2 * Internal header for libusb
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
42 /* Attribute to ensure that a structure member is aligned to a natural
43 * pointer alignment. Used for os_priv member. */
46 #define PTR_ALIGNED __declspec(align(8))
48 #define PTR_ALIGNED __declspec(align(4))
50 #elif defined(__GNUC__)
51 #define PTR_ALIGNED __attribute__((aligned(sizeof(void *))))
56 /* Inside the libusb code, mark all public functions as follows:
57 * return_type API_EXPORTED function_name(params) { ... }
58 * But if the function returns a pointer, mark it as follows:
59 * DEFAULT_VISIBILITY return_type * LIBUSB_CALL function_name(params) { ... }
60 * In the libusb public header, mark all declarations as:
61 * return_type LIBUSB_CALL function_name(params);
63 #define API_EXPORTED LIBUSB_CALL DEFAULT_VISIBILITY
69 #define DEVICE_DESC_LENGTH 18
71 #define USB_MAXENDPOINTS 32
72 #define USB_MAXINTERFACES 32
73 #define USB_MAXCONFIG 8
75 /* Backend specific capabilities */
76 #define USBI_CAP_HAS_HID_ACCESS 0x00010000
77 #define USBI_CAP_SUPPORTS_DETACH_KERNEL_DRIVER 0x00020000
79 /* Maximum number of bytes in a log line */
80 #define USBI_MAX_LOG_LEN 1024
81 /* Terminator for log lines */
82 #define USBI_LOG_LINE_END "\n"
84 /* The following is used to silence warnings for unused variables */
85 #define UNUSED(var) do { (void)(var); } while(0)
87 #if !defined(ARRAYSIZE)
88 #define ARRAYSIZE(array) (sizeof(array) / sizeof(array[0]))
92 struct list_head *prev, *next;
95 /* Get an entry from the list
96 * ptr - the address of this list_head element in "type"
97 * type - the data type that contains "member"
98 * member - the list_head element in "type"
100 #define list_entry(ptr, type, member) \
101 ((type *)((uintptr_t)(ptr) - (uintptr_t)offsetof(type, member)))
103 #define list_first_entry(ptr, type, member) \
104 list_entry((ptr)->next, type, member)
106 /* Get each entry from a list
107 * pos - A structure pointer has a "member" element
109 * member - the list_head element in "pos"
110 * type - the type of the first parameter
112 #define list_for_each_entry(pos, head, member, type) \
113 for (pos = list_entry((head)->next, type, member); \
114 &pos->member != (head); \
115 pos = list_entry(pos->member.next, type, member))
117 #define list_for_each_entry_safe(pos, n, head, member, type) \
118 for (pos = list_entry((head)->next, type, member), \
119 n = list_entry(pos->member.next, type, member); \
120 &pos->member != (head); \
121 pos = n, n = list_entry(n->member.next, type, member))
123 #define list_empty(entry) ((entry)->next == (entry))
125 static inline void list_init(struct list_head *entry)
127 entry->prev = entry->next = entry;
130 static inline void list_add(struct list_head *entry, struct list_head *head)
132 entry->next = head->next;
135 head->next->prev = entry;
139 static inline void list_add_tail(struct list_head *entry,
140 struct list_head *head)
143 entry->prev = head->prev;
145 head->prev->next = entry;
149 static inline void list_del(struct list_head *entry)
151 entry->next->prev = entry->prev;
152 entry->prev->next = entry->next;
153 entry->next = entry->prev = NULL;
156 static inline void list_cut(struct list_head *list, struct list_head *head)
158 if (list_empty(head))
161 list->next = head->next;
162 list->next->prev = list;
163 list->prev = head->prev;
164 list->prev->next = list;
169 static inline void *usbi_reallocf(void *ptr, size_t size)
171 void *ret = realloc(ptr, size);
