| struct_usb_configuration(9) - phpMan
STRUCT USB_CONFIGURA(9) Kernel Mode Gadget API STRUCT USB_CONFIGURA(9)
NAME
struct_usb_configuration - represents one gadget configuration
SYNOPSIS
struct usb_configuration {
const char * label;
struct usb_gadget_strings ** strings;
const struct usb_descriptor_header ** descriptors;
void (* unbind) (struct usb_configuration *);
int (* setup) (struct usb_configuration *,const struct usb_ctrlrequest *);
u8 bConfigurationValue;
u8 iConfiguration;
u8 bmAttributes;
u16 MaxPower;
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.
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.
MaxPower
Power consumtion in mA. Used to compute bMaxPower in the configuration descriptor
after considering the bus speed.
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 independent 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 AT users.net>
Author.
COPYRIGHT
Kernel Hackers Manual 4.8. January 2017 STRUCT USB_CONFIGURA(9)
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