2 * Internal header for libusb
3 * Copyright (C) 2007-2009 Daniel Drake <dsd@gentoo.org>
4 * Copyright (c) 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
32 /* Inside the libusb code, mark all public functions as follows:
33 * return_type API_EXPORTED function_name(params) { ... }
34 * But if the function returns a pointer, mark it as follows:
35 * DEFAULT_VISIBILITY return_type * LIBUSB_CALL function_name(params) { ... }
36 * In the libusb public header, mark all declarations as:
37 * return_type LIBUSB_CALL function_name(params);
39 #define API_EXPORTED LIBUSB_CALL DEFAULT_VISIBILITY
41 #define DEVICE_DESC_LENGTH 18
43 #define USB_MAXENDPOINTS 32
44 #define USB_MAXINTERFACES 32
45 #define USB_MAXCONFIG 8
48 struct list_head *prev, *next;
51 /* Get an entry from the list
52 * ptr - the address of this list_head element in "type"
53 * type - the data type that contains "member"
54 * member - the list_head element in "type"
56 #define list_entry(ptr, type, member) \
57 ((type *)((uintptr_t)(ptr) - (uintptr_t)(&((type *)0L)->member)))
59 /* Get each entry from a list
60 * pos - A structure pointer has a "member" element
62 * member - the list_head element in "pos"
63 * type - the type of the first parameter
65 #define list_for_each_entry(pos, head, member, type) \
66 for (pos = list_entry((head)->next, type, member); \
67 &pos->member != (head); \
68 pos = list_entry(pos->member.next, type, member))
70 #define list_for_each_entry_safe(pos, n, head, member, type) \
71 for (pos = list_entry((head)->next, type, member), \
72 n = list_entry(pos->member.next, type, member); \
73 &pos->member != (head); \
74 pos = n, n = list_entry(n->member.next, type, member))
76 #define list_empty(entry) ((entry)->next == (entry))
78 static inline void list_init(struct list_head *entry)
80 entry->prev = entry->next = entry;
83 static inline void list_add(struct list_head *entry, struct list_head *head)
85 entry->next = head->next;
88 head->next->prev = entry;
92 static inline void list_add_tail(struct list_head *entry,
93 struct list_head *head)
96 entry->prev = head->prev;
98 head->prev->next = entry;
102 static inline void list_del(struct list_head *entry)
104 entry->next->prev = entry->prev;
105 entry->prev->next = entry->next;
108 #define container_of(ptr, type, member) ({ \
109 const typeof( ((type *)0)->member ) *__mptr = (ptr); \
110 (type *)( (char *)__mptr - offsetof(type,member) );})
112 #define MIN(a, b) ((a) < (b) ? (a) : (b))
113 #define MAX(a, b) ((a) > (b) ? (a) : (b))
115 #define TIMESPEC_IS_SET(ts) ((ts)->tv_sec != 0 || (ts)->tv_nsec != 0)
117 enum usbi_log_level {
124 void usbi_log(struct libusb_context *ctx, enum usbi_log_level level,
125 const char *function, const char *format, ...);
127 #if !defined(_MSC_VER) || _MSC_VER > 1200
129 #ifdef ENABLE_LOGGING
130 #define _usbi_log(ctx, level, ...) usbi_log(ctx, level, __FUNCTION__, __VA_ARGS__)
132 #define _usbi_log(ctx, level, ...) do {} while(0)
135 #ifdef ENABLE_DEBUG_LOGGING
136 #define usbi_dbg(...) _usbi_log(NULL, LOG_LEVEL_DEBUG, __VA_ARGS__)
138 #define usbi_dbg(...) do {} while(0)
141 #define usbi_info(ctx, ...) _usbi_log(ctx, LOG_LEVEL_INFO, __VA_ARGS__)
142 #define usbi_warn(ctx, ...) _usbi_log(ctx, LOG_LEVEL_WARNING, __VA_ARGS__)
143 #define usbi_err(ctx, ...) _usbi_log(ctx, LOG_LEVEL_ERROR, __VA_ARGS__)
145 #else /* !defined(_MSC_VER) || _MSC_VER > 1200 */
147 void usbi_log_v(struct libusb_context *ctx, enum usbi_log_level level,
148 const char *function, const char *format, va_list args);
150 #ifdef ENABLE_LOGGING
151 #define LOG_BODY(ctxt, level) \
154 va_start (args, format); \
155 usbi_log_v(ctxt, level, "", format, args); \
159 #define LOG_BODY(ctxt, level) { }
162 static inline void usbi_info(struct libusb_context *ctx, const char *format,
164 LOG_BODY(ctx,LOG_LEVEL_INFO)
165 static inline void usbi_warn(struct libusb_context *ctx, const char *format,
167 LOG_BODY(ctx,LOG_LEVEL_WARNING)
168 static inline void usbi_err( struct libusb_context *ctx, const char *format,
170 LOG_BODY(ctx,LOG_LEVEL_ERROR)
172 static inline void usbi_dbg(const char *format, ...)
