Any way to get the fan speed information on Apple Silicon chip?

[thanhdx0]

I'm looking around for fan speed info on my Mac mini M4. It'll be helpful to go along with CPU/GPU temperature.

[joncrangle]

I've been doing some research on getting fan speed readings on Mac silicon without much luck. Apple seems to hide the fan information. I can't find readings (or even min and max RPM) within ioreg -l either. The rust crate that this cli depends most heavily on is sysinfo and it also doesn't contain fan speed info that I was able to find within any of the components.

Macs Fan Control seems to do this somehow, but it is closed source and support is specific to certain versions of the M chip. They must either be using an undocumented private API, or potentially inferring the fan speed using a calculation based on the temperature.

Sorry no luck at the moment. If support gets merged into sysinfo or if someone can create a PR to accomplish this feature I'm open to it.