Documentation/usb/gadget_configfs.rst

15 be connected to a USB Host to extend it with additional functions like a serial
20 functions, each function representing e.g. a serial connection or a SCSI disk.
22 Linux provides a number of functions for gadgets to use.
25 and which functions each configuration will provide.
100 Where function drivers support it, functions may allow symlinks to these custom
133 3. Creating the functions
136 The gadget will provide some functions, for each function its corresponding
139 	$ mkdir functions/<name>.<instance name>
144   $ mkdir functions/ncm.usb0 # usb_f_ncm.ko gets loaded with request_module()
155 4. Associating the functions with their configurations
159 configurations specified and a number of functions available. What remains
164 	$ ln -s functions/<name>.<instance name> configs/<name>.<number>
168 	$ ln -s functions/ncm.usb0 configs/c.1
178 configurations and functions.
190   ./configs/c.1/ncm.usb0 -> ../../../../usb_gadget/g1/functions/ncm.usb0
196   ./functions
197   ./functions/ncm.usb0
198   ./functions/ncm.usb0/ifname
199   ./functions/ncm.usb0/qmult
200   ./functions/ncm.usb0/host_addr
201   ./functions/ncm.usb0/dev_addr
236 Remove functions from configurations::
273 Remove functions (function modules are not unloaded, though):
275 	$ rmdir functions/<name>.<instance name>
279 	$ rmdir functions/ncm.usb0
341 two functions to decide what they actually do.
372 idProduct etc) and default sub-groups (configs, functions, strings).
374 appropriate locations. In the configs, functions and strings sub-groups
375 a user can create their sub-groups to represent configurations, functions,
378 2. The user creates configurations and functions, in the configurations
379 creates symbolic links to functions. This information is used when the
383 functions and binds them. This way the whole gadget is bound.
388 	- gadget's default groups (configs, functions, strings)
389 	- associating functions with configurations (symlinks)
392 configured, so config_groups for particular functions are defined
393 in the functions implementation files drivers/usb/gadget/f_*.c.
398 So, provided that modprobe works, modules for particular functions