[PATCH 2/3] MIPS: zboot: Add support for serial debug using the PROM

[Alban Bedel <albeu@free.fr>]

As most platforms implement the PROM serial interface prom_putchar()
add a simple bridge to allow re-using this code for zboot.

Signed-off-by: Alban Bedel <albeu@free.fr>
---
 arch/mips/Kconfig                     | 4 ++++
 arch/mips/boot/compressed/Makefile    | 1 +
 arch/mips/boot/compressed/uart-prom.c | 7 +++++++
 3 files changed, 12 insertions(+)
 create mode 100644 arch/mips/boot/compressed/uart-prom.c

diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 71683a8..ef1d665 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -1756,6 +1756,10 @@ config SYS_SUPPORTS_ZBOOT_UART16550
 	bool
 	select SYS_SUPPORTS_ZBOOT
 
+config SYS_SUPPORTS_ZBOOT_UART_PROM
+	bool
+	select SYS_SUPPORTS_ZBOOT
+
 config CPU_LOONGSON2
 	bool
 	select CPU_SUPPORTS_32BIT_KERNEL
diff --git a/arch/mips/boot/compressed/Makefile b/arch/mips/boot/compressed/Makefile
index e66b2c6..4eff1ef 100644
--- a/arch/mips/boot/compressed/Makefile
+++ b/arch/mips/boot/compressed/Makefile
@@ -35,6 +35,7 @@ vmlinuzobjs-y := $(obj)/head.o $(obj)/decompress.o $(obj)/string.o
 ifdef CONFIG_DEBUG_ZBOOT
 vmlinuzobjs-$(CONFIG_DEBUG_ZBOOT)		   += $(obj)/dbg.o
 vmlinuzobjs-$(CONFIG_SYS_SUPPORTS_ZBOOT_UART16550) += $(obj)/uart-16550.o
+vmlinuzobjs-$(CONFIG_SYS_SUPPORTS_ZBOOT_UART_PROM) += $(obj)/uart-prom.o
 vmlinuzobjs-$(CONFIG_MIPS_ALCHEMY)		   += $(obj)/uart-alchemy.o
 endif
 
diff --git a/arch/mips/boot/compressed/uart-prom.c b/arch/mips/boot/compressed/uart-prom.c
new file mode 100644
index 0000000..1c3d51b
--- /dev/null
+++ b/arch/mips/boot/compressed/uart-prom.c
@@ -0,0 +1,7 @@
+
+extern void prom_putchar(unsigned char ch);
+
+void putc(char c)
+{
+	prom_putchar(c);
+}
-- 
2.0.0