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 /* Inside the libusb code, mark all public functions as follows:
43 * return_type API_EXPORTED function_name(params) { ... }
44 * But if the function returns a pointer, mark it as follows:
45 * DEFAULT_VISIBILITY return_type * LIBUSB_CALL function_name(params) { ... }
46 * In the libusb public header, mark all declarations as:
47 * return_type LIBUSB_CALL function_name(params);
49 #define API_EXPORTED LIBUSB_CALL DEFAULT_VISIBILITY
51 #define DEVICE_DESC_LENGTH 18
53 #define USB_MAXENDPOINTS 32
54 #define USB_MAXINTERFACES 32
55 #define USB_MAXCONFIG 8
57 /* Backend specific capabilities */
58 #define USBI_CAP_HAS_HID_ACCESS 0x00010000
59 #define USBI_CAP_SUPPORTS_DETACH_KERNEL_DRIVER 0x00020000
60 #define USBI_CAP_HAS_POLLABLE_DEVICE_FD 0x00040000
62 /* Maximum number of bytes in a log line */
63 #define USBI_MAX_LOG_LEN 1024
64 /* Terminator for log lines */
65 #define USBI_LOG_LINE_END "\n"
67 /* The following is used to silence warnings for unused variables */
68 #define UNUSED(var) do { (void)(var); } while(0)
70 #if !defined(ARRAYSIZE)
71 #define ARRAYSIZE(array) (sizeof(array)/sizeof(array[0]))
75 struct list_head *prev, *next;
78 /* Get an entry from the list
79 * ptr - the address of this list_head element in "type"
80 * type - the data type that contains "member"
81 * member - the list_head element in "type"
83 #define list_entry(ptr, type, member) \
84 ((type *)((uintptr_t)(ptr) - (uintptr_t)offsetof(type, member)))
86 /* Get each entry from a list
87 * pos - A structure pointer has a "member" element
89 * member - the list_head element in "pos"
90 * type - the type of the first parameter
92 #define list_for_each_entry(pos, head, member, type) \
93 for (pos = list_entry((head)->next, type, member); \
94 &pos->member != (head); \
95 pos = list_entry(pos->member.next, type, member))
97 #define list_for_each_entry_safe(pos, n, head, member, type) \
98 for (pos = list_entry((head)->next, type, member), \
99 n = list_entry(pos->member.next, type, member); \
100 &pos->member != (head); \
101 pos = n, n = list_entry(n->member.next, type, member))
103 #define list_empty(entry) ((entry)->next == (entry))
105 static inline void list_init(struct list_head *entry)
107 entry->prev = entry->next = entry;
110 static inline void list_add(struct list_head *entry, struct list_head *head)
112 entry->next = head->next;
115 head->next->prev = entry;
119 static inline void list_add_tail(struct list_head *entry,
120 struct list_head *head)
123 entry->prev = head->prev;
125 head->prev->next = entry;
129 static inline void list_del(struct list_head *entry)
131 entry->next->prev = entry->prev;
132 entry->prev->next = entry->next;
133 entry->next = entry->prev = NULL;
136 static inline void *usbi_reallocf(void *ptr, size_t size)
138 void *ret = realloc(ptr, size);
144 #define container_of(ptr, type, member) ({ \
145 const typeof( ((type *)0)->member ) *mptr = (ptr); \
146 (type *)( (char *)mptr - offsetof(type,member) );})
148 #define MIN(a, b) ((a) < (b) ? (a) : (b))
149 #define MAX(a, b) ((a) > (b) ? (a) : (b))
