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
36 /* Inside the libusbx 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 libusbx 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 >= 1400
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 >= 1400 */
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 >= 1400 */
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 #define IS_EPIN(ep) (0 != ((ep) & LIBUSB_ENDPOINT_IN))
193 #define IS_EPOUT(ep) (!IS_EPIN(ep))
194 #define IS_XFERIN(xfer) (0 != ((xfer)->endpoint & LIBUSB_ENDPOINT_IN))
195 #define IS_XFEROUT(xfer) (!IS_XFERIN(xfer))
197 /* Internal abstractions for thread synchronization and poll */
198 #if defined(THREADS_POSIX)
199 #include <os/threads_posix.h>
200 #elif defined(OS_WINDOWS)
201 #include <os/threads_windows.h>
204 #if defined(OS_LINUX) || defined(OS_DARWIN) || defined(OS_OPENBSD)
206 #include <os/poll_posix.h>
207 #elif defined(OS_WINDOWS)
208 #include <os/poll_windows.h>
211 extern struct libusb_context *usbi_default_context;
213 struct libusb_context {
217 /* internal control pipe, used for interrupting event handling when
218 * something needs to modify poll fds. */
221 struct list_head usb_devs;
222 usbi_mutex_t usb_devs_lock;
224 /* A list of open handles. Backends are free to traverse this if required.
226 struct list_head open_devs;
227 usbi_mutex_t open_devs_lock;
229 /* this is a list of in-flight transfer handles, sorted by timeout
230 * expiration. URBs to timeout the soonest are placed at the beginning of
231 * the list, URBs that will time out later are placed after, and urbs with
232 * infinite timeout are always placed at the very end. */
233 struct list_head flying_transfers;
234 usbi_mutex_t flying_transfers_lock;
236 /* list of poll fds */
237 struct list_head pollfds;
238 usbi_mutex_t pollfds_lock;
240 /* a counter that is set when we want to interrupt event handling, in order
241 * to modify the poll fd set. and a lock to protect it. */
242 unsigned int pollfd_modify;
243 usbi_mutex_t pollfd_modify_lock;
245 /* user callbacks for pollfd changes */
246 libusb_pollfd_added_cb fd_added_cb;
247 libusb_pollfd_removed_cb fd_removed_cb;
248 void *fd_cb_user_data;
250 /* ensures that only one thread is handling events at any one time */
251 usbi_mutex_t events_lock;
253 /* used to see if there is an active thread doing event handling */
254 int event_handler_active;
256 /* used to wait for event completion in threads other than the one that is
258 usbi_mutex_t event_waiters_lock;
259 usbi_cond_t event_waiters_cond;
261 #ifdef USBI_TIMERFD_AVAILABLE
262 /* used for timeout handling, if supported by OS.
263 * this timerfd is maintained to trigger on the next pending timeout */
268 #ifdef USBI_TIMERFD_AVAILABLE
269 #define usbi_using_timerfd(ctx) ((ctx)->timerfd >= 0)
271 #define usbi_using_timerfd(ctx) (0)
274 struct libusb_device {
275 /* lock protects refcnt, everything else is finalized at initialization
280 struct libusb_context *ctx;
283 uint8_t device_address;
284 uint8_t num_configurations;
285 enum libusb_speed speed;
287 struct list_head list;
288 unsigned long session_data;
289 unsigned char os_priv[0];
292 struct libusb_device_handle {
293 /* lock protects claimed_interfaces */
295 unsigned long claimed_interfaces;
297 struct list_head list;
298 struct libusb_device *dev;
299 unsigned char os_priv[0];
303 USBI_CLOCK_MONOTONIC,
307 /* in-memory transfer layout:
309 * 1. struct usbi_transfer
310 * 2. struct libusb_transfer (which includes iso packets) [variable size]
311 * 3. os private data [variable size]
313 * from a libusb_transfer, you can get the usbi_transfer by rewinding the
314 * appropriate number of bytes.
