1.\" 2.\" Copyright (c) 2009 Sylvestre Gallon 3.\" 4.\" All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 15.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 16.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 17.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 18.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 19.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 20.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 21.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 22.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 25.\" SUCH DAMAGE. 26.\" 27.\" $FreeBSD$ 28.\" 29.Dd August 16, 2011 30.Dt LIBUSB 3 31.Os 32.Sh NAME 33.Nm libusb 34. 35.Nd "USB access library" 36. 37. 38.Sh LIBRARY 39. 40. 41USB access library (libusb -lusb) 42. 43. 44.Sh SYNOPSIS 45. 46. 47.In libusb.h 48. 49. 50.Sh DESCRIPTION 51The 52.Nm 53library contains interfaces for directly managing a usb device. 54The current implementation supports v1.0 of the libusb API. 55. 56. 57.Sh LIBRARY INITIALISATION / DEINITIALISATION 58. 59.Pp 60. 61.Ft int 62.Fn libusb_init libusb_context **ctx 63This function initialises libusb. Must be called at the beginning 64of the program. This function returns 0 on success or LIBUSB_ERROR on 65failure. 66. 67.Pp 68. 69.Ft void 70.Fn libusb_exit "libusb_context *ctx" 71Deinitialise libusb. Must be called at the end of the application. 72. 73.Pp 74. 75.Ft const char * 76.Fn libusb_strerror "int code" 77Get ASCII representation of the error given by the 78.Fa code 79argument. 80. 81. 82.Pp 83. 84.Ft void 85.Fn libusb_set_debug "libusb_context *ctx" "int level" 86Set debug to the 87.Fa level 88level. 89. 90.Pp 91. 92.Ft ssize_t 93.Fn libusb_get_device_list "libusb_context *ctx" "libusb_device ***list" 94Fill into 95.Fa list 96the list of usb device available. All the device created by this 97function must be unref and free when you are done with them. This 98function returns the number of devices in list or a LIBUSB_ERROR code. 99. 100.Pp 101. 102.Ft void 103.Fn libusb_free_device_list "libusb_device **list" "int unref_devices" 104Free the list of devices discovered by libusb_get_device_list. If 105.Fa unref_device 106is set to 1 all devices are unref one time. 107. 108.Pp 109. 110.Ft uint8_t 111.Fn libusb_get_bus_number "libusb_device *dev" 112Returns the number of the bus contained by the device 113.Fa dev. 114. 115.Pp 116. 117.Ft uint8_t 118.Fn libusb_get_device_address "libusb_device *dev" 119Returns the device_address contained by the device 120.Fa dev. 121. 122.Pp 123. 124.Ft enum libusb_speed 125.Fn libusb_get_device_speed "libusb_device *dev" 126Returns the wire speed at which the device is connected. 127See the LIBUSB_SPEED_XXX enums for more information. 128LIBUSB_SPEED_UNKNOWN is returned in case of unknown wire speed. 129. 130.Pp 131. 132.Ft int 133.Fn libusb_get_max_packet_size "libusb_device *dev" "unsigned char endpoint" 134Returns the wMaxPacketSize value on success, LIBUSB_ERROR_NOT_FOUND if the 135endpoint does not exist and LIBUSB_ERROR_OTHERS on other failure. 136. 137.Pp 138. 139.Ft libusb_device * 140.Fn libusb_ref_device "libusb_device *dev" 141Increment the reference counter of the device 142.Fa dev. 143. 144.Pp 145. 146.Ft void 147.Fn libusb_unref_device "libusb_device *dev" 148Decrement the reference counter of the device 149.Fa dev. 150. 151.Pp 152. 153.Ft int 154.Fn libusb_open "libusb_device *dev" "libusb_device_handle **devh" 155Open a device and obtain a device_handle. Returns 0 on success, 156LIBUSB_ERROR_NO_MEM on memory allocation problem, LIBUSB_ERROR_ACCESS 157on permission problem, LIBUSB_ERROR_NO_DEVICE if the device has been 158disconnected and a LIBUSB_ERROR code on error. 159. 