STRUCT USB_INTERFACE(9)           Host-Side Data Types and Macro          STRUCT USB_INTERFACE(9)



NAME
       struct_usb_interface - what usb device drivers talk to

SYNOPSIS
       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;
       };

MEMBERS
       altsetting
           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.

       cur_altsetting
           the current altsetting.

       num_altsetting
           number of altsettings defined.

       intf_assoc
           interface association descriptor

       minor
           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 probe function of the
           driver, after it has been assigned a minor number from the USB core by calling
           usb_register_dev.

       condition
           binding state of the interface: not bound, binding (in probe), bound to a driver, or
           unbinding (in disconnect)

       sysfs_files_created
           sysfs attributes exist

       ep_devs_created
           endpoint child pseudo-devices exist

       unregistering
           flag set when the interface is being unregistered

       needs_remote_wakeup
           flag set when the driver requires remote-wakeup capability during autosuspend.

       needs_altsetting0
           flag set when a set-interface request for altsetting 0 has been deferred.

       needs_binding
           flag set when the driver should be re-probed or unbound following a reset or suspend
           operation it doesn't support.

       resetting_device
           USB core reset the device, so use alt setting 0 as current; needs bandwidth alloc
           after reset.

       authorized
           This allows to (de)authorize individual interfaces instead a whole device in contrast
           to the device authorization.

       dev
           driver model's view of this device

       usb_dev
           if an interface is bound to the USB major, this will point to the sysfs representation
           for that device.

       pm_usage_cnt
           PM usage counter for this interface

       reset_ws
           Used for scheduling resets from atomic context.

DESCRIPTION
       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.

       The driver that is bound to the interface can use standard driver model calls such as
       dev_get_drvdata on the dev member of this structure.

       Each interface may have alternate settings. The initial configuration of a device sets
       altsetting 0, but the device driver can change that setting using usb_set_interface.
       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.

       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't necessarily stored in numerical order anyhow. Use
       usb_altnum_to_altsetting to look up an alternate setting in the altsetting array based on
       its number.

COPYRIGHT
Kernel Hackers Manual 4.8.                 January 2017                   STRUCT USB_INTERFACE(9)