# Copyright (C) 2012 The CyanogenMod Project
#           (C) 2017-2020 The LineageOS Project
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#      http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.


# Android makefile to build kernel as a part of Android Build
#
# Configuration
# =============
#
# These config vars are usually set in BoardConfig.mk:
#
#   TARGET_KERNEL_CONFIG               = Kernel defconfig
#   TARGET_KERNEL_VARIANT_CONFIG       = Variant defconfig, optional
#   TARGET_KERNEL_SELINUX_CONFIG       = SELinux defconfig, optional
#   TARGET_KERNEL_ADDITIONAL_CONFIG    = Additional defconfig, optional
#
#   TARGET_KERNEL_CLANG_COMPILE        = Compile kernel with clang, defaults to false
#
#   TARGET_KERNEL_CLANG_VERSION        = Clang prebuilts version, optional, defaults to clang-stable
#
#   TARGET_KERNEL_CLANG_PATH           = Clang prebuilts path, optional
#
#   BOARD_KERNEL_IMAGE_NAME            = Built image name
#                                          for ARM use: zImage
#                                          for ARM64 use: Image.gz
#                                          for uncompressed use: Image
#                                          If using an appended DT, append '-dtb'
#                                          to the end of the image name.
#                                          For example, for ARM devices,
#                                          use zImage-dtb instead of zImage.
#
#   BOARD_DTBO_CFG                     = Path to a mkdtboimg.py config file
#
#   BOARD_CUSTOM_DTBOIMG_MK            = Path to a custom dtboimage makefile
#
#   KERNEL_CC                          = The C Compiler used. This is automatically set based
#                                          on whether the clang version is set, optional.
#   KERNEL_LD                          = The Linker used. This is automatically set based
#                                          on whether the clang/gcc version is set, optional.
#
#   KERNEL_CLANG_TRIPLE                = Target triple for clang (e.g. aarch64-linux-gnu-)
#                                          defaults to arm-linux-gnu- for arm
#                                                      aarch64-linux-gnu- for arm64
#                                                      x86_64-linux-gnu- for x86
#
#   NEED_KERNEL_MODULE_ROOT            = Optional, if true, install kernel
#                                          modules in root instead of vendor
#   NEED_KERNEL_MODULE_SYSTEM          = Optional, if true, install kernel
#                                          modules in system instead of vendor
#   NEED_KERNEL_MODULE_VENDOR_OVERLAY  = Optional, if true, install kernel
#                                          modules in vendor_overlay instead of vendor

ifneq ($(TARGET_NO_KERNEL),true)
ifneq ($(TARGET_NO_KERNEL_OVERRIDE),true)

## Externally influenced variables
KERNEL_SRC := $(TARGET_KERNEL_SOURCE)
# kernel configuration - mandatory
KERNEL_DEFCONFIG := $(TARGET_KERNEL_CONFIG)
VARIANT_DEFCONFIG := $(TARGET_KERNEL_VARIANT_CONFIG)
SELINUX_DEFCONFIG := $(TARGET_KERNEL_SELINUX_CONFIG)

## Internal variables
DTC := $(HOST_OUT_EXECUTABLES)/dtc
KERNEL_OUT := $(TARGET_OUT_INTERMEDIATES)/KERNEL_OBJ
DTBO_OUT := $(TARGET_OUT_INTERMEDIATES)/DTBO_OBJ
DTB_OUT := $(TARGET_OUT_INTERMEDIATES)/DTB_OBJ
KERNEL_CONFIG := $(KERNEL_OUT)/.config
KERNEL_RELEASE := $(KERNEL_OUT)/include/config/kernel.release

ifeq ($(KERNEL_ARCH),x86_64)
KERNEL_DEFCONFIG_ARCH := x86
else
KERNEL_DEFCONFIG_ARCH := $(KERNEL_ARCH)
endif
KERNEL_DEFCONFIG_DIR := $(KERNEL_SRC)/arch/$(KERNEL_DEFCONFIG_ARCH)/configs
KERNEL_DEFCONFIG_SRC := $(KERNEL_DEFCONFIG_DIR)/$(KERNEL_DEFCONFIG)

