bcm4908: add sysupgrade support

It supports flashing OpenWrt images (bootfs & UBI upgrade) as well as
vendor images (whole MTD partition write).

Upgrading cferom is unsupported. It requires copying device specific
data (like MAC) to target image before flashing.

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>

target/linux/bcm4908/base-files/lib/upgrade/platform.sh

@@ -0,0 +1,213 @@
+# SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause
+
+RAMFS_COPY_BIN="bcm4908img"
+
+PART_NAME=firmware
+
+# $(1): file to read from
+# $(2): offset in bytes
+# $(3): length in bytes
+get_content() {
+	dd if="$1" skip=$2 bs=1 count=$3 2>/dev/null
+}
+
+# $(1): file to read from
+# $(2): offset in bytes
+get_hex_u32_be() {
+	dd if="$1" skip=$2 bs=1 count=4 2>/dev/null | hexdump -v -e '1/1 "%02x"'
+}
+
+platform_expected_image() {
+	local machine=$(board_name)
+
+	case "$machine" in
+		asus,gt-ac5300)			echo "asus GT-AC5300";;
+		netgear,r8000p)			echo "chk U12H359T00_NETGEAR";;
+		tplink,archer-c2300-v1)		echo "";;
+	esac
+}
+
+platform_identify() {
+	local magic
+	local size
+
+	magic=$(get_hex_u32_be "$1" 0)
+	case "$magic" in
+		2a23245e)
+			echo "chk"
+			return
+		;;
+	esac
+
+	size=$(wc -c "$1" | cut -d ' ' -f 1)
+
+	magic=$(get_content "$1" $((size - 20 - 64 + 8)) 12)
+	case "$magic" in
+		GT-AC5300)
+			echo "asus"
+			return
+		;;
+	esac
+
+	echo "unknown"
+}
+
+platform_check_image() {
+	[ "$#" -gt 1 ] && return 1
+
+	local expected_image=$(platform_expected_image)
+	local error=0
+
+	bcm4908img info -i "$1" > /dev/null || {
+		echo "Failed to validate BCM4908 image" >&2
+		notify_firmware_broken
+		return 1
+	}
+
+	bcm4908img bootfs -i "$1" ls | grep -q "1-openwrt" || {
+		# OpenWrt images have 1-openwrt dummy file in the bootfs.
+		# Don't allow backup if it's missing
+		notify_firmware_no_backup
+	}
+
+	case "$(platform_identify "$1")" in
+		asus)
+			local size=$(wc -c "$1" | cut -d ' ' -f 1)
+			local productid=$(get_content "$1" $((size - 20 - 64 + 8)) 12)
+
+			[ -n "$expected_image" -a "asus $productid" != "$expected_image" ] && {
+				echo "Firmware productid mismatch ($productid)" >&2
+				error=1
+			}
+		;;
+		chk)
+			local header_len=$((0x$(get_hex_u32_be "$1" 4)))
+			local board_id_len=$(($header_len - 40))
+			local board_id=$(dd if="$1" skip=40 bs=1 count=$board_id_len 2>/dev/null | hexdump -v -e '1/1 "%c"')
+
+			[ -n "$expected_image" -a "chk $board_id" != "$expected_image" ] && {
+				echo "Firmware board_id mismatch ($board_id)" >&2
+				error=1
+			}
+		;;
+		*)
+			echo "Invalid image type. Please use firmware specific for this device." >&2
+			notify_firmware_broken
+			error=1
+		;;
+	esac
+
+	return $error
+}
+
+# $1: cferam index increment value
+platform_calc_new_cferam() {
+	local inc="$1"
+	local dir="/tmp/sysupgrade-bcm4908"
+
