Some more changes I still had in my pipe (and for which I never filed a pull request, as they were based on other changes which had not been merged back then):
Get the driver to build on Ubuntu 14.10 (-fPIC flag)
Use platform’s hidapi library
Fail with error if hid_open() fails
Print an error message if device can’t be opened (e.g. hid_open() failed or no device found)
dev rules so the Si470x can be accessed by non-root users
Replace a goto (which can easily be replaced here)
Some more changes I still had in my pipe (and for which I never filed a pull request, as they were based on other changes which had not been merged back then):
-fPICflag)hid_open()failshid_open()failed or no device found)goto(which can easily be replaced here)