1 .\" Copyright (c) 1997, 1998
2 .\" Nick Hibma <n_hibma@FreeBSD.org>. All rights reserved.
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28 .\" $FreeBSD: src/share/man/man4/usb.4,v 1.32 2005/04/20 07:33:09 simon Exp $
29 .\" $DragonFly: src/share/man/man4/usb.4,v 1.5 2006/12/10 02:16:26 sephe Exp $
36 .Nd Universal Serial Bus
44 provides machine-independent bus support and drivers for
50 driver has three layers: the controller, the bus, and the
52 The controller attaches to a physical bus
57 bus attaches to the controller, and the root hub attaches
59 Any devices attached to the bus will attach to the root hub
60 or another hub attached to the
66 device will always be present as it is needed for the
68 .Sh INTRODUCTION TO USB
71 is a 12 Mb/s serial bus (1.5 Mb/s for low speed devices).
74 has a host controller that is the master of the bus;
75 all other devices on the bus only speak when spoken to.
77 There can be up to 127 devices (apart from the host controller)
78 on a bus, each with its own address.
79 The addresses are assigned
80 dynamically by the host when each device is attached to the bus.
82 Within each device there can be up to 16 endpoints.
84 is individually addressed and the addresses are static.
85 Each of these endpoints will communicate in one of four different modes:
86 .Em control , isochronous , bulk ,
89 A device always has at least one endpoint.
90 This endpoint has address 0 and is a control
91 endpoint and is used to give commands to and extract basic data,
92 such as descriptors, from the device.
93 Each endpoint, except the control endpoint, is unidirectional.
95 The endpoints in a device are grouped into interfaces.
96 An interface is a logical unit within a device; e.g.\&
97 a compound device with both a keyboard and a trackball would present
98 one interface for each.
99 An interface can sometimes be set into different modes,
100 called alternate settings, which affects how it operates.
101 Different alternate settings can have different endpoints
104 A device may operate in different configurations.
106 configuration, the device may present different sets of endpoints
109 .\"Each device located on a hub has several
112 .\".Bl -tag -compact -width xxxxxx
114 .\"this is the number of the port on the closest upstream hub.
115 .\".It Cd configuration
116 .\"this is the configuration the device must be in for this driver to attach.
117 .\"This locator does not set the configuration; it is iterated by the bus
120 .\"this is the interface number within a device that an interface driver
123 .\"this is the 16 bit vendor id of the device.
125 .\"this is the 16 bit product id of the device.
127 .\"this is the 16 bit release (revision) number of the device.
129 .\"The first locator can be used to pin down a particular device
130 .\"according to its physical position in the device tree.
131 .\"The last three locators can be used to pin down a particular
132 .\"device according to what device it actually is.
134 The bus enumeration of the
136 bus proceeds in several steps:
139 Any device specific driver can attach to the device.
141 If none is found, any device class specific driver can attach.
143 If none is found, all configurations are iterated over.
144 For each configuration, all the interfaces are iterated over, and interface
146 If any interface driver attached in a certain
147 configuration, the iteration over configurations is stopped.
149 If still no drivers have been found, the generic
153 .Sh USB CONTROLLER INTERFACE
154 Use the following to get access to the
156 specific structures and defines.
162 can be opened and a few operations can be performed on it.
165 system call will say that I/O is possible on the controller device when a
167 device has been connected or disconnected to the bus.
171 commands are supported on the controller device:
172 .Bl -tag -width xxxxxx
174 This command will cause a complete bus discovery to be initiated.
175 If any devices attached or detached from the bus they will be
176 processed during this command.
177 This is the only way that new devices are found on the bus.
178 .It Dv USB_DEVICEINFO Vt "struct usb_device_info"
179 This command can be used to retrieve some information about a device
183 field should be filled before the call and the other fields will
184 be filled by information about the device on that address.
