#!/bin/sh

# Copyright (C) 2006  Joey Hess  <joeyh@debian.org>
# Copyright (C) 2006, 2007, 2008  Martin Michlmayr <tbm@cyrius.com>

# This code is covered by the GNU General Public License (GPLv2 or higher)

set -e

error() {
	echo "$@" >&2
	exit 1
}

check_mtd() {
	if [ ! -e /proc/mtd ]; then
		error "/proc/mtd doesn't exist"
	fi
}

mtdblock() {
	grep "\"$1\"" /proc/mtd | cut -d: -f 1 | sed 's/mtd/\/dev\/mtdblock/'
}

mtdsize() {
	size=$(grep "\"$1\"" /proc/mtd | cut -d " " -f 2)
	printf "%d" 0x$size
}

check_subarch() {
        if [ -n "$subarch" ] && [ "$subarch" != "$1" ]; then
		echo "Kernel $kfile does not match your subarchitecture" >&2
		echo "$1, therefore not writing it to flash." >&2
	fi
}

check_size() {
	if [ $2 -gt $3 ]; then
		error "The $1 doesn't fit in flash."
	fi
}

# See http://www.nslu2-linux.org/wiki/Info/BootFlash -- the NSLU2 uses a
# 16 byte MTD header, the first four bytes (big endian) give the length of
# the remainder of the image, and the remaining bytes are zero.  Generate
# this header.
sercomm_header() {
	perl -e 'print pack("N4", shift)' "$1"
}

nslu2_swap() {
	if [ "$little_endian" ]; then
		devio "<<"$1 "xp $,4"
	else
		cat $1
	fi
}


if [ -n "$1" ]; then
	kvers="$1"
	kfile=/boot/vmlinuz-$kvers
	ifile=/boot/initrd.img-$kvers
	desc="Debian kernel $1"
else
	if [ -e /vmlinuz ]; then
		kfile=/vmlinuz
		ifile=/initrd.img
	elif [ -e /boot/vmlinuz ]; then
		kfile=/boot/vmlinuz
		ifile=/boot/initrd.img
	else
		error "Cannot find a default kernel in /vmlinuz or /boot/vmlinuz"
	fi
	desc="Debian kernel"
fi

if [ ! -e $kfile ] || [ ! -e $ifile ]; then
	error "Can't find $kfile and $ifile"
fi
kfilesize=$(wc -c $kfile | awk '{print $1}')
ifilesize=$(wc -c $ifile | awk '{print $1}')

# Extract the subarchitecture from the kernel name
if [ -L "$kfile" ]; then
    kfile=$(readlink -e "$kfile")
fi
subarch=$(echo "$kfile" | sed -e 's/.*-//')

