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"
54 * type - the type of the first parameter
56 #define list_for_each_entry(pos, head, member, type) \
57 for (pos = list_entry((head)->next, type, member); \
58 &pos->member != (head); \
59 pos = list_entry(pos->member.next, type, member))
61 #define list_for_each_entry_safe(pos, n, head, member, type) \
62 for (pos = list_entry((head)->next, type, member), \
63 n = list_entry(pos->member.next, type, member); \
64 &pos->member != (head); \
65 pos = n, n = list_entry(n->member.next, type, member))
67 #define list_empty(entry) ((entry)->next == (entry))
69 static inline void list_init(struct list_head *entry)
71 entry->prev = entry->next = entry;
74 static inline void list_add(struct list_head *entry, struct list_head *head)
76 entry->next = head->next;
79 head->next->prev = entry;
83 static inline void list_add_tail(struct list_head *entry,
84 struct list_head *head)
87 entry->prev = head->prev;
89 head->prev->next = entry;
93 static inline void list_del(struct list_head *entry)
95 entry->next->prev = entry->prev;
96 entry->prev->next = entry->next;
99 #define container_of(ptr, type, member) ({ \
100 const typeof( ((type *)0)->member ) *__mptr = (ptr); \
101 (type *)( (char *)__mptr - offsetof(type,member) );})
103 #define MIN(a, b) ((a) < (b) ? (a) : (b))
104 #define MAX(a, b) ((a) > (b) ? (a) : (b))
106 #define TIMESPEC_IS_SET(ts) ((ts)->tv_sec != 0 || (ts)->tv_nsec != 0)
108 enum usbi_log_level {
115 void usbi_log(struct libusb_context *ctx, enum usbi_log_level level,
116 const char *function, const char *format, ...);
118 #if !defined(_MSC_VER) || _MSC_VER > 1200
120 #ifdef ENABLE_LOGGING
121 #define _usbi_log(ctx, level, ...) usbi_log(ctx, level, __FUNCTION__, __VA_ARGS__)
123 #define _usbi_log(ctx, level, ...)
126 #ifdef ENABLE_DEBUG_LOGGING
127 #define usbi_dbg(...) _usbi_log(NULL, LOG_LEVEL_DEBUG, __VA_ARGS__)
129 #define usbi_dbg(...)
132 #define usbi_info(ctx, ...) _usbi_log(ctx, LOG_LEVEL_INFO, __VA_ARGS__)
133 #define usbi_warn(ctx, ...) _usbi_log(ctx, LOG_LEVEL_WARNING, __VA_ARGS__)
134 #define usbi_err(ctx, ...) _usbi_log(ctx, LOG_LEVEL_ERROR, __VA_ARGS__)
136 #else /* !defined(_MSC_VER) || _MSC_VER > 1200 */
138 void usbi_log_v(struct libusb_context *ctx, enum usbi_log_level level,
139 const char *function, const char *format, va_list args);
141 #ifdef ENABLE_LOGGING
142 #define LOG_BODY(ctxt, level) \
145 va_start (args, format); \
146 usbi_log_v(ctxt, level, "", format, args); \
150 #define LOG_BODY(ctxt, level) { }
153 static inline void usbi_info(struct libusb_context *ctx, const char *format,
155 LOG_BODY(ctx,LOG_LEVEL_INFO)
156 static inline void usbi_warn(struct libusb_context *ctx, const char *format,
158 LOG_BODY(ctx,LOG_LEVEL_WARNING)
159 static inline void usbi_err( struct libusb_context *ctx, const char *format,
161 LOG_BODY(ctx,LOG_LEVEL_ERROR)
163 static inline void usbi_dbg(const char *format, ...)
164 #ifdef ENABLE_DEBUG_LOGGING
165 LOG_BODY(NULL,LOG_LEVEL_DEBUG)
170 #endif /* !defined(_MSC_VER) || _MSC_VER > 1200 */
172 #define USBI_GET_CONTEXT(ctx) if (!(ctx)) (ctx) = usbi_default_context
173 #define DEVICE_CTX(dev) ((dev)->ctx)
174 #define HANDLE_CTX(handle) (DEVICE_CTX((handle)->dev))
175 #define TRANSFER_CTX(transfer) (HANDLE_CTX((transfer)->dev_handle))
176 #define ITRANSFER_CTX(transfer) \
177 (TRANSFER_CTX(__USBI_TRANSFER_TO_LIBUSB_TRANSFER(transfer)))
179 /* Internal abstraction for thread synchronization */
180 #if defined(OS_LINUX) || defined(OS_DARWIN)
181 #include <os/threads_posix.h>
184 extern struct libusb_context *usbi_default_context;
186 struct libusb_context {
190 /* internal control pipe, used for interrupting event handling when
191 * something needs to modify poll fds. */
194 struct list_head usb_devs;
195 usbi_mutex_t usb_devs_lock;
197 /* A list of open handles. Backends are free to traverse this if required.
