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
36 /* Inside the libusb code, mark all public functions as follows:
37 * return_type API_EXPORTED function_name(params) { ... }
38 * But if the function returns a pointer, mark it as follows:
39 * DEFAULT_VISIBILITY return_type * LIBUSB_CALL function_name(params) { ... }
40 * In the libusb public header, mark all declarations as:
41 * return_type LIBUSB_CALL function_name(params);
43 #define API_EXPORTED LIBUSB_CALL DEFAULT_VISIBILITY
45 #define DEVICE_DESC_LENGTH 18
47 #define USB_MAXENDPOINTS 32
48 #define USB_MAXINTERFACES 32
49 #define USB_MAXCONFIG 8
52 struct list_head *prev, *next;
55 /* Get an entry from the list
56 * ptr - the address of this list_head element in "type"
57 * type - the data type that contains "member"
58 * member - the list_head element in "type"
60 #define list_entry(ptr, type, member) \
61 ((type *)((uintptr_t)(ptr) - (uintptr_t)(&((type *)0L)->member)))
63 /* Get each entry from a list
64 * pos - A structure pointer has a "member" element
66 * member - the list_head element in "pos"
67 * type - the type of the first parameter
69 #define list_for_each_entry(pos, head, member, type) \
70 for (pos = list_entry((head)->next, type, member); \
71 &pos->member != (head); \
72 pos = list_entry(pos->member.next, type, member))
74 #define list_for_each_entry_safe(pos, n, head, member, type) \
75 for (pos = list_entry((head)->next, type, member), \
76 n = list_entry(pos->member.next, type, member); \
77 &pos->member != (head); \
78 pos = n, n = list_entry(n->member.next, type, member))
80 #define list_empty(entry) ((entry)->next == (entry))
82 static inline void list_init(struct list_head *entry)
84 entry->prev = entry->next = entry;
87 static inline void list_add(struct list_head *entry, struct list_head *head)
89 entry->next = head->next;
92 head->next->prev = entry;
96 static inline void list_add_tail(struct list_head *entry,
97 struct list_head *head)
100 entry->prev = head->prev;
102 head->prev->next = entry;
106 static inline void list_del(struct list_head *entry)
108 entry->next->prev = entry->prev;
109 entry->prev->next = entry->next;
112 #define container_of(ptr, type, member) ({ \
113 const typeof( ((type *)0)->member ) *mptr = (ptr); \
114 (type *)( (char *)mptr - offsetof(type,member) );})
116 #define MIN(a, b) ((a) < (b) ? (a) : (b))
117 #define MAX(a, b) ((a) > (b) ? (a) : (b))
119 #define TIMESPEC_IS_SET(ts) ((ts)->tv_sec != 0 || (ts)->tv_nsec != 0)
121 enum usbi_log_level {
128 void usbi_log(struct libusb_context *ctx, enum usbi_log_level level,
129 const char *function, const char *format, ...);
131 void usbi_log_v(struct libusb_context *ctx, enum usbi_log_level level,
132 const char *function, const char *format, va_list args);
134 #if !defined(_MSC_VER) || _MSC_VER > 1200
136 #ifdef ENABLE_LOGGING
137 #define _usbi_log(ctx, level, ...) usbi_log(ctx, level, __FUNCTION__, __VA_ARGS__)
139 #define _usbi_log(ctx, level, ...) do { (void)(ctx); } while(0)
142 #ifdef ENABLE_DEBUG_LOGGING
143 #define usbi_dbg(...) _usbi_log(NULL, LOG_LEVEL_DEBUG, __VA_ARGS__)
145 #define usbi_dbg(...) do {} while(0)
148 #define usbi_info(ctx, ...) _usbi_log(ctx, LOG_LEVEL_INFO, __VA_ARGS__)
149 #define usbi_warn(ctx, ...) _usbi_log(ctx, LOG_LEVEL_WARNING, __VA_ARGS__)
150 #define usbi_err(ctx, ...) _usbi_log(ctx, LOG_LEVEL_ERROR, __VA_ARGS__)
152 #else /* !defined(_MSC_VER) || _MSC_VER > 1200 */
154 #ifdef ENABLE_LOGGING
155 #define LOG_BODY(ctxt, level) \
158 va_start (args, format); \
159 usbi_log_v(ctxt, level, "", format, args); \
163 #define LOG_BODY(ctxt, level) do { (void)(ctxt); } while(0)
166 static inline void usbi_info(struct libusb_context *ctx, const char *format,
168 LOG_BODY(ctx,LOG_LEVEL_INFO)
169 static inline void usbi_warn(struct libusb_context *ctx, const char *format,
171 LOG_BODY(ctx,LOG_LEVEL_WARNING)
172 static inline void usbi_err( struct libusb_context *ctx, const char *format,
174 LOG_BODY(ctx,LOG_LEVEL_ERROR)
176 static inline void usbi_dbg(const char *format, ...)
