1 files changed, 241 insertions, 74 deletions

diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index e14813250616..9c59ec128bb4 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -8,6 +8,7 @@
  * Copyright (C) 2004 Pengutronix
  */
 
+#include <linux/circ_buf.h>
 #include <linux/module.h>
 #include <linux/ioport.h>
 #include <linux/init.h>
@@ -26,6 +27,7 @@
 #include <linux/slab.h>
 #include <linux/of.h>
 #include <linux/io.h>
+#include <linux/iopoll.h>
 #include <linux/dma-mapping.h>
 
 #include <asm/irq.h>
@@ -118,6 +120,7 @@
 #define UCR4_OREN	(1<<1)	/* Receiver overrun interrupt enable */
 #define UCR4_DREN	(1<<0)	/* Recv data ready interrupt enable */
 #define UFCR_RXTL_SHF	0	/* Receiver trigger level shift */
+#define UFCR_RXTL_MASK	0x3F	/* Receiver trigger 6 bits wide */
 #define UFCR_DCEDTE	(1<<6)	/* DCE/DTE mode select */
 #define UFCR_RFDIV	(7<<7)	/* Reference freq divider mask */
 #define UFCR_RFDIV_REG(x)	(((x) < 7 ? 6 - (x) : 6) << 7)
@@ -227,6 +230,8 @@ struct imx_port {
 	unsigned int            saved_reg[10];
 	bool			context_saved;
 
+	bool			last_putchar_was_newline;
+
 	enum imx_tx_state	tx_state;
 	struct hrtimer		trigger_start_tx;
 	struct hrtimer		trigger_stop_tx;
@@ -262,6 +267,11 @@ static const struct of_device_id imx_uart_dt_ids[] = {
 };
 MODULE_DEVICE_TABLE(of, imx_uart_dt_ids);
 
+static inline struct imx_port *to_imx_port(struct uart_port *port)
+{
+        return container_of(port, struct imx_port, port);
+}
+
 static inline void imx_uart_writel(struct imx_port *sport, u32 val, u32 offset)
 {
 	writel(val, sport->port.membase + offset);
@@ -362,6 +372,7 @@ static void imx_uart_soft_reset(struct imx_port *sport)
 	sport->idle_counter = 0;
 }
 
+/* called with port.lock taken and irqs off */
 static void imx_uart_disable_loopback_rs485(struct imx_port *sport)
 {
 	unsigned int uts;
@@ -375,7 +386,7 @@ static void imx_uart_disable_loopback_rs485(struct imx_port *sport)
 /* called with port.lock taken and irqs off */
 static void imx_uart_start_rx(struct uart_port *port)
 {
-	struct imx_port *sport = (struct imx_port *)port;
+	struct imx_port *sport = to_imx_port(port);
 	unsigned int ucr1, ucr2;
 
 	ucr1 = imx_uart_readl(sport, UCR1);
@@ -399,7 +410,7 @@ static void imx_uart_start_rx(struct uart_port *port)
 /* called with port.lock taken and irqs off */
 static void imx_uart_stop_tx(struct uart_port *port)
 {
-	struct imx_port *sport = (struct imx_port *)port;
+	struct imx_port *sport = to_imx_port(port);
 	u32 ucr1, ucr4, usr2;
 
 	if (sport->tx_state == OFF)
@@ -462,9 +473,10 @@ static void imx_uart_stop_tx(struct uart_port *port)
 	}
 }
 
+/* called with port.lock taken and irqs off */
 static void imx_uart_stop_rx_with_loopback_ctrl(struct uart_port *port, bool loopback)
 {
-	struct imx_port *sport = (struct imx_port *)port;
+	struct imx_port *sport = to_imx_port(port);
 	u32 ucr1, ucr2, ucr4, uts;
 
 	ucr1 = imx_uart_readl(sport, UCR1);
@@ -509,7 +521,7 @@ static void imx_uart_stop_rx(struct uart_port *port)
 /* called with port.lock taken and irqs off */
 static void imx_uart_enable_ms(struct uart_port *port)
 {
-	struct imx_port *sport = (struct imx_port *)port;
+	struct imx_port *sport = to_imx_port(port);
 
 	mod_timer(&sport->timer, jiffies);
 
