Hardware related stuff on the PC Engines apu board

I2C

The I2C bus of the AMD A55E Hudson-1 FCH does not work with the i2c-piix4 kernel driver the Hudson-2 uses. I found a patched driver here that does the job. I'm currently trying to get the patch into upstream mainline.
Update 2014-01-19: the apu's I2C bus is supported out of the box as of kernel 3.12-rc1.

apu front LEDs

I wrote a kernel module to access the 3 front LEDs on the apu board and a small daemon to use LEDs 2 and 3 as network up/downstream indicators. Download is here, just run

make

I use LED 1 as a load indicator:

modprobe ledtrig_default_on; modprobe ledtrig_heartbeat
echo heartbeat > /sys/class/leds/apu:1/trigger

and run apuled like this:

apuled eth0 -c nrt -f

Update 2015-02-17: thanks to Mark Schank we now have two implementations of a reset switch driver!