Documentation/usb/*, see the following:
Linux-USB project: http://www.linux-usb.org
- mirrors at http://www.suse.cz/development/linux-usb/
- and http://usb.in.tum.de/linux-usb/
+ mirrors at http://usb.in.tum.de/linux-usb/
and http://it.linux-usb.org
Linux USB Guide: http://linux-usb.sourceforge.net
Linux-USB device overview (working devices and drivers):