dts: Add alternative location for upstream DTB builds

Allow platform owners to mirror devicetree files from devitree-rebasing
directory into dts/upstream/src/$(ARCH) (special case for arm64). Then
build then along with any *-u-boot.dtsi file present in arch/$(ARCH)/dts
directory. Also add a new Makefile for arm64.

This will help easy migration for platforms which currently are compliant
with upstream Linux kernel devicetree files.

Signed-off-by: Sumit Garg <sumit.garg@linaro.org>

diff --git a/dts/Kconfig b/dts/Kconfig
index def0e172412f50354da9be8cc47b0492bb496e08..b9b6367154ef1f974b6fea4727335cf786e90d68 100644 (file)
--- a/dts/Kconfig
+++ b/dts/Kconfig
@@ -85,6 +85,22 @@ config OF_LIVE
          enables a live tree which is available after relocation,
          and can be adjusted as needed.
 
+config OF_UPSTREAM
+       bool "Enable use of devicetree imported from Linux kernel release"
+       help
+         Traditionally, U-Boot platforms used to have their custom devicetree
+         files or copy devicetree files from Linux kernel which are hard to
+         maintain and can usually get out-of-sync from Linux kernel. This
+         option enables platforms to migrate to devicetree-rebasing repo where
+         a regular sync will be maintained every major Linux kernel release
+         cycle. However, platforms can still have some custom u-boot specific
+         bits maintained as part of *-u-boot.dtsi files.
+
+         Note: This option should be set in Kconfig, for the SoC as a whole.
+         However, newer boards whose devicetree source files haven't landed in
+         the dts/upstream subtree, they can override this option to have the
+         DT build from existing U-Boot tree location instead.
+
 choice
        prompt "Provider of DTB for DT control"
        depends on OF_CONTROL

diff --git a/dts/Makefile b/dts/Makefile
index 3437e54033dbde816d8082de61b6d6d0e8f5e83d..d6c2c9daf31d64b6f26ef63af04a5e851f1042ab 100644 (file)
--- a/dts/Makefile
+++ b/dts/Makefile
@@ -10,10 +10,20 @@ ifeq ($(DEVICE_TREE),)
 DEVICE_TREE := unset
 endif
 
+ifeq ($(CONFIG_OF_UPSTREAM),y)
+ifeq ($(CONFIG_ARM64),y)
+dt_dir := dts/upstream/src/arm64
+else
+dt_dir := dts/upstream/src/$(ARCH)
+endif
+else
+dt_dir := arch/$(ARCH)/dts
+endif
+
 ifneq ($(EXT_DTB),)
 DTB := $(EXT_DTB)
 else
-DTB := arch/$(ARCH)/dts/$(DEVICE_TREE).dtb
+DTB := $(dt_dir)/$(DEVICE_TREE).dtb
 endif
 
 $(obj)/dt-$(SPL_NAME).dtb: dts/dt.dtb $(objtree)/tools/fdtgrep FORCE
@@ -41,7 +51,7 @@ $(DTB): arch-dtbs
 
 PHONY += arch-dtbs
 arch-dtbs:
-       $(Q)$(MAKE) $(build)=arch/$(ARCH)/dts dtbs
+       $(Q)$(MAKE) $(build)=$(dt_dir) dtbs
 
 ifeq ($(CONFIG_SPL_BUILD),y)
 obj-$(CONFIG_OF_EMBED) := dt-spl.dtb.o
@@ -65,4 +75,5 @@ clean-files := dt.dtb.S
 # Let clean descend into dts directories
 subdir- += ../arch/arc/dts ../arch/arm/dts ../arch/m68k/dts ../arch/microblaze/dts     \
           ../arch/mips/dts ../arch/nios2/dts ../arch/powerpc/dts ../arch/riscv/dts     \
-          ../arch/sandbox/dts ../arch/sh/dts ../arch/x86/dts ../arch/xtensa/dts
+          ../arch/sandbox/dts ../arch/sh/dts ../arch/x86/dts ../arch/xtensa/dts        \
+          ./upstream/src/arm64 ./upstream/src/$(ARCH)

diff --git a/dts/upstream/src/arm64/Makefile b/dts/upstream/src/arm64/Makefile
new file mode 100644 (file)
index 0000000..9a8f6aa
--- /dev/null
+++ b/dts/upstream/src/arm64/Makefile
@@ -0,0 +1,14 @@
+# SPDX-License-Identifier: GPL-2.0+
+
+include $(srctree)/scripts/Makefile.dts
+
+targets += $(dtb-y)
+
+# Add any required device tree compiler flags here
+DTC_FLAGS += -a 0x8
+
+PHONY += dtbs
+dtbs: $(addprefix $(obj)/, $(dtb-y))
+       @:
+
+clean-files := */*.dtb */*.dtbo