For working with locked packages (the ones which must be upgraded through compilation because of using custom options)

#!/bin/sh
# filename: pkg-lock-outdated

pkg query -e '%k = 1' %o | while read pkgorig; do
  pkg version -ovL => -O "$pkgorig"
done

The script above is to list locked packages which need upgrading. And to upgrade everything at once (and sit in front of PC waiting for whole process)

#!/bin/sh

listfile="/tmp/pkgforupgrade.$(date '+%Y%m%d%H%M%S')"
pkg-lock-outdated | cut -f 1 -d '<' > "$listfile"

while read <&3 outdated; do
  pkg unlock "$outdated"
  portmaster "$outdated"
  pkg lock "$outdated"
done 3< "$listfile"

rm -f "$listfile"

There’s another alternative of unlocking all packages at once, run batched portmaster, and lock them all again.