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
35 /* Inside the libusb code, mark all public functions as follows:
36 * return_type API_EXPORTED function_name(params) { ... }
37 * But if the function returns a pointer, mark it as follows:
38 * DEFAULT_VISIBILITY return_type * LIBUSB_CALL function_name(params) { ... }
39 * In the libusb public header, mark all declarations as:
40 * return_type LIBUSB_CALL function_name(params);
42 #define API_EXPORTED LIBUSB_CALL DEFAULT_VISIBILITY
44 #define DEVICE_DESC_LENGTH 18
46 #define USB_MAXENDPOINTS 32
47 #define USB_MAXINTERFACES 32
48 #define USB_MAXCONFIG 8
51 struct list_head *prev, *next;
54 /* Get an entry from the list
55 * ptr - the address of this list_head element in "type"
56 * type - the data type that contains "member"
57 * member - the list_head element in "type"
59 #define list_entry(ptr, type, member) \
60 ((type *)((uintptr_t)(ptr) - (uintptr_t)(&((type *)0L)->member)))
62 /* Get each entry from a list
63 * pos - A structure pointer has a "member" element
65 * member - the list_head element in "pos"
66 * type - the type of the first parameter
68 #define list_for_each_entry(pos, head, member, type) \
69 for (pos = list_entry((head)->next, type, member); \
70 &pos->member != (head); \
71 pos = list_entry(pos->member.next, type, member))
73 #define list_for_each_entry_safe(pos, n, head, member, type) \
74 for (pos = list_entry((head)->next, type, member), \
75 n = list_entry(pos->member.next, type, member); \
76 &pos->member != (head); \
77 pos = n, n = list_entry(n->member.next, type, member))
79 #define list_empty(entry) ((entry)->next == (entry))
81 static inline void list_init(struct list_head *entry)
83 entry->prev = entry->next = entry;
86 static inline void list_add(struct list_head *entry, struct list_head *head)
88 entry->next = head->next;
91 head->next->prev = entry;
95 static inline void list_add_tail(struct list_head *entry,
96 struct list_head *head)
99 entry->prev = head->prev;
101 head->prev->next = entry;
105 static inline void list_del(struct list_head *entry)
107 entry->next->prev = entry->prev;
108 entry->prev->next = entry->next;
111 #define container_of(ptr, type, member) ({ \
112 const typeof( ((type *)0)->member ) *__mptr = (ptr); \
113 (type *)( (char *)__mptr - offsetof(type,member) );})
115 #define MIN(a, b) ((a) < (b) ? (a) : (b))
116 #define MAX(a, b) ((a) > (b) ? (a) : (b))
118 #define TIMESPEC_IS_SET(ts) ((ts)->tv_sec != 0 || (ts)->tv_nsec != 0)
120 enum usbi_log_level {
127 void usbi_log(struct libusb_context *ctx, enum usbi_log_level level,
128 const char *function, const char *format, ...);
130 #if !defined(_MSC_VER) || _MSC_VER > 1200
132 #ifdef ENABLE_LOGGING
133 #define _usbi_log(ctx, level, ...) usbi_log(ctx, level, __FUNCTION__, __VA_ARGS__)
135 #define _usbi_log(ctx, level, ...) do {} while(0)
138 #ifdef ENABLE_DEBUG_LOGGING
139 #define usbi_dbg(...) _usbi_log(NULL, LOG_LEVEL_DEBUG, __VA_ARGS__)
141 #define usbi_dbg(...) do {} while(0)
144 #define usbi_info(ctx, ...) _usbi_log(ctx, LOG_LEVEL_INFO, __VA_ARGS__)
145 #define usbi_warn(ctx, ...) _usbi_log(ctx, LOG_LEVEL_WARNING, __VA_ARGS__)
146 #define usbi_err(ctx, ...) _usbi_log(ctx, LOG_LEVEL_ERROR, __VA_ARGS__)
148 #else /* !defined(_MSC_VER) || _MSC_VER > 1200 */
150 void usbi_log_v(struct libusb_context *ctx, enum usbi_log_level level,
151 const char *function, const char *format, va_list args);
153 #ifdef ENABLE_LOGGING
154 #define LOG_BODY(ctxt, level) \
157 va_start (args, format); \
158 usbi_log_v(ctxt, level, "", format, args); \
162 #define LOG_BODY(ctxt, level) { }
165 static inline void usbi_info(struct libusb_context *ctx, const char *format,
167 LOG_BODY(ctx,LOG_LEVEL_INFO)
168 static inline void usbi_warn(struct libusb_context *ctx, const char *format,
170 LOG_BODY(ctx,LOG_LEVEL_WARNING)
171 static inline void usbi_err( struct libusb_context *ctx, const char *format,
173 LOG_BODY(ctx,LOG_LEVEL_ERROR)
175 static inline void usbi_dbg(const char *format, ...)
