Have spent a lot of time on this one one but can't find an answer here.
Ubuntu 14.10 clean install. AMD A10-7700K APU with Radeon(TM) R7 Graphics x4.
1) Started with the xserver open-source wrapper and all seemed ok.
2) Installed BOINC but 'No useable GPUs found' in Event Log.
3) Reinstalled BOINC with boinc-amd-opencl but same result, except that it installed AMD graphics fglrx-updates.
4) Downloaded & installed latest Calalyst from AMD and that didn't work at all, wouldn't boot past the mauve screen!
5) Reverted back to setup above. But still no OpenCL for BOINC.
6) In case this was only a 'BOINC' glitch, I went to their website. Found some old stuff about KAVERI support, which didn't solve it.
7) Another program with this problem, darktable, also can't find OpenCL.
A snag is that there doesn't seem to a utility in Ubuntu that tells me clearly whether OpenCL is functional or not.
So conclusion? Ubuntu 14.10 + fglrx 14.201 + AMD A10-7700K = no OpenCL.
True? Hopefully someone out there knows the answer.
Ubuntu dropped support for the old fglrx drivers in 14.04.04 recent patches (they USED to work but Ubuntu changed something that BROKE the support, so you pretty much have to stick with 14.04.03 or earlier).
AMD has NEVER offered any "official" support for OpenCL on the A10 series in their ROCm or AMDGPU-PRO series drivers that DO work with more recent Ubuntu versions, and it appears they plan to NEVER DO SO even though they DO support discrete GPUs that are OLDER than many of the A10 series APUs.
The ROCm stack will SOMETIMES work with the GCN-based A10 APUs (A10-6xxx I think, and definitely the A10-7xxx and later), but that's very hit-or-miss on if it will work or not on a given installation - and is NOT officially supported, so forget getting any SUPPORT out of AMD on such a setup.
Also, if you are going to use fglrx at all, it would be better to use the final release version 14.302 instead of the older .201 version Corresponds to AMD driver version 15.12 (.201 I believe was 15.07 or so).