2 * Internal header for libusbx
3 * Copyright © 2007-2009 Daniel Drake <dsd@gentoo.org>
4 * Copyright © 2001 Johannes Erdfelt <johannes@erdfelt.com>
6 * This library is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Lesser General Public
8 * License as published by the Free Software Foundation; either
9 * version 2.1 of the License, or (at your option) any later version.
11 * This library is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * Lesser General Public License for more details.
16 * You should have received a copy of the GNU Lesser General Public
17 * License along with this library; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
37 /* Inside the libusbx code, mark all public functions as follows:
38 * return_type API_EXPORTED function_name(params) { ... }
39 * But if the function returns a pointer, mark it as follows:
40 * DEFAULT_VISIBILITY return_type * LIBUSB_CALL function_name(params) { ... }
41 * In the libusbx public header, mark all declarations as:
42 * return_type LIBUSB_CALL function_name(params);
44 #define API_EXPORTED LIBUSB_CALL DEFAULT_VISIBILITY
46 #define DEVICE_DESC_LENGTH 18
48 #define USB_MAXENDPOINTS 32
49 #define USB_MAXINTERFACES 32
50 #define USB_MAXCONFIG 8
53 struct list_head *prev, *next;
56 /* Get an entry from the list
57 * ptr - the address of this list_head element in "type"
58 * type - the data type that contains "member"
59 * member - the list_head element in "type"
61 #define list_entry(ptr, type, member) \
62 ((type *)((uintptr_t)(ptr) - (uintptr_t)(&((type *)0L)->member)))
64 /* Get each entry from a list
65 * pos - A structure pointer has a "member" element
67 * member - the list_head element in "pos"
68 * type - the type of the first parameter
70 #define list_for_each_entry(pos, head, member, type) \
71 for (pos = list_entry((head)->next, type, member); \
72 &pos->member != (head); \
73 pos = list_entry(pos->member.next, type, member))
75 #define list_for_each_entry_safe(pos, n, head, member, type) \
76 for (pos = list_entry((head)->next, type, member), \
77 n = list_entry(pos->member.next, type, member); \
78 &pos->member != (head); \
79 pos = n, n = list_entry(n->member.next, type, member))
81 #define list_empty(entry) ((entry)->next == (entry))
83 static inline void list_init(struct list_head *entry)
85 entry->prev = entry->next = entry;
88 static inline void list_add(struct list_head *entry, struct list_head *head)
90 entry->next = head->next;
93 head->next->prev = entry;
97 static inline void list_add_tail(struct list_head *entry,
98 struct list_head *head)
101 entry->prev = head->prev;
103 head->prev->next = entry;
107 static inline void list_del(struct list_head *entry)
109 entry->next->prev = entry->prev;
110 entry->prev->next = entry->next;
113 #define container_of(ptr, type, member) ({ \
114 const typeof( ((type *)0)->member ) *mptr = (ptr); \
115 (type *)( (char *)mptr - offsetof(type,member) );})
117 #define MIN(a, b) ((a) < (b) ? (a) : (b))
118 #define MAX(a, b) ((a) > (b) ? (a) : (b))
120 #define TIMESPEC_IS_SET(ts) ((ts)->tv_sec != 0 || (ts)->tv_nsec != 0)
122 void usbi_log(struct libusb_context *ctx, enum usbi_log_level level,
123 const char *function, const char *format, ...);
125 void usbi_log_v(struct libusb_context *ctx, enum usbi_log_level level,
126 const char *function, const char *format, va_list args);
128 #if !defined(_MSC_VER) || _MSC_VER >= 1400
130 #ifdef ENABLE_LOGGING
131 #define _usbi_log(ctx, level, ...) usbi_log(ctx, level, __FUNCTION__, __VA_ARGS__)
132 #define usbi_dbg(...) _usbi_log(NULL, LOG_LEVEL_DEBUG, __VA_ARGS__)
134 #define _usbi_log(ctx, level, ...) do { (void)(ctx); } while(0)
135 #define usbi_dbg(...) do {} while(0)
138 #define usbi_info(ctx, ...) _usbi_log(ctx, LOG_LEVEL_INFO, __VA_ARGS__)
139 #define usbi_warn(ctx, ...) _usbi_log(ctx, LOG_LEVEL_WARNING, __VA_ARGS__)
140 #define usbi_err(ctx, ...) _usbi_log(ctx, LOG_LEVEL_ERROR, __VA_ARGS__)
142 #else /* !defined(_MSC_VER) || _MSC_VER >= 1400 */
144 #ifdef ENABLE_LOGGING
145 #define LOG_BODY(ctxt, level) \
148 va_start (args, format); \
149 usbi_log_v(ctxt, level, "", format, args); \
153 #define LOG_BODY(ctxt, level) do { (void)(ctxt); } while(0)
156 static inline void usbi_info(struct libusb_context *ctx, const char *format,
158 LOG_BODY(ctx,LOG_LEVEL_INFO)
159 static inline void usbi_warn(struct libusb_context *ctx, const char *format,
161 LOG_BODY(ctx,LOG_LEVEL_WARNING)
162 static inline void usbi_err( struct libusb_context *ctx, const char *format,
164 LOG_BODY(ctx,LOG_LEVEL_ERROR)
166 static inline void usbi_dbg(const char *format, ...)
