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Subject[PATCH LINUX v5 5/8] tty: xuartps: Improve startup function
Date
The startup function is supposed to initialize the UART for receiving.
Hence, don't enable the TX part. Also, protect HW accesses with the port
lock.

Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
Reviewed-by: Peter Hurley <peter@hurleysoftware.com>
---
drivers/tty/serial/xilinx_uartps.c | 20 ++++++++++++--------
1 file changed, 12 insertions(+), 8 deletions(-)

diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c
index ef114d7a0623..6ffd3bbe3e18 100644
--- a/drivers/tty/serial/xilinx_uartps.c
+++ b/drivers/tty/serial/xilinx_uartps.c
@@ -758,6 +758,7 @@ static void cdns_uart_set_termios(struct uart_port *port,
*/
static int cdns_uart_startup(struct uart_port *port)
{
+ unsigned long flags;
unsigned int retval = 0, status = 0;

retval = request_irq(port->irq, cdns_uart_isr, 0, CDNS_UART_NAME,
@@ -765,6 +766,8 @@ static int cdns_uart_startup(struct uart_port *port)
if (retval)
return retval;

+ spin_lock_irqsave(&port->lock, flags);
+
/* Disable the TX and RX */
writel(CDNS_UART_CR_TX_DIS | CDNS_UART_CR_RX_DIS,
port->membase + CDNS_UART_CR_OFFSET);
@@ -775,15 +778,14 @@ static int cdns_uart_startup(struct uart_port *port)
writel(CDNS_UART_CR_TXRST | CDNS_UART_CR_RXRST,
port->membase + CDNS_UART_CR_OFFSET);

- status = readl(port->membase + CDNS_UART_CR_OFFSET);
-
- /* Clear the RX disable and TX disable bits and then set the TX enable
- * bit and RX enable bit to enable the transmitter and receiver.
+ /*
+ * Clear the RX disable bit and then set the RX enable bit to enable
+ * the receiver.
*/
- writel((status & ~(CDNS_UART_CR_TX_DIS | CDNS_UART_CR_RX_DIS))
- | (CDNS_UART_CR_TX_EN | CDNS_UART_CR_RX_EN |
- CDNS_UART_CR_STOPBRK),
- port->membase + CDNS_UART_CR_OFFSET);
+ status = readl(port->membase + CDNS_UART_CR_OFFSET);
+ status &= CDNS_UART_CR_RX_DIS;
+ status |= CDNS_UART_CR_RX_EN;
+ writel(status, port->membase + CDNS_UART_CR_OFFSET);

/* Set the Mode Register with normal mode,8 data bits,1 stop bit,
* no parity.
@@ -814,6 +816,8 @@ static int cdns_uart_startup(struct uart_port *port)
CDNS_UART_IXR_RXTRIG | CDNS_UART_IXR_TOUT,
port->membase + CDNS_UART_IER_OFFSET);

+ spin_unlock_irqrestore(&port->lock, flags);
+
return retval;
}

--
2.6.3.3.g9bb996a


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