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;
297 struct libusb_device* parent_dev;
298 uint8_t device_address;
299 uint8_t num_configurations;
300 enum libusb_speed speed;
302 struct list_head list;
303 unsigned long session_data;
304 unsigned char os_priv[0];
307 struct libusb_device_handle {
308 /* lock protects claimed_interfaces */
310 unsigned long claimed_interfaces;
312 struct list_head list;
313 struct libusb_device *dev;
314 unsigned char os_priv[0];
318 USBI_CLOCK_MONOTONIC,
322 /* in-memory transfer layout:
324 * 1. struct usbi_transfer
325 * 2. struct libusb_transfer (which includes iso packets) [variable size]
326 * 3. os private data [variable size]
328 * from a libusb_transfer, you can get the usbi_transfer by rewinding the
329 * appropriate number of bytes.
330 * the usbi_transfer includes the number of allocated packets, so you can
331 * determine the size of the transfer and hence the start and length of the
335 struct usbi_transfer {
337 struct list_head list;
338 struct timeval timeout;
342 /* this lock is held during libusb_submit_transfer() and
343 * libusb_cancel_transfer() (allowing the OS backend to prevent duplicate
344 * cancellation, submission-during-cancellation, etc). the OS backend
345 * should also take this lock in the handle_events path, to prevent the user
346 * cancelling the transfer from another thread while you are processing
347 * its completion (presumably there would be races within your OS backend
348 * if this were possible). */
352 enum usbi_transfer_flags {
353 /* The transfer has timed out */
354 USBI_TRANSFER_TIMED_OUT = 1 << 0,
356 /* Set by backend submit_transfer() if the OS handles timeout */
357 USBI_TRANSFER_OS_HANDLES_TIMEOUT = 1 << 1,
359 /* Cancellation was requested via libusb_cancel_transfer() */
360 USBI_TRANSFER_CANCELLING = 1 << 2,
362 /* Operation on the transfer failed because the device disappeared */
363 USBI_TRANSFER_DEVICE_DISAPPEARED = 1 << 3,
365 /* Set by backend submit_transfer() if the fds in use have been updated */
366 USBI_TRANSFER_UPDATED_FDS = 1 << 4,
369 #define USBI_TRANSFER_TO_LIBUSB_TRANSFER(transfer) \
370 ((struct libusb_transfer *)(((unsigned char *)(transfer)) \
371 + sizeof(struct usbi_transfer)))
372 #define LIBUSB_TRANSFER_TO_USBI_TRANSFER(transfer) \
373 ((struct usbi_transfer *)(((unsigned char *)(transfer)) \
374 - sizeof(struct usbi_transfer)))
376 static inline void *usbi_transfer_get_os_priv(struct usbi_transfer *transfer)
378 return ((unsigned char *)transfer) + sizeof(struct usbi_transfer)
379 + sizeof(struct libusb_transfer)
380 + (transfer->num_iso_packets
381 * sizeof(struct libusb_iso_packet_descriptor));
386 /* All standard descriptors have these 2 fields in common */
387 struct usb_descriptor_header {
389 uint8_t bDescriptorType;
392 /* shared data and functions */
394 int usbi_io_init(struct libusb_context *ctx);
395 void usbi_io_exit(struct libusb_context *ctx);
397 struct libusb_device *usbi_alloc_device(struct libusb_context *ctx,
398 unsigned long session_id);
399 struct libusb_device *usbi_get_device_by_session_id(struct libusb_context *ctx,
400 unsigned long session_id);
401 int usbi_sanitize_device(struct libusb_device *dev);
402 void usbi_handle_disconnect(struct libusb_device_handle *handle);
404 int usbi_handle_transfer_completion(struct usbi_transfer *itransfer,
405 enum libusb_transfer_status status);
406 int usbi_handle_transfer_cancellation(struct usbi_transfer *transfer);
408 int usbi_parse_descriptor(unsigned char *source, const char *descriptor,
409 void *dest, int host_endian);
410 int usbi_get_config_index_by_value(struct libusb_device *dev,
411 uint8_t bConfigurationValue, int *idx);
416 /* must come first */
417 struct libusb_pollfd pollfd;
419 struct list_head list;
422 int usbi_add_pollfd(struct libusb_context *ctx, int fd, short events);
423 void usbi_remove_pollfd(struct libusb_context *ctx, int fd);
424 void usbi_fd_notification(struct libusb_context *ctx);
426 /* device discovery */
428 /* we traverse usbfs without knowing how many devices we are going to find.