173 #ifdef ENABLE_DEBUG_LOGGING
174 LOG_BODY(NULL,LOG_LEVEL_DEBUG)
179 #endif /* !defined(_MSC_VER) || _MSC_VER > 1200 */
181 #define USBI_GET_CONTEXT(ctx) if (!(ctx)) (ctx) = usbi_default_context
182 #define DEVICE_CTX(dev) ((dev)->ctx)
183 #define HANDLE_CTX(handle) (DEVICE_CTX((handle)->dev))
184 #define TRANSFER_CTX(transfer) (HANDLE_CTX((transfer)->dev_handle))
185 #define ITRANSFER_CTX(transfer) \
186 (TRANSFER_CTX(__USBI_TRANSFER_TO_LIBUSB_TRANSFER(transfer)))
188 /* Internal abstractions for thread synchronization and poll */
189 #if defined(THREADS_POSIX)
190 #include <os/threads_posix.h>
191 #elif defined(OS_WINDOWS)
192 #include <os/threads_windows.h>
195 #if defined(OS_LINUX) || defined(OS_DARWIN)
196 #include <os/poll_posix.h>
197 #elif defined(OS_WINDOWS)
198 #include <os/poll_windows.h>
201 extern struct libusb_context *usbi_default_context;
203 struct libusb_context {
207 /* internal control pipe, used for interrupting event handling when
208 * something needs to modify poll fds. */
211 struct list_head usb_devs;
212 usbi_mutex_t usb_devs_lock;
214 /* A list of open handles. Backends are free to traverse this if required.
216 struct list_head open_devs;
217 usbi_mutex_t open_devs_lock;
219 /* this is a list of in-flight transfer handles, sorted by timeout
220 * expiration. URBs to timeout the soonest are placed at the beginning of
221 * the list, URBs that will time out later are placed after, and urbs with
222 * infinite timeout are always placed at the very end. */
223 struct list_head flying_transfers;
224 usbi_mutex_t flying_transfers_lock;
226 /* list of poll fds */
227 struct list_head pollfds;
228 usbi_mutex_t pollfds_lock;
230 /* a counter that is set when we want to interrupt event handling, in order
231 * to modify the poll fd set. and a lock to protect it. */
232 unsigned int pollfd_modify;
233 usbi_mutex_t pollfd_modify_lock;
235 /* user callbacks for pollfd changes */
236 libusb_pollfd_added_cb fd_added_cb;
237 libusb_pollfd_removed_cb fd_removed_cb;
238 void *fd_cb_user_data;
240 /* ensures that only one thread is handling events at any one time */
241 usbi_mutex_t events_lock;
243 /* used to see if there is an active thread doing event handling */
244 int event_handler_active;
246 /* used to wait for event completion in threads other than the one that is
248 usbi_mutex_t event_waiters_lock;
249 usbi_cond_t event_waiters_cond;
251 #ifdef USBI_TIMERFD_AVAILABLE
252 /* used for timeout handling, if supported by OS.