@@ -521,7 +533,8 @@ static void imx_uart_dma_tx(struct imx_port *sport);
 /* called with port.lock taken and irqs off */
 static inline void imx_uart_transmit_buffer(struct imx_port *sport)
 {
-	struct circ_buf *xmit = &sport->port.state->xmit;
+	struct tty_port *tport = &sport->port.state->port;
+	unsigned char c;
 
 	if (sport->port.x_char) {
 		/* Send next char */
@@ -531,7 +544,8 @@ static inline void imx_uart_transmit_buffer(struct imx_port *sport)
 		return;
 	}
 
-	if (uart_circ_empty(xmit) || uart_tx_stopped(&sport->port)) {
+	if (kfifo_is_empty(&tport->xmit_fifo) ||
+			uart_tx_stopped(&sport->port)) {
 		imx_uart_stop_tx(&sport->port);
 		return;
 	}
@@ -555,26 +569,22 @@ static inline void imx_uart_transmit_buffer(struct imx_port *sport)
 		return;
 	}
 
-	while (!uart_circ_empty(xmit) &&
-	       !(imx_uart_readl(sport, imx_uart_uts_reg(sport)) & UTS_TXFULL)) {
-		/* send xmit->buf[xmit->tail]
-		 * out the port here */
-		imx_uart_writel(sport, xmit->buf[xmit->tail], URTX0);
-		uart_xmit_advance(&sport->port, 1);
-	}
+	while (!(imx_uart_readl(sport, imx_uart_uts_reg(sport)) & UTS_TXFULL) &&
+			uart_fifo_get(&sport->port, &c))
+		imx_uart_writel(sport, c, URTX0);
 
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+	if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)
 		uart_write_wakeup(&sport->port);
 
-	if (uart_circ_empty(xmit))
+	if (kfifo_is_empty(&tport->xmit_fifo))
 		imx_uart_stop_tx(&sport->port);
 }
 
 static void imx_uart_dma_tx_callback(void *data)
 {
 	struct imx_port *sport = data;
+	struct tty_port *tport = &sport->port.state->port;
 	struct scatterlist *sgl = &sport->tx_sgl[0];
-	struct circ_buf *xmit = &sport->port.state->xmit;
 	unsigned long flags;
 	u32 ucr1;
 
@@ -592,10 +602,11 @@ static void imx_uart_dma_tx_callback(void *data)
 
 	sport->dma_is_txing = 0;
 
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+	if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)
 		uart_write_wakeup(&sport->port);
 
-	if (!uart_circ_empty(xmit) && !uart_tx_stopped(&sport->port))
+	if (!kfifo_is_empty(&tport->xmit_fifo) &&
+			!uart_tx_stopped(&sport->port))
 		imx_uart_dma_tx(sport);
 	else if (sport->port.rs485.flags & SER_RS485_ENABLED) {
 		u32 ucr4 = imx_uart_readl(sport, UCR4);
@@ -609,7 +620,7 @@ static void imx_uart_dma_tx_callback(void *data)
 /* called with port.lock taken and irqs off */
 static void imx_uart_dma_tx(struct imx_port *sport)
 {
-	struct circ_buf *xmit = &sport->port.state->xmit;
+	struct tty_port *tport = &sport->port.state->port;
 	struct scatterlist *sgl = sport->tx_sgl;
 	struct dma_async_tx_descriptor *desc;
 	struct dma_chan	*chan = sport->dma_chan_tx;
@@ -624,18 +635,10 @@ static void imx_uart_dma_tx(struct imx_port *sport)
 	ucr4 &= ~UCR4_TCEN;
 	imx_uart_writel(sport, ucr4, UCR4);
 