429 * so we create this discovered_devs model which is similar to a linked-list
430 * which grows when required. it can be freed once discovery has completed,
431 * eliminating the need for a list node in the libusb_device structure
433 struct discovered_devs {
436 struct libusb_device *devices[0];
439 struct discovered_devs *discovered_devs_append(
440 struct discovered_devs *discdevs, struct libusb_device *dev);
444 /* This is the interface that OS backends need to implement.
445 * All fields are mandatory, except ones explicitly noted as optional. */
446 struct usbi_os_backend {
447 /* A human-readable name for your backend, e.g. "Linux usbfs" */
450 /* Perform initialization of your backend. You might use this function
451 * to determine specific capabilities of the system, allocate required
452 * data structures for later, etc.
454 * This function is called when a libusbx user initializes the library
457 * Return 0 on success, or a LIBUSB_ERROR code on failure.
459 int (*init)(struct libusb_context *ctx);
461 /* Deinitialization. Optional. This function should destroy anything
462 * that was set up by init.
464 * This function is called when the user deinitializes the library.
468 /* Enumerate all the USB devices on the system, returning them in a list
469 * of discovered devices.
471 * Your implementation should enumerate all devices on the system,
472 * regardless of whether they have been seen before or not.
474 * When you have found a device, compute a session ID for it. The session
475 * ID should uniquely represent that particular device for that particular
476 * connection session since boot (i.e. if you disconnect and reconnect a
477 * device immediately after, it should be assigned a different session ID).
478 * If your OS cannot provide a unique session ID as described above,
479 * presenting a session ID of (bus_number << 8 | device_address) should
480 * be sufficient. Bus numbers and device addresses wrap and get reused,
481 * but that is an unlikely case.
483 * After computing a session ID for a device, call
484 * usbi_get_device_by_session_id(). This function checks if libusbx already
485 * knows about the device, and if so, it provides you with a libusb_device
488 * If usbi_get_device_by_session_id() returns NULL, it is time to allocate
489 * a new device structure for the device. Call usbi_alloc_device() to
490 * obtain a new libusb_device structure with reference count 1. Populate
491 * the bus_number and device_address attributes of the new device, and
492 * perform any other internal backend initialization you need to do. At
493 * this point, you should be ready to provide device descriptors and so
494 * on through the get_*_descriptor functions. Finally, call
495 * usbi_sanitize_device() to perform some final sanity checks on the
496 * device. Assuming all of the above succeeded, we can now continue.
497 * If any of the above failed, remember to unreference the device that
498 * was returned by usbi_alloc_device().
500 * At this stage we have a populated libusb_device structure (either one
501 * that was found earlier, or one that we have just allocated and
502 * populated). This can now be added to the discovered devices list
503 * using discovered_devs_append(). Note that discovered_devs_append()
504 * may reallocate the list, returning a new location for it, and also
505 * note that reallocation can fail. Your backend should handle these
506 * error conditions appropriately.
508 * This function should not generate any bus I/O and should not block.
509 * If I/O is required (e.g. reading the active configuration value), it is
510 * OK to ignore these suggestions :)
512 * This function is executed when the user wishes to retrieve a list
513 * of USB devices connected to the system.
515 * Return 0 on success, or a LIBUSB_ERROR code on failure.
517 int (*get_device_list)(struct libusb_context *ctx,
518 struct discovered_devs **discdevs);
520 /* Open a device for I/O and other USB operations. The device handle
521 * is preallocated for you, you can retrieve the device in question
522 * through handle->dev.
524 * Your backend should allocate any internal resources required for I/O
525 * and other operations so that those operations can happen (hopefully)
526 * without hiccup. This is also a good place to inform libusbx that it
527 * should monitor certain file descriptors related to this device -
528 * see the usbi_add_pollfd() function.
530 * This function should not generate any bus I/O and should not block.
532 * This function is called when the user attempts to obtain a device
533 * handle for a device.
