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 CLAMP(val, min, max) ((val) < (min) ? (min) : ((val) > (max) ? (max) : (val)))
185 #define MIN(a, b) ((a) < (b) ? (a) : (b))
188 #define MAX(a, b) ((a) > (b) ? (a) : (b))
191 #define TIMESPEC_IS_SET(ts) ((ts)->tv_sec != 0 || (ts)->tv_nsec != 0)
193 #if defined(_WIN32) || defined(__CYGWIN__) || defined(_WIN32_WCE)
194 #define TIMEVAL_TV_SEC_TYPE long
196 #define TIMEVAL_TV_SEC_TYPE time_t
199 /* Some platforms don't have this define */
200 #ifndef TIMESPEC_TO_TIMEVAL
201 #define TIMESPEC_TO_TIMEVAL(tv, ts) \
203 (tv)->tv_sec = (TIMEVAL_TV_SEC_TYPE) (ts)->tv_sec; \
204 (tv)->tv_usec = (ts)->tv_nsec / 1000; \
208 #ifdef ENABLE_LOGGING
210 #if defined(_MSC_VER) && (_MSC_VER < 1900)
211 #define snprintf usbi_snprintf
212 #define vsnprintf usbi_vsnprintf
213 int usbi_snprintf(char *dst, size_t size, const char *format, ...);
214 int usbi_vsnprintf(char *dst, size_t size, const char *format, va_list ap);
215 #define LIBUSB_PRINTF_WIN32
216 #endif /* defined(_MSC_VER) && (_MSC_VER < 1900) */
218 void usbi_log(struct libusb_context *ctx, enum libusb_log_level level,
219 const char *function, const char *format, ...);
221 void usbi_log_v(struct libusb_context *ctx, enum libusb_log_level level,
222 const char *function, const char *format, va_list args);
224 #if !defined(_MSC_VER) || (_MSC_VER >= 1400)
226 #define _usbi_log(ctx, level, ...) usbi_log(ctx, level, __FUNCTION__, __VA_ARGS__)
228 #define usbi_err(ctx, ...) _usbi_log(ctx, LIBUSB_LOG_LEVEL_ERROR, __VA_ARGS__)
229 #define usbi_warn(ctx, ...) _usbi_log(ctx, LIBUSB_LOG_LEVEL_WARNING, __VA_ARGS__)
230 #define usbi_info(ctx, ...) _usbi_log(ctx, LIBUSB_LOG_LEVEL_INFO, __VA_ARGS__)
231 #define usbi_dbg(...) _usbi_log(NULL, LIBUSB_LOG_LEVEL_DEBUG, __VA_ARGS__)
233 #else /* !defined(_MSC_VER) || (_MSC_VER >= 1400) */
235 #define LOG_BODY(ctxt, level) \
238 va_start(args, format); \
239 usbi_log_v(ctxt, level, "", format, args); \
243 static inline void usbi_err(struct libusb_context *ctx, const char *format, ...)
244 LOG_BODY(ctx, LIBUSB_LOG_LEVEL_ERROR)
245 static inline void usbi_warn(struct libusb_context *ctx, const char *format, ...)
246 LOG_BODY(ctx, LIBUSB_LOG_LEVEL_WARNING)
247 static inline void usbi_info(struct libusb_context *ctx, const char *format, ...)
248 LOG_BODY(ctx, LIBUSB_LOG_LEVEL_INFO)
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 #else /* ENABLE_LOGGING */
256 #define usbi_err(ctx, ...) do { (void)ctx; } while (0)
257 #define usbi_warn(ctx, ...) do { (void)ctx; } while (0)
258 #define usbi_info(ctx, ...) do { (void)ctx; } while (0)
259 #define usbi_dbg(...) do {} while (0)
261 #endif /* ENABLE_LOGGING */
263 #define USBI_GET_CONTEXT(ctx) \
266 (ctx) = usbi_default_context; \
269 #define DEVICE_CTX(dev) ((dev)->ctx)
270 #define HANDLE_CTX(handle) (DEVICE_CTX((handle)->dev))
271 #define TRANSFER_CTX(transfer) (HANDLE_CTX((transfer)->dev_handle))
272 #define ITRANSFER_CTX(transfer) \
273 (TRANSFER_CTX(USBI_TRANSFER_TO_LIBUSB_TRANSFER(transfer)))
275 #define IS_EPIN(ep) (0 != ((ep) & LIBUSB_ENDPOINT_IN))
276 #define IS_EPOUT(ep) (!IS_EPIN(ep))
277 #define IS_XFERIN(xfer) (0 != ((xfer)->endpoint & LIBUSB_ENDPOINT_IN))
278 #define IS_XFEROUT(xfer) (!IS_XFERIN(xfer))
280 /* Internal abstraction for thread synchronization */
281 #if defined(THREADS_POSIX)
282 #include "os/threads_posix.h"
283 #elif defined(OS_WINDOWS) || defined(OS_WINCE)
284 #include "os/threads_windows.h"
287 extern struct libusb_context *usbi_default_context;
289 /* Forward declaration for use in context (fully defined inside poll abstraction) */
292 struct libusb_context {
293 #if defined(ENABLE_LOGGING) && !defined(ENABLE_DEBUG_LOGGING)
294 enum libusb_log_level debug;
298 /* internal event pipe, used for signalling occurrence of an internal event. */
301 struct list_head usb_devs;
302 usbi_mutex_t usb_devs_lock;
304 /* A list of open handles. Backends are free to traverse this if required.
