@ static int stm32_console_setup(struct console *co, char *options)
 static struct console stm32_console = {
 	.name		= STM32_SERIAL_NAME,
 	.device		= uart_console_device,
-	.write		= stm32_console_write,
-	.setup		= stm32_console_setup,
+	.write		= stm32_usart_console_write,
+	.setup		= stm32_usart_console_setup,
 	.flags		= CON_PRINTBUFFER,
 	.index		= -1,
 	.data		= &stm32_usart_driver,
@@ -1414,41 +1782,72 @@ static struct uart_driver stm32_usart_driver = {
 	.cons		= STM32_SERIAL_CONSOLE,
 };
 
-static void __maybe_unused stm32_serial_enable_wakeup(struct uart_port *port,
-						      bool enable)
+static int __maybe_unused stm32_usart_serial_en_wakeup(struct uart_port *port,
+						       bool enable)
 {
 	struct stm32_port *stm32_port = to_stm32_port(port);
 	struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
-	struct stm32_usart_config *cfg = &stm32_port->info->cfg;
-	u32 val;
+	struct tty_port *tport = &port->state->port;
+	unsigned long flags;
+	int ret;
 
-	if (stm32_port->wakeirq <= 0)
-		return;
+	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_clr_bits(port, ofs->cr1, BIT(cfg->uart_enable_bit));
-		stm32_set_bits(port, ofs->cr1, USART_CR1_UESM);
-		val = readl_relaxed(port->membase + ofs->cr3);
-		val &= ~USART_CR3_WUS_MASK;
-		/* Enable Wake up interrupt from low power on start bit */
-		val |= USART_CR3_WUS_START_BIT | USART_CR3_WUFIE;
-		writel_relaxed(val, port->membase + ofs->cr3);
-		stm32_set_bits(port, ofs->cr1, BIT(cfg->uart_enable_bit));
+		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) {
+			/* Avoid race with RX IRQ when DMAR is cleared */
+			spin_lock_irqsave(&port->lock, flags);
+			stm32_usart_clr_bits(port, ofs->cr3, USART_CR3_DMAR);
+			/* Poll data from DMA RX buffer if any */
+			stm32_usart_receive_chars(port, true);
+			dmaengine_terminate_async(stm32_port->rx_ch);
+			spin_unlock_irqrestore(&port->lock, flags);
+		}
+
+		spin_lock_irqsave(&port->lock, flags);
+		/* Poll data from RX FIFO if any */
+		stm32_usart_receive_chars(port, false);
+		spin_unlock_irqrestore(&port->lock, flags);
 	} else {
-		stm32_clr_bits(port, ofs->cr1, USART_CR1_UESM);
+		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_serial_suspend(struct device *dev)
+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))
-		stm32_serial_enable_wakeup(port, true);
-	else
-		stm32_serial_enable_wakeup(port, false);
+	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
@@ -1457,7 +1856,7 @@ static int __maybe_unused stm32_serial_suspend(struct device *dev)
 	 * capabilities.
 	 */
 	if (console_suspend_enabled || !uart_console(port)) {
-		if (device_may_wakeup(dev))
+		if (device_may_wakeup(dev) || device_wakeup_path(dev))
 			pinctrl_pm_select_idle_state(dev);
 		else
 			pinctrl_pm_select_sleep_state(dev);
@@ -1466,19 +1865,23 @@ static int __maybe_unused stm32_serial_suspend(struct device *dev)
 	return 0;
 }
 
-static int __maybe_unused stm32_serial_resume(struct device *dev)
+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))
-		stm32_serial_enable_wakeup(port, false);
+	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_serial_runtime_suspend(struct device *dev)
+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,
@@ -1489,7 +1892,7 @@ static int __maybe_unused stm32_serial_runtime_suspend(struct device *dev)
 	return 0;
 }
 
-static int __maybe_unused stm32_serial_runtime_resume(struct device *dev)
+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,
@@ -1499,14 +1902,15 @@ static int __maybe_unused stm32_serial_runtime_resume(struct device *dev)
 }
 
 static const struct dev_pm_ops stm32_serial_pm_ops = {
-	SET_RUNTIME_PM_OPS(stm32_serial_runtime_suspend,
-			   stm32_serial_runtime_resume, NULL)
-	SET_SYSTEM_SLEEP_PM_OPS(stm32_serial_suspend, stm32_serial_resume)
+	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_serial_probe,
-	.remove		= stm32_serial_remove,
+	.probe		= stm32_usart_serial_probe,
+	.remove		= stm32_usart_serial_remove,
 	.driver	= {
 		.name	= DRIVER_NAME,
 		.pm	= &stm32_serial_pm_ops,
@@ -1514,7 +1918,7 @@ static struct platform_driver stm32_serial_driver = {
 	},
 };
 
-static int __init usart_init(void)
+static int __init stm32_usart_init(void)
 {
 	static char banner[] __initdata = "STM32 USART driver initialized";
 	int ret;
@@ -1532,14 +1936,14 @@ static int __init usart_init(void)
 	return ret;
 }
 
-static void __exit usart_exit(void)
+static void __exit stm32_usart_exit(void)
 {
 	platform_driver_unregister(&stm32_serial_driver);
 	uart_unregister_driver(&stm32_usart_driver);
 }
 