253 * this timerfd is maintained to trigger on the next pending timeout */
258 #ifdef USBI_TIMERFD_AVAILABLE
259 #define usbi_using_timerfd(ctx) ((ctx)->timerfd >= 0)
261 #define usbi_using_timerfd(ctx) (0)
264 struct libusb_device {
265 /* lock protects refcnt, everything else is finalized at initialization
270 struct libusb_context *ctx;
273 uint8_t device_address;
274 uint8_t num_configurations;
276 struct list_head list;
277 unsigned long session_data;
278 unsigned char os_priv[0];
281 struct libusb_device_handle {
282 /* lock protects claimed_interfaces */
284 unsigned long claimed_interfaces;
286 struct list_head list;
287 struct libusb_device *dev;
288 unsigned char os_priv[0];
292 USBI_CLOCK_MONOTONIC,
296 /* in-memory transfer layout:
298 * 1. struct usbi_transfer
299 * 2. struct libusb_transfer (which includes iso packets) [variable size]
300 * 3. os private data [variable size]
302 * from a libusb_transfer, you can get the usbi_transfer by rewinding the
303 * appropriate number of bytes.
304 * the usbi_transfer includes the number of allocated packets, so you can
305 * determine the size of the transfer and hence the start and length of the
309 struct usbi_transfer {
311 struct list_head list;
312 struct timeval timeout;
316 /* this lock is held during libusb_submit_transfer() and
317 * libusb_cancel_transfer() (allowing the OS backend to prevent duplicate
318 * cancellation, submission-during-cancellation, etc). the OS backend
319 * should also take this lock in the handle_events path, to prevent the user
320 * cancelling the transfer from another thread while you are processing
321 * its completion (presumably there would be races within your OS backend
322 * if this were possible). */
326 enum usbi_transfer_flags {
327 /* The transfer has timed out */
328 USBI_TRANSFER_TIMED_OUT = 1 << 0,
330 /* Set by backend submit_transfer() if the OS handles timeout */
331 USBI_TRANSFER_OS_HANDLES_TIMEOUT = 1 << 1
334 #define __USBI_TRANSFER_TO_LIBUSB_TRANSFER(transfer) \
335 ((struct libusb_transfer *)(((unsigned char *)(transfer)) \
336 + sizeof(struct usbi_transfer)))
337 #define __LIBUSB_TRANSFER_TO_USBI_TRANSFER(transfer) \
338 ((struct usbi_transfer *)(((unsigned char *)(transfer)) \
339 - sizeof(struct usbi_transfer)))
341 static inline void *usbi_transfer_get_os_priv(struct usbi_transfer *transfer)
343 return ((unsigned char *)transfer) + sizeof(struct usbi_transfer)
344 + sizeof(struct libusb_transfer)
345 + (transfer->num_iso_packets
346 * sizeof(struct libusb_iso_packet_descriptor));
351 /* All standard descriptors have these 2 fields in common */
352 struct usb_descriptor_header {
354 uint8_t bDescriptorType;
357 /* shared data and functions */
359 int usbi_io_init(struct libusb_context *ctx);
360 void usbi_io_exit(struct libusb_context *ctx);
362 struct libusb_device *usbi_alloc_device(struct libusb_context *ctx,
363 unsigned long session_id);
364 struct libusb_device *usbi_get_device_by_session_id(struct libusb_context *ctx,
365 unsigned long session_id);
366 int usbi_sanitize_device(struct libusb_device *dev);
367 void usbi_handle_disconnect(struct libusb_device_handle *handle);
369 int usbi_handle_transfer_completion(struct usbi_transfer *itransfer,
370 enum libusb_transfer_status status);
371 int usbi_handle_transfer_cancellation(struct usbi_transfer *transfer);
373 int usbi_parse_descriptor(unsigned char *source, const char *descriptor,
374 void *dest, int host_endian);
375 int usbi_get_config_index_by_value(struct libusb_device *dev,
376 uint8_t bConfigurationValue, int *idx);
381 /* must come first */
382 struct libusb_pollfd pollfd;
384 struct list_head list;
387 int usbi_add_pollfd(struct libusb_context *ctx, int fd, short events);
388 void usbi_remove_pollfd(struct libusb_context *ctx, int fd);
389 void usbi_fd_notification(struct libusb_context *ctx);
391 /* device discovery */
393 /* we traverse usbfs without knowing how many devices we are going to find.
