serial: serial_xen: add DEBUG_UART support
By using a hypervisor call, we can implement DEBUG_UART on xen.
This will allow us to see messages even earlier than serial_init().
Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
diff --git a/drivers/serial/Kconfig b/drivers/serial/Kconfig
index b4805a2..b6ba702 100644
--- a/drivers/serial/Kconfig
+++ b/drivers/serial/Kconfig
@@ -401,11 +401,19 @@
driver will be available until the real driver model serial is
running.
+config DEBUG_UART_XEN
+ bool "XEN Hypervisor Console"
+ depends on XEN_SERIAL
+ help
+ Select this to enable a debug UART using the serial_xen driver. You
+ will not have to provide any parameters to make this work. The driver
+ will be available until the real driver-model serial is running.
+
endchoice
config DEBUG_UART_BASE
hex "Base address of UART"
- depends on DEBUG_UART
+ depends on DEBUG_UART && !DEBUG_UART_XEN
default 0 if DEBUG_UART_SANDBOX
help
This is the base address of your UART for memory-mapped UARTs.
@@ -415,7 +423,7 @@
config DEBUG_UART_CLOCK
int "UART input clock"
- depends on DEBUG_UART
+ depends on DEBUG_UART && !DEBUG_UART_XEN
default 0 if DEBUG_UART_SANDBOX
help
The UART input clock determines the speed of the internal UART
@@ -427,7 +435,7 @@
config DEBUG_UART_SHIFT
int "UART register shift"
- depends on DEBUG_UART
+ depends on DEBUG_UART && !DEBUG_UART_XEN
default 0 if DEBUG_UART
help
Some UARTs (notably ns16550) support different register layouts