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 #define DEVICE_DESC_LENGTH 18
34 #define USB_MAXENDPOINTS 32
35 #define USB_MAXINTERFACES 32
36 #define USB_MAXCONFIG 8
39 struct list_head *prev, *next;
42 /* Get an entry from the list
43 * ptr - the address of this list_head element in "type"
44 * type - the data type that contains "member"
45 * member - the list_head element in "type"
47 #define list_entry(ptr, type, member) \
48 ((type *)((char *)(ptr) - (unsigned long)(&((type *)0L)->member)))
50 /* Get each entry from a list
51 * pos - A structure pointer has a "member" element
53 * member - the list_head element in "pos"
55 #define list_for_each_entry(pos, head, member) \
56 for (pos = list_entry((head)->next, typeof(*pos), member); \
57 &pos->member != (head); \
58 pos = list_entry(pos->member.next, typeof(*pos), member))
60 #define list_for_each_entry_safe(pos, n, head, member) \
61 for (pos = list_entry((head)->next, typeof(*pos), member), \
62 n = list_entry(pos->member.next, typeof(*pos), member); \
63 &pos->member != (head); \
64 pos = n, n = list_entry(n->member.next, typeof(*n), member))
66 #define list_empty(entry) ((entry)->next == (entry))
68 static inline void list_init(struct list_head *entry)
70 entry->prev = entry->next = entry;
73 static inline void list_add(struct list_head *entry, struct list_head *head)
75 entry->next = head->next;
78 head->next->prev = entry;
82 static inline void list_add_tail(struct list_head *entry,
83 struct list_head *head)
86 entry->prev = head->prev;
88 head->prev->next = entry;
92 static inline void list_del(struct list_head *entry)
94 entry->next->prev = entry->prev;
95 entry->prev->next = entry->next;
98 #define container_of(ptr, type, member) ({ \
99 const typeof( ((type *)0)->member ) *__mptr = (ptr); \
100 (type *)( (char *)__mptr - offsetof(type,member) );})
102 #define MIN(a, b) ((a) < (b) ? (a) : (b))
103 #define MAX(a, b) ((a) > (b) ? (a) : (b))
105 #define TIMESPEC_IS_SET(ts) ((ts)->tv_sec != 0 || (ts)->tv_nsec != 0)
107 enum usbi_log_level {
114 void usbi_log(struct libusb_context *ctx, enum usbi_log_level,
115 const char *function, const char *format, ...);
117 #ifdef ENABLE_LOGGING
118 #define _usbi_log(ctx, level, fmt...) usbi_log(ctx, level, __FUNCTION__, fmt)
120 #define _usbi_log(ctx, level, fmt...)
123 #ifdef ENABLE_DEBUG_LOGGING
124 #define usbi_dbg(fmt...) _usbi_log(NULL, LOG_LEVEL_DEBUG, fmt)
126 #define usbi_dbg(fmt...)
129 #define usbi_info(ctx, fmt...) _usbi_log(ctx, LOG_LEVEL_INFO, fmt)
130 #define usbi_warn(ctx, fmt...) _usbi_log(ctx, LOG_LEVEL_WARNING, fmt)
131 #define usbi_err(ctx, fmt...) _usbi_log(ctx, LOG_LEVEL_ERROR, fmt)
133 #define USBI_GET_CONTEXT(ctx) if (!(ctx)) (ctx) = usbi_default_context
134 #define DEVICE_CTX(dev) ((dev)->ctx)
135 #define HANDLE_CTX(handle) (DEVICE_CTX((handle)->dev))
136 #define TRANSFER_CTX(transfer) (HANDLE_CTX((transfer)->dev_handle))
137 #define ITRANSFER_CTX(transfer) \
138 (TRANSFER_CTX(__USBI_TRANSFER_TO_LIBUSB_TRANSFER(transfer)))
140 /* Internal abstraction for thread synchronization */
141 #if defined(OS_LINUX) || defined(OS_DARWIN)
142 #include <os/threads_posix.h>
145 extern struct libusb_context *usbi_default_context;
147 struct libusb_context {
151 /* internal control pipe, used for interrupting event handling when
152 * something needs to modify poll fds. */
155 struct list_head usb_devs;
156 usbi_mutex_t usb_devs_lock;
158 /* A list of open handles. Backends are free to traverse this if required.