151 #define TIMESPEC_IS_SET(ts) ((ts)->tv_sec != 0 || (ts)->tv_nsec != 0)
153 /* Some platforms don't have this define */
154 #ifndef TIMESPEC_TO_TIMEVAL
155 #define TIMESPEC_TO_TIMEVAL(tv, ts) \
157 (tv)->tv_sec = (ts)->tv_sec; \
158 (tv)->tv_usec = (ts)->tv_nsec / 1000; \
162 void usbi_log(struct libusb_context *ctx, enum libusb_log_level level,
163 const char *function, const char *format, ...);
165 void usbi_log_v(struct libusb_context *ctx, enum libusb_log_level level,
166 const char *function, const char *format, va_list args);
168 #if !defined(_MSC_VER) || _MSC_VER >= 1400
170 #ifdef ENABLE_LOGGING
171 #define _usbi_log(ctx, level, ...) usbi_log(ctx, level, __FUNCTION__, __VA_ARGS__)
172 #define usbi_dbg(...) _usbi_log(NULL, LIBUSB_LOG_LEVEL_DEBUG, __VA_ARGS__)
174 #define _usbi_log(ctx, level, ...) do { (void)(ctx); } while(0)
175 #define usbi_dbg(...) do {} while(0)
178 #define usbi_info(ctx, ...) _usbi_log(ctx, LIBUSB_LOG_LEVEL_INFO, __VA_ARGS__)
179 #define usbi_warn(ctx, ...) _usbi_log(ctx, LIBUSB_LOG_LEVEL_WARNING, __VA_ARGS__)
180 #define usbi_err(ctx, ...) _usbi_log(ctx, LIBUSB_LOG_LEVEL_ERROR, __VA_ARGS__)
182 #else /* !defined(_MSC_VER) || _MSC_VER >= 1400 */
184 #ifdef ENABLE_LOGGING
185 #define LOG_BODY(ctxt, level) \
188 va_start (args, format); \
189 usbi_log_v(ctxt, level, "", format, args); \
193 #define LOG_BODY(ctxt, level) do { (void)(ctxt); } while(0)
196 static inline void usbi_info(struct libusb_context *ctx, const char *format,
198 LOG_BODY(ctx,LIBUSB_LOG_LEVEL_INFO)
199 static inline void usbi_warn(struct libusb_context *ctx, const char *format,
201 LOG_BODY(ctx,LIBUSB_LOG_LEVEL_WARNING)
202 static inline void usbi_err( struct libusb_context *ctx, const char *format,
204 LOG_BODY(ctx,LIBUSB_LOG_LEVEL_ERROR)
206 static inline void usbi_dbg(const char *format, ...)
207 LOG_BODY(NULL,LIBUSB_LOG_LEVEL_DEBUG)
209 #endif /* !defined(_MSC_VER) || _MSC_VER >= 1400 */
211 #define USBI_GET_CONTEXT(ctx) if (!(ctx)) (ctx) = usbi_default_context
212 #define DEVICE_CTX(dev) ((dev)->ctx)
213 #define HANDLE_CTX(handle) (DEVICE_CTX((handle)->dev))
214 #define TRANSFER_CTX(transfer) (HANDLE_CTX((transfer)->dev_handle))
215 #define ITRANSFER_CTX(transfer) \
216 (TRANSFER_CTX(USBI_TRANSFER_TO_LIBUSB_TRANSFER(transfer)))
218 #define IS_EPIN(ep) (0 != ((ep) & LIBUSB_ENDPOINT_IN))
219 #define IS_EPOUT(ep) (!IS_EPIN(ep))
220 #define IS_XFERIN(xfer) (0 != ((xfer)->endpoint & LIBUSB_ENDPOINT_IN))
221 #define IS_XFEROUT(xfer) (!IS_XFERIN(xfer))
223 /* Internal abstraction for thread synchronization */
224 #if defined(THREADS_POSIX)
225 #include "os/threads_posix.h"
226 #elif defined(OS_WINDOWS) || defined(OS_WINCE)
227 #include <os/threads_windows.h>
230 extern struct libusb_context *usbi_default_context;
232 /* Forward declaration for use in context (fully defined inside poll abstraction) */
235 struct libusb_context {
239 /* internal control pipe, used for interrupting event handling when
240 * something needs to modify poll fds. */
243 struct list_head usb_devs;
244 usbi_mutex_t usb_devs_lock;
246 /* A list of open handles. Backends are free to traverse this if required.