-	sport->tx_bytes = uart_circ_chars_pending(xmit);
-
-	if (xmit->tail < xmit->head || xmit->head == 0) {
-		sport->dma_tx_nents = 1;
-		sg_init_one(sgl, xmit->buf + xmit->tail, sport->tx_bytes);
-	} else {
-		sport->dma_tx_nents = 2;
-		sg_init_table(sgl, 2);
-		sg_set_buf(sgl, xmit->buf + xmit->tail,
-				UART_XMIT_SIZE - xmit->tail);
-		sg_set_buf(sgl + 1, xmit->buf, xmit->head);
-	}
+	sg_init_table(sgl, ARRAY_SIZE(sport->tx_sgl));
+	sport->tx_bytes = kfifo_len(&tport->xmit_fifo);
+	sport->dma_tx_nents = kfifo_dma_out_prepare(&tport->xmit_fifo, sgl,
+			ARRAY_SIZE(sport->tx_sgl), sport->tx_bytes);
 
 	ret = dma_map_sg(dev, sgl, sport->dma_tx_nents, DMA_TO_DEVICE);
 	if (ret == 0) {
@@ -653,8 +656,7 @@ static void imx_uart_dma_tx(struct imx_port *sport)
 	desc->callback = imx_uart_dma_tx_callback;
 	desc->callback_param = sport;
 
-	dev_dbg(dev, "TX: prepare to send %lu bytes by DMA.\n",
-			uart_circ_chars_pending(xmit));
+	dev_dbg(dev, "TX: prepare to send %u bytes by DMA.\n", sport->tx_bytes);
 
 	ucr1 = imx_uart_readl(sport, UCR1);
 	ucr1 |= UCR1_TXDMAEN;
@@ -670,10 +672,11 @@ static void imx_uart_dma_tx(struct imx_port *sport)
 /* called with port.lock taken and irqs off */
 static void imx_uart_start_tx(struct uart_port *port)
 {
-	struct imx_port *sport = (struct imx_port *)port;
+	struct imx_port *sport = to_imx_port(port);
+	struct tty_port *tport = &sport->port.state->port;
 	u32 ucr1;
 
-	if (!sport->port.x_char && uart_circ_empty(&port->state->xmit))
+	if (!sport->port.x_char && kfifo_is_empty(&tport->xmit_fifo))
 		return;
 
 	/*
@@ -749,7 +752,7 @@ static void imx_uart_start_tx(struct uart_port *port)
 			return;
 		}
 
-		if (!uart_circ_empty(&port->state->xmit) &&
+		if (!kfifo_is_empty(&tport->xmit_fifo) &&
 		    !uart_tx_stopped(port))
 			imx_uart_dma_tx(sport);
 		return;
@@ -763,6 +766,21 @@ static irqreturn_t __imx_uart_rtsint(int irq, void *dev_id)
 
 	imx_uart_writel(sport, USR1_RTSD, USR1);
 	usr1 = imx_uart_readl(sport, USR1) & USR1_RTSS;
+	/*
+	 * Update sport->old_status here, so any follow-up calls to
+	 * imx_uart_mctrl_check() will be able to recognize that RTS
+	 * state changed since last imx_uart_mctrl_check() call.
+	 *
+	 * In case RTS has been detected as asserted here and later on
+	 * deasserted by the time imx_uart_mctrl_check() was called,
+	 * imx_uart_mctrl_check() can detect the RTS state change and
+	 * trigger uart_handle_cts_change() to unblock the port for
+	 * further TX transfers.
+	 */
+	if (usr1 & USR1_RTSS)
+		sport->old_status |= TIOCM_CTS;
+	else
+		sport->old_status &= ~TIOCM_CTS;
 	uart_handle_cts_change(&sport->port, usr1);
 	wake_up_interruptible(&sport->port.state->port.delta_msr_wait);
 