177 #define container_of(ptr, type, member) ({ \
178 const typeof( ((type *)0)->member ) *mptr = (ptr); \
179 (type *)( (char *)mptr - offsetof(type,member) );})
182 #define MIN(a, b) ((a) < (b) ? (a) : (b))
185 #define MAX(a, b) ((a) > (b) ? (a) : (b))
188 #define TIMESPEC_IS_SET(ts) ((ts)->tv_sec != 0 || (ts)->tv_nsec != 0)
190 #if defined(_WIN32) || defined(__CYGWIN__) || defined(_WIN32_WCE)
191 #define TIMEVAL_TV_SEC_TYPE long
193 #define TIMEVAL_TV_SEC_TYPE time_t
196 /* Some platforms don't have this define */
197 #ifndef TIMESPEC_TO_TIMEVAL
198 #define TIMESPEC_TO_TIMEVAL(tv, ts) \
200 (tv)->tv_sec = (TIMEVAL_TV_SEC_TYPE) (ts)->tv_sec; \
201 (tv)->tv_usec = (ts)->tv_nsec / 1000; \
205 void usbi_log(struct libusb_context *ctx, enum libusb_log_level level,
206 const char *function, const char *format, ...);
208 void usbi_log_v(struct libusb_context *ctx, enum libusb_log_level level,
209 const char *function, const char *format, va_list args);
211 #if !defined(_MSC_VER) || _MSC_VER >= 1400
213 #ifdef ENABLE_LOGGING
214 #define _usbi_log(ctx, level, ...) usbi_log(ctx, level, __FUNCTION__, __VA_ARGS__)
215 #define usbi_dbg(...) _usbi_log(NULL, LIBUSB_LOG_LEVEL_DEBUG, __VA_ARGS__)
217 #define _usbi_log(ctx, level, ...) do { (void)(ctx); } while(0)
218 #define usbi_dbg(...) do {} while(0)
221 #define usbi_info(ctx, ...) _usbi_log(ctx, LIBUSB_LOG_LEVEL_INFO, __VA_ARGS__)
222 #define usbi_warn(ctx, ...) _usbi_log(ctx, LIBUSB_LOG_LEVEL_WARNING, __VA_ARGS__)
223 #define usbi_err(ctx, ...) _usbi_log(ctx, LIBUSB_LOG_LEVEL_ERROR, __VA_ARGS__)
225 #else /* !defined(_MSC_VER) || _MSC_VER >= 1400 */
227 #ifdef ENABLE_LOGGING
228 #define LOG_BODY(ctxt, level) \
231 va_start(args, format); \
232 usbi_log_v(ctxt, level, "", format, args); \
236 #define LOG_BODY(ctxt, level) \
242 static inline void usbi_info(struct libusb_context *ctx, const char *format, ...)
243 LOG_BODY(ctx, LIBUSB_LOG_LEVEL_INFO)
244 static inline void usbi_warn(struct libusb_context *ctx, const char *format, ...)
245 LOG_BODY(ctx, LIBUSB_LOG_LEVEL_WARNING)
246 static inline void usbi_err(struct libusb_context *ctx, const char *format, ...)
247 LOG_BODY(ctx, LIBUSB_LOG_LEVEL_ERROR)
249 static inline void usbi_dbg(const char *format, ...)
250 LOG_BODY(NULL, LIBUSB_LOG_LEVEL_DEBUG)
252 #endif /* !defined(_MSC_VER) || _MSC_VER >= 1400 */
254 #define USBI_GET_CONTEXT(ctx) \
257 (ctx) = usbi_default_context; \
260 #define DEVICE_CTX(dev) ((dev)->ctx)
261 #define HANDLE_CTX(handle) (DEVICE_CTX((handle)->dev))
262 #define TRANSFER_CTX(transfer) (HANDLE_CTX((transfer)->dev_handle))
263 #define ITRANSFER_CTX(transfer) \
264 (TRANSFER_CTX(USBI_TRANSFER_TO_LIBUSB_TRANSFER(transfer)))
266 #define IS_EPIN(ep) (0 != ((ep) & LIBUSB_ENDPOINT_IN))
267 #define IS_EPOUT(ep) (!IS_EPIN(ep))
268 #define IS_XFERIN(xfer) (0 != ((xfer)->endpoint & LIBUSB_ENDPOINT_IN))
269 #define IS_XFEROUT(xfer) (!IS_XFERIN(xfer))
271 /* Internal abstraction for thread synchronization */
272 #if defined(THREADS_POSIX)
273 #include "os/threads_posix.h"
274 #elif defined(OS_WINDOWS) || defined(OS_WINCE)
275 #include "os/threads_windows.h"
278 extern struct libusb_context *usbi_default_context;
280 /* Forward declaration for use in context (fully defined inside poll abstraction) */
283 struct libusb_context {
287 /* internal event pipe, used for signalling occurrence of an internal event. */
290 struct list_head usb_devs;
291 usbi_mutex_t usb_devs_lock;
293 /* A list of open handles. Backends are free to traverse this if required.
