Add <linux/usb/composite.h> interfaces for composite gadget drivers, and
basic implementation support behind it:
- struct usb_function ... groups one or more interfaces into a function
managed as one unit within a configuration, to which it's added by
usb_add_function().
- struct usb_configuration ... groups one or more such functions into
a configuration managed as one unit by a driver, to which it's added
by usb_add_config(). These operate at either high or full/low speeds
and at a given bMaxPower.
- struct usb_composite_driver ... groups one or more such configurations
into a gadget driver, which may be registered or unregistered.
- struct usb_composite_dev ... a usb_composite_driver manages this; it
wraps the usb_gadget exposed by the controller driver.
This also includes some basic kerneldoc.
How to use it (the short version): provide a usb_composite_driver with a
bind() that calls usb_add_config() for each of the needed configurations.
The configurations in turn have bind() calls, which will usb_add_function()
for each function required. Each function's bind() allocates resources
needed to perform its tasks, like endpoints; sometimes configurations will
allocate resources too.
Separate patches will convert most gadget drivers to this infrastructure.
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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