306 struct list_head open_devs;
307 usbi_mutex_t open_devs_lock;
309 /* A list of registered hotplug callbacks */
310 struct list_head hotplug_cbs;
311 libusb_hotplug_callback_handle next_hotplug_cb_handle;
312 usbi_mutex_t hotplug_cbs_lock;
314 /* this is a list of in-flight transfer handles, sorted by timeout
315 * expiration. URBs to timeout the soonest are placed at the beginning of
316 * the list, URBs that will time out later are placed after, and urbs with
317 * infinite timeout are always placed at the very end. */
318 struct list_head flying_transfers;
319 /* Note paths taking both this and usbi_transfer->lock must always
320 * take this lock first */
321 usbi_mutex_t flying_transfers_lock;
323 /* user callbacks for pollfd changes */
324 libusb_pollfd_added_cb fd_added_cb;
325 libusb_pollfd_removed_cb fd_removed_cb;
326 void *fd_cb_user_data;
328 /* ensures that only one thread is handling events at any one time */
329 usbi_mutex_t events_lock;
331 /* used to see if there is an active thread doing event handling */
332 int event_handler_active;
334 /* A thread-local storage key to track which thread is performing event
336 usbi_tls_key_t event_handling_key;
338 /* used to wait for event completion in threads other than the one that is
340 usbi_mutex_t event_waiters_lock;
341 usbi_cond_t event_waiters_cond;
343 /* A lock to protect internal context event data. */
344 usbi_mutex_t event_data_lock;
346 /* A bitmask of flags that are set to indicate specific events that need to
347 * be handled. Protected by event_data_lock. */
348 unsigned int event_flags;
350 /* A counter that is set when we want to interrupt and prevent event handling,
351 * in order to safely close a device. Protected by event_data_lock. */
352 unsigned int device_close;
354 /* list and count of poll fds and an array of poll fd structures that is
355 * (re)allocated as necessary prior to polling. Protected by event_data_lock. */
356 struct list_head ipollfds;
357 struct pollfd *pollfds;
358 POLL_NFDS_TYPE pollfds_cnt;
360 /* A list of pending hotplug messages. Protected by event_data_lock. */
361 struct list_head hotplug_msgs;
363 /* A list of pending completed transfers. Protected by event_data_lock. */
364 struct list_head completed_transfers;
366 #ifdef USBI_TIMERFD_AVAILABLE
367 /* used for timeout handling, if supported by OS.