176 #ifdef ENABLE_DEBUG_LOGGING
177 LOG_BODY(NULL,LOG_LEVEL_DEBUG)
182 #endif /* !defined(_MSC_VER) || _MSC_VER > 1200 */
184 #define USBI_GET_CONTEXT(ctx) if (!(ctx)) (ctx) = usbi_default_context
185 #define DEVICE_CTX(dev) ((dev)->ctx)
186 #define HANDLE_CTX(handle) (DEVICE_CTX((handle)->dev))
187 #define TRANSFER_CTX(transfer) (HANDLE_CTX((transfer)->dev_handle))
188 #define ITRANSFER_CTX(transfer) \
189 (TRANSFER_CTX(__USBI_TRANSFER_TO_LIBUSB_TRANSFER(transfer)))
191 /* Internal abstractions for thread synchronization and poll */
192 #if defined(THREADS_POSIX)
193 #include <os/threads_posix.h>
194 #elif defined(OS_WINDOWS)
195 #include <os/threads_windows.h>
198 #if defined(OS_LINUX) || defined(OS_DARWIN)
200 #include <os/poll_posix.h>
201 #elif defined(OS_WINDOWS)
202 #include <os/poll_windows.h>
205 extern struct libusb_context *usbi_default_context;
207 struct libusb_context {
211 /* internal control pipe, used for interrupting event handling when
212 * something needs to modify poll fds. */
215 struct list_head usb_devs;
216 usbi_mutex_t usb_devs_lock;
218 /* A list of open handles. Backends are free to traverse this if required.
220 struct list_head open_devs;
221 usbi_mutex_t open_devs_lock;
223 /* this is a list of in-flight transfer handles, sorted by timeout
224 * expiration. URBs to timeout the soonest are placed at the beginning of
225 * the list, URBs that will time out later are placed after, and urbs with
226 * infinite timeout are always placed at the very end. */
227 struct list_head flying_transfers;
228 usbi_mutex_t flying_transfers_lock;
230 /* list of poll fds */
231 struct list_head pollfds;
232 usbi_mutex_t pollfds_lock;
234 /* a counter that is set when we want to interrupt event handling, in order
235 * to modify the poll fd set. and a lock to protect it. */
236 unsigned int pollfd_modify;
237 usbi_mutex_t pollfd_modify_lock;
239 /* user callbacks for pollfd changes */
240 libusb_pollfd_added_cb fd_added_cb;
241 libusb_pollfd_removed_cb fd_removed_cb;
242 void *fd_cb_user_data;
244 /* ensures that only one thread is handling events at any one time */
245 usbi_mutex_t events_lock;
247 /* used to see if there is an active thread doing event handling */
248 int event_handler_active;
250 /* used to wait for event completion in threads other than the one that is
252 usbi_mutex_t event_waiters_lock;
253 usbi_cond_t event_waiters_cond;
255 #ifdef USBI_TIMERFD_AVAILABLE
256 /* used for timeout handling, if supported by OS.
