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 enum usbi_log_level {
129 void usbi_log(struct libusb_context *ctx, enum usbi_log_level level,
130 const char *function, const char *format, ...);
132 void usbi_log_v(struct libusb_context *ctx, enum usbi_log_level level,
133 const char *function, const char *format, va_list args);
135 #if !defined(_MSC_VER) || _MSC_VER >= 1400
137 #ifdef ENABLE_LOGGING
138 #define _usbi_log(ctx, level, ...) usbi_log(ctx, level, __FUNCTION__, __VA_ARGS__)
140 #define _usbi_log(ctx, level, ...) do { (void)(ctx); } while(0)
143 #ifdef ENABLE_DEBUG_LOGGING
144 #define usbi_dbg(...) _usbi_log(NULL, LOG_LEVEL_DEBUG, __VA_ARGS__)
146 #define usbi_dbg(...) do {} while(0)
149 #define usbi_info(ctx, ...) _usbi_log(ctx, LOG_LEVEL_INFO, __VA_ARGS__)
150 #define usbi_warn(ctx, ...) _usbi_log(ctx, LOG_LEVEL_WARNING, __VA_ARGS__)
151 #define usbi_err(ctx, ...) _usbi_log(ctx, LOG_LEVEL_ERROR, __VA_ARGS__)
153 #else /* !defined(_MSC_VER) || _MSC_VER >= 1400 */
155 #ifdef ENABLE_LOGGING
156 #define LOG_BODY(ctxt, level) \
159 va_start (args, format); \
160 usbi_log_v(ctxt, level, "", format, args); \
164 #define LOG_BODY(ctxt, level) do { (void)(ctxt); } while(0)
167 static inline void usbi_info(struct libusb_context *ctx, const char *format,
169 LOG_BODY(ctx,LOG_LEVEL_INFO)
170 static inline void usbi_warn(struct libusb_context *ctx, const char *format,
172 LOG_BODY(ctx,LOG_LEVEL_WARNING)
173 static inline void usbi_err( struct libusb_context *ctx, const char *format,
175 LOG_BODY(ctx,LOG_LEVEL_ERROR)
177 static inline void usbi_dbg(const char *format, ...)
178 #ifdef ENABLE_DEBUG_LOGGING
179 LOG_BODY(NULL,LOG_LEVEL_DEBUG)
184 #endif /* !defined(_MSC_VER) || _MSC_VER >= 1400 */
186 #define USBI_GET_CONTEXT(ctx) if (!(ctx)) (ctx) = usbi_default_context
187 #define DEVICE_CTX(dev) ((dev)->ctx)
188 #define HANDLE_CTX(handle) (DEVICE_CTX((handle)->dev))
189 #define TRANSFER_CTX(transfer) (HANDLE_CTX((transfer)->dev_handle))
190 #define ITRANSFER_CTX(transfer) \
191 (TRANSFER_CTX(USBI_TRANSFER_TO_LIBUSB_TRANSFER(transfer)))
193 #define IS_EPIN(ep) (0 != ((ep) & LIBUSB_ENDPOINT_IN))
194 #define IS_EPOUT(ep) (!IS_EPIN(ep))
195 #define IS_XFERIN(xfer) (0 != ((xfer)->endpoint & LIBUSB_ENDPOINT_IN))
196 #define IS_XFEROUT(xfer) (!IS_XFERIN(xfer))
198 /* Internal abstractions for thread synchronization and poll */
199 #if defined(THREADS_POSIX)
200 #include <os/threads_posix.h>
201 #elif defined(OS_WINDOWS)
202 #include <os/threads_windows.h>
205 #if defined(OS_LINUX) || defined(OS_DARWIN) || defined(OS_OPENBSD)
207 #include <os/poll_posix.h>
208 #elif defined(OS_WINDOWS)
209 #include <os/poll_windows.h>
212 #if defined(OS_WINDOWS) && !defined(__GCC__)
213 #undef HAVE_GETTIMEOFDAY
214 int usbi_gettimeofday(struct timeval *tp, void *tzp);
215 #define LIBUSB_GETTIMEOFDAY_WIN32
216 #define HAVE_USBI_GETTIMEOFDAY
218 #ifdef HAVE_GETTIMEOFDAY
219 #define usbi_gettimeofday(tv, tz) gettimeofday((tv), (tz))
220 #define HAVE_USBI_GETTIMEOFDAY
224 extern struct libusb_context *usbi_default_context;
226 struct libusb_context {
230 /* internal control pipe, used for interrupting event handling when
231 * something needs to modify poll fds. */
234 struct list_head usb_devs;
235 usbi_mutex_t usb_devs_lock;
237 /* A list of open handles. Backends are free to traverse this if required.
