Rob Clark has been the one working on reverse-engineering the Qualcomm driver to create Freedreno. The driver is less than one year old but already there's the Gallium3D driver that's working well on Snapdragon S3 hardware and it soon may enter mainline Mesa.
Rob has basic 3D working for this driver and then through his X.Org driver he also has EXA/2D in place. Right now he's relying upon Qualcomm's open-source kernel driver, but in the end he may end up creating his own kernel driver too so it would be a complete custom driver stack.
Below is the video recording with Rob Clark talking about the Freedreno project during FOSDEM 2013.