mediatek: mt7623: re-write sysupgrade uImage.FIT on MMC

Re-reading the partition table doesn't work reliably, it fails if
anything on the device is still in use and it's not trivial to prevent
every possible case of a block device still being in use somehow.

Therefore, instead of relying on the in-kernel partition parser to know
where to write the configuration backup, use OpenWrt's format-agnostic
fwtool to strip off all metadata from the image and count its blocks
while writing. In that way we can know where to write the config backup
without needing the kernel to parse the MBR and FIT structures.

Signed-off-by: Daniel Golle <daniel@makrotopia.org>

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

@@ -1,6 +1,6 @@
 
 REQUIRE_IMAGE_METADATA=1
-RAMFS_COPY_BIN='blockdev'
+RAMFS_COPY_BIN='fwtool'
 
 # Full system upgrade including preloader for MediaTek SoCs on eMMC or SD
 mtk_mmc_full_upgrade() {
@@ -84,19 +84,14 @@ platform_do_upgrade() {
 
 	case "$board" in
 	bananapi,bpi-r2)
+		sync
 		export_bootdevice
-		export_partdevice rootdev 0
-		blockdev --rereadpt /dev/$rootdev || return 1
 		export_partdevice fitpart 3
 		[ "$fitpart" ] || return 1
-		dd if=/dev/zero of=$fitpart bs=4096 count=1 2>/dev/null
-		blockdev --rereadpt /dev/$rootdev
-		get_image "$1" | dd of=$fitpart
-		blockdev --rereadpt /dev/$rootdev
-		local datapart=$(find_mmc_part "rootfs_data" $rootdev)
-		[ "$datapart" ] || return 0
-		dd if=/dev/zero of=$datapart bs=4096 count=1 2>/dev/null
-		echo $datapart > /tmp/sysupgrade.datapart
+		export UPGRADE_MMC_PARTDEV="/dev/$fitpart"
+		export UPGRADE_MMC_IMAGE_BLOCKS=$(($(get_image "$1" | fwtool -i /dev/null -T - | dd of=$UPGRADE_MMC_PARTDEV bs=512 2>&1 | grep "records out" | cut -d' ' -f1)))
+		[ "$UPGRADE_MMC_IMAGE_BLOCKS" ] || return 0
+		dd if=/dev/zero of=$UPGRADE_MMC_PARTDEV bs=512 seek=$UPGRADE_MMC_IMAGE_BLOCKS count=8
 		;;
 
 	unielec,u7623-02-emmc-512m)
@@ -172,10 +167,12 @@ platform_check_image() {
 }
 
 platform_copy_config_mmc() {
-	[ -e "$UPGRADE_BACKUP" ] || return
-	local datapart=$(cat /tmp/sysupgrade.datapart)
-	[ "$datapart" ] || echo "no rootfs_data partition, cannot keep configuration." >&2
-	dd if="$UPGRADE_BACKUP" of=$datapart
+	if [ ! -e "$UPGRADE_BACKUP" ] ||
+	   [ ! -e "$UPGRADE_MMC_PARTDEV" ] ||
+	   [ ! "$UPGRADE_MMC_IMAGE_BLOCKS" ]; then
+		return
+	fi
+	dd if="$UPGRADE_BACKUP" of="$UPGRADE_MMC_PARTDEV" bs=512 seek=$UPGRADE_MMC_IMAGE_BLOCKS
 	sync
 }
 

target/linux/mediatek/mt7623/target.mk

@@ -9,7 +9,7 @@ CPU_TYPE:=cortex-a7
 CPU_SUBTYPE:=neon-vfpv4
 KERNELNAME:=Image dtbs zImage
 FEATURES+=display usbgadget
-DEFAULT_PACKAGES+=blockdev uboot-envtools
+DEFAULT_PACKAGES+=uboot-envtools
 
 define Target/Description
 	Build firmware images for MediaTek mt7623 ARM based boards.