239 struct list_head open_devs;
240 usbi_mutex_t open_devs_lock;
242 /* this is a list of in-flight transfer handles, sorted by timeout
243 * expiration. URBs to timeout the soonest are placed at the beginning of
244 * the list, URBs that will time out later are placed after, and urbs with
245 * infinite timeout are always placed at the very end. */
246 struct list_head flying_transfers;
247 usbi_mutex_t flying_transfers_lock;
249 /* list of poll fds */
250 struct list_head pollfds;
251 usbi_mutex_t pollfds_lock;
253 /* a counter that is set when we want to interrupt event handling, in order
254 * to modify the poll fd set. and a lock to protect it. */
255 unsigned int pollfd_modify;
256 usbi_mutex_t pollfd_modify_lock;
258 /* user callbacks for pollfd changes */
259 libusb_pollfd_added_cb fd_added_cb;
260 libusb_pollfd_removed_cb fd_removed_cb;
261 void *fd_cb_user_data;
263 /* ensures that only one thread is handling events at any one time */
264 usbi_mutex_t events_lock;
266 /* used to see if there is an active thread doing event handling */
267 int event_handler_active;
269 /* used to wait for event completion in threads other than the one that is
271 usbi_mutex_t event_waiters_lock;
272 usbi_cond_t event_waiters_cond;
274 #ifdef USBI_TIMERFD_AVAILABLE
275 /* used for timeout handling, if supported by OS.
276 * this timerfd is maintained to trigger on the next pending timeout */
281 #ifdef USBI_TIMERFD_AVAILABLE
282 #define usbi_using_timerfd(ctx) ((ctx)->timerfd >= 0)
284 #define usbi_using_timerfd(ctx) (0)
287 struct libusb_device {
288 /* lock protects refcnt, everything else is finalized at initialization
293 struct libusb_context *ctx;
296 uint8_t device_address;
297 uint8_t num_configurations;
298 enum libusb_speed speed;
300 struct list_head list;
301 unsigned long session_data;
302 unsigned char os_priv[0];
305 struct libusb_device_handle {
306 /* lock protects claimed_interfaces */
308 unsigned long claimed_interfaces;
310 struct list_head list;
311 struct libusb_device *dev;
312 unsigned char os_priv[0];
316 USBI_CLOCK_MONOTONIC,
320 /* in-memory transfer layout:
322 * 1. struct usbi_transfer
323 * 2. struct libusb_transfer (which includes iso packets) [variable size]
324 * 3. os private data [variable size]
326 * from a libusb_transfer, you can get the usbi_transfer by rewinding the
327 * appropriate number of bytes.