@@ -804,6 +822,8 @@ static irqreturn_t imx_uart_txint(int irq, void *dev_id)
  * issuing soft reset to the UART (just stop/start of RX does not help). Note
  * that what we do here is sending isolated start bit about 2.4 times shorter
  * than it is to be on UART configured baud rate.
+ *
+ * Called with port.lock taken and irqs off.
  */
 static void imx_uart_check_flood(struct imx_port *sport, u32 usr2)
 {
@@ -839,6 +859,7 @@ static void imx_uart_check_flood(struct imx_port *sport, u32 usr2)
 	}
 }
 
+/* called with port.lock taken and irqs off */
 static irqreturn_t __imx_uart_rxint(int irq, void *dev_id)
 {
 	struct imx_port *sport = dev_id;
@@ -917,6 +938,7 @@ static void imx_uart_clear_rx_errors(struct imx_port *sport);
 /*
  * We have a modem side uart, so the meanings of RTS and CTS are inverted.
  */
+/* called with port.lock taken and irqs off */
 static unsigned int imx_uart_get_hwmctrl(struct imx_port *sport)
 {
 	unsigned int tmp = TIOCM_DSR;
@@ -939,6 +961,8 @@ static unsigned int imx_uart_get_hwmctrl(struct imx_port *sport)
 
 /*
  * Handle any change of modem status signal since we were last called.
+ *
+ * Called with port.lock taken and irqs off.
  */
 static void imx_uart_mctrl_check(struct imx_port *sport)
 {
@@ -1050,7 +1074,7 @@ static irqreturn_t imx_uart_int(int irq, void *dev_id)
  */
 static unsigned int imx_uart_tx_empty(struct uart_port *port)
 {
-	struct imx_port *sport = (struct imx_port *)port;
+	struct imx_port *sport = to_imx_port(port);
 	unsigned int ret;
 
 	ret = (imx_uart_readl(sport, USR2) & USR2_TXDC) ?  TIOCSER_TEMT : 0;
@@ -1065,7 +1089,7 @@ static unsigned int imx_uart_tx_empty(struct uart_port *port)
 /* called with port.lock taken and irqs off */
 static unsigned int imx_uart_get_mctrl(struct uart_port *port)
 {
-	struct imx_port *sport = (struct imx_port *)port;
+	struct imx_port *sport = to_imx_port(port);
 	unsigned int ret = imx_uart_get_hwmctrl(sport);
 
 	mctrl_gpio_get(sport->gpios, &ret);
@@ -1076,7 +1100,7 @@ static unsigned int imx_uart_get_mctrl(struct uart_port *port)
 /* called with port.lock taken and irqs off */
 static void imx_uart_set_mctrl(struct uart_port *port, unsigned int mctrl)
 {
-	struct imx_port *sport = (struct imx_port *)port;
+	struct imx_port *sport = to_imx_port(port);
 	u32 ucr3, uts;
 
 	if (!(port->rs485.flags & SER_RS485_ENABLED)) {
@@ -1119,7 +1143,7 @@ static void imx_uart_set_mctrl(struct uart_port *port, unsigned int mctrl)
  */
 static void imx_uart_break_ctl(struct uart_port *port, int break_state)
 {
-	struct imx_port *sport = (struct imx_port *)port;
+	struct imx_port *sport = to_imx_port(port);
 	unsigned long flags;
 	u32 ucr1;
 
@@ -1278,6 +1302,7 @@ static int imx_uart_start_rx_dma(struct imx_port *sport)
 	return 0;
 }
 
+/* called with port.lock taken and irqs off */
 static void imx_uart_clear_rx_errors(struct imx_port *sport)
 {
 	struct tty_port *port = &sport->port.state->port;
@@ -1312,7 +1337,7 @@ static void imx_uart_clear_rx_errors(struct imx_port *sport)
 
 }
 
-#define TXTL_DEFAULT 2 /* reset default */
+#define TXTL_DEFAULT 8
 #define RXTL_DEFAULT 8 /* 8 characters or aging timer */
 #define TXTL_DMA 8 /* DMA burst setting */
 #define RXTL_DMA 9 /* DMA burst setting */
@@ -1408,6 +1433,7 @@ err:
 	return ret;
 }
 