177 #ifdef ENABLE_DEBUG_LOGGING
178 LOG_BODY(NULL,LOG_LEVEL_DEBUG)
183 #endif /* !defined(_MSC_VER) || _MSC_VER > 1200 */
185 #define USBI_GET_CONTEXT(ctx) if (!(ctx)) (ctx) = usbi_default_context
186 #define DEVICE_CTX(dev) ((dev)->ctx)
187 #define HANDLE_CTX(handle) (DEVICE_CTX((handle)->dev))
188 #define TRANSFER_CTX(transfer) (HANDLE_CTX((transfer)->dev_handle))
189 #define ITRANSFER_CTX(transfer) \
190 (TRANSFER_CTX(USBI_TRANSFER_TO_LIBUSB_TRANSFER(transfer)))
192 /* Internal abstractions for thread synchronization and poll */
193 #if defined(THREADS_POSIX)
194 #include <os/threads_posix.h>
195 #elif defined(OS_WINDOWS)
196 #include <os/threads_windows.h>
199 #if defined(OS_LINUX) || defined(OS_DARWIN) || defined(OS_OPENBSD)
201 #include <os/poll_posix.h>
202 #elif defined(OS_WINDOWS)
203 #include <os/poll_windows.h>
206 extern struct libusb_context *usbi_default_context;
208 struct libusb_context {
212 /* internal control pipe, used for interrupting event handling when
213 * something needs to modify poll fds. */
216 struct list_head usb_devs;
217 usbi_mutex_t usb_devs_lock;
219 /* A list of open handles. Backends are free to traverse this if required.
221 struct list_head open_devs;
222 usbi_mutex_t open_devs_lock;
224 /* this is a list of in-flight transfer handles, sorted by timeout
225 * expiration. URBs to timeout the soonest are placed at the beginning of
226 * the list, URBs that will time out later are placed after, and urbs with
227 * infinite timeout are always placed at the very end. */
228 struct list_head flying_transfers;
229 usbi_mutex_t flying_transfers_lock;
231 /* list of poll fds */
232 struct list_head pollfds;
233 usbi_mutex_t pollfds_lock;
235 /* a counter that is set when we want to interrupt event handling, in order
236 * to modify the poll fd set. and a lock to protect it. */
237 unsigned int pollfd_modify;
238 usbi_mutex_t pollfd_modify_lock;
240 /* user callbacks for pollfd changes */
241 libusb_pollfd_added_cb fd_added_cb;
242 libusb_pollfd_removed_cb fd_removed_cb;
243 void *fd_cb_user_data;
245 /* ensures that only one thread is handling events at any one time */
246 usbi_mutex_t events_lock;
248 /* used to see if there is an active thread doing event handling */
249 int event_handler_active;
251 /* used to wait for event completion in threads other than the one that is
253 usbi_mutex_t event_waiters_lock;
254 usbi_cond_t event_waiters_cond;
256 #ifdef USBI_TIMERFD_AVAILABLE
257 /* used for timeout handling, if supported by OS.