394 * so we create this discovered_devs model which is similar to a linked-list
395 * which grows when required. it can be freed once discovery has completed,
396 * eliminating the need for a list node in the libusb_device structure
398 struct discovered_devs {
401 struct libusb_device *devices[0];
404 struct discovered_devs *discovered_devs_append(
405 struct discovered_devs *discdevs, struct libusb_device *dev);
409 /* This is the interface that OS backends need to implement.
410 * All fields are mandatory, except ones explicitly noted as optional. */
411 struct usbi_os_backend {
412 /* A human-readable name for your backend, e.g. "Linux usbfs" */
415 /* Perform initialization of your backend. You might use this function
416 * to determine specific capabilities of the system, allocate required
417 * data structures for later, etc.
419 * This function is called when a libusb user initializes the library
422 * Return 0 on success, or a LIBUSB_ERROR code on failure.
424 int (*init)(struct libusb_context *ctx);
426 /* Deinitialization. Optional. This function should destroy anything
427 * that was set up by init.
429 * This function is called when the user deinitializes the library.
433 /* Enumerate all the USB devices on the system, returning them in a list
434 * of discovered devices.
436 * Your implementation should enumerate all devices on the system,
437 * regardless of whether they have been seen before or not.
439 * When you have found a device, compute a session ID for it. The session
440 * ID should uniquely represent that particular device for that particular
441 * connection session since boot (i.e. if you disconnect and reconnect a
442 * device immediately after, it should be assigned a different session ID).
443 * If your OS cannot provide a unique session ID as described above,
444 * presenting a session ID of (bus_number << 8 | device_address) should
445 * be sufficient. Bus numbers and device addresses wrap and get reused,
446 * but that is an unlikely case.
448 * After computing a session ID for a device, call
449 * usbi_get_device_by_session_id(). This function checks if libusb already
450 * knows about the device, and if so, it provides you with a libusb_device
453 * If usbi_get_device_by_session_id() returns NULL, it is time to allocate
454 * a new device structure for the device. Call usbi_alloc_device() to
455 * obtain a new libusb_device structure with reference count 1. Populate
456 * the bus_number and device_address attributes of the new device, and
457 * perform any other internal backend initialization you need to do. At
458 * this point, you should be ready to provide device descriptors and so
459 * on through the get_*_descriptor functions. Finally, call
460 * usbi_sanitize_device() to perform some final sanity checks on the
461 * device. Assuming all of the above succeeded, we can now continue.
462 * If any of the above failed, remember to unreference the device that
463 * was returned by usbi_alloc_device().
465 * At this stage we have a populated libusb_device structure (either one
466 * that was found earlier, or one that we have just allocated and
467 * populated). This can now be added to the discovered devices list
468 * using discovered_devs_append(). Note that discovered_devs_append()
469 * may reallocate the list, returning a new location for it, and also
470 * note that reallocation can fail. Your backend should handle these
471 * error conditions appropriately.
473 * This function should not generate any bus I/O and should not block.
474 * If I/O is required (e.g. reading the active configuration value), it is
475 * OK to ignore these suggestions :)
477 * This function is executed when the user wishes to retrieve a list
478 * of USB devices connected to the system.
480 * Return 0 on success, or a LIBUSB_ERROR code on failure.
482 int (*get_device_list)(struct libusb_context *ctx,
483 struct discovered_devs **discdevs);
485 /* Open a device for I/O and other USB operations. The device handle
486 * is preallocated for you, you can retrieve the device in question
487 * through handle->dev.
489 * Your backend should allocate any internal resources required for I/O
490 * and other operations so that those operations can happen (hopefully)
491 * without hiccup. This is also a good place to inform libusb that it
492 * should monitor certain file descriptors related to this device -
493 * see the usbi_add_pollfd() function.
495 * This function should not generate any bus I/O and should not block.
497 * This function is called when the user attempts to obtain a device
498 * handle for a device.
502 * - LIBUSB_ERROR_ACCESS if the user has insufficient permissions
503 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since
505 * - another LIBUSB_ERROR code on other failure
507 * Do not worry about freeing the handle on failed open, the upper layers
510 int (*open)(struct libusb_device_handle *handle);
512 /* Close a device such that the handle cannot be used again. Your backend
513 * should destroy any resources that were allocated in the open path.
