obj-y    :=
obj-m    :=
always   :=
targets  :=
.DEFAULT_GOAL := all

src := $(patsubst %/,%,$(obj))

-include $(srctree)/.config
-include $(obj)Kbuild

ifdef lib-y
  export cflags-y
else ifdef lib-m
  export cflags-y
endif

ifdef bin-y
  export cflags-y
  export ldflags-y
endif

ifneq ($(strip $(lib-y) $(lib-m) $(lib-n)),)
lib = $(lib-y)$(lib-m)$(lib-n)
endif
ifneq ($(strip $(bin-y) $(bin-n)),)
bin = $(bin-y)$(bin-n)
endif

objects := $(filter %.o,$(obj-y))
subdirs := $(filter %/,$(obj-y)) $(filter %/,$(obj-m))

cflags := $(cflags-y) $(KBUILD_CFLAGS) -MMD -MP
asflags := $(asflags-y) $(KBUILD_ASFLAGS)
ldflags := $(ldflags-y) $(KBUILD_LDFLAGS)

collect-obj-y = $(foreach e,$(shell echo 'all:; @echo $$(obj-y)' | \
  $(MAKE) -f $(obj)$(1)Kbuild -f - --no-print-directory 2>/dev/null),\
  $(if $(filter %/,$(e)),$(addprefix $(e),$(call collect-obj-y,$(1)$(e))),$(e)))

ifneq ($(strip $(lib-y) $(lib-m)),)
  subdir-objects := $(foreach d,$(subdirs),$(addprefix $(d),$(call collect-obj-y,$(d))))
  all-objects := $(objects) $(subdir-objects)
else ifdef bin-y
  subdir-objects := $(foreach d,$(subdirs),$(addprefix $(d),$(call collect-obj-y,$(d))))
  all-objects := $(objects) $(subdir-objects)
else
  all-objects := $(objects)
endif

deps := $(all-objects:.o=.d)
-include $(deps)

c-sources := $(wildcard $(addprefix $(obj),$(objects:.o=.c)))
s-sources := $(wildcard $(addprefix $(obj),$(objects:.o=.s)))
subdir-c-sources := $(wildcard $(addprefix $(obj),$(subdir-objects:.o=.c)))
subdir-s-sources := $(wildcard $(addprefix $(obj),$(subdir-objects:.o=.s)))

PHONY := all install

ifdef lib-y
all: $(obj)$(lib-y) $(addprefix $(obj),$(always))
$(obj)$(lib): $(addprefix $(obj),$(all-objects))
	$(MSG) AR "$@"
	$(Q)$(AR) rcs $@ $^

$(O)/$(parent)/$(lib-y): $(obj)$(lib-y)
	$(Q)mkdir -p $(O)/$(dir $@)
	$(Q)install -m 0644 $< $@

install: $(O)/$(parent)/$(lib-y)

else ifdef lib-m
all: $(obj)$(lib-m) $(addprefix $(obj),$(always))

$(obj)$(lib): $(addprefix $(obj),$(all-objects))
	$(MSG) AR "$@"
	$(Q)$(AR) rcs $@ $^

else ifdef bin-y
all: $(obj)$(bin-y) $(addprefix $(obj),$(always))

$(obj)$(bin-y): $(addprefix $(obj),$(all-objects)) $(libs-y) ${prereq}
	$(MSG) LD "$@"
	$(Q)$(LD) $(ldflags) -o $@ $^

$(O)/$(parent)/$(bin-y): $(obj)$(bin-y)
	$(Q)mkdir -p $(O)/$(parent)
	$(Q)install -m 0755 $< $@

install: $(O)/$(parent)/$(bin-y)
else
all: $(addprefix $(obj),$(all-objects)) $(subdirs) $(addprefix $(obj),$(always))

install: $(subdirs)
endif

PHONY += clean clean-%
clean: $(addprefix clean-,$(subdirs))
ifdef deps
	$(Q)rm -f $(addprefix $(obj),$(deps))
endif
ifdef targets
	$(Q)rm -f $(addprefix $(obj),$(targets))
endif
ifdef all-objects
	$(Q)rm -f $(addprefix $(obj),$(all-objects))
endif
ifdef lib
	$(Q)rm -f "$(obj)$(lib)"
endif
ifdef bin
	$(Q)rm -f $(obj)$(bin)
endif
ifdef always
	$(Q)rm -f $(addprefix $(obj),$(always))
endif

$(filter $(addprefix $(obj),$(all-objects)),$(c-sources:.c=.o) $(subdir-c-sources:.c=.o)): $(obj)%.o: $(obj)%.c
	$(MSG) CC "$@"
	$(Q)$(CC) $(cflags) -c $< -o $@

$(filter $(addprefix $(obj),$(all-objects)),$(s-sources:.s=.o) $(subdir-s-sources:.s=.o)): $(obj)%.o: $(obj)%.s
	$(MSG) AS "$@"
	$(Q)$(CC) $(asflags) -c $< -o $@

.PHONY: $(subdirs)
$(subdirs):
	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.build obj="$(obj)$@" parent="$(obj)" ${MAKECMDGOALS}

clean-%:
	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.build obj="$(obj)$*" clean

.PHONY: $(PHONY)