248 struct list_head open_devs;
249 usbi_mutex_t open_devs_lock;
251 /* A list of registered hotplug callbacks */
252 struct list_head hotplug_cbs;
253 usbi_mutex_t hotplug_cbs_lock;
256 /* this is a list of in-flight transfer handles, sorted by timeout
257 * expiration. URBs to timeout the soonest are placed at the beginning of
258 * the list, URBs that will time out later are placed after, and urbs with
259 * infinite timeout are always placed at the very end. */
260 struct list_head flying_transfers;
261 usbi_mutex_t flying_transfers_lock;
263 /* list and count of poll fds and an array of poll fd structures that is
264 * (re)allocated as necessary prior to polling, and a flag to indicate
265 * when the list of poll fds has changed since the last poll. */
266 struct list_head ipollfds;
267 struct pollfd *pollfds;
268 POLL_NFDS_TYPE pollfds_cnt;
269 unsigned int pollfds_modified;
270 usbi_mutex_t pollfds_lock;
272 /* a counter that is set when we want to interrupt event handling, in order
273 * to modify the poll fd set. and a lock to protect it. */
274 unsigned int pollfd_modify;
275 usbi_mutex_t pollfd_modify_lock;
277 /* user callbacks for pollfd changes */
278 libusb_pollfd_added_cb fd_added_cb;
279 libusb_pollfd_removed_cb fd_removed_cb;
280 void *fd_cb_user_data;
282 /* ensures that only one thread is handling events at any one time */
283 usbi_mutex_t events_lock;
285 /* used to see if there is an active thread doing event handling */
286 int event_handler_active;
288 /* used to wait for event completion in threads other than the one that is
290 usbi_mutex_t event_waiters_lock;
291 usbi_cond_t event_waiters_cond;
293 #ifdef USBI_TIMERFD_AVAILABLE
294 /* used for timeout handling, if supported by OS.
295 * this timerfd is maintained to trigger on the next pending timeout */
299 struct list_head list;
302 #ifdef USBI_TIMERFD_AVAILABLE
303 #define usbi_using_timerfd(ctx) ((ctx)->timerfd >= 0)
305 #define usbi_using_timerfd(ctx) (0)
308 struct libusb_device {
309 /* lock protects refcnt, everything else is finalized at initialization
314 struct libusb_context *ctx;
318 struct libusb_device* parent_dev;
319 uint8_t device_address;
320 uint8_t num_configurations;
321 enum libusb_speed speed;
323 struct list_head list;
324 unsigned long session_data;
326 struct libusb_device_descriptor device_descriptor;
329 unsigned char os_priv
330 #if defined(__STDC_VERSION__) && (__STDC_VERSION__ >= 199901L)
331 [] /* valid C99 code */
333 [0] /* non-standard, but usually working code */
338 struct libusb_device_handle {
339 /* lock protects claimed_interfaces */
341 unsigned long claimed_interfaces;
343 struct list_head list;
344 struct libusb_device *dev;
345 int auto_detach_kernel_driver;
346 unsigned char os_priv
347 #if defined(__STDC_VERSION__) && (__STDC_VERSION__ >= 199901L)
348 [] /* valid C99 code */
350 [0] /* non-standard, but usually working code */
356 USBI_CLOCK_MONOTONIC,
360 /* in-memory transfer layout:
362 * 1. struct usbi_transfer
363 * 2. struct libusb_transfer (which includes iso packets) [variable size]
364 * 3. os private data [variable size]
366 * from a libusb_transfer, you can get the usbi_transfer by rewinding the
367 * appropriate number of bytes.
368 * the usbi_transfer includes the number of allocated packets, so you can
369 * determine the size of the transfer and hence the start and length of the
373 struct usbi_transfer {
375 struct list_head list;
376 struct timeval timeout;
381 /* this lock is held during libusb_submit_transfer() and
382 * libusb_cancel_transfer() (allowing the OS backend to prevent duplicate
383 * cancellation, submission-during-cancellation, etc). the OS backend
384 * should also take this lock in the handle_events path, to prevent the user
385 * cancelling the transfer from another thread while you are processing
386 * its completion (presumably there would be races within your OS backend
387 * if this were possible). */
391 enum usbi_transfer_flags {
392 /* The transfer has timed out */
393 USBI_TRANSFER_TIMED_OUT = 1 << 0,
395 /* Set by backend submit_transfer() if the OS handles timeout */
396 USBI_TRANSFER_OS_HANDLES_TIMEOUT = 1 << 1,
398 /* Cancellation was requested via libusb_cancel_transfer() */
399 USBI_TRANSFER_CANCELLING = 1 << 2,
401 /* Operation on the transfer failed because the device disappeared */
402 USBI_TRANSFER_DEVICE_DISAPPEARED = 1 << 3,
