[OpenPower-Firmware] Hardware documentation

[Marty E. Plummer]

Hello all.

So, I've gotten to the point I believe I've got code execution working
(at the very least in theory; still need to do *something* easily
detectable like writing a string to the scratch register) and am
investigating what happens during the following isteps. I'm having a
hard time following the execution of the c++ code past kernel.C due to
all the indirections, and was wondering if there was some form of docs
one could use as a reference.

Consider the arm pl011 uart driver, for example; it has a broad overview
of the registers and their functionality specific to that particular
piece of IP. Are there similar documents for fsi/scom/xscom/etc for the
power9 chips? I already have register documents 1-3 for the p9 but they
strike me as too broad, covering almost every thing in what seem to be
very ... unspecific(?) ways. Something like 'to initialize the fsi bus,
write 0xdeadbeef to register 0xdeadcode; to read something write this to
there' and so on.

Thanks,
Marty