295 struct list_head open_devs;
296 usbi_mutex_t open_devs_lock;
298 /* A list of registered hotplug callbacks */
299 struct list_head hotplug_cbs;
300 usbi_mutex_t hotplug_cbs_lock;
302 /* this is a list of in-flight transfer handles, sorted by timeout
303 * expiration. URBs to timeout the soonest are placed at the beginning of
304 * the list, URBs that will time out later are placed after, and urbs with
305 * infinite timeout are always placed at the very end. */
306 struct list_head flying_transfers;
307 /* Note paths taking both this and usbi_transfer->lock must always
308 * take this lock first */
309 usbi_mutex_t flying_transfers_lock;
311 /* user callbacks for pollfd changes */
312 libusb_pollfd_added_cb fd_added_cb;
313 libusb_pollfd_removed_cb fd_removed_cb;
314 void *fd_cb_user_data;
316 /* ensures that only one thread is handling events at any one time */
317 usbi_mutex_t events_lock;
319 /* used to see if there is an active thread doing event handling */
320 int event_handler_active;
322 /* A thread-local storage key to track which thread is performing event
324 usbi_tls_key_t event_handling_key;
326 /* used to wait for event completion in threads other than the one that is
328 usbi_mutex_t event_waiters_lock;
329 usbi_cond_t event_waiters_cond;
331 /* A lock to protect internal context event data. */
332 usbi_mutex_t event_data_lock;
334 /* A bitmask of flags that are set to indicate specific events that need to
335 * be handled. Protected by event_data_lock. */
336 unsigned int event_flags;
338 /* A counter that is set when we want to interrupt and prevent event handling,
339 * in order to safely close a device. Protected by event_data_lock. */
340 unsigned int device_close;
342 /* list and count of poll fds and an array of poll fd structures that is
343 * (re)allocated as necessary prior to polling. Protected by event_data_lock. */
344 struct list_head ipollfds;
345 struct pollfd *pollfds;
346 POLL_NFDS_TYPE pollfds_cnt;
348 /* A list of pending hotplug messages. Protected by event_data_lock. */
349 struct list_head hotplug_msgs;
351 /* A list of pending completed transfers. Protected by event_data_lock. */
352 struct list_head completed_transfers;
354 #ifdef USBI_TIMERFD_AVAILABLE
355 /* used for timeout handling, if supported by OS.
356 * this timerfd is maintained to trigger on the next pending timeout */
360 struct list_head list;
363 enum usbi_event_flags {
364 /* The list of pollfds has been modified */
365 USBI_EVENT_POLLFDS_MODIFIED = 1 << 0,
367 /* The user has interrupted the event handler */
368 USBI_EVENT_USER_INTERRUPT = 1 << 1,
371 /* Macros for managing event handling state */
372 #define usbi_handling_events(ctx) \
373 (usbi_tls_key_get((ctx)->event_handling_key) != NULL)
375 #define usbi_start_event_handling(ctx) \
376 usbi_tls_key_set((ctx)->event_handling_key, ctx)
378 #define usbi_end_event_handling(ctx) \
379 usbi_tls_key_set((ctx)->event_handling_key, NULL)
381 /* Update the following macro if new event sources are added */
382 #define usbi_pending_events(ctx) \
383 ((ctx)->event_flags || (ctx)->device_close \
384 || !list_empty(&(ctx)->hotplug_msgs) || !list_empty(&(ctx)->completed_transfers))
386 #ifdef USBI_TIMERFD_AVAILABLE
387 #define usbi_using_timerfd(ctx) ((ctx)->timerfd >= 0)
389 #define usbi_using_timerfd(ctx) (0)
392 struct libusb_device {
393 /* lock protects refcnt, everything else is finalized at initialization
398 struct libusb_context *ctx;
402 struct libusb_device* parent_dev;
403 uint8_t device_address;
404 uint8_t num_configurations;
405 enum libusb_speed speed;
407 struct list_head list;
408 unsigned long session_data;
410 struct libusb_device_descriptor device_descriptor;
413 PTR_ALIGNED unsigned char os_priv[ZERO_SIZED_ARRAY];
416 struct libusb_device_handle {
417 /* lock protects claimed_interfaces */
419 unsigned long claimed_interfaces;
421 struct list_head list;
422 struct libusb_device *dev;
423 int auto_detach_kernel_driver;
425 PTR_ALIGNED unsigned char os_priv[ZERO_SIZED_ARRAY];
429 USBI_CLOCK_MONOTONIC,
433 /* in-memory transfer layout:
435 * 1. struct usbi_transfer
436 * 2. struct libusb_transfer (which includes iso packets) [variable size]
437 * 3. os private data [variable size]
439 * from a libusb_transfer, you can get the usbi_transfer by rewinding the
440 * appropriate number of bytes.
441 * the usbi_transfer includes the number of allocated packets, so you can
442 * determine the size of the transfer and hence the start and length of the
446 struct usbi_transfer {
448 struct list_head list;
449 struct list_head completed_list;
450 struct timeval timeout;
453 uint8_t state_flags; /* Protected by usbi_transfer->lock */
454 uint8_t timeout_flags; /* Protected by the flying_stransfers_lock */
456 /* this lock is held during libusb_submit_transfer() and
457 * libusb_cancel_transfer() (allowing the OS backend to prevent duplicate
458 * cancellation, submission-during-cancellation, etc). the OS backend
459 * should also take this lock in the handle_events path, to prevent the user
460 * cancelling the transfer from another thread while you are processing
461 * its completion (presumably there would be races within your OS backend
462 * if this were possible).
