[POWERPC] Fix default clock for udbg_16550

This patch makes it possible to provide 0 as the clock value for
udbg_16550, making it default to the standard 1.8432Mhz clock

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

1 files changed, 5 insertions, 1 deletions

diff --git a/arch/powerpc/kernel/udbg_16550.c b/arch/powerpc/kernel/udbg_16550.c
index 0835b4841de..2d17f2b8eda 100644
--- a/arch/powerpc/kernel/udbg_16550.c
+++ b/arch/powerpc/kernel/udbg_16550.c
@@ -81,10 +81,14 @@ static int udbg_550_getc(void)
 void udbg_init_uart(void __iomem *comport, unsigned int speed,
                     unsigned int clock)
 {
-        unsigned int dll, base_bauds = clock / 16;
+        unsigned int dll, base_bauds;
 
+        if (clock == 0)
+                clock = 1843200;
         if (speed == 0)
                 speed = 9600;
+
+        base_bauds = clock / 16;
         dll = base_bauds / speed;
 
         if (comport) {