160 struct list_head open_devs;
161 usbi_mutex_t open_devs_lock;
163 /* this is a list of in-flight transfer handles, sorted by timeout
164 * expiration. URBs to timeout the soonest are placed at the beginning of
165 * the list, URBs that will time out later are placed after, and urbs with
166 * infinite timeout are always placed at the very end. */
167 struct list_head flying_transfers;
168 usbi_mutex_t flying_transfers_lock;
170 /* list of poll fds */
171 struct list_head pollfds;
172 usbi_mutex_t pollfds_lock;
174 /* a counter that is set when we want to interrupt event handling, in order
175 * to modify the poll fd set. and a lock to protect it. */
176 unsigned int pollfd_modify;
177 usbi_mutex_t pollfd_modify_lock;
179 /* user callbacks for pollfd changes */
180 libusb_pollfd_added_cb fd_added_cb;
181 libusb_pollfd_removed_cb fd_removed_cb;
182 void *fd_cb_user_data;
184 /* ensures that only one thread is handling events at any one time */
185 usbi_mutex_t events_lock;
187 /* used to see if there is an active thread doing event handling */
188 int event_handler_active;
190 /* used to wait for event completion in threads other than the one that is
192 usbi_mutex_t event_waiters_lock;
193 usbi_cond_t event_waiters_cond;
195 #ifdef USBI_TIMERFD_AVAILABLE
196 /* used for timeout handling, if supported by OS.
197 * this timerfd is maintained to trigger on the next pending timeout */
202 #ifdef USBI_TIMERFD_AVAILABLE
203 #define usbi_using_timerfd(ctx) ((ctx)->timerfd >= 0)
205 #define usbi_using_timerfd(ctx) (0)
208 struct libusb_device {
209 /* lock protects refcnt, everything else is finalized at initialization
214 struct libusb_context *ctx;
217 uint8_t device_address;
218 uint8_t num_configurations;
220 struct list_head list;
221 unsigned long session_data;
222 unsigned char os_priv[0];
225 struct libusb_device_handle {
226 /* lock protects claimed_interfaces */
228 unsigned long claimed_interfaces;
230 struct list_head list;
231 struct libusb_device *dev;
232 unsigned char os_priv[0];
235 #define USBI_TRANSFER_TIMED_OUT (1<<0)
238 USBI_CLOCK_MONOTONIC,
242 /* in-memory transfer layout:
244 * 1. struct usbi_transfer
245 * 2. struct libusb_transfer (which includes iso packets) [variable size]
246 * 3. os private data [variable size]
248 * from a libusb_transfer, you can get the usbi_transfer by rewinding the
249 * appropriate number of bytes.
250 * the usbi_transfer includes the number of allocated packets, so you can
251 * determine the size of the transfer and hence the start and length of the
255 struct usbi_transfer {
257 struct list_head list;
258 struct timeval timeout;
262 /* this lock is held during libusb_submit_transfer() and
263 * libusb_cancel_transfer() (allowing the OS backend to prevent duplicate
264 * cancellation, submission-during-cancellation, etc). the OS backend
265 * should also take this lock in the handle_events path, to prevent the user
266 * cancelling the transfer from another thread while you are processing
267 * its completion (presumably there would be races within your OS backend
268 * if this were possible). */
272 #define __USBI_TRANSFER_TO_LIBUSB_TRANSFER(transfer) \
273 ((struct libusb_transfer *)(((unsigned char *)(transfer)) \
274 + sizeof(struct usbi_transfer)))
275 #define __LIBUSB_TRANSFER_TO_USBI_TRANSFER(transfer) \
276 ((struct usbi_transfer *)(((unsigned char *)(transfer)) \
277 - sizeof(struct usbi_transfer)))
279 static inline void *usbi_transfer_get_os_priv(struct usbi_transfer *transfer)
281 return ((unsigned char *)transfer) + sizeof(struct usbi_transfer)
282 + sizeof(struct libusb_transfer)
283 + (transfer->num_iso_packets
284 * sizeof(struct libusb_iso_packet_descriptor));
289 /* All standard descriptors have these 2 fields in common */
290 struct usb_descriptor_header {
292 uint8_t bDescriptorType;
295 /* shared data and functions */
297 int usbi_io_init(struct libusb_context *ctx);
298 void usbi_io_exit(struct libusb_context *ctx);
300 struct libusb_device *usbi_alloc_device(struct libusb_context *ctx,
301 unsigned long session_id);
302 struct libusb_device *usbi_get_device_by_session_id(struct libusb_context *ctx,
303 unsigned long session_id);
304 int usbi_sanitize_device(struct libusb_device *dev);
305 void usbi_handle_disconnect(struct libusb_device_handle *handle);
307 int usbi_handle_transfer_completion(struct usbi_transfer *itransfer,
308 enum libusb_transfer_status status);
309 int usbi_handle_transfer_cancellation(struct usbi_transfer *transfer);
311 int usbi_parse_descriptor(unsigned char *source, char *descriptor, void *dest,
313 int usbi_get_config_index_by_value(struct libusb_device *dev,
314 uint8_t bConfigurationValue, int *idx);
319 /* must come first */
320 struct libusb_pollfd pollfd;
322 struct list_head list;
325 int usbi_add_pollfd(struct libusb_context *ctx, int fd, short events);
326 void usbi_remove_pollfd(struct libusb_context *ctx, int fd);
328 /* device discovery */
330 /* we traverse usbfs without knowing how many devices we are going to find.