199 struct list_head open_devs;
200 usbi_mutex_t open_devs_lock;
202 /* this is a list of in-flight transfer handles, sorted by timeout
203 * expiration. URBs to timeout the soonest are placed at the beginning of
204 * the list, URBs that will time out later are placed after, and urbs with
205 * infinite timeout are always placed at the very end. */
206 struct list_head flying_transfers;
207 usbi_mutex_t flying_transfers_lock;
209 /* list of poll fds */
210 struct list_head pollfds;
211 usbi_mutex_t pollfds_lock;
213 /* a counter that is set when we want to interrupt event handling, in order
214 * to modify the poll fd set. and a lock to protect it. */
215 unsigned int pollfd_modify;
216 usbi_mutex_t pollfd_modify_lock;
218 /* user callbacks for pollfd changes */
219 libusb_pollfd_added_cb fd_added_cb;
220 libusb_pollfd_removed_cb fd_removed_cb;
221 void *fd_cb_user_data;
223 /* ensures that only one thread is handling events at any one time */
224 usbi_mutex_t events_lock;
226 /* used to see if there is an active thread doing event handling */
227 int event_handler_active;
229 /* used to wait for event completion in threads other than the one that is
231 usbi_mutex_t event_waiters_lock;
232 usbi_cond_t event_waiters_cond;
234 #ifdef USBI_TIMERFD_AVAILABLE
235 /* used for timeout handling, if supported by OS.
236 * this timerfd is maintained to trigger on the next pending timeout */
241 #ifdef USBI_TIMERFD_AVAILABLE
242 #define usbi_using_timerfd(ctx) ((ctx)->timerfd >= 0)
244 #define usbi_using_timerfd(ctx) (0)
247 struct libusb_device {
248 /* lock protects refcnt, everything else is finalized at initialization
253 struct libusb_context *ctx;
256 uint8_t device_address;
257 uint8_t num_configurations;
259 struct list_head list;
260 unsigned long session_data;
261 unsigned char os_priv[0];
264 struct libusb_device_handle {
265 /* lock protects claimed_interfaces */
267 unsigned long claimed_interfaces;
269 struct list_head list;
270 struct libusb_device *dev;
271 unsigned char os_priv[0];
274 #define USBI_TRANSFER_TIMED_OUT (1<<0)
277 USBI_CLOCK_MONOTONIC,
281 /* in-memory transfer layout:
283 * 1. struct usbi_transfer
284 * 2. struct libusb_transfer (which includes iso packets) [variable size]
285 * 3. os private data [variable size]
287 * from a libusb_transfer, you can get the usbi_transfer by rewinding the
288 * appropriate number of bytes.
289 * the usbi_transfer includes the number of allocated packets, so you can
290 * determine the size of the transfer and hence the start and length of the
294 struct usbi_transfer {
296 struct list_head list;
297 struct timeval timeout;
301 /* this lock is held during libusb_submit_transfer() and
302 * libusb_cancel_transfer() (allowing the OS backend to prevent duplicate
303 * cancellation, submission-during-cancellation, etc). the OS backend
304 * should also take this lock in the handle_events path, to prevent the user
305 * cancelling the transfer from another thread while you are processing
306 * its completion (presumably there would be races within your OS backend
307 * if this were possible). */
311 #define __USBI_TRANSFER_TO_LIBUSB_TRANSFER(transfer) \
312 ((struct libusb_transfer *)(((unsigned char *)(transfer)) \
313 + sizeof(struct usbi_transfer)))
314 #define __LIBUSB_TRANSFER_TO_USBI_TRANSFER(transfer) \
315 ((struct usbi_transfer *)(((unsigned char *)(transfer)) \
316 - sizeof(struct usbi_transfer)))
318 static inline void *usbi_transfer_get_os_priv(struct usbi_transfer *transfer)
320 return ((unsigned char *)transfer) + sizeof(struct usbi_transfer)
321 + sizeof(struct libusb_transfer)
322 + (transfer->num_iso_packets
323 * sizeof(struct libusb_iso_packet_descriptor));
328 /* All standard descriptors have these 2 fields in common */
329 struct usb_descriptor_header {
331 uint8_t bDescriptorType;
334 /* shared data and functions */
336 int usbi_io_init(struct libusb_context *ctx);
337 void usbi_io_exit(struct libusb_context *ctx);
339 struct libusb_device *usbi_alloc_device(struct libusb_context *ctx,
340 unsigned long session_id);
341 struct libusb_device *usbi_get_device_by_session_id(struct libusb_context *ctx,
342 unsigned long session_id);
343 int usbi_sanitize_device(struct libusb_device *dev);
344 void usbi_handle_disconnect(struct libusb_device_handle *handle);