315 * the usbi_transfer includes the number of allocated packets, so you can
316 * determine the size of the transfer and hence the start and length of the
320 struct usbi_transfer {
322 struct list_head list;
323 struct timeval timeout;
327 /* this lock is held during libusb_submit_transfer() and
328 * libusb_cancel_transfer() (allowing the OS backend to prevent duplicate
329 * cancellation, submission-during-cancellation, etc). the OS backend
330 * should also take this lock in the handle_events path, to prevent the user
331 * cancelling the transfer from another thread while you are processing
332 * its completion (presumably there would be races within your OS backend
333 * if this were possible). */
337 enum usbi_transfer_flags {
338 /* The transfer has timed out */
339 USBI_TRANSFER_TIMED_OUT = 1 << 0,
341 /* Set by backend submit_transfer() if the OS handles timeout */
342 USBI_TRANSFER_OS_HANDLES_TIMEOUT = 1 << 1,
344 /* Cancellation was requested via libusb_cancel_transfer() */
345 USBI_TRANSFER_CANCELLING = 1 << 2,
347 /* Operation on the transfer failed because the device disappeared */
348 USBI_TRANSFER_DEVICE_DISAPPEARED = 1 << 3,
351 #define USBI_TRANSFER_TO_LIBUSB_TRANSFER(transfer) \
352 ((struct libusb_transfer *)(((unsigned char *)(transfer)) \
353 + sizeof(struct usbi_transfer)))
354 #define LIBUSB_TRANSFER_TO_USBI_TRANSFER(transfer) \
355 ((struct usbi_transfer *)(((unsigned char *)(transfer)) \
356 - sizeof(struct usbi_transfer)))
358 static inline void *usbi_transfer_get_os_priv(struct usbi_transfer *transfer)
360 return ((unsigned char *)transfer) + sizeof(struct usbi_transfer)
361 + sizeof(struct libusb_transfer)
362 + (transfer->num_iso_packets
363 * sizeof(struct libusb_iso_packet_descriptor));
368 /* All standard descriptors have these 2 fields in common */
369 struct usb_descriptor_header {
371 uint8_t bDescriptorType;
374 /* shared data and functions */
376 int usbi_io_init(struct libusb_context *ctx);
377 void usbi_io_exit(struct libusb_context *ctx);
379 struct libusb_device *usbi_alloc_device(struct libusb_context *ctx,
380 unsigned long session_id);
381 struct libusb_device *usbi_get_device_by_session_id(struct libusb_context *ctx,
382 unsigned long session_id);
383 int usbi_sanitize_device(struct libusb_device *dev);
384 void usbi_handle_disconnect(struct libusb_device_handle *handle);
386 int usbi_handle_transfer_completion(struct usbi_transfer *itransfer,
387 enum libusb_transfer_status status);
388 int usbi_handle_transfer_cancellation(struct usbi_transfer *transfer);
390 int usbi_parse_descriptor(unsigned char *source, const char *descriptor,
391 void *dest, int host_endian);
392 int usbi_get_config_index_by_value(struct libusb_device *dev,
393 uint8_t bConfigurationValue, int *idx);
398 /* must come first */
399 struct libusb_pollfd pollfd;
401 struct list_head list;
404 int usbi_add_pollfd(struct libusb_context *ctx, int fd, short events);
405 void usbi_remove_pollfd(struct libusb_context *ctx, int fd);
406 void usbi_fd_notification(struct libusb_context *ctx);
408 /* device discovery */
410 /* we traverse usbfs without knowing how many devices we are going to find.
411 * so we create this discovered_devs model which is similar to a linked-list
412 * which grows when required. it can be freed once discovery has completed,
413 * eliminating the need for a list node in the libusb_device structure
415 struct discovered_devs {
418 struct libusb_device *devices[0];
421 struct discovered_devs *discovered_devs_append(
422 struct discovered_devs *discdevs, struct libusb_device *dev);
426 /* This is the interface that OS backends need to implement.
427 * All fields are mandatory, except ones explicitly noted as optional. */
428 struct usbi_os_backend {
429 /* A human-readable name for your backend, e.g. "Linux usbfs" */
432 /* Perform initialization of your backend. You might use this function
433 * to determine specific capabilities of the system, allocate required
434 * data structures for later, etc.
