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>

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));
 }