There is an effort to write linux drivers for peripherals in Pine Ox64 https://wiki.pine64.org/wiki/Ox64, the chip(BL808) documentation is not that great. But would be a good exercise to write some drivers.
What kind of documentation one would normally need for this sort of project? If the documentation are not great or missing something, is there steps that could be taken to figure out the chips functions in order to implement them?