1STRUCT USB_INTERFACE(9) Host-Side Data Types and Macro STRUCT USB_INTERFACE(9)
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NAME

6       struct_usb_interface - what usb device drivers talk to
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SYNOPSIS

9       struct usb_interface {
10         struct usb_host_interface * altsetting;
11         struct usb_host_interface * cur_altsetting;
12         unsigned num_altsetting;
13         struct usb_interface_assoc_descriptor * intf_assoc;
14         int minor;
15         enum usb_interface_condition condition;
16         unsigned sysfs_files_created:1;
17         unsigned ep_devs_created:1;
18         unsigned unregistering:1;
19         unsigned needs_remote_wakeup:1;
20         unsigned needs_altsetting0:1;
21         unsigned needs_binding:1;
22         unsigned resetting_device:1;
23         unsigned authorized:1;
24         struct device dev;
25         struct device * usb_dev;
26         atomic_t pm_usage_cnt;
27         struct work_struct reset_ws;
28       };
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MEMBERS

31       altsetting
32           array of interface structures, one for each alternate setting that
33           may be selected. Each one includes a set of endpoint
34           configurations. They will be in no particular order.
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36       cur_altsetting
37           the current altsetting.
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39       num_altsetting
40           number of altsettings defined.
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42       intf_assoc
43           interface association descriptor
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45       minor
46           the minor number assigned to this interface, if this interface is
47           bound to a driver that uses the USB major number. If this interface
48           does not use the USB major, this field should be unused. The driver
49           should set this value in the probe function of the driver, after it
50           has been assigned a minor number from the USB core by calling
51           usb_register_dev.
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53       condition
54           binding state of the interface: not bound, binding (in probe),
55           bound to a driver, or unbinding (in disconnect)
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57       sysfs_files_created
58           sysfs attributes exist
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60       ep_devs_created
61           endpoint child pseudo-devices exist
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63       unregistering
64           flag set when the interface is being unregistered
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66       needs_remote_wakeup
67           flag set when the driver requires remote-wakeup capability during
68           autosuspend.
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70       needs_altsetting0
71           flag set when a set-interface request for altsetting 0 has been
72           deferred.
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74       needs_binding
75           flag set when the driver should be re-probed or unbound following a
76           reset or suspend operation it doesn't support.
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78       resetting_device
79           USB core reset the device, so use alt setting 0 as current; needs
80           bandwidth alloc after reset.
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82       authorized
83           This allows to (de)authorize individual interfaces instead a whole
84           device in contrast to the device authorization.
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86       dev
87           driver model's view of this device
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89       usb_dev
90           if an interface is bound to the USB major, this will point to the
91           sysfs representation for that device.
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93       pm_usage_cnt
94           PM usage counter for this interface
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96       reset_ws
97           Used for scheduling resets from atomic context.
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DESCRIPTION

100       USB device drivers attach to interfaces on a physical device. Each
101       interface encapsulates a single high level function, such as feeding an
102       audio stream to a speaker or reporting a change in a volume control.
103       Many USB devices only have one interface. The protocol used to talk to
104       an interface's endpoints can be defined in a usb “class” specification,
105       or by a product's vendor. The (default) control endpoint is part of
106       every interface, but is never listed among the interface's descriptors.
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108       The driver that is bound to the interface can use standard driver model
109       calls such as dev_get_drvdata on the dev member of this structure.
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111       Each interface may have alternate settings. The initial configuration
112       of a device sets altsetting 0, but the device driver can change that
113       setting using usb_set_interface. Alternate settings are often used to
114       control the use of periodic endpoints, such as by having different
115       endpoints use different amounts of reserved USB bandwidth. All
116       standards-conformant USB devices that use isochronous endpoints will
117       use them in non-default settings.
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119       The USB specification says that alternate setting numbers must run from
120       0 to one less than the total number of alternate settings. But some
121       devices manage to mess this up, and the structures aren't necessarily
122       stored in numerical order anyhow. Use usb_altnum_to_altsetting to look
123       up an alternate setting in the altsetting array based on its number.
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126Kernel Hackers Manual 3.10         June 2019           STRUCT USB_INTERFACE(9)
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