Documentation:
- CP2112 Datasheet https://www.silabs.com/documents/public/data-sheets/cp2112-datasheet.pdf
- AN495: CP2112 Interface Specification https://www.silabs.com/documents/public/application-notes/an495-cp2112-interface-specification.pdf
- CP2112 Errata https://www.silabs.com/documents/public/errata/cp2112-errata.pdf
This is an alternative implementation to D25359.
There is a monolithic driver that implements all functions.
Some things could be made nicer because of that, but there is some ugliness too
as gpiobus and iicbus like when thier controllers have specific device names.
Otherwise, some extra work is needed to make them attach.