167 LOG_BODY(NULL,LOG_LEVEL_DEBUG)
169 #endif /* !defined(_MSC_VER) || _MSC_VER >= 1400 */
171 #define USBI_GET_CONTEXT(ctx) if (!(ctx)) (ctx) = usbi_default_context
172 #define DEVICE_CTX(dev) ((dev)->ctx)
173 #define HANDLE_CTX(handle) (DEVICE_CTX((handle)->dev))
174 #define TRANSFER_CTX(transfer) (HANDLE_CTX((transfer)->dev_handle))
175 #define ITRANSFER_CTX(transfer) \
176 (TRANSFER_CTX(USBI_TRANSFER_TO_LIBUSB_TRANSFER(transfer)))
178 #define IS_EPIN(ep) (0 != ((ep) & LIBUSB_ENDPOINT_IN))
179 #define IS_EPOUT(ep) (!IS_EPIN(ep))
180 #define IS_XFERIN(xfer) (0 != ((xfer)->endpoint & LIBUSB_ENDPOINT_IN))
181 #define IS_XFEROUT(xfer) (!IS_XFERIN(xfer))
183 /* Internal abstractions for thread synchronization and poll */
184 #if defined(THREADS_POSIX)
185 #include <os/threads_posix.h>
186 #elif defined(OS_WINDOWS)
187 #include <os/threads_windows.h>
190 #if defined(OS_LINUX) || defined(OS_DARWIN) || defined(OS_OPENBSD)
192 #include <os/poll_posix.h>
193 #elif defined(OS_WINDOWS)
194 #include <os/poll_windows.h>
197 #if defined(OS_WINDOWS) && !defined(__GCC__)
198 #undef HAVE_GETTIMEOFDAY
199 int usbi_gettimeofday(struct timeval *tp, void *tzp);
200 #define LIBUSB_GETTIMEOFDAY_WIN32
201 #define HAVE_USBI_GETTIMEOFDAY
203 #ifdef HAVE_GETTIMEOFDAY
204 #define usbi_gettimeofday(tv, tz) gettimeofday((tv), (tz))
205 #define HAVE_USBI_GETTIMEOFDAY
209 extern struct libusb_context *usbi_default_context;
211 struct libusb_context {
215 /* internal control pipe, used for interrupting event handling when
216 * something needs to modify poll fds. */
219 struct list_head usb_devs;
220 usbi_mutex_t usb_devs_lock;
222 /* A list of open handles. Backends are free to traverse this if required.
224 struct list_head open_devs;
225 usbi_mutex_t open_devs_lock;
227 /* this is a list of in-flight transfer handles, sorted by timeout
228 * expiration. URBs to timeout the soonest are placed at the beginning of
229 * the list, URBs that will time out later are placed after, and urbs with
230 * infinite timeout are always placed at the very end. */
231 struct list_head flying_transfers;
232 usbi_mutex_t flying_transfers_lock;
234 /* list of poll fds */
235 struct list_head pollfds;
236 usbi_mutex_t pollfds_lock;
238 /* a counter that is set when we want to interrupt event handling, in order
239 * to modify the poll fd set. and a lock to protect it. */
240 unsigned int pollfd_modify;
241 usbi_mutex_t pollfd_modify_lock;
243 /* user callbacks for pollfd changes */
244 libusb_pollfd_added_cb fd_added_cb;
245 libusb_pollfd_removed_cb fd_removed_cb;
246 void *fd_cb_user_data;
248 /* ensures that only one thread is handling events at any one time */
249 usbi_mutex_t events_lock;
251 /* used to see if there is an active thread doing event handling */
252 int event_handler_active;
254 /* used to wait for event completion in threads other than the one that is
256 usbi_mutex_t event_waiters_lock;
257 usbi_cond_t event_waiters_cond;
259 #ifdef USBI_TIMERFD_AVAILABLE
260 /* used for timeout handling, if supported by OS.
