1 files changed, 58 insertions, 0 deletions
diff --git a/scripts/Makefile.asm-generic b/scripts/Makefile.asm-generic
new file mode 100644
index 000000000..8d01b37b7
--- /dev/null
+++ b/scripts/Makefile.asm-generic
@@ -0,0 +1,58 @@
+# SPDX-License-Identifier: GPL-2.0
+# include/asm-generic contains a lot of files that are used
+# verbatim by several architectures.
+#
+# This Makefile reads the file arch/$(SRCARCH)/include/(uapi/)/asm/Kbuild
+# and for each file listed in this file with generic-y creates
+# a small wrapper file in arch/$(SRCARCH)/include/generated/(uapi/)/asm.
+
+PHONY := all
+all:
+
+src := $(subst /generated,,$(obj))
+
+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
+
+redundant := $(filter $(mandatory-y) $(generated-y), $(generic-y))
+redundant += $(foreach f, $(generic-y), $(if $(wildcard $(srctree)/$(src)/$(f)),$(f)))
+redundant := $(sort $(redundant))
+$(if $(redundant),\
+	$(warning redundant generic-y found in $(src)/Kbuild: $(redundant)))
+
+# If arch does not implement mandatory headers, fallback to asm-generic ones.
+mandatory-y := $(filter-out $(generated-y), $(mandatory-y))
+generic-y   += $(foreach f, $(mandatory-y), $(if $(wildcard $(srctree)/$(src)/$(f)),,$(f)))
+
+generic-y   := $(addprefix $(obj)/, $(generic-y))
+generated-y := $(addprefix $(obj)/, $(generated-y))
+
+# Remove stale wrappers when the corresponding files are removed from generic-y
+old-headers := $(wildcard $(obj)/*.h)
+unwanted    := $(filter-out $(generic-y) $(generated-y),$(old-headers))
+
+quiet_cmd_wrap = WRAP    $@
+      cmd_wrap = echo "\#include <asm-generic/$*.h>" > $@
+
+quiet_cmd_remove = REMOVE  $(unwanted)
+      cmd_remove = rm -f $(unwanted)
+
+all: $(generic-y)
+	$(if $(unwanted),$(call cmd,remove))
+	@:
+
+$(obj)/%.h:
+	$(call cmd,wrap)
+
+# Create output directory. Skip it if at least one old header exists
+# since we know the output directory already exists.
+ifeq ($(old-headers),)
+$(shell mkdir -p $(obj))
+endif
+
+.PHONY: $(PHONY)