Currently the AMD 7000 series APU (Kaveri) product line is still the only commercially available HSA enabled hardware platform. Please consult this link for specific information: HSA Platforms & Installation · HSAFoundation/HSA-Docs-AMD Wiki · GitHub
The next generation of HSA enabled chips will have programming interfaces conforming to the specifications available on the HSA Foundation web site at Standards - HSA Foundation. The specifications regarding HSA are subject to change, so the compatibility of a device with previous software development depends on the version of these specifications it supports.