368 * this timerfd is maintained to trigger on the next pending timeout */
372 struct list_head list;
374 PTR_ALIGNED unsigned char os_priv[ZERO_SIZED_ARRAY];
377 enum usbi_event_flags {
378 /* The list of pollfds has been modified */
379 USBI_EVENT_POLLFDS_MODIFIED = 1 << 0,
381 /* The user has interrupted the event handler */
382 USBI_EVENT_USER_INTERRUPT = 1 << 1,
384 /* A hotplug callback deregistration is pending */
385 USBI_EVENT_HOTPLUG_CB_DEREGISTERED = 1 << 2,
388 /* Macros for managing event handling state */
389 #define usbi_handling_events(ctx) \
390 (usbi_tls_key_get((ctx)->event_handling_key) != NULL)
392 #define usbi_start_event_handling(ctx) \
393 usbi_tls_key_set((ctx)->event_handling_key, ctx)
395 #define usbi_end_event_handling(ctx) \
396 usbi_tls_key_set((ctx)->event_handling_key, NULL)
398 /* Update the following macro if new event sources are added */
399 #define usbi_pending_events(ctx) \
400 ((ctx)->event_flags || (ctx)->device_close \
401 || !list_empty(&(ctx)->hotplug_msgs) || !list_empty(&(ctx)->completed_transfers))
403 #ifdef USBI_TIMERFD_AVAILABLE
404 #define usbi_using_timerfd(ctx) ((ctx)->timerfd >= 0)
406 #define usbi_using_timerfd(ctx) (0)
409 struct libusb_device {
410 /* lock protects refcnt, everything else is finalized at initialization
415 struct libusb_context *ctx;
419 struct libusb_device* parent_dev;
420 uint8_t device_address;
421 uint8_t num_configurations;
422 enum libusb_speed speed;
424 struct list_head list;
425 unsigned long session_data;
427 struct libusb_device_descriptor device_descriptor;
430 PTR_ALIGNED unsigned char os_priv[ZERO_SIZED_ARRAY];
433 struct libusb_device_handle {
434 /* lock protects claimed_interfaces */
436 unsigned long claimed_interfaces;
438 struct list_head list;
439 struct libusb_device *dev;
440 int auto_detach_kernel_driver;
442 PTR_ALIGNED unsigned char os_priv[ZERO_SIZED_ARRAY];
446 USBI_CLOCK_MONOTONIC,
450 /* in-memory transfer layout:
452 * 1. struct usbi_transfer
453 * 2. struct libusb_transfer (which includes iso packets) [variable size]
454 * 3. os private data [variable size]
456 * from a libusb_transfer, you can get the usbi_transfer by rewinding the
457 * appropriate number of bytes.
458 * the usbi_transfer includes the number of allocated packets, so you can
459 * determine the size of the transfer and hence the start and length of the
463 struct usbi_transfer {
465 struct list_head list;
466 struct list_head completed_list;
467 struct timeval timeout;
470 uint8_t state_flags; /* Protected by usbi_transfer->lock */
471 uint8_t timeout_flags; /* Protected by the flying_stransfers_lock */
473 /* this lock is held during libusb_submit_transfer() and
474 * libusb_cancel_transfer() (allowing the OS backend to prevent duplicate
475 * cancellation, submission-during-cancellation, etc). the OS backend
476 * should also take this lock in the handle_events path, to prevent the user
477 * cancelling the transfer from another thread while you are processing
478 * its completion (presumably there would be races within your OS backend
479 * if this were possible).
480 * Note paths taking both this and the flying_transfers_lock must
481 * always take the flying_transfers_lock first */
485 enum usbi_transfer_state_flags {
486 /* Transfer successfully submitted by backend */
487 USBI_TRANSFER_IN_FLIGHT = 1 << 0,
489 /* Cancellation was requested via libusb_cancel_transfer() */
490 USBI_TRANSFER_CANCELLING = 1 << 1,
492 /* Operation on the transfer failed because the device disappeared */
493 USBI_TRANSFER_DEVICE_DISAPPEARED = 1 << 2,
496 enum usbi_transfer_timeout_flags {
497 /* Set by backend submit_transfer() if the OS handles timeout */
498 USBI_TRANSFER_OS_HANDLES_TIMEOUT = 1 << 0,
500 /* The transfer timeout has been handled */
501 USBI_TRANSFER_TIMEOUT_HANDLED = 1 << 1,
503 /* The transfer timeout was successfully processed */
504 USBI_TRANSFER_TIMED_OUT = 1 << 2,
507 #define USBI_TRANSFER_TO_LIBUSB_TRANSFER(transfer) \
508 ((struct libusb_transfer *)(((unsigned char *)(transfer)) \
509 + sizeof(struct usbi_transfer)))
510 #define LIBUSB_TRANSFER_TO_USBI_TRANSFER(transfer) \
511 ((struct usbi_transfer *)(((unsigned char *)(transfer)) \
512 - sizeof(struct usbi_transfer)))
514 static inline void *usbi_transfer_get_os_priv(struct usbi_transfer *transfer)
516 return ((unsigned char *)transfer) + sizeof(struct usbi_transfer)
517 + sizeof(struct libusb_transfer)
518 + (transfer->num_iso_packets
519 * sizeof(struct libusb_iso_packet_descriptor));
524 /* All standard descriptors have these 2 fields in common */
525 struct usb_descriptor_header {
527 uint8_t bDescriptorType;
