From: Soren Brinkmann <soren.brinkmann@xilinx.com>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Jiri Slaby <jslaby@suse.com>
Cc: Michal Simek <michal.simek@xilinx.com>,
<linux-serial@vger.kernel.org>,
<linux-arm-kernel@lists.infradead.org>,
<linux-kernel@vger.kernel.org>,
"Soren Brinkmann" <soren.brinkmann@xilinx.com>
Subject: [PATH RESEND v2 02/10] tty: xuartps: Use spinlock to serialize HW access
Date: Thu, 19 Nov 2015 12:02:16 -0800 [thread overview]
Message-ID: <1447963344-16266-3-git-send-email-soren.brinkmann@xilinx.com> (raw)
In-Reply-To: <1447963344-16266-1-git-send-email-soren.brinkmann@xilinx.com>
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>
---
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;
}
--
2.6.3.3.g9bb996a
next prev parent reply other threads:[~2015-11-19 20:15 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-11-19 20:02 [PATH RESEND v2 00/10] tty: xuartps: Fix lock ups Soren Brinkmann
2015-11-19 20:02 ` [PATH RESEND v2 01/10] tty: xuartps: Beautify read-modify writes Soren Brinkmann
2015-11-19 20:02 ` Soren Brinkmann [this message]
2015-11-19 20:02 ` [PATH RESEND v2 03/10] tty: xuartps: Always enable transmitter in start_tx Soren Brinkmann
2015-11-20 12:13 ` Peter Hurley
2015-11-20 15:28 ` Sören Brinkmann
2015-11-20 16:30 ` Peter Hurley
2015-11-20 16:58 ` Sören Brinkmann
2015-11-20 17:16 ` Peter Hurley
2015-11-20 17:29 ` Sören Brinkmann
2015-11-23 7:05 ` Michal Simek
2015-11-23 20:00 ` Peter Hurley
2015-11-24 7:26 ` Michal Simek
2015-11-20 17:05 ` Sören Brinkmann
2015-11-20 17:12 ` Peter Hurley
2015-11-19 20:02 ` [PATH RESEND v2 04/10] tty: xuartps: Clear interrupt status register in shutdown Soren Brinkmann
2015-11-19 20:02 ` [PATH RESEND v2 05/10] tty: xuartps: Improve startup function Soren Brinkmann
2015-11-19 20:02 ` [PATH RESEND v2 06/10] tty: xuartps: Keep lock for whole ISR Soren Brinkmann
2015-11-19 20:02 ` [PATH RESEND v2 07/10] tty: xuartps: Acquire port lock for shutdown Soren Brinkmann
2015-11-19 20:02 ` [PATH RESEND v2 08/10] tty: xuartps: Move RX path into helper function Soren Brinkmann
2015-11-19 20:02 ` [PATH RESEND v2 09/10] tty: xuartps: Only handle RX IRQs when RX is enabled Soren Brinkmann
2015-11-19 20:02 ` [PATH RESEND v2 10/10] tty: xuartps: Cleanup: Reformat if-else Soren Brinkmann
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