257 * this timerfd is maintained to trigger on the next pending timeout */
262 #ifdef USBI_TIMERFD_AVAILABLE
263 #define usbi_using_timerfd(ctx) ((ctx)->timerfd >= 0)
265 #define usbi_using_timerfd(ctx) (0)
268 struct libusb_device {
269 /* lock protects refcnt, everything else is finalized at initialization
274 struct libusb_context *ctx;
277 uint8_t device_address;
278 uint8_t num_configurations;
279 enum libusb_speed speed;
281 struct list_head list;
282 unsigned long session_data;
283 unsigned char os_priv[0];
286 struct libusb_device_handle {
287 /* lock protects claimed_interfaces */
289 unsigned long claimed_interfaces;
291 struct list_head list;
292 struct libusb_device *dev;
293 unsigned char os_priv[0];
297 USBI_CLOCK_MONOTONIC,
301 /* in-memory transfer layout:
303 * 1. struct usbi_transfer
304 * 2. struct libusb_transfer (which includes iso packets) [variable size]
305 * 3. os private data [variable size]
307 * from a libusb_transfer, you can get the usbi_transfer by rewinding the
308 * appropriate number of bytes.
309 * the usbi_transfer includes the number of allocated packets, so you can
310 * determine the size of the transfer and hence the start and length of the
314 struct usbi_transfer {
316 struct list_head list;
317 struct timeval timeout;
321 /* this lock is held during libusb_submit_transfer() and
322 * libusb_cancel_transfer() (allowing the OS backend to prevent duplicate
323 * cancellation, submission-during-cancellation, etc). the OS backend
324 * should also take this lock in the handle_events path, to prevent the user
325 * cancelling the transfer from another thread while you are processing
326 * its completion (presumably there would be races within your OS backend
327 * if this were possible). */
331 enum usbi_transfer_flags {
332 /* The transfer has timed out */
333 USBI_TRANSFER_TIMED_OUT = 1 << 0,
335 /* Set by backend submit_transfer() if the OS handles timeout */
336 USBI_TRANSFER_OS_HANDLES_TIMEOUT = 1 << 1,
338 /* Cancellation was requested via libusb_cancel_transfer() */
339 USBI_TRANSFER_CANCELLING = 1 << 2,
341 /* Operation on the transfer failed because the device disappeared */
342 USBI_TRANSFER_DEVICE_DISAPPEARED = 1 << 3,
345 #define __USBI_TRANSFER_TO_LIBUSB_TRANSFER(transfer) \
346 ((struct libusb_transfer *)(((unsigned char *)(transfer)) \
347 + sizeof(struct usbi_transfer)))
348 #define __LIBUSB_TRANSFER_TO_USBI_TRANSFER(transfer) \
349 ((struct usbi_transfer *)(((unsigned char *)(transfer)) \
350 - sizeof(struct usbi_transfer)))
352 static inline void *usbi_transfer_get_os_priv(struct usbi_transfer *transfer)
354 return ((unsigned char *)transfer) + sizeof(struct usbi_transfer)
355 + sizeof(struct libusb_transfer)
356 + (transfer->num_iso_packets
357 * sizeof(struct libusb_iso_packet_descriptor));
362 /* All standard descriptors have these 2 fields in common */
363 struct usb_descriptor_header {
365 uint8_t bDescriptorType;
368 /* shared data and functions */
370 int usbi_io_init(struct libusb_context *ctx);
371 void usbi_io_exit(struct libusb_context *ctx);
373 struct libusb_device *usbi_alloc_device(struct libusb_context *ctx,
374 unsigned long session_id);
375 struct libusb_device *usbi_get_device_by_session_id(struct libusb_context *ctx,
376 unsigned long session_id);
377 int usbi_sanitize_device(struct libusb_device *dev);
378 void usbi_handle_disconnect(struct libusb_device_handle *handle);
380 int usbi_handle_transfer_completion(struct usbi_transfer *itransfer,
381 enum libusb_transfer_status status);
382 int usbi_handle_transfer_cancellation(struct usbi_transfer *transfer);
384 int usbi_parse_descriptor(unsigned char *source, const char *descriptor,
385 void *dest, int host_endian);
386 int usbi_get_config_index_by_value(struct libusb_device *dev,
387 uint8_t bConfigurationValue, int *idx);
392 /* must come first */
393 struct libusb_pollfd pollfd;
395 struct list_head list;
398 int usbi_add_pollfd(struct libusb_context *ctx, int fd, short events);
399 void usbi_remove_pollfd(struct libusb_context *ctx, int fd);
400 void usbi_fd_notification(struct libusb_context *ctx);
402 /* device discovery */
404 /* we traverse usbfs without knowing how many devices we are going to find.
