kbuild: refactor Makefile.asm-generic

 - Use conventional $(MAKE) $(asm-generic)=<dir> style
   for directory descending

 - Remove unneeded FORCE since "all" is a phony target

 - Remove unneeded "_dummy :=" assignment

 - Skip $(shell mkdir ...) when headers exist in the directory

 - Misc cleanups

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Sam Ravnborg <sam@ravnborg.org>

1 files changed, 4 insertions, 4 deletions

diff --git a/Makefile b/Makefile
index 00630cf04d84..6f3df2d786dd 100644
--- a/Makefile
+++ b/Makefile
@@ -1119,13 +1119,13 @@ prepare0: archprepare
 prepare: prepare0 prepare-objtool
 
 # Support for using generic headers in asm-generic
+asm-generic := -f $(srctree)/scripts/Makefile.asm-generic obj
+
 PHONY += asm-generic uapi-asm-generic
 asm-generic: uapi-asm-generic
-        $(Q)$(MAKE) -f $(srctree)/scripts/Makefile.asm-generic \
-                    src=asm obj=arch/$(SRCARCH)/include/generated/asm
+        $(Q)$(MAKE) $(asm-generic)=arch/$(SRCARCH)/include/generated/asm
 uapi-asm-generic:
-        $(Q)$(MAKE) -f $(srctree)/scripts/Makefile.asm-generic \
-                    src=uapi/asm obj=arch/$(SRCARCH)/include/generated/uapi/asm
+        $(Q)$(MAKE) $(asm-generic)=arch/$(SRCARCH)/include/generated/uapi/asm
 
 PHONY += prepare-objtool
 prepare-objtool: $(objtool_target)