[PATCH V7 1/7] kbuild: centralize .dts->.dtb rule

[Stephen Warren]

From: Stephen Warren <swarren at nvidia.com>

All architectures that use cmd_dtc do so in almost the same way. Create
a central build rule to avoid duplication. The one difference is that
most current uses of dtc build $(obj)/%.dtb from $(src)/dts/%.dts rather
than building the .dtb in the same directory as the .dts file. This
difference will be eliminated arch-by-arch in future patches.

MIPS is the exception here; it already uses the exact same rule as the
new common rule, so the duplicate is removed in this patch to avoid any
conflict. arch/mips changes courtesy of Ralf Baechle.

Update Documentation/kbuild to remove the explicit call to cmd_dtc from
the example, now that the rule exists in a centralized location.

Cc: Arnd Bergmann <arnd at arndb.de>
Cc: linux-arm-kernel at lists.infradead.org
Cc: Olof Johansson <olof at lixom.net>
Cc: Russell King <linux at arm.linux.org.uk>
Cc: Catalin Marinas <catalin.marinas at arm.com>
Cc: Jonas Bonn <jonas at southpole.se>
Cc: linux at lists.openrisc.net
Cc: Aurelien Jacquiot <a-jacquiot at ti.com>
Cc: linux-c6x-dev at linux-c6x.org
Cc: Mark Salter <msalter at redhat.com>
Cc: Michal Simek <monstr at monstr.eu>
Cc: microblaze-uclinux at itee.uq.edu.au
Cc: Chris Zankel <chris at zankel.net>
Cc: linux-xtensa at linux-xtensa.org
Cc: Max Filippov <jcmvbkbc at gmail.com>
Signed-off-by: Ralf Baechle <ralf at linux-mips.org>
Signed-off-by: Stephen Warren <swarren at nvidia.com>
---
This is based on next-20121126.

I've split out this dtc rule cleanup as a separate patch series.
Hopefully it can be applied without too much controversy, then I'll move
back to discussing running cpp over *.dts.

v7:
* Build *.dtb from *.dts not src/*.dts.
* Removed all arch/ updates except MIPS.
v6: Added arch/{arm64,microblaze,mips} updates.
v5: Updated Documentation/kbuild.
v4: No change.
v3: No change.
v2: New patch.
---
 Documentation/kbuild/makefiles.txt |   15 ++++++++-------
 arch/mips/cavium-octeon/Makefile   |    3 ---
 arch/mips/lantiq/dts/Makefile      |    3 ---
 arch/mips/netlogic/dts/Makefile    |    3 ---
 scripts/Makefile.lib               |    3 +++
 5 files changed, 11 insertions(+), 16 deletions(-)

diff --git a/Documentation/kbuild/makefiles.txt b/Documentation/kbuild/makefiles.txt
index ec9ae67..14c3f4f 100644
--- a/Documentation/kbuild/makefiles.txt
+++ b/Documentation/kbuild/makefiles.txt
@@ -1175,15 +1175,16 @@ When kbuild executes, the following steps are followed (roughly):
 	in an init section in the image. Platform code *must* copy the
 	blob to non-init memory prior to calling unflatten_device_tree().
 
-	Example:
-		#arch/x86/platform/ce4100/Makefile
-		clean-files := *dtb.S
+	To use this command, simply add *.dtb into obj-y or targets, or make
+	some other target depend on %.dtb
 
-		DTC_FLAGS := -p 1024
-		obj-y += foo.dtb.o
+	A central rule exists to create $(obj)/%.dtb from $(src)/%.dts;
+	architecture Makefiles do no need to explicitly write out that rule.
 
-		$(obj)/%.dtb: $(src)/%.dts
-			$(call cmd,dtc)
+	Example:
+		targets += $(dtb-y)
+		clean-files += *.dtb
+		DTC_FLAGS ?= -p 1024
 
 --- 6.8 Custom kbuild commands
 
diff --git a/arch/mips/cavium-octeon/Makefile b/arch/mips/cavium-octeon/Makefile
index bc96e29..6e927cf 100644
--- a/arch/mips/cavium-octeon/Makefile
+++ b/arch/mips/cavium-octeon/Makefile
@@ -24,9 +24,6 @@ DTB_FILES = $(patsubst %.dts, %.dtb, $(DTS_FILES))
 
 obj-y += $(patsubst %.dts, %.dtb.o, $(DTS_FILES))
 
-$(obj)/%.dtb: $(src)/%.dts FORCE
-	$(call if_changed_dep,dtc)
-
 # Let's keep the .dtb files around in case we want to look at them.
 .SECONDARY:  $(addprefix $(obj)/, $(DTB_FILES))
 
diff --git a/arch/mips/lantiq/dts/Makefile b/arch/mips/lantiq/dts/Makefile
index 674fca4..6fa72dd 100644
--- a/arch/mips/lantiq/dts/Makefile
+++ b/arch/mips/lantiq/dts/Makefile
@@ -1,4 +1 @@
 obj-$(CONFIG_DT_EASY50712) := easy50712.dtb.o
-
-$(obj)/%.dtb: $(obj)/%.dts
-	$(call if_changed,dtc)
diff --git a/arch/mips/netlogic/dts/Makefile b/arch/mips/netlogic/dts/Makefile
index 67ae3fe2..d117d46 100644
--- a/arch/mips/netlogic/dts/Makefile
+++ b/arch/mips/netlogic/dts/Makefile
@@ -1,4 +1 @@
 obj-$(CONFIG_DT_XLP_EVP) := xlp_evp.dtb.o
-
-$(obj)/%.dtb: $(obj)/%.dts
-	$(call if_changed,dtc)
diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
index 0be6f11..bdf42fd 100644
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib
@@ -266,6 +266,9 @@ $(obj)/%.dtb.S: $(obj)/%.dtb
 quiet_cmd_dtc = DTC     $@
 cmd_dtc = $(objtree)/scripts/dtc/dtc -O dtb -o $@ -b 0 $(DTC_FLAGS) -d $(depfile) $<
 
+$(obj)/%.dtb: $(src)/%.dts FORCE
+	$(call if_changed_dep,dtc)
+
 # Bzip2
 # ---------------------------------------------------------------------------
 
-- 
1.7.10.4