-module_init(usart_init);
-module_exit(usart_exit);
+module_init(stm32_usart_init);
+module_exit(stm32_usart_exit);
 
 MODULE_ALIAS("platform:" DRIVER_NAME);
 MODULE_DESCRIPTION("STMicroelectronics STM32 serial port driver");
diff --git a/drivers/tty/serial/stm32-usart.h b/drivers/tty/serial/stm32-usart.h
index d4c916e78d40..f4708007ec0e 100644
--- a/drivers/tty/serial/stm32-usart.h
+++ b/drivers/tty/serial/stm32-usart.h
@@ -106,7 +106,7 @@ struct stm32_usart_info stm32h7_info = {
 /* USART_SR (F4) / USART_ISR (F7) */
 #define USART_SR_PE		BIT(0)
 #define USART_SR_FE		BIT(1)
-#define USART_SR_NF		BIT(2)
+#define USART_SR_NE		BIT(2)		/* F7 (NF for F4) */
 #define USART_SR_ORE		BIT(3)
 #define USART_SR_IDLE		BIT(4)
 #define USART_SR_RXNE		BIT(5)
@@ -123,13 +123,11 @@ struct stm32_usart_info stm32h7_info = {
 #define USART_SR_SBKF		BIT(18)		/* F7 */
 #define USART_SR_WUF		BIT(20)		/* H7 */
 #define USART_SR_TEACK		BIT(21)		/* F7 */
-#define USART_SR_ERR_MASK	(USART_SR_ORE | USART_SR_FE | USART_SR_PE)
+#define USART_SR_ERR_MASK	(USART_SR_ORE | USART_SR_NE | USART_SR_FE |\
+				 USART_SR_PE)
 /* Dummy bits */
 #define USART_SR_DUMMY_RX	BIT(16)
 
-/* USART_ICR (F7) */
-#define USART_CR_TC		BIT(6)
-
 /* USART_DR */
 #define USART_DR_MASK		GENMASK(8, 0)
 
@@ -216,12 +214,6 @@ struct stm32_usart_info stm32h7_info = {
 #define USART_CR3_TXFTCFG_MASK	GENMASK(31, 29)	/* H7 */
 #define USART_CR3_TXFTCFG_SHIFT	29		/* H7 */
 
-/* TX FIFO threashold set to half of its depth */
-#define USART_CR3_TXFTCFG_HALF	0x2
-
-/* RX FIFO threashold set to half of its depth */
-#define USART_CR3_RXFTCFG_HALF	0x2
-
 /* USART_GTPR */
 #define USART_GTPR_PSC_MASK	GENMASK(7, 0)
 #define USART_GTPR_GT_MASK	GENMASK(15, 8)
@@ -252,9 +244,9 @@ struct stm32_usart_info stm32h7_info = {
 #define STM32_SERIAL_NAME "ttySTM"
 #define STM32_MAX_PORTS 8
 
-#define RX_BUF_L 200		 /* dma rx buffer length     */
-#define RX_BUF_P RX_BUF_L	 /* dma rx buffer period     */
-#define TX_BUF_L 200		 /* dma tx buffer length     */
+#define RX_BUF_L 4096		 /* dma rx buffer length     */
+#define RX_BUF_P (RX_BUF_L / 2)	 /* dma rx buffer period     */
+#define TX_BUF_L RX_BUF_L	 /* dma tx buffer length     */
 
 struct stm32_port {
 	struct uart_port port;
@@ -269,12 +261,16 @@ struct stm32_port {
 	u32 cr1_irq;		 /* USART_CR1_RXNEIE or RTOIE */
 	u32 cr3_irq;		 /* USART_CR3_RXFTIE */
 	int last_res;
-	bool tx_dma_busy;	 /* dma tx busy               */
+	bool throttled;		 /* port throttled            */
 	bool hw_flow_control;
 	bool fifoen;
-	int wakeirq;
+	int rxftcfg;		/* RX FIFO threshold CFG      */
+	int txftcfg;		/* TX FIFO threshold CFG      */
+	bool wakeup_src;
 	int rdr_mask;		/* receive data register mask */
 	struct mctrl_gpios *gpios; /* modem control gpios */
+	struct dma_tx_state rx_dma_state;
+	bool tx_dma_busy;	/* dma tx transaction in progress */
 };
 
 static struct stm32_port stm32_ports[STM32_MAX_PORTS];
diff --git a/include/uapi/linux/serial.h b/include/uapi/linux/serial.h
index 93eb3c496ff1..2d98e65d2a78 100644
--- a/include/uapi/linux/serial.h
+++ b/include/uapi/linux/serial.h
@@ -128,6 +128,8 @@ struct serial_rs485 {
 							   (if supported) */
 	__u32	delay_rts_before_send;	/* Delay before send (milliseconds) */
 	__u32	delay_rts_after_send;	/* Delay after send (milliseconds) */
+	__u32	delay_rts_before_send_ns;	/* Delay (nanoseconds) */
+	__u32	delay_rts_after_send_ns;	/* Delay (nanoseconds) */
 	__u32	padding[5];		/* Memory is cheap, new structs
 					   are a royal PITA .. */
 };
-- 
2.17.1