atmel_serial: use existing console options only if BRG is running

If BRGR is zero, the baud rate generator isn't running, so the boot loader
can't have initialized the port.

Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.com>
Acked-by: Andrew Victor <linux@maxim.org.za>
Tested-by: Marc Pignat <marc.pignat@hevs.ch>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 7 insertions, 8 deletions

diff --git a/drivers/serial/atmel_serial.c b/drivers/serial/atmel_serial.c
index 4d1ccc2b762d..0b7b2743b996 100644
--- a/drivers/serial/atmel_serial.c
+++ b/drivers/serial/atmel_serial.c
@@ -834,13 +834,13 @@ static void __init atmel_console_get_options(struct uart_port *port, int *baud,
 {
         unsigned int mr, quot;
 
-// TODO: CR is a write-only register
-//      unsigned int cr;
-//
-//      cr = UART_GET_CR(port) & (ATMEL_US_RXEN | ATMEL_US_TXEN);
-//      if (cr == (ATMEL_US_RXEN | ATMEL_US_TXEN)) {
-//              /* ok, the port was enabled */
-//      }
+        /*
+         * If the baud rate generator isn't running, the port wasn't
+         * initialized by the boot loader.
+         */
+        quot = UART_GET_BRGR(port);
+        if (!quot)
+                return;
 
         mr = UART_GET_MR(port) & ATMEL_US_CHRL;
         if (mr == ATMEL_US_CHRL_8)
@@ -860,7 +860,6 @@ static void __init atmel_console_get_options(struct uart_port *port, int *baud,
          * lower than one of those, as it would make us fall through
          * to a much lower baud rate than we really want.
          */
-        quot = UART_GET_BRGR(port);
         *baud = port->uartclk / (16 * (quot - 1));
 }