'\" t
.\"     Title: struct usb_interface
.\"    Author: [FIXME: author] [see http://docbook.sf.net/el/author]
.\" Generator: DocBook XSL Stylesheets v1.78.1 <http://docbook.sf.net/>
.\"      Date: January 2017
.\"    Manual: Host-Side Data Types and Macros
.\"    Source: Kernel Hackers Manual 4.8.15
.\"  Language: English
.\"
.TH "STRUCT USB_INTERFACE" "9" "January 2017" "Kernel Hackers Manual 4\&.8\&." "Host-Side Data Types and Macro"
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.SH "NAME"
struct_usb_interface \- what usb device drivers talk to
.SH "SYNOPSIS"
.sp
.nf
struct usb_interface {
  struct usb_host_interface * altsetting;
  struct usb_host_interface * cur_altsetting;
  unsigned num_altsetting;
  struct usb_interface_assoc_descriptor * intf_assoc;
  int minor;
  enum usb_interface_condition condition;
  unsigned sysfs_files_created:1;
  unsigned ep_devs_created:1;
  unsigned unregistering:1;
  unsigned needs_remote_wakeup:1;
  unsigned needs_altsetting0:1;
  unsigned needs_binding:1;
  unsigned resetting_device:1;
  unsigned authorized:1;
  struct device dev;
  struct device * usb_dev;
  atomic_t pm_usage_cnt;
  struct work_struct reset_ws;
};  
.fi
.SH "MEMBERS"
.PP
altsetting
.RS 4
array of interface structures, one for each alternate setting that may be selected\&. Each one includes a set of endpoint configurations\&. They will be in no particular order\&.
.RE
.PP
cur_altsetting
.RS 4
the current altsetting\&.
.RE
.PP
num_altsetting
.RS 4
number of altsettings defined\&.
.RE
.PP
intf_assoc
.RS 4
interface association descriptor
.RE
.PP
minor
.RS 4
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\&.
.RE
.PP
condition
.RS 4
binding state of the interface: not bound, binding (in
\fBprobe\fR), bound to a driver, or unbinding (in
\fBdisconnect\fR)
.RE
.PP
sysfs_files_created
.RS 4
sysfs attributes exist
.RE
.PP
ep_devs_created
.RS 4
endpoint child pseudo\-devices exist
.RE
.PP
unregistering
.RS 4
flag set when the interface is being unregistered
.RE
.PP
needs_remote_wakeup
.RS 4
flag set when the driver requires remote\-wakeup capability during autosuspend\&.
.RE
.PP
needs_altsetting0
.RS 4
flag set when a set\-interface request for altsetting 0 has been deferred\&.
.RE
.PP
needs_binding
.RS 4
flag set when the driver should be re\-probed or unbound following a reset or suspend operation it doesn\*(Aqt support\&.
.RE
.PP
resetting_device
.RS 4
USB core reset the device, so use alt setting 0 as current; needs bandwidth alloc after reset\&.
.RE
.PP
authorized
.RS 4
This allows to (de)authorize individual interfaces instead a whole device in contrast to the device authorization\&.
.RE
.PP
dev
.RS 4
driver model\*(Aqs view of this device
.RE
.PP
usb_dev
.RS 4
if an interface is bound to the USB major, this will point to the sysfs representation for that device\&.
.RE
.PP
pm_usage_cnt
.RS 4
PM usage counter for this interface
.RE
.PP
reset_ws
.RS 4
Used for scheduling resets from atomic context\&.
.RE
.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\*(Aqs endpoints can be defined in a usb
\(lqclass\(rq
specification, or by a product\*(Aqs vendor\&. The (default) control endpoint is part of every interface, but is never listed among the interface\*(Aqs 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 altsetting 0, but the device driver can change that setting using
\fBusb_set_interface\fR\&. Alternate settings are often used to control 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\&.
.PP
The USB specification says that alternate setting numbers must run from 0 to one less than the total number of alternate settings\&. But some devices manage to mess this up, and the structures aren\*(Aqt necessarily stored in numerical order anyhow\&. Use
\fBusb_altnum_to_altsetting\fR
to look up an alternate setting in the altsetting array based on its number\&.
.SH "COPYRIGHT"
.br