537 * - LIBUSB_ERROR_ACCESS if the user has insufficient permissions
538 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since
540 * - another LIBUSB_ERROR code on other failure
542 * Do not worry about freeing the handle on failed open, the upper layers
545 int (*open)(struct libusb_device_handle *handle);
547 /* Close a device such that the handle cannot be used again. Your backend
548 * should destroy any resources that were allocated in the open path.
549 * This may also be a good place to call usbi_remove_pollfd() to inform
550 * libusbx of any file descriptors associated with this device that should
551 * no longer be monitored.
553 * This function is called when the user closes a device handle.
555 void (*close)(struct libusb_device_handle *handle);
557 /* Retrieve the device descriptor from a device.
559 * The descriptor should be retrieved from memory, NOT via bus I/O to the
560 * device. This means that you may have to cache it in a private structure
561 * during get_device_list enumeration. Alternatively, you may be able
562 * to retrieve it from a kernel interface (some Linux setups can do this)
563 * still without generating bus I/O.
565 * This function is expected to write DEVICE_DESC_LENGTH (18) bytes into
566 * buffer, which is guaranteed to be big enough.
568 * This function is called when sanity-checking a device before adding
569 * it to the list of discovered devices, and also when the user requests
570 * to read the device descriptor.
572 * This function is expected to return the descriptor in bus-endian format
573 * (LE). If it returns the multi-byte values in host-endian format,
574 * set the host_endian output parameter to "1".
576 * Return 0 on success or a LIBUSB_ERROR code on failure.
578 int (*get_device_descriptor)(struct libusb_device *device,
579 unsigned char *buffer, int *host_endian);
581 /* Get the ACTIVE configuration descriptor for a device.
583 * The descriptor should be retrieved from memory, NOT via bus I/O to the
584 * device. This means that you may have to cache it in a private structure
585 * during get_device_list enumeration. You may also have to keep track
586 * of which configuration is active when the user changes it.
588 * This function is expected to write len bytes of data into buffer, which
589 * is guaranteed to be big enough. If you can only do a partial write,
590 * return an error code.
592 * This function is expected to return the descriptor in bus-endian format
593 * (LE). If it returns the multi-byte values in host-endian format,
594 * set the host_endian output parameter to "1".
598 * - LIBUSB_ERROR_NOT_FOUND if the device is in unconfigured state
599 * - another LIBUSB_ERROR code on other failure
601 int (*get_active_config_descriptor)(struct libusb_device *device,
602 unsigned char *buffer, size_t len, int *host_endian);
604 /* Get a specific configuration descriptor for a device.
606 * The descriptor should be retrieved from memory, NOT via bus I/O to the
607 * device. This means that you may have to cache it in a private structure
608 * during get_device_list enumeration.
610 * The requested descriptor is expressed as a zero-based index (i.e. 0
611 * indicates that we are requesting the first descriptor). The index does
612 * not (necessarily) equal the bConfigurationValue of the configuration
615 * This function is expected to write len bytes of data into buffer, which
616 * is guaranteed to be big enough. If you can only do a partial write,
617 * return an error code.
619 * This function is expected to return the descriptor in bus-endian format
620 * (LE). If it returns the multi-byte values in host-endian format,
621 * set the host_endian output parameter to "1".
623 * Return 0 on success or a LIBUSB_ERROR code on failure.
625 int (*get_config_descriptor)(struct libusb_device *device,
626 uint8_t config_index, unsigned char *buffer, size_t len,
629 /* Get the bConfigurationValue for the active configuration for a device.
630 * Optional. This should only be implemented if you can retrieve it from
631 * cache (don't generate I/O).
633 * If you cannot retrieve this from cache, either do not implement this
634 * function, or return LIBUSB_ERROR_NOT_SUPPORTED. This will cause
635 * libusbx to retrieve the information through a standard control transfer.
637 * This function must be non-blocking.
640 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
642 * - LIBUSB_ERROR_NOT_SUPPORTED if the value cannot be retrieved without
644 * - another LIBUSB_ERROR code on other failure.
646 int (*get_configuration)(struct libusb_device_handle *handle, int *config);
648 /* Set the active configuration for a device.
650 * A configuration value of -1 should put the device in unconfigured state.
652 * This function can block.