463 * Note paths taking both this and the flying_transfers_lock must
464 * always take the flying_transfers_lock first */
468 enum usbi_transfer_state_flags {
469 /* Transfer successfully submitted by backend */
470 USBI_TRANSFER_IN_FLIGHT = 1 << 0,
472 /* Cancellation was requested via libusb_cancel_transfer() */
473 USBI_TRANSFER_CANCELLING = 1 << 1,
475 /* Operation on the transfer failed because the device disappeared */
476 USBI_TRANSFER_DEVICE_DISAPPEARED = 1 << 2,
479 enum usbi_transfer_timeout_flags {
480 /* Set by backend submit_transfer() if the OS handles timeout */
481 USBI_TRANSFER_OS_HANDLES_TIMEOUT = 1 << 0,
483 /* The transfer timeout has been handled */
484 USBI_TRANSFER_TIMEOUT_HANDLED = 1 << 1,
486 /* The transfer timeout was successfully processed */
487 USBI_TRANSFER_TIMED_OUT = 1 << 2,
490 #define USBI_TRANSFER_TO_LIBUSB_TRANSFER(transfer) \
491 ((struct libusb_transfer *)(((unsigned char *)(transfer)) \
492 + sizeof(struct usbi_transfer)))
493 #define LIBUSB_TRANSFER_TO_USBI_TRANSFER(transfer) \
494 ((struct usbi_transfer *)(((unsigned char *)(transfer)) \
495 - sizeof(struct usbi_transfer)))
497 static inline void *usbi_transfer_get_os_priv(struct usbi_transfer *transfer)
499 return ((unsigned char *)transfer) + sizeof(struct usbi_transfer)
500 + sizeof(struct libusb_transfer)
501 + (transfer->num_iso_packets
502 * sizeof(struct libusb_iso_packet_descriptor));
507 /* All standard descriptors have these 2 fields in common */
508 struct usb_descriptor_header {
510 uint8_t bDescriptorType;
513 /* shared data and functions */
515 int usbi_io_init(struct libusb_context *ctx);
516 void usbi_io_exit(struct libusb_context *ctx);
518 struct libusb_device *usbi_alloc_device(struct libusb_context *ctx,
519 unsigned long session_id);
520 struct libusb_device *usbi_get_device_by_session_id(struct libusb_context *ctx,
521 unsigned long session_id);
522 int usbi_sanitize_device(struct libusb_device *dev);
523 void usbi_handle_disconnect(struct libusb_device_handle *dev_handle);
525 int usbi_handle_transfer_completion(struct usbi_transfer *itransfer,
526 enum libusb_transfer_status status);
527 int usbi_handle_transfer_cancellation(struct usbi_transfer *transfer);
528 void usbi_signal_transfer_completion(struct usbi_transfer *transfer);
530 int usbi_parse_descriptor(const unsigned char *source, const char *descriptor,
531 void *dest, int host_endian);
532 int usbi_device_cache_descriptor(libusb_device *dev);
533 int usbi_get_config_index_by_value(struct libusb_device *dev,
534 uint8_t bConfigurationValue, int *idx);
536 void usbi_connect_device (struct libusb_device *dev);
537 void usbi_disconnect_device (struct libusb_device *dev);
539 int usbi_signal_event(struct libusb_context *ctx);
540 int usbi_clear_event(struct libusb_context *ctx);
542 /* Internal abstraction for poll (needs struct usbi_transfer on Windows) */
543 #if defined(OS_LINUX) || defined(OS_DARWIN) || defined(OS_OPENBSD) || defined(OS_NETBSD) ||\
544 defined(OS_HAIKU) || defined(OS_SUNOS)
546 #include "os/poll_posix.h"
547 #elif defined(OS_WINDOWS) || defined(OS_WINCE)
548 #include "os/poll_windows.h"
551 #if defined(_MSC_VER) && (_MSC_VER < 1900)
552 #define snprintf usbi_snprintf
553 #define vsnprintf usbi_vsnprintf
554 int usbi_snprintf(char *dst, size_t size, const char *format, ...);
555 int usbi_vsnprintf(char *dst, size_t size, const char *format, va_list ap);
556 #define LIBUSB_PRINTF_WIN32
560 /* must come first */
561 struct libusb_pollfd pollfd;
563 struct list_head list;
566 int usbi_add_pollfd(struct libusb_context *ctx, int fd, short events);
567 void usbi_remove_pollfd(struct libusb_context *ctx, int fd);
569 /* device discovery */
571 /* we traverse usbfs without knowing how many devices we are going to find.
572 * so we create this discovered_devs model which is similar to a linked-list
573 * which grows when required. it can be freed once discovery has completed,
574 * eliminating the need for a list node in the libusb_device structure
576 struct discovered_devs {
579 struct libusb_device *devices[ZERO_SIZED_ARRAY];
582 struct discovered_devs *discovered_devs_append(
583 struct discovered_devs *discdevs, struct libusb_device *dev);
587 /* This is the interface that OS backends need to implement.
