dts/Makefile: pass -undef -D__DTS__ to cpp
This brings U-Boot's cpp invocation into line with the way the Linux
kernel invokes cpp on device trees. Consistency will be useful to ensure
*.dts is portable between the two.
-undef also has the added advantage of not defining "linux", so DT
property names such as "linux,keymap" don't get mangled.
Signed-off-by: Stephen Warren <swarren@nvidia.com>
Acked-by: Simon Glass <sjg@chromium.org>
diff --git a/dts/Makefile b/dts/Makefile
index ccd552f..3cf991e 100644
--- a/dts/Makefile
+++ b/dts/Makefile
@@ -21,7 +21,7 @@
DTS_INCDIRS += $(SRCTREE)/board/$(VENDOR)/dts
DTS_INCDIRS += $(SRCTREE)/arch/$(ARCH)/dts
-DTS_CPPFLAGS := -x assembler-with-cpp \
+DTS_CPPFLAGS := -x assembler-with-cpp -undef -D__DTS__ \
-nostdinc $(addprefix -I,$(DTS_INCDIRS))
DTC_FLAGS := -R 4 -p 0x1000 \