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LIBUSB(3)	       FreeBSD Library Functions Manual		     LIBUSB(3)

NAME
     libusb -- USB access library

LIBRARY
     USB access	library	(libusb, -lusb)

SYNOPSIS
     #include <libusb.h>

DESCRIPTION
     The libusb	library	contains interfaces for	directly managing a usb
     device.  The current implementation supports v1.0 of the libusb API.

LIBRARY	INITIALISATION / DEINITIALISATION
     int libusb_init(libusb_context, **ctx) This function initialises libusb.
     It	must be	called at the beginning	of the program,	before other libusb
     routines are used.	 This function returns 0 on success or LIBUSB_ERROR on
     failure.

     void libusb_exit(libusb_context *ctx) Deinitialise	libusb.	 Must be
     called at the end of the application.  Other libusb routines may not be
     called after this function.

     const char	* libusb_strerror(int code) Get	the ASCII representation of
     the error given by	the code argument.  This function does not return
     NULL.

     const char	* libusb_error_name(int	code) Get the ASCII representation of
     the error enum given by the code argument.	 This function does not	return
     NULL.

     void libusb_set_debug(libusb_context *ctx,	int level) Set the debug level
     to	level.

     ssize_t libusb_get_device_list(libusb_context *ctx, libusb_device
     ***list) Populate list with the list of usb devices available, adding a
     reference to each device in the list.  All	the list entries created by
     this function must	have their reference counter decremented when you are
     done with them, and the list itself must be freed.	 This function returns
     the number	of devices in the list or a LIBUSB_ERROR code.

     void libusb_free_device_list(libusb_device	**list,	int unref_devices)
     Free the list of devices discovered by libusb_get_device_list.  If
     unref_device is set to 1 all devices in the list have their reference
     counter decremented once.

     uint8_t libusb_get_bus_number(libusb_device *dev) Returns the number of
     the bus contained by the device dev.

     uint8_t libusb_get_device_address(libusb_device *dev) Returns the
     device_address contained by the device dev.

     enum libusb_speed libusb_get_device_speed(libusb_device *dev) Returns the
     wire speed	at which the device is connected.  See the LIBUSB_SPEED_XXX
     enums for more information.  LIBUSB_SPEED_UNKNOWN is returned in case of
     unknown wire speed.

     int libusb_get_max_packet_size(libusb_device *dev,	unsigned char
     endpoint) Returns the wMaxPacketSize value	on success,
     LIBUSB_ERROR_NOT_FOUND if the endpoint does not exist and
     LIBUSB_ERROR_OTHERS on other failure.

     int libusb_get_max_iso_packet_size(libusb_device *dev, unsigned char
     endpoint) Returns the packet size multiplied by the packet	multiplier on
     success, LIBUSB_ERROR_NOT_FOUND if	the endpoint does not exist and
     LIBUSB_ERROR_OTHERS on other failure.

     libusb_device * libusb_ref_device(libusb_device *dev) Increment the ref-
     erence counter of the device dev.

     void libusb_unref_device(libusb_device *dev) Decrement the	reference
     counter of	the device dev.

     int libusb_open(libusb_device *dev, libusb_device_handle **devh) Open a
     device and	obtain a device_handle.	 Returns 0 on success,
     LIBUSB_ERROR_NO_MEM on memory allocation problems,	LIBUSB_ERROR_ACCESS on
     permissions problems, LIBUSB_ERROR_NO_DEVICE if the device	has been dis-
     connected and a LIBUSB_ERROR code on other	errors.

     libusb_device_handle * libusb_open_device_with_vid_pid(libusb_context
     *ctx, uint16_t vid, uint16_t pid) A convenience function to open a	device
     by	vendor and product IDs vid and pid.  Returns NULL on error.

     void libusb_close(libusb_device_handle *devh) Close a device handle.

     libusb_device * libusb_get_device(libusb_device_handle *devh) Get the
     device contained by devh.	Returns	NULL on	error.