331 * so we create this discovered_devs model which is similar to a linked-list
332 * which grows when required. it can be freed once discovery has completed,
333 * eliminating the need for a list node in the libusb_device structure
335 struct discovered_devs {
338 struct libusb_device *devices[0];
341 struct discovered_devs *discovered_devs_append(
342 struct discovered_devs *discdevs, struct libusb_device *dev);
346 /* This is the interface that OS backends need to implement.
347 * All fields are mandatory, except ones explicitly noted as optional. */
348 struct usbi_os_backend {
349 /* A human-readable name for your backend, e.g. "Linux usbfs" */
352 /* Perform initialization of your backend. You might use this function
353 * to determine specific capabilities of the system, allocate required
354 * data structures for later, etc.
356 * This function is called when a libusb user initializes the library
359 * Return 0 on success, or a LIBUSB_ERROR code on failure.
361 int (*init)(struct libusb_context *ctx);
363 /* Deinitialization. Optional. This function should destroy anything
364 * that was set up by init.
366 * This function is called when the user deinitializes the library.
370 /* Enumerate all the USB devices on the system, returning them in a list
371 * of discovered devices.
373 * Your implementation should enumerate all devices on the system,
374 * regardless of whether they have been seen before or not.
376 * When you have found a device, compute a session ID for it. The session
377 * ID should uniquely represent that particular device for that particular
378 * connection session since boot (i.e. if you disconnect and reconnect a
379 * device immediately after, it should be assigned a different session ID).
380 * If your OS cannot provide a unique session ID as described above,
381 * presenting a session ID of (bus_number << 8 | device_address) should
382 * be sufficient. Bus numbers and device addresses wrap and get reused,
383 * but that is an unlikely case.
385 * After computing a session ID for a device, call
386 * usbi_get_device_by_session_id(). This function checks if libusb already
387 * knows about the device, and if so, it provides you with a libusb_device
390 * If usbi_get_device_by_session_id() returns NULL, it is time to allocate
391 * a new device structure for the device. Call usbi_alloc_device() to
392 * obtain a new libusb_device structure with reference count 1. Populate
393 * the bus_number and device_address attributes of the new device, and
394 * perform any other internal backend initialization you need to do. At
395 * this point, you should be ready to provide device descriptors and so
396 * on through the get_*_descriptor functions. Finally, call
397 * usbi_sanitize_device() to perform some final sanity checks on the
398 * device. Assuming all of the above succeeded, we can now continue.
399 * If any of the above failed, remember to unreference the device that
400 * was returned by usbi_alloc_device().
402 * At this stage we have a populated libusb_device structure (either one
403 * that was found earlier, or one that we have just allocated and
404 * populated). This can now be added to the discovered devices list
405 * using discovered_devs_append(). Note that discovered_devs_append()
406 * may reallocate the list, returning a new location for it, and also
407 * note that reallocation can fail. Your backend should handle these
408 * error conditions appropriately.
410 * This function should not generate any bus I/O and should not block.
411 * If I/O is required (e.g. reading the active configuration value), it is
412 * OK to ignore these suggestions :)
414 * This function is executed when the user wishes to retrieve a list
415 * of USB devices connected to the system.
417 * Return 0 on success, or a LIBUSB_ERROR code on failure.
