After recently getting some older Radeon GPUs to OpenGL 4.2 with new R600g patches and making other improvements to R600g, David Airlie has now sent out a set of patches for getting compute shaders and GLSL 4.30 working for some older pre-GCN GPUs with the R600 Gallium3D driver…
Source: Phoronix – Compute Shader & GLSL 4.30 Support For R600 Gallium3D