+#
+# Copyright (C) 2015 OpenWrt.org
+#
+
+. /lib/functions.sh
+#Note: this code also uses some functions from nand.sh, but it is expected to be run by nand.sh, so we are not
+#sourcing it explicitly here
+
+UBNT_ERX_KERNEL_INDEX_OFFSET=160
+
+ubnt_get_target_kernel() {
+ local factory_mtd=$1
+ local current_kernel_index=$(hexdump -s $UBNT_ERX_KERNEL_INDEX_OFFSET -n 1 -e '/1 "%X "' ${factory_mtd})
+
+ if [ $current_kernel_index == "0" ]; then
+ echo 'kernel2'
+ elif [ $current_kernel_index == "1" ]; then
+ echo 'kernel1'
+ fi
+}
+
+ubnt_update_target_kernel() {
+ local factory_mtd=$1
+ local kernel_part=$2
+
+ local new_kernel_index
+ if [ $kernel_part == "kernel1" ]; then
+ new_kernel_index="\x00"
+ elif [ $kernel_part == "kernel2" ]; then
+ new_kernel_index="\x01"
+ else
+ echo 'Unknown kernel image index' >&2
+ return 1
+ fi
+
+ if ! (echo -e $new_kernel_index | dd of=${factory_mtd} bs=1 count=1 seek=$UBNT_ERX_KERNEL_INDEX_OFFSET); then
+ echo 'Failed to update kernel bootup index' >&2
+ return 1
+ fi
+}
+
+platform_upgrade_ubnt_erx() {
+ local factory_mtd=$(find_mtd_part factory)
+ if [ -z "$factory_mtd" ]; then
+ echo "cannot find factory partition" >&2
+ exit 1
+ fi
+
+ local kernel_part="$(ubnt_get_target_kernel ${factory_mtd})"
+ if [ -z "$kernel_part" ]; then
+ echo "cannot find factory partition" >&2
+ exit 1
+ fi
+
+ # This is a global defined in nand.sh, sets partition kernel will be flashed into
+ CI_KERNPART=${kernel_part}
+
+ #Remove volume possibly left over from stock firmware
+ local ubidev="$( nand_find_ubi "$CI_UBIPART" )"
+ if [ -z "$ubidev" ]; then
+ local mtdnum="$( find_mtd_index "$CI_UBIPART" )"
+ if [ -z "$mtdnum" ]; then
+ echo "cannot find ubi mtd partition $CI_UBIPART" >&2
+ exit 1
+ fi
+ ubiattach -m "$mtdnum"
+ sync
+ ubidev="$( nand_find_ubi "$CI_UBIPART" )"
+ fi
+ if [ -n "$ubidev" ]; then
+ local troot_ubivol="$( nand_find_volume $ubidev troot )"
+ [ -n "$troot_ubivol" ] && ubirmvol /dev/$ubidev -N troot || true
+ fi
+
+ ubnt_update_target_kernel ${factory_mtd} ${kernel_part} || exit 1
+}