#!/bin/bash
#
# Reference: <<i.MX Linux® User's Guide.pdf>>
#
# SD Card partition layout:   1 Sector= 512B
#
# +-------------------------------+-----------------------+---------------------------------+
# |         Start  Address        |         Size          |           Usage                 |
# +-------------------------------+-----------------------+---------------------------------+
# |             0x0               |   32 sectors(16K)     |  Reserved for partition table   |
# +-------------------------------+-----------------------+---------------------------------+
# |      2 sector(1K, 0x400)      |  20414 sectors(9M+)   |     i.MX6ULL  u-boot image      |
# +-------------------------------+-----------------------+---------------------------------+
# |  20480 sector(10M, 0xa00000)  | 204800 sectors(100MB) |      FAT32 Boot partition       |
# +-------------------------------+-----------------------+---------------------------------+
# | 225280 sector(110M,0x6e00000) |    Remaining Space    |     EXT4 filesystem for rootfs  |
# +-------------------------------+-----------------------+---------------------------------+
#

PRJ_PATH=`pwd`
IMAGE_PATH=${PRJ_PATH}/bin/

BOARD=imx6ull

# rootfs should be buildroot or stretch/buster/bullseye for debian system
ROOTFS=buildroot

# linux kernel tarball path and branch
TAR_PATH=/home/guowenxue/imx6ull/bsp/tarball

BOOT=emmc

IMAGE_NAME=linuxsys_${BOARD}_${ROOTFS}.img
if [ $ROOTFS == buildroot ] ; then
    IMAGE_SIZE=512
else
    IMAGE_SIZE=2048
fi

# 1 sector - for i.MX6 or i.MX7
UBOOT_OFSET=1

# BootRom(U-boot) Size 10MB:  20480 Sectors * 512B
UBOOT_SIZE=10

# vfat boot partition size
BOOT_SIZE=100


IMG_UBOOT=${IMAGE_PATH}/u-boot-imx6ull-emmc.imx
IMG_KERNEL=${IMAGE_PATH}/Image
IMG_DTB=${IMAGE_PATH}/imx6ull-emmc.dtb
ROOTFS_TAR=${TAR_PATH}/rootfs_${ROOTFS}.tar.bz2

MNT_POINT=./mnt
LOOP_DEV=`losetup  -f | cut -d/ -f3`

set -u
set -e

if [ `id -u` != 0 ] ; then
    echo "ERROR: This shell script must run as root"
    exit 0;
fi

trap 'exit_handler' EXIT
function exit_handler()
{
    echo "Shell script exit now, do some clean work"
    echo ""

    mountpoint $MNT_POINT > /dev/null 2>&1
    if [ $? == 0 ] ; then
        umount ${MNT_POINT}
    fi

    rm -rf ${MNT_POINT}

    if [ -L /dev/mapper/${LOOP_DEV}p1 ] ; then
        kpartx -dv /dev/${LOOP_DEV}
    fi

    losetup -a | grep "${LOOP_DEV}" > /dev/null 2>&1
    if [ $? == 0 ]  ; then
        losetup -d /dev/${LOOP_DEV}
    fi
}

STAGE=0
function msg_banner()
{
    STAGE=`expr $STAGE + 1`

    echo ""
    echo "+---------------------------------------------+"
    printf " Stage $STAGE: $1\n"
    echo "+---------------------------------------------+"
    echo ""
}


function generate_image()
{
    # system image block count by block=512k
    BLOCK_CNT=`expr 2 \* ${IMAGE_SIZE}`

    # FAT32 boot partition start/end address in MB
    BOOT_START=${UBOOT_SIZE}
    BOOT_END=`expr ${BOOT_START} + ${BOOT_SIZE}`

    msg_banner " <${STAGE}> Generate system image "

    dd if=/dev/zero of=${IMAGE_NAME} bs=512k count=${BLOCK_CNT}  && sync
    chmod a+x ${IMAGE_NAME}

    msg_banner " <${STAGE}> Partition system image "

    parted ${IMAGE_NAME} mklabel msdos
    parted ${IMAGE_NAME} mkpart primary fat32 ${BOOT_START}M ${BOOT_END}M
    parted ${IMAGE_NAME} mkpart primary ext4 ${BOOT_END}M 100%

    sync
}


function format_partition()
{
    msg_banner " <${STAGE}> losetup image on $LOOP_DEV"

    losetup /dev/${LOOP_DEV}  ${IMAGE_NAME}
    kpartx -av /dev/${LOOP_DEV}

    msg_banner " <${STAGE}> Format system image partition"
    mkfs.vfat /dev/mapper/${LOOP_DEV}p1
    mkfs.ext4 /dev/mapper/${LOOP_DEV}p2
    sync
}

function install_sysimg()
{
    msg_banner " <${STAGE}> Install u-boot image"
    sudo dd if=${IMG_UBOOT} of=${IMAGE_NAME} bs=1k seek=${UBOOT_OFSET} conv=notrunc,sync

    msg_banner " <${STAGE}> Install linux kernel image"

    mkdir -p ${MNT_POINT}
    mount -t vfat /dev/mapper/${LOOP_DEV}p1 ${MNT_POINT}

    set -x
    cp ${IMG_KERNEL} ${MNT_POINT}
    cp ${IMG_DTB}    ${MNT_POINT}
    sync
    set +x

    umount ${MNT_POINT}
}

function install_rootfs()
{
    msg_banner " <${STAGE}> Install root filesystem "

    if [ ! -f ${ROOTFS_TAR} ] ; then
        echo "ERROR: rootfs tarball file '${ROOTFS_TAR}' not exist..."
        exit ;
    fi

    mount -t ext4 /dev/mapper/${LOOP_DEV}p2 ${MNT_POINT}
    tar -xjf ${ROOTFS_TAR} -C ${MNT_POINT} && sync

    umount ${MNT_POINT}
}

mkdir -p ${MNT_POINT}

generate_image

format_partition

install_sysimg

install_rootfs

rm -rf ${MNT_POINT}