346 int usbi_handle_transfer_completion(struct usbi_transfer *itransfer,
347 enum libusb_transfer_status status);
348 int usbi_handle_transfer_cancellation(struct usbi_transfer *transfer);
350 int usbi_parse_descriptor(unsigned char *source, char *descriptor, void *dest,
352 int usbi_get_config_index_by_value(struct libusb_device *dev,
353 uint8_t bConfigurationValue, int *idx);
358 /* must come first */
359 struct libusb_pollfd pollfd;
361 struct list_head list;
364 int usbi_add_pollfd(struct libusb_context *ctx, int fd, short events);
365 void usbi_remove_pollfd(struct libusb_context *ctx, int fd);
367 /* device discovery */
369 /* we traverse usbfs without knowing how many devices we are going to find.
370 * so we create this discovered_devs model which is similar to a linked-list
371 * which grows when required. it can be freed once discovery has completed,
372 * eliminating the need for a list node in the libusb_device structure
374 struct discovered_devs {
377 struct libusb_device *devices[0];
380 struct discovered_devs *discovered_devs_append(
381 struct discovered_devs *discdevs, struct libusb_device *dev);
385 /* This is the interface that OS backends need to implement.
386 * All fields are mandatory, except ones explicitly noted as optional. */
387 struct usbi_os_backend {
388 /* A human-readable name for your backend, e.g. "Linux usbfs" */
391 /* Perform initialization of your backend. You might use this function
392 * to determine specific capabilities of the system, allocate required
393 * data structures for later, etc.
395 * This function is called when a libusb user initializes the library
398 * Return 0 on success, or a LIBUSB_ERROR code on failure.
400 int (*init)(struct libusb_context *ctx);
402 /* Deinitialization. Optional. This function should destroy anything
403 * that was set up by init.
405 * This function is called when the user deinitializes the library.
409 /* Enumerate all the USB devices on the system, returning them in a list
410 * of discovered devices.
412 * Your implementation should enumerate all devices on the system,
413 * regardless of whether they have been seen before or not.
415 * When you have found a device, compute a session ID for it. The session
416 * ID should uniquely represent that particular device for that particular
417 * connection session since boot (i.e. if you disconnect and reconnect a
418 * device immediately after, it should be assigned a different session ID).
419 * If your OS cannot provide a unique session ID as described above,
420 * presenting a session ID of (bus_number << 8 | device_address) should
421 * be sufficient. Bus numbers and device addresses wrap and get reused,
422 * but that is an unlikely case.
424 * After computing a session ID for a device, call
425 * usbi_get_device_by_session_id(). This function checks if libusb already
426 * knows about the device, and if so, it provides you with a libusb_device
429 * If usbi_get_device_by_session_id() returns NULL, it is time to allocate
430 * a new device structure for the device. Call usbi_alloc_device() to
431 * obtain a new libusb_device structure with reference count 1. Populate
432 * the bus_number and device_address attributes of the new device, and
433 * perform any other internal backend initialization you need to do. At
434 * this point, you should be ready to provide device descriptors and so
435 * on through the get_*_descriptor functions. Finally, call
436 * usbi_sanitize_device() to perform some final sanity checks on the
437 * device. Assuming all of the above succeeded, we can now continue.
438 * If any of the above failed, remember to unreference the device that
439 * was returned by usbi_alloc_device().
441 * At this stage we have a populated libusb_device structure (either one
442 * that was found earlier, or one that we have just allocated and
443 * populated). This can now be added to the discovered devices list
444 * using discovered_devs_append(). Note that discovered_devs_append()
445 * may reallocate the list, returning a new location for it, and also
446 * note that reallocation can fail. Your backend should handle these
447 * error conditions appropriately.
449 * This function should not generate any bus I/O and should not block.