     int libusb_get_configuration(libusb_device_handle *devh, int *config)
     Returns the value of the current configuration.  Returns 0	on success,
     LIBUSB_ERROR_NO_DEVICE if the device has been disconnected	and a
     LIBUSB_ERROR code on error.

     int libusb_set_configuration(libusb_device_handle *devh, int config) Set
     the active	configuration to config	for the	device contained by devh.
     This function returns 0 on	success, LIBUSB_ERROR_NOT_FOUND	if the
     requested configuration does not exist, LIBUSB_ERROR_BUSY if the inter-
     faces are currently claimed, LIBUSB_ERROR_NO_DEVICE if the	device has
     been disconnected and a LIBUSB_ERROR code on failure.

     int libusb_claim_interface(libusb_device_handle *devh, int
     interface_number) Claim an	interface in a given libusb_handle devh.  This
     is	a non-blocking function.  It returns 0 on success,
     LIBUSB_ERROR_NOT_FOUND if the requested interface does not	exist,
     LIBUSB_ERROR_BUSY if a program or driver has claimed the interface,
     LIBUSB_ERROR_NO_DEVICE if the device has been disconnected	and a
     LIBUSB_ERROR code on failure.

     int libusb_release_interface(libusb_device_handle *devh, int
     interface_number) This function releases an interface.  All the claimed
     interfaces	on a device must be released before closing the	device.
     Returns 0 on success, LIBUSB_ERROR_NOT_FOUND if the interface was not
     claimed, LIBUSB_ERROR_NO_DEVICE if	the device has been disconnected and
     LIBUSB_ERROR on failure.

     int libusb_set_interface_alt_setting(libusb_device_handle *dev, int
     interface_number, int alternate_setting) Activate an alternate setting
     for an interface.	Returns	0 on success, LIBUSB_ERROR_NOT_FOUND if	the
     interface was not claimed or the requested	setting	does not exist,
     LIBUSB_ERROR_NO_DEVICE if the device has been disconnected	and a
     LIBUSB_ERROR code on failure.

     int libusb_clear_halt(libusb_device_handle	*devh, unsigned	char endpoint)
     Clear an halt/stall for a endpoint.  Returns 0 on success,
     LIBUSB_ERROR_NOT_FOUND if the endpoint does not exist,
     LIBUSB_ERROR_NO_DEVICE if the device has been disconnected	and a
     LIBUSB_ERROR code on failure.

     int libusb_reset_device(libusb_device_handle *devh) Perform an USB	port
     reset for an usb device.  Returns 0 on success, LIBUSB_ERROR_NOT_FOUND if
     re-enumeration is required	or if the device has been disconnected and a
     LIBUSB_ERROR code on failure.

     int libusb_check_connected(libusb_device_handle *devh) Test if the	USB
     device is still connected.	 Returns 0 on success, LIBUSB_ERROR_NO_DEVICE
     if	it has been disconnected and a LIBUSB_ERROR code on failure.

     int libusb_kernel_driver_active(libusb_device_handle *devh, int
     interface)	Determine if a driver is active	on a interface.	 Returns 0 if
     no	kernel driver is active	and 1 if a kernel driver is active,
     LIBUSB_ERROR_NO_DEVICE if the device has been disconnected	and a
     LIBUSB_ERROR code on failure.

     int libusb_get_driver(libusb_device_handle	*devh, int interface, char
     *name, int	namelen) or int	libusb_get_driver_np(libusb_device_handle
     *devh, int	interface, char	*name, int namelen) Copy the name of the
     driver attached to	the given device and interface into the	buffer name of
     length namelen.  Returns 0	on success, LIBUSB_ERROR_NOT_FOUND if no ker-
     nel driver	is attached to the given interface and
     LIBUSB_ERROR_INVALID_PARAM	if the interface does not exist.  This func-
     tion is non-portable.  The	buffer pointed to by name is only zero termi-
     nated on success.

