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

set -e

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

#OPTIONS='CONFIG_DEBUG_SECTION_MISMATCH=y'
#OPTIONS='C=1'
OPTIONS="KALLSYMS_EXTRA_PASS=0"
KCFLAGS="-Werror -Wno-error=cpp"

NFS_ROOT=$HOME/src/netboot
TFTP_ROOT=$HOME/tftpboot

#
# Options parsing
#

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

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
			;;
		--*)
			echo "Unrecognized option $option"
			exit 1
			;;
		*)
			platform=$option
			;;
	esac
done

#
# Platform
#

if [[ -z "$platform" ]] ; 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

#
# 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

target_dir=${target_dir:-$NFS_ROOT/$arch_dir}
output_dir=${output_dir:-$PWD/output/$arch_dir}

#
# Parallelize make with twice as many jobs as CPUs
#

num_cpus=$(cat /proc/cpuinfo | grep '^processor\b' | wc -l)
pmake="make -j$((num_cpus*2))"

OPTIONS="KALLSYMS_EXTRA_PASS=0 KCFLAGS='$KCFLAGS'"

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 ARCH=$arch O=$output_dir build_defconfig
	rm $output_dir/arch/$arch/configs/build_defconfig
fi

if [[ $do_menu_config = 1 ]] ; then
	make ARCH=$arch O=$output_dir menuconfig
	exit 0
fi

#
# Compile documentation if requested
#

if [[ $do_compile_doc = 1 ]] ; then
	$pmake ARCH=$arch O=$output_dir DOCBOOKS='' htmldocs
fi

#
# Compile the kernel, modules and DTBs
#

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

eval $pmake ARCH=$arch O=$output_dir CROSS_COMPILE=$cross_compile $OPTIONS \
	$image_kernel $dtbs

grep 'CONFIG_MODULES=y' $output_dir/.config > /dev/null && modules=modules
if [[ x$modules == xmodules ]] ; then
	eval $pmake ARCH=$arch O=$output_dir CROSS_COMPILE=$cross_compile $OPTIONS \
		$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
#

copy_dtbs() {
	local dtb
	local target_dir=$1

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

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

mkdir -p $BOOT_DIR
cp $image_file $BOOT_DIR/

if [[ $image != FIT && $image != CrOS ]] ; then
	copy_dtbs $BOOT_DIR/
fi

if [[ x$modules = xmodules ]] ; then
	$pmake ARCH=$arch O=$output_dir CROSS_COMPILE=$cross_compile INSTALL_MOD_PATH=$target_dir modules_install
	echo "Kernel modules installed to $target_dir/lib/modules/$version"
fi

if [[ $do_package_deb = 1 ]] ; then
	$pmake ARCH=$arch O=$output_dir CROSS_COMPILE=$cross_compile bindeb-pkg
fi

echo "Kernel image available in $image_file"
echo "Build $version completed at $(date)"