STRUCT USB_INTERFACE(9) Host-Side Data Types and Macro STRUCT USB_INTERFACE(9)NAMEstruct_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 is_active:1;
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 reset_running: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)
is_active
flag set when the interface is bound and not suspended.
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.
reset_running
set to 1 if the interface is currently running a queued reset so
that usb_cancel_queued_reset doesn´t try to remove from the
workqueue when running inside the worker thread. See
__usb_queue_reset_device.
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; autosuspend is not allowed
unless the counter is 0.
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.
COPYRIGHTKernel Hackers Manual 2.6. November 2013 STRUCT USB_INTERFACE(9)