436 * This function is called when a libusbx user initializes the library
439 * Return 0 on success, or a LIBUSB_ERROR code on failure.
441 int (*init)(struct libusb_context *ctx);
443 /* Deinitialization. Optional. This function should destroy anything
444 * that was set up by init.
446 * This function is called when the user deinitializes the library.
450 /* Enumerate all the USB devices on the system, returning them in a list
451 * of discovered devices.
453 * Your implementation should enumerate all devices on the system,
454 * regardless of whether they have been seen before or not.
456 * When you have found a device, compute a session ID for it. The session
457 * ID should uniquely represent that particular device for that particular
458 * connection session since boot (i.e. if you disconnect and reconnect a
459 * device immediately after, it should be assigned a different session ID).
460 * If your OS cannot provide a unique session ID as described above,
461 * presenting a session ID of (bus_number << 8 | device_address) should
462 * be sufficient. Bus numbers and device addresses wrap and get reused,
463 * but that is an unlikely case.
465 * After computing a session ID for a device, call
466 * usbi_get_device_by_session_id(). This function checks if libusbx already
467 * knows about the device, and if so, it provides you with a libusb_device
470 * If usbi_get_device_by_session_id() returns NULL, it is time to allocate
471 * a new device structure for the device. Call usbi_alloc_device() to
472 * obtain a new libusb_device structure with reference count 1. Populate
473 * the bus_number and device_address attributes of the new device, and
474 * perform any other internal backend initialization you need to do. At
475 * this point, you should be ready to provide device descriptors and so
476 * on through the get_*_descriptor functions. Finally, call
477 * usbi_sanitize_device() to perform some final sanity checks on the
478 * device. Assuming all of the above succeeded, we can now continue.
479 * If any of the above failed, remember to unreference the device that
480 * was returned by usbi_alloc_device().
482 * At this stage we have a populated libusb_device structure (either one
483 * that was found earlier, or one that we have just allocated and
484 * populated). This can now be added to the discovered devices list
485 * using discovered_devs_append(). Note that discovered_devs_append()
486 * may reallocate the list, returning a new location for it, and also
487 * note that reallocation can fail. Your backend should handle these
488 * error conditions appropriately.
490 * This function should not generate any bus I/O and should not block.
491 * If I/O is required (e.g. reading the active configuration value), it is
492 * OK to ignore these suggestions :)
494 * This function is executed when the user wishes to retrieve a list
495 * of USB devices connected to the system.
497 * Return 0 on success, or a LIBUSB_ERROR code on failure.
499 int (*get_device_list)(struct libusb_context *ctx,
500 struct discovered_devs **discdevs);
502 /* Open a device for I/O and other USB operations. The device handle
503 * is preallocated for you, you can retrieve the device in question
504 * through handle->dev.
506 * Your backend should allocate any internal resources required for I/O
507 * and other operations so that those operations can happen (hopefully)
508 * without hiccup. This is also a good place to inform libusbx that it
509 * should monitor certain file descriptors related to this device -
510 * see the usbi_add_pollfd() function.
512 * This function should not generate any bus I/O and should not block.
514 * This function is called when the user attempts to obtain a device
515 * handle for a device.
519 * - LIBUSB_ERROR_ACCESS if the user has insufficient permissions
520 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since
522 * - another LIBUSB_ERROR code on other failure
524 * Do not worry about freeing the handle on failed open, the upper layers
527 int (*open)(struct libusb_device_handle *handle);
529 /* Close a device such that the handle cannot be used again. Your backend
530 * should destroy any resources that were allocated in the open path.
531 * This may also be a good place to call usbi_remove_pollfd() to inform
532 * libusbx of any file descriptors associated with this device that should
533 * no longer be monitored.
535 * This function is called when the user closes a device handle.
537 void (*close)(struct libusb_device_handle *handle);
539 /* Retrieve the device descriptor from a device.
