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35 .Nd Universal Serial Bus
43 provides machine-independent bus support and drivers for
49 driver has three layers: the controller, the bus, and the
51 The controller attaches to a physical bus
56 bus attaches to the controller, and the root hub attaches
58 Any devices attached to the bus will attach to the root hub
59 or another hub attached to the
65 device will always be present as it is needed for the
67 .Sh INTRODUCTION TO USB
70 is a 12 Mb/s serial bus (1.5 Mb/s for low speed devices).
73 has a host controller that is the master of the bus;
74 all other devices on the bus only speak when spoken to.
76 There can be up to 127 devices (apart from the host controller)
77 on a bus, each with its own address.
78 The addresses are assigned
79 dynamically by the host when each device is attached to the bus.
81 Within each device there can be up to 16 endpoints.
83 is individually addressed and the addresses are static.
84 Each of these endpoints will communicate in one of four different modes:
85 .Em control , isochronous , bulk ,
88 A device always has at least one endpoint.
89 This endpoint has address 0 and is a control
90 endpoint and is used to give commands to and extract basic data,
91 such as descriptors, from the device.
92 Each endpoint, except the control endpoint, is unidirectional.
94 The endpoints in a device are grouped into interfaces.
95 An interface is a logical unit within a device; e.g.\&
96 a compound device with both a keyboard and a trackball would present
97 one interface for each.
98 An interface can sometimes be set into different modes,
99 called alternate settings, which affects how it operates.
100 Different alternate settings can have different endpoints
103 A device may operate in different configurations.
105 configuration, the device may present different sets of endpoints
108 .\" Each device located on a hub has several
111 .\" .Bl -tag -compact -width xxxxxx
113 .\" this is the number of the port on the closest upstream hub.
114 .\" .It Cd configuration
115 .\" this is the configuration the device must be in for this driver to attach.
116 .\" This locator does not set the configuration; it is iterated by the bus
119 .\" this is the interface number within a device that an interface driver
122 .\" this is the 16 bit vendor id of the device.
124 .\" this is the 16 bit product id of the device.
126 .\" this is the 16 bit release (revision) number of the device.
128 .\" The first locator can be used to pin down a particular device
129 .\" according to its physical position in the device tree.
130 .\" The last three locators can be used to pin down a particular
131 .\" device according to what device it actually is.
133 The bus enumeration of the
135 bus proceeds in several steps:
138 Any device specific driver can attach to the device.
140 If none is found, any device class specific driver can attach.
142 If none is found, all configurations are iterated over.
143 For each configuration, all the interfaces are iterated over, and interface
145 If any interface driver attached in a certain
146 configuration, the iteration over configurations is stopped.
148 If still no drivers have been found, the generic
152 .Sh USB CONTROLLER INTERFACE
153 Use the following to get access to the
155 specific structures and defines.
159 can be opened and a few operations can be performed on it.
162 system call will say that I/O is possible on the controller device when a
164 device has been connected or disconnected to the bus.
168 commands are supported on the controller device:
169 .Bl -tag -width xxxxxx
171 This command will cause a complete bus discovery to be initiated.
172 If any devices attached or detached from the bus they will be
173 processed during this command.
174 This is the only way that new devices are found on the bus.
175 .It Dv USB_DEVICEINFO Vt "struct usb_device_info"
176 This command can be used to retrieve some information about a device
180 field should be filled before the call and the other fields will
181 be filled by information about the device on that address.
