Add 'zImage.dts' and 'zImage.dts_initrd' build rules that automatically
compile and wrap a dts file from arch/powerpc/boot/dts into the zImage file.
The resulting zImage will be arch/powerpc/boot/zImage.dts.<platform> and
arch/powerpc/boot/zImage.dts_initrd.<platform>, respectively.

Having separate rules allows the user to choose whether to include a device
tree--and which device tree--at build time.  This is useful when one Makefile
target builds a zImage that runs on several platforms except for differing
device trees.  By just setting CONFIG_DEVICE_TREE and running "make zImage.dts"
the exact zImage you want is built without Makefile bloat or manually running
the wrapper script.

The dts file is expected to be arch/powerpc/boot/dts/$(CONFIG_DEVICE_TREE)

Signed-off-by: Mark A. Greer <redacted>
---
 arch/powerpc/Makefile      |    2 +-
 arch/powerpc/boot/Makefile |   24 +++++++++++++++++++++++-
 2 files changed, 24 insertions(+), 2 deletions(-)

Index: powerpc/arch/powerpc/boot/Makefile
===================================================================

--- powerpc.orig/arch/powerpc/boot/Makefile
+++ powerpc/arch/powerpc/boot/Makefile

@@ -154,9 +154,27 @@ targets	+= $(image-y) $(initrd-y)
 
 $(addprefix $(obj)/, $(initrd-y)): $(obj)/ramdisk.image.gz
 
+dts-  := $(patsubst zImage%, zImage.dts%, $(image-n) $(image-))
+dts-y := $(patsubst zImage%, zImage.dts%, $(image-y))
+dts-y := $(filter-out $(image-y), $(dts-y))
+targets	+= $(image-y) $(dts-y)
+
+dts_initrd-  := $(patsubst zImage%, zImage.dts_initrd%, $(image-n) $(image-))
+dts_initrd-y := $(patsubst zImage%, zImage.dts_initrd%, $(image-y))
+dts_initrd-y := $(filter-out $(image-y), $(dts_initrd-y))
+targets	+= $(image-y) $(dts_initrd-y)
+
+$(addprefix $(obj)/, $(dts_initrd-y)): $(obj)/ramdisk.image.gz
+
 # Don't put the ramdisk on the pattern rule; when its missing make will try
 # the pattern rule with less dependencies that also matches (even with the
 # hard dependency listed).
+$(obj)/zImage.dts_initrd.%: vmlinux $(wrapperbits)
+	$(call if_changed,wrap,$*,$(dts),,$(obj)/ramdisk.image.gz)
+
+$(obj)/zImage.dts.%: vmlinux $(wrapperbits)
+	$(call if_changed,wrap,$*,$(dts))
+
 $(obj)/zImage.initrd.%: vmlinux $(wrapperbits)
 	$(call if_changed,wrap,$*,,,$(obj)/ramdisk.image.gz)
 

@@ -195,13 +213,17 @@ $(obj)/zImage:		$(addprefix $(obj)/, $(i
 	@rm -f $@; ln $< $@
 $(obj)/zImage.initrd:	$(addprefix $(obj)/, $(initrd-y))
 	@rm -f $@; ln $< $@
+$(obj)/zImage.dts:	$(addprefix $(obj)/, $(dts-y))
+	@rm -f $@; ln $< $@
+$(obj)/zImage.dts_initrd:	$(addprefix $(obj)/, $(dts_initrd-y))
+	@rm -f $@; ln $< $@