404 /* Set by backend submit_transfer() if the fds in use have been updated */
405 USBI_TRANSFER_UPDATED_FDS = 1 << 4,
408 #define USBI_TRANSFER_TO_LIBUSB_TRANSFER(transfer) \
409 ((struct libusb_transfer *)(((unsigned char *)(transfer)) \
410 + sizeof(struct usbi_transfer)))
411 #define LIBUSB_TRANSFER_TO_USBI_TRANSFER(transfer) \
412 ((struct usbi_transfer *)(((unsigned char *)(transfer)) \
413 - sizeof(struct usbi_transfer)))
415 static inline void *usbi_transfer_get_os_priv(struct usbi_transfer *transfer)
417 return ((unsigned char *)transfer) + sizeof(struct usbi_transfer)
418 + sizeof(struct libusb_transfer)
419 + (transfer->num_iso_packets
420 * sizeof(struct libusb_iso_packet_descriptor));
425 /* All standard descriptors have these 2 fields in common */
426 struct usb_descriptor_header {
428 uint8_t bDescriptorType;
431 /* shared data and functions */
433 int usbi_io_init(struct libusb_context *ctx);
434 void usbi_io_exit(struct libusb_context *ctx);
436 struct libusb_device *usbi_alloc_device(struct libusb_context *ctx,
437 unsigned long session_id);
438 struct libusb_device *usbi_get_device_by_session_id(struct libusb_context *ctx,
439 unsigned long session_id);
440 int usbi_sanitize_device(struct libusb_device *dev);
441 void usbi_handle_disconnect(struct libusb_device_handle *handle);
443 int usbi_handle_transfer_completion(struct usbi_transfer *itransfer,
444 enum libusb_transfer_status status);
445 int usbi_handle_transfer_cancellation(struct usbi_transfer *transfer);
447 int usbi_parse_descriptor(const unsigned char *source, const char *descriptor,
448 void *dest, int host_endian);
449 int usbi_device_cache_descriptor(libusb_device *dev);
450 int usbi_get_config_index_by_value(struct libusb_device *dev,
451 uint8_t bConfigurationValue, int *idx);
453 void usbi_connect_device (struct libusb_device *dev);
454 void usbi_disconnect_device (struct libusb_device *dev);
456 /* Internal abstraction for poll (needs struct usbi_transfer on Windows) */
457 #if defined(OS_LINUX) || defined(OS_DARWIN) || defined(OS_OPENBSD) || defined(OS_NETBSD)
459 #include "os/poll_posix.h"
460 #elif defined(OS_WINDOWS) || defined(OS_WINCE)
461 #include "os/poll_windows.h"
464 #if (defined(OS_WINDOWS) || defined(OS_WINCE)) && !defined(__GNUC__)
465 #define snprintf _snprintf
466 #define vsnprintf _vsnprintf
467 int usbi_gettimeofday(struct timeval *tp, void *tzp);
468 #define LIBUSB_GETTIMEOFDAY_WIN32
469 #define HAVE_USBI_GETTIMEOFDAY
471 #ifdef HAVE_GETTIMEOFDAY
472 #define usbi_gettimeofday(tv, tz) gettimeofday((tv), (tz))
473 #define HAVE_USBI_GETTIMEOFDAY
478 /* must come first */
479 struct libusb_pollfd pollfd;
481 struct list_head list;
484 int usbi_add_pollfd(struct libusb_context *ctx, int fd, short events);
485 void usbi_remove_pollfd(struct libusb_context *ctx, int fd);
486 void usbi_fd_notification(struct libusb_context *ctx);
488 /* device discovery */
490 /* we traverse usbfs without knowing how many devices we are going to find.
491 * so we create this discovered_devs model which is similar to a linked-list
492 * which grows when required. it can be freed once discovery has completed,
493 * eliminating the need for a list node in the libusb_device structure
495 struct discovered_devs {
498 struct libusb_device *devices
499 #if defined(__STDC_VERSION__) && (__STDC_VERSION__ >= 199901L)
500 [] /* valid C99 code */
502 [0] /* non-standard, but usually working code */
507 struct discovered_devs *discovered_devs_append(
508 struct discovered_devs *discdevs, struct libusb_device *dev);
512 /* This is the interface that OS backends need to implement.
513 * All fields are mandatory, except ones explicitly noted as optional. */
514 struct usbi_os_backend {
515 /* A human-readable name for your backend, e.g. "Linux usbfs" */
518 /* Binary mask for backend specific capabilities */
521 /* Perform initialization of your backend. You might use this function
522 * to determine specific capabilities of the system, allocate required
523 * data structures for later, etc.
525 * This function is called when a libusb user initializes the library
528 * Return 0 on success, or a LIBUSB_ERROR code on failure.
530 int (*init)(struct libusb_context *ctx);
532 /* Deinitialization. Optional. This function should destroy anything
533 * that was set up by init.
535 * This function is called when the user deinitializes the library.
