Phoronix, the Linux-focused hardware website, highlighted patches for the GNU Compiler Collection (GCC) that implement HSA. This will allow newer APUs, such as AMD's Carrizo, to accelerate chunks of code (mostly loops) that have been tagged with a precompiler flag as valuable to be done on the GPU. While I have done some GPGPU development, many of the low-level specifics of HSA aren't areas that I have too much experience with.
The patches have been managed by Martin Jambor of SUSE Labs. You can see a slideshow presentation of their work on the GNU website. Even though features froze about a month ago, they are apparently hoping that this will make it into the official GCC 6 release. If so, many developers around the world will be able to target HSA-compatible hardware in the first half of 2016. Technically, anyone can do so regardless, but they would need to specifically use the unofficial branch on the GCC Subversion repository. This probably means compiling it themselves, and it might even be behind on a few features in other branches that were accepted into GCC 6.