328 * the usbi_transfer includes the number of allocated packets, so you can
329 * determine the size of the transfer and hence the start and length of the
333 struct usbi_transfer {
335 struct list_head list;
336 struct timeval timeout;
340 /* this lock is held during libusb_submit_transfer() and
341 * libusb_cancel_transfer() (allowing the OS backend to prevent duplicate
342 * cancellation, submission-during-cancellation, etc). the OS backend
343 * should also take this lock in the handle_events path, to prevent the user
344 * cancelling the transfer from another thread while you are processing
345 * its completion (presumably there would be races within your OS backend
346 * if this were possible). */
350 enum usbi_transfer_flags {
351 /* The transfer has timed out */
352 USBI_TRANSFER_TIMED_OUT = 1 << 0,
354 /* Set by backend submit_transfer() if the OS handles timeout */
355 USBI_TRANSFER_OS_HANDLES_TIMEOUT = 1 << 1,
357 /* Cancellation was requested via libusb_cancel_transfer() */
358 USBI_TRANSFER_CANCELLING = 1 << 2,
360 /* Operation on the transfer failed because the device disappeared */
361 USBI_TRANSFER_DEVICE_DISAPPEARED = 1 << 3,
363 /* Set by backend submit_transfer() if the fds in use have been updated */
364 USBI_TRANSFER_UPDATED_FDS = 1 << 4,
367 #define USBI_TRANSFER_TO_LIBUSB_TRANSFER(transfer) \
368 ((struct libusb_transfer *)(((unsigned char *)(transfer)) \
369 + sizeof(struct usbi_transfer)))
370 #define LIBUSB_TRANSFER_TO_USBI_TRANSFER(transfer) \
371 ((struct usbi_transfer *)(((unsigned char *)(transfer)) \
372 - sizeof(struct usbi_transfer)))
374 static inline void *usbi_transfer_get_os_priv(struct usbi_transfer *transfer)
376 return ((unsigned char *)transfer) + sizeof(struct usbi_transfer)
377 + sizeof(struct libusb_transfer)
378 + (transfer->num_iso_packets
379 * sizeof(struct libusb_iso_packet_descriptor));
384 /* All standard descriptors have these 2 fields in common */
385 struct usb_descriptor_header {
387 uint8_t bDescriptorType;
390 /* shared data and functions */
392 int usbi_io_init(struct libusb_context *ctx);
393 void usbi_io_exit(struct libusb_context *ctx);
395 struct libusb_device *usbi_alloc_device(struct libusb_context *ctx,
396 unsigned long session_id);
397 struct libusb_device *usbi_get_device_by_session_id(struct libusb_context *ctx,
398 unsigned long session_id);
399 int usbi_sanitize_device(struct libusb_device *dev);
400 void usbi_handle_disconnect(struct libusb_device_handle *handle);
402 int usbi_handle_transfer_completion(struct usbi_transfer *itransfer,
403 enum libusb_transfer_status status);
404 int usbi_handle_transfer_cancellation(struct usbi_transfer *transfer);
406 int usbi_parse_descriptor(unsigned char *source, const char *descriptor,
407 void *dest, int host_endian);
408 int usbi_get_config_index_by_value(struct libusb_device *dev,
409 uint8_t bConfigurationValue, int *idx);
414 /* must come first */
415 struct libusb_pollfd pollfd;
417 struct list_head list;
420 int usbi_add_pollfd(struct libusb_context *ctx, int fd, short events);
421 void usbi_remove_pollfd(struct libusb_context *ctx, int fd);
422 void usbi_fd_notification(struct libusb_context *ctx);
424 /* device discovery */
426 /* we traverse usbfs without knowing how many devices we are going to find.
427 * so we create this discovered_devs model which is similar to a linked-list
428 * which grows when required. it can be freed once discovery has completed,
429 * eliminating the need for a list node in the libusb_device structure
431 struct discovered_devs {
434 struct libusb_device *devices[0];
437 struct discovered_devs *discovered_devs_append(
438 struct discovered_devs *discdevs, struct libusb_device *dev);
442 /* This is the interface that OS backends need to implement.
443 * All fields are mandatory, except ones explicitly noted as optional. */
444 struct usbi_os_backend {
445 /* A human-readable name for your backend, e.g. "Linux usbfs" */
448 /* Perform initialization of your backend. You might use this function
449 * to determine specific capabilities of the system, allocate required
450 * data structures for later, etc.
452 * This function is called when a libusbx user initializes the library
455 * Return 0 on success, or a LIBUSB_ERROR code on failure.