588 * All fields are mandatory, except ones explicitly noted as optional. */
589 struct usbi_os_backend {
590 /* A human-readable name for your backend, e.g. "Linux usbfs" */
593 /* Binary mask for backend specific capabilities */
596 /* Perform initialization of your backend. You might use this function
597 * to determine specific capabilities of the system, allocate required
598 * data structures for later, etc.
600 * This function is called when a libusb user initializes the library
603 * Return 0 on success, or a LIBUSB_ERROR code on failure.
605 int (*init)(struct libusb_context *ctx);
607 /* Deinitialization. Optional. This function should destroy anything
608 * that was set up by init.
610 * This function is called when the user deinitializes the library.
614 /* Enumerate all the USB devices on the system, returning them in a list
615 * of discovered devices.
617 * Your implementation should enumerate all devices on the system,
618 * regardless of whether they have been seen before or not.
620 * When you have found a device, compute a session ID for it. The session
621 * ID should uniquely represent that particular device for that particular
622 * connection session since boot (i.e. if you disconnect and reconnect a
623 * device immediately after, it should be assigned a different session ID).
624 * If your OS cannot provide a unique session ID as described above,
625 * presenting a session ID of (bus_number << 8 | device_address) should
626 * be sufficient. Bus numbers and device addresses wrap and get reused,
627 * but that is an unlikely case.
629 * After computing a session ID for a device, call
630 * usbi_get_device_by_session_id(). This function checks if libusb already
631 * knows about the device, and if so, it provides you with a reference
632 * to a libusb_device structure for it.
634 * If usbi_get_device_by_session_id() returns NULL, it is time to allocate
635 * a new device structure for the device. Call usbi_alloc_device() to
636 * obtain a new libusb_device structure with reference count 1. Populate
637 * the bus_number and device_address attributes of the new device, and
638 * perform any other internal backend initialization you need to do. At
639 * this point, you should be ready to provide device descriptors and so
640 * on through the get_*_descriptor functions. Finally, call
641 * usbi_sanitize_device() to perform some final sanity checks on the
642 * device. Assuming all of the above succeeded, we can now continue.
643 * If any of the above failed, remember to unreference the device that
644 * was returned by usbi_alloc_device().
646 * At this stage we have a populated libusb_device structure (either one
647 * that was found earlier, or one that we have just allocated and
648 * populated). This can now be added to the discovered devices list
649 * using discovered_devs_append(). Note that discovered_devs_append()
650 * may reallocate the list, returning a new location for it, and also
651 * note that reallocation can fail. Your backend should handle these
652 * error conditions appropriately.
654 * This function should not generate any bus I/O and should not block.
655 * If I/O is required (e.g. reading the active configuration value), it is
656 * OK to ignore these suggestions :)
658 * This function is executed when the user wishes to retrieve a list
659 * of USB devices connected to the system.
661 * If the backend has hotplug support, this function is not used!
663 * Return 0 on success, or a LIBUSB_ERROR code on failure.
665 int (*get_device_list)(struct libusb_context *ctx,
666 struct discovered_devs **discdevs);
668 /* Apps which were written before hotplug support, may listen for
669 * hotplug events on their own and call libusb_get_device_list on
670 * device addition. In this case libusb_get_device_list will likely
671 * return a list without the new device in there, as the hotplug
672 * event thread will still be busy enumerating the device, which may
673 * take a while, or may not even have seen the event yet.
675 * To avoid this libusb_get_device_list will call this optional
676 * function for backends with hotplug support before copying
677 * ctx->usb_devs to the user. In this function the backend should
678 * ensure any pending hotplug events are fully processed before
681 * Optional, should be implemented by backends with hotplug support.
683 void (*hotplug_poll)(void);
685 /* Open a device for I/O and other USB operations. The device handle
686 * is preallocated for you, you can retrieve the device in question
687 * through handle->dev.
689 * Your backend should allocate any internal resources required for I/O
690 * and other operations so that those operations can happen (hopefully)
691 * without hiccup. This is also a good place to inform libusb that it
692 * should monitor certain file descriptors related to this device -
693 * see the usbi_add_pollfd() function.
695 * This function should not generate any bus I/O and should not block.
697 * This function is called when the user attempts to obtain a device
698 * handle for a device.
702 * - LIBUSB_ERROR_ACCESS if the user has insufficient permissions
703 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since
705 * - another LIBUSB_ERROR code on other failure
707 * Do not worry about freeing the handle on failed open, the upper layers
710 int (*open)(struct libusb_device_handle *dev_handle);
712 /* Close a device such that the handle cannot be used again. Your backend
713 * should destroy any resources that were allocated in the open path.
714 * This may also be a good place to call usbi_remove_pollfd() to inform
715 * libusb of any file descriptors associated with this device that should
716 * no longer be monitored.
718 * This function is called when the user closes a device handle.
720 void (*close)(struct libusb_device_handle *dev_handle);
722 /* Retrieve the device descriptor from a device.