261 * this timerfd is maintained to trigger on the next pending timeout */
266 #ifdef USBI_TIMERFD_AVAILABLE
267 #define usbi_using_timerfd(ctx) ((ctx)->timerfd >= 0)
269 #define usbi_using_timerfd(ctx) (0)
272 struct libusb_device {
273 /* lock protects refcnt, everything else is finalized at initialization
278 struct libusb_context *ctx;
282 struct libusb_device* parent_dev;
283 uint8_t device_address;
284 uint8_t num_configurations;
285 enum libusb_speed speed;
287 struct list_head list;
288 unsigned long session_data;
289 unsigned char os_priv[0];
292 struct libusb_device_handle {
293 /* lock protects claimed_interfaces */
295 unsigned long claimed_interfaces;
297 struct list_head list;
298 struct libusb_device *dev;
299 unsigned char os_priv[0];
303 USBI_CLOCK_MONOTONIC,
307 /* in-memory transfer layout:
309 * 1. struct usbi_transfer
310 * 2. struct libusb_transfer (which includes iso packets) [variable size]
311 * 3. os private data [variable size]
313 * from a libusb_transfer, you can get the usbi_transfer by rewinding the
314 * appropriate number of bytes.
315 * the usbi_transfer includes the number of allocated packets, so you can
316 * determine the size of the transfer and hence the start and length of the
320 struct usbi_transfer {
322 struct list_head list;
323 struct timeval timeout;
327 /* this lock is held during libusb_submit_transfer() and
328 * libusb_cancel_transfer() (allowing the OS backend to prevent duplicate
329 * cancellation, submission-during-cancellation, etc). the OS backend
330 * should also take this lock in the handle_events path, to prevent the user
331 * cancelling the transfer from another thread while you are processing
332 * its completion (presumably there would be races within your OS backend
333 * if this were possible). */
337 enum usbi_transfer_flags {
338 /* The transfer has timed out */
339 USBI_TRANSFER_TIMED_OUT = 1 << 0,
341 /* Set by backend submit_transfer() if the OS handles timeout */
342 USBI_TRANSFER_OS_HANDLES_TIMEOUT = 1 << 1,
344 /* Cancellation was requested via libusb_cancel_transfer() */
345 USBI_TRANSFER_CANCELLING = 1 << 2,
347 /* Operation on the transfer failed because the device disappeared */
348 USBI_TRANSFER_DEVICE_DISAPPEARED = 1 << 3,
350 /* Set by backend submit_transfer() if the fds in use have been updated */
351 USBI_TRANSFER_UPDATED_FDS = 1 << 4,
354 #define USBI_TRANSFER_TO_LIBUSB_TRANSFER(transfer) \
355 ((struct libusb_transfer *)(((unsigned char *)(transfer)) \
356 + sizeof(struct usbi_transfer)))
357 #define LIBUSB_TRANSFER_TO_USBI_TRANSFER(transfer) \
358 ((struct usbi_transfer *)(((unsigned char *)(transfer)) \
359 - sizeof(struct usbi_transfer)))
361 static inline void *usbi_transfer_get_os_priv(struct usbi_transfer *transfer)
363 return ((unsigned char *)transfer) + sizeof(struct usbi_transfer)
364 + sizeof(struct libusb_transfer)
365 + (transfer->num_iso_packets
366 * sizeof(struct libusb_iso_packet_descriptor));
371 /* All standard descriptors have these 2 fields in common */
372 struct usb_descriptor_header {
374 uint8_t bDescriptorType;
377 /* shared data and functions */
379 int usbi_io_init(struct libusb_context *ctx);
380 void usbi_io_exit(struct libusb_context *ctx);
382 struct libusb_device *usbi_alloc_device(struct libusb_context *ctx,
383 unsigned long session_id);
384 struct libusb_device *usbi_get_device_by_session_id(struct libusb_context *ctx,
385 unsigned long session_id);
386 int usbi_sanitize_device(struct libusb_device *dev);
387 void usbi_handle_disconnect(struct libusb_device_handle *handle);
389 int usbi_handle_transfer_completion(struct usbi_transfer *itransfer,
390 enum libusb_transfer_status status);
391 int usbi_handle_transfer_cancellation(struct usbi_transfer *transfer);
393 int usbi_parse_descriptor(unsigned char *source, const char *descriptor,
394 void *dest, int host_endian);
395 int usbi_get_config_index_by_value(struct libusb_device *dev,
396 uint8_t bConfigurationValue, int *idx);
401 /* must come first */
402 struct libusb_pollfd pollfd;
404 struct list_head list;
407 int usbi_add_pollfd(struct libusb_context *ctx, int fd, short events);
408 void usbi_remove_pollfd(struct libusb_context *ctx, int fd);
409 void usbi_fd_notification(struct libusb_context *ctx);
411 /* device discovery */
413 /* we traverse usbfs without knowing how many devices we are going to find.