530 /* shared data and functions */
532 int usbi_io_init(struct libusb_context *ctx);
533 void usbi_io_exit(struct libusb_context *ctx);
535 struct libusb_device *usbi_alloc_device(struct libusb_context *ctx,
536 unsigned long session_id);
537 struct libusb_device *usbi_get_device_by_session_id(struct libusb_context *ctx,
538 unsigned long session_id);
539 int usbi_sanitize_device(struct libusb_device *dev);
540 void usbi_handle_disconnect(struct libusb_device_handle *dev_handle);
542 int usbi_handle_transfer_completion(struct usbi_transfer *itransfer,
543 enum libusb_transfer_status status);
544 int usbi_handle_transfer_cancellation(struct usbi_transfer *transfer);
545 void usbi_signal_transfer_completion(struct usbi_transfer *transfer);
547 int usbi_parse_descriptor(const unsigned char *source, const char *descriptor,
548 void *dest, int host_endian);
549 int usbi_device_cache_descriptor(libusb_device *dev);
550 int usbi_get_config_index_by_value(struct libusb_device *dev,
551 uint8_t bConfigurationValue, int *idx);
553 void usbi_connect_device (struct libusb_device *dev);
554 void usbi_disconnect_device (struct libusb_device *dev);
556 int usbi_signal_event(struct libusb_context *ctx);
557 int usbi_clear_event(struct libusb_context *ctx);
559 /* Internal abstraction for poll (needs struct usbi_transfer on Windows) */
560 #if defined(OS_LINUX) || defined(OS_DARWIN) || defined(OS_OPENBSD) || defined(OS_NETBSD) ||\
561 defined(OS_HAIKU) || defined(OS_SUNOS)
563 #include "os/poll_posix.h"
564 #elif defined(OS_WINDOWS) || defined(OS_WINCE)
565 #include "os/poll_windows.h"
569 /* must come first */
570 struct libusb_pollfd pollfd;
572 struct list_head list;
575 int usbi_add_pollfd(struct libusb_context *ctx, int fd, short events);
576 void usbi_remove_pollfd(struct libusb_context *ctx, int fd);
578 /* device discovery */
580 /* we traverse usbfs without knowing how many devices we are going to find.
581 * so we create this discovered_devs model which is similar to a linked-list
582 * which grows when required. it can be freed once discovery has completed,
583 * eliminating the need for a list node in the libusb_device structure
585 struct discovered_devs {
588 struct libusb_device *devices[ZERO_SIZED_ARRAY];
591 struct discovered_devs *discovered_devs_append(
592 struct discovered_devs *discdevs, struct libusb_device *dev);
596 /* This is the interface that OS backends need to implement.
597 * All fields are mandatory, except ones explicitly noted as optional. */
598 struct usbi_os_backend {
599 /* A human-readable name for your backend, e.g. "Linux usbfs" */
602 /* Binary mask for backend specific capabilities */
605 /* Perform initialization of your backend. You might use this function
606 * to determine specific capabilities of the system, allocate required
607 * data structures for later, etc.
609 * This function is called when a libusb user initializes the library
612 * Return 0 on success, or a LIBUSB_ERROR code on failure.
614 int (*init)(struct libusb_context *ctx);
616 /* Deinitialization. Optional. This function should destroy anything
617 * that was set up by init.
619 * This function is called when the user deinitializes the library.
621 void (*exit)(struct libusb_context *ctx);
623 /* Set a backend-specific option. Optional.
625 * This function is called when the user calls libusb_set_option() and
626 * the option is not handled by the core library.
628 * Return 0 on success, or a LIBUSB_ERROR code on failure.
630 int (*set_option)(struct libusb_context *ctx, enum libusb_option option,
633 /* Enumerate all the USB devices on the system, returning them in a list
634 * of discovered devices.
636 * Your implementation should enumerate all devices on the system,
637 * regardless of whether they have been seen before or not.
639 * When you have found a device, compute a session ID for it. The session
640 * ID should uniquely represent that particular device for that particular
641 * connection session since boot (i.e. if you disconnect and reconnect a
642 * device immediately after, it should be assigned a different session ID).
643 * If your OS cannot provide a unique session ID as described above,
644 * presenting a session ID of (bus_number << 8 | device_address) should
645 * be sufficient. Bus numbers and device addresses wrap and get reused,
646 * but that is an unlikely case.
648 * After computing a session ID for a device, call
649 * usbi_get_device_by_session_id(). This function checks if libusb already
650 * knows about the device, and if so, it provides you with a reference
651 * to a libusb_device structure for it.