258 * this timerfd is maintained to trigger on the next pending timeout */
263 #ifdef USBI_TIMERFD_AVAILABLE
264 #define usbi_using_timerfd(ctx) ((ctx)->timerfd >= 0)
266 #define usbi_using_timerfd(ctx) (0)
269 struct libusb_device {
270 /* lock protects refcnt, everything else is finalized at initialization
275 struct libusb_context *ctx;
278 uint8_t device_address;
279 uint8_t num_configurations;
280 enum libusb_speed speed;
282 struct list_head list;
283 unsigned long session_data;
284 unsigned char os_priv[0];
287 struct libusb_device_handle {
288 /* lock protects claimed_interfaces */
290 unsigned long claimed_interfaces;
292 struct list_head list;
293 struct libusb_device *dev;
294 unsigned char os_priv[0];
298 USBI_CLOCK_MONOTONIC,
302 /* in-memory transfer layout:
304 * 1. struct usbi_transfer
305 * 2. struct libusb_transfer (which includes iso packets) [variable size]
306 * 3. os private data [variable size]
308 * from a libusb_transfer, you can get the usbi_transfer by rewinding the
309 * appropriate number of bytes.
310 * the usbi_transfer includes the number of allocated packets, so you can
311 * determine the size of the transfer and hence the start and length of the
315 struct usbi_transfer {
317 struct list_head list;
318 struct timeval timeout;
322 /* this lock is held during libusb_submit_transfer() and
323 * libusb_cancel_transfer() (allowing the OS backend to prevent duplicate
324 * cancellation, submission-during-cancellation, etc). the OS backend
325 * should also take this lock in the handle_events path, to prevent the user
326 * cancelling the transfer from another thread while you are processing
327 * its completion (presumably there would be races within your OS backend
328 * if this were possible). */
332 enum usbi_transfer_flags {
333 /* The transfer has timed out */
334 USBI_TRANSFER_TIMED_OUT = 1 << 0,
336 /* Set by backend submit_transfer() if the OS handles timeout */
337 USBI_TRANSFER_OS_HANDLES_TIMEOUT = 1 << 1,
339 /* Cancellation was requested via libusb_cancel_transfer() */
340 USBI_TRANSFER_CANCELLING = 1 << 2,
342 /* Operation on the transfer failed because the device disappeared */
343 USBI_TRANSFER_DEVICE_DISAPPEARED = 1 << 3,
346 #define USBI_TRANSFER_TO_LIBUSB_TRANSFER(transfer) \
347 ((struct libusb_transfer *)(((unsigned char *)(transfer)) \
348 + sizeof(struct usbi_transfer)))
349 #define LIBUSB_TRANSFER_TO_USBI_TRANSFER(transfer) \
350 ((struct usbi_transfer *)(((unsigned char *)(transfer)) \
351 - sizeof(struct usbi_transfer)))
353 static inline void *usbi_transfer_get_os_priv(struct usbi_transfer *transfer)
355 return ((unsigned char *)transfer) + sizeof(struct usbi_transfer)
356 + sizeof(struct libusb_transfer)
357 + (transfer->num_iso_packets
358 * sizeof(struct libusb_iso_packet_descriptor));
363 /* All standard descriptors have these 2 fields in common */
364 struct usb_descriptor_header {
366 uint8_t bDescriptorType;
369 /* shared data and functions */
371 int usbi_io_init(struct libusb_context *ctx);
372 void usbi_io_exit(struct libusb_context *ctx);
374 struct libusb_device *usbi_alloc_device(struct libusb_context *ctx,
375 unsigned long session_id);
376 struct libusb_device *usbi_get_device_by_session_id(struct libusb_context *ctx,
377 unsigned long session_id);
378 int usbi_sanitize_device(struct libusb_device *dev);
379 void usbi_handle_disconnect(struct libusb_device_handle *handle);
381 int usbi_handle_transfer_completion(struct usbi_transfer *itransfer,
382 enum libusb_transfer_status status);
383 int usbi_handle_transfer_cancellation(struct usbi_transfer *transfer);
385 int usbi_parse_descriptor(unsigned char *source, const char *descriptor,
386 void *dest, int host_endian);
387 int usbi_get_config_index_by_value(struct libusb_device *dev,
388 uint8_t bConfigurationValue, int *idx);
393 /* must come first */
394 struct libusb_pollfd pollfd;
396 struct list_head list;
399 int usbi_add_pollfd(struct libusb_context *ctx, int fd, short events);
400 void usbi_remove_pollfd(struct libusb_context *ctx, int fd);
401 void usbi_fd_notification(struct libusb_context *ctx);
403 /* device discovery */
405 /* we traverse usbfs without knowing how many devices we are going to find.
