#!/bin/sh

set -u
set -e

PROGNAME=$(basename $0)

usage()
{
    echo "Create an SD card that boots on an i.MX6DL SABRESD board."
    echo "It is supposed to work also for the i.MX6Q SABRESD board, but"
    echo "it this is not tested."
    echo
    echo "Note: all data on the the card will be completely deleted!"
    echo "Use with care!"
    echo "Superuser permissions may be required to write to the device."
    echo
    echo "Usage: ${PROGNAME} <sd_block_device>"
    echo "Arguments:"
    echo "  <sd_block_device>     The device to be written to"
    echo
    echo "Example: ${PROGNAME} /dev/mmcblk0"
    echo
}

if [ $# -ne 1 ]; then
    usage
    exit 1
fi

if [ $(id -u) -ne 0 ]; then
    echo "${PROGNAME} must be run as root"
    exit 1
fi

DEV=${1}

# The partition name prefix depends on the device name:
# - /dev/sde -> /dev/sde1
# - /dev/mmcblk0 -> /dev/mmcblk0p1
if echo ${DEV}|grep -q mmcblk ; then
    PART="p"
else
    PART=""
fi

PART1=${DEV}${PART}1
PART2=${DEV}${PART}2

# Unmount the partitions if mounted
umount ${PART1} || true
umount ${PART2} || true

# First, clear the card
dd if=/dev/zero of=${DEV} bs=1M count=20

sync

# Partition the card.
# SD layout for i.MX6 boot:
# - Bootloader at offset 1024
# - FAT partition starting at 1MB offset, containing uImage and *.dtb
# - ext2/3 partition formatted as ext2 or ext3, containing the root filesystem.
sfdisk ${DEV} <<EOF
32,480,b
512,,L
EOF

sync

# Copy the bootloader at offset 1024
dd if=output/images/u-boot.imx of=${DEV} obs=512 seek=2

# Prepare a temp dir for mounting partitions
TMPDIR=$(mktemp -d)

# FAT partition: kernel and DTBs
mkfs.vfat ${PART1}
mount ${PART1} ${TMPDIR}
cp output/images/uImage ${TMPDIR}/
cp output/images/*.dtb  ${TMPDIR}/
sync
umount ${TMPDIR}

# ext2 partition: root filesystem
mkfs.ext2 ${PART2}
mount ${PART2} ${TMPDIR}
tar -C ${TMPDIR}/ -xf output/images/rootfs.tar
sync
umount ${TMPDIR}

# Cleanup
rmdir ${TMPDIR}
sync
echo Done