419 int (*get_device_list)(struct libusb_context *ctx,
420 struct discovered_devs **discdevs);
422 /* Open a device for I/O and other USB operations. The device handle
423 * is preallocated for you, you can retrieve the device in question
424 * through handle->dev.
426 * Your backend should allocate any internal resources required for I/O
427 * and other operations so that those operations can happen (hopefully)
428 * without hiccup. This is also a good place to inform libusb that it
429 * should monitor certain file descriptors related to this device -
430 * see the usbi_add_pollfd() function.
432 * This function should not generate any bus I/O and should not block.
434 * This function is called when the user attempts to obtain a device
435 * handle for a device.
439 * - LIBUSB_ERROR_ACCESS if the user has insufficient permissions
440 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since
442 * - another LIBUSB_ERROR code on other failure
444 * Do not worry about freeing the handle on failed open, the upper layers
447 int (*open)(struct libusb_device_handle *handle);
449 /* Close a device such that the handle cannot be used again. Your backend
450 * should destroy any resources that were allocated in the open path.
451 * This may also be a good place to call usbi_remove_pollfd() to inform
452 * libusb of any file descriptors associated with this device that should
453 * no longer be monitored.
455 * This function is called when the user closes a device handle.
457 void (*close)(struct libusb_device_handle *handle);
459 /* Retrieve the device descriptor from a device.
461 * The descriptor should be retrieved from memory, NOT via bus I/O to the
462 * device. This means that you may have to cache it in a private structure
463 * during get_device_list enumeration. Alternatively, you may be able
464 * to retrieve it from a kernel interface (some Linux setups can do this)
465 * still without generating bus I/O.
467 * This function is expected to write DEVICE_DESC_LENGTH (18) bytes into
468 * buffer, which is guaranteed to be big enough.
470 * This function is called when sanity-checking a device before adding
471 * it to the list of discovered devices, and also when the user requests
472 * to read the device descriptor.
474 * This function is expected to return the descriptor in bus-endian format
475 * (LE). If it returns the multi-byte values in host-endian format,
476 * set the host_endian output parameter to "1".
478 * Return 0 on success or a LIBUSB_ERROR code on failure.
480 int (*get_device_descriptor)(struct libusb_device *device,
481 unsigned char *buffer, int *host_endian);
483 /* Get the ACTIVE configuration descriptor for a device.
485 * The descriptor should be retrieved from memory, NOT via bus I/O to the
486 * device. This means that you may have to cache it in a private structure
487 * during get_device_list enumeration. You may also have to keep track
488 * of which configuration is active when the user changes it.
490 * This function is expected to write len bytes of data into buffer, which
491 * is guaranteed to be big enough. If you can only do a partial write,
492 * return an error code.
494 * This function is expected to return the descriptor in bus-endian format
495 * (LE). If it returns the multi-byte values in host-endian format,
496 * set the host_endian output parameter to "1".
500 * - LIBUSB_ERROR_NOT_FOUND if the device is in unconfigured state
501 * - another LIBUSB_ERROR code on other failure
503 int (*get_active_config_descriptor)(struct libusb_device *device,
504 unsigned char *buffer, size_t len, int *host_endian);
506 /* Get a specific configuration descriptor for a device.
508 * The descriptor should be retrieved from memory, NOT via bus I/O to the
509 * device. This means that you may have to cache it in a private structure
510 * during get_device_list enumeration.
512 * The requested descriptor is expressed as a zero-based index (i.e. 0
513 * indicates that we are requesting the first descriptor). The index does
514 * not (necessarily) equal the bConfigurationValue of the configuration
517 * This function is expected to write len bytes of data into buffer, which
518 * is guaranteed to be big enough. If you can only do a partial write,
519 * return an error code.
521 * This function is expected to return the descriptor in bus-endian format
522 * (LE). If it returns the multi-byte values in host-endian format,
523 * set the host_endian output parameter to "1".
525 * Return 0 on success or a LIBUSB_ERROR code on failure.
527 int (*get_config_descriptor)(struct libusb_device *device,
528 uint8_t config_index, unsigned char *buffer, size_t len,
531 /* Get the bConfigurationValue for the active configuration for a device.
532 * Optional. This should only be implemented if you can retrieve it from
533 * cache (don't generate I/O).
535 * If you cannot retrieve this from cache, either do not implement this
536 * function, or return LIBUSB_ERROR_NOT_SUPPORTED. This will cause
537 * libusb to retrieve the information through a standard control transfer.
539 * This function must be non-blocking.