160.Pp 161. 162.Ft libusb_device_handle * 163.Fn libusb_open_device_with_vid_pid "libusb_context *ctx" "uint16_t vid" "uint16_t pid" 164Convenience function to open a device with is 165.Fa vid 166and 167.Fa pid. 168Returns NULL on error. 169. 170.Pp 171. 172.Ft void 173.Fn libusb_close "libusb_device_handle *devh" 174Close a device handle. 175. 176.Pp 177. 178.Ft libusb_device * 179.Fn libusb_get_device "libusb_device_handle *devh" 180Get the device contained by devh. 181Returns NULL on error. 182. 183.Pp 184. 185.Ft int 186.Fn libusb_get_configuration "libusb_device_handle *devh" "int *config" 187Returns the bConfiguration value of the current configuration. Returns 0 188on success, LIBUSB_ERROR_NO_DEVICE if the device has been disconnected 189and a LIBUSB_ERROR code on error. 190. 191.Pp 192. 193.Ft int 194.Fn libusb_set_configuration "libusb_device_handle *devh" "int config" 195Set the active configuration 196.Fa config 197for the device contained by 198.Fa devh. 199This function returns 0 on success, LIBUSB_ERROR_NOT_FOUND if the requested 200configuration does not exist, LIBUSB_ERROR_BUSY if the interfaces are currently 201claimed, LIBUSB_ERROR_NO_DEVICE if the device has been disconnected and a 202LIBUSB_ERROR code on failure. 203. 204.Pp 205. 206.Ft int 207.Fn libusb_claim_interface "libusb_device_handle *devh" "int interface_number" 208Claim an interface in a given libusb_handle 209.Fa devh. 210This is a non-blocking function. It returns 0 success, LIBUSB_ERROR_NOT_FOUND 211if the requested interface does not exist, LIBUSB_ERROR_BUSY if a program or 212driver has claimed the interface, LIBUSB_ERROR_NO_DEVICE if the device has 213been disconnected and a LIBUSB_ERROR code on failure. 214. 215.Pp 216. 217.Ft int 218.Fn libusb_release_interface "libusb_device_handle *devh" "int interface_number" 219This function release an interface. All the claimed interface must be released 220before closing a device. Returns 0 on success, LIBUSB_ERROR_NOT_FOUND if the 221interface was not claimed, LIBUSB_ERROR_NO_DEVICE if the device has been 222disconnected and LIBUSB_ERROR on failure. 223. 224.Pp 225. 226.Ft int 227.Fn libusb_set_interface_alt_setting "libusb_device_handle *dev" "int interface_number" "int alternate_setting" 228Activate an alternate setting for an interface. Returns 0 on success, 229LIBUSB_ERROR_NOT_FOUND if the interface was not claimed or the requested 230setting does not exist, LIBUSB_ERROR_NO_DEVICE if the device has been 231disconnected and LIBUSB_ERROR code on failure. 232. 233.Pp 234. 235.Ft int 236.Fn libusb_clear_halt "libusb_device_handle *devh" "unsigned char endpoint" 237Clear an halt/stall for a endpoint. Returns 0 on success, LIBUSB_ERROR_NOT_FOUND 238if the endpoint does not exist, LIBUSB_ERROR_NO_DEVICE if the device has been 239disconnected and a LIBUSB_ERROR code on failure. 240. 241.Pp 242. 243.Ft int 244.Fn libusb_reset_device "libusb_device_handle *devh" 245Perform an USB port reset for an usb device. Returns 0 on success, 246LIBUSB_ERROR_NOT_FOUND if re-enumeration is required or if the device has 247been disconnected and a LIBUSB_ERROR code on failure. 248. 249.Pp 250. 251.Ft int 252.Fn libusb_check_connected "libusb_device_handle *devh" 253Test if USB device is still connected. Returns 0 on success, 254LIBUSB_ERROR_NO_DEVICE if has been disconnected and a LIBUSB_ERROR 255code on failure. 256. 257.Pp 258. 259.Ft int 260.Fn libusb_kernel_driver_active "libusb_device_handle *devh" "int interface" 261Determine if a driver is active on a interface. Returns 0 if no kernel driver 262is active, returns 1 if a kernel driver is active, returns LIBUSB_ERROR_NO_DEVICE 263if the device has been disconnected and returns a LIBUSB_ERROR code on failure. 