+	local mtd=$(find_mtd_part bootfs)
+	[ -z "$mtd" ] && {
+		echo "Failed to find bootfs partition" >&2
+		return
+	}
+
+	rm -fR $dir
+	mkdir -p $dir
+	mount -t jffs2 -o ro $mtd $dir || {
+		echo "Failed to mount bootfs partition $mtd" >&2
+		rm -fr $dir
+		return
+	}
+
+	local idx=$(ls $dir/cferam.??? | sed -n 's/.*cferam\.\(\d\d\d\)/\1/p')
+	[ -z "$idx" ] && {
+		echo "Failed to find cferam current index" >&2
+		rm -fr $dir
+		return
+	}
+
+	umount $dir
+	rm -fr $dir
+
+	idx=$(((idx + inc) % 1000))
+
+	echo $(printf "cferam.%03d" $idx)
+}
+
+platform_do_upgrade_ubi() {
+	local dir="/tmp/sysupgrade-bcm4908"
+	local inc=1
+
+	# Verify new bootfs size
+	local mtd_bootfs_size=$(grep "\"bootfs\"" /proc/mtd | sed "s/mtd[0-9]*:[ \t]*\([^ \t]*\).*/\1/")
+	[ -z "$mtd_bootfs_size" ] && {
+		echo "Unable to find \"bootfs\" partition size"
+		return
+	}
+	mtd_bootfs_size=$((0x$mtd_bootfs_size))
+	local img_bootfs_size=$(bcm4908img extract -i "$1" -t bootfs | wc -c)
+	[ $img_bootfs_size -gt $mtd_bootfs_size ] && {
+		echo "New bootfs doesn't fit MTD partition."
+		return
+	}
+
+	# Find cferam name for new firmware
+	# For UBI we always flash "firmware" so don't increase cferam index if
+	# there is "fallback". That could result in cferam.999 & cferam.001
+	[ -n "$(find_mtd_index backup)" -o -n "$(find_mtd_index fallback)" ] && inc=0
+	local cferam=$(platform_calc_new_cferam $inc)
+	[ -z "$cferam" ] && exit 1
+
+	# Prepare new firmware
+	bcm4908img bootfs -i "$1" mv cferam.000 $cferam || {
+		echo "Failed to rename cferam.000 to $cferam" >&2
+		exit 1
+	}
+
+	# Extract rootfs for further flashing
+	rm -fr $dir
+	mkdir -p $dir
+	bcm4908img extract -i "$1" -t rootfs > $dir/root || {
+		echo "Failed to extract rootfs" >&2
+		rm -fr $dir
+		exit 1
+	}
+
+	# Flash bootfs MTD partition with new one
+	mtd erase bootfs || {
+		echo "Failed to erase bootfs" >&2
+		rm -fr $dir
+		exit 1
+	}
+	bcm4908img extract -i "$1" -t bootfs | mtd write - bootfs || {
+		echo "Failed to flash bootfs" >&2
+		rm -fr $dir
+		exit 1
+	}
+
+	nand_do_upgrade $dir/root
+}
+
+platform_do_upgrade() {
+	# Try NAND aware UBI upgrade for OpenWrt images
+	# Below call will exit on success
+	bcm4908img bootfs -i "$1" ls | grep -q "1-openwrt" && platform_do_upgrade_ubi "$1"
+
+	echo "Writing whole image to NAND flash. All erase counters will be lost."
+
+	# Find cferam name for new firmware
+	local cferam=$(platform_calc_new_cferam 1)
+	[ -z "$cferam" ] && exit 1
+
+	# Prepare new firmware
+	bcm4908img bootfs -i "$1" mv cferam.000 $cferam || {
+		echo "Failed to rename cferam.000 to $cferam" >&2
+		exit 1
+	}
+
+	# Jush flash firmware partition as is
+	[ -n "$(find_mtd_index backup)" ] && PART_NAME=backup
+	[ -n "$(find_mtd_index fallback)" ] && PART_NAME=fallback
+	mtd erase $PART_NAME
+	default_do_upgrade "$1" "bcm4908img extract -t firmware"
+}