at76_usb driver supports USB devices using Atmel at76c50x chipsets. Only 802.11b protocol is supported. The driver has it's own 802.11 stack.
See also at76c50x-usb, the mac80211 port of this driver.
The driver is now in staging tree and was included in linux 2.6.28 release. The driver is now in maintenance mode and all development should happen with at76c50x-usb.
The original at76_usb git tree was here:
But it seems to be gone now. The current mac80211 port is in linux-testing and the history for the driver is here:
Some Atmel wireless cards require firmware to be loaded. The firmware can be downloaded from this site: