[PATCH 1/3][POWERPC][V2] of_serial: Fix possible null dereference.

[John Linn <john.linn@xilinx.com>]

From: Stephen Neuendorffer <stephen.neuendorffer@xilinx.com>

The of_serial driver queries the current-speed property and attempts
to use it to register the custom_divisor property of the uart_port.
However, if current-speed is not set, then this code will dereference
a bad pointer.  The fix is to only set custom_divisor when a
current-speed property appears in the device tree.

Signed-off-by: Stephen Neuendorffer <stephen.neuendorffer@xilinx.com>
Signed-off-by: John Linn <john.linn@xilinx.com>
---
 drivers/serial/of_serial.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)

diff --git a/drivers/serial/of_serial.c b/drivers/serial/of_serial.c
index a64d858..2efb892 100644
--- a/drivers/serial/of_serial.c
+++ b/drivers/serial/of_serial.c
@@ -56,7 +56,9 @@ static int __devinit of_platform_serial_setup(struct of_device *ofdev,
 	port->flags = UPF_SHARE_IRQ | UPF_BOOT_AUTOCONF | UPF_IOREMAP
 		| UPF_FIXED_PORT;
 	port->dev = &ofdev->dev;
-	port->custom_divisor = *clk / (16 * (*spd));
+	/* If current-speed was set, then try not to change it. */
+	if (spd)
+		port->custom_divisor = *clk / (16 * (*spd));
 
 	return 0;
 }
-- 
1.5.2.1