264. 265.Pp 266. 267.Ft int 268.Fn libusb_get_driver "libusb_device_handle *devh" "int interface" "char *name" "int namelen" 269or 270.Ft int 271.Fn libusb_get_driver_np "libusb_device_handle *devh" "int interface" "char *name" "int namelen" 272Gets the name of the driver attached to the given 273.Fa device 274and 275.Fa interface 276into the buffer given by 277.Fa name 278and 279.Fa namelen . 280Returns 0 on success, LIBUSB_ERROR_NOT_FOUND if no kernel driver is attached 281to the given interface and LIBUSB_ERROR_INVALID_PARAM if the interface does 282not exist. 283This function is non-portable. 284The buffer pointed to by 285.Fa name 286is only zero terminated on success. 287. 288.Pp 289. 290.Ft int 291.Fn libusb_detach_kernel_driver "libusb_device_handle *devh" "int interface" 292or 293.Ft int 294.Fn libusb_detach_kernel_driver_np "libusb_device_handle *devh" "int interface" 295Detach a kernel driver from an interface. 296This is needed to claim an interface required by a kernel driver. 297Returns 0 on success, LIBUSB_ERROR_NOT_FOUND if no kernel driver was active, 298LIBUSB_ERROR_INVALID_PARAM if the interface does not exist, LIBUSB_ERROR_NO_DEVICE if the device has been disconnected and a LIBUSB_ERROR code on failure. This function is non-portable. 299. 300.Pp 301. 302.Ft int 303.Fn libusb_attach_kernel_driver "libusb_device_handle *devh" "int interface" 304Re-attach an interface kernel driver previously detached. Returns 0 on success, 305LIBUSB_ERROR_INVALID_PARAM if the interface does not exist, LIBUSB_ERROR_NO_DEVICE 306if the device has been disconnect, LIBUSB_ERROR_BUSY if the driver cannot be 307attached because the interface is claimed by a program or driver and a 308LIBUSB_ERROR code on failure. 309. 310.Pp 311. 312.Sh USB DESCRIPTORS 313. 314.Pp 315. 316.Ft int 317.Fn libusb_get_device_descriptor "libusb_device *dev" "libusb_device_descriptor *desc" 318Get the USB device descriptor for the device 319.Fa dev. 320This is a non-blocking function. Returns 0 on success and a LIBUSB_ERROR code on 321failure. 322. 323.Pp 324.Ft int 325.Fn libsub_get_active_config_descriptor "libusb_device *dev" "struct libusb_config_descriptor **config" 326Get the USB configuration descriptor for the active configuration. Returns 0 on 327success, returns LIBUSB_ERROR_NOT_FOUND if the device is in unconfigured state 328and returns another LIBUSB_ERROR code on error. 329. 330.Pp 331.Ft int 332.Fn libusb_get_config_descriptor "libusb_device *dev" "uint8_t config_index" "libusb_config_descriptor **config" 333Get USB configuration descriptor based on its index 334.Fa idx. 335Returns 0 on success, LIBUSB_ERROR_NOT_FOUND if the configuration does not exist 336and returns another LIBUSB_ERROR code on error. 337. 338.Pp 339.Ft int 340.Fn libusb_get_config_descriptor_by_value "libusb_device *dev" "uint8 bConfigurationValue" "libusb_config_descriptor **config" 341Get a USB configuration descriptor with a specific bConfigurationValue. This is 342a non-blocking function which does not send request through the device. Returns 0 343on success, LIBUSB_ERROR_NOT_FOUND if the configuration does not exist and another 344LIBUSB_ERROR code on failure. 345. 346.Pp 347.Ft void 348.Fn libusb_free_config_descriptor "libusb_config_descriptor *config" 349Free a configuration descriptor. 350. 351.Pp 352.Ft int 353.Fn libusb_get_string_descriptor_ascii "libusb_device_handle *devh" "uint8_t desc_idx" "unsigned char *data" "int length" 354Retrieve a string descriptor in C style ascii. 355Returns a positive number of bytes in the resulting ASCII string on success and a LIBUSB_ERROR code on failure. 356. 357.Pp 358. 359.Sh USB ASYNCHRONOUS I/O 360. 