[swetland]

The CPU itself (Core Complex, including cache, irq controller, etc) is documented by SiFive:

https://www.sifive.com/cores/u74-mc

Unfortunately there appears to be no detailed documentation at all (unless you count a pile of Linux and bootloader patches, which I don't) for the peripherals, etc, outside of the core complex on the SoC:

https://doc-en.rvspace.org/Doc_Center/jh7110.html

[MisterTea]

> unless you count a pile of Linux and bootloader patches, which I don't

This is what drives me crazy. Vendor claims "open source" which means an outdated linux image and the source code is wrapped up inside of a megalith build monstrosity like penguintronix or yocto. Utter junk these things are.

[snvzz]

OpenSBI patches are already upstream, and u-boot being reviewed for merging.

It is not anywhere as bad as you're picturing it.