[Nouveau] [RFC] NVIDIA hardware reference headers

[Ken Adams]

Hello,

The Tegra GPU system software team has begun to align our new-chip
development efforts with Nouveau.  In particular we would like to arrive
at a place where the Nouveau kernel driver code base is our primary
development environment.

To that end I'd like to add some "official" hardware reference headers to
Nouveau.  The headers are derived from the information we use internally.
I have arranged the definitions such that the similarities and differences
between GPUs is made explicit.  I am happy to explain the rationale for
any design choices and since I wrote the generator I am able to tweak them
in almost any way the community prefers.

For this specific phase I can provide information already available for
GK20A and GM20B (via either nvgpu and/or the ongoing work to add Tegra
support to Nouveau).  We have already gone through an internal IP review
process on those... but, over the long-term I'm confident any information
we need to fill-in functionality >= NV50/G80 will be made public
eventually.
We just need to go through the internal steps necessary to make that
happen.

I started a Nouveau branch of my own to treat as a scratch pad and for
keeping track of discussion:
    https://github.com/kfractal/nouveau/tree/hwref

That branch tracks:
    https://github.com/Gnurou/nouveau/tree/staging

I also have:
  https://github.com/kfractal/nouveau/tree/old-hwref

 which has some earlier notes and discussion on use-patterns.

Once we're happy with the placement and organization of these headers and
accessors, I've been given the freedom (i.e. time and space) to follow
through and help make Nouveau our go-to chip development kernel driver.

I'm looking forward to comments and to actually, finally, jumping in :)

Thanks!
---
Ken Adams
kadams at nvidia.com