542 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
544 * - LIBUSB_ERROR_NOT_SUPPORTED if the value cannot be retrieved without
546 * - another LIBUSB_ERROR code on other failure.
548 int (*get_configuration)(struct libusb_device_handle *handle, int *config);
550 /* Set the active configuration for a device.
552 * A configuration value of -1 should put the device in unconfigured state.
554 * This function can block.
558 * - LIBUSB_ERROR_NOT_FOUND if the configuration does not exist
559 * - LIBUSB_ERROR_BUSY if interfaces are currently claimed (and hence
560 * configuration cannot be changed)
561 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
563 * - another LIBUSB_ERROR code on other failure.
565 int (*set_configuration)(struct libusb_device_handle *handle, int config);
567 /* Claim an interface. When claimed, the application can then perform
568 * I/O to an interface's endpoints.
570 * This function should not generate any bus I/O and should not block.
571 * Interface claiming is a logical operation that simply ensures that
572 * no other drivers/applications are using the interface, and after
573 * claiming, no other drivers/applicatiosn can use the interface because
578 * - LIBUSB_ERROR_NOT_FOUND if the interface does not exist
579 * - LIBUSB_ERROR_BUSY if the interface is in use by another driver/app
580 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
582 * - another LIBUSB_ERROR code on other failure
584 int (*claim_interface)(struct libusb_device_handle *handle, int interface_number);
586 /* Release a previously claimed interface.
588 * This function should also generate a SET_INTERFACE control request,
589 * resetting the alternate setting of that interface to 0. It's OK for
590 * this function to block as a result.
592 * You will only ever be asked to release an interface which was
593 * successfully claimed earlier.
597 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
599 * - another LIBUSB_ERROR code on other failure
601 int (*release_interface)(struct libusb_device_handle *handle, int interface_number);
603 /* Set the alternate setting for an interface.
605 * You will only ever be asked to set the alternate setting for an
606 * interface which was successfully claimed earlier.
608 * It's OK for this function to block.
612 * - LIBUSB_ERROR_NOT_FOUND if the alternate setting does not exist
613 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
615 * - another LIBUSB_ERROR code on other failure
617 int (*set_interface_altsetting)(struct libusb_device_handle *handle,
618 int interface_number, int altsetting);
620 /* Clear a halt/stall condition on an endpoint.
622 * It's OK for this function to block.
626 * - LIBUSB_ERROR_NOT_FOUND if the endpoint does not exist
627 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
629 * - another LIBUSB_ERROR code on other failure
631 int (*clear_halt)(struct libusb_device_handle *handle,
632 unsigned char endpoint);
634 /* Perform a USB port reset to reinitialize a device.
636 * If possible, the handle should still be usable after the reset
637 * completes, assuming that the device descriptors did not change during
638 * reset and all previous interface state can be restored.
640 * If something changes, or you cannot easily locate/verify the resetted
641 * device, return LIBUSB_ERROR_NOT_FOUND. This prompts the application
642 * to close the old handle and re-enumerate the device.
646 * - LIBUSB_ERROR_NOT_FOUND if re-enumeration is required, or if the device
647 * has been disconnected since it was opened
648 * - another LIBUSB_ERROR code on other failure
650 int (*reset_device)(struct libusb_device_handle *handle);
652 /* Determine if a kernel driver is active on an interface. Optional.
654 * The presence of a kernel driver on an interface indicates that any
655 * calls to claim_interface would fail with the LIBUSB_ERROR_BUSY code.
658 * - 0 if no driver is active
659 * - 1 if a driver is active
660 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
662 * - another LIBUSB_ERROR code on other failure
664 int (*kernel_driver_active)(struct libusb_device_handle *handle,
665 int interface_number);
667 /* Detach a kernel driver from an interface. Optional.
669 * After detaching a kernel driver, the interface should be available
674 * - LIBUSB_ERROR_NOT_FOUND if no kernel driver was active
675 * - LIBUSB_ERROR_INVALID_PARAM if the interface 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 (*detach_kernel_driver)(struct libusb_device_handle *handle,
681 int interface_number);
683 /* Attach a kernel driver to an interface. Optional.
685 * Reattach a kernel driver to the device.
