image: improve uImage.FIT device tree overlay support

Instead of generating full config nodes incl. kernel, generate minimal
config nodes for device tree overlays to be applied to the main config.
In this way, multiple device tree overlays can be applied more easily.
While at it change filenames to upstream style, ie. use dtso and dtbo
suffix for device tree overlays.

Signed-off-by: Daniel Golle <[email protected]>

include/image-commands.mk

@@ -307,7 +307,7 @@ define Build/fit
 		$(if $(DEVICE_FDT_NUM),-n $(DEVICE_FDT_NUM)) \
 		$(if $(DEVICE_DTS_DELIMITER),-l $(DEVICE_DTS_DELIMITER)) \
 		$(if $(DEVICE_DTS_LOADADDR),-s $(DEVICE_DTS_LOADADDR)) \
-		$(if $(DEVICE_DTS_OVERLAY),$(foreach dtso,$(DEVICE_DTS_OVERLAY), -O $(dtso):$(KERNEL_BUILD_DIR)/image-$(dtso).dtb)) \
+		$(if $(DEVICE_DTS_OVERLAY),$(foreach dtso,$(DEVICE_DTS_OVERLAY), -O $(dtso):$(KERNEL_BUILD_DIR)/image-$(dtso).dtbo)) \
 		-c $(if $(DEVICE_DTS_CONFIG),$(DEVICE_DTS_CONFIG),"config-1") \
 		-A $(LINUX_KARCH) -v $(LINUX_VERSION)
 	PATH=$(LINUX_DIR)/scripts/dtc:$(PATH) mkimage $(if $(findstring external,$(word 3,$(1))),\

include/image.mk

@@ -554,16 +554,33 @@ define Device/Build/dtb
   image_prepare: $(KDIR)/image-$(1).dtb
   endif
 
+endef
+
+define Device/Build/dtbo
+  ifndef BUILD_DTS_$(1)
+  BUILD_DTS_$(1) := 1
+  $(KDIR)/image-$(1).dtbo: FORCE
+	$(call Image/BuildDTB,$(strip $(2))/$(strip $(3)).dtso,$$@)
+
+  image_prepare: $(KDIR)/image-$(1).dtbo
+  endif
+
 endef
 endif
 
 define Device/Build/kernel
-  $$(eval $$(foreach dts,$$(DEVICE_DTS) $$(DEVICE_DTS_OVERLAY), \
+  $$(eval $$(foreach dts,$$(DEVICE_DTS), \
 	$$(call Device/Build/dtb,$$(notdir $$(dts)), \
 		$$(if $$(DEVICE_DTS_DIR),$$(DEVICE_DTS_DIR),$$(DTS_DIR)), \
 		$$(dts) \
 	) \
   ))
+  $$(eval $$(foreach dtso,$$(DEVICE_DTS_OVERLAY), \
+	$$(call Device/Build/dtbo,$$(notdir $$(dtso)), \
+		$$(if $$(DEVICE_DTS_DIR),$$(DEVICE_DTS_DIR),$$(DTS_DIR)), \
+		$$(dtso) \
+	) \
+  ))
 
   $(KDIR)/$$(KERNEL_NAME):: image_prepare
   $$(_TARGET): $$(if $$(KERNEL_INSTALL),$(BIN_DIR)/$$(KERNEL_IMAGE))

scripts/mkits.sh

@@ -191,13 +191,10 @@ OVCONFIGS=""
 "
 	OVCONFIGS="$OVCONFIGS
 
-		config-$ovname {
-			description = \"OpenWrt ${DEVICE} with $ovname\";
-			kernel = \"kernel${REFERENCE_CHAR}1\";
-			fdt = \"fdt${REFERENCE_CHAR}$FDTNUM\", \"$ovnode\";
-			${LOADABLES:+loadables = ${LOADABLES};}
+		$ovname {
+			description = \"OpenWrt ${DEVICE} overlay $ovname\";
+			fdt = \"$ovnode\";
 			${COMPATIBLE_PROP}
-			${INITRD_PROP}
 		};
 	"
 done