539 /* Enumerate all the USB devices on the system, returning them in a list
540 * of discovered devices.
542 * Your implementation should enumerate all devices on the system,
543 * regardless of whether they have been seen before or not.
545 * When you have found a device, compute a session ID for it. The session
546 * ID should uniquely represent that particular device for that particular
547 * connection session since boot (i.e. if you disconnect and reconnect a
548 * device immediately after, it should be assigned a different session ID).
549 * If your OS cannot provide a unique session ID as described above,
550 * presenting a session ID of (bus_number << 8 | device_address) should
551 * be sufficient. Bus numbers and device addresses wrap and get reused,
552 * but that is an unlikely case.
554 * After computing a session ID for a device, call
555 * usbi_get_device_by_session_id(). This function checks if libusb already
556 * knows about the device, and if so, it provides you with a reference
557 * to a libusb_device structure for it.
559 * If usbi_get_device_by_session_id() returns NULL, it is time to allocate
560 * a new device structure for the device. Call usbi_alloc_device() to
561 * obtain a new libusb_device structure with reference count 1. Populate
562 * the bus_number and device_address attributes of the new device, and
563 * perform any other internal backend initialization you need to do. At
564 * this point, you should be ready to provide device descriptors and so
565 * on through the get_*_descriptor functions. Finally, call
566 * usbi_sanitize_device() to perform some final sanity checks on the
567 * device. Assuming all of the above succeeded, we can now continue.
568 * If any of the above failed, remember to unreference the device that
569 * was returned by usbi_alloc_device().
571 * At this stage we have a populated libusb_device structure (either one
572 * that was found earlier, or one that we have just allocated and
573 * populated). This can now be added to the discovered devices list
574 * using discovered_devs_append(). Note that discovered_devs_append()
575 * may reallocate the list, returning a new location for it, and also
576 * note that reallocation can fail. Your backend should handle these
577 * error conditions appropriately.
579 * This function should not generate any bus I/O and should not block.
580 * If I/O is required (e.g. reading the active configuration value), it is
581 * OK to ignore these suggestions :)
583 * This function is executed when the user wishes to retrieve a list
584 * of USB devices connected to the system.
586 * If the backend has hotplug support, this function is not used!
588 * Return 0 on success, or a LIBUSB_ERROR code on failure.
590 int (*get_device_list)(struct libusb_context *ctx,
591 struct discovered_devs **discdevs);
593 /* Apps which were written before hotplug support, may listen for
594 * hotplug events on their own and call libusb_get_device_list on
595 * device addition. In this case libusb_get_device_list will likely
596 * return a list without the new device in there, as the hotplug
597 * event thread will still be busy enumerating the device, which may
598 * take a while, or may not even have seen the event yet.
600 * To avoid this libusb_get_device_list will call this optional
601 * function for backends with hotplug support before copying
602 * ctx->usb_devs to the user. In this function the backend should
603 * ensure any pending hotplug events are fully processed before
606 * Optional, should be implemented by backends with hotplug support.
608 void (*hotplug_poll)(void);
610 /* Open a device for I/O and other USB operations. The device handle
611 * is preallocated for you, you can retrieve the device in question
612 * through handle->dev.
614 * Your backend should allocate any internal resources required for I/O
615 * and other operations so that those operations can happen (hopefully)
616 * without hiccup. This is also a good place to inform libusb that it
617 * should monitor certain file descriptors related to this device -
618 * see the usbi_add_pollfd() function.
620 * This function should not generate any bus I/O and should not block.
622 * This function is called when the user attempts to obtain a device
623 * handle for a device.
627 * - LIBUSB_ERROR_ACCESS if the user has insufficient permissions
628 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since
630 * - another LIBUSB_ERROR code on other failure
632 * Do not worry about freeing the handle on failed open, the upper layers
635 int (*open)(struct libusb_device_handle *handle);
637 /* Close a device such that the handle cannot be used again. Your backend
638 * should destroy any resources that were allocated in the open path.
639 * This may also be a good place to call usbi_remove_pollfd() to inform
640 * libusb of any file descriptors associated with this device that should
641 * no longer be monitored.
643 * This function is called when the user closes a device handle.
645 void (*close)(struct libusb_device_handle *handle);
647 /* Retrieve the device descriptor from a device.
649 * The descriptor should be retrieved from memory, NOT via bus I/O to the
650 * device. This means that you may have to cache it in a private structure
651 * during get_device_list enumeration. Alternatively, you may be able
652 * to retrieve it from a kernel interface (some Linux setups can do this)
653 * still without generating bus I/O.