406 * so we create this discovered_devs model which is similar to a linked-list
407 * which grows when required. it can be freed once discovery has completed,
408 * eliminating the need for a list node in the libusb_device structure
410 struct discovered_devs {
413 struct libusb_device *devices[0];
416 struct discovered_devs *discovered_devs_append(
417 struct discovered_devs *discdevs, struct libusb_device *dev);
421 /* This is the interface that OS backends need to implement.
422 * All fields are mandatory, except ones explicitly noted as optional. */
423 struct usbi_os_backend {
424 /* A human-readable name for your backend, e.g. "Linux usbfs" */
427 /* Perform initialization of your backend. You might use this function
428 * to determine specific capabilities of the system, allocate required
429 * data structures for later, etc.
431 * This function is called when a libusb user initializes the library
434 * Return 0 on success, or a LIBUSB_ERROR code on failure.
436 int (*init)(struct libusb_context *ctx);
438 /* Deinitialization. Optional. This function should destroy anything
439 * that was set up by init.
441 * This function is called when the user deinitializes the library.
445 /* Enumerate all the USB devices on the system, returning them in a list
446 * of discovered devices.
448 * Your implementation should enumerate all devices on the system,
449 * regardless of whether they have been seen before or not.
451 * When you have found a device, compute a session ID for it. The session
452 * ID should uniquely represent that particular device for that particular
453 * connection session since boot (i.e. if you disconnect and reconnect a
454 * device immediately after, it should be assigned a different session ID).
455 * If your OS cannot provide a unique session ID as described above,
456 * presenting a session ID of (bus_number << 8 | device_address) should
457 * be sufficient. Bus numbers and device addresses wrap and get reused,
458 * but that is an unlikely case.
460 * After computing a session ID for a device, call
461 * usbi_get_device_by_session_id(). This function checks if libusb already
462 * knows about the device, and if so, it provides you with a libusb_device
465 * If usbi_get_device_by_session_id() returns NULL, it is time to allocate
466 * a new device structure for the device. Call usbi_alloc_device() to
467 * obtain a new libusb_device structure with reference count 1. Populate
468 * the bus_number and device_address attributes of the new device, and
469 * perform any other internal backend initialization you need to do. At
470 * this point, you should be ready to provide device descriptors and so
471 * on through the get_*_descriptor functions. Finally, call
472 * usbi_sanitize_device() to perform some final sanity checks on the
473 * device. Assuming all of the above succeeded, we can now continue.
474 * If any of the above failed, remember to unreference the device that
475 * was returned by usbi_alloc_device().
477 * At this stage we have a populated libusb_device structure (either one
478 * that was found earlier, or one that we have just allocated and
479 * populated). This can now be added to the discovered devices list
480 * using discovered_devs_append(). Note that discovered_devs_append()
481 * may reallocate the list, returning a new location for it, and also
482 * note that reallocation can fail. Your backend should handle these
483 * error conditions appropriately.
485 * This function should not generate any bus I/O and should not block.
486 * If I/O is required (e.g. reading the active configuration value), it is
487 * OK to ignore these suggestions :)
489 * This function is executed when the user wishes to retrieve a list
490 * of USB devices connected to the system.
492 * Return 0 on success, or a LIBUSB_ERROR code on failure.
494 int (*get_device_list)(struct libusb_context *ctx,
495 struct discovered_devs **discdevs);
497 /* Open a device for I/O and other USB operations. The device handle
498 * is preallocated for you, you can retrieve the device in question
499 * through handle->dev.
501 * Your backend should allocate any internal resources required for I/O
502 * and other operations so that those operations can happen (hopefully)
503 * without hiccup. This is also a good place to inform libusb that it
504 * should monitor certain file descriptors related to this device -
505 * see the usbi_add_pollfd() function.
507 * This function should not generate any bus I/O and should not block.
509 * This function is called when the user attempts to obtain a device
510 * handle for a device.