653 * If usbi_get_device_by_session_id() returns NULL, it is time to allocate
654 * a new device structure for the device. Call usbi_alloc_device() to
655 * obtain a new libusb_device structure with reference count 1. Populate
656 * the bus_number and device_address attributes of the new device, and
657 * perform any other internal backend initialization you need to do. At
658 * this point, you should be ready to provide device descriptors and so
659 * on through the get_*_descriptor functions. Finally, call
660 * usbi_sanitize_device() to perform some final sanity checks on the
661 * device. Assuming all of the above succeeded, we can now continue.
662 * If any of the above failed, remember to unreference the device that
663 * was returned by usbi_alloc_device().
665 * At this stage we have a populated libusb_device structure (either one
666 * that was found earlier, or one that we have just allocated and
667 * populated). This can now be added to the discovered devices list
668 * using discovered_devs_append(). Note that discovered_devs_append()
669 * may reallocate the list, returning a new location for it, and also
670 * note that reallocation can fail. Your backend should handle these
671 * error conditions appropriately.
673 * This function should not generate any bus I/O and should not block.
674 * If I/O is required (e.g. reading the active configuration value), it is
675 * OK to ignore these suggestions :)
677 * This function is executed when the user wishes to retrieve a list
678 * of USB devices connected to the system.
680 * If the backend has hotplug support, this function is not used!
682 * Return 0 on success, or a LIBUSB_ERROR code on failure.
684 int (*get_device_list)(struct libusb_context *ctx,
685 struct discovered_devs **discdevs);
687 /* Apps which were written before hotplug support, may listen for
688 * hotplug events on their own and call libusb_get_device_list on
689 * device addition. In this case libusb_get_device_list will likely
690 * return a list without the new device in there, as the hotplug
691 * event thread will still be busy enumerating the device, which may
692 * take a while, or may not even have seen the event yet.
694 * To avoid this libusb_get_device_list will call this optional
695 * function for backends with hotplug support before copying
696 * ctx->usb_devs to the user. In this function the backend should
697 * ensure any pending hotplug events are fully processed before
700 * Optional, should be implemented by backends with hotplug support.
702 void (*hotplug_poll)(void);
704 /* Open a device for I/O and other USB operations. The device handle
705 * is preallocated for you, you can retrieve the device in question
706 * through handle->dev.
708 * Your backend should allocate any internal resources required for I/O
709 * and other operations so that those operations can happen (hopefully)
710 * without hiccup. This is also a good place to inform libusb that it
711 * should monitor certain file descriptors related to this device -
712 * see the usbi_add_pollfd() function.
714 * This function should not generate any bus I/O and should not block.
716 * This function is called when the user attempts to obtain a device
717 * handle for a device.
721 * - LIBUSB_ERROR_ACCESS if the user has insufficient permissions
722 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since
724 * - another LIBUSB_ERROR code on other failure
726 * Do not worry about freeing the handle on failed open, the upper layers
729 int (*open)(struct libusb_device_handle *dev_handle);
731 /* Close a device such that the handle cannot be used again. Your backend
732 * should destroy any resources that were allocated in the open path.
733 * This may also be a good place to call usbi_remove_pollfd() to inform
734 * libusb of any file descriptors associated with this device that should
735 * no longer be monitored.
737 * This function is called when the user closes a device handle.
739 void (*close)(struct libusb_device_handle *dev_handle);
741 /* Retrieve the device descriptor from a device.
743 * The descriptor should be retrieved from memory, NOT via bus I/O to the
744 * device. This means that you may have to cache it in a private structure
745 * during get_device_list enumeration. Alternatively, you may be able
746 * to retrieve it from a kernel interface (some Linux setups can do this)
747 * still without generating bus I/O.
749 * This function is expected to write DEVICE_DESC_LENGTH (18) bytes into
750 * buffer, which is guaranteed to be big enough.
752 * This function is called when sanity-checking a device before adding
753 * it to the list of discovered devices, and also when the user requests
754 * to read the device descriptor.
756 * This function is expected to return the descriptor in bus-endian format
757 * (LE). If it returns the multi-byte values in host-endian format,
758 * set the host_endian output parameter to "1".
760 * Return 0 on success or a LIBUSB_ERROR code on failure.
762 int (*get_device_descriptor)(struct libusb_device *device,
763 unsigned char *buffer, int *host_endian);
765 /* Get the ACTIVE configuration descriptor for a device.
767 * The descriptor should be retrieved from memory, NOT via bus I/O to the
768 * device. This means that you may have to cache it in a private structure
769 * during get_device_list enumeration. You may also have to keep track
770 * of which configuration is active when the user changes it.
772 * This function is expected to write len bytes of data into buffer, which
773 * is guaranteed to be big enough. If you can only do a partial write,
774 * return an error code.
