[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <1446708079-1105-3-git-send-email-soren.brinkmann@xilinx.com>
Date: Wed, 4 Nov 2015 23:21:11 -0800
From: Soren Brinkmann <soren.brinkmann@...inx.com>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Jiri Slaby <jslaby@...e.com>
CC: Michal Simek <michal.simek@...inx.com>,
<linux-serial@...r.kernel.org>,
<linux-arm-kernel@...ts.infradead.org>,
<linux-kernel@...r.kernel.org>,
"Soren Brinkmann" <soren.brinkmann@...inx.com>
Subject: [PATCH v2 02/10] 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@...inx.com>
---
v2:
- remove unused variable
---
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 50d4082d2354..2c98c357d9a0 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;
}
--
2.6.2.3.ga463a5b
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists