mediatek: mt7623: prepare for full sysupgrade support on UniElec U7623

An upcoming commit will add a full system image for U7623 which will
contain the MBR partition table and U-Boot too.

That contrasts with the current image which only owns the eMMC from
sector 0xa00 onwards, and must start with a legacy uImage.

Prepare for sysupgrade to the new images, and cope with the fact that
the recovery partition will be /dev/mmcblk0p2 instead of /dev/mmcblk0p1
after the upgrade.

This commit could potentially be backported to 19.07 to allow for direct
sysupgrade to the new image layout.

Signed-off-by: David Woodhouse <dwmw2@infradead.org>

target/linux/mediatek/mt7623/base-files/lib/preinit/79_move_config

@@ -10,7 +10,11 @@ move_config() {
 		partnum=2
 		;;
 	unielec,u7623-02-emmc-512m)
-		partnum=1
+		if grep -q root=/dev/mmcblk0p2 /proc/cmdline; then
+			partnum=1;
+		else
+			partnum=2;
+		fi
 		;;
 	*)
 		return 1

target/linux/mediatek/mt7623/base-files/lib/upgrade/platform.sh

@@ -1,9 +1,15 @@
-platform_do_upgrade() {
-	local board=$(board_name)
 
-	case "$board" in
+REQUIRE_IMAGE_METADATA=1
-	bananapi,bpi-r2)
+
-		local diskdev partdev diff
+# Full system upgrade including preloader for MediaTek SoCs on eMMC or SD
+mtk_mmc_full_upgrade() {
+	local diskdev partdev diff oldrecovery
+
+	if grep -q root=/dev/mmcblk0p2 /proc/cmdline; then
+	    oldrecovery=1
+	else
+	    oldrecovery=2
+	fi
 
 	export_bootdevice && export_partdevice diskdev 0 || {
 		echo "Unable to determine upgrade device"
@@ -12,7 +18,7 @@ platform_do_upgrade() {
 
 	#Keep the persistent random mac address (if it exists)
 	mkdir -p /tmp/recovery
-		export_partdevice recoverydev 2
+	export_partdevice recoverydev $oldrecovery
 	if mount -o rw,noatime "/dev/$recoverydev" -tvfat /tmp/recovery; then
 		[ -f "/tmp/recovery/mac_addr" ] && cp /tmp/recovery/mac_addr /tmp/
 		umount /tmp/recovery
@@ -36,12 +42,12 @@ platform_do_upgrade() {
 	if [ -n "$diff" ]; then
 		get_image "$@" | dd of="/dev/$diskdev" bs=4096 conv=fsync
 
-			# Separate removal and addtion is necessary; otherwise, partition 1
+		# Separate removal and addition is necessary; otherwise, partition 1
 		# will be missing if it overlaps with the old partition 2
 		partx -d - "/dev/$diskdev"
 		partx -a - "/dev/$diskdev"
 	else
-			#iterate over each partition from the image and write it to the boot disk
+		# iterate over each partition from the image and write it to the boot disk
 		while read part start size; do
 			part="$(($part - 2))"
 			if export_partdevice partdev $part; then
@@ -57,6 +63,7 @@ platform_do_upgrade() {
 		get_image "$@" | dd of="/dev/$diskdev" bs=1 skip=440 count=4 seek=440 conv=fsync
 	fi
 
+	export_partdevice recoverydev 2
 	if mount -o rw,noatime "/dev/$recoverydev" -t vfat /tmp/recovery; then
 		[ -f "/tmp/mac_addr" ] && cp /tmp/mac_addr /tmp/recovery
 
@@ -69,24 +76,38 @@ platform_do_upgrade() {
 		sync
 		umount /tmp/recovery
 	fi
+}
+
+platform_do_upgrade() {
+	local board=$(board_name)
+
+	case "$board" in
+	bananapi,bpi-r2)
+		mtk_mmc_full_upgrade "$1"
 		;;
 
 	unielec,u7623-02-emmc-512m)
-		#Keep the persisten random mac address (if it exists)
+		local magic="$(get_magic_long "$1")"
+		if [ "$magic" = "53444d4d" ]; then
+			mtk_mmc_full_upgrade "$1"
+		else # Old partial image starting with uImage
+			# Keep the persistent random mac address (if it exists)
+			recoverydev=mmcblk0p1
 			mkdir -p /tmp/recovery
-		mount -o rw,noatime /dev/mmcblk0p1 /tmp/recovery
+			mount -o rw,noatime /dev/$recoverydev /tmp/recovery
 			[ -f "/tmp/recovery/mac_addr" ] && \
 				mv -f /tmp/recovery/mac_addr /tmp/
 			umount /tmp/recovery
 
-		#1310720 is the offset in bytes from the start of eMMC and to
+			# 1310720 is the offset in bytes from the start of eMMC and to
-		#the location of the kernel (2560 512 byte sectors)
+			# the location of the kernel (2560 512 byte sectors)
 			get_image "$1" | dd of=/dev/mmcblk0 bs=1310720 seek=1 conv=fsync
 
-		mount -o rw,noatime /dev/mmcblk0p1 /tmp/recovery
+			mount -o rw,noatime /dev/$recoverydev /tmp/recovery
 			[ -f "/tmp/mac_addr" ] && mv -f /tmp/mac_addr /tmp/recovery
 			sync
 			umount /tmp/recovery
+		fi
 		;;
 	*)
 		default_do_upgrade "$1"
@@ -133,10 +154,21 @@ platform_check_image() {
 		fi
 		;;
 	unielec,u7623-02-emmc-512m)
+		# Can always upgrade to the new-style full image
+		[ "$magic" = "53444d4d" ] && return 0
+
+		# Legacy uImage directly at 0xA00 on the eMMC.
 		[ "$magic" != "27051956" ] && {
 			echo "Invalid image type."
 			return 1
 		}
+		rootpart=$(cat /proc/cmdline)
+		rootpart="${rootpart##*root=}"
+		rootpart="${rootpart%% *}"
+		[ "$rootpart" != "/dev/mmcblk0p2" ] && {
+			echo "Cannot downgrade to legacy image."
+			return 1
+		}
 		return 0
 		;;
 	*)
@@ -148,25 +180,18 @@ platform_check_image() {
 	return 0
 }
 
-platform_copy_config_emmc() {
-	local partdev
-
-	if export_bootdevice && export_partdevice partdev $1; then
-		mkdir -p /recovery
-		mount -o rw,noatime "/dev/$partdev" -t vfat /recovery
-		cp -af "$UPGRADE_BACKUP" "/recovery/$BACKUP_FILE"
-		sync
-		umount /recovery
-	fi
-}
-
 platform_copy_config() {
 	case "$(board_name)" in
-	bananapi,bpi-r2)
+	bananapi,bpi-r2|\
-		platform_copy_config_emmc 2
-		;;
 	unielec,u7623-02-emmc-512m)
-		platform_copy_config_emmc 1
+		# platform_do_upgrade() will have set $recoverydev
+		if [ -n "$recoverydev" ]; then
+			mkdir -p /tmp/recovery
+			mount -o rw,noatime "/dev/$recoverydev" -t vfat /tmp/recovery
+			cp -af "$UPGRADE_BACKUP" "/tmp/recovery/$BACKUP_FILE"
+			sync
+			umount /tmp/recovery
+		fi
 		;;
 	esac
 }