514 * - LIBUSB_ERROR_ACCESS if the user has insufficient permissions
515 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since
517 * - another LIBUSB_ERROR code on other failure
519 * Do not worry about freeing the handle on failed open, the upper layers
522 int (*open)(struct libusb_device_handle *handle);
524 /* Close a device such that the handle cannot be used again. Your backend
525 * should destroy any resources that were allocated in the open path.
526 * This may also be a good place to call usbi_remove_pollfd() to inform
527 * libusb of any file descriptors associated with this device that should
528 * no longer be monitored.
530 * This function is called when the user closes a device handle.
532 void (*close)(struct libusb_device_handle *handle);
534 /* Retrieve the device descriptor from a device.
536 * The descriptor should be retrieved from memory, NOT via bus I/O to the
537 * device. This means that you may have to cache it in a private structure
538 * during get_device_list enumeration. Alternatively, you may be able
539 * to retrieve it from a kernel interface (some Linux setups can do this)
540 * still without generating bus I/O.
542 * This function is expected to write DEVICE_DESC_LENGTH (18) bytes into
543 * buffer, which is guaranteed to be big enough.
545 * This function is called when sanity-checking a device before adding
546 * it to the list of discovered devices, and also when the user requests
547 * to read the device descriptor.
549 * This function is expected to return the descriptor in bus-endian format
550 * (LE). If it returns the multi-byte values in host-endian format,
551 * set the host_endian output parameter to "1".
553 * Return 0 on success or a LIBUSB_ERROR code on failure.
555 int (*get_device_descriptor)(struct libusb_device *device,
556 unsigned char *buffer, int *host_endian);
558 /* Get the ACTIVE configuration descriptor for a device.
560 * The descriptor should be retrieved from memory, NOT via bus I/O to the
561 * device. This means that you may have to cache it in a private structure
562 * during get_device_list enumeration. You may also have to keep track
563 * of which configuration is active when the user changes it.
565 * This function is expected to write len bytes of data into buffer, which
566 * is guaranteed to be big enough. If you can only do a partial write,
567 * return an error code.
569 * This function is expected to return the descriptor in bus-endian format
570 * (LE). If it returns the multi-byte values in host-endian format,
571 * set the host_endian output parameter to "1".
575 * - LIBUSB_ERROR_NOT_FOUND if the device is in unconfigured state
576 * - another LIBUSB_ERROR code on other failure
578 int (*get_active_config_descriptor)(struct libusb_device *device,
579 unsigned char *buffer, size_t len, int *host_endian);
581 /* Get a specific 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.
587 * The requested descriptor is expressed as a zero-based index (i.e. 0
588 * indicates that we are requesting the first descriptor). The index does
589 * not (necessarily) equal the bConfigurationValue of the configuration
592 * This function is expected to write len bytes of data into buffer, which
593 * is guaranteed to be big enough. If you can only do a partial write,
594 * return an error code.
596 * This function is expected to return the descriptor in bus-endian format
597 * (LE). If it returns the multi-byte values in host-endian format,
598 * set the host_endian output parameter to "1".
600 * Return 0 on success or a LIBUSB_ERROR code on failure.
602 int (*get_config_descriptor)(struct libusb_device *device,
603 uint8_t config_index, unsigned char *buffer, size_t len,
606 /* Get the bConfigurationValue for the active configuration for a device.
607 * Optional. This should only be implemented if you can retrieve it from
608 * cache (don't generate I/O).
610 * If you cannot retrieve this from cache, either do not implement this
611 * function, or return LIBUSB_ERROR_NOT_SUPPORTED. This will cause
612 * libusb to retrieve the information through a standard control transfer.
614 * This function must be non-blocking.
617 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
619 * - LIBUSB_ERROR_NOT_SUPPORTED if the value cannot be retrieved without
621 * - another LIBUSB_ERROR code on other failure.
623 int (*get_configuration)(struct libusb_device_handle *handle, int *config);
625 /* Set the active configuration for a device.
627 * A configuration value of -1 should put the device in unconfigured state.
629 * This function can block.
633 * - LIBUSB_ERROR_NOT_FOUND if the configuration does not exist
634 * - LIBUSB_ERROR_BUSY if interfaces are currently claimed (and hence
635 * configuration cannot be changed)
636 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
638 * - another LIBUSB_ERROR code on other failure.
