Former Intel employee Eric Anholt shared with the Mesa developers that he plans to start adding his VC4 Gallium3D driver to the mainline Mesa tree. The driver is running in good shape on the x86-based Raspberry Pi simulator while on real hardware it should be in fairly good shape.
There's also the VC4 DRM driver for the Linux kernel that Eric Anholt has also been designing, but that kernel code isn't yet ready for Linux 3.17.
The VC4 Gallium3D driver code should start hitting mainline Mesa in time for the Mesa 10.3 release. The VC4 driver is the second ARM Gallium3D driver after Freedreno.