kernel: Support building dtbimage with mkdtboimg.py config

Change-Id: Ic0efbf0308e334c1cfe0df0493caa71afe27a621

build/tasks/kernel.mk

@@ -44,6 +44,8 @@
 #                                          For example, for ARM devices,
 #                                          use zImage-dtb instead of zImage.
 #
+#   BOARD_DTB_CFG                      = Path to a mkdtboimg.py config file for dtb.img
+#
 #   BOARD_DTBO_CFG                     = Path to a mkdtboimg.py config file
 #
 #   BOARD_CUSTOM_DTBOIMG_MK            = Path to a custom dtboimage makefile
@@ -501,6 +503,10 @@ ifeq ($(BOARD_PREBUILT_DTBIMAGE_DIR),)
 $(DTB_OUT):
 	mkdir -p $(DTB_OUT)
 
+ifdef BOARD_DTB_CFG
+MKDTBOIMG := $(HOST_OUT_EXECUTABLES)/mkdtboimg.py$(HOST_EXECUTABLE_SUFFIX)
+$(INSTALLED_DTBIMAGE_TARGET): $(MKDTBOIMG)
+endif
 $(INSTALLED_DTBIMAGE_TARGET): $(DTC) $(DTB_OUT)
 ifeq ($(TARGET_WANTS_EMPTY_DTB),true)
 	@rm -f $@
@@ -510,7 +516,11 @@ else
 	$(hide) find $(DTB_OUT)/arch/$(KERNEL_ARCH)/boot/dts -type f -name "*.dtb" | xargs rm -f
 	$(call make-dtb-target,$(KERNEL_DEFCONFIG))
 	$(call make-dtb-target,$(TARGET_KERNEL_DTB))
+ifdef BOARD_DTB_CFG
+	$(MKDTBOIMG) cfg_create $@ $(BOARD_DTB_CFG) -d $(DTB_OUT)/arch/$(KERNEL_ARCH)/boot/dts
+else
 	cat $(shell find $(DTB_OUT)/arch/$(KERNEL_ARCH)/boot/dts -type f -name "*.dtb" | sort) > $@
+endif # BOARD_DTB_CFG
 	$(hide) touch -c $(DTB_OUT)
 endif # !TARGET_WANTS_EMPTY_DTB