machine=$(grep "^Hardware" /proc/cpuinfo | sed 's/Hardware\s*:\s*//')
case "$machine" in
	"Linksys NSLU2")
		check_subarch "ixp4xx"
#		case "$(dpkg --print-architecture)" in
#			arm|armel)
#				little_endian=1
#			;;
#			armeb)
#				little_endian=0
#			;;
#		esac
		little_endian=1
		check_mtd
		fismtd=$(mtdblock "FIS directory")
		if [ -z "$fismtd" ]; then
			error "Cannot find mtd FIS directory"
		fi
		kmtd=$(mtdblock Kernel)
		if [ -z "$kmtd" ]; then
			error "Cannot find mtd partition 'Kernel'"
		fi
		kmtdsize=$(mtdsize "Kernel")
		check_size "kernel" $(($kfilesize + 16 + 16)) $kmtdsize
		imtd=$(mtdblock Ramdisk)
		if [ -z "$imtd" ]; then
			error "Cannot find mtd partition 'Ramdisk'"
		fi
		imtdsize=$(mtdsize "Ramdisk")
		check_size "ramdisk" $(($ifilesize + 16)) $imtdsize
		# The following devio magic parses the FIS directory to
		# obtain the size, offset and name of each partition.  This
		# used used to obtain the offset of the Kernel partition.
		offset=$(echo "$(devio "<<$fismtd" '
			<= $ 0x20000 -
			L= 0x1000
			$( 1
				# 0xff byte in name[0] ends the partition table
				$? @ 255 =
				# output size base name
				<= f15+
				.= b 0xfffffff &
				<= f4+
				.= b
				pf "%lu %lu "
				<= f28-
				cp 16
				pn
				<= f240+
				L= L256-
			$) L255>')" |
			while read a b c; do
				if [ "$c" = "Kernel" ]; then
					echo $b
				fi
			done)
		# The Kernel partition, starting at $offset, is divided into
		# two areas at $boundary.  We therefore need to split the
		# kernel into two and write them to flash with two Sercomm
		# headers.
		boundary=1441792 # 0x00160000
		ksize1=$(expr $boundary - $offset - 16)
		tmp=$(tempfile)
		printf "Flashing kernel: $kfile\n" >&2
		(
			sercomm_header $(expr $kfilesize + 16)
			dd if=$kfile of=$tmp bs=$ksize1 count=1 2>/dev/null
			nslu2_swap $tmp
			sercomm_header 131072
			dd if=$kfile of=$tmp ibs=$ksize1 skip=1 2>/dev/null
			nslu2_swap $tmp
			rm -f $tmp
		) > "$kmtd" || error "failed."
		echo "done." >&2
		printf "Flashing initramfs: $ifile\n" >&2
		dd if=$ifile of=$tmp ibs=$(($imtdsize - 16)) conv=sync 2>/dev/null
		(
			sercomm_header $ifilesize
			nslu2_swap $tmp
			rm -f $tmp
		) > $imtd || error "failed."
		echo "done." >&2
	;;
	"QNAP TS-109/TS-209" | "QNAP TS-409")
		check_subarch "orion5x"
		check_mtd
		imtd=$(mtdblock "RootFS1")
		if [ -z "$imtd" ]; then
			error "Cannot find mtd partition 'RootFS1'"
		fi
		imtdsize=$(mtdsize "RootFS1")
		check_size "RootFS1" $ifilesize $imtdsize
		kmtd=$(mtdblock Kernel)
		if [ -z "$kmtd" ]; then
			error "Cannot find mtd partition 'Kernel'"
		fi
		kmtdsize=$(mtdsize "Kernel")
		check_size "Kernel" $(($kfilesize + 8 + 64)) $kmtdsize
		printf "Generating kernel u-boot image... " >&2
		tmp=$(tempfile)
		case "$machine" in
			"QNAP TS-109/TS-209")
				devio > $tmp 'wl 0xe3a01c06,4' 'wl 0xe381101d,4'
			;;
			"QNAP TS-409")
				devio > $tmp 'wl 0xe3a01c06,4' 'wl 0xe3811041,4'
			;;
		esac
		cat $kfile >> $tmp
		mkimage -A arm -O linux -T kernel -C none -a 0x00008000 \
			-e 0x00008000 -n "$desc" -d $tmp $tmp.uboot >&2 1>/dev/null
		echo "done." >&2
		printf "Flashing kernel... \n" >&2
		cat $tmp.uboot > $kmtd || error "failed."
		echo "done." >&2
		rm -f $tmp.uboot $tmp
		printf "Flashing initramfs... \n" >&2
		pad=$(expr $imtdsize - $ifilesize)
		(
			cat $ifile
			dd if=/dev/zero bs=$pad count=1 2>/dev/null
		) > $imtd || error "failed."
		echo "done." >&2
	;;
	"Thecus N2100")
		check_subarch "iop32x"
		check_mtd
		imtd=$(mtdblock ramdisk)
		if [ -z "$imtd" ]; then
			error "Cannot find mtd partition 'ramdisk'"
		fi
		imtdsize=$(mtdsize "ramdisk")
		check_size "ramdisk" $ifilesize $imtdsize
		kmtd=$(mtdblock kernel)
		if [ -z "$kmtd" ]; then
			error "Cannot find mtd partition 'kernel'"
		fi
		kmtdsize=$(mtdsize "kernel")
		check_size "kernel" $(($kfilesize + 8)) $kmtdsize
		printf "Flashing kernel... \n" >&2
		(
			devio 'wl 0xe3a01c04,4' 'wl 0xe381104d,4'
			cat $kfile
		) > $kmtd || error "failed."
		echo "done." >&2
		printf "Flashing initramfs... \n" >&2
		pad=$(expr $imtdsize - $ifilesize)
		(
			cat $ifile
			dd if=/dev/zero bs=$pad count=1 2>/dev/null
		) > $imtd || error "failed."
		echo "done." >&2
	;;
	*)
		error "Unsupported platform."
	;;
esac