450 * If I/O is required (e.g. reading the active configuration value), it is
451 * OK to ignore these suggestions :)
453 * This function is executed when the user wishes to retrieve a list
454 * of USB devices connected to the system.
456 * Return 0 on success, or a LIBUSB_ERROR code on failure.
458 int (*get_device_list)(struct libusb_context *ctx,
459 struct discovered_devs **discdevs);
461 /* Open a device for I/O and other USB operations. The device handle
462 * is preallocated for you, you can retrieve the device in question
463 * through handle->dev.
465 * Your backend should allocate any internal resources required for I/O
466 * and other operations so that those operations can happen (hopefully)
467 * without hiccup. This is also a good place to inform libusb that it
468 * should monitor certain file descriptors related to this device -
469 * see the usbi_add_pollfd() function.
471 * This function should not generate any bus I/O and should not block.
473 * This function is called when the user attempts to obtain a device
474 * handle for a device.
478 * - LIBUSB_ERROR_ACCESS if the user has insufficient permissions
479 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since
481 * - another LIBUSB_ERROR code on other failure
483 * Do not worry about freeing the handle on failed open, the upper layers
486 int (*open)(struct libusb_device_handle *handle);
488 /* Close a device such that the handle cannot be used again. Your backend
489 * should destroy any resources that were allocated in the open path.
490 * This may also be a good place to call usbi_remove_pollfd() to inform
491 * libusb of any file descriptors associated with this device that should
492 * no longer be monitored.
494 * This function is called when the user closes a device handle.
496 void (*close)(struct libusb_device_handle *handle);
498 /* Retrieve the device descriptor from a device.
500 * The descriptor should be retrieved from memory, NOT via bus I/O to the
501 * device. This means that you may have to cache it in a private structure
502 * during get_device_list enumeration. Alternatively, you may be able
503 * to retrieve it from a kernel interface (some Linux setups can do this)
504 * still without generating bus I/O.
506 * This function is expected to write DEVICE_DESC_LENGTH (18) bytes into
507 * buffer, which is guaranteed to be big enough.
509 * This function is called when sanity-checking a device before adding
510 * it to the list of discovered devices, and also when the user requests
511 * to read the device descriptor.
513 * This function is expected to return the descriptor in bus-endian format
514 * (LE). If it returns the multi-byte values in host-endian format,
515 * set the host_endian output parameter to "1".
517 * Return 0 on success or a LIBUSB_ERROR code on failure.
519 int (*get_device_descriptor)(struct libusb_device *device,
520 unsigned char *buffer, int *host_endian);
522 /* Get the ACTIVE configuration descriptor for 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. You may also have to keep track
527 * of which configuration is active when the user changes it.
529 * This function is expected to write len bytes of data into buffer, which
530 * is guaranteed to be big enough. If you can only do a partial write,
531 * return an error code.
533 * This function is expected to return the descriptor in bus-endian format
534 * (LE). If it returns the multi-byte values in host-endian format,
535 * set the host_endian output parameter to "1".
539 * - LIBUSB_ERROR_NOT_FOUND if the device is in unconfigured state
540 * - another LIBUSB_ERROR code on other failure
542 int (*get_active_config_descriptor)(struct libusb_device *device,
543 unsigned char *buffer, size_t len, int *host_endian);
545 /* Get a specific configuration descriptor for a device.
547 * The descriptor should be retrieved from memory, NOT via bus I/O to the
548 * device. This means that you may have to cache it in a private structure
549 * during get_device_list enumeration.
551 * The requested descriptor is expressed as a zero-based index (i.e. 0
552 * indicates that we are requesting the first descriptor). The index does
553 * not (necessarily) equal the bConfigurationValue of the configuration
556 * This function is expected to write len bytes of data into buffer, which
557 * is guaranteed to be big enough. If you can only do a partial write,
558 * return an error code.
560 * This function is expected to return the descriptor in bus-endian format
561 * (LE). If it returns the multi-byte values in host-endian format,
562 * set the host_endian output parameter to "1".
564 * Return 0 on success or a LIBUSB_ERROR code on failure.
566 int (*get_config_descriptor)(struct libusb_device *device,
567 uint8_t config_index, unsigned char *buffer, size_t len,
570 /* Get the bConfigurationValue for the active configuration for a device.
571 * Optional. This should only be implemented if you can retrieve it from
572 * cache (don't generate I/O).
574 * If you cannot retrieve this from cache, either do not implement this
575 * function, or return LIBUSB_ERROR_NOT_SUPPORTED. This will cause
576 * libusb to retrieve the information through a standard control transfer.
