added A/B partition update

resources/scripts/ab_active

@@ -0,0 +1,11 @@
+ #!/bin/bash
+set -e
+
+# get current partition index
+current_idx=$(rdev | sed 's#/dev/mmcblk0p\([^ ]*\).*#\1#')
+
+if [ $current_idx -eq 2 ]; then
+    echo "Active partition: A"
+else
+    echo "Active partition: B"
+fi

resources/scripts/ab_flash

@@ -0,0 +1,40 @@
+ #!/bin/bash
+set -e
+
+image_file=$1
+
+if [ -z $image_file ]; then
+    echo "USAGE: $0 [IMAGE_PATH]"
+    return 1
+fi
+
+# change to directory containing update file
+cd $(dirname $image_file)
+
+# check integrity of image
+sha256sum -c ${image_file}.sha256
+
+# get current partition index
+current_idx=$(rdev | sed 's#/dev/mmcblk0p\([^ ]*\).*#\1#')
+
+if [ $current_idx -eq 2 ]; then
+    echo "Start update for partition B"
+    flash_idx=3
+else
+    echo "Start update for partition A"
+    flash_idx=2
+fi
+
+flash_device="/dev/mmcblk0p${flash_idx}"
+
+# flash device
+gunzip -c ${image_file} | dd of=${flash_device} status=progress
+
+
+# switch active partition
+mount -o remount,rw /uboot
+fw_setenv boot_partition ${flash_idx}
+sync
+mount -o remount,ro /uboot
+
+echo "Update complete -> please reboot"