+/* called with port.lock taken and irqs off */
 static void imx_uart_enable_dma(struct imx_port *sport)
 {
 	u32 ucr1;
@@ -1441,7 +1467,7 @@ static void imx_uart_disable_dma(struct imx_port *sport)
 
 static int imx_uart_startup(struct uart_port *port)
 {
-	struct imx_port *sport = (struct imx_port *)port;
+	struct imx_port *sport = to_imx_port(port);
 	int retval;
 	unsigned long flags;
 	int dma_is_inited = 0;
@@ -1555,9 +1581,10 @@ static int imx_uart_startup(struct uart_port *port)
 
 static void imx_uart_shutdown(struct uart_port *port)
 {
-	struct imx_port *sport = (struct imx_port *)port;
+	struct imx_port *sport = to_imx_port(port);
 	unsigned long flags;
 	u32 ucr1, ucr2, ucr4, uts;
+	int loops;
 
 	if (sport->dma_is_enabled) {
 		dmaengine_terminate_sync(sport->dma_chan_tx);
@@ -1620,6 +1647,56 @@ static void imx_uart_shutdown(struct uart_port *port)
 	ucr4 &= ~UCR4_TCEN;
 	imx_uart_writel(sport, ucr4, UCR4);
 
+	/*
+	 * We have to ensure the tx state machine ends up in OFF. This
+	 * is especially important for rs485 where we must not leave
+	 * the RTS signal high, blocking the bus indefinitely.
+	 *
+	 * All interrupts are now disabled, so imx_uart_stop_tx() will
+	 * no longer be called from imx_uart_transmit_buffer(). It may
+	 * still be called via the hrtimers, and if those are in play,
+	 * we have to honour the delays.
+	 */
+	if (sport->tx_state == WAIT_AFTER_RTS || sport->tx_state == SEND)
+		imx_uart_stop_tx(port);
+
+	/*
+	 * In many cases (rs232 mode, or if tx_state was
+	 * WAIT_AFTER_RTS, or if tx_state was SEND and there is no
+	 * delay_rts_after_send), this will have moved directly to
+	 * OFF. In rs485 mode, tx_state might already have been
+	 * WAIT_AFTER_SEND and the hrtimer thus already started, or
+	 * the above imx_uart_stop_tx() call could have started it. In
+	 * those cases, we have to wait for the hrtimer to fire and
+	 * complete the transition to OFF.
+	 */
+	loops = port->rs485.flags & SER_RS485_ENABLED ?
+		port->rs485.delay_rts_after_send : 0;
+	while (sport->tx_state != OFF && loops--) {
+		uart_port_unlock_irqrestore(&sport->port, flags);
+		msleep(1);
+		uart_port_lock_irqsave(&sport->port, &flags);
+	}
+
+	if (sport->tx_state != OFF) {
+		dev_warn(sport->port.dev, "unexpected tx_state %d\n",
+			 sport->tx_state);
+		/*
+		 * This machine may be busted, but ensure the RTS
+		 * signal is inactive in order not to block other
+		 * devices.
+		 */
+		if (port->rs485.flags & SER_RS485_ENABLED) {
+			ucr2 = imx_uart_readl(sport, UCR2);
+			if (port->rs485.flags & SER_RS485_RTS_AFTER_SEND)
+				imx_uart_rts_active(sport, &ucr2);
+			else
+				imx_uart_rts_inactive(sport, &ucr2);
+			imx_uart_writel(sport, ucr2, UCR2);
+		}
+		sport->tx_state = OFF;
+	}
+
 	uart_port_unlock_irqrestore(&sport->port, flags);
 
