ARM: 7672/1: uncompress debug support for multiplatform build

Instead of giving zero support of uncompress debug for multiplatform
build, the patch turns uncompress debug into one part of DEBUG_LL
support.  When DEBUG_LL is turned on for a particular platform,
uncompress debug works too for that platform.

OMAP and Tegra are exceptions here.  OMAP low-level debug code places
data in the .data section, and that is not allowed in decompressor.
And Tegra code has reference to variable that's unavailable in
decompressor but only in kernel.  That's why Kconfig symbol
DEBUG_UNCOMPRESS controlling multiplatform uncompress debug support is
defined with !DEBUG_OMAP2PLUS_UART && !DEBUG_TEGRA_UART.

It creates arch/arm/boot/compressed/debug.S with CONFIG_DEBUG_LL_INCLUDE
included there, implements a generic putc() using those macros, which
will be built when DEBUG_UNCOMPRESS is defined.
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/Kconfig.debug

@@ -601,6 +601,12 @@ config DEBUG_LL_INCLUDE
 	default "debug/zynq.S" if DEBUG_ZYNQ_UART0 || DEBUG_ZYNQ_UART1
 	default "mach/debug-macro.S"
 
+config DEBUG_UNCOMPRESS
+	bool
+	default y if ARCH_MULTIPLATFORM && DEBUG_LL && \
+		     !DEBUG_OMAP2PLUS_UART && \
+		     !DEBUG_TEGRA_UART
+
 config UNCOMPRESS_INCLUDE
 	string
 	default "debug/uncompress.h" if ARCH_MULTIPLATFORM

arch/arm/boot/compressed/Makefile

@@ -24,6 +24,9 @@ endif
 AFLAGS_head.o += -DTEXT_OFFSET=$(TEXT_OFFSET)
 HEAD	= head.o
 OBJS	+= misc.o decompress.o
+ifeq ($(CONFIG_DEBUG_UNCOMPRESS),y)
+OBJS	+= debug.o
+endif
 FONTC	= $(srctree)/drivers/video/console/font_acorn_8x8.c
 
 # string library code (-Os is enforced to keep it much smaller)

arch/arm/boot/compressed/debug.S

+#include <linux/linkage.h>
+#include <asm/assembler.h>
+
+#include CONFIG_DEBUG_LL_INCLUDE
+
+ENTRY(putc)
+	addruart r1, r2, r3
+	waituart r3, r1
+	senduart r0, r1
+	busyuart r3, r1
+	mov	 pc, lr
+ENDPROC(putc)

arch/arm/include/debug/uncompress.h

+#ifdef CONFIG_DEBUG_UNCOMPRESS
+extern void putc(int c);
+#else
 static inline void putc(int c) {}
+#endif
 static inline void flush(void) {}
 static inline void arch_decomp_setup(void) {}