689 * - LIBUSB_ERROR_NOT_FOUND if no kernel driver was active
690 * - LIBUSB_ERROR_INVALID_PARAM if the interface does not exist
691 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
693 * - LIBUSB_ERROR_BUSY if a program or driver has claimed the interface,
694 * preventing reattachment
695 * - another LIBUSB_ERROR code on other failure
697 int (*attach_kernel_driver)(struct libusb_device_handle *handle,
698 int interface_number);
700 /* Destroy a device. Optional.
702 * This function is called when the last reference to a device is
703 * destroyed. It should free any resources allocated in the get_device_list
706 void (*destroy_device)(struct libusb_device *dev);
708 /* Submit a transfer. Your implementation should take the transfer,
709 * morph it into whatever form your platform requires, and submit it
712 * This function must not block.
716 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
717 * - another LIBUSB_ERROR code on other failure
719 int (*submit_transfer)(struct usbi_transfer *itransfer);
721 /* Cancel a previously submitted transfer.
723 * This function must not block. The transfer cancellation must complete
724 * later, resulting in a call to usbi_handle_transfer_cancellation()
725 * from the context of handle_events.
727 int (*cancel_transfer)(struct usbi_transfer *itransfer);
729 /* Clear a transfer as if it has completed or cancelled, but do not
730 * report any completion/cancellation to the library. You should free
731 * all private data from the transfer as if you were just about to report
732 * completion or cancellation.
734 * This function might seem a bit out of place. It is used when libusb
735 * detects a disconnected device - it calls this function for all pending
736 * transfers before reporting completion (with the disconnect code) to
737 * the user. Maybe we can improve upon this internal interface in future.
739 void (*clear_transfer_priv)(struct usbi_transfer *itransfer);
741 /* Handle any pending events. This involves monitoring any active
742 * transfers and processing their completion or cancellation.
744 * The function is passed an array of pollfd structures (size nfds)
745 * as a result of the poll() system call. The num_ready parameter
746 * indicates the number of file descriptors that have reported events
747 * (i.e. the poll() return value). This should be enough information
748 * for you to determine which actions need to be taken on the currently
751 * For any cancelled transfers, call usbi_handle_transfer_cancellation().
752 * For completed transfers, call usbi_handle_transfer_completion().
753 * For control/bulk/interrupt transfers, populate the "transferred"
754 * element of the appropriate usbi_transfer structure before calling the
755 * above functions. For isochronous transfers, populate the status and
756 * transferred fields of the iso packet descriptors of the transfer.
758 * This function should also be able to detect disconnection of the
759 * device, reporting that situation with usbi_handle_disconnect().
761 * When processing an event related to a transfer, you probably want to
762 * take usbi_transfer.lock to prevent races. See the documentation for
763 * the usbi_transfer structure.
765 * Return 0 on success, or a LIBUSB_ERROR code on failure.
767 int (*handle_events)(struct libusb_context *ctx,
768 struct pollfd *fds, nfds_t nfds, int num_ready);
770 /* Get time from specified clock. At least two clocks must be implemented
771 by the backend: USBI_CLOCK_REALTIME, and USBI_CLOCK_MONOTONIC.
773 Description of clocks:
774 USBI_CLOCK_REALTIME : clock returns time since system epoch.
775 USBI_CLOCK_MONOTONIC: clock returns time since unspecified start
778 int (*clock_gettime)(int clkid, struct timespec *tp);
780 #ifdef USBI_TIMERFD_AVAILABLE
781 /* clock ID of the clock that should be used for timerfd */
782 clockid_t (*get_timerfd_clockid)(void);
785 /* Number of bytes to reserve for per-device private backend data.
786 * This private data area is accessible through the "os_priv" field of
787 * struct libusb_device. */
788 size_t device_priv_size;
790 /* Number of bytes to reserve for per-handle private backend data.
791 * This private data area is accessible through the "os_priv" field of
792 * struct libusb_device. */
793 size_t device_handle_priv_size;
795 /* Number of bytes to reserve for per-transfer private backend data.
796 * This private data area is accessible by calling
797 * usbi_transfer_get_os_priv() on the appropriate usbi_transfer instance.
799 size_t transfer_priv_size;
801 /* Mumber of additional bytes for os_priv for each iso packet.
802 * Can your backend use this? */
803 /* FIXME: linux can't use this any more. if other OS's cannot either,
804 * then remove this */
805 size_t add_iso_packet_size;
808 extern const struct usbi_os_backend * const usbi_backend;
810 extern const struct usbi_os_backend linux_usbfs_backend;
811 extern const struct usbi_os_backend darwin_backend;