457 int (*init)(struct libusb_context *ctx);
459 /* Deinitialization. Optional. This function should destroy anything
460 * that was set up by init.
462 * This function is called when the user deinitializes the library.
466 /* Enumerate all the USB devices on the system, returning them in a list
467 * of discovered devices.
469 * Your implementation should enumerate all devices on the system,
470 * regardless of whether they have been seen before or not.
472 * When you have found a device, compute a session ID for it. The session
473 * ID should uniquely represent that particular device for that particular
474 * connection session since boot (i.e. if you disconnect and reconnect a
475 * device immediately after, it should be assigned a different session ID).
476 * If your OS cannot provide a unique session ID as described above,
477 * presenting a session ID of (bus_number << 8 | device_address) should
478 * be sufficient. Bus numbers and device addresses wrap and get reused,
479 * but that is an unlikely case.
481 * After computing a session ID for a device, call
482 * usbi_get_device_by_session_id(). This function checks if libusbx already
483 * knows about the device, and if so, it provides you with a libusb_device
486 * If usbi_get_device_by_session_id() returns NULL, it is time to allocate
487 * a new device structure for the device. Call usbi_alloc_device() to
488 * obtain a new libusb_device structure with reference count 1. Populate
489 * the bus_number and device_address attributes of the new device, and
490 * perform any other internal backend initialization you need to do. At
491 * this point, you should be ready to provide device descriptors and so
492 * on through the get_*_descriptor functions. Finally, call
493 * usbi_sanitize_device() to perform some final sanity checks on the
494 * device. Assuming all of the above succeeded, we can now continue.
495 * If any of the above failed, remember to unreference the device that
496 * was returned by usbi_alloc_device().
498 * At this stage we have a populated libusb_device structure (either one
499 * that was found earlier, or one that we have just allocated and
500 * populated). This can now be added to the discovered devices list
501 * using discovered_devs_append(). Note that discovered_devs_append()
502 * may reallocate the list, returning a new location for it, and also
503 * note that reallocation can fail. Your backend should handle these
504 * error conditions appropriately.
506 * This function should not generate any bus I/O and should not block.
507 * If I/O is required (e.g. reading the active configuration value), it is
508 * OK to ignore these suggestions :)
510 * This function is executed when the user wishes to retrieve a list
511 * of USB devices connected to the system.
513 * Return 0 on success, or a LIBUSB_ERROR code on failure.
515 int (*get_device_list)(struct libusb_context *ctx,
516 struct discovered_devs **discdevs);
518 /* Open a device for I/O and other USB operations. The device handle
519 * is preallocated for you, you can retrieve the device in question
520 * through handle->dev.
522 * Your backend should allocate any internal resources required for I/O
523 * and other operations so that those operations can happen (hopefully)
524 * without hiccup. This is also a good place to inform libusbx that it
525 * should monitor certain file descriptors related to this device -
526 * see the usbi_add_pollfd() function.
528 * This function should not generate any bus I/O and should not block.
530 * This function is called when the user attempts to obtain a device
531 * handle for a device.
535 * - LIBUSB_ERROR_ACCESS if the user has insufficient permissions
536 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since
538 * - another LIBUSB_ERROR code on other failure
540 * Do not worry about freeing the handle on failed open, the upper layers
543 int (*open)(struct libusb_device_handle *handle);
545 /* Close a device such that the handle cannot be used again. Your backend
546 * should destroy any resources that were allocated in the open path.
547 * This may also be a good place to call usbi_remove_pollfd() to inform
548 * libusbx of any file descriptors associated with this device that should
549 * no longer be monitored.
551 * This function is called when the user closes a device handle.
553 void (*close)(struct libusb_device_handle *handle);
555 /* Retrieve the device descriptor from a device.
557 * The descriptor should be retrieved from memory, NOT via bus I/O to the
558 * device. This means that you may have to cache it in a private structure
559 * during get_device_list enumeration. Alternatively, you may be able
560 * to retrieve it from a kernel interface (some Linux setups can do this)
561 * still without generating bus I/O.