ifneq ($(TARGET_KERNEL_ADDITIONAL_CONFIG),)
KERNEL_ADDITIONAL_CONFIG := $(TARGET_KERNEL_ADDITIONAL_CONFIG)
KERNEL_ADDITIONAL_CONFIG_SRC := $(KERNEL_DEFCONFIG_DIR)/$(KERNEL_ADDITIONAL_CONFIG)
    ifeq ("$(wildcard $(KERNEL_ADDITIONAL_CONFIG_SRC))","")
        $(warning TARGET_KERNEL_ADDITIONAL_CONFIG '$(TARGET_KERNEL_ADDITIONAL_CONFIG)' doesn't exist)
        KERNEL_ADDITIONAL_CONFIG_SRC := /dev/null
    endif
else
    KERNEL_ADDITIONAL_CONFIG_SRC := /dev/null
endif

ifeq ($(BOARD_KERNEL_IMAGE_NAME),)
$(error BOARD_KERNEL_IMAGE_NAME not defined.)
endif
TARGET_PREBUILT_INT_KERNEL := $(KERNEL_OUT)/arch/$(KERNEL_ARCH)/boot/$(BOARD_KERNEL_IMAGE_NAME)

ifeq "$(wildcard $(KERNEL_SRC) )" ""
    ifneq ($(TARGET_PREBUILT_KERNEL),)
        HAS_PREBUILT_KERNEL := true
        NEEDS_KERNEL_COPY := true
    else
        $(foreach cf,$(PRODUCT_COPY_FILES), \
            $(eval _src := $(call word-colon,1,$(cf))) \
            $(eval _dest := $(call word-colon,2,$(cf))) \
            $(ifeq kernel,$(_dest), \
                $(eval HAS_PREBUILT_KERNEL := true)))
    endif

    ifneq ($(HAS_PREBUILT_KERNEL),)
        $(warning ***************************************************************)
        $(warning * Using prebuilt kernel binary instead of source              *)
        $(warning * THIS IS DEPRECATED, AND IS NOT ADVISED.                     *)
        $(warning * Please configure your device to download the kernel         *)
        $(warning * source repository to $(KERNEL_SRC))
        $(warning * for more information                                        *)
        $(warning ***************************************************************)
        FULL_KERNEL_BUILD := false
        KERNEL_BIN := $(TARGET_PREBUILT_KERNEL)
    else
        $(warning ***************************************************************)
        $(warning *                                                             *)
        $(warning * No kernel source found, and no fallback prebuilt defined.   *)
        $(warning * Please make sure your device is properly configured to      *)
        $(warning * download the kernel repository to $(KERNEL_SRC))
        $(warning * and add the TARGET_KERNEL_CONFIG variable to BoardConfig.mk *)
        $(warning *                                                             *)
        $(warning * As an alternative, define the TARGET_PREBUILT_KERNEL        *)
        $(warning * variable with the path to the prebuilt binary kernel image  *)
        $(warning * in your BoardConfig.mk file                                 *)
        $(warning *                                                             *)
        $(warning ***************************************************************)
        $(error "NO KERNEL")
    endif
else
    NEEDS_KERNEL_COPY := true
    ifeq ($(TARGET_KERNEL_CONFIG),)
        $(warning **********************************************************)
        $(warning * Kernel source found, but no configuration was defined  *)
        $(warning * Please add the TARGET_KERNEL_CONFIG variable to your   *)
        $(warning * BoardConfig.mk file                                    *)
        $(warning **********************************************************)
        $(error "NO KERNEL CONFIG")
    else
        FULL_KERNEL_BUILD := true
        KERNEL_BIN := $(TARGET_PREBUILT_INT_KERNEL)
    endif
endif

ifeq ($(FULL_KERNEL_BUILD),true)

