From f86d9605a58c942133c395c1f978286ae1b7f11c Mon Sep 17 00:00:00 2001
From: Elliot Berman <eberman@codeaurora.org>
Date: Thu, 15 Oct 2020 10:50:19 -0700
Subject: [PATCH] Makefile: devicetree: Introduce support for out-of-tree dtbs

Introduce support to compile devicetree sources out-of-tree. This is
useful so that dt-bindings and tools are provided Kbuild.

Conflicts:
      Makefile
      scripts/Makefile.lib

Change-Id: I3c15e43dd132b01d5ea7a4518aa91e809e83eb48
Signed-off-by: Elliot Berman <eberman@codeaurora.org>
Signed-off-by: Guru Das Srinagesh <quic_gurus@quicinc.com>
---
 Makefile             | 55 ++++++++++++++++++++++++++++++++++++++++++++
 scripts/Makefile.lib |  2 +-
 2 files changed, 56 insertions(+), 1 deletion(-)

diff --git a/Makefile b/Makefile
index 755cf8fc4549..a435d24db30c 100644
--- a/Makefile
+++ b/Makefile
@@ -1146,6 +1146,61 @@ endif
 	$(Q)$(MAKE) $(hdr-inst)=$(hdr-prefix)include/uapi
 	$(Q)$(MAKE) $(hdr-inst)=$(hdr-prefix)arch/$(SRCARCH)/include/uapi
 
+# ---------------------------------------------------------------------------
+# Devicetree files
+ifeq ($(KBUILD_EXTMOD),)
+ifneq ($(wildcard $(srctree)/arch/$(SRCARCH)/boot/dts/),)
+dtstree := arch/$(SRCARCH)/boot/dts
+endif
+
+else # KBUILD_EXTMOD
+# Devicetree source should live in $(KBUILD_EXTMOD)/arch/$(SRCARCH)/boot/dts/
+# But it may live inside some other folder relative to KBUILD_EXTMOD, as specified
+# by KBUILD_EXTMOD_DTS
+KBUILD_EXTMOD_DTS = arch/$(SRCARCH)/boot/dts
+ifneq ($(wildcard $(KBUILD_EXTMOD)/$(KBUILD_EXTMOD_DTS)/ $(srctree)/$(KBUILD_EXTMOD)/$(KBUILD_EXTMOD_DTS)/),)
+dtstree := $(KBUILD_EXTMOD)/$(KBUILD_EXTMOD_DTS)
+endif
+endif
+
+ifneq ($(dtstree),)
+
+%.dtb: include/config/kernel.release scripts_dtc
+	$(Q)$(MAKE) $(build)=$(dtstree) $(dtstree)/$@
+
+PHONY += dtbs dtbs_install dtbs_check
+dtbs: include/config/kernel.release scripts_dtc
+	$(Q)$(MAKE) $(build)=$(dtstree)
+
+ifneq ($(filter dtbs_check, $(MAKECMDGOALS)),)
+export CHECK_DTBS=y
+dtbs: dt_binding_check
+endif
+
+dtbs_check: dtbs
+
+dtbs_install:
+	$(Q)$(MAKE) $(dtbinst)=$(dtstree) dst=$(INSTALL_DTBS_PATH)
+
+ifdef CONFIG_OF_EARLY_FLATTREE
+all: dtbs
+endif
+
+endif
+
+PHONY += scripts_dtc
+scripts_dtc: scripts_basic
+	$(Q)$(MAKE) $(build)=scripts/dtc
+
+ifneq ($(filter dt_binding_check, $(MAKECMDGOALS)),)
+export CHECK_DT_BINDING=y
+endif
+
+PHONY += dt_binding_check
+dt_binding_check: scripts_dtc
+	$(Q)$(MAKE) $(build)=Documentation/devicetree/bindings
+
+
 ifeq ($(KBUILD_EXTMOD),)
 core-y			+= kernel/ certs/ mm/ fs/ ipc/ security/ crypto/
 core-$(CONFIG_BLOCK)	+= block/
diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
index 243ae7b9acb7..67c8be4c1f58 100644
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib
@@ -226,7 +226,7 @@ ld_flags       = $(KBUILD_LDFLAGS) $(ldflags-y) $(LDFLAGS_$(@F))
 
 # ANDROID: Allow DTC_INCLUDE to be set by the BUILD_CONFIG. This allows one to
 # compile an out-of-tree device tree.
-DTC_INCLUDE    += $(srctree)/scripts/dtc/include-prefixes
+DTC_INCLUDE    += $(srctree)/scripts/dtc/include-prefixes $(KBUILD_DTC_INCLUDE)
 
 dtc_cpp_flags  = -Wp,-MMD,$(depfile).pre.tmp -nostdinc                    \
 		 $(addprefix -I,$(DTC_INCLUDE))                          \