tty: serial: imx: add lock for registers save/restore

In noirq suspend/resume stage with no_console_suspend enabled,
imx_uart_console_write() may be called to print out log_buf
message by printk(), so there will be race condition between
imx_uart_console_write() and imx_uart_save/restore_context(),
need to add lock to protect the registers save/restore operations.

Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index 3069ee93583e949c427658ffb87163d4e3850dbb..2634272ad0fb35833e8f4a531b0f46034391c27a 100644 (file)
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -2371,8 +2371,13 @@ static int imx_uart_remove(struct platform_device *pdev)
 
 static void imx_uart_restore_context(struct imx_port *sport)
 {
-       if (!sport->context_saved)
+       unsigned long flags;
+
+       spin_lock_irqsave(&sport->port.lock, flags);
+       if (!sport->context_saved) {
+               spin_unlock_irqrestore(&sport->port.lock, flags);
                return;
+       }
 
        imx_uart_writel(sport, sport->saved_reg[4], UFCR);
        imx_uart_writel(sport, sport->saved_reg[5], UESC);
@@ -2385,11 +2390,15 @@ static void imx_uart_restore_context(struct imx_port *sport)
        imx_uart_writel(sport, sport->saved_reg[2], UCR3);
        imx_uart_writel(sport, sport->saved_reg[3], UCR4);
        sport->context_saved = false;
+       spin_unlock_irqrestore(&sport->port.lock, flags);
 }
 
 static void imx_uart_save_context(struct imx_port *sport)
 {
+       unsigned long flags;
+
        /* Save necessary regs */
+       spin_lock_irqsave(&sport->port.lock, flags);
        sport->saved_reg[0] = imx_uart_readl(sport, UCR1);
        sport->saved_reg[1] = imx_uart_readl(sport, UCR2);
        sport->saved_reg[2] = imx_uart_readl(sport, UCR3);
@@ -2401,6 +2410,7 @@ static void imx_uart_save_context(struct imx_port *sport)
        sport->saved_reg[8] = imx_uart_readl(sport, UBMR);
        sport->saved_reg[9] = imx_uart_readl(sport, IMX21_UTS);
        sport->context_saved = true;
+       spin_unlock_irqrestore(&sport->port.lock, flags);
 }
 
 static void imx_uart_enable_wakeup(struct imx_port *sport, bool on)