[PATCH v5 2/2] ARM: uncompress debug support for multiplatform build

[Shawn Guo]

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 at linaro.org>
Acked-by: Olof Johansson <olof at lixom.net>
Acked-by: Tony Lindgren <tony at atomide.com>
---
Changes since v4:
 - Mark DEBUG_TEGRA_UART as another exception, as the debug code refers
   to tegra_uart_config which is only accessible in kernel.

 arch/arm/Kconfig.debug              |    6 ++++++
 arch/arm/boot/compressed/Makefile   |    3 +++
 arch/arm/boot/compressed/debug.S    |   12 ++++++++++++
 arch/arm/include/debug/uncompress.h |    4 ++++
 4 files changed, 25 insertions(+)
 create mode 100644 arch/arm/boot/compressed/debug.S

diff --git a/arch/arm/Kconfig.debug b/arch/arm/Kconfig.debug
index fc54a5b..7aa30e4 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 5cad8a6..e3238bc 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 0000000..6e8382d
--- /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 e19955d..0e2949b 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) {}
-- 
1.7.9.5