414 * so we create this discovered_devs model which is similar to a linked-list
415 * which grows when required. it can be freed once discovery has completed,
416 * eliminating the need for a list node in the libusb_device structure
418 struct discovered_devs {
421 struct libusb_device *devices[0];
424 struct discovered_devs *discovered_devs_append(
425 struct discovered_devs *discdevs, struct libusb_device *dev);
429 /* This is the interface that OS backends need to implement.
430 * All fields are mandatory, except ones explicitly noted as optional. */
431 struct usbi_os_backend {
432 /* A human-readable name for your backend, e.g. "Linux usbfs" */
435 /* Perform initialization of your backend. You might use this function
436 * to determine specific capabilities of the system, allocate required
437 * data structures for later, etc.
439 * This function is called when a libusbx user initializes the library
442 * Return 0 on success, or a LIBUSB_ERROR code on failure.
444 int (*init)(struct libusb_context *ctx);
446 /* Deinitialization. Optional. This function should destroy anything
447 * that was set up by init.
449 * This function is called when the user deinitializes the library.
453 /* Enumerate all the USB devices on the system, returning them in a list
454 * of discovered devices.
456 * Your implementation should enumerate all devices on the system,
457 * regardless of whether they have been seen before or not.
459 * When you have found a device, compute a session ID for it. The session
460 * ID should uniquely represent that particular device for that particular
461 * connection session since boot (i.e. if you disconnect and reconnect a
462 * device immediately after, it should be assigned a different session ID).
463 * If your OS cannot provide a unique session ID as described above,
464 * presenting a session ID of (bus_number << 8 | device_address) should
465 * be sufficient. Bus numbers and device addresses wrap and get reused,
466 * but that is an unlikely case.
468 * After computing a session ID for a device, call
469 * usbi_get_device_by_session_id(). This function checks if libusbx already
470 * knows about the device, and if so, it provides you with a libusb_device
473 * If usbi_get_device_by_session_id() returns NULL, it is time to allocate
474 * a new device structure for the device. Call usbi_alloc_device() to
475 * obtain a new libusb_device structure with reference count 1. Populate
476 * the bus_number and device_address attributes of the new device, and
477 * perform any other internal backend initialization you need to do. At
478 * this point, you should be ready to provide device descriptors and so
479 * on through the get_*_descriptor functions. Finally, call
480 * usbi_sanitize_device() to perform some final sanity checks on the
481 * device. Assuming all of the above succeeded, we can now continue.
482 * If any of the above failed, remember to unreference the device that
483 * was returned by usbi_alloc_device().
485 * At this stage we have a populated libusb_device structure (either one
486 * that was found earlier, or one that we have just allocated and
487 * populated). This can now be added to the discovered devices list
488 * using discovered_devs_append(). Note that discovered_devs_append()
489 * may reallocate the list, returning a new location for it, and also
490 * note that reallocation can fail. Your backend should handle these
491 * error conditions appropriately.
493 * This function should not generate any bus I/O and should not block.
494 * If I/O is required (e.g. reading the active configuration value), it is
495 * OK to ignore these suggestions :)
497 * This function is executed when the user wishes to retrieve a list
498 * of USB devices connected to the system.
500 * Return 0 on success, or a LIBUSB_ERROR code on failure.
502 int (*get_device_list)(struct libusb_context *ctx,
503 struct discovered_devs **discdevs);
505 /* Open a device for I/O and other USB operations. The device handle
506 * is preallocated for you, you can retrieve the device in question
507 * through handle->dev.
