There is a package for OpenCL 1.2 manual pages in the Ubuntu repository. To install the opencl-1.2-man-doc package, please run this command:

$ sudo apt-get install opencl-1.2-man-doc

After installing this package, we can check the OpenCL API with man command. For example, run man 3 clGetPlatformIDs to read the document for clGetPlatformIDs().