724 * The descriptor should be retrieved from memory, NOT via bus I/O to the
725 * device. This means that you may have to cache it in a private structure
726 * during get_device_list enumeration. Alternatively, you may be able
727 * to retrieve it from a kernel interface (some Linux setups can do this)
728 * still without generating bus I/O.
730 * This function is expected to write DEVICE_DESC_LENGTH (18) bytes into
731 * buffer, which is guaranteed to be big enough.
733 * This function is called when sanity-checking a device before adding
734 * it to the list of discovered devices, and also when the user requests
735 * to read the device descriptor.
737 * This function is expected to return the descriptor in bus-endian format
738 * (LE). If it returns the multi-byte values in host-endian format,
739 * set the host_endian output parameter to "1".
741 * Return 0 on success or a LIBUSB_ERROR code on failure.
743 int (*get_device_descriptor)(struct libusb_device *device,
744 unsigned char *buffer, int *host_endian);
746 /* Get the ACTIVE configuration descriptor for a device.
748 * The descriptor should be retrieved from memory, NOT via bus I/O to the
749 * device. This means that you may have to cache it in a private structure
750 * during get_device_list enumeration. You may also have to keep track
751 * of which configuration is active when the user changes it.
753 * This function is expected to write len bytes of data into buffer, which
754 * is guaranteed to be big enough. If you can only do a partial write,
755 * return an error code.
757 * This function is expected to return the descriptor in bus-endian format
758 * (LE). If it returns the multi-byte values in host-endian format,
759 * set the host_endian output parameter to "1".
763 * - LIBUSB_ERROR_NOT_FOUND if the device is in unconfigured state
764 * - another LIBUSB_ERROR code on other failure
766 int (*get_active_config_descriptor)(struct libusb_device *device,
767 unsigned char *buffer, size_t len, int *host_endian);
769 /* Get a specific configuration descriptor for a device.
771 * The descriptor should be retrieved from memory, NOT via bus I/O to the
772 * device. This means that you may have to cache it in a private structure
773 * during get_device_list enumeration.
775 * The requested descriptor is expressed as a zero-based index (i.e. 0
776 * indicates that we are requesting the first descriptor). The index does
777 * not (necessarily) equal the bConfigurationValue of the configuration
780 * This function is expected to write len bytes of data into buffer, which
781 * is guaranteed to be big enough. If you can only do a partial write,
782 * return an error code.
784 * This function is expected to return the descriptor in bus-endian format
785 * (LE). If it returns the multi-byte values in host-endian format,
786 * set the host_endian output parameter to "1".
788 * Return the length read on success or a LIBUSB_ERROR code on failure.
790 int (*get_config_descriptor)(struct libusb_device *device,
791 uint8_t config_index, unsigned char *buffer, size_t len,
794 /* Like get_config_descriptor but then by bConfigurationValue instead
797 * Optional, if not present the core will call get_config_descriptor
798 * for all configs until it finds the desired bConfigurationValue.
800 * Returns a pointer to the raw-descriptor in *buffer, this memory
801 * is valid as long as device is valid.
803 * Returns the length of the returned raw-descriptor on success,
804 * or a LIBUSB_ERROR code on failure.
806 int (*get_config_descriptor_by_value)(struct libusb_device *device,
807 uint8_t bConfigurationValue, unsigned char **buffer,
810 /* Get the bConfigurationValue for the active configuration for a device.
811 * Optional. This should only be implemented if you can retrieve it from
812 * cache (don't generate I/O).
814 * If you cannot retrieve this from cache, either do not implement this
815 * function, or return LIBUSB_ERROR_NOT_SUPPORTED. This will cause
816 * libusb to retrieve the information through a standard control transfer.
818 * This function must be non-blocking.
821 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
823 * - LIBUSB_ERROR_NOT_SUPPORTED if the value cannot be retrieved without
825 * - another LIBUSB_ERROR code on other failure.
827 int (*get_configuration)(struct libusb_device_handle *dev_handle, int *config);
829 /* Set the active configuration for a device.
831 * A configuration value of -1 should put the device in unconfigured state.
833 * This function can block.
837 * - LIBUSB_ERROR_NOT_FOUND if the configuration does not exist
838 * - LIBUSB_ERROR_BUSY if interfaces are currently claimed (and hence
839 * configuration cannot be changed)
840 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
842 * - another LIBUSB_ERROR code on other failure.
844 int (*set_configuration)(struct libusb_device_handle *dev_handle, int config);
846 /* Claim an interface. When claimed, the application can then perform
847 * I/O to an interface's endpoints.
849 * This function should not generate any bus I/O and should not block.
850 * Interface claiming is a logical operation that simply ensures that
851 * no other drivers/applications are using the interface, and after
852 * claiming, no other drivers/applications can use the interface because
857 * - LIBUSB_ERROR_NOT_FOUND if the interface does not exist
858 * - LIBUSB_ERROR_BUSY if the interface is in use by another driver/app
859 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
861 * - another LIBUSB_ERROR code on other failure
863 int (*claim_interface)(struct libusb_device_handle *dev_handle, int interface_number);
865 /* Release a previously claimed interface.