509 * Your backend should allocate any internal resources required for I/O
510 * and other operations so that those operations can happen (hopefully)
511 * without hiccup. This is also a good place to inform libusbx that it
512 * should monitor certain file descriptors related to this device -
513 * see the usbi_add_pollfd() function.
515 * This function should not generate any bus I/O and should not block.
517 * This function is called when the user attempts to obtain a device
518 * handle for a device.
522 * - LIBUSB_ERROR_ACCESS if the user has insufficient permissions
523 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since
525 * - another LIBUSB_ERROR code on other failure
527 * Do not worry about freeing the handle on failed open, the upper layers
530 int (*open)(struct libusb_device_handle *handle);
532 /* Close a device such that the handle cannot be used again. Your backend
533 * should destroy any resources that were allocated in the open path.
534 * This may also be a good place to call usbi_remove_pollfd() to inform
535 * libusbx of any file descriptors associated with this device that should
536 * no longer be monitored.
538 * This function is called when the user closes a device handle.
540 void (*close)(struct libusb_device_handle *handle);
542 /* Retrieve the device descriptor from a device.
544 * The descriptor should be retrieved from memory, NOT via bus I/O to the
545 * device. This means that you may have to cache it in a private structure
546 * during get_device_list enumeration. Alternatively, you may be able
547 * to retrieve it from a kernel interface (some Linux setups can do this)
548 * still without generating bus I/O.
550 * This function is expected to write DEVICE_DESC_LENGTH (18) bytes into
551 * buffer, which is guaranteed to be big enough.
553 * This function is called when sanity-checking a device before adding
554 * it to the list of discovered devices, and also when the user requests
555 * to read the device descriptor.
557 * This function is expected to return the descriptor in bus-endian format
558 * (LE). If it returns the multi-byte values in host-endian format,
559 * set the host_endian output parameter to "1".
561 * Return 0 on success or a LIBUSB_ERROR code on failure.
563 int (*get_device_descriptor)(struct libusb_device *device,
564 unsigned char *buffer, int *host_endian);
566 /* Get the ACTIVE configuration descriptor for a device.
568 * The descriptor should be retrieved from memory, NOT via bus I/O to the
569 * device. This means that you may have to cache it in a private structure
570 * during get_device_list enumeration. You may also have to keep track
571 * of which configuration is active when the user changes it.
573 * This function is expected to write len bytes of data into buffer, which
574 * is guaranteed to be big enough. If you can only do a partial write,
575 * return an error code.
577 * This function is expected to return the descriptor in bus-endian format
578 * (LE). If it returns the multi-byte values in host-endian format,
579 * set the host_endian output parameter to "1".
583 * - LIBUSB_ERROR_NOT_FOUND if the device is in unconfigured state
584 * - another LIBUSB_ERROR code on other failure
586 int (*get_active_config_descriptor)(struct libusb_device *device,
587 unsigned char *buffer, size_t len, int *host_endian);
589 /* Get a specific configuration descriptor for a device.
591 * The descriptor should be retrieved from memory, NOT via bus I/O to the
592 * device. This means that you may have to cache it in a private structure
593 * during get_device_list enumeration.
595 * The requested descriptor is expressed as a zero-based index (i.e. 0
596 * indicates that we are requesting the first descriptor). The index does
597 * not (necessarily) equal the bConfigurationValue of the configuration
600 * This function is expected to write len bytes of data into buffer, which
601 * is guaranteed to be big enough. If you can only do a partial write,
602 * return an error code.
604 * This function is expected to return the descriptor in bus-endian format
605 * (LE). If it returns the multi-byte values in host-endian format,
606 * set the host_endian output parameter to "1".
608 * Return 0 on success or a LIBUSB_ERROR code on failure.
610 int (*get_config_descriptor)(struct libusb_device *device,
611 uint8_t config_index, unsigned char *buffer, size_t len,
614 /* Get the bConfigurationValue for the active configuration for a device.
615 * Optional. This should only be implemented if you can retrieve it from
616 * cache (don't generate I/O).
618 * If you cannot retrieve this from cache, either do not implement this
619 * function, or return LIBUSB_ERROR_NOT_SUPPORTED. This will cause
620 * libusbx to retrieve the information through a standard control transfer.
622 * This function must be non-blocking.
625 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
627 * - LIBUSB_ERROR_NOT_SUPPORTED if the value cannot be retrieved without
629 * - another LIBUSB_ERROR code on other failure.