563 * This function is expected to write DEVICE_DESC_LENGTH (18) bytes into
564 * buffer, which is guaranteed to be big enough.
566 * This function is called when sanity-checking a device before adding
567 * it to the list of discovered devices, and also when the user requests
568 * to read the device descriptor.
570 * This function is expected to return the descriptor in bus-endian format
571 * (LE). If it returns the multi-byte values in host-endian format,
572 * set the host_endian output parameter to "1".
574 * Return 0 on success or a LIBUSB_ERROR code on failure.
576 int (*get_device_descriptor)(struct libusb_device *device,
577 unsigned char *buffer, int *host_endian);
579 /* Get the ACTIVE configuration descriptor for a device.
581 * The descriptor should be retrieved from memory, NOT via bus I/O to the
582 * device. This means that you may have to cache it in a private structure
583 * during get_device_list enumeration. You may also have to keep track
584 * of which configuration is active when the user changes it.
586 * This function is expected to write len bytes of data into buffer, which
587 * is guaranteed to be big enough. If you can only do a partial write,
588 * return an error code.
590 * This function is expected to return the descriptor in bus-endian format
591 * (LE). If it returns the multi-byte values in host-endian format,
592 * set the host_endian output parameter to "1".
596 * - LIBUSB_ERROR_NOT_FOUND if the device is in unconfigured state
597 * - another LIBUSB_ERROR code on other failure
599 int (*get_active_config_descriptor)(struct libusb_device *device,
600 unsigned char *buffer, size_t len, int *host_endian);
602 /* Get a specific configuration descriptor for a device.
604 * The descriptor should be retrieved from memory, NOT via bus I/O to the
605 * device. This means that you may have to cache it in a private structure
606 * during get_device_list enumeration.
608 * The requested descriptor is expressed as a zero-based index (i.e. 0
609 * indicates that we are requesting the first descriptor). The index does
610 * not (necessarily) equal the bConfigurationValue of the configuration
613 * This function is expected to write len bytes of data into buffer, which
614 * is guaranteed to be big enough. If you can only do a partial write,
615 * return an error code.
617 * This function is expected to return the descriptor in bus-endian format
618 * (LE). If it returns the multi-byte values in host-endian format,
619 * set the host_endian output parameter to "1".
621 * Return 0 on success or a LIBUSB_ERROR code on failure.
623 int (*get_config_descriptor)(struct libusb_device *device,
624 uint8_t config_index, unsigned char *buffer, size_t len,
627 /* Get the bConfigurationValue for the active configuration for a device.
628 * Optional. This should only be implemented if you can retrieve it from
629 * cache (don't generate I/O).
631 * If you cannot retrieve this from cache, either do not implement this
632 * function, or return LIBUSB_ERROR_NOT_SUPPORTED. This will cause
633 * libusbx to retrieve the information through a standard control transfer.
635 * This function must be non-blocking.
638 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
640 * - LIBUSB_ERROR_NOT_SUPPORTED if the value cannot be retrieved without
642 * - another LIBUSB_ERROR code on other failure.
644 int (*get_configuration)(struct libusb_device_handle *handle, int *config);
646 /* Set the active configuration for a device.
648 * A configuration value of -1 should put the device in unconfigured state.
650 * This function can block.
654 * - LIBUSB_ERROR_NOT_FOUND if the configuration does not exist
655 * - LIBUSB_ERROR_BUSY if interfaces are currently claimed (and hence
656 * configuration cannot be changed)
657 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
659 * - another LIBUSB_ERROR code on other failure.
661 int (*set_configuration)(struct libusb_device_handle *handle, int config);
663 /* Claim an interface. When claimed, the application can then perform
664 * I/O to an interface's endpoints.
666 * This function should not generate any bus I/O and should not block.