405 * so we create this discovered_devs model which is similar to a linked-list
406 * which grows when required. it can be freed once discovery has completed,
407 * eliminating the need for a list node in the libusb_device structure
409 struct discovered_devs {
412 struct libusb_device *devices[0];
415 struct discovered_devs *discovered_devs_append(
416 struct discovered_devs *discdevs, struct libusb_device *dev);
420 /* This is the interface that OS backends need to implement.
421 * All fields are mandatory, except ones explicitly noted as optional. */
422 struct usbi_os_backend {
423 /* A human-readable name for your backend, e.g. "Linux usbfs" */
426 /* Perform initialization of your backend. You might use this function
427 * to determine specific capabilities of the system, allocate required
428 * data structures for later, etc.
430 * This function is called when a libusb user initializes the library
433 * Return 0 on success, or a LIBUSB_ERROR code on failure.
435 int (*init)(struct libusb_context *ctx);
437 /* Deinitialization. Optional. This function should destroy anything
438 * that was set up by init.
440 * This function is called when the user deinitializes the library.
444 /* Enumerate all the USB devices on the system, returning them in a list
445 * of discovered devices.
447 * Your implementation should enumerate all devices on the system,
448 * regardless of whether they have been seen before or not.
450 * When you have found a device, compute a session ID for it. The session
451 * ID should uniquely represent that particular device for that particular
452 * connection session since boot (i.e. if you disconnect and reconnect a
453 * device immediately after, it should be assigned a different session ID).
454 * If your OS cannot provide a unique session ID as described above,
455 * presenting a session ID of (bus_number << 8 | device_address) should
456 * be sufficient. Bus numbers and device addresses wrap and get reused,
457 * but that is an unlikely case.
459 * After computing a session ID for a device, call
460 * usbi_get_device_by_session_id(). This function checks if libusb already
461 * knows about the device, and if so, it provides you with a libusb_device
464 * If usbi_get_device_by_session_id() returns NULL, it is time to allocate
465 * a new device structure for the device. Call usbi_alloc_device() to
466 * obtain a new libusb_device structure with reference count 1. Populate
467 * the bus_number and device_address attributes of the new device, and
468 * perform any other internal backend initialization you need to do. At
469 * this point, you should be ready to provide device descriptors and so
470 * on through the get_*_descriptor functions. Finally, call
471 * usbi_sanitize_device() to perform some final sanity checks on the
472 * device. Assuming all of the above succeeded, we can now continue.
473 * If any of the above failed, remember to unreference the device that
474 * was returned by usbi_alloc_device().
476 * At this stage we have a populated libusb_device structure (either one
477 * that was found earlier, or one that we have just allocated and
478 * populated). This can now be added to the discovered devices list
479 * using discovered_devs_append(). Note that discovered_devs_append()
480 * may reallocate the list, returning a new location for it, and also
481 * note that reallocation can fail. Your backend should handle these
482 * error conditions appropriately.
484 * This function should not generate any bus I/O and should not block.
485 * If I/O is required (e.g. reading the active configuration value), it is
486 * OK to ignore these suggestions :)
488 * This function is executed when the user wishes to retrieve a list
489 * of USB devices connected to the system.
491 * Return 0 on success, or a LIBUSB_ERROR code on failure.
493 int (*get_device_list)(struct libusb_context *ctx,
494 struct discovered_devs **discdevs);
496 /* Open a device for I/O and other USB operations. The device handle
497 * is preallocated for you, you can retrieve the device in question
498 * through handle->dev.
500 * Your backend should allocate any internal resources required for I/O
501 * and other operations so that those operations can happen (hopefully)
502 * without hiccup. This is also a good place to inform libusb that it
503 * should monitor certain file descriptors related to this device -
504 * see the usbi_add_pollfd() function.
506 * This function should not generate any bus I/O and should not block.
508 * This function is called when the user attempts to obtain a device
509 * handle for a device.
513 * - LIBUSB_ERROR_ACCESS if the user has insufficient permissions
514 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since
516 * - another LIBUSB_ERROR code on other failure
518 * Do not worry about freeing the handle on failed open, the upper layers
521 int (*open)(struct libusb_device_handle *handle);
523 /* Close a device such that the handle cannot be used again. Your backend
524 * should destroy any resources that were allocated in the open path.