631 int (*get_configuration)(struct libusb_device_handle *handle, int *config);
633 /* Set the active configuration for a device.
635 * A configuration value of -1 should put the device in unconfigured state.
637 * This function can block.
641 * - LIBUSB_ERROR_NOT_FOUND if the configuration does not exist
642 * - LIBUSB_ERROR_BUSY if interfaces are currently claimed (and hence
643 * configuration cannot be changed)
644 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
646 * - another LIBUSB_ERROR code on other failure.
648 int (*set_configuration)(struct libusb_device_handle *handle, int config);
650 /* Claim an interface. When claimed, the application can then perform
651 * I/O to an interface's endpoints.
653 * This function should not generate any bus I/O and should not block.
654 * Interface claiming is a logical operation that simply ensures that
655 * no other drivers/applications are using the interface, and after
656 * claiming, no other drivers/applicatiosn can use the interface because
661 * - LIBUSB_ERROR_NOT_FOUND if the interface does not exist
662 * - LIBUSB_ERROR_BUSY if the interface is in use by another driver/app
663 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
665 * - another LIBUSB_ERROR code on other failure
667 int (*claim_interface)(struct libusb_device_handle *handle, int interface_number);
669 /* Release a previously claimed interface.
671 * This function should also generate a SET_INTERFACE control request,
672 * resetting the alternate setting of that interface to 0. It's OK for
673 * this function to block as a result.
675 * You will only ever be asked to release an interface which was
676 * successfully claimed earlier.
680 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
682 * - another LIBUSB_ERROR code on other failure
684 int (*release_interface)(struct libusb_device_handle *handle, int interface_number);
686 /* Set the alternate setting for an interface.
688 * You will only ever be asked to set the alternate setting for an
689 * interface which was successfully claimed earlier.
691 * It's OK for this function to block.
695 * - LIBUSB_ERROR_NOT_FOUND if the alternate setting does not exist
696 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
698 * - another LIBUSB_ERROR code on other failure
700 int (*set_interface_altsetting)(struct libusb_device_handle *handle,
701 int interface_number, int altsetting);
703 /* Clear a halt/stall condition on an endpoint.
705 * It's OK for this function to block.
709 * - LIBUSB_ERROR_NOT_FOUND if the endpoint does not exist
710 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
712 * - another LIBUSB_ERROR code on other failure
714 int (*clear_halt)(struct libusb_device_handle *handle,
715 unsigned char endpoint);
717 /* Perform a USB port reset to reinitialize a device.
719 * If possible, the handle should still be usable after the reset
720 * completes, assuming that the device descriptors did not change during
721 * reset and all previous interface state can be restored.
723 * If something changes, or you cannot easily locate/verify the resetted
724 * device, return LIBUSB_ERROR_NOT_FOUND. This prompts the application
725 * to close the old handle and re-enumerate the device.
729 * - LIBUSB_ERROR_NOT_FOUND if re-enumeration is required, or if the device
730 * has been disconnected since it was opened
731 * - another LIBUSB_ERROR code on other failure
733 int (*reset_device)(struct libusb_device_handle *handle);
735 /* Determine if a kernel driver is active on an interface. Optional.
737 * The presence of a kernel driver on an interface indicates that any
738 * calls to claim_interface would fail with the LIBUSB_ERROR_BUSY code.
741 * - 0 if no driver is active
742 * - 1 if a driver is active
743 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
745 * - another LIBUSB_ERROR code on other failure
747 int (*kernel_driver_active)(struct libusb_device_handle *handle,
748 int interface_number);
750 /* Detach a kernel driver from an interface. Optional.
752 * After detaching a kernel driver, the interface should be available
757 * - LIBUSB_ERROR_NOT_FOUND if no kernel driver was active
758 * - LIBUSB_ERROR_INVALID_PARAM if the interface does not exist
759 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
761 * - another LIBUSB_ERROR code on other failure
763 int (*detach_kernel_driver)(struct libusb_device_handle *handle,
764 int interface_number);
766 /* Attach a kernel driver to an interface. Optional.
768 * Reattach a kernel driver to the device.
772 * - LIBUSB_ERROR_NOT_FOUND if no kernel driver was active
773 * - LIBUSB_ERROR_INVALID_PARAM if the interface does not exist
774 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
776 * - LIBUSB_ERROR_BUSY if a program or driver has claimed the interface,
777 * preventing reattachment
778 * - another LIBUSB_ERROR code on other failure
780 int (*attach_kernel_driver)(struct libusb_device_handle *handle,
781 int interface_number);
783 /* Destroy a device. Optional.
