kbuild: Ensure .dtbo targets are applied to a base .dtb

It is a requirement that DT overlays in the kernel are applied at build
time to a base DTB in order to validate they can be applied and to
validate them against the DT schemas. DT overlays on their own may be
incomplete and can't be validated.

Add a kbuild check so this doesn't have to be checked and fixed
periodically.

Signed-off-by: Rob Herring (Arm) <robh@kernel.org>

diff --git a/scripts/Makefile.dtbs b/scripts/Makefile.dtbs
index 2d321b813600e910c34c9bc446b808fb68f93bf2..e092b460d5a1baf861dda8fc53963ccf909dd1ac 100644 (file)
--- a/scripts/Makefile.dtbs
+++ b/scripts/Makefile.dtbs
@@ -1,5 +1,7 @@
 # SPDX-License-Identifier: GPL-2.0-only
 
+all-dtb := $(dtb-y) $(dtb-)
+
 # If CONFIG_OF_ALL_DTBS is enabled, all DT blobs are built
 dtb-$(CONFIG_OF_ALL_DTBS) += $(dtb-)
 
@@ -10,6 +12,13 @@ real-dtb-y := $(call real-search, $(dtb-y), .dtb, -dtbs)
 # Base DTB that overlay is applied onto
 base-dtb-y := $(filter %.dtb, $(call real-search, $(multi-dtb-y), .dtb, -dtbs))
 
+# Ensure that any .dtbo is applied to at least one base .dtb. Otherwise, it
+# does not get validated.
+applied-dtbo := $(filter %.dtbo, \
+       $(call real-search, $(call multi-search, $(all-dtb), .dtb, -dtbs), .dtb, -dtbs))
+unapplied-dtbo := $(filter-out $(applied-dtbo),$(filter %.dtbo, $(dtb-y)))
+$(if $(unapplied-dtbo), $(warning .dtbo is not applied to any base: $(unapplied-dtbo)))
+
 dtb-y           := $(addprefix $(obj)/, $(dtb-y))
 multi-dtb-y     := $(addprefix $(obj)/, $(multi-dtb-y))
 real-dtb-y      := $(addprefix $(obj)/, $(real-dtb-y))