From mboxrd@z Thu Jan 1 00:00:00 1970 From: Soren Brinkmann Subject: [PATCH v2 02/10] tty: xuartps: Use spinlock to serialize HW access Date: Wed, 4 Nov 2015 23:21:11 -0800 Message-ID: <1446708079-1105-3-git-send-email-soren.brinkmann@xilinx.com> References: <1446708079-1105-1-git-send-email-soren.brinkmann@xilinx.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1446708079-1105-1-git-send-email-soren.brinkmann@xilinx.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=m.gmane.org@lists.infradead.org To: Greg Kroah-Hartman , Jiri Slaby Cc: linux-arm-kernel@lists.infradead.org, Soren Brinkmann , Michal Simek , linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org List-Id: linux-serial@vger.kernel.org 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 --- 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