514 * This may also be a good place to call usbi_remove_pollfd() to inform
515 * libusb of any file descriptors associated with this device that should
516 * no longer be monitored.
518 * This function is called when the user closes a device handle.
520 void (*close)(struct libusb_device_handle *handle);
522 /* Retrieve the device descriptor from a device.
524 * The descriptor should be retrieved from memory, NOT via bus I/O to the
525 * device. This means that you may have to cache it in a private structure
526 * during get_device_list enumeration. Alternatively, you may be able
527 * to retrieve it from a kernel interface (some Linux setups can do this)
528 * still without generating bus I/O.
530 * This function is expected to write DEVICE_DESC_LENGTH (18) bytes into
531 * buffer, which is guaranteed to be big enough.
533 * This function is called when sanity-checking a device before adding
534 * it to the list of discovered devices, and also when the user requests
535 * to read the device descriptor.
537 * This function is expected to return the descriptor in bus-endian format
538 * (LE). If it returns the multi-byte values in host-endian format,
539 * set the host_endian output parameter to "1".
541 * Return 0 on success or a LIBUSB_ERROR code on failure.
543 int (*get_device_descriptor)(struct libusb_device *device,
544 unsigned char *buffer, int *host_endian);
546 /* Get the ACTIVE configuration descriptor for a device.
548 * The descriptor should be retrieved from memory, NOT via bus I/O to the
549 * device. This means that you may have to cache it in a private structure
550 * during get_device_list enumeration. You may also have to keep track
551 * of which configuration is active when the user changes it.
553 * This function is expected to write len bytes of data into buffer, which
554 * is guaranteed to be big enough. If you can only do a partial write,
555 * return an error code.
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".
563 * - LIBUSB_ERROR_NOT_FOUND if the device is in unconfigured state
564 * - another LIBUSB_ERROR code on other failure
566 int (*get_active_config_descriptor)(struct libusb_device *device,
567 unsigned char *buffer, size_t len, int *host_endian);
569 /* Get a specific configuration descriptor for a device.
571 * The descriptor should be retrieved from memory, NOT via bus I/O to the
572 * device. This means that you may have to cache it in a private structure
573 * during get_device_list enumeration.
575 * The requested descriptor is expressed as a zero-based index (i.e. 0
576 * indicates that we are requesting the first descriptor). The index does
577 * not (necessarily) equal the bConfigurationValue of the configuration
580 * This function is expected to write len bytes of data into buffer, which
581 * is guaranteed to be big enough. If you can only do a partial write,
582 * return an error code.
584 * This function is expected to return the descriptor in bus-endian format
585 * (LE). If it returns the multi-byte values in host-endian format,
586 * set the host_endian output parameter to "1".
588 * Return 0 on success or a LIBUSB_ERROR code on failure.
590 int (*get_config_descriptor)(struct libusb_device *device,
591 uint8_t config_index, unsigned char *buffer, size_t len,
594 /* Get the bConfigurationValue for the active configuration for a device.
595 * Optional. This should only be implemented if you can retrieve it from
596 * cache (don't generate I/O).
598 * If you cannot retrieve this from cache, either do not implement this
599 * function, or return LIBUSB_ERROR_NOT_SUPPORTED. This will cause
600 * libusb to retrieve the information through a standard control transfer.
602 * This function must be non-blocking.
605 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
607 * - LIBUSB_ERROR_NOT_SUPPORTED if the value cannot be retrieved without
609 * - another LIBUSB_ERROR code on other failure.
611 int (*get_configuration)(struct libusb_device_handle *handle, int *config);
613 /* Set the active configuration for a device.
615 * A configuration value of -1 should put the device in unconfigured state.
617 * This function can block.
621 * - LIBUSB_ERROR_NOT_FOUND if the configuration does not exist
622 * - LIBUSB_ERROR_BUSY if interfaces are currently claimed (and hence
623 * configuration cannot be changed)
624 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
626 * - another LIBUSB_ERROR code on other failure.