640 int (*set_configuration)(struct libusb_device_handle *handle, int config);
642 /* Claim an interface. When claimed, the application can then perform
643 * I/O to an interface's endpoints.
645 * This function should not generate any bus I/O and should not block.
646 * Interface claiming is a logical operation that simply ensures that
647 * no other drivers/applications are using the interface, and after
648 * claiming, no other drivers/applicatiosn can use the interface because
653 * - LIBUSB_ERROR_NOT_FOUND if the interface does not exist
654 * - LIBUSB_ERROR_BUSY if the interface is in use by another driver/app
655 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
657 * - another LIBUSB_ERROR code on other failure
659 int (*claim_interface)(struct libusb_device_handle *handle, int interface_number);
661 /* Release a previously claimed interface.
663 * This function should also generate a SET_INTERFACE control request,
664 * resetting the alternate setting of that interface to 0. It's OK for
665 * this function to block as a result.
667 * You will only ever be asked to release an interface which was
668 * successfully claimed earlier.
672 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
674 * - another LIBUSB_ERROR code on other failure
676 int (*release_interface)(struct libusb_device_handle *handle, int interface_number);
678 /* Set the alternate setting for an interface.
680 * You will only ever be asked to set the alternate setting for an
681 * interface which was successfully claimed earlier.
683 * It's OK for this function to block.
687 * - LIBUSB_ERROR_NOT_FOUND if the alternate setting does not exist
688 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
690 * - another LIBUSB_ERROR code on other failure
692 int (*set_interface_altsetting)(struct libusb_device_handle *handle,
693 int interface_number, int altsetting);
695 /* Clear a halt/stall condition on an endpoint.
697 * It's OK for this function to block.
701 * - LIBUSB_ERROR_NOT_FOUND if the endpoint does not exist
702 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
704 * - another LIBUSB_ERROR code on other failure
706 int (*clear_halt)(struct libusb_device_handle *handle,
707 unsigned char endpoint);
709 /* Perform a USB port reset to reinitialize a device.
711 * If possible, the handle should still be usable after the reset
712 * completes, assuming that the device descriptors did not change during
713 * reset and all previous interface state can be restored.
715 * If something changes, or you cannot easily locate/verify the resetted
716 * device, return LIBUSB_ERROR_NOT_FOUND. This prompts the application
717 * to close the old handle and re-enumerate the device.
721 * - LIBUSB_ERROR_NOT_FOUND if re-enumeration is required, or if the device
722 * has been disconnected since it was opened
723 * - another LIBUSB_ERROR code on other failure
725 int (*reset_device)(struct libusb_device_handle *handle);
727 /* Determine if a kernel driver is active on an interface. Optional.
729 * The presence of a kernel driver on an interface indicates that any
730 * calls to claim_interface would fail with the LIBUSB_ERROR_BUSY code.
733 * - 0 if no driver is active
734 * - 1 if a driver is active
735 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
737 * - another LIBUSB_ERROR code on other failure
739 int (*kernel_driver_active)(struct libusb_device_handle *handle,
740 int interface_number);
742 /* Detach a kernel driver from an interface. Optional.
744 * After detaching a kernel driver, the interface should be available
749 * - LIBUSB_ERROR_NOT_FOUND if no kernel driver was active
750 * - LIBUSB_ERROR_INVALID_PARAM if the interface does not exist
751 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
753 * - another LIBUSB_ERROR code on other failure
755 int (*detach_kernel_driver)(struct libusb_device_handle *handle,
756 int interface_number);
758 /* Attach a kernel driver to an interface. Optional.
760 * Reattach a kernel driver to the device.
764 * - LIBUSB_ERROR_NOT_FOUND if no kernel driver was active
765 * - LIBUSB_ERROR_INVALID_PARAM if the interface does not exist
766 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
768 * - LIBUSB_ERROR_BUSY if a program or driver has claimed the interface,
769 * preventing reattachment
770 * - another LIBUSB_ERROR code on other failure
772 int (*attach_kernel_driver)(struct libusb_device_handle *handle,
773 int interface_number);
775 /* Destroy a device. Optional.