ifeq ($(NEED_KERNEL_MODULE_ROOT),true)
KERNEL_MODULES_OUT := $(TARGET_ROOT_OUT)
KERNEL_DEPMOD_STAGING_DIR := $(KERNEL_BUILD_OUT_PREFIX)$(call intermediates-dir-for,PACKAGING,depmod_recovery)
KERNEL_MODULE_MOUNTPOINT :=
else ifeq ($(NEED_KERNEL_MODULE_SYSTEM),true)
KERNEL_MODULES_OUT := $(TARGET_OUT)
KERNEL_DEPMOD_STAGING_DIR := $(KERNEL_BUILD_OUT_PREFIX)$(call intermediates-dir-for,PACKAGING,depmod_system)
KERNEL_MODULE_MOUNTPOINT := system
else ifeq ($(NEED_KERNEL_MODULE_VENDOR_OVERLAY),true)
KERNEL_MODULES_OUT := $(TARGET_OUT_PRODUCT)/vendor_overlay/$(PRODUCT_TARGET_VNDK_VERSION)
KERNEL_DEPMOD_STAGING_DIR := $(KERNEL_BUILD_OUT_PREFIX)$(call intermediates-dir-for,PACKAGING,depmod_product)
KERNEL_MODULE_MOUNTPOINT := vendor
$(INSTALLED_PRODUCTIMAGE_TARGET): $(TARGET_PREBUILT_INT_KERNEL)
else
KERNEL_MODULES_OUT := $(TARGET_OUT_VENDOR)
KERNEL_DEPMOD_STAGING_DIR := $(KERNEL_BUILD_OUT_PREFIX)$(call intermediates-dir-for,PACKAGING,depmod_vendor)
KERNEL_MODULE_MOUNTPOINT := vendor
endif
MODULES_INTERMEDIATES := $(KERNEL_BUILD_OUT_PREFIX)$(call intermediates-dir-for,PACKAGING,kernel_modules)

# Add host bin out dir to path
PATH_OVERRIDE := PATH=$(KERNEL_BUILD_OUT_PREFIX)$(HOST_OUT_EXECUTABLES):$$PATH
ifeq ($(TARGET_KERNEL_CLANG_COMPILE),true)
    ifneq ($(TARGET_KERNEL_CLANG_VERSION),)
        KERNEL_CLANG_VERSION := clang-$(TARGET_KERNEL_CLANG_VERSION)
    else
        # Use the default version of clang if TARGET_KERNEL_CLANG_VERSION hasn't been set by the device config
        KERNEL_CLANG_VERSION := $(LLVM_PREBUILTS_VERSION)
    endif
    TARGET_KERNEL_CLANG_PATH ?= $(BUILD_TOP)/prebuilts/clang/host/$(HOST_PREBUILT_TAG)/$(KERNEL_CLANG_VERSION)
    ifeq ($(KERNEL_ARCH),arm64)
        KERNEL_CLANG_TRIPLE ?= CLANG_TRIPLE=aarch64-linux-gnu-
    else ifeq ($(KERNEL_ARCH),arm)
        KERNEL_CLANG_TRIPLE ?= CLANG_TRIPLE=arm-linux-gnu-
    else ifeq ($(KERNEL_ARCH),x86)
        KERNEL_CLANG_TRIPLE ?= CLANG_TRIPLE=x86_64-linux-gnu-
    endif
    PATH_OVERRIDE += PATH=$(TARGET_KERNEL_CLANG_PATH)/bin:$$PATH LD_LIBRARY_PATH=$(TARGET_KERNEL_CLANG_PATH)/lib64:$$LD_LIBRARY_PATH
    ifeq ($(KERNEL_CC),)
        KERNEL_CC := CC="$(CCACHE_BIN) clang"
    endif
    ifeq ($(KERNEL_LD),)
        KERNEL_LD :=
    endif
endif

ifneq ($(TARGET_KERNEL_MODULES),)
    $(error TARGET_KERNEL_MODULES is no longer supported!)
endif

PATH_OVERRIDE += PATH=$(KERNEL_TOOLCHAIN_PATH_gcc)/bin:$$PATH

# System tools are no longer allowed on 10+
PATH_OVERRIDE += $(TOOLS_PATH_OVERRIDE)

KERNEL_ADDITIONAL_CONFIG_OUT := $(KERNEL_OUT)/.additional_config

# Internal implementation of make-kernel-target
# $(1): output path (The value passed to O=)
# $(2): target to build (eg. defconfig, modules, dtbo.img)
define internal-make-kernel-target
$(PATH_OVERRIDE) $(KERNEL_MAKE_CMD) $(KERNEL_MAKE_FLAGS) -C $(KERNEL_SRC) O=$(KERNEL_BUILD_OUT_PREFIX)$(1) ARCH=$(KERNEL_ARCH) $(KERNEL_CROSS_COMPILE) $(KERNEL_CLANG_TRIPLE) $(KERNEL_CC) $(KERNEL_LD) $(2)
endef

