From f0f54a806b2df97485519a7c4ebc45feed08a306 Mon Sep 17 00:00:00 2001
From: Soren Brinkmann <soren.brinkmann@xilinx.com>
Date: Sat, 26 Dec 2015 02:43:50 -0800
Subject: [PATCH] tty: xuartps: Use spinlock to serialize HW access
Instead of disabling the IRQ, use the spin lock to serialize accesses to
the HW. This protects the driver from interference of non-IRQ callbacks
with each other and makes the driver more consistent in its
serialization method.
Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
Reviewed-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/tty/serial/xilinx_uartps.c | 18 ++++++------------
1 file changed, 6 insertions(+), 12 deletions(-)
diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c
index 50d4082d2354c..2c98c357d9a09 100644
--- a/drivers/tty/serial/xilinx_uartps.c
+++ b/drivers/tty/serial/xilinx_uartps.c
@@ -945,12 +945,10 @@ static void cdns_uart_set_mctrl(struct uart_port *port, unsigned int mctrl)
#ifdef CONFIG_CONSOLE_POLL
static int cdns_uart_poll_get_char(struct uart_port *port)
{
- u32 imr;
int c;
+ unsigned long flags;
- /* Disable all interrupts */
- imr = readl(port->membase + CDNS_UART_IMR_OFFSET);
- writel(imr, port->membase + CDNS_UART_IDR_OFFSET);
+ spin_lock_irqsave(&port->lock, flags);
/* Check if FIFO is empty */
if (readl(port->membase + CDNS_UART_SR_OFFSET) & CDNS_UART_SR_RXEMPTY)
@@ -959,19 +957,16 @@ static int cdns_uart_poll_get_char(struct uart_port *port)
c = (unsigned char) readl(
port->membase + CDNS_UART_FIFO_OFFSET);
- /* Enable interrupts */
- writel(imr, port->membase + CDNS_UART_IER_OFFSET);
+ spin_unlock_irqrestore(&port->lock, flags);
return c;
}
static void cdns_uart_poll_put_char(struct uart_port *port, unsigned char c)
{
- u32 imr;
+ unsigned long flags;
- /* Disable all interrupts */
- imr = readl(port->membase + CDNS_UART_IMR_OFFSET);
- writel(imr, port->membase + CDNS_UART_IDR_OFFSET);
+ spin_lock_irqsave(&port->lock, flags);
/* Wait until FIFO is empty */
while (!(readl(port->membase + CDNS_UART_SR_OFFSET) &
@@ -986,8 +981,7 @@ static void cdns_uart_poll_put_char(struct uart_port *port, unsigned char c)
CDNS_UART_SR_TXEMPTY))
cpu_relax();
- /* Enable interrupts */
- writel(imr, port->membase + CDNS_UART_IER_OFFSET);
+ spin_unlock_irqrestore(&port->lock, flags);
return;
}
--
2.30.2