777 * This function is called when the last reference to a device is
778 * destroyed. It should free any resources allocated in the get_device_list
781 void (*destroy_device)(struct libusb_device *dev);
783 /* Submit a transfer. Your implementation should take the transfer,
784 * morph it into whatever form your platform requires, and submit it
787 * This function must not block.
791 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
792 * - another LIBUSB_ERROR code on other failure
794 int (*submit_transfer)(struct usbi_transfer *itransfer);
796 /* Cancel a previously submitted transfer.
798 * This function must not block. The transfer cancellation must complete
799 * later, resulting in a call to usbi_handle_transfer_cancellation()
800 * from the context of handle_events.
802 int (*cancel_transfer)(struct usbi_transfer *itransfer);
804 /* Clear a transfer as if it has completed or cancelled, but do not
805 * report any completion/cancellation to the library. You should free
806 * all private data from the transfer as if you were just about to report
807 * completion or cancellation.
809 * This function might seem a bit out of place. It is used when libusb
810 * detects a disconnected device - it calls this function for all pending
811 * transfers before reporting completion (with the disconnect code) to
812 * the user. Maybe we can improve upon this internal interface in future.
814 void (*clear_transfer_priv)(struct usbi_transfer *itransfer);
816 /* Handle any pending events. This involves monitoring any active
817 * transfers and processing their completion or cancellation.
819 * The function is passed an array of pollfd structures (size nfds)
820 * as a result of the poll() system call. The num_ready parameter
821 * indicates the number of file descriptors that have reported events
822 * (i.e. the poll() return value). This should be enough information
823 * for you to determine which actions need to be taken on the currently
826 * For any cancelled transfers, call usbi_handle_transfer_cancellation().
827 * For completed transfers, call usbi_handle_transfer_completion().
828 * For control/bulk/interrupt transfers, populate the "transferred"
829 * element of the appropriate usbi_transfer structure before calling the
830 * above functions. For isochronous transfers, populate the status and
831 * transferred fields of the iso packet descriptors of the transfer.
833 * This function should also be able to detect disconnection of the
834 * device, reporting that situation with usbi_handle_disconnect().
836 * When processing an event related to a transfer, you probably want to
837 * take usbi_transfer.lock to prevent races. See the documentation for
838 * the usbi_transfer structure.
840 * Return 0 on success, or a LIBUSB_ERROR code on failure.
842 int (*handle_events)(struct libusb_context *ctx,
843 struct pollfd *fds, POLL_NFDS_TYPE nfds, int num_ready);
845 /* Get time from specified clock. At least two clocks must be implemented
846 by the backend: USBI_CLOCK_REALTIME, and USBI_CLOCK_MONOTONIC.
848 Description of clocks:
849 USBI_CLOCK_REALTIME : clock returns time since system epoch.
850 USBI_CLOCK_MONOTONIC: clock returns time since unspecified start
853 int (*clock_gettime)(int clkid, struct timespec *tp);
855 #ifdef USBI_TIMERFD_AVAILABLE
856 /* clock ID of the clock that should be used for timerfd */
857 clockid_t (*get_timerfd_clockid)(void);
860 /* Number of bytes to reserve for per-device private backend data.
861 * This private data area is accessible through the "os_priv" field of
862 * struct libusb_device. */
863 size_t device_priv_size;
865 /* Number of bytes to reserve for per-handle private backend data.
866 * This private data area is accessible through the "os_priv" field of
867 * struct libusb_device. */
868 size_t device_handle_priv_size;
870 /* Number of bytes to reserve for per-transfer private backend data.
871 * This private data area is accessible by calling
872 * usbi_transfer_get_os_priv() on the appropriate usbi_transfer instance.
874 size_t transfer_priv_size;
876 /* Mumber of additional bytes for os_priv for each iso packet.
877 * Can your backend use this? */
878 /* FIXME: linux can't use this any more. if other OS's cannot either,
879 * then remove this */
880 size_t add_iso_packet_size;
883 extern const struct usbi_os_backend * const usbi_backend;
885 extern const struct usbi_os_backend linux_usbfs_backend;
886 extern const struct usbi_os_backend darwin_backend;
887 extern const struct usbi_os_backend openbsd_backend;
888 extern const struct usbi_os_backend windows_backend;