MIPS: Allow platforms to specify the decompressor load address

Platforms which use raw zboot images may need to link the image at
a fixed address if there is no other way to communicate the load
address to the bootloader.  Allow the per-platform Kbuild files
to specify an optional zboot image load address (zload-y) and fall
back to calc_vmlinuz_load_addr if unset.

Signed-off-by: Andrew Bresticker <abrestic@chromium.org>
Cc: Lars-Peter Clausen <lars@metafoo.de>
Cc: devicetree@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Cc: Andrew Bresticker <abrestic@chromium.org>
Cc: Ezequiel Garcia <ezequiel.garcia@imgtec.com>
Cc: James Hartley <james.hartley@imgtec.com>
Cc: James Hogan <james.hogan@imgtec.com>
Patchwork: https://patchwork.linux-mips.org/patch/9566/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/boot/compressed/Makefile

@@ -12,6 +12,8 @@
 # Author: Wu Zhangjin <wuzhangjin@gmail.com>
 #
 
+include $(srctree)/arch/mips/Kbuild.platforms
+
 # set the default size of the mallocing area for decompressing
 BOOT_HEAP_SIZE := 0x400000
 
@@ -66,8 +68,8 @@ $(obj)/piggy.o: $(obj)/dummy.o $(obj)/vmlinux.bin.z FORCE
 # Calculate the load address of the compressed kernel image
 hostprogs-y := calc_vmlinuz_load_addr
 
-ifeq ($(CONFIG_MACH_JZ4740),y)
-VMLINUZ_LOAD_ADDRESS := 0x80600000
+ifneq ($(zload-y),)
+VMLINUZ_LOAD_ADDRESS := $(zload-y)
 else
 VMLINUZ_LOAD_ADDRESS = $(shell $(obj)/calc_vmlinuz_load_addr \
 		$(obj)/vmlinux.bin $(VMLINUX_LOAD_ADDRESS))

arch/mips/jz4740/Platform

@@ -1,3 +1,4 @@
 platform-$(CONFIG_MACH_JZ4740)	+= jz4740/
 cflags-$(CONFIG_MACH_JZ4740)	+= -I$(srctree)/arch/mips/include/asm/mach-jz4740
 load-$(CONFIG_MACH_JZ4740)	+= 0xffffffff80010000
+zload-$(CONFIG_MACH_JZ4740)	+= 0xffffffff80600000