Add support for building DT overlays (%.dtbo). The overlay's source file
will have the usual extension, i.e. .dts, though the blob will have
.dtbo extension to distinguish it from normal blobs.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
 .gitignore               | 3 +--
 Makefile                 | 4 ++--
 scripts/Makefile.dtbinst | 3 +++
 scripts/Makefile.lib     | 4 +++-
 4 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/.gitignore b/.gitignore
index d01cda8e1177..0458c36f3cb2 100644
--- a/.gitignore
+++ b/.gitignore

@@ -17,8 +17,7 @@
 *.bz2
 *.c.[012]*.*
 *.dt.yaml
-*.dtb
-*.dtb.S
+*.dtb*
 *.dwo
 *.elf
 *.gcno

diff --git a/Makefile b/Makefile
index 9e73f82e0d86..b84f5e0b46ab 100644
--- a/Makefile
+++ b/Makefile

@@ -1334,7 +1334,7 @@ endif
 
 ifneq ($(dtstree),)
 
-%.dtb: include/config/kernel.release scripts_dtc
+%.dtb %.dtbo: include/config/kernel.release scripts_dtc
 	$(Q)$(MAKE) $(build)=$(dtstree) $(dtstree)/$@
 
 PHONY += dtbs dtbs_install dtbs_check

@@ -1816,7 +1816,7 @@ clean: $(clean-dirs)
 	@find $(if $(KBUILD_EXTMOD), $(KBUILD_EXTMOD), .) $(RCS_FIND_IGNORE) \
 		\( -name '*.[aios]' -o -name '*.ko' -o -name '.*.cmd' \
 		-o -name '*.ko.*' \
-		-o -name '*.dtb' -o -name '*.dtb.S' -o -name '*.dt.yaml' \
+		-o -name '*.dtb' -o -name '*.dtbo' -o -name '*.dtb.S' -o -name '*.dt.yaml' \
 		-o -name '*.dwo' -o -name '*.lst' \
 		-o -name '*.su' -o -name '*.mod' \
 		-o -name '.*.d' -o -name '.*.tmp' -o -name '*.mod.c' \

diff --git a/scripts/Makefile.dtbinst b/scripts/Makefile.dtbinst
index 50d580d77ae9..ba01f5ba2517 100644
--- a/scripts/Makefile.dtbinst
+++ b/scripts/Makefile.dtbinst

@@ -29,6 +29,9 @@ quiet_cmd_dtb_install = INSTALL $@
 $(dst)/%.dtb: $(obj)/%.dtb
 	$(call cmd,dtb_install)
 
+$(dst)/%.dtbo: $(obj)/%.dtbo
+	$(call cmd,dtb_install)
+
 PHONY += $(subdirs)
 $(subdirs):
 	$(Q)$(MAKE) $(dtbinst)=$@ dst=$(patsubst $(obj)/%,$(dst)/%,$@)

diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
index 213677a5ed33..30bc0a8e0087 100644
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib

@@ -86,7 +86,9 @@ extra-$(CONFIG_OF_ALL_DTBS)	+= $(dtb-)
 
 ifneq ($(CHECK_DTBS),)
 extra-y += $(patsubst %.dtb,%.dt.yaml, $(dtb-y))
+extra-y += $(patsubst %.dtbo,%.dt.yaml, $(dtb-y))
 extra-$(CONFIG_OF_ALL_DTBS) += $(patsubst %.dtb,%.dt.yaml, $(dtb-))
+extra-$(CONFIG_OF_ALL_DTBS) += $(patsubst %.dtbo,%.dt.yaml, $(dtb-))
 endif
 
 # Add subdir path

@@ -324,7 +326,7 @@ cmd_dtc = $(HOSTCC) -E $(dtc_cpp_flags) -x assembler-with-cpp -o $(dtc-tmp) $< ;
 		-d $(depfile).dtc.tmp $(dtc-tmp) ; \
 	cat $(depfile).pre.tmp $(depfile).dtc.tmp > $(depfile)
 
-$(obj)/%.dtb: $(src)/%.dts $(DTC) FORCE
+$(obj)/%.dtb $(obj)/%.dtbo: $(src)/%.dts $(DTC) FORCE
 	$(call if_changed_dep,dtc)