ipq60xx: add linksys MR7350 sysupgrade support

target/linux/ipq60xx/base-files/lib/upgrade/platform.sh

@@ -5,12 +5,93 @@ REQUIRE_IMAGE_METADATA=1
 RAMFS_COPY_BIN='fw_printenv fw_setenv'
 RAMFS_COPY_DATA='/etc/fw_env.config /var/lock/fw_printenv.lock'
 
+linksys_get_boot_part() {
+	local cur_boot_part
+	local args
+
+	# Try to find rootfs from kernel arguments
+	read -r args < /proc/cmdline
+	for arg in $args; do
+		local ubi_mtd_arg=${arg#ubi.mtd=}
+		case "$ubi_mtd_arg" in
+		rootfs|alt_rootfs)
+			echo "$ubi_mtd_arg"
+			return
+		;;
+		esac
+	done
+
+	# Fallback to u-boot env (e.g. when running sysfs)
+	cur_boot_part="$(/usr/sbin/fw_printenv -n boot_part)"
+	case $cur_boot_part in
+	1)
+		echo rootfs
+		;;
+	2|*)
+		echo alt_rootfs
+		;;
+	esac
+}
+
+linksys_prepare_ubi() {
+	local oem_ubivol
+	local mtdnum
+	local ubidev
+
+	mtdnum=$(find_mtd_index "$CI_UBIPART")
+	if [ ! "$mtdnum" ]; then
+		return
+	fi
+
+	ubidev=$(nand_find_ubi "$CI_UBIPART")
+	if [ ! "$ubidev" ]; then
+		ubiattach --mtdn="$mtdnum"
+		ubidev=$(nand_find_ubi "$CI_UBIPART")
+	fi
+
+	if [ "$ubidev" ]; then
+		oem_ubivol=$(nand_find_volume "$ubidev" squashfs)
+		[ "$oem_ubivol" ] && ubirmvol "/dev/$ubidev" --name=squashfs
+	fi
+}
+
+linksys_do_upgrade() {
+	local current_boot_slot
+	local new_boot_part
+
+	current_boot_slot=$(linksys_get_boot_part)
+	case $current_boot_slot in
+	rootfs)
+		CI_UBIPART="alt_rootfs"
+		CI_KERNPART="alt_kernel"
+		new_boot_part=2
+	;;
+	alt_rootfs)
+		CI_UBIPART="rootfs"
+		CI_KERNPART="kernel"
+		new_boot_part=1
+	;;
+	esac
+	echo "Updating mtd=$CI_UBIPART, boot_part=$new_boot_part"
+
+	fw_setenv -s - <<-EOF
+		boot_part $new_boot_part
+		auto_recovery yes
+	EOF
+
+	linksys_prepare_ubi
+	nand_do_upgrade "$1"
+}
+
 platform_check_image() {
 	return 0;
 }
 
 platform_do_upgrade() {
 	case "$(board_name)" in
+	linksys,mr7350)
+		linksys_do_upgrade "$1"
+		;;
 	cmiot,ax18|\
 	zn,m2)
 		nand_do_upgrade "$1"