serial/nwpserial: Fix wrong register read address and add interrupt acknowledge.

The receive interrupt routine checks the wrong register if the
receive fifo is empty. Further an explicit interrupt acknowledge
write is introduced. In some circumstances another interrupt was
issued.

Signed-off-by: Benjamin Krill <ben@codiert.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 3 insertions, 1 deletions

diff --git a/drivers/serial/nwpserial.c b/drivers/serial/nwpserial.c
index 32f3eaf0d262..9e150b19d726 100644
--- a/drivers/serial/nwpserial.c
+++ b/drivers/serial/nwpserial.c
@@ -145,11 +145,13 @@ static irqreturn_t nwpserial_interrupt(int irq, void *dev_id)
                 ch = dcr_read(up->dcr_host, UART_RX);
                 if (up->port.ignore_status_mask != NWPSERIAL_STATUS_RXVALID)
                         tty_insert_flip_char(tty, ch, TTY_NORMAL);
-        } while (dcr_read(up->dcr_host, UART_RX) & UART_LSR_DR);
+        } while (dcr_read(up->dcr_host, UART_LSR) & UART_LSR_DR);
 
         tty_flip_buffer_push(tty);
         ret = IRQ_HANDLED;
 
+        /* clear interrupt */
+        dcr_write(up->dcr_host, UART_IIR, 1);
 out:
         spin_unlock(&up->port.lock);
         return ret;