867 * This function should also generate a SET_INTERFACE control request,
868 * resetting the alternate setting of that interface to 0. It's OK for
869 * this function to block as a result.
871 * You will only ever be asked to release an interface which was
872 * successfully claimed earlier.
876 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
878 * - another LIBUSB_ERROR code on other failure
880 int (*release_interface)(struct libusb_device_handle *dev_handle, int interface_number);
882 /* Set the alternate setting for an interface.
884 * You will only ever be asked to set the alternate setting for an
885 * interface which was successfully claimed earlier.
887 * It's OK for this function to block.
891 * - LIBUSB_ERROR_NOT_FOUND if the alternate setting does not exist
892 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
894 * - another LIBUSB_ERROR code on other failure
896 int (*set_interface_altsetting)(struct libusb_device_handle *dev_handle,
897 int interface_number, int altsetting);
899 /* Clear a halt/stall condition on an endpoint.
901 * It's OK for this function to block.
905 * - LIBUSB_ERROR_NOT_FOUND if the endpoint does not exist
906 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
908 * - another LIBUSB_ERROR code on other failure
910 int (*clear_halt)(struct libusb_device_handle *dev_handle,
911 unsigned char endpoint);
913 /* Perform a USB port reset to reinitialize a device.
915 * If possible, the device handle should still be usable after the reset
916 * completes, assuming that the device descriptors did not change during
917 * reset and all previous interface state can be restored.
919 * If something changes, or you cannot easily locate/verify the resetted
920 * device, return LIBUSB_ERROR_NOT_FOUND. This prompts the application
921 * to close the old handle and re-enumerate the device.
925 * - LIBUSB_ERROR_NOT_FOUND if re-enumeration is required, or if the device
926 * has been disconnected since it was opened
927 * - another LIBUSB_ERROR code on other failure
929 int (*reset_device)(struct libusb_device_handle *dev_handle);
931 /* Alloc num_streams usb3 bulk streams on the passed in endpoints */
932 int (*alloc_streams)(struct libusb_device_handle *dev_handle,
933 uint32_t num_streams, unsigned char *endpoints, int num_endpoints);
935 /* Free usb3 bulk streams allocated with alloc_streams */
936 int (*free_streams)(struct libusb_device_handle *dev_handle,
937 unsigned char *endpoints, int num_endpoints);
939 /* Allocate persistent DMA memory for the given device, suitable for
940 * zerocopy. May return NULL on failure. Optional to implement.
942 unsigned char *(*dev_mem_alloc)(struct libusb_device_handle *handle,
945 /* Free memory allocated by dev_mem_alloc. */
946 int (*dev_mem_free)(struct libusb_device_handle *handle,
947 unsigned char *buffer, size_t len);
949 /* Determine if a kernel driver is active on an interface. Optional.
951 * The presence of a kernel driver on an interface indicates that any
952 * calls to claim_interface would fail with the LIBUSB_ERROR_BUSY code.
955 * - 0 if no driver is active
956 * - 1 if a driver is active
957 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
959 * - another LIBUSB_ERROR code on other failure
961 int (*kernel_driver_active)(struct libusb_device_handle *dev_handle,
962 int interface_number);
964 /* Detach a kernel driver from an interface. Optional.
966 * After detaching a kernel driver, the interface should be available
971 * - LIBUSB_ERROR_NOT_FOUND if no kernel driver was active
972 * - LIBUSB_ERROR_INVALID_PARAM if the interface does not exist
973 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
975 * - another LIBUSB_ERROR code on other failure
977 int (*detach_kernel_driver)(struct libusb_device_handle *dev_handle,
978 int interface_number);
980 /* Attach a kernel driver to an interface. Optional.
982 * Reattach a kernel driver to the device.
986 * - LIBUSB_ERROR_NOT_FOUND if no kernel driver was active
987 * - LIBUSB_ERROR_INVALID_PARAM if the interface does not exist
988 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
990 * - LIBUSB_ERROR_BUSY if a program or driver has claimed the interface,
991 * preventing reattachment
992 * - another LIBUSB_ERROR code on other failure
994 int (*attach_kernel_driver)(struct libusb_device_handle *dev_handle,
995 int interface_number);
997 /* Destroy a device. Optional.
999 * This function is called when the last reference to a device is
1000 * destroyed. It should free any resources allocated in the get_device_list
1003 void (*destroy_device)(struct libusb_device *dev);
1005 /* Submit a transfer. Your implementation should take the transfer,
1006 * morph it into whatever form your platform requires, and submit it
1009 * This function must not block.
1011 * This function gets called with the flying_transfers_lock locked!
1015 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
1016 * - another LIBUSB_ERROR code on other failure
1018 int (*submit_transfer)(struct usbi_transfer *itransfer);
1020 /* Cancel a previously submitted transfer.