 	clk_disable_unprepare(sport->clk_per);
@@ -1629,7 +1706,7 @@ static void imx_uart_shutdown(struct uart_port *port)
 /* called with port.lock taken and irqs off */
 static void imx_uart_flush_buffer(struct uart_port *port)
 {
-	struct imx_port *sport = (struct imx_port *)port;
+	struct imx_port *sport = to_imx_port(port);
 	struct scatterlist *sgl = &sport->tx_sgl[0];
 
 	if (!sport->dma_chan_tx)
@@ -1656,7 +1733,7 @@ static void
 imx_uart_set_termios(struct uart_port *port, struct ktermios *termios,
 		     const struct ktermios *old)
 {
-	struct imx_port *sport = (struct imx_port *)port;
+	struct imx_port *sport = to_imx_port(port);
 	unsigned long flags;
 	u32 ucr2, old_ucr2, ufcr;
 	unsigned int baud, quot;
@@ -1859,7 +1936,7 @@ imx_uart_verify_port(struct uart_port *port, struct serial_struct *ser)
 
 static int imx_uart_poll_init(struct uart_port *port)
 {
-	struct imx_port *sport = (struct imx_port *)port;
+	struct imx_port *sport = to_imx_port(port);
 	unsigned long flags;
 	u32 ucr1, ucr2;
 	int retval;
@@ -1908,7 +1985,7 @@ static int imx_uart_poll_init(struct uart_port *port)
 
 static int imx_uart_poll_get_char(struct uart_port *port)
 {
-	struct imx_port *sport = (struct imx_port *)port;
+	struct imx_port *sport = to_imx_port(port);
 	if (!(imx_uart_readl(sport, USR2) & USR2_RDR))
 		return NO_POLL_CHAR;
 
@@ -1917,7 +1994,7 @@ static int imx_uart_poll_get_char(struct uart_port *port)
 
 static void imx_uart_poll_put_char(struct uart_port *port, unsigned char c)
 {
-	struct imx_port *sport = (struct imx_port *)port;
+	struct imx_port *sport = to_imx_port(port);
 	unsigned int status;
 
 	/* drain */
@@ -1939,8 +2016,8 @@ static void imx_uart_poll_put_char(struct uart_port *port, unsigned char c)
 static int imx_uart_rs485_config(struct uart_port *port, struct ktermios *termios,
 				 struct serial_rs485 *rs485conf)
 {
-	struct imx_port *sport = (struct imx_port *)port;
-	u32 ucr2;
+	struct imx_port *sport = to_imx_port(port);
+	u32 ucr2, ufcr;
 
 	if (rs485conf->flags & SER_RS485_ENABLED) {
 		/* Enable receiver if low-active RTS signal is requested */
@@ -1959,8 +2036,13 @@ static int imx_uart_rs485_config(struct uart_port *port, struct ktermios *termio
 
 	/* Make sure Rx is enabled in case Tx is active with Rx disabled */
 	if (!(rs485conf->flags & SER_RS485_ENABLED) ||
-	    rs485conf->flags & SER_RS485_RX_DURING_TX)
+	    rs485conf->flags & SER_RS485_RX_DURING_TX) {
+		/* If the receiver trigger is 0, set it to a default value */
+		ufcr = imx_uart_readl(sport, UFCR);
+		if ((ufcr & UFCR_RXTL_MASK) == 0)
+			imx_uart_setup_ufcr(sport, TXTL_DEFAULT, RXTL_DEFAULT);
 		imx_uart_start_rx(port);
+	}
 
 	return 0;
 }
@@ -1993,32 +2075,40 @@ static struct imx_port *imx_uart_ports[UART_NR];
 #if IS_ENABLED(CONFIG_SERIAL_IMX_CONSOLE)
 static void imx_uart_console_putchar(struct uart_port *port, unsigned char ch)
 {
-	struct imx_port *sport = (struct imx_port *)port;
+	struct imx_port *sport = to_imx_port(port);
 
 	while (imx_uart_readl(sport, imx_uart_uts_reg(sport)) & UTS_TXFULL)
 		barrier();
 
 	imx_uart_writel(sport, ch, URTX0);
+
+	sport->last_putchar_was_newline = (ch == '\n');
 }
 
