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Commit f0f54a80 authored by Soren Brinkmann's avatar Soren Brinkmann Committed by Greg Kroah-Hartman
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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: default avatarSoren Brinkmann <soren.brinkmann@xilinx.com>
Reviewed-by: default avatarPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent e3538c37

drivers/tty/serial/xilinx_uartps.c

+6 −12
Original line number Original line Diff line number Diff line
@@ -945,12 +945,10 @@ static void cdns_uart_set_mctrl(struct uart_port *port, unsigned int mctrl) 
#ifdef CONFIG_CONSOLE_POLL

#ifdef CONFIG_CONSOLE_POLL

static int cdns_uart_poll_get_char(struct uart_port *port)

static int cdns_uart_poll_get_char(struct uart_port *port)

{

{

	u32 imr;

	int c;

	int c;

	unsigned long flags;





	/* Disable all interrupts */

	spin_lock_irqsave(&port->lock, flags);

	imr = readl(port->membase + CDNS_UART_IMR_OFFSET);

	writel(imr, port->membase + CDNS_UART_IDR_OFFSET);





	/* Check if FIFO is empty */

	/* Check if FIFO is empty */

	if (readl(port->membase + CDNS_UART_SR_OFFSET) & CDNS_UART_SR_RXEMPTY)

	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(

		c = (unsigned char) readl(

					port->membase + CDNS_UART_FIFO_OFFSET);

					port->membase + CDNS_UART_FIFO_OFFSET);





	/* Enable interrupts */

	spin_unlock_irqrestore(&port->lock, flags);

	writel(imr, port->membase + CDNS_UART_IER_OFFSET);





	return c;

	return c;

}

}





static void cdns_uart_poll_put_char(struct uart_port *port, unsigned char c)

static void cdns_uart_poll_put_char(struct uart_port *port, unsigned char c)

{

{

	u32 imr;

	unsigned long flags;





	/* Disable all interrupts */

	spin_lock_irqsave(&port->lock, flags);

	imr = readl(port->membase + CDNS_UART_IMR_OFFSET);

	writel(imr, port->membase + CDNS_UART_IDR_OFFSET);





	/* Wait until FIFO is empty */

	/* Wait until FIFO is empty */

	while (!(readl(port->membase + CDNS_UART_SR_OFFSET) &

	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))

				CDNS_UART_SR_TXEMPTY))

		cpu_relax();

		cpu_relax();





	/* Enable interrupts */

	spin_unlock_irqrestore(&port->lock, flags);

	writel(imr, port->membase + CDNS_UART_IER_OFFSET);





	return;

	return;

}

}