656 * - LIBUSB_ERROR_NOT_FOUND if the configuration does not exist
657 * - LIBUSB_ERROR_BUSY if interfaces are currently claimed (and hence
658 * configuration cannot be changed)
659 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
661 * - another LIBUSB_ERROR code on other failure.
663 int (*set_configuration)(struct libusb_device_handle *handle, int config);
665 /* Claim an interface. When claimed, the application can then perform
666 * I/O to an interface's endpoints.
668 * This function should not generate any bus I/O and should not block.
669 * Interface claiming is a logical operation that simply ensures that
670 * no other drivers/applications are using the interface, and after
671 * claiming, no other drivers/applicatiosn can use the interface because
676 * - LIBUSB_ERROR_NOT_FOUND if the interface does not exist
677 * - LIBUSB_ERROR_BUSY if the interface is in use by another driver/app
678 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
680 * - another LIBUSB_ERROR code on other failure
682 int (*claim_interface)(struct libusb_device_handle *handle, int interface_number);
684 /* Release a previously claimed interface.
686 * This function should also generate a SET_INTERFACE control request,
687 * resetting the alternate setting of that interface to 0. It's OK for
688 * this function to block as a result.
690 * You will only ever be asked to release an interface which was
691 * successfully claimed earlier.
695 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
697 * - another LIBUSB_ERROR code on other failure
699 int (*release_interface)(struct libusb_device_handle *handle, int interface_number);
701 /* Set the alternate setting for an interface.
703 * You will only ever be asked to set the alternate setting for an
704 * interface which was successfully claimed earlier.
706 * It's OK for this function to block.
710 * - LIBUSB_ERROR_NOT_FOUND if the alternate setting does not exist
711 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
713 * - another LIBUSB_ERROR code on other failure
715 int (*set_interface_altsetting)(struct libusb_device_handle *handle,
716 int interface_number, int altsetting);
718 /* Clear a halt/stall condition on an endpoint.
720 * It's OK for this function to block.
724 * - LIBUSB_ERROR_NOT_FOUND if the endpoint does not exist
725 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
727 * - another LIBUSB_ERROR code on other failure
729 int (*clear_halt)(struct libusb_device_handle *handle,
730 unsigned char endpoint);
732 /* Perform a USB port reset to reinitialize a device.
734 * If possible, the handle should still be usable after the reset
735 * completes, assuming that the device descriptors did not change during
736 * reset and all previous interface state can be restored.
738 * If something changes, or you cannot easily locate/verify the resetted
739 * device, return LIBUSB_ERROR_NOT_FOUND. This prompts the application
740 * to close the old handle and re-enumerate the device.
744 * - LIBUSB_ERROR_NOT_FOUND if re-enumeration is required, or if the device
745 * has been disconnected since it was opened
746 * - another LIBUSB_ERROR code on other failure
748 int (*reset_device)(struct libusb_device_handle *handle);
750 /* Determine if a kernel driver is active on an interface. Optional.
752 * The presence of a kernel driver on an interface indicates that any
753 * calls to claim_interface would fail with the LIBUSB_ERROR_BUSY code.
756 * - 0 if no driver is active
757 * - 1 if a driver is active
758 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
760 * - another LIBUSB_ERROR code on other failure
762 int (*kernel_driver_active)(struct libusb_device_handle *handle,
763 int interface_number);
765 /* Detach a kernel driver from an interface. Optional.
767 * After detaching a kernel driver, the interface should be available
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 * - another LIBUSB_ERROR code on other failure
778 int (*detach_kernel_driver)(struct libusb_device_handle *handle,
779 int interface_number);
781 /* Attach a kernel driver to an interface. Optional.
783 * Reattach a kernel driver to the device.
787 * - LIBUSB_ERROR_NOT_FOUND if no kernel driver was active
788 * - LIBUSB_ERROR_INVALID_PARAM if the interface does not exist
789 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
791 * - LIBUSB_ERROR_BUSY if a program or driver has claimed the interface,
792 * preventing reattachment
793 * - another LIBUSB_ERROR code on other failure
795 int (*attach_kernel_driver)(struct libusb_device_handle *handle,
796 int interface_number);
798 /* Destroy a device. Optional.
