From: Shubhrajyoti Datta <shubhrajyoti.datta@xilinx.com>
Date: Fri, 29 Jul 2022 11:47:47 +0000 (+0530)
Subject: tty: xilinx_uartps: Add timeout waiting for loop
X-Git-Tag: baikal/mips/sdk6.1~4689^2~98
X-Git-Url: https://git.baikalelectronics.ru/?a=commitdiff_plain;h=9e3ce605ff121f9dc8a03e4c53a9504545b483bb;p=kernel.git

tty: xilinx_uartps: Add timeout waiting for loop

There is a potential infinite loop while waiting for the
the TXFULL to deassert. Adds the error message and timeout to
avoid infinite loop if it fails to get the TX fifo not full.

Signed-off-by: Shubhrajyoti Datta <shubhrajyoti.datta@xilinx.com>
Link: https://lore.kernel.org/r/20220729114748.18332-7-shubhrajyoti.datta@xilinx.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c
index d1aa44febaea7..da83ae6df1e08 100644
--- a/drivers/tty/serial/xilinx_uartps.c
+++ b/drivers/tty/serial/xilinx_uartps.c
@@ -1147,8 +1147,20 @@ static void cdns_uart_console_putchar(struct uart_port *port, unsigned char ch)
 		}
 		cpu_relax();
 	}
-	while (readl(port->membase + CDNS_UART_SR) & CDNS_UART_SR_TXFULL)
+
+	timeout = jiffies + msecs_to_jiffies(1000);
+	while (1) {
+		ctrl_reg = readl(port->membase + CDNS_UART_SR);
+
+		if (!(ctrl_reg & CDNS_UART_SR_TXFULL))
+			break;
+		if (time_after(jiffies, timeout)) {
+			dev_warn(port->dev,
+				 "timeout waiting for TX fifo\n");
+			return;
+		}
 		cpu_relax();
+	}
 	writel(ch, port->membase + CDNS_UART_FIFO);
 }