#Android makefile to build kernel as a part of Android Build

ifeq ($(KERNEL_DEFCONFIG),)
$(error KERNEL_DEFCONFIG must be set as environment variable)
endif

ifeq ($(INSTALLED_KERNEL_TARGET),)
KERNEL_OBJECTS := $(TARGET_OUT_INTERMEDIATES)/KERNEL_OBJ
INSTALLED_KERNEL_TARGET := $(PRODUCT_OUT)/kernel
INSTALLED_DTBOIMAGE_TARGET := $(PRODUCT_OUT)/dtbo.img
BOARD_PREBUILT_DTBOIMAGE := $(PRODUCT_OUT)/prebuilt_dtbo.img
INSTALLED_DTB_TARGET := $(PRODUCT_OUT)/dtb.img
BOARD_MKBOOTIMG_ARGS += \
	--second $(INSTALLED_DTB_TARGET) \
	--second_offset 0
endif

TARGET_KERNEL_ARCH := $(strip $(TARGET_KERNEL_ARCH))
ifeq ($(TARGET_KERNEL_ARCH),)
KERNEL_ARCH := arm64
else
KERNEL_ARCH := $(TARGET_KERNEL_ARCH)
endif

TARGET_KERNEL_MAKE_ENV := $(strip $(TARGET_KERNEL_MAKE_ENV))
ifeq ($(TARGET_KERNEL_MAKE_ENV),)
KERNEL_MAKE_ENV :=
else
KERNEL_MAKE_ENV := $(TARGET_KERNEL_MAKE_ENV)
endif

ifeq ($(CROSS_COMPILE),)
KERNEL_CROSS_COMPILE := aarch64-linux-android-
else
KERNEL_CROSS_COMPILE := $(CROSS_COMPILE)
endif

SOONG_GLOBAL_CONFIG := build/soong/cc/config/global.go
CLANG_VERSION := clang-4691093
CLANG_PATH := prebuilts/clang/host/linux-x86
CC :=$(PWD)/$(CLANG_PATH)/$(CLANG_VERSION)/bin/clang

KERNEL_LTO_ON = True
ifneq ($(KERNEL_LTO_ON),)
LLVM_AR :=$(PWD)/$(CLANG_PATH)/$(CLANG_VERSION)/bin/llvm-ar
LLVM_DIS :=$(PWD)/$(CLANG_PATH)/$(CLANG_VERSION)/bin/llvm-dis
LTO_LLVM_LIB_BASE = $(PWD)/$(CLANG_PATH)/$(CLANG_VERSION)/lib64/
LLVM_OPTIONS := LLVM_AR=$(LLVM_AR) LLVM_DIS=$(LLVM_DIS) LTO_LLVM_LIB_BASE=$(LTO_LLVM_LIB_BASE)
else
LLVM_OPTIONS :=
endif

ifeq ($(CLANG_TRIPLE),)
CLANG_TRIPLE := aarch64-linux-gnu-
else
CLANG_TRIPLE := $(CLANG_TRIPLE)
endif

BUILD_ROOT_LOC := ../../
KERNEL_OUT := $(TARGET_OUT_INTERMEDIATES)/kernel/$(TARGET_SOC)
KERNEL_OUT := $(KERNEL_OBJECTS)
ifeq ($(TARGET_PREBUILT_KERNEL),)

KERNEL_CONFIG := $(KERNEL_OBJECTS)/.config
KERNEL_BOOT := $(KERNEL_OBJECTS)/arch/$(KERNEL_ARCH)/boot
KERNEL_BIN := $(KERNEL_BOOT)/Image
KERNEL_DTB_DIR := $(KERNEL_BOOT)/dts/exynos
KERNEL_DTB := $(KERNEL_DTB_DIR)/exynos9610.dtb
MKDTIMG := $(HOST_OUT_EXECUTABLES)/mkdtimg

TARGET_KERNEL_SOURCE := kernel/$(TARGET_SOC)
KERNEL_DTB_SOURCE_DIR := $(TARGET_KERNEL_SOURCE)/arch/$(KERNEL_ARCH)/boot/dts/exynos
KERNEL_DTBO_CFG := $(KERNEL_DTB_SOURCE_DIR)/exynos9610_dtboimg.cfg
KERNEL_MERGE_CONFIG := $(TARGET_KERNEL_SOURCE)/scripts/kconfig/merge_config.sh
KERNEL_CONFIG_BASE := $(TARGET_KERNEL_SOURCE)/arch/$(KERNEL_ARCH)/configs
KERNEL_DEFCONFIG_PATH := $(KERNEL_CONFIG_BASE)/$(KERNEL_DEFCONFIG)