785 * This function is called when the last reference to a device is
786 * destroyed. It should free any resources allocated in the get_device_list
789 void (*destroy_device)(struct libusb_device *dev);
791 /* Submit a transfer. Your implementation should take the transfer,
792 * morph it into whatever form your platform requires, and submit it
795 * This function must not block.
799 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
800 * - another LIBUSB_ERROR code on other failure
802 int (*submit_transfer)(struct usbi_transfer *itransfer);
804 /* Cancel a previously submitted transfer.
806 * This function must not block. The transfer cancellation must complete
807 * later, resulting in a call to usbi_handle_transfer_cancellation()
808 * from the context of handle_events.
810 int (*cancel_transfer)(struct usbi_transfer *itransfer);
812 /* Clear a transfer as if it has completed or cancelled, but do not
813 * report any completion/cancellation to the library. You should free
814 * all private data from the transfer as if you were just about to report
815 * completion or cancellation.
817 * This function might seem a bit out of place. It is used when libusbx
818 * detects a disconnected device - it calls this function for all pending
819 * transfers before reporting completion (with the disconnect code) to
820 * the user. Maybe we can improve upon this internal interface in future.
822 void (*clear_transfer_priv)(struct usbi_transfer *itransfer);
824 /* Handle any pending events. This involves monitoring any active
825 * transfers and processing their completion or cancellation.
827 * The function is passed an array of pollfd structures (size nfds)
828 * as a result of the poll() system call. The num_ready parameter
829 * indicates the number of file descriptors that have reported events
830 * (i.e. the poll() return value). This should be enough information
831 * for you to determine which actions need to be taken on the currently
834 * For any cancelled transfers, call usbi_handle_transfer_cancellation().
835 * For completed transfers, call usbi_handle_transfer_completion().
836 * For control/bulk/interrupt transfers, populate the "transferred"
837 * element of the appropriate usbi_transfer structure before calling the
838 * above functions. For isochronous transfers, populate the status and
839 * transferred fields of the iso packet descriptors of the transfer.
841 * This function should also be able to detect disconnection of the
842 * device, reporting that situation with usbi_handle_disconnect().
844 * When processing an event related to a transfer, you probably want to
845 * take usbi_transfer.lock to prevent races. See the documentation for
846 * the usbi_transfer structure.
848 * Return 0 on success, or a LIBUSB_ERROR code on failure.
850 int (*handle_events)(struct libusb_context *ctx,
851 struct pollfd *fds, POLL_NFDS_TYPE nfds, int num_ready);
853 /* Get time from specified clock. At least two clocks must be implemented
854 by the backend: USBI_CLOCK_REALTIME, and USBI_CLOCK_MONOTONIC.
856 Description of clocks:
857 USBI_CLOCK_REALTIME : clock returns time since system epoch.
858 USBI_CLOCK_MONOTONIC: clock returns time since unspecified start
861 int (*clock_gettime)(int clkid, struct timespec *tp);
863 #ifdef USBI_TIMERFD_AVAILABLE
864 /* clock ID of the clock that should be used for timerfd */
865 clockid_t (*get_timerfd_clockid)(void);
868 /* Number of bytes to reserve for per-device private backend data.
869 * This private data area is accessible through the "os_priv" field of
870 * struct libusb_device. */
871 size_t device_priv_size;
873 /* Number of bytes to reserve for per-handle private backend data.
874 * This private data area is accessible through the "os_priv" field of
875 * struct libusb_device. */
876 size_t device_handle_priv_size;
878 /* Number of bytes to reserve for per-transfer private backend data.
879 * This private data area is accessible by calling
880 * usbi_transfer_get_os_priv() on the appropriate usbi_transfer instance.
882 size_t transfer_priv_size;
884 /* Mumber of additional bytes for os_priv for each iso packet.
885 * Can your backend use this? */
886 /* FIXME: linux can't use this any more. if other OS's cannot either,
887 * then remove this */
888 size_t add_iso_packet_size;
891 extern const struct usbi_os_backend * const usbi_backend;
893 extern const struct usbi_os_backend linux_usbfs_backend;
894 extern const struct usbi_os_backend darwin_backend;
895 extern const struct usbi_os_backend openbsd_backend;
896 extern const struct usbi_os_backend windows_backend;