361.Pp 362.Ft struct libusb_transfer * 363.Fn libusb_alloc_transfer "int iso_packets" 364Allocate a transfer with 365.Fa iso_packets 366numbers of isochronous packet descriptors. 367Returns NULL on error. 368. 369.Pp 370.Ft void 371.Fn libusb_free_transfer "struct libusb_transfer *tr" 372Free a transfer. 373. 374.Pp 375.Ft int 376.Fn libusb_submit_transfer "struct libusb_transfer *tr" 377This function will submit a transfer and returns immediately. 378Returns 0 on success, LIBUSB_ERROR_NO_DEVICE if the device has been disconnected and 379LIBUSB_ERROR code on other failure. 380. 381.Pp 382.Ft int 383.Fn libusb_cancel_transfer "struct libusb_transfer *tr" 384This function asynchronously cancel a transfer. 385Returns 0 on success and LIBUSB_ERROR code on failure. 386. 387.Pp 388.Sh USB SYNCHRONOUS I/O 389. 390.Pp 391.Ft int 392.Fn libusb_control_transfer "libusb_device_handle *devh" "uint8_t bmRequestType" "uint8_t bRequest" "uint16_t wValue" "uint16_t wIndex" "unsigned char *data" "uint16_t wLength" "unsigned int timeout" 393Perform a USB control transfer. 394Returns the actual number of bytes 395transferred on success in the range from and including zero until and 396including 397.Fa wLength . 398On error a libusb error code is returned, for example 399LIBUSB_ERROR_TIMEOUT if the transfer timeout, LIBUSB_ERROR_PIPE if the 400control request was not supported, LIBUSB_ERROR_NO_DEVICE if the 401device has been disconnected or another LIBUSB_ERROR code on other failures. 402The libusb error codes are always negative. 403. 404.Pp 405.Ft int 406.Fn libusb_bulk_transfer "struct libusb_device_handle *devh" "unsigned char endpoint" "unsigned char *data" "int length" "int *transferred" "unsigned int timeout" 407Perform an USB bulk transfer. 408A timeout value of zero means no timeout. 409The timeout value is given in milliseconds. 410Returns 0 on success, LIBUSB_ERROR_TIMEOUT 411if the transfer timeout, LIBUSB_ERROR_PIPE if the control request was not 412supported, LIBUSB_ERROR_OVERFLOW if the device offered more data, 413LIBUSB_ERROR_NO_DEVICE if the device has been disconnected and 414LIBUSB_ERROR code on other failure. 415. 416.Pp 417.Ft int 418.Fn libusb_interrupt_transfer "struct libusb_device_handle *devh" "unsigned char endpoint" "unsigned char *data" "int length" "int *transferred" "unsigned int timeout" 419Perform an USB Interrupt transfer. 420A timeout value of zero means no timeout. 421The timeout value is given in milliseconds. 422Returns 0 on success, LIBUSB_ERROR_TIMEOUT 423if the transfer timeout, LIBUSB_ERROR_PIPE if the control request was not 424supported, LIBUSB_ERROR_OVERFLOW if the device offered more data, 425LIBUSB_ERROR_NO_DEVICE if the device has been disconnected and 426LIBUSB_ERROR code on other failure. 427. 428.Pp 429.Sh USB EVENTS 430. 431.Pp 432.Ft int 433.Fn libusb_try_lock_events "libusb_context *ctx" 434Try to acquire the event handling lock. 435Returns 0 if the lock was obtained and 1 if not. 436. 437.Pp 438.Ft void 439.Fn libusb_lock_events "libusb_context *ctx" 440Acquire the event handling lock. This function is blocking. 441. 442.Pp 443.Ft void 444.Fn libusb_unlock_events "libusb_context *ctx" 445Release the event handling lock. This will wake up any thread blocked 446on libusb_wait_for_event(). 447. 448.Pp 449.Ft int 450.Fn libusb_event_handling_ok "libusb_context *ctx" 451Determine if it still OK for this thread to be doing event handling. Returns 1 452if event handling can start or continue. Returns 0 if this thread must give up 453the events lock. 454. 455.Pp 456.Ft int 457.Fn libusb_event_handler_active "libusb_context *ctx" 458Determine if an active thread is handling events. Returns 1 if yes and 0 if there 459are no threads currently handling events. 