ifeq ($(TARGET_PRODUCT),kane_factory)
ERD9609_DEFCONFIG := erd9610_defconfig
ERD9609_DEFCONFIG_PATH := $(KERNEL_CONFIG_BASE)/$(ERD9609_DEFCONFIG)
ROBUSTA2_FACTORY_DEFCONFIG := robusta2_factory_defconfig
ROBUSTA2_FACTORY_DEFCONFIG_PATH := $(KERNEL_CONFIG_BASE)/$(ROBUSTA2_FACTORY_DEFCONFIG)
ERD9609_ROBUSTA2_FACTORY_DEFCONFIG := erd9610_robusta2_factory_defconfig
ERD9609_ROBUSTA2_FACTORY_DEFCONFIG_PATH := $(KERNEL_CONFIG_BASE)/$(ERD9609_ROBUSTA2_FACTORY_DEFCONFIG)
endif

ifeq ($(KERNEL_DEFCONFIG),)
$(error Kernel configuration not defined, cannot build kernel)
else

ifeq ($(TARGET_BUILD_VARIANT),eng)
MAKE_CONFIG_CMD := $(MAKE) -C $(TARGET_KERNEL_SOURCE) O=$(PWD)/$(KERNEL_OBJECTS) ARCH=$(KERNEL_ARCH) CROSS_COMPILE=$(KERNEL_CROSS_COMPILE) $(KERNEL_DEFCONFIG)
else
ifeq ($(TARGET_BUILD_VARIANT),userdebug)
KERNEL_USER_CFG := $(KERNEL_CONFIG_BASE)/$(TARGET_SOC)_userdebug.cfg
else
KERNEL_USER_CFG := $(KERNEL_CONFIG_BASE)/$(TARGET_SOC)_user.cfg
endif
MAKE_CONFIG_CMD := ARCH=$(KERNEL_ARCH) $(KERNEL_MERGE_CONFIG) -m -O $(TARGET_KERNEL_SOURCE) $(KERNEL_DEFCONFIG_PATH) $(KERNEL_USER_CFG);
MAKE_CONFIG_CMD += $(MAKE) -C $(TARGET_KERNEL_SOURCE) O=$(PWD)/$(KERNEL_OBJECTS) ARCH=$(KERNEL_ARCH) KCONFIG_ALLCONFIG=.config alldefconfig;
MAKE_CONFIG_CMD += $(MAKE) -C $(TARGET_KERNEL_SOURCE) distclean
endif

ifeq ($(N_KERNEL_BUILD_THREAD),)
N_KERNEL_BUILD_THREAD := 8
endif

include $(TARGET_KERNEL_SOURCE)/defconfig.mk


TARGET_PREBUILT_KERNEL := $(KERNEL_BIN)

# Make the kernel config
#   $1 output dir
#   $2 kernel config filepath
#   $3 defconfig
#   $4 kernel source
#   $5 kernel make env
#   $6 kernel architecture
#   $7 cross compile sub-command
#   $8 make command
define do-kernel-config
    ( cp $(3) $(2) && $(8) -C $(4) O=$(1) $(5) ARCH=$(6) CROSS_COMPILE=$(7) defoldconfig ) || ( rm -f $(2) && false )
endef


$(KERNEL_OUT):
	mkdir -p $(KERNEL_OUT)

.PHONY: kernel
kernel: $(KERNEL_BIN)

.PHONY: kernel-distclean
kernel-distclean:
	$(MAKE) -C $(TARGET_KERNEL_SOURCE) ARCH=$(KERNEL_ARCH) CROSS_COMPILE=$(KERNEL_CROSS_COMPILE) distclean

$(KERNEL_CONFIG): $(TARGET_DEFCONFIG)
	$(hide) echo "make $(KERNEL_CONFIG)"
	$(call do-kernel-config,$(BUILD_ROOT_LOC)$(KERNEL_OUT),$@,$(TARGET_DEFCONFIG),$(TARGET_KERNEL_SOURCE),$(KERNEL_MAKE_ENV),$(KERNEL_ARCH),$(KERNEL_CROSS_COMPILE),$(MAKE))

$(KERNEL_BIN): $(KERNEL_OUT) $(KERNEL_CONFIG)
	$(hide) echo "Building kernel..."
	$(MAKE) -C $(TARGET_KERNEL_SOURCE) O=$(PWD)/$(KERNEL_OBJECTS) ARCH=$(KERNEL_ARCH) CROSS_COMPILE=$(KERNEL_CROSS_COMPILE) CLANG_TRIPLE=$(CLANG_TRIPLE) CC=$(CC) $(LLVM_OPTIONS) -j$(N_KERNEL_BUILD_THREAD)

$(INSTALLED_KERNEL_TARGET): $(INSTALLED_DTBOIMAGE_TARGET)
	cp $(KERNEL_BIN) $(INSTALLED_KERNEL_TARGET)
	cp $(KERNEL_DTB) $(INSTALLED_DTB_TARGET)

$(BOARD_PREBUILT_DTBOIMAGE): $(MKDTIMG) $(KERNEL_DTBO_CFG) $(KERNEL_BIN)
	$(hide) echo "Building DTBOIMAGE..."
	$(MKDTIMG) cfg_create $@ $(KERNEL_DTBO_CFG) -d $(KERNEL_OBJECTS)

endif #TARGET_PREBUILT_KERNEL
endif #KERNEL_DEFCONFIG