# SPDX-License-Identifier: GPL-2.0-only

ifneq ($(KERNELRELEASE),)
include Kbuild

else

# PATH
KROOT=$(shell expr match $(PWD) '\(.*/kernel-[0-9.]*/\)')
ROOT_DIR=$(realpath $(KROOT)/..)
OUT_DIR=$(PWD)/out

srctree=$(KROOT)
src=$(subst $(KROOT),,$(PWD))

ifeq ($(KDIR),)
KDIR:=$(shell ls -d $(ROOT_DIR)/out_mgk_*/target/product/mgk_*/obj/KERNEL_OBJ/kernel-*/)
endif

$(info KDIR = "$(KDIR)")

## reference config file to fetch clang version
CONFIG=$(KROOT)build.config.constants
CLANG_VERSION=$(shell cat $(CONFIG) | grep CLANG_VERSION | cut -d'=' -f 2)

COMMON_CONFIG=$(KROOT)build.config.common
CLANG_PREBUILT_BIN=$(shell cat $(COMMON_CONFIG) | grep CLANG_PREBUILT_BIN | cut -d'=' -f 2)
CLANG_PATH=$(ROOT_DIR)/$(subst $${CLANG_VERSION},$(CLANG_VERSION),$(CLANG_PREBUILT_BIN))

#$(info CLANG_VERSION = $(CLANG_VERSION))
#$(info CLANG_PREBUILT_BIN = $(CLANG_PREBUILT_BIN))
$(info CLANG_PATH = $(CLANG_PATH))

# Toolchain
TARGET_ARCH=arm64
CROSS_COMPILE:=aarch64-linux-gnu-
CROSS_COMPILE_COMPAT:=arm-linux-gnueabi-
CC=$(CLANG_PATH)/clang
LD=$(CLANG_PATH)/ld.lld
AR=$(CLANG_PATH)/llvm-ar
NM=$(CLANG_PATH)/llvm-nm
STRIP=$(CLANG_PATH)/llvm-strip
OBJCOPY=$(CLANG_PATH)/llvm-objcopy
OBJDUMP=$(CLANG_PATH)/llvm-objdump
READELF=$(CLANG_PATH)/llvm-readelf

HOSTCC=$(CLANG_PATH)/clang
HOSTAR=$(CLANG_PATH)/llvm-ar
HOSTLD=$(CLANG_PATH)/ld.lld

CFLAGS=-Wall LLVM=1 LLVM_IAS=1

# disable BTF as workaround for "pahole: invalid operation -J" issue
EXT_CONFIG="\
    CONFIG_DEBUG_INFO_BTF_MODULES= \
    "

### DEFINE ###
define kernel-make
+$(MAKE) -C $(KDIR) \
    ARCH=$(TARGET_ARCH) \
    CROSS_COMPILE=$(CROSS_COMPILE) \
    CROSS_COMPILE_COMPAT=$(CROSS_COMPILE_COMPAT) \
    CFLAGS=$(CFLAGS) \
    CC=$(CC) \
    LD=$(LD) \
    AR=$(AR) \
    STRIP=$(STRIP) \
    OBJCOPY=$(OBJCOPY) \
    OBJDUMP=$(OBJDUMP) \
    READELF=$(READELF) \
    HOSTCC=$(HOSTCC) \
    HOSTAR=$(HOSTAR) \
    HOSTLD=$(HOSTLD) \
    M=$(PWD)
endef

N := 1
define check-patch
+git format-patch --stdout -$(N) HEAD | $(KROOT)/scripts/checkpatch.pl \
    --show-types --max-line-length=100 \
    --ignore=DT_SCHEMA_BINDING_PATCH,DT_SPLIT_BINDING_PATCH,GERRIT_CHANGE_ID,FILE_PATH_CHANGES,MEMORY_BARRIER,NEW_TYPEDEFS,VOLATILE,MISSING_SIGN_OFF,COMMIT_LOG_LONG_LINE
endef

.PHONY: all build clean check-env

all: check-env build install list_ko
build:
	$(kernel-make) modules $(EXT_CONFIG)
install: build
	$(kernel-make) modules_install INSTALL_MOD_STRIP=1 INSTALL_MOD_PATH=$(OUT_DIR)
clean:
	$(kernel-make) clean
	# clean *.lds
	find -name "*.lds" -exec rm {} \;
	# clean out
	rm -rf $(OUT_DIR)
check-env:
ifndef KDIR
	$(error KDIR (prebuilt kernel path) is undefined)
endif
$(info prebuilt kernel = $(KDIR))

checkpatch:
	$(check-patch)
list_ko: install
	@echo "list of ko:"
	@find -name *.ko -exec ls -l {} \;

endif