776 * This function is expected to return the descriptor in bus-endian format
777 * (LE). If it returns the multi-byte values in host-endian format,
778 * set the host_endian output parameter to "1".
782 * - LIBUSB_ERROR_NOT_FOUND if the device is in unconfigured state
783 * - another LIBUSB_ERROR code on other failure
785 int (*get_active_config_descriptor)(struct libusb_device *device,
786 unsigned char *buffer, size_t len, int *host_endian);
788 /* Get a specific configuration descriptor for a device.
790 * The descriptor should be retrieved from memory, NOT via bus I/O to the
791 * device. This means that you may have to cache it in a private structure
792 * during get_device_list enumeration.
794 * The requested descriptor is expressed as a zero-based index (i.e. 0
795 * indicates that we are requesting the first descriptor). The index does
796 * not (necessarily) equal the bConfigurationValue of the configuration
799 * This function is expected to write len bytes of data into buffer, which
800 * is guaranteed to be big enough. If you can only do a partial write,
801 * return an error code.
803 * This function is expected to return the descriptor in bus-endian format
804 * (LE). If it returns the multi-byte values in host-endian format,
805 * set the host_endian output parameter to "1".
807 * Return the length read on success or a LIBUSB_ERROR code on failure.
809 int (*get_config_descriptor)(struct libusb_device *device,
810 uint8_t config_index, unsigned char *buffer, size_t len,
813 /* Like get_config_descriptor but then by bConfigurationValue instead
816 * Optional, if not present the core will call get_config_descriptor
817 * for all configs until it finds the desired bConfigurationValue.
819 * Returns a pointer to the raw-descriptor in *buffer, this memory
820 * is valid as long as device is valid.
822 * Returns the length of the returned raw-descriptor on success,
823 * or a LIBUSB_ERROR code on failure.
825 int (*get_config_descriptor_by_value)(struct libusb_device *device,
826 uint8_t bConfigurationValue, unsigned char **buffer,
829 /* Get the bConfigurationValue for the active configuration for a device.
830 * Optional. This should only be implemented if you can retrieve it from
831 * cache (don't generate I/O).
833 * If you cannot retrieve this from cache, either do not implement this
834 * function, or return LIBUSB_ERROR_NOT_SUPPORTED. This will cause
835 * libusb to retrieve the information through a standard control transfer.
837 * This function must be non-blocking.
840 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
842 * - LIBUSB_ERROR_NOT_SUPPORTED if the value cannot be retrieved without
844 * - another LIBUSB_ERROR code on other failure.
846 int (*get_configuration)(struct libusb_device_handle *dev_handle, int *config);
848 /* Set the active configuration for a device.
850 * A configuration value of -1 should put the device in unconfigured state.
852 * This function can block.
856 * - LIBUSB_ERROR_NOT_FOUND if the configuration does not exist
857 * - LIBUSB_ERROR_BUSY if interfaces are currently claimed (and hence
858 * configuration cannot be changed)
859 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
861 * - another LIBUSB_ERROR code on other failure.
863 int (*set_configuration)(struct libusb_device_handle *dev_handle, int config);
865 /* Claim an interface. When claimed, the application can then perform
866 * I/O to an interface's endpoints.
868 * This function should not generate any bus I/O and should not block.
869 * Interface claiming is a logical operation that simply ensures that
870 * no other drivers/applications are using the interface, and after
871 * claiming, no other drivers/applications can use the interface because
876 * - LIBUSB_ERROR_NOT_FOUND if the interface does not exist
877 * - LIBUSB_ERROR_BUSY if the interface is in use by another driver/app
878 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
880 * - another LIBUSB_ERROR code on other failure
882 int (*claim_interface)(struct libusb_device_handle *dev_handle, int interface_number);
884 /* Release a previously claimed interface.
886 * This function should also generate a SET_INTERFACE control request,
887 * resetting the alternate setting of that interface to 0. It's OK for
888 * this function to block as a result.
890 * You will only ever be asked to release an interface which was
891 * successfully claimed earlier.
895 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
897 * - another LIBUSB_ERROR code on other failure
899 int (*release_interface)(struct libusb_device_handle *dev_handle, int interface_number);
901 /* Set the alternate setting for an interface.
903 * You will only ever be asked to set the alternate setting for an
904 * interface which was successfully claimed earlier.
906 * It's OK for this function to block.
910 * - LIBUSB_ERROR_NOT_FOUND if the alternate setting does not exist
911 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
913 * - another LIBUSB_ERROR code on other failure
915 int (*set_interface_altsetting)(struct libusb_device_handle *dev_handle,
916 int interface_number, int altsetting);
918 /* Clear a halt/stall condition on an endpoint.