578 * This function must be non-blocking.
581 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
583 * - LIBUSB_ERROR_NOT_SUPPORTED if the value cannot be retrieved without
585 * - another LIBUSB_ERROR code on other failure.
587 int (*get_configuration)(struct libusb_device_handle *handle, int *config);
589 /* Set the active configuration for a device.
591 * A configuration value of -1 should put the device in unconfigured state.
593 * This function can block.
597 * - LIBUSB_ERROR_NOT_FOUND if the configuration does not exist
598 * - LIBUSB_ERROR_BUSY if interfaces are currently claimed (and hence
599 * configuration cannot be changed)
600 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
602 * - another LIBUSB_ERROR code on other failure.
604 int (*set_configuration)(struct libusb_device_handle *handle, int config);
606 /* Claim an interface. When claimed, the application can then perform
607 * I/O to an interface's endpoints.
609 * This function should not generate any bus I/O and should not block.
610 * Interface claiming is a logical operation that simply ensures that
611 * no other drivers/applications are using the interface, and after
612 * claiming, no other drivers/applicatiosn can use the interface because
617 * - LIBUSB_ERROR_NOT_FOUND if the interface does not exist
618 * - LIBUSB_ERROR_BUSY if the interface is in use by another driver/app
619 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
621 * - another LIBUSB_ERROR code on other failure
623 int (*claim_interface)(struct libusb_device_handle *handle, int interface_number);
625 /* Release a previously claimed interface.
627 * This function should also generate a SET_INTERFACE control request,
628 * resetting the alternate setting of that interface to 0. It's OK for
629 * this function to block as a result.
631 * You will only ever be asked to release an interface which was
632 * successfully claimed earlier.
636 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
638 * - another LIBUSB_ERROR code on other failure
640 int (*release_interface)(struct libusb_device_handle *handle, int interface_number);
642 /* Set the alternate setting for an interface.
644 * You will only ever be asked to set the alternate setting for an
645 * interface which was successfully claimed earlier.
647 * It's OK for this function to block.
651 * - LIBUSB_ERROR_NOT_FOUND if the alternate setting does not exist
652 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
654 * - another LIBUSB_ERROR code on other failure
656 int (*set_interface_altsetting)(struct libusb_device_handle *handle,
657 int interface_number, int altsetting);
659 /* Clear a halt/stall condition on an endpoint.
661 * It's OK for this function to block.
665 * - LIBUSB_ERROR_NOT_FOUND if the endpoint does not exist
666 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
668 * - another LIBUSB_ERROR code on other failure
670 int (*clear_halt)(struct libusb_device_handle *handle,
671 unsigned char endpoint);
673 /* Perform a USB port reset to reinitialize a device.
675 * If possible, the handle should still be usable after the reset
676 * completes, assuming that the device descriptors did not change during
677 * reset and all previous interface state can be restored.
679 * If something changes, or you cannot easily locate/verify the resetted
680 * device, return LIBUSB_ERROR_NOT_FOUND. This prompts the application
681 * to close the old handle and re-enumerate the device.
685 * - LIBUSB_ERROR_NOT_FOUND if re-enumeration is required, or if the device
686 * has been disconnected since it was opened
687 * - another LIBUSB_ERROR code on other failure
689 int (*reset_device)(struct libusb_device_handle *handle);
691 /* Determine if a kernel driver is active on an interface. Optional.
693 * The presence of a kernel driver on an interface indicates that any
694 * calls to claim_interface would fail with the LIBUSB_ERROR_BUSY code.
697 * - 0 if no driver is active
698 * - 1 if a driver is active
699 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
701 * - another LIBUSB_ERROR code on other failure
703 int (*kernel_driver_active)(struct libusb_device_handle *handle,
704 int interface_number);
706 /* Detach a kernel driver from an interface. Optional.
708 * After detaching a kernel driver, the interface should be available
713 * - LIBUSB_ERROR_NOT_FOUND if no kernel driver was active
714 * - LIBUSB_ERROR_INVALID_PARAM if the interface does not exist
715 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
717 * - another LIBUSB_ERROR code on other failure
719 int (*detach_kernel_driver)(struct libusb_device_handle *handle,
720 int interface_number);
722 /* Attach a kernel driver to an interface. Optional.
724 * Reattach a kernel driver to the device.
