[PATCH V9 2/4] kbuild: Add generic rule to apply fdtoverlay

[Viresh Kumar]

From: Rob Herring <robh@xxxxxxxxxx>

Add a generic rule to apply fdtoverlay in Makefile.lib, so every
platform doesn't need to carry the complex rule.

The platform's Makefile only needs to have this now:

 DTC_FLAGS_foo_base += -@
 foo-dtbs := foo_base.dtb foo_overlay1.dtbo foo_overlay2.dtbo
 dtb-y := foo.dtb

We don't want to run schema checks on foo.dtb (as foo.dts doesn't exist)
and the Makefile is updated accordingly.

Signed-off-by: Rob Herring <robh@xxxxxxxxxx>
Co-developed-by: Viresh Kumar <viresh.kumar@xxxxxxxxxx>
Signed-off-by: Viresh Kumar <viresh.kumar@xxxxxxxxxx>
---
 scripts/Makefile.lib | 24 ++++++++++++++++++++++--
 1 file changed, 22 insertions(+), 2 deletions(-)

diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
index a2658242d956..c430fbb36763 100644
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib
@@ -58,6 +58,10 @@ real-search = $(foreach m,$(1), $(if $(strip $(call suffix-search,$(m),$(2) -)),
 real-obj-y := $(call real-search, $(obj-y),-objs -y)
 real-obj-m := $(call real-search, $(obj-m),-objs -y -m)
 
+# List all dtbs to be generated by fdtoverlay
+overlay-y := $(foreach m,$(dtb-y), $(if $(strip $($(m:.dtb=-dtbs))),$(m),))
+overlay-$(CONFIG_OF_ALL_DTBS) += $(foreach m,$(dtb-), $(if $(strip $($(m:.dtb=-dtbs))),$(m),))
+
 always-y += $(always-m)
 
 # hostprogs-always-y += foo
@@ -72,14 +76,21 @@ userprogs += $(userprogs-always-y) $(userprogs-always-m)
 always-y += $(userprogs-always-y) $(userprogs-always-m)
 
 # DTB
+# Add base dtb and overlay dtbo
+dtb-y += $(foreach m,$(overlay-y), $($(m:.dtb=-dtbs)))
+
 # If CONFIG_OF_ALL_DTBS is enabled, all DT blobs are built
 dtb-$(CONFIG_OF_ALL_DTBS)       += $(dtb-)
 
 always-y			+= $(dtb-y)
 
 ifneq ($(CHECK_DTBS),)
-always-y += $(patsubst %.dtb,%.dt.yaml, $(dtb-y))
-always-y += $(patsubst %.dtbo,%.dt.yaml, $(dtb-y))
+# Don't run schema checks for dtbs created by fdtoverlay as they don't
+# have corresponding dts files.
+dt-yaml-y := $(filter-out $(overlay-y),$(dtb-y))
+
+always-y += $(patsubst %.dtb,%.dt.yaml, $(dt-yaml-y))
+always-y += $(patsubst %.dtbo,%.dt.yaml, $(dt-yaml-y))
 endif
 
 # Add subdir path
@@ -337,6 +348,15 @@ $(obj)/%.dtb: $(src)/%.dts $(DTC) FORCE
 $(obj)/%.dtbo: $(src)/%.dts $(DTC) FORCE
 	$(call if_changed_dep,dtc)
 
+overlay-y := $(addprefix $(obj)/, $(overlay-y))
+
+quiet_cmd_fdtoverlay = DTOVL   $@
+      cmd_fdtoverlay = $(objtree)/scripts/dtc/fdtoverlay -o $@ -i $(real-prereqs)
+
+$(overlay-y): FORCE
+	$(call if_changed,fdtoverlay)
+$(call multi_depend, $(overlay-y), .dtb, -dtbs)
+
 DT_CHECKER ?= dt-validate
 DT_BINDING_DIR := Documentation/devicetree/bindings
 # DT_TMP_SCHEMA may be overridden from Documentation/devicetree/bindings/Makefile
-- 
2.25.0.rc1.19.g042ed3e048af