Messages in this thread Patch in this message | | | From | Soren Brinkmann <> | Subject | [PATCH 2/9] tty: xuartps: Use spinlock to serialize HW access | Date | Tue, 3 Nov 2015 16:20:43 -0800 |
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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> --- drivers/tty/serial/xilinx_uartps.c | 16 ++++++---------- 1 file changed, 6 insertions(+), 10 deletions(-)
diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c index 50d4082d2354..dc1987f3dc0a 100644 --- a/drivers/tty/serial/xilinx_uartps.c +++ b/drivers/tty/serial/xilinx_uartps.c @@ -947,10 +947,9 @@ 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) @@ -959,8 +958,7 @@ 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; } @@ -968,10 +966,9 @@ static int cdns_uart_poll_get_char(struct uart_port *port) 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 +983,7 @@ 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
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