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Diffstat (limited to 'Documentation/usb/gadget_configfs.rst')
| -rw-r--r-- | Documentation/usb/gadget_configfs.rst | 45 |
1 files changed, 22 insertions, 23 deletions
diff --git a/Documentation/usb/gadget_configfs.rst b/Documentation/usb/gadget_configfs.rst index 868e118a2644..ada57c0e34aa 100644 --- a/Documentation/usb/gadget_configfs.rst +++ b/Documentation/usb/gadget_configfs.rst @@ -92,7 +92,7 @@ Then the strings can be specified:: Further custom string descriptors can be created as directories within the language's directory, with the string text being written to the "s" attribute -within the string's directory: +within the string's directory:: $ mkdir strings/0x409/xu.0 $ echo <string text> > strings/0x409/xu.0/s @@ -104,9 +104,9 @@ string descriptors to associate those strings with class descriptors. ------------------------------ Each gadget will consist of a number of configurations, their corresponding -directories must be created: +directories must be created:: -$ mkdir configs/<name>.<number> + $ mkdir configs/<name>.<number> where <name> can be any string which is legal in a filesystem and the <number> is the configuration's number, e.g.:: @@ -246,7 +246,7 @@ a symlink to a function being removed from the configuration, e.g.:: ... ... -Remove strings directories in configurations: +Remove strings directories in configurations:: $ rmdir configs/<config name>.<number>/strings/<lang> @@ -270,7 +270,7 @@ e.g.:: ... ... -Remove functions (function modules are not unloaded, though): +Remove functions (function modules are not unloaded, though):: $ rmdir functions/<name>.<instance name> @@ -369,18 +369,18 @@ For more information on configfs please see The concepts described above translate to USB gadgets like this: 1. A gadget has its config group, which has some attributes (idVendor, -idProduct etc) and default sub-groups (configs, functions, strings). -Writing to the attributes causes the information to be stored in -appropriate locations. In the configs, functions and strings sub-groups -a user can create their sub-groups to represent configurations, functions, -and groups of strings in a given language. + idProduct etc) and default sub-groups (configs, functions, strings). + Writing to the attributes causes the information to be stored in appropriate + locations. In the configs, functions and strings sub-groups a user can + create their sub-groups to represent configurations, functions, and groups + of strings in a given language. 2. The user creates configurations and functions, in the configurations -creates symbolic links to functions. This information is used when the -gadget's UDC attribute is written to, which means binding the gadget -to the UDC. The code in drivers/usb/gadget/configfs.c iterates over -all configurations, and in each configuration it iterates over all -functions and binds them. This way the whole gadget is bound. + creates symbolic links to functions. This information is used when the + gadget's UDC attribute is written to, which means binding the gadget to the + UDC. The code in drivers/usb/gadget/configfs.c iterates over all + configurations, and in each configuration it iterates over all functions and + binds them. This way the whole gadget is bound. 3. The file drivers/usb/gadget/configfs.c contains code for @@ -388,13 +388,12 @@ functions and binds them. This way the whole gadget is bound. - gadget's default groups (configs, functions, strings) - associating functions with configurations (symlinks) -4. Each USB function naturally has its own view of what it wants -configured, so config_groups for particular functions are defined -in the functions implementation files drivers/usb/gadget/f_*.c. +4. Each USB function naturally has its own view of what it wants configured, so + config_groups for particular functions are defined in the functions + implementation files drivers/usb/gadget/f_*.c. 5. Function's code is written in such a way that it uses - -usb_get_function_instance(), which, in turn, calls request_module. -So, provided that modprobe works, modules for particular functions -are loaded automatically. Please note that the converse is not true: -after a gadget is disabled and torn down, the modules remain loaded. + usb_get_function_instance(), which, in turn, calls request_module. So, + provided that modprobe works, modules for particular functions are loaded + automatically. Please note that the converse is not true: after a gadget is + disabled and torn down, the modules remain loaded. |