     int libusb_detach_kernel_driver(libusb_device_handle *devh, int
     interface)	or int libusb_detach_kernel_driver_np(libusb_device_handle
     *devh, int	interface) Detach a kernel driver from an interface.  This is
     needed to claim an	interface already claimed by a kernel driver.  Returns
     0 on success, LIBUSB_ERROR_NOT_FOUND if no	kernel driver was active,
     LIBUSB_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.

     int libusb_attach_kernel_driver(libusb_device_handle *devh, int
     interface)	Re-attach an interface kernel driver that was previously
     detached.	Returns	0 on success, LIBUSB_ERROR_INVALID_PARAM if the	inter-
     face does not exist, LIBUSB_ERROR_NO_DEVICE if the	device has been	dis-
     connected,	LIBUSB_ERROR_BUSY if the driver	cannot be attached because the
     interface is claimed by a program or driver and a LIBUSB_ERROR code on
     failure.

USB DESCRIPTORS
     int libusb_get_device_descriptor(libusb_device *dev,
     libusb_device_descriptor *desc) Get the USB device	descriptor for the
     device dev.  This is a non-blocking function.  Returns 0 on success and a
     LIBUSB_ERROR code on failure.

     int libusb_get_active_config_descriptor(libusb_device *dev, struct
     libusb_config_descriptor **config)	Get the	USB configuration descriptor
     for the active configuration.  Returns 0 on success,
     LIBUSB_ERROR_NOT_FOUND if the device is in	an unconfigured	state and a
     LIBUSB_ERROR code on error.

     int libusb_get_config_descriptor(libusb_device *dev, uint8_t
     config_index, libusb_config_descriptor **config) Get a USB	configuration
     descriptor	based on its index idx.	Returns	0 on success,
     LIBUSB_ERROR_NOT_FOUND if the configuration does not exist	and a
     LIBUSB_ERROR code on error.

     int libusb_get_config_descriptor_by_value(libusb_device *dev, uint8
     bConfigurationValue, libusb_config_descriptor **config) Get a USB config-
     uration descriptor	with a specific	bConfigurationValue.  This is a	non-
     blocking function which does not send a request through the device.
     Returns 0 on success, LIBUSB_ERROR_NOT_FOUND if the configuration does
     not exist and a LIBUSB_ERROR code on failure.

     void libusb_free_config_descriptor(libusb_config_descriptor *config) Free
     a configuration descriptor.

     int libusb_get_string_descriptor_ascii(libusb_device_handle *devh,
     uint8_t desc_idx, unsigned	char *data, int	length)	Retrieve a string
     descriptor	in C style ASCII.  Returns the positive	number of bytes	in the
     resulting ASCII string on success and a LIBUSB_ERROR code on failure.

     int libusb_parse_ss_endpoint_comp(const void *buf,	int len,
     libusb_ss_endpoint_companion_descriptor **ep_comp)	This function parses
     the USB 3.0 endpoint companion descriptor in host endian format pointed
     to	by buf and having a length of len.  Typically these arguments are the
     extra and extra_length fields of the endpoint descriptor.	On success the
     pointer to	resulting descriptor is	stored at the location given by
     ep_comp.  Returns zero on success and a LIBUSB_ERROR code on failure.  On
     success the parsed	USB 3.0	endpoint companion descriptor must be freed
     using the libusb_free_ss_endpoint_comp function.

     void libusb_free_ss_endpoint_comp(libusb_ss_endpoint_companion_descriptor
     *ep_comp) This function is	NULL safe and frees a parsed USB 3.0 endpoint
     companion descriptor.

     int libusb_parse_bos_descriptor(const void	*buf, int len,
     libusb_bos_descriptor **bos) This function	parses a Binary	Object Store,
     BOS, descriptor into host endian format pointed to	by buf and having a
     length of len.  On	success	the pointer to resulting descriptor is stored
     at	the location given by bos.  Returns zero on success and	a LIBUSB_ERROR
     code on failure.  On success the parsed BOS descriptor must be freed
     using the libusb_free_bos_descriptor function.

     void libusb_free_bos_descriptor(libusb_bos_descriptor *bos) This function
     is	NULL safe and frees a parsed BOS descriptor.

