serial: msm: add debug UART

Introduce support for early debugging. This relies on the previous stage
bootloader to initialise the UART clocks, when running with U-Boot as
the primary bootloader this feature doesn't work. It will require a way
to configure the clocks before the driver model is available.

Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Reviewed-by: Sumit Garg <sumit.garg@linaro.org>
Signed-off-by: Caleb Connolly <caleb.connolly@linaro.org>
diff --git a/drivers/serial/Kconfig b/drivers/serial/Kconfig
index 26460c4..fbd351a 100644
--- a/drivers/serial/Kconfig
+++ b/drivers/serial/Kconfig
@@ -319,6 +319,14 @@
 	  will need to provide parameters to make this work. The driver will
 	  be available until the real driver-model serial is running.
 
+config DEBUG_UART_MSM
+	bool "Qualcomm QUP UART debug"
+	depends on ARCH_SNAPDRAGON
+	help
+	  Select this to enable a debug UART using the serial_msm driver. You
+	  will need to provide parameters to make this work. The driver will
+	  be available until the real driver-model serial is running.
+
 config DEBUG_UART_MSM_GENI
 	bool "Qualcomm snapdragon"
 	depends on ARCH_SNAPDRAGON