185 Should no such device exist, an error is reported.
187 #define USB_MAX_DEVNAMES 4
188 #define USB_MAX_DEVNAMELEN 16
189 struct usb_device_info {
191 u_int8_t udi_addr; /* device address */
192 usb_event_cookie_t udi_cookie;
193 char udi_product[USB_MAX_STRING_LEN];
194 char udi_vendor[USB_MAX_STRING_LEN];
196 u_int16_t udi_productNo;
197 u_int16_t udi_vendorNo;
198 u_int16_t udi_releaseNo;
200 u_int8_t udi_subclass;
201 u_int8_t udi_protocol;
204 #define USB_SPEED_LOW 1
205 #define USB_SPEED_FULL 2
206 #define USB_SPEED_HIGH 3
207 int udi_power; /* power consumption in mA, 0 if selfpowered */
209 char udi_devnames[USB_MAX_DEVNAMES][USB_MAX_DEVNAMELEN];
210 u_int8_t udi_ports[16];/* hub only: addresses of devices on ports */
211 #define USB_PORT_ENABLED 0xff
212 #define USB_PORT_SUSPENDED 0xfe
213 #define USB_PORT_POWERED 0xfd
214 #define USB_PORT_DISABLED 0xfc
221 contain the topological information for the device.
223 contains the device names of the connected drivers.
227 Zip drive connected will be
230 .Va udi_product , udi_vendor
233 fields contain self-explanatory descriptions of the device.
234 .Va udi_productNo , udi_vendorNo , udi_releaseNo , udi_class , udi_subclass
237 contain the corresponding values from the device descriptors.
240 field shows the current configuration of the device.
243 indicates whether the device is at low speed
244 .Pq Dv USB_SPEED_LOW ,
246 .Pq Dv USB_SPEED_FULL
248 .Pq Dv USB_SPEED_HIGH .
251 field shows the power consumption in milli-amps drawn at 5 volts,
252 or zero if the device is self powered.
254 If the device is a hub, the
256 field is non-zero, and the
258 field contains the addresses of the connected devices.
259 If no device is connected to a port, one of the
261 values indicates its status.
262 .It Dv USB_DEVICESTATS Vt "struct usb_device_stats"
263 This command retrieves statistics about the controller.
265 struct usb_device_stats {
266 u_long uds_requests[4];
272 field is indexed by the transfer kind, i.e.\&
274 and indicates how many transfers of each kind that has been completed
276 .It Dv USB_REQUEST Vt "struct usb_ctl_request"
277 This command can be used to execute arbitrary requests on the control pipe.
280 and should be used with great care since it
281 can destroy the bus integrity.
286 contains definitions for the types used by the various
289 The naming convention of the fields for the various
291 descriptors exactly follows the naming in the
294 Byte sized fields can be accessed directly, but word (16 bit)
295 sized fields must be access by the
298 .Fn USETW field value
299 macros to handle byte order and alignment properly.
303 similarly contains the definitions for
304 Human Interface Devices
306 .Sh USB EVENT INTERFACE
309 events are reported via the
312 This devices can be opened for reading and each
314 will yield an event record (if something has happened).
317 system call can be used to determine if an event record is available
320 The event record has the following definition:
324 #define USB_EVENT_CTRLR_ATTACH 1
325 #define USB_EVENT_CTRLR_DETACH 2
326 #define USB_EVENT_DEVICE_ATTACH 3
327 #define USB_EVENT_DEVICE_DETACH 4
328 #define USB_EVENT_DRIVER_ATTACH 5
329 #define USB_EVENT_DRIVER_DETACH 6
330 struct timespec ue_time;
335 struct usb_device_info ue_device;
337 usb_event_cookie_t ue_cookie;
345 field identifies the type of event that is described.
346 The possible events are attach/detach of a host controller,
347 a device, or a device driver.
348 The union contains information
349 pertinent to the different types of events.
351 .Fn USB_EVENT_IS_ATTACH "ue_type"
353 .Fn USB_EVENT_IS_DETACH "ue_type"
354 can be used to determine if an event was an
362 contains the number of the
364 bus for host controller events.
368 record contains information about the device in a device event event.
372 is an opaque value that uniquely determines which
373 device a device driver has been attached to (i.e., it equals
374 the cookie value in the device that the driver attached to).
378 contains the name of the device (driver) as seen in, e.g.,
381 Note that there is a separation between device and device
383 A device event is generated when a physical
385 device is attached or detached.
389 have zero, one, or many device drivers associated with it.
393 specifications can be found at:
395 .D1 Pa http://www.usb.org/developers/docs/
422 driver first appeared in
427 driver was written by
428 .An Lennart Augustsson Aq augustss@carlstedt.se