541 * The descriptor should be retrieved from memory, NOT via bus I/O to the
542 * device. This means that you may have to cache it in a private structure
543 * during get_device_list enumeration. Alternatively, you may be able
544 * to retrieve it from a kernel interface (some Linux setups can do this)
545 * still without generating bus I/O.
547 * This function is expected to write DEVICE_DESC_LENGTH (18) bytes into
548 * buffer, which is guaranteed to be big enough.
550 * This function is called when sanity-checking a device before adding
551 * it to the list of discovered devices, and also when the user requests
552 * to read the device descriptor.
554 * This function is expected to return the descriptor in bus-endian format
555 * (LE). If it returns the multi-byte values in host-endian format,
556 * set the host_endian output parameter to "1".
558 * Return 0 on success or a LIBUSB_ERROR code on failure.
560 int (*get_device_descriptor)(struct libusb_device *device,
561 unsigned char *buffer, int *host_endian);
563 /* Get the ACTIVE configuration descriptor for a device.
565 * The descriptor should be retrieved from memory, NOT via bus I/O to the
566 * device. This means that you may have to cache it in a private structure
567 * during get_device_list enumeration. You may also have to keep track
568 * of which configuration is active when the user changes it.
570 * This function is expected to write len bytes of data into buffer, which
571 * is guaranteed to be big enough. If you can only do a partial write,
572 * return an error code.
574 * This function is expected to return the descriptor in bus-endian format
575 * (LE). If it returns the multi-byte values in host-endian format,
576 * set the host_endian output parameter to "1".
580 * - LIBUSB_ERROR_NOT_FOUND if the device is in unconfigured state
581 * - another LIBUSB_ERROR code on other failure
583 int (*get_active_config_descriptor)(struct libusb_device *device,
584 unsigned char *buffer, size_t len, int *host_endian);
586 /* Get a specific configuration descriptor for a device.
588 * The descriptor should be retrieved from memory, NOT via bus I/O to the
589 * device. This means that you may have to cache it in a private structure
590 * during get_device_list enumeration.
592 * The requested descriptor is expressed as a zero-based index (i.e. 0
593 * indicates that we are requesting the first descriptor). The index does
594 * not (necessarily) equal the bConfigurationValue of the configuration
597 * This function is expected to write len bytes of data into buffer, which
598 * is guaranteed to be big enough. If you can only do a partial write,
599 * return an error code.
601 * This function is expected to return the descriptor in bus-endian format
602 * (LE). If it returns the multi-byte values in host-endian format,
603 * set the host_endian output parameter to "1".
605 * Return 0 on success or a LIBUSB_ERROR code on failure.
607 int (*get_config_descriptor)(struct libusb_device *device,
608 uint8_t config_index, unsigned char *buffer, size_t len,
611 /* Get the bConfigurationValue for the active configuration for a device.
612 * Optional. This should only be implemented if you can retrieve it from
613 * cache (don't generate I/O).
615 * If you cannot retrieve this from cache, either do not implement this
616 * function, or return LIBUSB_ERROR_NOT_SUPPORTED. This will cause
617 * libusbx to retrieve the information through a standard control transfer.
619 * This function must be non-blocking.
622 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
624 * - LIBUSB_ERROR_NOT_SUPPORTED if the value cannot be retrieved without
626 * - another LIBUSB_ERROR code on other failure.
628 int (*get_configuration)(struct libusb_device_handle *handle, int *config);
630 /* Set the active configuration for a device.
632 * A configuration value of -1 should put the device in unconfigured state.
634 * This function can block.
638 * - LIBUSB_ERROR_NOT_FOUND if the configuration does not exist
639 * - LIBUSB_ERROR_BUSY if interfaces are currently claimed (and hence
640 * configuration cannot be changed)
641 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
643 * - another LIBUSB_ERROR code on other failure.
645 int (*set_configuration)(struct libusb_device_handle *handle, int config);
647 /* Claim an interface. When claimed, the application can then perform
648 * I/O to an interface's endpoints.
650 * This function should not generate any bus I/O and should not block.