655 * This function is expected to write DEVICE_DESC_LENGTH (18) bytes into
656 * buffer, which is guaranteed to be big enough.
658 * This function is called when sanity-checking a device before adding
659 * it to the list of discovered devices, and also when the user requests
660 * to read the device descriptor.
662 * This function is expected to return the descriptor in bus-endian format
663 * (LE). If it returns the multi-byte values in host-endian format,
664 * set the host_endian output parameter to "1".
666 * Return 0 on success or a LIBUSB_ERROR code on failure.
668 int (*get_device_descriptor)(struct libusb_device *device,
669 unsigned char *buffer, int *host_endian);
671 /* Get the ACTIVE configuration descriptor for a device.
673 * The descriptor should be retrieved from memory, NOT via bus I/O to the
674 * device. This means that you may have to cache it in a private structure
675 * during get_device_list enumeration. You may also have to keep track
676 * of which configuration is active when the user changes it.
678 * This function is expected to write len bytes of data into buffer, which
679 * is guaranteed to be big enough. If you can only do a partial write,
680 * return an error code.
682 * This function is expected to return the descriptor in bus-endian format
683 * (LE). If it returns the multi-byte values in host-endian format,
684 * set the host_endian output parameter to "1".
688 * - LIBUSB_ERROR_NOT_FOUND if the device is in unconfigured state
689 * - another LIBUSB_ERROR code on other failure
691 int (*get_active_config_descriptor)(struct libusb_device *device,
692 unsigned char *buffer, size_t len, int *host_endian);
694 /* Get a specific configuration descriptor for a device.
696 * The descriptor should be retrieved from memory, NOT via bus I/O to the
697 * device. This means that you may have to cache it in a private structure
698 * during get_device_list enumeration.
700 * The requested descriptor is expressed as a zero-based index (i.e. 0
701 * indicates that we are requesting the first descriptor). The index does
702 * not (necessarily) equal the bConfigurationValue of the configuration
705 * This function is expected to write len bytes of data into buffer, which
706 * is guaranteed to be big enough. If you can only do a partial write,
707 * return an error code.
709 * This function is expected to return the descriptor in bus-endian format
710 * (LE). If it returns the multi-byte values in host-endian format,
711 * set the host_endian output parameter to "1".
713 * Return the length read on success or a LIBUSB_ERROR code on failure.
715 int (*get_config_descriptor)(struct libusb_device *device,
716 uint8_t config_index, unsigned char *buffer, size_t len,
719 /* Like get_config_descriptor but then by bConfigurationValue instead
722 * Optional, if not present the core will call get_config_descriptor
723 * for all configs until it finds the desired bConfigurationValue.
725 * Returns a pointer to the raw-descriptor in *buffer, this memory
726 * is valid as long as device is valid.
728 * Returns the length of the returned raw-descriptor on success,
729 * or a LIBUSB_ERROR code on failure.
731 int (*get_config_descriptor_by_value)(struct libusb_device *device,
732 uint8_t bConfigurationValue, unsigned char **buffer,
735 /* Get the bConfigurationValue for the active configuration for a device.
736 * Optional. This should only be implemented if you can retrieve it from
737 * cache (don't generate I/O).
739 * If you cannot retrieve this from cache, either do not implement this
740 * function, or return LIBUSB_ERROR_NOT_SUPPORTED. This will cause
741 * libusb to retrieve the information through a standard control transfer.
743 * This function must be non-blocking.
746 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
748 * - LIBUSB_ERROR_NOT_SUPPORTED if the value cannot be retrieved without
750 * - another LIBUSB_ERROR code on other failure.
752 int (*get_configuration)(struct libusb_device_handle *handle, int *config);
754 /* Set the active configuration for a device.
756 * A configuration value of -1 should put the device in unconfigured state.
758 * This function can block.
762 * - LIBUSB_ERROR_NOT_FOUND if the configuration does not exist
763 * - LIBUSB_ERROR_BUSY if interfaces are currently claimed (and hence
764 * configuration cannot be changed)
765 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
767 * - another LIBUSB_ERROR code on other failure.
769 int (*set_configuration)(struct libusb_device_handle *handle, int config);
771 /* Claim an interface. When claimed, the application can then perform
772 * I/O to an interface's endpoints.
774 * This function should not generate any bus I/O and should not block.