USB ASYNCHRONOUS I/O
     struct libusb_transfer * libusb_alloc_transfer(int	iso_packets) Allocate
     a transfer	with the number	of isochronous packet descriptors specified by
     iso_packets.  Returns NULL	on error.

     void libusb_free_transfer(struct libusb_transfer *tr) Free	a transfer.

     int libusb_submit_transfer(struct libusb_transfer *tr) This function will
     submit a transfer and returns immediately.	 Returns 0 on success,
     LIBUSB_ERROR_NO_DEVICE if the device has been disconnected	and a
     LIBUSB_ERROR code on other	failure.

     int libusb_cancel_transfer(struct libusb_transfer *tr) This function
     asynchronously cancels a transfer.	 Returns 0 on success and a
     LIBUSB_ERROR code on failure.

USB SYNCHRONOUS	I/O
     int 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) Perform a
     USB control transfer.  Returns the	actual number of bytes transferred on
     success, in the range from	and including zero up to and including
     wLength.  On error	a LIBUSB_ERROR code is returned, for example
     LIBUSB_ERROR_TIMEOUT if the transfer timed	out, LIBUSB_ERROR_PIPE if the
     control request was not supported,	LIBUSB_ERROR_NO_DEVICE if the device
     has been disconnected and another LIBUSB_ERROR code on other failures.
     The LIBUSB_ERROR codes are	all negative.

     int libusb_bulk_transfer(struct libusb_device_handle *devh, unsigned char
     endpoint, unsigned	char *data, int	length,	int *transferred, unsigned int
     timeout) Perform an USB bulk transfer.  A timeout value of	zero means no
     timeout.  The timeout value is given in milliseconds.  Returns 0 on suc-
     cess, LIBUSB_ERROR_TIMEOUT	if the transfer	timed out, LIBUSB_ERROR_PIPE
     if	the control request was	not supported, LIBUSB_ERROR_OVERFLOW if	the
     device offered more data, LIBUSB_ERROR_NO_DEVICE if the device has	been
     disconnected and a	LIBUSB_ERROR code on other failure.

     int libusb_interrupt_transfer(struct libusb_device_handle *devh, unsigned
     char endpoint, unsigned char *data, int length, int *transferred,
     unsigned int timeout) Perform an USB Interrupt transfer.  A timeout value
     of	zero means no timeout.	The timeout value is given in milliseconds.
     Returns 0 on success, LIBUSB_ERROR_TIMEOUT	if the transfer	timed out,
     LIBUSB_ERROR_PIPE if the control request was not supported,
     LIBUSB_ERROR_OVERFLOW if the device offered more data,
     LIBUSB_ERROR_NO_DEVICE if the device has been disconnected	and a
     LIBUSB_ERROR code on other	failure.

USB EVENTS
     int libusb_try_lock_events(libusb_context *ctx) Try to acquire the	event
     handling lock.  Returns 0 if the lock was obtained	and 1 if not.

     void libusb_lock_events(libusb_context *ctx) Acquire the event handling
     lock.  This function is blocking.

     void libusb_unlock_events(libusb_context *ctx) Release the	event handling
     lock.  This will wake up any thread blocked on libusb_wait_for_event().

     int libusb_event_handling_ok(libusb_context *ctx) Determine if it still
     OK	for this thread	to be doing event handling.  Returns 1 if event	han-
     dling can start or	continue.  Returns 0 if	this thread must give up the
     events lock.

     int libusb_event_handler_active(libusb_context *ctx) Determine if an
     active thread is handling events.	Returns	1 if there is a	thread han-
     dling events and 0	if there are no	threads	currently handling events.