628 int (*set_configuration)(struct libusb_device_handle *handle, int config);
630 /* Claim an interface. When claimed, the application can then perform
631 * I/O to an interface's endpoints.
633 * This function should not generate any bus I/O and should not block.
634 * Interface claiming is a logical operation that simply ensures that
635 * no other drivers/applications are using the interface, and after
636 * claiming, no other drivers/applicatiosn can use the interface because
641 * - LIBUSB_ERROR_NOT_FOUND if the interface does not exist
642 * - LIBUSB_ERROR_BUSY if the interface is in use by another driver/app
643 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
645 * - another LIBUSB_ERROR code on other failure
647 int (*claim_interface)(struct libusb_device_handle *handle, int interface_number);
649 /* Release a previously claimed interface.
651 * This function should also generate a SET_INTERFACE control request,
652 * resetting the alternate setting of that interface to 0. It's OK for
653 * this function to block as a result.
655 * You will only ever be asked to release an interface which was
656 * successfully claimed earlier.
660 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
662 * - another LIBUSB_ERROR code on other failure
664 int (*release_interface)(struct libusb_device_handle *handle, int interface_number);
666 /* Set the alternate setting for an interface.
668 * You will only ever be asked to set the alternate setting for an
669 * interface which was successfully claimed earlier.
671 * It's OK for this function to block.
675 * - LIBUSB_ERROR_NOT_FOUND if the alternate setting does not exist
676 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
678 * - another LIBUSB_ERROR code on other failure
680 int (*set_interface_altsetting)(struct libusb_device_handle *handle,
681 int interface_number, int altsetting);
683 /* Clear a halt/stall condition on an endpoint.
685 * It's OK for this function to block.
689 * - LIBUSB_ERROR_NOT_FOUND if the endpoint does not exist
690 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
692 * - another LIBUSB_ERROR code on other failure
694 int (*clear_halt)(struct libusb_device_handle *handle,
695 unsigned char endpoint);
697 /* Perform a USB port reset to reinitialize a device.
699 * If possible, the handle should still be usable after the reset
700 * completes, assuming that the device descriptors did not change during
701 * reset and all previous interface state can be restored.
703 * If something changes, or you cannot easily locate/verify the resetted
704 * device, return LIBUSB_ERROR_NOT_FOUND. This prompts the application
705 * to close the old handle and re-enumerate the device.
709 * - LIBUSB_ERROR_NOT_FOUND if re-enumeration is required, or if the device
710 * has been disconnected since it was opened
711 * - another LIBUSB_ERROR code on other failure
713 int (*reset_device)(struct libusb_device_handle *handle);
715 /* Determine if a kernel driver is active on an interface. Optional.
717 * The presence of a kernel driver on an interface indicates that any
718 * calls to claim_interface would fail with the LIBUSB_ERROR_BUSY code.
721 * - 0 if no driver is active
722 * - 1 if a driver is active
723 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
725 * - another LIBUSB_ERROR code on other failure
727 int (*kernel_driver_active)(struct libusb_device_handle *handle,
728 int interface_number);
730 /* Detach a kernel driver from an interface. Optional.
732 * After detaching a kernel driver, the interface should be available
737 * - LIBUSB_ERROR_NOT_FOUND if no kernel driver was active
738 * - LIBUSB_ERROR_INVALID_PARAM if the interface does not exist
739 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
741 * - another LIBUSB_ERROR code on other failure
743 int (*detach_kernel_driver)(struct libusb_device_handle *handle,
744 int interface_number);
746 /* Attach a kernel driver to an interface. Optional.
748 * Reattach a kernel driver to the device.
752 * - LIBUSB_ERROR_NOT_FOUND if no kernel driver was active
753 * - LIBUSB_ERROR_INVALID_PARAM if the interface does not exist
754 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
756 * - LIBUSB_ERROR_BUSY if a program or driver has claimed the interface,
757 * preventing reattachment
758 * - another LIBUSB_ERROR code on other failure
760 int (*attach_kernel_driver)(struct libusb_device_handle *handle,
761 int interface_number);
763 /* Destroy a device. Optional.