667 * Interface claiming is a logical operation that simply ensures that
668 * no other drivers/applications are using the interface, and after
669 * claiming, no other drivers/applicatiosn can use the interface because
674 * - LIBUSB_ERROR_NOT_FOUND if the interface does not exist
675 * - LIBUSB_ERROR_BUSY if the interface is in use by another driver/app
676 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
678 * - another LIBUSB_ERROR code on other failure
680 int (*claim_interface)(struct libusb_device_handle *handle, int interface_number);
682 /* Release a previously claimed interface.
684 * This function should also generate a SET_INTERFACE control request,
685 * resetting the alternate setting of that interface to 0. It's OK for
686 * this function to block as a result.
688 * You will only ever be asked to release an interface which was
689 * successfully claimed earlier.
693 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
695 * - another LIBUSB_ERROR code on other failure
697 int (*release_interface)(struct libusb_device_handle *handle, int interface_number);
699 /* Set the alternate setting for an interface.
701 * You will only ever be asked to set the alternate setting for an
702 * interface which was successfully claimed earlier.
704 * It's OK for this function to block.
708 * - LIBUSB_ERROR_NOT_FOUND if the alternate setting does not exist
709 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
711 * - another LIBUSB_ERROR code on other failure
713 int (*set_interface_altsetting)(struct libusb_device_handle *handle,
714 int interface_number, int altsetting);
716 /* Clear a halt/stall condition on an endpoint.
718 * It's OK for this function to block.
722 * - LIBUSB_ERROR_NOT_FOUND if the endpoint does not exist
723 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
725 * - another LIBUSB_ERROR code on other failure
727 int (*clear_halt)(struct libusb_device_handle *handle,
728 unsigned char endpoint);
730 /* Perform a USB port reset to reinitialize a device.
732 * If possible, the handle should still be usable after the reset
733 * completes, assuming that the device descriptors did not change during
734 * reset and all previous interface state can be restored.
736 * If something changes, or you cannot easily locate/verify the resetted
737 * device, return LIBUSB_ERROR_NOT_FOUND. This prompts the application
738 * to close the old handle and re-enumerate the device.
742 * - LIBUSB_ERROR_NOT_FOUND if re-enumeration is required, or if the device
743 * has been disconnected since it was opened
744 * - another LIBUSB_ERROR code on other failure
746 int (*reset_device)(struct libusb_device_handle *handle);
748 /* Determine if a kernel driver is active on an interface. Optional.
750 * The presence of a kernel driver on an interface indicates that any
751 * calls to claim_interface would fail with the LIBUSB_ERROR_BUSY code.
754 * - 0 if no driver is active
755 * - 1 if a driver is active
756 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
758 * - another LIBUSB_ERROR code on other failure
760 int (*kernel_driver_active)(struct libusb_device_handle *handle,
761 int interface_number);
763 /* Detach a kernel driver from an interface. Optional.
765 * After detaching a kernel driver, the interface should be available
770 * - LIBUSB_ERROR_NOT_FOUND if no kernel driver was active
771 * - LIBUSB_ERROR_INVALID_PARAM if the interface does not exist
772 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
774 * - another LIBUSB_ERROR code on other failure
776 int (*detach_kernel_driver)(struct libusb_device_handle *handle,
777 int interface_number);
779 /* Attach a kernel driver to an interface. Optional.
781 * Reattach a kernel driver to the device.
785 * - LIBUSB_ERROR_NOT_FOUND if no kernel driver was active
786 * - LIBUSB_ERROR_INVALID_PARAM if the interface does not exist
787 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
789 * - LIBUSB_ERROR_BUSY if a program or driver has claimed the interface,
790 * preventing reattachment
791 * - another LIBUSB_ERROR code on other failure
793 int (*attach_kernel_driver)(struct libusb_device_handle *handle,
794 int interface_number);
796 /* Destroy a device. Optional.
798 * This function is called when the last reference to a device is
799 * destroyed. It should free any resources allocated in the get_device_list
802 void (*destroy_device)(struct libusb_device *dev);
804 /* Submit a transfer. Your implementation should take the transfer,
805 * morph it into whatever form your platform requires, and submit it
808 * This function must not block.
