AMD's Alex Deucher announced today via his personal blog that programming guides and register specifications on the 3D engines for the Evergreen, Northern Islands, Southern Islands, and Sea Islands GPUs is now in the NDA-free public domain. These parts represent the 3D engines on the Radeon HD 5000 through Radeon HD 8000 series graphics processors.
It's great to see AMD's public documentation finally catch up with their latest code. The Radeon HD 5000 "Evergreen" and Radeon HD 6000 "Northern Islands" open-source driver support is in good shape while the Southern Islands and Sea Islands open-source driver support is still very much a work-in-progress via the new RadeonSI Gallium3D driver, as has been covered by numerous Phoronix articles up to this point.
As was already noted, AMD has also released new HDA GPU audio programming details too.