openwrt/target/linux/layerscape/patches-4.9/816-tty-serial-support-layerscape.patch

From c35aec61e5bb0faafb2847a0d750ebd7345a4b0f Mon Sep 17 00:00:00 2001
From: Yangbo Lu <yangbo.lu@nxp.com>
Date: Wed, 17 Jan 2018 15:40:24 +0800
Subject: [PATCH 28/30] tty: serial: support layerscape

This is an integrated patch for layerscape uart support.

Signed-off-by: Nikita Yushchenko <nikita.yoush@cogentembedded.com>
Signed-off-by: Yuan Yao <yao.yuan@nxp.com>
Signed-off-by: Stefan Agner <stefan@agner.ch>
Signed-off-by: Yangbo Lu <yangbo.lu@nxp.com>
---
 drivers/tty/serial/fsl_lpuart.c | 66 ++++++++++++++++++++++++++++-------------
 1 file changed, 46 insertions(+), 20 deletions(-)

--- a/drivers/tty/serial/fsl_lpuart.c
+++ b/drivers/tty/serial/fsl_lpuart.c
@@ -231,6 +231,8 @@
 #define DEV_NAME	"ttyLP"
 #define UART_NR		6
 
+static DECLARE_BITMAP(linemap, UART_NR);
+
 struct lpuart_port {
 	struct uart_port	port;
 	struct clk		*clk;
@@ -1348,6 +1350,18 @@ lpuart_set_termios(struct uart_port *por
 	/* ask the core to calculate the divisor */
 	baud = uart_get_baud_rate(port, termios, old, 50, port->uartclk / 16);
 
+	/*
+	 * Need to update the Ring buffer length according to the selected
+	 * baud rate and restart Rx DMA path.
+	 *
+	 * Since timer function acqures sport->port.lock, need to stop before
+	 * acquring same lock because otherwise del_timer_sync() can deadlock.
+	 */
+	if (old && sport->lpuart_dma_rx_use) {
+		del_timer_sync(&sport->lpuart_timer);
+		lpuart_dma_rx_free(&sport->port);
+	}
+
 	spin_lock_irqsave(&sport->port.lock, flags);
 
 	sport->port.read_status_mask = 0;
@@ -1397,22 +1411,11 @@ lpuart_set_termios(struct uart_port *por
 	/* restore control register */
 	writeb(old_cr2, sport->port.membase + UARTCR2);
 
-	/*
-	 * If new baud rate is set, we will also need to update the Ring buffer
-	 * length according to the selected baud rate and restart Rx DMA path.
-	 */
-	if (old) {
-		if (sport->lpuart_dma_rx_use) {
-			del_timer_sync(&sport->lpuart_timer);
-			lpuart_dma_rx_free(&sport->port);
-		}
-
-		if (sport->dma_rx_chan && !lpuart_start_rx_dma(sport)) {
-			sport->lpuart_dma_rx_use = true;
+	if (old && sport->lpuart_dma_rx_use) {
+		if (!lpuart_start_rx_dma(sport))
 			rx_dma_timer_init(sport);
-		} else {
+		else
 			sport->lpuart_dma_rx_use = false;
-		}
 	}
 
 	spin_unlock_irqrestore(&sport->port.lock, flags);
@@ -1640,6 +1643,13 @@ lpuart_console_write(struct console *co,
 {
 	struct lpuart_port *sport = lpuart_ports[co->index];
 	unsigned char  old_cr2, cr2;
+	unsigned long flags;
+	int locked = 1;
+
+	if (sport->port.sysrq || oops_in_progress)
+		locked = spin_trylock_irqsave(&sport->port.lock, flags);
+	else
+		spin_lock_irqsave(&sport->port.lock, flags);
 
 	/* first save CR2 and then disable interrupts */
 	cr2 = old_cr2 = readb(sport->port.membase + UARTCR2);
@@ -1654,6 +1664,9 @@ lpuart_console_write(struct console *co,
 		barrier();
 
 	writeb(old_cr2, sport->port.membase + UARTCR2);
+
+	if (locked)
+		spin_unlock_irqrestore(&sport->port.lock, flags);
 }
 
 static void
@@ -1661,6 +1674,13 @@ lpuart32_console_write(struct console *c
 {
 	struct lpuart_port *sport = lpuart_ports[co->index];
 	unsigned long  old_cr, cr;
+	unsigned long flags;
+	int locked = 1;
+
+	if (sport->port.sysrq || oops_in_progress)
+		locked = spin_trylock_irqsave(&sport->port.lock, flags);
+	else
+		spin_lock_irqsave(&sport->port.lock, flags);
 
 	/* first save CR2 and then disable interrupts */
 	cr = old_cr = lpuart32_read(sport->port.membase + UARTCTRL);
@@ -1675,6 +1695,9 @@ lpuart32_console_write(struct console *c
 		barrier();
 
 	lpuart32_write(old_cr, sport->port.membase + UARTCTRL);
+
+	if (locked)
+		spin_unlock_irqrestore(&sport->port.lock, flags);
 }
 
 /*
@@ -1899,9 +1922,13 @@ static int lpuart_probe(struct platform_
 
 	ret = of_alias_get_id(np, "serial");
 	if (ret < 0) {
-		dev_err(&pdev->dev, "failed to get alias id, errno %d\n", ret);
-		return ret;
+		ret = find_first_zero_bit(linemap, UART_NR);
+		if (ret >= UART_NR) {
+			dev_err(&pdev->dev, "port line is full, add device failed\n");
+			return ret;
+		}
 	}
+	set_bit(ret, linemap);
 	sport->port.line = ret;
 	sport->lpuart32 = of_device_is_compatible(np, "fsl,ls1021a-lpuart");
 
@@ -1983,6 +2010,7 @@ static int lpuart_remove(struct platform
 	struct lpuart_port *sport = platform_get_drvdata(pdev);
 
 	uart_remove_one_port(&lpuart_reg, &sport->port);
+	clear_bit(sport->port.line, linemap);
 
 	clk_disable_unprepare(sport->clk);
 
@@ -2067,12 +2095,10 @@ static int lpuart_resume(struct device *
 
 	if (sport->lpuart_dma_rx_use) {
 		if (sport->port.irq_wake) {
-			if (!lpuart_start_rx_dma(sport)) {
-				sport->lpuart_dma_rx_use = true;
+			if (!lpuart_start_rx_dma(sport))
 				rx_dma_timer_init(sport);
-			} else {
+			else
 				sport->lpuart_dma_rx_use = false;
-			}
 		}
 	}