765 * This function is called when the last reference to a device is
766 * destroyed. It should free any resources allocated in the get_device_list
769 void (*destroy_device)(struct libusb_device *dev);
771 /* Submit a transfer. Your implementation should take the transfer,
772 * morph it into whatever form your platform requires, and submit it
775 * This function must not block.
779 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
780 * - another LIBUSB_ERROR code on other failure
782 int (*submit_transfer)(struct usbi_transfer *itransfer);
784 /* Cancel a previously submitted transfer.
786 * This function must not block. The transfer cancellation must complete
787 * later, resulting in a call to usbi_handle_transfer_cancellation()
788 * from the context of handle_events.
790 int (*cancel_transfer)(struct usbi_transfer *itransfer);
792 /* Clear a transfer as if it has completed or cancelled, but do not
793 * report any completion/cancellation to the library. You should free
794 * all private data from the transfer as if you were just about to report
795 * completion or cancellation.
797 * This function might seem a bit out of place. It is used when libusb
798 * detects a disconnected device - it calls this function for all pending
799 * transfers before reporting completion (with the disconnect code) to
800 * the user. Maybe we can improve upon this internal interface in future.
802 void (*clear_transfer_priv)(struct usbi_transfer *itransfer);
804 /* Handle any pending events. This involves monitoring any active
805 * transfers and processing their completion or cancellation.
807 * The function is passed an array of pollfd structures (size nfds)
808 * as a result of the poll() system call. The num_ready parameter
809 * indicates the number of file descriptors that have reported events
810 * (i.e. the poll() return value). This should be enough information
811 * for you to determine which actions need to be taken on the currently
814 * For any cancelled transfers, call usbi_handle_transfer_cancellation().
815 * For completed transfers, call usbi_handle_transfer_completion().
816 * For control/bulk/interrupt transfers, populate the "transferred"
817 * element of the appropriate usbi_transfer structure before calling the
818 * above functions. For isochronous transfers, populate the status and
819 * transferred fields of the iso packet descriptors of the transfer.
821 * This function should also be able to detect disconnection of the
822 * device, reporting that situation with usbi_handle_disconnect().
824 * When processing an event related to a transfer, you probably want to
825 * take usbi_transfer.lock to prevent races. See the documentation for
826 * the usbi_transfer structure.
828 * Return 0 on success, or a LIBUSB_ERROR code on failure.
830 int (*handle_events)(struct libusb_context *ctx,
831 struct pollfd *fds, nfds_t nfds, int num_ready);
833 /* Get time from specified clock. At least two clocks must be implemented
834 by the backend: USBI_CLOCK_REALTIME, and USBI_CLOCK_MONOTONIC.
836 Description of clocks:
837 USBI_CLOCK_REALTIME : clock returns time since system epoch.
838 USBI_CLOCK_MONOTONIC: clock returns time since unspecified start
841 int (*clock_gettime)(int clkid, struct timespec *tp);
843 #ifdef USBI_TIMERFD_AVAILABLE
844 /* clock ID of the clock that should be used for timerfd */
845 clockid_t (*get_timerfd_clockid)(void);
848 /* Number of bytes to reserve for per-device private backend data.
849 * This private data area is accessible through the "os_priv" field of
850 * struct libusb_device. */
851 size_t device_priv_size;
853 /* Number of bytes to reserve for per-handle private backend data.
854 * This private data area is accessible through the "os_priv" field of
855 * struct libusb_device. */
856 size_t device_handle_priv_size;
858 /* Number of bytes to reserve for per-transfer private backend data.
859 * This private data area is accessible by calling
860 * usbi_transfer_get_os_priv() on the appropriate usbi_transfer instance.
862 size_t transfer_priv_size;
864 /* Mumber of additional bytes for os_priv for each iso packet.
865 * Can your backend use this? */
866 /* FIXME: linux can't use this any more. if other OS's cannot either,
867 * then remove this */
868 size_t add_iso_packet_size;
871 extern const struct usbi_os_backend * const usbi_backend;
873 extern const struct usbi_os_backend linux_usbfs_backend;
874 extern const struct usbi_os_backend darwin_backend;
875 extern const struct usbi_os_backend windows_backend;