460. 461.Pp 462.Ft void 463.Fn libusb_lock_event_waiters "libusb_context *ctx" 464Acquire the event_waiters lock. This lock is designed to be obtained under the 465situation where you want to be aware when events are completed, but some other 466thread is event handling so calling libusb_handle_events() is not allowed. 467. 468.Pp 469.Ft void 470.Fn libusb_unlock_event_waiters "libusb_context *ctx" 471Release the event_waiters lock. 472. 473.Pp 474.Ft int 475.Fn libusb_wait_for_event "libusb_context *ctx" "struct timeval *tv" 476Wait for another thread to signal completion of an event. Must be called 477with the event waiters lock held, see libusb_lock_event_waiters(). This will 478block until the timeout expires or a transfer completes or a thread releases 479the event handling lock through libusb_unlock_events(). Returns 0 after a 480transfer completes or another thread stops event handling, returns 1 if the 481timeout expired. 482. 483.Pp 484.Ft int 485.Fn libusb_handle_events_timeout "libusb_context *ctx" "struct timeval *tv" 486Handle any pending events by checking if timeouts have expired and by 487checking the set of file descriptors for activity. Returns 0 on success, or a 488LIBUSB_ERROR code on failure. 489. 490.Pp 491.Ft int 492.Fn libusb_handle_events "libusb_context *ctx" 493Handle any pending events in blocking mode with a sensible timeout. Returns 0 494on success, returns a LIBUSB_ERROR code on failure. 495. 496.Pp 497.Ft int 498.Fn libusb_handle_events_locked "libusb_context *ctx" "struct timeval *tv" 499Handle any pending events by polling file desciptors, without checking if 500another threads are already doing so. Must be called with the event lock held. 501. 502.Pp 503.Ft int 504.Fn libusb_get_next_timeout "libusb_context *ctx" "struct timeval *tv" 505Determine the next internal timeout that libusb needs to handle. Returns 0 506if there are no pending timeouts, 1 if a timeout was returned, or LIBUSB_ERROR 507code on failure. 508. 509.Pp 510.Ft void 511.Fn libusb_set_pollfd_notifiers "libusb_context *ctx" "libusb_pollfd_added_cb added_cb" "libusb_pollfd_removed_cb remove_cb" "void *user_data" 512Register notification functions for file descriptor additions/removals. 513These functions will be invoked for every new or removed file descriptor 514that libusb uses as an event source. 515. 516.Pp 517.Ft const struct libusb_pollfd ** 518.Fn libusb_get_pollfds "libusb_context *ctx" 519Retrive a list of file descriptors that should be polled by your main loop as 520libusb event sources. Returns a NULL-terminated list on success or NULL on failure. 521. 522.Sh LIBUSB VERSION 0.1 COMPATIBILITY 523.Pp 524The library is also compliant with LibUSB version 0.1.12. 525.Pp 526.Fn usb_open 527.Fn usb_close 528.Fn usb_get_string 529.Fn usb_get_string_simple 530.Fn usb_get_descriptor_by_endpoint 531.Fn usb_get_descriptor 532.Fn usb_parse_descriptor 533.Fn usb_parse_configuration 534.Fn usb_destroy_configuration 535.Fn usb_fetch_and_parse_descriptors 536.Fn usb_bulk_write 537.Fn usb_bulk_read 538.Fn usb_interrupt_write 539.Fn usb_interrupt_read 540.Fn usb_control_msg 541.Fn usb_set_configuration 542.Fn usb_claim_interface 543.Fn usb_release_interface 544.Fn usb_set_altinterface 545.Fn usb_resetep 546.Fn usb_clear_halt 547.Fn usb_reset 548.Fn usb_strerror 549.Fn usb_init 550.Fn usb_set_debug 551.Fn usb_find_busses 552.Fn usb_find_devices 553.Fn usb_device 554.Fn usb_get_busses 555.Fn usb_check_connected 556.Fn usb_get_driver_np 557.Fn usb_detach_kernel_driver_np 558. 559.Sh SEE ALSO 560.Xr libusb20 3 , 561.Xr usb 4 , 562.Xr usbconfig 8 563.Pp 564.Pa http://libusb.sourceforge.net/ 565. 566.Sh HISTORY 567. 568.Nm 569support first appeared in 570.Fx 8.0 . 571