728 * - LIBUSB_ERROR_NOT_FOUND if no kernel driver was active
729 * - LIBUSB_ERROR_INVALID_PARAM if the interface does not exist
730 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
732 * - LIBUSB_ERROR_BUSY if a program or driver has claimed the interface,
733 * preventing reattachment
734 * - another LIBUSB_ERROR code on other failure
736 int (*attach_kernel_driver)(struct libusb_device_handle *handle,
737 int interface_number);
739 /* Destroy a device. Optional.
741 * This function is called when the last reference to a device is
742 * destroyed. It should free any resources allocated in the get_device_list
745 void (*destroy_device)(struct libusb_device *dev);
747 /* Submit a transfer. Your implementation should take the transfer,
748 * morph it into whatever form your platform requires, and submit it
751 * This function must not block.
755 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
756 * - another LIBUSB_ERROR code on other failure
758 int (*submit_transfer)(struct usbi_transfer *itransfer);
760 /* Cancel a previously submitted transfer.
762 * This function must not block. The transfer cancellation must complete
763 * later, resulting in a call to usbi_handle_transfer_cancellation()
764 * from the context of handle_events.
766 int (*cancel_transfer)(struct usbi_transfer *itransfer);
768 /* Clear a transfer as if it has completed or cancelled, but do not
769 * report any completion/cancellation to the library. You should free
770 * all private data from the transfer as if you were just about to report
771 * completion or cancellation.
773 * This function might seem a bit out of place. It is used when libusb
774 * detects a disconnected device - it calls this function for all pending
775 * transfers before reporting completion (with the disconnect code) to
776 * the user. Maybe we can improve upon this internal interface in future.
778 void (*clear_transfer_priv)(struct usbi_transfer *itransfer);
780 /* Handle any pending events. This involves monitoring any active
781 * transfers and processing their completion or cancellation.
783 * The function is passed an array of pollfd structures (size nfds)
784 * as a result of the poll() system call. The num_ready parameter
785 * indicates the number of file descriptors that have reported events
786 * (i.e. the poll() return value). This should be enough information
787 * for you to determine which actions need to be taken on the currently
790 * For any cancelled transfers, call usbi_handle_transfer_cancellation().
791 * For completed transfers, call usbi_handle_transfer_completion().
792 * For control/bulk/interrupt transfers, populate the "transferred"
793 * element of the appropriate usbi_transfer structure before calling the
794 * above functions. For isochronous transfers, populate the status and
795 * transferred fields of the iso packet descriptors of the transfer.
797 * This function should also be able to detect disconnection of the
798 * device, reporting that situation with usbi_handle_disconnect().
800 * When processing an event related to a transfer, you probably want to
801 * take usbi_transfer.lock to prevent races. See the documentation for
802 * the usbi_transfer structure.
804 * Return 0 on success, or a LIBUSB_ERROR code on failure.
806 int (*handle_events)(struct libusb_context *ctx,
807 struct pollfd *fds, nfds_t nfds, int num_ready);
809 /* Get time from specified clock. At least two clocks must be implemented
810 by the backend: USBI_CLOCK_REALTIME, and USBI_CLOCK_MONOTONIC.
812 Description of clocks:
813 USBI_CLOCK_REALTIME : clock returns time since system epoch.
814 USBI_CLOCK_MONOTONIC: clock returns time since unspecified start
817 int (*clock_gettime)(int clkid, struct timespec *tp);
819 #ifdef USBI_TIMERFD_AVAILABLE
820 /* clock ID of the clock that should be used for timerfd */
821 clockid_t (*get_timerfd_clockid)(void);
824 /* Number of bytes to reserve for per-device private backend data.
825 * This private data area is accessible through the "os_priv" field of
826 * struct libusb_device. */
827 size_t device_priv_size;
829 /* Number of bytes to reserve for per-handle private backend data.
830 * This private data area is accessible through the "os_priv" field of
831 * struct libusb_device. */
832 size_t device_handle_priv_size;
834 /* Number of bytes to reserve for per-transfer private backend data.
835 * This private data area is accessible by calling
836 * usbi_transfer_get_os_priv() on the appropriate usbi_transfer instance.
838 size_t transfer_priv_size;
840 /* Mumber of additional bytes for os_priv for each iso packet.
841 * Can your backend use this? */
842 /* FIXME: linux can't use this any more. if other OS's cannot either,
843 * then remove this */
844 size_t add_iso_packet_size;
847 extern const struct usbi_os_backend * const usbi_backend;
849 extern const struct usbi_os_backend linux_usbfs_backend;
850 extern const struct usbi_os_backend darwin_backend;