kbuild: Allow to specify composite modules with modname-m

This allows to write

drm-$(CONFIG_AGP) += drm_agpsupport.o

without having to handle CONFIG_AGP=y vs. CONFIG_AGP=m. Only support
this syntax for modules, since built-in code depending on something
modular cannot work and init/Makefile actually relies on the current
semantics. There are a few drivers which adapted to the current
semantics out of necessity; these are fixed to also work when the
respective subsystem is modular.

Acked-by: Peter Chen <[e-mail]> [chipidea]
Signed-off-by: Michal Marek <[e-mail]>

drivers/misc/ibmasm/ibmasm.h

···
 void ibmasmfs_add_sp(struct service_processor *sp);
 
 /* uart */
-#ifdef CONFIG_SERIAL_8250
+#if IS_ENABLED(CONFIG_SERIAL_8250)
 void ibmasm_register_uart(struct service_processor *sp);
 void ibmasm_unregister_uart(struct service_processor *sp);
 #else

drivers/usb/chipidea/otg_fsm.h

···
 /* SSEND time before SRP */
 #define TB_SSEND_SRP         (1500)	/* minimum 1.5 sec, section:5.1.2 */
 
-#ifdef CONFIG_USB_OTG_FSM
+#if IS_ENABLED(CONFIG_USB_OTG_FSM)
 
 int ci_hdrc_otg_fsm_init(struct ci_hdrc *ci);
 int ci_otg_fsm_work(struct ci_hdrc *ci);

fs/logfs/logfs.h

···
 #endif
 
 /* dev_mtd.c */
-#ifdef CONFIG_MTD
+#if IS_ENABLED(CONFIG_MTD)
 int logfs_get_sb_mtd(struct logfs_super *s, int mtdnr);
 #else
 static inline int logfs_get_sb_mtd(struct logfs_super *s, int mtdnr)

scripts/Makefile.build

···
 #    <composite-object>-objs := <list of .o files>
 #  or
 #    <composite-object>-y    := <list of .o files>
+#  or
+#    <composite-object>-m    := <list of .o files>
+#  The -m syntax only works if <composite object> is a module
 link_multi_deps =                     \
 $(filter $(addprefix $(obj)/,         \
 $($(subst $(obj)/,,$(@:.o=-objs)))    \
-$($(subst $(obj)/,,$(@:.o=-y)))), $^)
+$($(subst $(obj)/,,$(@:.o=-y)))       \
+$($(subst $(obj)/,,$(@:.o=-m)))), $^)
 
 quiet_cmd_link_multi-y = LD      $@
 cmd_link_multi-y = $(LD) $(ld_flags) -r -o $@ $(link_multi_deps) $(cmd_secanalysis)
···
 $(multi-used-m): FORCE
 	$(call if_changed,link_multi-m)
 	@{ echo $(@:.o=.ko); echo $(link_multi_deps); } > $(MODVERDIR)/$(@F:.o=.mod)
-$(call multi_depend, $(multi-used-m), .o, -objs -y)
+$(call multi_depend, $(multi-used-m), .o, -objs -y -m)
 
 targets += $(multi-used-y) $(multi-used-m)
 

scripts/Makefile.lib

···
 
 # if $(foo-objs) exists, foo.o is a composite object
 multi-used-y := $(sort $(foreach m,$(obj-y), $(if $(strip $($(m:.o=-objs)) $($(m:.o=-y))), $(m))))
-multi-used-m := $(sort $(foreach m,$(obj-m), $(if $(strip $($(m:.o=-objs)) $($(m:.o=-y))), $(m))))
+multi-used-m := $(sort $(foreach m,$(obj-m), $(if $(strip $($(m:.o=-objs)) $($(m:.o=-y)) $($(m:.o=-m))), $(m))))
 multi-used   := $(multi-used-y) $(multi-used-m)
 single-used-m := $(sort $(filter-out $(multi-used-m),$(obj-m)))
 
···
 
 # Replace multi-part objects by their individual parts, look at local dir only
 real-objs-y := $(foreach m, $(filter-out $(subdir-obj-y), $(obj-y)), $(if $(strip $($(m:.o=-objs)) $($(m:.o=-y))),$($(m:.o=-objs)) $($(m:.o=-y)),$(m))) $(extra-y)
-real-objs-m := $(foreach m, $(obj-m), $(if $(strip $($(m:.o=-objs)) $($(m:.o=-y))),$($(m:.o=-objs)) $($(m:.o=-y)),$(m)))
+real-objs-m := $(foreach m, $(obj-m), $(if $(strip $($(m:.o=-objs)) $($(m:.o=-y)) $($(m:.o=-m))),$($(m:.o=-objs)) $($(m:.o=-y)) $($(m:.o=-m)),$(m)))
 
 # Add subdir path