775 * Interface claiming is a logical operation that simply ensures that
776 * no other drivers/applications are using the interface, and after
777 * claiming, no other drivers/applicatiosn can use the interface because
782 * - LIBUSB_ERROR_NOT_FOUND if the interface does not exist
783 * - LIBUSB_ERROR_BUSY if the interface is in use by another driver/app
784 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
786 * - another LIBUSB_ERROR code on other failure
788 int (*claim_interface)(struct libusb_device_handle *handle, int interface_number);
790 /* Release a previously claimed interface.
792 * This function should also generate a SET_INTERFACE control request,
793 * resetting the alternate setting of that interface to 0. It's OK for
794 * this function to block as a result.
796 * You will only ever be asked to release an interface which was
797 * successfully claimed earlier.
801 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
803 * - another LIBUSB_ERROR code on other failure
805 int (*release_interface)(struct libusb_device_handle *handle, int interface_number);
807 /* Set the alternate setting for an interface.
809 * You will only ever be asked to set the alternate setting for an
810 * interface which was successfully claimed earlier.
812 * It's OK for this function to block.
816 * - LIBUSB_ERROR_NOT_FOUND if the alternate setting does not exist
817 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
819 * - another LIBUSB_ERROR code on other failure
821 int (*set_interface_altsetting)(struct libusb_device_handle *handle,
822 int interface_number, int altsetting);
824 /* Clear a halt/stall condition on an endpoint.
826 * It's OK for this function to block.
830 * - LIBUSB_ERROR_NOT_FOUND if the endpoint does not exist
831 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
833 * - another LIBUSB_ERROR code on other failure
835 int (*clear_halt)(struct libusb_device_handle *handle,
836 unsigned char endpoint);
838 /* Perform a USB port reset to reinitialize a device.
840 * If possible, the handle should still be usable after the reset
841 * completes, assuming that the device descriptors did not change during
842 * reset and all previous interface state can be restored.
844 * If something changes, or you cannot easily locate/verify the resetted
845 * device, return LIBUSB_ERROR_NOT_FOUND. This prompts the application
846 * to close the old handle and re-enumerate the device.
850 * - LIBUSB_ERROR_NOT_FOUND if re-enumeration is required, or if the device
851 * has been disconnected since it was opened
852 * - another LIBUSB_ERROR code on other failure
854 int (*reset_device)(struct libusb_device_handle *handle);
856 /* Alloc num_streams usb3 bulk streams on the passed in endpoints */
857 int (*alloc_streams)(struct libusb_device_handle *handle,
858 uint32_t num_streams, unsigned char *endpoints, int num_endpoints);
860 /* Free usb3 bulk streams allocated with alloc_streams */
861 int (*free_streams)(struct libusb_device_handle *handle,
862 unsigned char *endpoints, int num_endpoints);
864 /* Determine if a kernel driver is active on an interface. Optional.
866 * The presence of a kernel driver on an interface indicates that any
867 * calls to claim_interface would fail with the LIBUSB_ERROR_BUSY code.
870 * - 0 if no driver is active
871 * - 1 if a driver is active
872 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
874 * - another LIBUSB_ERROR code on other failure
876 int (*kernel_driver_active)(struct libusb_device_handle *handle,
877 int interface_number);
879 /* Detach a kernel driver from an interface. Optional.
881 * After detaching a kernel driver, the interface should be available
886 * - LIBUSB_ERROR_NOT_FOUND if no kernel driver was active
887 * - LIBUSB_ERROR_INVALID_PARAM if the interface does not exist
888 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
890 * - another LIBUSB_ERROR code on other failure
892 int (*detach_kernel_driver)(struct libusb_device_handle *handle,
893 int interface_number);
895 /* Attach a kernel driver to an interface. Optional.
897 * Reattach a kernel driver to the device.
901 * - LIBUSB_ERROR_NOT_FOUND if no kernel driver was active
902 * - LIBUSB_ERROR_INVALID_PARAM if the interface does not exist
903 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
905 * - LIBUSB_ERROR_BUSY if a program or driver has claimed the interface,
906 * preventing reattachment
907 * - another LIBUSB_ERROR code on other failure
909 int (*attach_kernel_driver)(struct libusb_device_handle *handle,
910 int interface_number);
912 /* Destroy a device. Optional.
914 * This function is called when the last reference to a device is
915 * destroyed. It should free any resources allocated in the get_device_list
918 void (*destroy_device)(struct libusb_device *dev);
920 /* Submit a transfer. Your implementation should take the transfer,
921 * morph it into whatever form your platform requires, and submit it
924 * This function must not block.
