.\" This documentation was generated from the book titled "The Linux-USB Host Side API", which is part of the Linux kernel source.
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.TH "USB_INTERFACE" "9" "07 August 2003" "" ""

.SH NAME
struct usb_interface \- what usb device drivers talk to
.SH SYNOPSIS

.nf
struct usb_interface {
  /* array of alternate settings for this interface.* these will be in numeric order, 0..num_altsettting*/struct usb_host_interface * altsetting;
  unsigned act_altsetting;
  unsigned num_altsetting;
  unsigned max_altsetting;
  struct usb_driver * driver;
  int minor;
  struct device dev;
  struct class_device class_dev;
};  
.fi
.SH "MEMBERS"
.TP
\fBaltsetting\fR
array of interface descriptors, one for each alternate
setting that may be selected.  Each one includes a set of
endpoint configurations and will be in numberic order,
0..num_altsetting.
.TP
\fBact_altsetting\fR
index of current altsetting.  this number is always
less than num_altsetting.  after the device is configured, each
interface uses its default setting of zero.
.TP
\fBnum_altsetting\fR
number of altsettings defined.
.TP
\fBmax_altsetting\fR
the max number of altsettings for this interface.
.TP
\fBdriver\fR
the USB driver that is bound to this interface.
.TP
\fBminor\fR
the minor number assigned to this interface, if this
interface is bound to a driver that uses the USB major number.
If this interface does not use the USB major, this field should
be unused.  The driver should set this value in the \fBprobe\fR
function of the driver, after it has been assigned a minor
number from the USB core by calling \fBusb_register_dev\fR.
.TP
\fBdev\fR
driver model's view of this device
.TP
\fBclass_dev\fR
driver model's class view of this device.
.SH "DESCRIPTION"
.PP
USB device drivers attach to interfaces on a physical device.  Each
interface encapsulates a single high level function, such as feeding
an audio stream to a speaker or reporting a change in a volume control.
Many USB devices only have one interface.  The protocol used to talk to
an interface's endpoints can be defined in a usb ``class'' specification,
or by a product's vendor.  The (default) control endpoint is part of
every interface, but is never listed among the interface's descriptors.
.PP
The driver that is bound to the interface can use standard driver model
calls such as \fBdev_get_drvdata\fR on the dev member of this structure.
.PP
Each interface may have alternate settings.  The initial configuration
of a device sets the first of these, but the device driver can change
that setting using \fBusb_set_interface\fR.  Alternate settings are often
used to control the the use of periodic endpoints, such as by having
different endpoints use different amounts of reserved USB bandwidth.
All standards-conformant USB devices that use isochronous endpoints
will use them in non-default settings.
.SH "ABOUT THIS DOCUMENT"
.PP
This documentation was generated with kernel version 2.6.0.