'\" t
.\"     Title: struct usb_configuration
.\"    Author: 
.\" Generator: DocBook XSL Stylesheets v1.78.1 <http://docbook.sf.net/>
.\"      Date: May 2018
.\"    Manual: Kernel Mode Gadget API
.\"    Source: Kernel Hackers Manual 3.16.56
.\"  Language: English
.\"
.TH "STRUCT USB_CONFIGURA" "9" "May 2018" "Kernel Hackers Manual 3\&.16\&" "Kernel Mode Gadget API"
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.SH "NAME"
struct_usb_configuration \- represents one gadget configuration
.SH "SYNOPSIS"
.sp
.nf
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;
};  
.fi
.SH "MEMBERS"
.PP
label
.RS 4
For diagnostics, describes the configuration\&.
.RE
.PP
strings
.RS 4
Tables of strings, keyed by identifiers assigned during @\fBbind\fR
and by language IDs provided in control requests\&.
.RE
.PP
descriptors
.RS 4
Table of descriptors preceding all function descriptors\&. Examples include OTG and vendor\-specific descriptors\&.
.RE
.PP
unbind
.RS 4
Reverses
\fIbind\fR; called as a side effect of unregistering the driver which added this configuration\&.
.RE
.PP
setup
.RS 4
Used to delegate control requests that aren\*(Aqt handled by standard device infrastructure or directed at a specific interface\&.
.RE
.PP
bConfigurationValue
.RS 4
Copied into configuration descriptor\&.
.RE
.PP
iConfiguration
.RS 4
Copied into configuration descriptor\&.
.RE
.PP
bmAttributes
.RS 4
Copied into configuration descriptor\&.
.RE
.PP
MaxPower
.RS 4
Power consumtion in mA\&. Used to compute bMaxPower in the configuration descriptor after considering the bus speed\&.
.RE
.PP
cdev
.RS 4
assigned by @\fBusb_add_config\fR
before calling @\fBbind\fR; this is the device associated with this configuration\&.
.RE
.SH "DESCRIPTION"
.PP
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\&.
.PP
Composite devices are, by definition, ones with configurations which include more than one function\&.
.PP
The lifecycle of a usb_configuration includes allocation, initialization of the fields described above, and calling @\fBusb_add_config\fR
to set up internal data and bind it to a specific device\&. The configuration\*(Aqs @\fBbind\fR
method is then used to initialize all the functions and then call @\fBusb_add_function\fR
for them\&.
.PP
Those functions would normally be independent of each other, but that\*(Aqs 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
\fBbind\fR
routine\&.
.SH "AUTHOR"
.PP
\fBDavid Brownell\fR <\&dbrownell@users.sourceforge.net\&>
.RS 4
Author.
.RE
.SH "COPYRIGHT"
.br