651 * Interface claiming is a logical operation that simply ensures that
652 * no other drivers/applications are using the interface, and after
653 * claiming, no other drivers/applicatiosn can use the interface because
658 * - LIBUSB_ERROR_NOT_FOUND if the interface does not exist
659 * - LIBUSB_ERROR_BUSY if the interface is in use by another driver/app
660 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
662 * - another LIBUSB_ERROR code on other failure
664 int (*claim_interface)(struct libusb_device_handle *handle, int interface_number);
666 /* Release a previously claimed interface.
668 * This function should also generate a SET_INTERFACE control request,
669 * resetting the alternate setting of that interface to 0. It's OK for
670 * this function to block as a result.
672 * You will only ever be asked to release an interface which was
673 * successfully claimed earlier.
677 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
679 * - another LIBUSB_ERROR code on other failure
681 int (*release_interface)(struct libusb_device_handle *handle, int interface_number);
683 /* Set the alternate setting for an interface.
685 * You will only ever be asked to set the alternate setting for an
686 * interface which was successfully claimed earlier.
688 * It's OK for this function to block.
692 * - LIBUSB_ERROR_NOT_FOUND if the alternate setting does not exist
693 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
695 * - another LIBUSB_ERROR code on other failure
697 int (*set_interface_altsetting)(struct libusb_device_handle *handle,
698 int interface_number, int altsetting);
700 /* Clear a halt/stall condition on an endpoint.
702 * It's OK for this function to block.
706 * - LIBUSB_ERROR_NOT_FOUND if the endpoint does not exist
707 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
709 * - another LIBUSB_ERROR code on other failure
711 int (*clear_halt)(struct libusb_device_handle *handle,
712 unsigned char endpoint);
714 /* Perform a USB port reset to reinitialize a device.
716 * If possible, the handle should still be usable after the reset
717 * completes, assuming that the device descriptors did not change during
718 * reset and all previous interface state can be restored.
720 * If something changes, or you cannot easily locate/verify the resetted
721 * device, return LIBUSB_ERROR_NOT_FOUND. This prompts the application
722 * to close the old handle and re-enumerate the device.
726 * - LIBUSB_ERROR_NOT_FOUND if re-enumeration is required, or if the device
727 * has been disconnected since it was opened
728 * - another LIBUSB_ERROR code on other failure
730 int (*reset_device)(struct libusb_device_handle *handle);
732 /* Determine if a kernel driver is active on an interface. Optional.
734 * The presence of a kernel driver on an interface indicates that any
735 * calls to claim_interface would fail with the LIBUSB_ERROR_BUSY code.
738 * - 0 if no driver is active
739 * - 1 if a driver is active
740 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
742 * - another LIBUSB_ERROR code on other failure
744 int (*kernel_driver_active)(struct libusb_device_handle *handle,
745 int interface_number);
747 /* Detach a kernel driver from an interface. Optional.
749 * After detaching a kernel driver, the interface should be available
754 * - LIBUSB_ERROR_NOT_FOUND if no kernel driver was active
755 * - LIBUSB_ERROR_INVALID_PARAM if the interface does not exist
756 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
758 * - another LIBUSB_ERROR code on other failure
760 int (*detach_kernel_driver)(struct libusb_device_handle *handle,
761 int interface_number);
763 /* Attach a kernel driver to an interface. Optional.
765 * Reattach a kernel driver to the device.
769 * - LIBUSB_ERROR_NOT_FOUND if no kernel driver was active
770 * - LIBUSB_ERROR_INVALID_PARAM if the interface does not exist
771 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
773 * - LIBUSB_ERROR_BUSY if a program or driver has claimed the interface,
774 * preventing reattachment
775 * - another LIBUSB_ERROR code on other failure
777 int (*attach_kernel_driver)(struct libusb_device_handle *handle,
778 int interface_number);
780 /* Destroy a device. Optional.
782 * This function is called when the last reference to a device is
783 * destroyed. It should free any resources allocated in the get_device_list
786 void (*destroy_device)(struct libusb_device *dev);
788 /* Submit a transfer. Your implementation should take the transfer,
789 * morph it into whatever form your platform requires, and submit it
792 * This function must not block.