920 * It's OK for this function to block.
924 * - LIBUSB_ERROR_NOT_FOUND if the endpoint does not exist
925 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
927 * - another LIBUSB_ERROR code on other failure
929 int (*clear_halt)(struct libusb_device_handle *dev_handle,
930 unsigned char endpoint);
932 /* Perform a USB port reset to reinitialize a device.
934 * If possible, the device handle should still be usable after the reset
935 * completes, assuming that the device descriptors did not change during
936 * reset and all previous interface state can be restored.
938 * If something changes, or you cannot easily locate/verify the resetted
939 * device, return LIBUSB_ERROR_NOT_FOUND. This prompts the application
940 * to close the old handle and re-enumerate the device.
944 * - LIBUSB_ERROR_NOT_FOUND if re-enumeration is required, or if the device
945 * has been disconnected since it was opened
946 * - another LIBUSB_ERROR code on other failure
948 int (*reset_device)(struct libusb_device_handle *dev_handle);
950 /* Alloc num_streams usb3 bulk streams on the passed in endpoints */
951 int (*alloc_streams)(struct libusb_device_handle *dev_handle,
952 uint32_t num_streams, unsigned char *endpoints, int num_endpoints);
954 /* Free usb3 bulk streams allocated with alloc_streams */
955 int (*free_streams)(struct libusb_device_handle *dev_handle,
956 unsigned char *endpoints, int num_endpoints);
958 /* Allocate persistent DMA memory for the given device, suitable for
959 * zerocopy. May return NULL on failure. Optional to implement.
961 unsigned char *(*dev_mem_alloc)(struct libusb_device_handle *handle,
964 /* Free memory allocated by dev_mem_alloc. */
965 int (*dev_mem_free)(struct libusb_device_handle *handle,
966 unsigned char *buffer, size_t len);
968 /* Determine if a kernel driver is active on an interface. Optional.
970 * The presence of a kernel driver on an interface indicates that any
971 * calls to claim_interface would fail with the LIBUSB_ERROR_BUSY code.
974 * - 0 if no driver is active
975 * - 1 if a driver is active
976 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
978 * - another LIBUSB_ERROR code on other failure
980 int (*kernel_driver_active)(struct libusb_device_handle *dev_handle,
981 int interface_number);
983 /* Detach a kernel driver from an interface. Optional.
985 * After detaching a kernel driver, the interface should be available
990 * - LIBUSB_ERROR_NOT_FOUND if no kernel driver was active
991 * - LIBUSB_ERROR_INVALID_PARAM if the interface does not exist
992 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
994 * - another LIBUSB_ERROR code on other failure
996 int (*detach_kernel_driver)(struct libusb_device_handle *dev_handle,
997 int interface_number);
999 /* Attach a kernel driver to an interface. Optional.
1001 * Reattach a kernel driver to the device.
1005 * - LIBUSB_ERROR_NOT_FOUND if no kernel driver was active
1006 * - LIBUSB_ERROR_INVALID_PARAM if the interface does not exist
1007 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
1009 * - LIBUSB_ERROR_BUSY if a program or driver has claimed the interface,
1010 * preventing reattachment
1011 * - another LIBUSB_ERROR code on other failure
1013 int (*attach_kernel_driver)(struct libusb_device_handle *dev_handle,
1014 int interface_number);
1016 /* Destroy a device. Optional.
1018 * This function is called when the last reference to a device is
1019 * destroyed. It should free any resources allocated in the get_device_list
1022 void (*destroy_device)(struct libusb_device *dev);
1024 /* Submit a transfer. Your implementation should take the transfer,
1025 * morph it into whatever form your platform requires, and submit it
1028 * This function must not block.
1030 * This function gets called with the flying_transfers_lock locked!
1034 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
1035 * - another LIBUSB_ERROR code on other failure
1037 int (*submit_transfer)(struct usbi_transfer *itransfer);
1039 /* Cancel a previously submitted transfer.
1041 * This function must not block. The transfer cancellation must complete
1042 * later, resulting in a call to usbi_handle_transfer_cancellation()
1043 * from the context of handle_events.
1045 int (*cancel_transfer)(struct usbi_transfer *itransfer);
1047 /* Clear a transfer as if it has completed or cancelled, but do not
1048 * report any completion/cancellation to the library. You should free
1049 * all private data from the transfer as if you were just about to report
1050 * completion or cancellation.
