#!/bin/bash
# SPDX-License-Identifier: GPL-2.0+

set -e

kbuild_root=$(dirname $(readlink -f "$0"))

declare -A cross_compile
declare -A extra_kcflags
declare -A target_root

if [[ -r $kbuild_root/config.sh ]] ; then
	source $kbuild_root/config.sh || exit 1
fi

#kbuild_options='CONFIG_DEBUG_SECTION_MISMATCH=y'
#kbuild_options='C=1'
kbuild_options="KALLSYMS_EXTRA_PASS=0"

get_kernel_version() {
	local version=$(cat Makefile | grep '^VERSION = ' | sed 's/.* = //')
	local patchlevel=$(cat Makefile | grep '^PATCHLEVEL = ' | sed 's/.* = //')
	local sublevel=$(cat Makefile | grep '^SUBLEVEL = ' | sed 's/.* = //')
	echo "$version.$patchlevel.$sublevel"
}

version=$(get_kernel_version)

#
# Options parsing
#

do_compile_doc=0
do_menu_config=0
do_package_deb=0
opt_bootloader=
opt_cmdline_file=
opt_defconfig=
opt_make_opts=

while [[ $# != 0 ]] ; do
	option=$1
	shift

	case $option in
		--bootloader)
			opt_bootloader=$1
			if [[ ! -r $opt_bootloader ]] ; then
				echo "Boot loader file $opt_bootloader is not readable"
				exit 1
			fi
			shift
			;;
		--cmdline)
			opt_cmdline_file=$1
			if [[ ! -r $opt_cmdline_file ]] ; then
				echo "Command line file $opt_cmdline_file is not readable"
				exit 1
			fi
			shift
			;;
		--config)
			do_menu_config=1
			;;
		--deb)
			do_package_deb=1
			;;
		--defconfig)
			opt_defconfig=$1
			if [[ ! -r $opt_defconfig ]] ; then
				echo "defconfig file $opt_defconfig is not readable"
				exit 1
			fi
			shift
			;;
		--doc)
			do_compile_doc=1
			;;
		--)
			platform=auto
			;;
		--*)
			echo "Unrecognized option $option"
			exit 1
			;;
		*)
			if [[ -z "$platform" ]] ; then
				platform=$option
			else
				opt_make_opts="$option $opt_make_opts"
			fi
			;;
	esac
done

#
# Platform
#

kcflags="-Werror -Wno-error=cpp"

if [[ -z "$platform" || "$platform" == "auto" ]] ; then
	for f in $kbuild_root/platforms/*.sh ; do
		pattern=$(cat $f | grep "dir_pattern=" | head -1)
		pattern=${pattern/#dir_pattern=/}
		if [[ -n "$pattern" ]] ; then
			echo $PWD | grep -q "$pattern" || continue
			platform=$(basename -s .sh $f)
			break
		fi
	done
fi

if [[ ! -r "$kbuild_root/platforms/$platform.sh" ]] ; then
	echo "Unknown platform '$platform'. Supported platforms are"
	for f in $kbuild_root/platforms/*.sh ; do
		echo "- $(basename -s .sh $f)"
	done
	exit 1
fi

source "${kbuild_root}/platforms/$platform.sh" || exit 1

# Apply version-specific kcflags, useful to suppress warnings based on the
# kernel version.
[[ -z "${extra_kcflags[$version]+_}" ]] || kcflags="$kcflags ${extra_kcflags[$version]}"

#
# Architecture
#

if [[ ! -r "$kbuild_root/arch/$arch.sh" ]] ; then
	echo "Unknown architecture '$arch'. Supported architectures are"
	for f in $kbuild_root/arch/*.sh ; do
		echo "- $(basename -s .sh $f)"
	done
	exit 1
fi

source "${kbuild_root}/arch/$arch.sh" || exit 1

# Override the output directory for ARM for historical reasons
case $arch in
	arm)
		output_dir=$PWD/output/arm32
		;;
	*)
		output_dir=$PWD/output/$arch
		;;
esac

