1 files changed, 49 insertions, 27 deletions

diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c
index 67fa113f77d4..888e01fbd9c5 100644
--- a/drivers/tty/serial/fsl_lpuart.c
+++ b/drivers/tty/serial/fsl_lpuart.c
@@ -12,6 +12,7 @@
 #include <linux/dmaengine.h>
 #include <linux/dmapool.h>
 #include <linux/io.h>
+#include <linux/iopoll.h>
 #include <linux/irq.h>
 #include <linux/module.h>
 #include <linux/of.h>
@@ -404,33 +405,6 @@ static unsigned int lpuart_get_baud_clk_rate(struct lpuart_port *sport)
 #define lpuart_enable_clks(x)	__lpuart_enable_clks(x, true)
 #define lpuart_disable_clks(x)	__lpuart_enable_clks(x, false)
 
-static int lpuart_global_reset(struct lpuart_port *sport)
-{
-	struct uart_port *port = &sport->port;
-	void __iomem *global_addr;
-	int ret;
-
-	if (uart_console(port))
-		return 0;
-
-	ret = clk_prepare_enable(sport->ipg_clk);
-	if (ret) {
-		dev_err(sport->port.dev, "failed to enable uart ipg clk: %d\n", ret);
-		return ret;
-	}
-
-	if (is_imx7ulp_lpuart(sport) || is_imx8qxp_lpuart(sport)) {
-		global_addr = port->membase + UART_GLOBAL - IMX_REG_OFF;
-		writel(UART_GLOBAL_RST, global_addr);
-		usleep_range(GLOBAL_RST_MIN_US, GLOBAL_RST_MAX_US);
-		writel(0, global_addr);
-		usleep_range(GLOBAL_RST_MIN_US, GLOBAL_RST_MAX_US);
-	}
-
-	clk_disable_unprepare(sport->ipg_clk);
-	return 0;
-}
-
 static void lpuart_stop_tx(struct uart_port *port)
 {
 	unsigned char temp;
@@ -2636,6 +2610,54 @@ static const struct serial_rs485 lpuart_rs485_supported = {
 	/* delay_rts_* and RX_DURING_TX are not supported */
 };
 
+static int lpuart_global_reset(struct lpuart_port *sport)
+{
+	struct uart_port *port = &sport->port;
+	void __iomem *global_addr;
+	unsigned long ctrl, bd;
+	unsigned int val = 0;
+	int ret;
+
+	ret = clk_prepare_enable(sport->ipg_clk);
+	if (ret) {
+		dev_err(sport->port.dev, "failed to enable uart ipg clk: %d\n", ret);
+		return ret;
+	}
+
+	if (is_imx7ulp_lpuart(sport) || is_imx8qxp_lpuart(sport)) {
+		/*
+		 * If the transmitter is used by earlycon, wait for transmit engine to
+		 * complete and then reset.
+		 */
+		ctrl = lpuart32_read(port, UARTCTRL);
+		if (ctrl & UARTCTRL_TE) {
+			bd = lpuart32_read(&sport->port, UARTBAUD);
+			if (read_poll_timeout(lpuart32_tx_empty, val, val, 1, 100000, false,
+					      port)) {
+				dev_warn(sport->port.dev,
+					 "timeout waiting for transmit engine to complete\n");
+				clk_disable_unprepare(sport->ipg_clk);
+				return 0;
+			}
+		}
+
+		global_addr = port->membase + UART_GLOBAL - IMX_REG_OFF;
+		writel(UART_GLOBAL_RST, global_addr);
+		usleep_range(GLOBAL_RST_MIN_US, GLOBAL_RST_MAX_US);
+		writel(0, global_addr);
+		usleep_range(GLOBAL_RST_MIN_US, GLOBAL_RST_MAX_US);
+
+		/* Recover the transmitter for earlycon. */
+		if (ctrl & UARTCTRL_TE) {
+			lpuart32_write(port, bd, UARTBAUD);
+			lpuart32_write(port, ctrl, UARTCTRL);
+		}
+	}
+
+	clk_disable_unprepare(sport->ipg_clk);
+	return 0;
+}
+
 static int lpuart_probe(struct platform_device *pdev)
 {
 	const struct lpuart_soc_data *sdata = of_device_get_match_data(&pdev->dev);