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>

4 files changed, 25 insertions, 0 deletions

diff --git a/arch/arm/Kconfig.debug b/arch/arm/Kconfig.debug
index fc54a5bcf5ab..7aa30e43cb8e 100644
--- a/arch/arm/Kconfig.debug
+++ b/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
diff --git a/arch/arm/boot/compressed/Makefile b/arch/arm/boot/compressed/Makefile
index afed28e37ea5..3580d57ea218 100644
--- a/arch/arm/boot/compressed/Makefile
+++ b/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)
diff --git a/arch/arm/boot/compressed/debug.S b/arch/arm/boot/compressed/debug.S
new file mode 100644
index 000000000000..6e8382d5b7a4
--- /dev/null
+++ b/arch/arm/boot/compressed/debug.S
@@ -0,0 +1,12 @@
+#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)
diff --git a/arch/arm/include/debug/uncompress.h b/arch/arm/include/debug/uncompress.h
index e19955d9e02e..0e2949b0fae9 100644
--- a/arch/arm/include/debug/uncompress.h
+++ b/arch/arm/include/debug/uncompress.h
@@ -1,3 +1,7 @@
+#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) {}