RPi4B, POE+. Fan

From: Brian Scott <bscott_at_bunyatech.com.au>
Date: Tue, 11 Jan 2022 10:50:45 UTC
Hi List,

Is there a known method to get the fan running on the rpi-poe+ board 
under FreeBSD?

It looks like it is controlled completely by the kernel in Linux land. 
Adding the rpi-poe dtb overlay has no effect on FreeBSD so I'm guessing 
there is no driver for it.

 From what I've read, its controlled by something on the iic bus used 
for HAT identification. Beyond that, information seems to get very 
scarce. The Linux driver operates it by sending messages to the 
firmware. This would be a lot more tricky than just sending commands to 
an iic device from userland and beyond my hacking skills.

CPU temperature currently is: dev.cpu.0.temperature: 86.6C so I would 
quite happy if I could just turn it on.

Running FreeBSD 13 Stable with a snapshot from 16 December 2021. System 
is loosely based on nanobsd.

Cheers,


Brian