[PATCH] kbuild: add dtbs target for building all dtbs of an ARCH

[Ahmad Fatoum]

As described in the documentation, upstream device trees extended by
barebox should take care to cause compile errors, not runtime errors,
when the paths they extend disappear. This way, breakage can be easily
detected when synchronizing the dts/ directory and fixed right then.

Make this process easier by providing a dtbs target that builds all
device trees in arch/$(SRCARCH)/dts/ if available.

Signed-off-by: Ahmad Fatoum <a.fatoum at pengutronix.de>
---
 Makefile | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/Makefile b/Makefile
index 0da032532712..9fa741966c00 100644
--- a/Makefile
+++ b/Makefile
@@ -990,6 +990,20 @@ include/generated/version.h: FORCE
 include/generated/utsrelease.h: include/config/kernel.release FORCE
 	$(call filechk,utsrelease.h)
 
+# ---------------------------------------------------------------------------
+# Devicetree files
+
+ifneq ($(wildcard $(srctree)/arch/$(SRCARCH)/dts/),)
+dtstree := arch/$(SRCARCH)/dts
+endif
+
+ifneq ($(dtstree),)
+
+PHONY += dtbs
+dtbs: $(patsubst $(srctree)/%.dts,$(objtree)/%.dtb,$(wildcard $(srctree)/$(dtstree)/*.dts))
+
+endif
+
 # ---------------------------------------------------------------------------
 # Modules
 
@@ -1165,6 +1179,10 @@ help:
 	@$(if $(archhelp),$(archhelp),\
 		echo '  No architecture specific help defined for $(SRCARCH)')
 	@echo  ''
+	@$(if $(dtstree), \
+		echo '  Devicetree:'; \
+		echo '    * dtbs             - Build device tree blobs for all boards'; \
+		echo '')
 	@$(if $(boards), \
 		$(foreach b, $(boards), \
 		printf "  %-24s - Build for %s\\n" $(b) $(subst _defconfig,,$(b));) \
-- 
2.27.0