1052 * This function might seem a bit out of place. It is used when libusb
1053 * detects a disconnected device - it calls this function for all pending
1054 * transfers before reporting completion (with the disconnect code) to
1055 * the user. Maybe we can improve upon this internal interface in future.
1057 void (*clear_transfer_priv)(struct usbi_transfer *itransfer);
1059 /* Handle any pending events on file descriptors. Optional.
1061 * Provide this function when file descriptors directly indicate device
1062 * or transfer activity. If your backend does not have such file descriptors,
1063 * implement the handle_transfer_completion function below.
1065 * This involves monitoring any active transfers and processing their
1066 * completion or cancellation.
1068 * The function is passed an array of pollfd structures (size nfds)
1069 * as a result of the poll() system call. The num_ready parameter
1070 * indicates the number of file descriptors that have reported events
1071 * (i.e. the poll() return value). This should be enough information
1072 * for you to determine which actions need to be taken on the currently
1075 * For any cancelled transfers, call usbi_handle_transfer_cancellation().
1076 * For completed transfers, call usbi_handle_transfer_completion().
1077 * For control/bulk/interrupt transfers, populate the "transferred"
1078 * element of the appropriate usbi_transfer structure before calling the
1079 * above functions. For isochronous transfers, populate the status and
1080 * transferred fields of the iso packet descriptors of the transfer.
1082 * This function should also be able to detect disconnection of the
1083 * device, reporting that situation with usbi_handle_disconnect().
1085 * When processing an event related to a transfer, you probably want to
1086 * take usbi_transfer.lock to prevent races. See the documentation for
1087 * the usbi_transfer structure.
1089 * Return 0 on success, or a LIBUSB_ERROR code on failure.
1091 int (*handle_events)(struct libusb_context *ctx,
1092 struct pollfd *fds, POLL_NFDS_TYPE nfds, int num_ready);
1094 /* Handle transfer completion. Optional.
1096 * Provide this function when there are no file descriptors available
1097 * that directly indicate device or transfer activity. If your backend does
1098 * have such file descriptors, implement the handle_events function above.
1100 * Your backend must tell the library when a transfer has completed by
1101 * calling usbi_signal_transfer_completion(). You should store any private
1102 * information about the transfer and its completion status in the transfer's
1103 * private backend data.
1105 * During event handling, this function will be called on each transfer for
1106 * which usbi_signal_transfer_completion() was called.
1108 * For any cancelled transfers, call usbi_handle_transfer_cancellation().
1109 * For completed transfers, call usbi_handle_transfer_completion().
1110 * For control/bulk/interrupt transfers, populate the "transferred"
1111 * element of the appropriate usbi_transfer structure before calling the
1112 * above functions. For isochronous transfers, populate the status and
1113 * transferred fields of the iso packet descriptors of the transfer.
1115 * Return 0 on success, or a LIBUSB_ERROR code on failure.
1117 int (*handle_transfer_completion)(struct usbi_transfer *itransfer);
1119 /* Get time from specified clock. At least two clocks must be implemented
1120 by the backend: USBI_CLOCK_REALTIME, and USBI_CLOCK_MONOTONIC.
1122 Description of clocks:
1123 USBI_CLOCK_REALTIME : clock returns time since system epoch.
1124 USBI_CLOCK_MONOTONIC: clock returns time since unspecified start
1125 time (usually boot).
1127 int (*clock_gettime)(int clkid, struct timespec *tp);
1129 #ifdef USBI_TIMERFD_AVAILABLE
1130 /* clock ID of the clock that should be used for timerfd */
1131 clockid_t (*get_timerfd_clockid)(void);
1134 /* Number of bytes to reserve for per-context private backend data.
1135 * This private data area is accessible through the "os_priv" field of
1136 * struct libusb_context. */
1137 size_t context_priv_size;
1139 /* Number of bytes to reserve for per-device private backend data.
1140 * This private data area is accessible through the "os_priv" field of
1141 * struct libusb_device. */
1142 size_t device_priv_size;
1144 /* Number of bytes to reserve for per-handle private backend data.
1145 * This private data area is accessible through the "os_priv" field of
1146 * struct libusb_device. */
1147 size_t device_handle_priv_size;
1149 /* Number of bytes to reserve for per-transfer private backend data.
1150 * This private data area is accessible by calling
1151 * usbi_transfer_get_os_priv() on the appropriate usbi_transfer instance.
1153 size_t transfer_priv_size;
1156 extern const struct usbi_os_backend usbi_backend;
1158 extern struct list_head active_contexts_list;
1159 extern usbi_mutex_static_t active_contexts_lock;