Hello,
I’ve created two sets of device tree files.
One for easy runtime gpio muxing:
https://github.com/nomel/beaglebone/tree/master/gpio-header
And one to enable the gpio-led interface on any gpio:
https://github.com/nomel/beaglebone/tree/master/led-header
For a quick example, it only takes two lines to set up P9.16 to show cpu activity:
echo led-P9.16 > /sys/devices/bone_capemgr.*/slots
echo cpu0 > trigger /sys/class/leds/leds:P9.16/trigger
See the readme files for examples.