796 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
797 * - another LIBUSB_ERROR code on other failure
799 int (*submit_transfer)(struct usbi_transfer *itransfer);
801 /* Cancel a previously submitted transfer.
803 * This function must not block. The transfer cancellation must complete
804 * later, resulting in a call to usbi_handle_transfer_cancellation()
805 * from the context of handle_events.
807 int (*cancel_transfer)(struct usbi_transfer *itransfer);
809 /* Clear a transfer as if it has completed or cancelled, but do not
810 * report any completion/cancellation to the library. You should free
811 * all private data from the transfer as if you were just about to report
812 * completion or cancellation.
814 * This function might seem a bit out of place. It is used when libusbx
815 * detects a disconnected device - it calls this function for all pending
816 * transfers before reporting completion (with the disconnect code) to
817 * the user. Maybe we can improve upon this internal interface in future.
819 void (*clear_transfer_priv)(struct usbi_transfer *itransfer);
821 /* Handle any pending events. This involves monitoring any active
822 * transfers and processing their completion or cancellation.
824 * The function is passed an array of pollfd structures (size nfds)
825 * as a result of the poll() system call. The num_ready parameter
826 * indicates the number of file descriptors that have reported events
827 * (i.e. the poll() return value). This should be enough information
828 * for you to determine which actions need to be taken on the currently
831 * For any cancelled transfers, call usbi_handle_transfer_cancellation().
832 * For completed transfers, call usbi_handle_transfer_completion().
833 * For control/bulk/interrupt transfers, populate the "transferred"
834 * element of the appropriate usbi_transfer structure before calling the
835 * above functions. For isochronous transfers, populate the status and
836 * transferred fields of the iso packet descriptors of the transfer.
838 * This function should also be able to detect disconnection of the
839 * device, reporting that situation with usbi_handle_disconnect().
841 * When processing an event related to a transfer, you probably want to
842 * take usbi_transfer.lock to prevent races. See the documentation for
843 * the usbi_transfer structure.
845 * Return 0 on success, or a LIBUSB_ERROR code on failure.
847 int (*handle_events)(struct libusb_context *ctx,
848 struct pollfd *fds, POLL_NFDS_TYPE nfds, int num_ready);
850 /* Get time from specified clock. At least two clocks must be implemented
851 by the backend: USBI_CLOCK_REALTIME, and USBI_CLOCK_MONOTONIC.
853 Description of clocks:
854 USBI_CLOCK_REALTIME : clock returns time since system epoch.
855 USBI_CLOCK_MONOTONIC: clock returns time since unspecified start
858 int (*clock_gettime)(int clkid, struct timespec *tp);
860 #ifdef USBI_TIMERFD_AVAILABLE
861 /* clock ID of the clock that should be used for timerfd */
862 clockid_t (*get_timerfd_clockid)(void);
865 /* Number of bytes to reserve for per-device private backend data.
866 * This private data area is accessible through the "os_priv" field of
867 * struct libusb_device. */
868 size_t device_priv_size;
870 /* Number of bytes to reserve for per-handle private backend data.
871 * This private data area is accessible through the "os_priv" field of
872 * struct libusb_device. */
873 size_t device_handle_priv_size;
875 /* Number of bytes to reserve for per-transfer private backend data.
876 * This private data area is accessible by calling
877 * usbi_transfer_get_os_priv() on the appropriate usbi_transfer instance.
879 size_t transfer_priv_size;
881 /* Mumber of additional bytes for os_priv for each iso packet.
882 * Can your backend use this? */
883 /* FIXME: linux can't use this any more. if other OS's cannot either,
884 * then remove this */
885 size_t add_iso_packet_size;
888 extern const struct usbi_os_backend * const usbi_backend;
890 extern const struct usbi_os_backend linux_usbfs_backend;
891 extern const struct usbi_os_backend darwin_backend;
892 extern const struct usbi_os_backend openbsd_backend;
893 extern const struct usbi_os_backend windows_backend;