     void libusb_lock_event_waiters(libusb_context *ctx) Acquire the
     event_waiters lock.  This lock is designed	to be obtained in the situa-
     tion where	you want to be aware when events are completed,	but some other
     thread is event handling so calling libusb_handle_events()	is not
     allowed.

     void libusb_unlock_event_waiters(libusb_context *ctx) Release the
     event_waiters lock.

     int libusb_wait_for_event(libusb_context *ctx, struct timeval *tv)	Wait
     for another thread	to signal completion of	an event.  Must	be called with
     the event waiters lock held, see libusb_lock_event_waiters().  This will
     block until the timeout expires or	a transfer completes or	a thread
     releases the event	handling lock through libusb_unlock_events().  Returns
     0 after a transfer	completes or another thread stops event	handling, and
     1 if the timeout expired.

     int libusb_handle_events_timeout(libusb_context *ctx, struct timeval *tv)
     Handle any	pending	events by checking if timeouts have expired and	by
     checking the set of file descriptors for activity.	 Returns 0 on success,
     or	a LIBUSB_ERROR code on failure.

     int libusb_handle_events(libusb_context *ctx) Handle any pending events
     in	blocking mode with a sensible timeout.	Returns	0 on success and a
     LIBUSB_ERROR code on failure.

     int libusb_handle_events_locked(libusb_context *ctx, struct timeval *tv)
     Handle any	pending	events by polling file descriptors, without checking
     if	another	thread is already doing	so.  Must be called with the event
     lock held.

     int libusb_get_next_timeout(libusb_context	*ctx, struct timeval *tv)
     Determine the next	internal timeout that libusb needs to handle.  Returns
     0 if there	are no pending timeouts, 1 if a	timeout	was returned, or a
     LIBUSB_ERROR code on failure.

     void libusb_set_pollfd_notifiers(libusb_context *ctx,
     libusb_pollfd_added_cb added_cb, libusb_pollfd_removed_cb remove_cb, void
     *user_data) Register notification functions for file descriptor addi-
     tions/removals.  These functions will be invoked for every	new or removed
     file descriptor that libusb uses as an event source.

     const struct libusb_pollfd	** libusb_get_pollfds(libusb_context *ctx)
     Retrive a list of file descriptors	that should be polled by your main
     loop as libusb event sources.  Returns a NULL-terminated list on success
     or	NULL on	failure.

LIBUSB VERSION 0.1 COMPATIBILITY
     The library is also compliant with	LibUSB version 0.1.12.

     usb_open()	usb_close() usb_get_string() usb_get_string_simple()
     usb_get_descriptor_by_endpoint() usb_get_descriptor()
     usb_parse_descriptor() usb_parse_configuration()
     usb_destroy_configuration() usb_fetch_and_parse_descriptors()
     usb_bulk_write() usb_bulk_read() usb_interrupt_write()
     usb_interrupt_read() usb_control_msg() usb_set_configuration()
     usb_claim_interface() usb_release_interface() usb_set_altinterface()
     usb_resetep() usb_clear_halt() usb_reset()	usb_strerror() usb_init()
     usb_set_debug() usb_find_busses() usb_find_devices() usb_device()
     usb_get_busses() usb_check_connected() usb_get_driver_np()
     usb_detach_kernel_driver_np()

SEE ALSO
     libusb20(3), usb(4), usbconfig(8),	usbdump(8)

     http://libusb.sourceforge.net/

HISTORY
     libusb support first appeared in FreeBSD 8.0.

FreeBSD	9.2			April 12, 2012			   FreeBSD 9.2

NAME | LIBRARY | SYNOPSIS | DESCRIPTION | LIBRARY INITIALISATION / DEINITIALISATION | USB DESCRIPTORS | USB ASYNCHRONOUS I/O | USB SYNCHRONOUS I/O | USB EVENTS | LIBUSB VERSION 0.1 COMPATIBILITY | SEE ALSO | HISTORY

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