525 * This may also be a good place to call usbi_remove_pollfd() to inform
526 * libusb of any file descriptors associated with this device that should
527 * no longer be monitored.
529 * This function is called when the user closes a device handle.
531 void (*close)(struct libusb_device_handle *handle);
533 /* Retrieve the device descriptor from a device.
535 * The descriptor should be retrieved from memory, NOT via bus I/O to the
536 * device. This means that you may have to cache it in a private structure
537 * during get_device_list enumeration. Alternatively, you may be able
538 * to retrieve it from a kernel interface (some Linux setups can do this)
539 * still without generating bus I/O.
541 * This function is expected to write DEVICE_DESC_LENGTH (18) bytes into
542 * buffer, which is guaranteed to be big enough.
544 * This function is called when sanity-checking a device before adding
545 * it to the list of discovered devices, and also when the user requests
546 * to read the device descriptor.
548 * This function is expected to return the descriptor in bus-endian format
549 * (LE). If it returns the multi-byte values in host-endian format,
550 * set the host_endian output parameter to "1".
552 * Return 0 on success or a LIBUSB_ERROR code on failure.
554 int (*get_device_descriptor)(struct libusb_device *device,
555 unsigned char *buffer, int *host_endian);
557 /* Get the ACTIVE configuration descriptor for a device.
559 * The descriptor should be retrieved from memory, NOT via bus I/O to the
560 * device. This means that you may have to cache it in a private structure
561 * during get_device_list enumeration. You may also have to keep track
562 * of which configuration is active when the user changes it.
564 * This function is expected to write len bytes of data into buffer, which
565 * is guaranteed to be big enough. If you can only do a partial write,
566 * return an error code.
568 * This function is expected to return the descriptor in bus-endian format
569 * (LE). If it returns the multi-byte values in host-endian format,
570 * set the host_endian output parameter to "1".
574 * - LIBUSB_ERROR_NOT_FOUND if the device is in unconfigured state
575 * - another LIBUSB_ERROR code on other failure
577 int (*get_active_config_descriptor)(struct libusb_device *device,
578 unsigned char *buffer, size_t len, int *host_endian);
580 /* Get a specific configuration descriptor for a device.
582 * The descriptor should be retrieved from memory, NOT via bus I/O to the
583 * device. This means that you may have to cache it in a private structure
584 * during get_device_list enumeration.
586 * The requested descriptor is expressed as a zero-based index (i.e. 0
587 * indicates that we are requesting the first descriptor). The index does
588 * not (necessarily) equal the bConfigurationValue of the configuration
591 * This function is expected to write len bytes of data into buffer, which
592 * is guaranteed to be big enough. If you can only do a partial write,
593 * return an error code.
595 * This function is expected to return the descriptor in bus-endian format
596 * (LE). If it returns the multi-byte values in host-endian format,
597 * set the host_endian output parameter to "1".
599 * Return 0 on success or a LIBUSB_ERROR code on failure.
601 int (*get_config_descriptor)(struct libusb_device *device,
602 uint8_t config_index, unsigned char *buffer, size_t len,
605 /* Get the bConfigurationValue for the active configuration for a device.
606 * Optional. This should only be implemented if you can retrieve it from
607 * cache (don't generate I/O).
609 * If you cannot retrieve this from cache, either do not implement this
610 * function, or return LIBUSB_ERROR_NOT_SUPPORTED. This will cause
611 * libusb to retrieve the information through a standard control transfer.
613 * This function must be non-blocking.
616 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
618 * - LIBUSB_ERROR_NOT_SUPPORTED if the value cannot be retrieved without
620 * - another LIBUSB_ERROR code on other failure.
622 int (*get_configuration)(struct libusb_device_handle *handle, int *config);
624 /* Set the active configuration for a device.
626 * A configuration value of -1 should put the device in unconfigured state.
628 * This function can block.
632 * - LIBUSB_ERROR_NOT_FOUND if the configuration does not exist
633 * - LIBUSB_ERROR_BUSY if interfaces are currently claimed (and hence
634 * configuration cannot be changed)
635 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
637 * - another LIBUSB_ERROR code on other failure.