182 Should no such device exist, an error is reported.
184 #define USB_MAX_DEVNAMES 4
185 #define USB_MAX_DEVNAMELEN 16
186 struct usb_device_info {
188 u_int8_t udi_addr; /* device address */
189 usb_event_cookie_t udi_cookie;
190 char udi_product[USB_MAX_STRING_LEN];
191 char udi_vendor[USB_MAX_STRING_LEN];
193 u_int16_t udi_productNo;
194 u_int16_t udi_vendorNo;
195 u_int16_t udi_releaseNo;
197 u_int8_t udi_subclass;
198 u_int8_t udi_protocol;
201 #define USB_SPEED_LOW 1
202 #define USB_SPEED_FULL 2
203 #define USB_SPEED_HIGH 3
204 int udi_power;/* power consumption in mA, 0 if selfpowered */
206 char udi_devnames[USB_MAX_DEVNAMES][USB_MAX_DEVNAMELEN];
207 u_int8_t udi_ports[16];/* hub only: addresses of devices on ports */
208 #define USB_PORT_ENABLED 0xff
209 #define USB_PORT_SUSPENDED 0xfe
210 #define USB_PORT_POWERED 0xfd
211 #define USB_PORT_DISABLED 0xfc
218 contain the topological information for the device.
220 contains the device names of the connected drivers.
224 Zip drive connected will be
227 .Va udi_product , udi_vendor
230 fields contain self-explanatory descriptions of the device.
231 .Va udi_productNo , udi_vendorNo , udi_releaseNo , udi_class , udi_subclass
234 contain the corresponding values from the device descriptors.
237 field shows the current configuration of the device.
240 indicates whether the device is at low speed
241 .Pq Dv USB_SPEED_LOW ,
243 .Pq Dv USB_SPEED_FULL
245 .Pq Dv USB_SPEED_HIGH .
248 field shows the power consumption in milli-amps drawn at 5 volts,
249 or zero if the device is self powered.
251 If the device is a hub, the
253 field is non-zero, and the
255 field contains the addresses of the connected devices.
256 If no device is connected to a port, one of the
258 values indicates its status.
259 .It Dv USB_DEVICESTATS Vt "struct usb_device_stats"
260 This command retrieves statistics about the controller.
262 struct usb_device_stats {
263 u_long uds_requests[4];
269 field is indexed by the transfer kind, i.e.\&
271 and indicates how many transfers of each kind that has been completed
273 .It Dv USB_REQUEST Vt "struct usb_ctl_request"
274 This command can be used to execute arbitrary requests on the control pipe.
277 and should be used with great care since it
278 can destroy the bus integrity.
283 contains definitions for the types used by the various
286 The naming convention of the fields for the various
288 descriptors exactly follows the naming in the
291 Byte sized fields can be accessed directly, but word (16 bit)
292 sized fields must be access by the
295 .Fn USETW field value
296 macros to handle byte order and alignment properly.
300 similarly contains the definitions for
301 Human Interface Devices
303 .Sh USB EVENT INTERFACE
306 events are reported via the
309 This devices can be opened for reading and each
311 will yield an event record (if something has happened).
314 system call can be used to determine if an event record is available
317 The event record has the following definition:
321 #define USB_EVENT_CTRLR_ATTACH 1
322 #define USB_EVENT_CTRLR_DETACH 2
323 #define USB_EVENT_DEVICE_ATTACH 3
324 #define USB_EVENT_DEVICE_DETACH 4
325 #define USB_EVENT_DRIVER_ATTACH 5
326 #define USB_EVENT_DRIVER_DETACH 6
327 struct timespec ue_time;
332 struct usb_device_info ue_device;
334 usb_event_cookie_t ue_cookie;
342 field identifies the type of event that is described.
343 The possible events are attach/detach of a host controller,
344 a device, or a device driver.
345 The union contains information
346 pertinent to the different types of events.
348 .Fn USB_EVENT_IS_ATTACH "ue_type"
350 .Fn USB_EVENT_IS_DETACH "ue_type"
351 can be used to determine if an event was an
359 contains the number of the
361 bus for host controller events.
365 record contains information about the device in a device event event.
369 is an opaque value that uniquely determines which
370 device a device driver has been attached to (i.e., it equals
371 the cookie value in the device that the driver attached to).
375 contains the name of the device (driver) as seen in, e.g.,
378 Note that there is a separation between device and device
380 A device event is generated when a physical
382 device is attached or detached.
386 have zero, one, or many device drivers associated with it.
390 specifications can be found at:
392 .D1 Pa http://www.usb.org/developers/docs/
416 driver first appeared in
421 driver was written by
422 .An Lennart Augustsson Aq augustss@carlstedt.se