STRUCT USB_CONFIGURA(9) Kernel Mode Gadget API STRUCT USB_CONFIGURA(9)NAMEstruct_usb_configuration - represents one gadget configuration
SYNOPSIS
struct usb_configuration {
const char * label;
struct usb_gadget_strings ** strings;
const struct usb_descriptor_header ** descriptors;
int (* bind) (struct usb_configuration *);
void (* unbind) (struct usb_configuration *);
int (* setup) (struct usb_configuration *,const struct usb_ctrlrequest *);
u8 bConfigurationValue;
u8 iConfiguration;
u8 bmAttributes;
u8 bMaxPower;
struct usb_composite_dev * cdev;
};
MEMBERS
label
For diagnostics, describes the configuration.
strings
Tables of strings, keyed by identifiers assigned during bind() and
by language IDs provided in control requests.
descriptors
Table of descriptors preceding all function descriptors. Examples
include OTG and vendor-specific descriptors.
bind
Called from usb_add_config() to allocate resources unique to this
configuration and to call usb_add_function() for each function
used.
unbind
Reverses bind; called as a side effect of unregistering the driver
which added this configuration.
setup
Used to delegate control requests that aren´t handled by standard
device infrastructure or directed at a specific interface.
bConfigurationValue
Copied into configuration descriptor.
iConfiguration
Copied into configuration descriptor.
bmAttributes
Copied into configuration descriptor.
bMaxPower
Copied into configuration descriptor.
cdev
assigned by usb_add_config() before calling bind(); this is the
device associated with this configuration.
DESCRIPTION
Configurations are building blocks for gadget drivers structured around
function drivers. Simple USB gadgets require only one function and one
configuration, and handle dual-speed hardware by always providing the
same functionality. Slightly more complex gadgets may have more than
one single-function configuration at a given speed; or have
configurations that only work at one speed.
Composite devices are, by definition, ones with configurations which
include more than one function.
The lifecycle of a usb_configuration includes allocation,
initialization of the fields described above, and calling
usb_add_config() to set up internal data and bind it to a specific
device. The configuration´s bind() method is then used to initialize
all the functions and then call usb_add_function() for them.
Those functions would normally be independant of each other, but that´s
not mandatory. CDC WMC devices are an example where functions often
depend on other functions, with some functions subsidiary to others.
Such interdependency may be managed in any way, so long as all of the
descriptors complete by the time the composite driver returns from its
bind routine.
AUTHOR
David Brownell <dbrownell@users.sourceforge.net>
Author.
COPYRIGHTKernel Hackers Manual 2.6. November 2013 STRUCT USB_CONFIGURA(9)