-/*
- * Interrupts are disabled on entering
- */
-static void
-imx_uart_console_write(struct console *co, const char *s, unsigned int count)
+static void imx_uart_console_device_lock(struct console *co, unsigned long *flags)
+{
+	struct uart_port *up = &imx_uart_ports[co->index]->port;
+
+	return __uart_port_lock_irqsave(up, flags);
+}
+
+static void imx_uart_console_device_unlock(struct console *co, unsigned long flags)
+{
+	struct uart_port *up = &imx_uart_ports[co->index]->port;
+
+	return __uart_port_unlock_irqrestore(up, flags);
+}
+
+static void imx_uart_console_write_atomic(struct console *co,
+					  struct nbcon_write_context *wctxt)
 {
 	struct imx_port *sport = imx_uart_ports[co->index];
+	struct uart_port *port = &sport->port;
 	struct imx_port_ucrs old_ucr;
-	unsigned long flags;
-	unsigned int ucr1;
-	int locked = 1;
+	unsigned int ucr1, usr2;
 
-	if (sport->port.sysrq)
-		locked = 0;
-	else if (oops_in_progress)
-		locked = uart_port_trylock_irqsave(&sport->port, &flags);
-	else
-		uart_port_lock_irqsave(&sport->port, &flags);
+	if (!nbcon_enter_unsafe(wctxt))
+		return;
 
 	/*
 	 *	First, save UCR1/2/3 and then disable interrupts
@@ -2032,21 +2122,88 @@ imx_uart_console_write(struct console *co, const char *s, unsigned int count)
 	ucr1 &= ~(UCR1_TRDYEN | UCR1_RRDYEN | UCR1_RTSDEN);
 
 	imx_uart_writel(sport, ucr1, UCR1);
-
 	imx_uart_writel(sport, old_ucr.ucr2 | UCR2_TXEN, UCR2);
 
-	uart_console_write(&sport->port, s, count, imx_uart_console_putchar);
+	if (!sport->last_putchar_was_newline)
+		uart_console_write(port, "\n", 1, imx_uart_console_putchar);
+	uart_console_write(port, wctxt->outbuf, wctxt->len,
+			   imx_uart_console_putchar);
 
 	/*
 	 *	Finally, wait for transmitter to become empty
 	 *	and restore UCR1/2/3
 	 */
-	while (!(imx_uart_readl(sport, USR2) & USR2_TXDC));
+	read_poll_timeout_atomic(imx_uart_readl, usr2, usr2 & USR2_TXDC,
+				 0, USEC_PER_SEC, false, sport, USR2);
+	imx_uart_ucrs_restore(sport, &old_ucr);
+
+	nbcon_exit_unsafe(wctxt);
+}
+
+static void imx_uart_console_write_thread(struct console *co,
+					  struct nbcon_write_context *wctxt)
+{
+	struct imx_port *sport = imx_uart_ports[co->index];
+	struct uart_port *port = &sport->port;
+	struct imx_port_ucrs old_ucr;
+	unsigned int ucr1, usr2;
+
+	if (!nbcon_enter_unsafe(wctxt))
+		return;
+
+	/*
+	 *	First, save UCR1/2/3 and then disable interrupts
+	 */
+	imx_uart_ucrs_save(sport, &old_ucr);
+	ucr1 = old_ucr.ucr1;
 
