Yeah, that model does match my real world experience.
Regarding all the other stuff that the EC may or may not handle (e.g. lid switch and power button LED), how would one go about figuring it out? My ideas would be:
- Look at EC drivers for older lenovo laptops, if they exist.
- Try probing various addresses on the i2c bus.
- Some sort of behavioral analysis of the windows driver. (E.g. somehow log the i2c bus traffic.)