800 * This function is called when the last reference to a device is
801 * destroyed. It should free any resources allocated in the get_device_list
804 void (*destroy_device)(struct libusb_device *dev);
806 /* Submit a transfer. Your implementation should take the transfer,
807 * morph it into whatever form your platform requires, and submit it
810 * This function must not block.
814 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
815 * - another LIBUSB_ERROR code on other failure
817 int (*submit_transfer)(struct usbi_transfer *itransfer);
819 /* Cancel a previously submitted transfer.
821 * This function must not block. The transfer cancellation must complete
822 * later, resulting in a call to usbi_handle_transfer_cancellation()
823 * from the context of handle_events.
825 int (*cancel_transfer)(struct usbi_transfer *itransfer);
827 /* Clear a transfer as if it has completed or cancelled, but do not
828 * report any completion/cancellation to the library. You should free
829 * all private data from the transfer as if you were just about to report
830 * completion or cancellation.
832 * This function might seem a bit out of place. It is used when libusbx
833 * detects a disconnected device - it calls this function for all pending
834 * transfers before reporting completion (with the disconnect code) to
835 * the user. Maybe we can improve upon this internal interface in future.
837 void (*clear_transfer_priv)(struct usbi_transfer *itransfer);
839 /* Handle any pending events. This involves monitoring any active
840 * transfers and processing their completion or cancellation.
842 * The function is passed an array of pollfd structures (size nfds)
843 * as a result of the poll() system call. The num_ready parameter
844 * indicates the number of file descriptors that have reported events
845 * (i.e. the poll() return value). This should be enough information
846 * for you to determine which actions need to be taken on the currently
849 * For any cancelled transfers, call usbi_handle_transfer_cancellation().
850 * For completed transfers, call usbi_handle_transfer_completion().
851 * For control/bulk/interrupt transfers, populate the "transferred"
852 * element of the appropriate usbi_transfer structure before calling the
853 * above functions. For isochronous transfers, populate the status and
854 * transferred fields of the iso packet descriptors of the transfer.
856 * This function should also be able to detect disconnection of the
857 * device, reporting that situation with usbi_handle_disconnect().
859 * When processing an event related to a transfer, you probably want to
860 * take usbi_transfer.lock to prevent races. See the documentation for
861 * the usbi_transfer structure.
863 * Return 0 on success, or a LIBUSB_ERROR code on failure.
865 int (*handle_events)(struct libusb_context *ctx,
866 struct pollfd *fds, POLL_NFDS_TYPE nfds, int num_ready);
868 /* Get time from specified clock. At least two clocks must be implemented
869 by the backend: USBI_CLOCK_REALTIME, and USBI_CLOCK_MONOTONIC.
871 Description of clocks:
872 USBI_CLOCK_REALTIME : clock returns time since system epoch.
873 USBI_CLOCK_MONOTONIC: clock returns time since unspecified start
876 int (*clock_gettime)(int clkid, struct timespec *tp);
878 #ifdef USBI_TIMERFD_AVAILABLE
879 /* clock ID of the clock that should be used for timerfd */
880 clockid_t (*get_timerfd_clockid)(void);
883 /* Number of bytes to reserve for per-device private backend data.
884 * This private data area is accessible through the "os_priv" field of
885 * struct libusb_device. */
886 size_t device_priv_size;
888 /* Number of bytes to reserve for per-handle private backend data.
889 * This private data area is accessible through the "os_priv" field of
890 * struct libusb_device. */
891 size_t device_handle_priv_size;
893 /* Number of bytes to reserve for per-transfer private backend data.
894 * This private data area is accessible by calling
895 * usbi_transfer_get_os_priv() on the appropriate usbi_transfer instance.
897 size_t transfer_priv_size;
899 /* Mumber of additional bytes for os_priv for each iso packet.
900 * Can your backend use this? */
901 /* FIXME: linux can't use this any more. if other OS's cannot either,
902 * then remove this */
903 size_t add_iso_packet_size;
906 extern const struct usbi_os_backend * const usbi_backend;
908 extern const struct usbi_os_backend linux_usbfs_backend;
909 extern const struct usbi_os_backend darwin_backend;
910 extern const struct usbi_os_backend openbsd_backend;
911 extern const struct usbi_os_backend windows_backend;