pch_uart: Support modem status interrupt

Signed-off-by: Tomoya MORINAGA <tomoya.rohm@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serial/pch_uart.c b/drivers/tty/serial/pch_uart.c
index d035f8f..d11096c 100644 (file)
--- a/drivers/tty/serial/pch_uart.c
+++ b/drivers/tty/serial/pch_uart.c
@@ -1043,10 +1043,15 @@ static irqreturn_t pch_uart_interrupt(int irq, void *dev_id)
        int ret = 0;
        unsigned char iid;
        unsigned long flags;
+       int next = 1;
+       u8 msr;
 
        spin_lock_irqsave(&priv->port.lock, flags);
        handled = 0;
-       while ((iid = pch_uart_hal_get_iid(priv)) > 1) {
+       while (next) {
+               iid = pch_uart_hal_get_iid(priv);
+               if (iid & PCH_UART_IIR_IP) /* No Interrupt */
+                       break;
                switch (iid) {
                case PCH_UART_IID_RLS:  /* Receiver Line Status */
                        lsr = pch_uart_hal_get_line_status(priv);
@@ -1080,12 +1085,18 @@ static irqreturn_t pch_uart_interrupt(int irq, void *dev_id)
                                ret = handle_tx(priv);
                        break;
                case PCH_UART_IID_MS:   /* Modem Status */
-                       ret = PCH_UART_HANDLED_MS_INT;
+                       msr = pch_uart_hal_get_modem(priv);
+                       next = 0; /* MS ir prioirty is the lowest. So, MS ir
+                                    means final interrupt */
+                       if ((msr & UART_MSR_ANY_DELTA) == 0)
+                               break;
+                       ret |= PCH_UART_HANDLED_MS_INT;
                        break;
                default:        /* Never junp to this label */
                        dev_err(priv->port.dev, "%s:iid=%02x (%lu)\n", __func__,
                                iid, jiffies);
                        ret = -1;
+                       next = 0;
                        break;
                }
                handled |= (unsigned int)ret;