+	if (imx_uart_is_imx1(sport))
+		ucr1 |= IMX1_UCR1_UARTCLKEN;
+	ucr1 |= UCR1_UARTEN;
+	ucr1 &= ~(UCR1_TRDYEN | UCR1_RRDYEN | UCR1_RTSDEN);
+
+	imx_uart_writel(sport, ucr1, UCR1);
+	imx_uart_writel(sport, old_ucr.ucr2 | UCR2_TXEN, UCR2);
+
+	if (nbcon_exit_unsafe(wctxt)) {
+		int len = READ_ONCE(wctxt->len);
+		int i;
+
+		/*
+		 * Write out the message. Toggle unsafe for each byte in order
+		 * to give another (higher priority) context the opportunity
+		 * for a friendly takeover. If such a takeover occurs, this
+		 * context must reacquire ownership in order to perform final
+		 * actions (such as re-enabling the interrupts).
+		 *
+		 * IMPORTANT: wctxt->outbuf and wctxt->len are no longer valid
+		 *	      after a reacquire so writing the message must be
+		 *	      aborted.
+		 */
+		for (i = 0; i < len; i++) {
+			if (!nbcon_enter_unsafe(wctxt))
+				break;
+
+			uart_console_write(port, wctxt->outbuf + i, 1,
+					   imx_uart_console_putchar);
+
+			if (!nbcon_exit_unsafe(wctxt))
+				break;
+		}
+	}
+
+	while (!nbcon_enter_unsafe(wctxt))
+		nbcon_reacquire_nobuf(wctxt);
+
+	/*
+	 *	Finally, wait for transmitter to become empty
+	 *	and restore UCR1/2/3
+	 */
+	read_poll_timeout(imx_uart_readl, usr2, usr2 & USR2_TXDC,
+			  0, USEC_PER_SEC, false, sport, USR2);
 	imx_uart_ucrs_restore(sport, &old_ucr);
 
-	if (locked)
-		uart_port_unlock_irqrestore(&sport->port, flags);
+	nbcon_exit_unsafe(wctxt);
 }
 
 /*
@@ -2138,6 +2295,8 @@ imx_uart_console_setup(struct console *co, char *options)
 	if (retval)
 		goto error_console;
 
+	sport->last_putchar_was_newline = true;
+
 	if (options)
 		uart_parse_options(options, &baud, &parity, &bits, &flow);
 	else
@@ -2174,11 +2333,14 @@ imx_uart_console_exit(struct console *co)
 static struct uart_driver imx_uart_uart_driver;
 static struct console imx_uart_console = {
 	.name		= DEV_NAME,
-	.write		= imx_uart_console_write,
+	.write_atomic	= imx_uart_console_write_atomic,
+	.write_thread	= imx_uart_console_write_thread,
+	.device_lock	= imx_uart_console_device_lock,
+	.device_unlock	= imx_uart_console_device_unlock,
+	.flags		= CON_PRINTBUFFER | CON_NBCON,
 	.device		= uart_console_device,
 	.setup		= imx_uart_console_setup,
 	.exit		= imx_uart_console_exit,
-	.flags		= CON_PRINTBUFFER,
 	.index		= -1,
 	.data		= &imx_uart_uart_driver,
 };
@@ -2525,10 +2687,13 @@ static void imx_uart_save_context(struct imx_port *sport)
 	uart_port_unlock_irqrestore(&sport->port, flags);
 }
 
+/* called with irq off */
 static void imx_uart_enable_wakeup(struct imx_port *sport, bool on)
 {
 	u32 ucr3;
 
+	uart_port_lock_irq(&sport->port);
+
 	ucr3 = imx_uart_readl(sport, UCR3);
 	if (on) {
 		imx_uart_writel(sport, USR1_AWAKE, USR1);
@@ -2548,6 +2713,8 @@ static void imx_uart_enable_wakeup(struct imx_port *sport, bool on)
 		}
 		imx_uart_writel(sport, ucr1, UCR1);
 	}
+
+	uart_port_unlock_irq(&sport->port);
 }
 
 static int imx_uart_suspend_noirq(struct device *dev)
@@ -2647,7 +2814,7 @@ static const struct dev_pm_ops imx_uart_pm_ops = {
 
 static struct platform_driver imx_uart_platform_driver = {
 	.probe = imx_uart_probe,
-	.remove_new = imx_uart_remove,
+	.remove = imx_uart_remove,
 
 	.driver = {
 		.name = "imx-uart",