639 int (*set_configuration)(struct libusb_device_handle *handle, int config);
641 /* Claim an interface. When claimed, the application can then perform
642 * I/O to an interface's endpoints.
644 * This function should not generate any bus I/O and should not block.
645 * Interface claiming is a logical operation that simply ensures that
646 * no other drivers/applications are using the interface, and after
647 * claiming, no other drivers/applicatiosn can use the interface because
652 * - LIBUSB_ERROR_NOT_FOUND if the interface does not exist
653 * - LIBUSB_ERROR_BUSY if the interface is in use by another driver/app
654 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
656 * - another LIBUSB_ERROR code on other failure
658 int (*claim_interface)(struct libusb_device_handle *handle, int interface_number);
660 /* Release a previously claimed interface.
662 * This function should also generate a SET_INTERFACE control request,
663 * resetting the alternate setting of that interface to 0. It's OK for
664 * this function to block as a result.
666 * You will only ever be asked to release an interface which was
667 * successfully claimed earlier.
671 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
673 * - another LIBUSB_ERROR code on other failure
675 int (*release_interface)(struct libusb_device_handle *handle, int interface_number);
677 /* Set the alternate setting for an interface.
679 * You will only ever be asked to set the alternate setting for an
680 * interface which was successfully claimed earlier.
682 * It's OK for this function to block.
686 * - LIBUSB_ERROR_NOT_FOUND if the alternate setting does not exist
687 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
689 * - another LIBUSB_ERROR code on other failure
691 int (*set_interface_altsetting)(struct libusb_device_handle *handle,
692 int interface_number, int altsetting);
694 /* Clear a halt/stall condition on an endpoint.
696 * It's OK for this function to block.
700 * - LIBUSB_ERROR_NOT_FOUND if the endpoint does not exist
701 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
703 * - another LIBUSB_ERROR code on other failure
705 int (*clear_halt)(struct libusb_device_handle *handle,
706 unsigned char endpoint);
708 /* Perform a USB port reset to reinitialize a device.
710 * If possible, the handle should still be usable after the reset
711 * completes, assuming that the device descriptors did not change during
712 * reset and all previous interface state can be restored.
714 * If something changes, or you cannot easily locate/verify the resetted
715 * device, return LIBUSB_ERROR_NOT_FOUND. This prompts the application
716 * to close the old handle and re-enumerate the device.
720 * - LIBUSB_ERROR_NOT_FOUND if re-enumeration is required, or if the device
721 * has been disconnected since it was opened
722 * - another LIBUSB_ERROR code on other failure
724 int (*reset_device)(struct libusb_device_handle *handle);
726 /* Determine if a kernel driver is active on an interface. Optional.
728 * The presence of a kernel driver on an interface indicates that any
729 * calls to claim_interface would fail with the LIBUSB_ERROR_BUSY code.
732 * - 0 if no driver is active
733 * - 1 if a driver is active
734 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
736 * - another LIBUSB_ERROR code on other failure
738 int (*kernel_driver_active)(struct libusb_device_handle *handle,
739 int interface_number);
741 /* Detach a kernel driver from an interface. Optional.
743 * After detaching a kernel driver, the interface should be available
748 * - LIBUSB_ERROR_NOT_FOUND if no kernel driver was active
749 * - LIBUSB_ERROR_INVALID_PARAM if the interface does not exist
750 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
752 * - another LIBUSB_ERROR code on other failure
754 int (*detach_kernel_driver)(struct libusb_device_handle *handle,
755 int interface_number);
757 /* Attach a kernel driver to an interface. Optional.
759 * Reattach a kernel driver to the device.
763 * - LIBUSB_ERROR_NOT_FOUND if no kernel driver was active
764 * - LIBUSB_ERROR_INVALID_PARAM if the interface does not exist
765 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
767 * - LIBUSB_ERROR_BUSY if a program or driver has claimed the interface,
768 * preventing reattachment
769 * - another LIBUSB_ERROR code on other failure
771 int (*attach_kernel_driver)(struct libusb_device_handle *handle,
772 int interface_number);
774 /* Destroy a device. Optional.