926 * This function gets called with the flying_transfers_lock locked!
930 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
931 * - another LIBUSB_ERROR code on other failure
933 int (*submit_transfer)(struct usbi_transfer *itransfer);
935 /* Cancel a previously submitted transfer.
937 * This function must not block. The transfer cancellation must complete
938 * later, resulting in a call to usbi_handle_transfer_cancellation()
939 * from the context of handle_events.
941 int (*cancel_transfer)(struct usbi_transfer *itransfer);
943 /* Clear a transfer as if it has completed or cancelled, but do not
944 * report any completion/cancellation to the library. You should free
945 * all private data from the transfer as if you were just about to report
946 * completion or cancellation.
948 * This function might seem a bit out of place. It is used when libusb
949 * detects a disconnected device - it calls this function for all pending
950 * transfers before reporting completion (with the disconnect code) to
951 * the user. Maybe we can improve upon this internal interface in future.
953 void (*clear_transfer_priv)(struct usbi_transfer *itransfer);
955 /* Handle any pending events. This involves monitoring any active
956 * transfers and processing their completion or cancellation.
958 * The function is passed an array of pollfd structures (size nfds)
959 * as a result of the poll() system call. The num_ready parameter
960 * indicates the number of file descriptors that have reported events
961 * (i.e. the poll() return value). This should be enough information
962 * for you to determine which actions need to be taken on the currently
965 * For any cancelled transfers, call usbi_handle_transfer_cancellation().
966 * For completed transfers, call usbi_handle_transfer_completion().
967 * For control/bulk/interrupt transfers, populate the "transferred"
968 * element of the appropriate usbi_transfer structure before calling the
969 * above functions. For isochronous transfers, populate the status and
970 * transferred fields of the iso packet descriptors of the transfer.
972 * This function should also be able to detect disconnection of the
973 * device, reporting that situation with usbi_handle_disconnect().
975 * When processing an event related to a transfer, you probably want to
976 * take usbi_transfer.lock to prevent races. See the documentation for
977 * the usbi_transfer structure.
979 * Return 0 on success, or a LIBUSB_ERROR code on failure.
981 int (*handle_events)(struct libusb_context *ctx,
982 struct pollfd *fds, POLL_NFDS_TYPE nfds, int num_ready);
984 /* Get time from specified clock. At least two clocks must be implemented
985 by the backend: USBI_CLOCK_REALTIME, and USBI_CLOCK_MONOTONIC.
987 Description of clocks:
988 USBI_CLOCK_REALTIME : clock returns time since system epoch.
989 USBI_CLOCK_MONOTONIC: clock returns time since unspecified start
992 int (*clock_gettime)(int clkid, struct timespec *tp);
994 #ifdef USBI_TIMERFD_AVAILABLE
995 /* clock ID of the clock that should be used for timerfd */
996 clockid_t (*get_timerfd_clockid)(void);
999 /* Number of bytes to reserve for per-device private backend data.
1000 * This private data area is accessible through the "os_priv" field of
1001 * struct libusb_device. */
1002 size_t device_priv_size;
1004 /* Number of bytes to reserve for per-handle private backend data.
1005 * This private data area is accessible through the "os_priv" field of
1006 * struct libusb_device. */
1007 size_t device_handle_priv_size;
1009 /* Number of bytes to reserve for per-transfer private backend data.
1010 * This private data area is accessible by calling
1011 * usbi_transfer_get_os_priv() on the appropriate usbi_transfer instance.
1013 size_t transfer_priv_size;
1015 /* Mumber of additional bytes for os_priv for each iso packet.
1016 * Can your backend use this? */
1017 /* FIXME: linux can't use this any more. if other OS's cannot either,
1018 * then remove this */
1019 size_t add_iso_packet_size;
1022 extern const struct usbi_os_backend * const usbi_backend;
1024 extern const struct usbi_os_backend linux_usbfs_backend;
1025 extern const struct usbi_os_backend darwin_backend;
1026 extern const struct usbi_os_backend openbsd_backend;
1027 extern const struct usbi_os_backend netbsd_backend;
1028 extern const struct usbi_os_backend windows_backend;
1029 extern const struct usbi_os_backend wince_backend;
1031 extern struct list_head active_contexts_list;
1032 extern usbi_mutex_static_t active_contexts_lock;