tty: xuartps: Refactor IRQ handling

The system could deadlock handling RX IRQs when RX-related IRQ
conditions became true while the receiver was disabled. To avoid this,
enable/disable the RX/TX IRQs together with the receiver/transmitter.

Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c
index 5da1c51..a0039cb 100644 (file)
--- a/drivers/tty/serial/xilinx_uartps.c
+++ b/drivers/tty/serial/xilinx_uartps.c
@@ -126,6 +126,10 @@ MODULE_PARM_DESC(rx_timeout, "Rx timeout, 1-255");
 #define CDNS_UART_IXR_RXEMPTY  0x00000002 /* RX FIFO empty interrupt. */
 #define CDNS_UART_IXR_MASK     0x00001FFF /* Valid bit mask */
 
+#define CDNS_UART_RX_IRQS      (CDNS_UART_IXR_PARITY | CDNS_UART_IXR_FRAMING | \
+                                CDNS_UART_IXR_OVERRUN | CDNS_UART_IXR_RXTRIG | \
+                                CDNS_UART_IXR_TOUT)
+
 /* Goes in read_status_mask for break detection as the HW doesn't do it*/
 #define CDNS_UART_IXR_BRK      0x80000000
 
@@ -272,7 +276,8 @@ static irqreturn_t cdns_uart_isr(int irq, void *dev_id)
         */
        isrstatus = readl(port->membase + CDNS_UART_ISR_OFFSET);
 
-       cdns_uart_handle_rx(port, isrstatus);
+       if (isrstatus & CDNS_UART_RX_IRQS)
+               cdns_uart_handle_rx(port, isrstatus);
 
        /* Dispatch an appropriate handler */
        if ((isrstatus & CDNS_UART_IXR_TXEMPTY) == CDNS_UART_IXR_TXEMPTY) {
@@ -580,9 +585,12 @@ static void cdns_uart_stop_rx(struct uart_port *port)
 {
        unsigned int regval;
 
+       /* Disable RX IRQs */
+       writel(CDNS_UART_RX_IRQS, port->membase + CDNS_UART_IDR_OFFSET);
+
+       /* Disable the receiver */
        regval = readl(port->membase + CDNS_UART_CR_OFFSET);
        regval |= CDNS_UART_CR_RX_DIS;
-       /* Disable the receiver */
        writel(regval, port->membase + CDNS_UART_CR_OFFSET);
 }
 
@@ -820,10 +828,7 @@ static int cdns_uart_startup(struct uart_port *port)
        }
 
        /* Set the Interrupt Registers with desired interrupts */
-       writel(CDNS_UART_IXR_TXEMPTY | CDNS_UART_IXR_PARITY |
-               CDNS_UART_IXR_FRAMING | CDNS_UART_IXR_OVERRUN |
-               CDNS_UART_IXR_RXTRIG | CDNS_UART_IXR_TOUT,
-               port->membase + CDNS_UART_IER_OFFSET);
+       writel(CDNS_UART_RX_IRQS, port->membase + CDNS_UART_IER_OFFSET);
 
        return 0;
 }