#
# Build environment and tools
#

num_cpus=$(cat /proc/cpuinfo | grep '^processor\b' | wc -l)
make="make ARCH=$arch O=$output_dir CROSS_COMPILE=${cross_compile[$arch]} ${extra_make_args}"
pmake="$make -j$((num_cpus*2)) $opt_make_opts"

echo "Compiling for platform $platform with $num_cpus CPUs"

mkdir -p $output_dir/

if [[ -n "$opt_defconfig" ]] ; then
	mkdir -p $output_dir/arch/$arch/configs/
	cp $opt_defconfig $output_dir/arch/$arch/configs/build_defconfig
	$make build_defconfig
	rm $output_dir/arch/$arch/configs/build_defconfig
fi

if [[ $do_menu_config == 1 ]] ; then
	$make menuconfig
	exit 0
fi

#
# Compile documentation if requested
#

if [[ $do_compile_doc == 1 ]] ; then
	$pmake DOCBOOKS='' htmldocs
fi

#
# Compile the kernel, modules and DTBs
#

kernel_dtbs=
for dtb in $dtbs ; do
	dtb=${dtb/:*/}
	kernel_dtbs="$kernel_dtbs $dtb"
done

$pmake $kbuild_options KCFLAGS="$kcflags" $image_kernel $kernel_dtbs

grep 'CONFIG_MODULES=y' $output_dir/.config > /dev/null && modules=modules
if [[ x$modules == xmodules ]] ; then
	$pmake $kbuild_options KCFLAGS="$kcflags" $modules
fi

version=$(cat $output_dir/include/generated/utsrelease.h | cut -d '"' -f 2)

#
# Create the image
#

if [[ -r "$kbuild_root/images/$image.sh" ]] ; then
	source "${kbuild_root}/images/$image.sh" || exit 1
	eval make_${image}_image
else
	image_file=$output_dir/arch/$arch/boot/$image
fi

#
# Copy the files to their destination directories.
#
# The kernel image and DTBs are copied to both $target_dir/boot and $tftp_dir
# (if available). When the image format is CrOS, installation to $tftp_dir is
# skipped as Chrome OS devices can't boot from TFTP.
#
# The modules are installed to $target_dir if available, or to
# $output_dir/modules otherwise.
#

target_dir=${target_dir:-${target_root[$arch]}}
tftp_dir=${tftp_dir:-$tftp_root/$platform}

copy_dtbs() {
	local dest_dir=$1
	local dtb

	if [[ $image == FIT || $image == CrOS ]] ; then
		return
	fi

	for dtb in $dtbs ; do
		local src=${dtb/:*/}
		local dst=${dtb/*:/}
		dst=${dst/*\//}

		cp $output_dir/arch/${arch}/boot/dts/$src* $dest_dir/$dst
	done
}

if [[ -d "$target_dir" ]] ; then
	mkdir -p $target_dir/boot
	cp $image_file $target_dir/boot/
	copy_dtbs $target_dir/boot/
fi

if [[ $image != CrOS && -d "$tftp_dir" ]] ; then
	cp $image_file $tftp_dir/
	copy_dtbs $tftp_dir/
fi

if [[ x$modules == xmodules ]] ; then
	mod_path=${target_dir:-$output_dir/modules}
	mkdir -p $mod_path
	$pmake INSTALL_MOD_PATH=$mod_path modules_install
fi

#
# Create the Debian package if requested
#

if [[ $do_package_deb == 1 ]] ; then
	$pmake bindeb-pkg
fi

#
# Print status and terminate
#

echo "Kernel image available in $image_file"
if [[ x$modules == xmodules ]] ; then
	echo "Kernel modules installed to $mod_path/lib/modules/$version"
fi
echo "Build $version completed at $(date)"