# Make a kernel target
# $(1): The kernel target to build (eg. defconfig, modules, modules_install)
define make-kernel-target
$(call internal-make-kernel-target,$(KERNEL_OUT),$(1))
endef

# Make a DTBO target
# $(1): The DTBO target to build (eg. dtbo.img, defconfig)
define make-dtbo-target
$(call internal-make-kernel-target,$(DTBO_OUT),$(1))
endef

# Make a DTB targets
# $(1): The DTB target to build (eg. dtbs, defconfig)
define make-dtb-target
$(call internal-make-kernel-target,$(DTB_OUT),$(1))
endef

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

$(KERNEL_ADDITIONAL_CONFIG_OUT): $(KERNEL_OUT)
	$(hide) cmp -s $(KERNEL_ADDITIONAL_CONFIG_SRC) $@ || cp $(KERNEL_ADDITIONAL_CONFIG_SRC) $@;

$(KERNEL_CONFIG): $(KERNEL_DEFCONFIG_SRC) $(KERNEL_ADDITIONAL_CONFIG_OUT)
	@echo "Building Kernel Config"
	$(call make-kernel-target,VARIANT_DEFCONFIG=$(VARIANT_DEFCONFIG) SELINUX_DEFCONFIG=$(SELINUX_DEFCONFIG) $(KERNEL_DEFCONFIG))
	$(hide) if [ ! -z "$(KERNEL_CONFIG_OVERRIDE)" ]; then \
			echo "Overriding kernel config with '$(KERNEL_CONFIG_OVERRIDE)'"; \
			echo $(KERNEL_CONFIG_OVERRIDE) >> $(KERNEL_OUT)/.config; \
			$(call make-kernel-target,oldconfig); \
		fi
	# Create defconfig build artifact
	$(call make-kernel-target,savedefconfig)
	$(hide) if [ ! -z "$(KERNEL_ADDITIONAL_CONFIG)" ]; then \
			echo "Using additional config '$(KERNEL_ADDITIONAL_CONFIG)'"; \
			$(KERNEL_SRC)/scripts/kconfig/merge_config.sh -m -O $(KERNEL_OUT) $(KERNEL_OUT)/.config $(KERNEL_SRC)/arch/$(KERNEL_ARCH)/configs/$(KERNEL_ADDITIONAL_CONFIG); \
			$(call make-kernel-target,KCONFIG_ALLCONFIG=$(KERNEL_OUT)/.config alldefconfig); \
		fi

$(TARGET_PREBUILT_INT_KERNEL): $(KERNEL_CONFIG) $(DEPMOD) $(DTC)
	@echo "Building Kernel Image ($(BOARD_KERNEL_IMAGE_NAME))"
	$(call make-kernel-target,$(BOARD_KERNEL_IMAGE_NAME))
	$(hide) if grep -q '^CONFIG_OF=y' $(KERNEL_CONFIG); then \
			echo "Building DTBs"; \
			$(call make-kernel-target,dtbs); \
		fi
	$(hide) if grep -q '=m' $(KERNEL_CONFIG); then \
			echo "Building Kernel Modules"; \
			$(call make-kernel-target,modules) || exit "$$?"; \
			echo "Installing Kernel Modules"; \
			$(call make-kernel-target,INSTALL_MOD_PATH=$(MODULES_INTERMEDIATES) INSTALL_MOD_STRIP=1 modules_install); \
			kernel_release=$$(cat $(KERNEL_RELEASE)) \
			kernel_modules_dir=$(MODULES_INTERMEDIATES)/lib/modules/$$kernel_release \
			$(foreach s, $(TARGET_MODULE_ALIASES),\
				$(eval p := $(subst :,$(space),$(s))) \
				; mv $$(find $$kernel_modules_dir -name $(word 1,$(p))) $$kernel_modules_dir/$(word 2,$(p))); \
			modules=$$(find $$kernel_modules_dir -type f -name '*.ko'); \
			($(call build-image-kernel-modules,$$modules,$(KERNEL_MODULES_OUT),$(KERNEL_MODULE_MOUNTPOINT)/,$(KERNEL_DEPMOD_STAGING_DIR))); \
		fi

