1To understand all the Linux-USB framework, you'll use these resources: 2 3 * This source code. This is necessarily an evolving work, and 4 includes kerneldoc that should help you get a current overview. 5 ("make pdfdocs", and then look at "usb.pdf" for host side and 6 "gadget.pdf" for peripheral side.) Also, Documentation/usb has 7 more information. 8 9 * The USB 2.0 specification (from www.usb.org), with supplements 10 such as those for USB OTG and the various device classes. 11 The USB specification has a good overview chapter, and USB 12 peripherals conform to the widely known "Chapter 9". 13 14 * Chip specifications for USB controllers. Examples include 15 host controllers (on PCs, servers, and more); peripheral 16 controllers (in devices with Linux firmware, like printers or 17 cell phones); and hard-wired peripherals like Ethernet adapters. 18 19 * Specifications for other protocols implemented by USB peripheral 20 functions. Some are vendor-specific; others are vendor-neutral 21 but just standardized outside of the www.usb.org team. 22 23Here is a list of what each subdirectory here is, and what is contained in 24them. 25 26core/ - This is for the core USB host code, including the 27 usbfs files and the hub class driver ("khubd"). 28 29host/ - This is for USB host controller drivers. This 30 includes UHCI, OHCI, EHCI, and others that might 31 be used with more specialized "embedded" systems. 32 33gadget/ - This is for USB peripheral controller drivers and 34 the various gadget drivers which talk to them. 35 36 37Individual USB driver directories. A new driver should be added to the 38first subdirectory in the list below that it fits into. 39 40image/ - This is for still image drivers, like scanners or 41 digital cameras. 42../input/ - This is for any driver that uses the input subsystem, 43 like keyboard, mice, touchscreens, tablets, etc. 44../media/ - This is for multimedia drivers, like video cameras, 45 radios, and any other drivers that talk to the v4l 46 subsystem. 47../net/ - This is for network drivers. 48serial/ - This is for USB to serial drivers. 49storage/ - This is for USB mass-storage drivers. 50class/ - This is for all USB device drivers that do not fit 51 into any of the above categories, and work for a range 52 of USB Class specified devices. 53misc/ - This is for all USB device drivers that do not fit 54 into any of the above categories. 55