[PATCH] Makefile: Fix include directory for OF_UPSTREAM

[Patrick Barsanti]

Always prioritizing u-boot includes causes problems when trying to
migrate boards to OF_UPSTREAM that have divergent devicetree files with
respect to the upstream ones.

For example, migrating a board based on `imx6ul.dtsi` to OF_UPSTREAM
breaks it, as there are some missing defines in the local dtsi file;
the solutions would be to either patch it, which defeats the purpose of
OF_UPSTREAM, or delete it entirely. This last option would then break all
the other boards which have not yet been migrated to OF_UPSTREAM.

The opposite problem also exists: by always prioritizing upstream
includes, if changes are made in the kernel headers and devicetree
files that are not backwards compatible, again all boards which have not
been migrated to OF_UPSTREAM will break.

This patch fixes this problem by prioritizing upstream includes when
`CONFIG_OF_UPSTREAM=y`, while keeping current prioritization when
it is not.

Signed-off-by: Patrick Barsanti <patrick.barsanti at amarulasolutions.com>
---
 Makefile | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/Makefile b/Makefile
index 79b28c2d81..899ae664ca 100644
--- a/Makefile
+++ b/Makefile
@@ -826,6 +826,19 @@ KBUILD_HOSTCFLAGS += $(if $(CONFIG_TOOLS_DEBUG),-g)
 
 # Use UBOOTINCLUDE when you must reference the include/ directory.
 # Needed to be compatible with the O= option
+ifeq ($(CONFIG_OF_UPSTREAM),y)
+UBOOTINCLUDE    := \
+	-I$(srctree)/dts/upstream/include \
+	-Iinclude \
+	$(if $(KBUILD_SRC), -I$(srctree)/include) \
+	$(if $(CONFIG_$(SPL_)SYS_THUMB_BUILD), \
+		$(if $(CONFIG_HAS_THUMB2), \
+			$(if $(CONFIG_CPU_V7M), \
+				-I$(srctree)/arch/arm/thumb1/include), \
+			-I$(srctree)/arch/arm/thumb1/include)) \
+	-I$(srctree)/arch/$(ARCH)/include \
+	-include $(srctree)/include/linux/kconfig.h
+else
 UBOOTINCLUDE    := \
 	-Iinclude \
 	$(if $(KBUILD_SRC), -I$(srctree)/include) \
@@ -837,6 +850,7 @@ UBOOTINCLUDE    := \
 	-I$(srctree)/arch/$(ARCH)/include \
 	-include $(srctree)/include/linux/kconfig.h \
 	-I$(srctree)/dts/upstream/include
+endif
 
 NOSTDINC_FLAGS += -nostdinc -isystem $(shell $(CC) -print-file-name=include)
 
-- 
2.43.0