kbuild: move asm-offsets.h rules to ./Kbuild

Generate include/generated/generic-asm-offsets.h and
include/generated/asm-offsets.h in ./Kbuild.

This commit also changes the include guard.

Before this commit, __ASM_OFFSETS_H__ was used for both of them.
So we could not include generic-asm-offsets.h and asm-offsets.h
at the same time.

This commit renames the include guard of the former to
__GENERIC_ASM_OFFSETS_H__.

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
diff --git a/Kbuild b/Kbuild
new file mode 100644
index 0000000..1d89761
--- /dev/null
+++ b/Kbuild
@@ -0,0 +1,87 @@
+#
+# Kbuild for top-level directory of U-Boot
+# This file takes care of the following:
+# 1) Generate generic-asm-offsets.h
+# 2) Generate asm-offsets.h
+
+#####
+# 1) Generate generic-asm-offsets.h
+
+generic-offsets-file := include/generated/generic-asm-offsets.h
+
+always  := $(generic-offsets-file)
+targets := $(generic-offsets-file) lib/asm-offsets.s
+
+quiet_cmd_generic-offsets = GEN     $@
+define cmd_generic-offsets
+	(set -e; \
+	 echo "#ifndef __GENERIC_ASM_OFFSETS_H__"; \
+	 echo "#define __GENERIC_ASM_OFFSETS_H__"; \
+	 echo "/*"; \
+	 echo " * DO NOT MODIFY."; \
+	 echo " *"; \
+	 echo " * This file was generated by Kbuild"; \
+	 echo " *"; \
+	 echo " */"; \
+	 echo ""; \
+	 sed -ne $(sed-y) $<; \
+	 echo ""; \
+	 echo "#endif" ) > $@
+endef
+
+# We use internal kbuild rules to avoid the "is up to date" message from make
+lib/asm-offsets.s: lib/asm-offsets.c FORCE
+	$(Q)mkdir -p $(dir $@)
+	$(call if_changed_dep,cc_s_c)
+
+$(obj)/$(generic-offsets-file): lib/asm-offsets.s Kbuild
+	$(Q)mkdir -p $(dir $@)
+	$(call cmd,generic-offsets)
+
+#####
+# 2) Generate asm-offsets.h
+#
+
+ifneq ($(wildcard $(srctree)/$(CPUDIR)/$(SOC)/asm-offsets.c),)
+offsets-file := include/generated/asm-offsets.h
+endif
+
+always  += $(offsets-file)
+targets += $(offsets-file)
+targets += $(CPUDIR)/$(SOC)/asm-offsets.s
+
+
+# Default sed regexp - multiline due to syntax constraints
+define sed-y
+	"/^->/{s:->#\(.*\):/* \1 */:; \
+	s:^->\([^ ]*\) [\$$#]*\([-0-9]*\) \(.*\):#define \1 \2 /* \3 */:; \
+	s:^->\([^ ]*\) [\$$#]*\([^ ]*\) \(.*\):#define \1 \2 /* \3 */:; \
+	s:->::; p;}"
+endef
+
+CFLAGS_asm-offsets.o := -DDO_DEPS_ONLY
+
+quiet_cmd_offsets = GEN     $@
+define cmd_offsets
+	(set -e; \
+	 echo "#ifndef __ASM_OFFSETS_H__"; \
+	 echo "#define __ASM_OFFSETS_H__"; \
+	 echo "/*"; \
+	 echo " * DO NOT MODIFY."; \
+	 echo " *"; \
+	 echo " * This file was generated by Kbuild"; \
+	 echo " *"; \
+	 echo " */"; \
+	 echo ""; \
+	 sed -ne $(sed-y) $<; \
+	 echo ""; \
+	 echo "#endif" ) > $@
+endef
+
+# We use internal kbuild rules to avoid the "is up to date" message from make
+$(CPUDIR)/$(SOC)/asm-offsets.s: $(CPUDIR)/$(SOC)/asm-offsets.c FORCE
+	$(Q)mkdir -p $(dir $@)
+	$(call if_changed_dep,cc_s_c)
+
+$(obj)/$(offsets-file): $(CPUDIR)/$(SOC)/asm-offsets.s
+	$(call cmd,offsets)