kbuild: consolidate Devicetree dtb build rules

There is nothing arch specific about building dtb files other than their
location under /arch/*/boot/dts/. Keeping each arch aligned is a pain.
The dependencies and supported targets are all slightly different.
Also, a cross-compiler for each arch is needed, but really the host
compiler preprocessor is perfectly fine for building dtbs. Move the
build rules to a common location and remove the arch specific ones. This
is done in a single step to avoid warnings about overriding rules.

The build dependencies had been a mixture of 'scripts' and/or 'prepare'.
These pull in several dependencies some of which need a target compiler
(specifically devicetable-offsets.h) and aren't needed to build dtbs.
All that is really needed is dtc, so adjust the dependencies to only be
dtc.

This change enables support 'dtbs_install' on some arches which were
missing the target.

Acked-by: Will Deacon <will.deacon@arm.com>
Acked-by: Paul Burton <paul.burton@mips.com>
Acked-by: Ley Foon Tan <ley.foon.tan@intel.com>
Acked-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Michal Marek <michal.lkml@markovi.net>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: James Hogan <jhogan@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Chris Zankel <chris@zankel.net>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: linux-kbuild@vger.kernel.org
Cc: linux-snps-arc@lists.infradead.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: uclinux-h8-devel@lists.sourceforge.jp
Cc: linux-mips@linux-mips.org
Cc: nios2-dev@lists.rocketboards.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-xtensa@linux-xtensa.org
Signed-off-by: Rob Herring <robh@kernel.org>

1 files changed, 1 insertions, 11 deletions

diff --git a/arch/xtensa/Makefile b/arch/xtensa/Makefile
index 295c120ed099..13fd3301c517 100644
--- a/arch/xtensa/Makefile
+++ b/arch/xtensa/Makefile
@@ -84,28 +84,18 @@ LIBGCC := $(shell $(CC) $(KBUILD_CFLAGS) -print-libgcc-file-name)
 head-y		:= arch/xtensa/kernel/head.o
 core-y		+= arch/xtensa/kernel/ arch/xtensa/mm/
 core-y		+= $(buildvar) $(buildplf)
+core-y 		+= arch/xtensa/boot/dts/
 
 libs-y		+= arch/xtensa/lib/ $(LIBGCC)
 drivers-$(CONFIG_OPROFILE)	+= arch/xtensa/oprofile/
 
-ifneq ($(CONFIG_BUILTIN_DTB),"")
-core-$(CONFIG_OF) += arch/xtensa/boot/dts/
-endif
-
 boot		:= arch/xtensa/boot
 
 all Image zImage uImage: vmlinux
 	$(Q)$(MAKE) $(build)=$(boot) $@
 
-%.dtb:
-	$(Q)$(MAKE) $(build)=$(boot)/dts $(boot)/dts/$@
-
-dtbs: scripts
-	$(Q)$(MAKE) $(build)=$(boot)/dts
-
 define archhelp
   @echo '* Image       - Kernel ELF image with reset vector'
   @echo '* zImage      - Compressed kernel image (arch/xtensa/boot/images/zImage.*)'
   @echo '* uImage      - U-Boot wrapped image'
-  @echo '  dtbs        - Build device tree blobs for enabled boards'
 endef