776 * This function is called when the last reference to a device is
777 * destroyed. It should free any resources allocated in the get_device_list
780 void (*destroy_device)(struct libusb_device *dev);
782 /* Submit a transfer. Your implementation should take the transfer,
783 * morph it into whatever form your platform requires, and submit it
786 * This function must not block.
790 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
791 * - another LIBUSB_ERROR code on other failure
793 int (*submit_transfer)(struct usbi_transfer *itransfer);
795 /* Cancel a previously submitted transfer.
797 * This function must not block. The transfer cancellation must complete
798 * later, resulting in a call to usbi_handle_transfer_cancellation()
799 * from the context of handle_events.
801 int (*cancel_transfer)(struct usbi_transfer *itransfer);
803 /* Clear a transfer as if it has completed or cancelled, but do not
804 * report any completion/cancellation to the library. You should free
805 * all private data from the transfer as if you were just about to report
806 * completion or cancellation.
808 * This function might seem a bit out of place. It is used when libusb
809 * detects a disconnected device - it calls this function for all pending
810 * transfers before reporting completion (with the disconnect code) to
811 * the user. Maybe we can improve upon this internal interface in future.
813 void (*clear_transfer_priv)(struct usbi_transfer *itransfer);
815 /* Handle any pending events. This involves monitoring any active
816 * transfers and processing their completion or cancellation.
818 * The function is passed an array of pollfd structures (size nfds)
819 * as a result of the poll() system call. The num_ready parameter
820 * indicates the number of file descriptors that have reported events
821 * (i.e. the poll() return value). This should be enough information
822 * for you to determine which actions need to be taken on the currently
825 * For any cancelled transfers, call usbi_handle_transfer_cancellation().
826 * For completed transfers, call usbi_handle_transfer_completion().
827 * For control/bulk/interrupt transfers, populate the "transferred"
828 * element of the appropriate usbi_transfer structure before calling the
829 * above functions. For isochronous transfers, populate the status and
830 * transferred fields of the iso packet descriptors of the transfer.
832 * This function should also be able to detect disconnection of the
833 * device, reporting that situation with usbi_handle_disconnect().
835 * When processing an event related to a transfer, you probably want to
836 * take usbi_transfer.lock to prevent races. See the documentation for
837 * the usbi_transfer structure.
839 * Return 0 on success, or a LIBUSB_ERROR code on failure.
841 int (*handle_events)(struct libusb_context *ctx,
842 struct pollfd *fds, POLL_NFDS_TYPE nfds, int num_ready);
844 /* Get time from specified clock. At least two clocks must be implemented
845 by the backend: USBI_CLOCK_REALTIME, and USBI_CLOCK_MONOTONIC.
847 Description of clocks:
848 USBI_CLOCK_REALTIME : clock returns time since system epoch.
849 USBI_CLOCK_MONOTONIC: clock returns time since unspecified start
852 int (*clock_gettime)(int clkid, struct timespec *tp);
854 #ifdef USBI_TIMERFD_AVAILABLE
855 /* clock ID of the clock that should be used for timerfd */
856 clockid_t (*get_timerfd_clockid)(void);
859 /* Number of bytes to reserve for per-device private backend data.
860 * This private data area is accessible through the "os_priv" field of
861 * struct libusb_device. */
862 size_t device_priv_size;
864 /* Number of bytes to reserve for per-handle private backend data.
865 * This private data area is accessible through the "os_priv" field of
866 * struct libusb_device. */
867 size_t device_handle_priv_size;
869 /* Number of bytes to reserve for per-transfer private backend data.
870 * This private data area is accessible by calling
871 * usbi_transfer_get_os_priv() on the appropriate usbi_transfer instance.
873 size_t transfer_priv_size;
875 /* Mumber of additional bytes for os_priv for each iso packet.
876 * Can your backend use this? */
877 /* FIXME: linux can't use this any more. if other OS's cannot either,
878 * then remove this */
879 size_t add_iso_packet_size;
882 extern const struct usbi_os_backend * const usbi_backend;
884 extern const struct usbi_os_backend linux_usbfs_backend;
885 extern const struct usbi_os_backend darwin_backend;
886 extern const struct usbi_os_backend windows_backend;