ubuntu usb drivers to run bfgminer
Are you running the miner as root? Do the devices show up when you run lsusb ?

In my experience, your user doesn't have access to the buses to talk to the devices, but putting sudo at the start (running as root) let me see and talk to my devices.

(I'm using cgminer compiled from source for LTC mining rather than BTC, but the principle should be the same.)