.PHONY: kerneltags
kerneltags: $(KERNEL_CONFIG)
	$(call make-kernel-target,tags)

.PHONY: kernelsavedefconfig alldefconfig

kernelsavedefconfig: $(KERNEL_OUT)
	$(call make-kernel-target,$(KERNEL_DEFCONFIG))
	env KCONFIG_NOTIMESTAMP=true \
		 $(call make-kernel-target,savedefconfig)
	cp $(KERNEL_OUT)/defconfig $(KERNEL_DEFCONFIG_SRC)

alldefconfig: $(KERNEL_OUT)
	env KCONFIG_NOTIMESTAMP=true \
		 $(call make-kernel-target,alldefconfig)

ifeq (true,$(filter true, $(TARGET_NEEDS_DTBOIMAGE) $(BOARD_KERNEL_SEPARATED_DTBO)))
ifneq ($(BOARD_CUSTOM_DTBOIMG_MK),)
include $(BOARD_CUSTOM_DTBOIMG_MK)
else
MKDTIMG := $(HOST_OUT_EXECUTABLES)/mkdtimg$(HOST_EXECUTABLE_SUFFIX)
MKDTBOIMG := $(HOST_OUT_EXECUTABLES)/mkdtboimg.py$(HOST_EXECUTABLE_SUFFIX)
$(BOARD_PREBUILT_DTBOIMAGE): $(DTC) $(MKDTIMG) $(MKDTBOIMG)
ifeq ($(BOARD_KERNEL_SEPARATED_DTBO),true)
$(BOARD_PREBUILT_DTBOIMAGE):
	@echo "Building dtbo.img"
	$(call make-dtbo-target,$(KERNEL_DEFCONFIG))
	$(call make-dtbo-target,dtbs)
ifdef BOARD_DTBO_CFG
	$(MKDTBOIMG) cfg_create $@ $(BOARD_DTBO_CFG) -d $(DTBO_OUT)/arch/$(KERNEL_ARCH)/boot/dts
else
	$(MKDTBOIMG) create $@ --page_size=$(BOARD_KERNEL_PAGESIZE) $(shell find $(DTBO_OUT)/arch/$(KERNEL_ARCH)/boot/dts -type f -name "*.dtbo" | sort)
endif
else
$(BOARD_PREBUILT_DTBOIMAGE):
	@echo "Building dtbo.img"
	$(call make-dtbo-target,$(KERNEL_DEFCONFIG))
	$(call make-dtbo-target,dtbo.img)
endif # BOARD_KERNEL_SEPARATED_DTBO
endif # BOARD_CUSTOM_DTBOIMG_MK
endif # TARGET_NEEDS_DTBOIMAGE/BOARD_KERNEL_SEPARATED_DTBO

ifeq ($(BOARD_INCLUDE_DTB_IN_BOOTIMG),true)
ifeq ($(BOARD_PREBUILT_DTBIMAGE_DIR),)
$(INSTALLED_DTBIMAGE_TARGET): $(DTC)
	@echo "Building dtb.img"
	$(call make-dtb-target,$(KERNEL_DEFCONFIG))
	$(call make-dtb-target,dtbs)
	cat $(shell find $(DTB_OUT)/arch/$(KERNEL_ARCH)/boot/dts -type f -name "*.dtb" | sort) > $@
endif # !BOARD_PREBUILT_DTBIMAGE_DIR
endif # BOARD_INCLUDE_DTB_IN_BOOTIMG

endif # FULL_KERNEL_BUILD

## Install it

ifeq ($(NEEDS_KERNEL_COPY),true)
file := $(INSTALLED_KERNEL_TARGET)
ALL_PREBUILT += $(file)
$(file) : $(KERNEL_BIN) | $(ACP)
	$(transform-prebuilt-to-target)

ALL_PREBUILT += $(INSTALLED_KERNEL_TARGET)
endif

.PHONY: kernel
kernel: $(INSTALLED_KERNEL_TARGET)

.PHONY: dtboimage
dtboimage: $(INSTALLED_DTBOIMAGE_TARGET)

.PHONY: dtbimage
dtbimage: $(INSTALLED_DTBIMAGE_TARGET)

endif # TARGET_NO_KERNEL_OVERRIDE
endif # TARGET_NO_KERNEL