Hi. The above link at Lattice is not broken - just tested it and you have to log in with your account before you will have access to the posted fileset. After logging in, I am able to download a fileset of size 206kb. Please try again.
I tried again with the same account and it works today. Seems like it took some time for my account to gett fully unlocked.
The firmware works fine, as far as i can test, it enumarates as it should. But i cant adapt it in any way, because there is only the precompiled image, but no way to (for example) reconfigure the GPIF.
So i'm guessing the firmware is not public and usable as a reference design?
For firmware source, please contact Lattice Semi.