starting with Linux Kernel 4.18 the ROCm OpenCL driver works!
All you need are the following packages:
hsa-rocr-dev-1.1.8-15-ge851b7a-Linux.rpm hsakmt-roct-1.0.8-1-ge3dd067-Linux.rpm rocm-opencl-1.2.0-2018071635.x86_64.rpm rocm-opencl-devel-1.2.0-2018071635.x86_64.rpm
If you don’t have an RPM based system, you can also extract the files from the RPMs.
$ clinfo Number of platforms 1 Platform Name AMD Accelerated Parallel Processing Platform Vendor Advanced Micro Devices, Inc. Platform Version OpenCL 2.0 AMD-APP (2482.3)