ath79: add Senao 'failsafe' sysupgrade procedure

Use a similar upgrade method for sysupgrade.bin, like factory.bin,
for Senao boards with the tar.gz OEM upgrade platform,
and 'failsafe' image which is loaded on checksum failure.

This is inspired by the OEM upgrade script /etc/fwupgrade.sh
and the existing platforms for dual-boot Senao boards.

Previously, if the real kernel was damaged or missing
the only way to recover was with UART serial console,
because the OKLI lzma-loader is programmed to halt.

uboot did not detect cases where kernel or rootfs is damaged
and boots OKLI instead of the failsafe image,
because the checksums stored in uboot environment
did not include the real kernel and rootfs space.

Now, the stored checksums include the space for both
the lzma-loader, kernel, and rootfs.
Therefore, these boards are now practically unbrickable.

Also, the factory.bin and sysupgrade.bin are now the same,
except for image metadata.
This allows for flashing OEM image directly from openwrt
as well as flashing openwrt image directly from OEM.

Make 'loader' partition writable so that it can be updated
during a sysupgrade.

tested with
ENS202EXT v1
EAP1200H
EAP350 v1
EAP600
ECB350 v1
ECB600
ENH202 v1

Signed-off-by: Michael Pratt <mcpratt@pm.me>

2 files changed, 78 insertions, 0 deletions

diff --git a/target/linux/ath79/generic/base-files/lib/upgrade/failsafe_datachk.sh b/target/linux/ath79/generic/base-files/lib/upgrade/failsafe_datachk.sh
new file mode 100644
index 0000000000..de84233de1
--- /dev/null
+++ b/target/linux/ath79/generic/base-files/lib/upgrade/failsafe_datachk.sh
@@ -0,0 +1,64 @@
+# U-Boot with the datachk patchset requires image sizes, offsets,
+# and checksums to be provided in the U-Boot environment.
+# This script is based on the dualboot version for devices that come with 2 OS partitions.
+# For Senao boards with a "failsafe" partition image, the process is almost the same.
+# Instead of booting a secondary instalation on checksum failure,
+# the failsafe image is booted instead.
+# These boards also use the OKLI lzma kernel loader and mtd-concat
+# So the kernel check is for the loader, the rootfs check is for kernel + rootfs
+
+platform_do_upgrade_failsafe_datachk() {
+	local setenv_script="/tmp/fw_env_upgrade"
+
+	local flash_base=0x9f000000
+
+	local kernel_mtd=$(find_mtd_index ${KERNEL_PART:-kernel})
+	local rootfs_mtd=$(find_mtd_index ${ROOTFS_PART:-rootfs})
+
+	local kernel_offset=$(cat /sys/class/mtd/mtd${kernel_mtd}/offset)
+	local rootfs_offset=$(cat /sys/class/mtd/mtd${rootfs_mtd}/offset)
+
+	if [ -n "$IMAGE_LIST" ]; then
+		KERNEL_FILE=$($IMAGE_LIST | grep $KERNEL_FILE)
+		ROOTFS_FILE=$($IMAGE_LIST | grep $ROOTFS_FILE)
+	fi
+
+	local kernel_size=$($IMAGE_CMD $KERNEL_FILE | wc -c)
+	local rootfs_size=$($IMAGE_CMD $ROOTFS_FILE | wc -c)
+
+	# rootfs without JFFS2
+	local rootfs_blocks=$((rootfs_size / 4096))
+	rootfs_size=$((rootfs_blocks * 4096))
+
+	local kernel_md5=$($IMAGE_CMD $KERNEL_FILE | md5sum | cut -d ' ' -f1)
+	local rootfs_md5=$($IMAGE_CMD $ROOTFS_FILE | dd bs=4k count=$rootfs_blocks iflag=fullblock | md5sum | cut -d ' ' -f1)
+
+	# prepare new u-boot-env vars
+	printf "vmlinux_start_addr 0x%08x\n" $((flash_base + kernel_offset)) >> $setenv_script
+	printf "vmlinux_size 0x%08x\n" ${kernel_size} >> $setenv_script
+	printf "vmlinux_checksum %s\n" ${kernel_md5} >> $setenv_script
+
+	printf "rootfs_start_addr 0x%08x\n" $((flash_base + rootfs_offset)) >> $setenv_script
+	printf "rootfs_size 0x%08x\n" ${rootfs_size} >> $setenv_script
+	printf "rootfs_checksum %s\n" ${rootfs_md5} >> $setenv_script
+
+	# store u-boot-env
+	mkdir -p /var/lock
+	fw_setenv -s $setenv_script || {
+		echo 'failed to update U-Boot environment'
+		exit 1
+	}
+
+	# sysupgrade
+	sleep 2
+	sync
+	echo 3 > /proc/sys/vm/drop_caches
+	$IMAGE_CMD $KERNEL_FILE | mtd $MTD_ARGS write - ${KERNEL_PART:-kernel}
+	sleep 2
+	sync
+	if [ -n "$UPGRADE_BACKUP" ]; then
+		$IMAGE_CMD $ROOTFS_FILE | mtd $MTD_ARGS $MTD_CONFIG_ARGS -j $UPGRADE_BACKUP write - ${ROOTFS_PART:-rootfs}
+	else
+		$IMAGE_CMD $ROOTFS_FILE | mtd $MTD_ARGS write - ${ROOTFS_PART:-rootfs}
+	fi
+}
diff --git a/target/linux/ath79/generic/base-files/lib/upgrade/platform.sh b/target/linux/ath79/generic/base-files/lib/upgrade/platform.sh
index 575761d079..19699332fc 100644
--- a/target/linux/ath79/generic/base-files/lib/upgrade/platform.sh
+++ b/target/linux/ath79/generic/base-files/lib/upgrade/platform.sh
@@ -47,6 +47,20 @@ platform_do_upgrade() {
 	adtran,bsap1840)
 		redboot_fis_do_upgrade "$1" vmlinux_2
 		;;
+	engenius,eap1200h|\
+	engenius,eap300-v2|\
+	engenius,eap600|\
+	engenius,ecb600|\
+	engenius,ens202ext-v1|\
+	engenius,enstationac-v1)
+		IMAGE_LIST="tar tzf $1"
+		IMAGE_CMD="tar xzOf $1"
+		KERNEL_PART="loader"
+		ROOTFS_PART="fwconcat0"
+		KERNEL_FILE="uImage-lzma.bin"
+		ROOTFS_FILE="root.squashfs"
+		platform_do_upgrade_failsafe_datachk "$1"
+		;;
 	jjplus,ja76pf2)
 		redboot_fis_do_upgrade "$1" linux
 		;;