812 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
813 * - another LIBUSB_ERROR code on other failure
815 int (*submit_transfer)(struct usbi_transfer *itransfer);
817 /* Cancel a previously submitted transfer.
819 * This function must not block. The transfer cancellation must complete
820 * later, resulting in a call to usbi_handle_transfer_cancellation()
821 * from the context of handle_events.
823 int (*cancel_transfer)(struct usbi_transfer *itransfer);
825 /* Clear a transfer as if it has completed or cancelled, but do not
826 * report any completion/cancellation to the library. You should free
827 * all private data from the transfer as if you were just about to report
828 * completion or cancellation.
830 * This function might seem a bit out of place. It is used when libusbx
831 * detects a disconnected device - it calls this function for all pending
832 * transfers before reporting completion (with the disconnect code) to
833 * the user. Maybe we can improve upon this internal interface in future.
835 void (*clear_transfer_priv)(struct usbi_transfer *itransfer);
837 /* Handle any pending events. This involves monitoring any active
838 * transfers and processing their completion or cancellation.
840 * The function is passed an array of pollfd structures (size nfds)
841 * as a result of the poll() system call. The num_ready parameter
842 * indicates the number of file descriptors that have reported events
843 * (i.e. the poll() return value). This should be enough information
844 * for you to determine which actions need to be taken on the currently
847 * For any cancelled transfers, call usbi_handle_transfer_cancellation().
848 * For completed transfers, call usbi_handle_transfer_completion().
849 * For control/bulk/interrupt transfers, populate the "transferred"
850 * element of the appropriate usbi_transfer structure before calling the
851 * above functions. For isochronous transfers, populate the status and
852 * transferred fields of the iso packet descriptors of the transfer.
854 * This function should also be able to detect disconnection of the
855 * device, reporting that situation with usbi_handle_disconnect().
857 * When processing an event related to a transfer, you probably want to
858 * take usbi_transfer.lock to prevent races. See the documentation for
859 * the usbi_transfer structure.
861 * Return 0 on success, or a LIBUSB_ERROR code on failure.
863 int (*handle_events)(struct libusb_context *ctx,
864 struct pollfd *fds, POLL_NFDS_TYPE nfds, int num_ready);
866 /* Get time from specified clock. At least two clocks must be implemented
867 by the backend: USBI_CLOCK_REALTIME, and USBI_CLOCK_MONOTONIC.
869 Description of clocks:
870 USBI_CLOCK_REALTIME : clock returns time since system epoch.
871 USBI_CLOCK_MONOTONIC: clock returns time since unspecified start
874 int (*clock_gettime)(int clkid, struct timespec *tp);
876 #ifdef USBI_TIMERFD_AVAILABLE
877 /* clock ID of the clock that should be used for timerfd */
878 clockid_t (*get_timerfd_clockid)(void);
881 /* Number of bytes to reserve for per-device private backend data.
882 * This private data area is accessible through the "os_priv" field of
883 * struct libusb_device. */
884 size_t device_priv_size;
886 /* Number of bytes to reserve for per-handle private backend data.
887 * This private data area is accessible through the "os_priv" field of
888 * struct libusb_device. */
889 size_t device_handle_priv_size;
891 /* Number of bytes to reserve for per-transfer private backend data.
892 * This private data area is accessible by calling
893 * usbi_transfer_get_os_priv() on the appropriate usbi_transfer instance.
895 size_t transfer_priv_size;
897 /* Mumber of additional bytes for os_priv for each iso packet.
898 * Can your backend use this? */
899 /* FIXME: linux can't use this any more. if other OS's cannot either,
900 * then remove this */
901 size_t add_iso_packet_size;
904 extern const struct usbi_os_backend * const usbi_backend;
906 extern const struct usbi_os_backend linux_usbfs_backend;
907 extern const struct usbi_os_backend darwin_backend;
908 extern const struct usbi_os_backend openbsd_backend;
909 extern const struct usbi_os_backend windows_backend;