1022 * This function must not block. The transfer cancellation must complete
1023 * later, resulting in a call to usbi_handle_transfer_cancellation()
1024 * from the context of handle_events.
1026 int (*cancel_transfer)(struct usbi_transfer *itransfer);
1028 /* Clear a transfer as if it has completed or cancelled, but do not
1029 * report any completion/cancellation to the library. You should free
1030 * all private data from the transfer as if you were just about to report
1031 * completion or cancellation.
1033 * This function might seem a bit out of place. It is used when libusb
1034 * detects a disconnected device - it calls this function for all pending
1035 * transfers before reporting completion (with the disconnect code) to
1036 * the user. Maybe we can improve upon this internal interface in future.
1038 void (*clear_transfer_priv)(struct usbi_transfer *itransfer);
1040 /* Handle any pending events on file descriptors. Optional.
1042 * Provide this function when file descriptors directly indicate device
1043 * or transfer activity. If your backend does not have such file descriptors,
1044 * implement the handle_transfer_completion function below.
1046 * This involves monitoring any active transfers and processing their
1047 * completion or cancellation.
1049 * The function is passed an array of pollfd structures (size nfds)
1050 * as a result of the poll() system call. The num_ready parameter
1051 * indicates the number of file descriptors that have reported events
1052 * (i.e. the poll() return value). This should be enough information
1053 * for you to determine which actions need to be taken on the currently
1056 * For any cancelled transfers, call usbi_handle_transfer_cancellation().
1057 * For completed transfers, call usbi_handle_transfer_completion().
1058 * For control/bulk/interrupt transfers, populate the "transferred"
1059 * element of the appropriate usbi_transfer structure before calling the
1060 * above functions. For isochronous transfers, populate the status and
1061 * transferred fields of the iso packet descriptors of the transfer.
1063 * This function should also be able to detect disconnection of the
1064 * device, reporting that situation with usbi_handle_disconnect().
1066 * When processing an event related to a transfer, you probably want to
1067 * take usbi_transfer.lock to prevent races. See the documentation for
1068 * the usbi_transfer structure.
1070 * Return 0 on success, or a LIBUSB_ERROR code on failure.
1072 int (*handle_events)(struct libusb_context *ctx,
1073 struct pollfd *fds, POLL_NFDS_TYPE nfds, int num_ready);
1075 /* Handle transfer completion. Optional.
1077 * Provide this function when there are no file descriptors available
1078 * that directly indicate device or transfer activity. If your backend does
1079 * have such file descriptors, implement the handle_events function above.
1081 * Your backend must tell the library when a transfer has completed by
1082 * calling usbi_signal_transfer_completion(). You should store any private
1083 * information about the transfer and its completion status in the transfer's
1084 * private backend data.
1086 * During event handling, this function will be called on each transfer for
1087 * which usbi_signal_transfer_completion() was called.
1089 * For any cancelled transfers, call usbi_handle_transfer_cancellation().
1090 * For completed transfers, call usbi_handle_transfer_completion().
1091 * For control/bulk/interrupt transfers, populate the "transferred"
1092 * element of the appropriate usbi_transfer structure before calling the
1093 * above functions. For isochronous transfers, populate the status and
1094 * transferred fields of the iso packet descriptors of the transfer.
1096 * Return 0 on success, or a LIBUSB_ERROR code on failure.
1098 int (*handle_transfer_completion)(struct usbi_transfer *itransfer);
1100 /* Get time from specified clock. At least two clocks must be implemented
1101 by the backend: USBI_CLOCK_REALTIME, and USBI_CLOCK_MONOTONIC.
1103 Description of clocks:
1104 USBI_CLOCK_REALTIME : clock returns time since system epoch.
1105 USBI_CLOCK_MONOTONIC: clock returns time since unspecified start
1106 time (usually boot).
1108 int (*clock_gettime)(int clkid, struct timespec *tp);
1110 #ifdef USBI_TIMERFD_AVAILABLE
1111 /* clock ID of the clock that should be used for timerfd */
1112 clockid_t (*get_timerfd_clockid)(void);
1115 /* Number of bytes to reserve for per-device private backend data.
1116 * This private data area is accessible through the "os_priv" field of
1117 * struct libusb_device. */
1118 size_t device_priv_size;
1120 /* Number of bytes to reserve for per-handle private backend data.
1121 * This private data area is accessible through the "os_priv" field of
1122 * struct libusb_device. */
1123 size_t device_handle_priv_size;
1125 /* Number of bytes to reserve for per-transfer private backend data.
1126 * This private data area is accessible by calling
1127 * usbi_transfer_get_os_priv() on the appropriate usbi_transfer instance.
1129 size_t transfer_priv_size;
1132 extern const struct usbi_os_backend usbi_backend;
1134 extern struct list_head active_contexts_list;
1135 extern usbi_mutex_static_t active_contexts_lock;