kbuild: add kbuild-file macro

While building, installing, cleaning, Kbuild visits sub-directories
and includes 'Kbuild' or 'Makefile' that exists there.

Add 'kbuild-file' macro, and reuse it from scripts/Makefie.*
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>
Reviewed-by: Alexander Lobakin <alobakin@pm.me>
Tested-by: Alexander Lobakin <alobakin@pm.me>

scripts/Kbuild.include

@@ -40,6 +40,11 @@ escsq = $(subst $(squote),'\$(squote)',$1)
 # Quote a string to pass it to C files. foo => '"foo"'
 stringify = $(squote)$(quote)$1$(quote)$(squote)
 
+###
+# The path to Kbuild or Makefile. Kbuild has precedence over Makefile.
+kbuild-dir = $(if $(filter /%,$(src)),$(src),$(srctree)/$(src))
+kbuild-file = $(or $(wildcard $(kbuild-dir)/Kbuild),$(kbuild-dir)/Makefile)
+
 ###
 # Easy method for doing a status message
        kecho := :

scripts/Makefile.asm-generic

@@ -10,15 +10,15 @@ PHONY := all
 all:
 
 src := $(subst /generated,,$(obj))
--include $(src)/Kbuild
+
+include $(srctree)/scripts/Kbuild.include
+-include $(kbuild-file)
 
 # $(generic)/Kbuild lists mandatory-y. Exclude um since it is a special case.
 ifneq ($(SRCARCH),um)
 include $(srctree)/$(generic)/Kbuild
 endif
 
-include $(srctree)/scripts/Kbuild.include
-
 redundant := $(filter $(mandatory-y) $(generated-y), $(generic-y))
 redundant += $(foreach f, $(generic-y), $(if $(wildcard $(srctree)/$(src)/$(f)),$(f)))
 redundant := $(sort $(redundant))

scripts/Makefile.build

@@ -38,11 +38,7 @@ subdir-ccflags-y :=
 
 include $(srctree)/scripts/Kbuild.include
 include $(srctree)/scripts/Makefile.compiler
-
-# The filename Kbuild has precedence over Makefile
-kbuild-dir := $(if $(filter /%,$(src)),$(src),$(srctree)/$(src))
-include $(or $(wildcard $(kbuild-dir)/Kbuild),$(kbuild-dir)/Makefile)
-
+include $(kbuild-file)
 include $(srctree)/scripts/Makefile.lib
 
 # Do not include hostprogs rules unless needed.

scripts/Makefile.clean

@@ -9,10 +9,7 @@ PHONY := __clean
 __clean:
 
 include $(srctree)/scripts/Kbuild.include
-
-# The filename Kbuild has precedence over Makefile
-kbuild-dir := $(if $(filter /%,$(src)),$(src),$(srctree)/$(src))
-include $(or $(wildcard $(kbuild-dir)/Kbuild),$(kbuild-dir)/Makefile)
+include $(kbuild-file)
 
 # Figure out what we need to build from the various variables
 # ==========================================================================

scripts/Makefile.dtbinst

@@ -15,7 +15,7 @@ __dtbs_install:
 
 include include/config/auto.conf
 include $(srctree)/scripts/Kbuild.include
-include $(src)/Makefile
+include $(kbuild-file)
 
 dtbs    := $(addprefix $(dst)/, $(dtb-y) $(if $(CONFIG_OF_ALL_DTBS),$(dtb-)))
 subdirs := $(addprefix $(obj)/, $(subdir-y) $(subdir-m))

scripts/Makefile.modpost

@@ -93,7 +93,7 @@ obj := $(KBUILD_EXTMOD)
 src := $(obj)
 
 # Include the module's Makefile to find KBUILD_EXTRA_SYMBOLS
-include $(or $(wildcard $(src)/Kbuild), $(src)/Makefile)
+include $(kbuild-file)
 
 module.symvers-if-present := $(wildcard Module.symvers)
 output-symdump := $(KBUILD_EXTMOD)/Module.symvers