1 #include <linux/module.h>
2 #include <linux/string.h>
3 #include <linux/bitops.h>
4 #include <linux/slab.h>
5 #include <linux/init.h>
7 #include <linux/wait.h>
10 #define to_urb(d) container_of(d, struct urb, kref)
12 static void urb_destroy(struct kref *kref)
14 struct urb *urb = to_urb(kref);
20 * usb_init_urb - initializes a urb so that it can be used by a USB driver
21 * @urb: pointer to the urb to initialize
23 * Initializes a urb so that the USB subsystem can use it properly.
25 * If a urb is created with a call to usb_alloc_urb() it is not
26 * necessary to call this function. Only use this if you allocate the
27 * space for a struct urb on your own. If you call this function, be
28 * careful when freeing the memory for your urb that it is no longer in
29 * use by the USB core.
31 * Only use this function if you _really_ understand what you are doing.
33 void usb_init_urb(struct urb *urb)
36 memset(urb, 0, sizeof(*urb));
37 kref_init(&urb->kref);
38 spin_lock_init(&urb->lock);
39 INIT_LIST_HEAD(&urb->anchor_list);
44 * usb_alloc_urb - creates a new urb for a USB driver to use
45 * @iso_packets: number of iso packets for this urb
46 * @mem_flags: the type of memory to allocate, see kmalloc() for a list of
47 * valid options for this.
49 * Creates an urb for the USB driver to use, initializes a few internal
50 * structures, incrementes the usage counter, and returns a pointer to it.
52 * If no memory is available, NULL is returned.
54 * If the driver want to use this urb for interrupt, control, or bulk
55 * endpoints, pass '0' as the number of iso packets.
57 * The driver must call usb_free_urb() when it is finished with the urb.
59 struct urb *usb_alloc_urb(int iso_packets, gfp_t mem_flags)
63 urb = kmalloc(sizeof(struct urb) +
64 iso_packets * sizeof(struct usb_iso_packet_descriptor),
67 err("alloc_urb: kmalloc failed");
75 * usb_free_urb - frees the memory used by a urb when all users of it are finished
76 * @urb: pointer to the urb to free, may be NULL
78 * Must be called when a user of a urb is finished with it. When the last user
79 * of the urb calls this function, the memory of the urb is freed.
81 * Note: The transfer buffer associated with the urb is not freed, that must be
84 void usb_free_urb(struct urb *urb)
87 kref_put(&urb->kref, urb_destroy);
91 * usb_get_urb - increments the reference count of the urb
92 * @urb: pointer to the urb to modify, may be NULL
94 * This must be called whenever a urb is transferred from a device driver to a
95 * host controller driver. This allows proper reference counting to happen
98 * A pointer to the urb with the incremented reference counter is returned.
100 struct urb * usb_get_urb(struct urb *urb)
103 kref_get(&urb->kref);
108 * usb_anchor_urb - anchors an URB while it is processed
109 * @urb: pointer to the urb to anchor
110 * @anchor: pointer to the anchor
112 * This can be called to have access to URBs which are to be executed
113 * without bothering to track them
115 void usb_anchor_urb(struct urb *urb, struct usb_anchor *anchor)
119 spin_lock_irqsave(&anchor->lock, flags);
121 list_add_tail(&urb->anchor_list, &anchor->urb_list);
122 urb->anchor = anchor;
123 spin_unlock_irqrestore(&anchor->lock, flags);
125 EXPORT_SYMBOL_GPL(usb_anchor_urb);
128 * usb_unanchor_urb - unanchors an URB
129 * @urb: pointer to the urb to anchor
131 * Call this to stop the system keeping track of this URB
133 void usb_unanchor_urb(struct urb *urb)
136 struct usb_anchor *anchor;
141 anchor = urb->anchor;
145 spin_lock_irqsave(&anchor->lock, flags);
146 if (unlikely(anchor != urb->anchor)) {
147 /* we've lost the race to another thread */
148 spin_unlock_irqrestore(&anchor->lock, flags);
152 list_del(&urb->anchor_list);
153 spin_unlock_irqrestore(&anchor->lock, flags);
155 if (list_empty(&anchor->urb_list))
156 wake_up(&anchor->wait);
158 EXPORT_SYMBOL_GPL(usb_unanchor_urb);
160 /*-------------------------------------------------------------------*/
163 * usb_submit_urb - issue an asynchronous transfer request for an endpoint
164 * @urb: pointer to the urb describing the request
165 * @mem_flags: the type of memory to allocate, see kmalloc() for a list
166 * of valid options for this.
168 * This submits a transfer request, and transfers control of the URB
169 * describing that request to the USB subsystem. Request completion will
170 * be indicated later, asynchronously, by calling the completion handler.
171 * The three types of completion are success, error, and unlink
172 * (a software-induced fault, also called "request cancellation").
174 * URBs may be submitted in interrupt context.
176 * The caller must have correctly initialized the URB before submitting
177 * it. Functions such as usb_fill_bulk_urb() and usb_fill_control_urb() are
178 * available to ensure that most fields are correctly initialized, for
179 * the particular kind of transfer, although they will not initialize
180 * any transfer flags.
182 * Successful submissions return 0; otherwise this routine returns a
183 * negative error number. If the submission is successful, the complete()
184 * callback from the URB will be called exactly once, when the USB core and
185 * Host Controller Driver (HCD) are finished with the URB. When the completion
186 * function is called, control of the URB is returned to the device
187 * driver which issued the request. The completion handler may then
188 * immediately free or reuse that URB.
190 * With few exceptions, USB device drivers should never access URB fields
191 * provided by usbcore or the HCD until its complete() is called.
192 * The exceptions relate to periodic transfer scheduling. For both
193 * interrupt and isochronous urbs, as part of successful URB submission
194 * urb->interval is modified to reflect the actual transfer period used
195 * (normally some power of two units). And for isochronous urbs,
196 * urb->start_frame is modified to reflect when the URB's transfers were
197 * scheduled to start. Not all isochronous transfer scheduling policies
198 * will work, but most host controller drivers should easily handle ISO
199 * queues going from now until 10-200 msec into the future.
201 * For control endpoints, the synchronous usb_control_msg() call is
202 * often used (in non-interrupt context) instead of this call.
203 * That is often used through convenience wrappers, for the requests
204 * that are standardized in the USB 2.0 specification. For bulk
205 * endpoints, a synchronous usb_bulk_msg() call is available.
209 * URBs may be submitted to endpoints before previous ones complete, to
210 * minimize the impact of interrupt latencies and system overhead on data
211 * throughput. With that queuing policy, an endpoint's queue would never
212 * be empty. This is required for continuous isochronous data streams,
213 * and may also be required for some kinds of interrupt transfers. Such
214 * queuing also maximizes bandwidth utilization by letting USB controllers
215 * start work on later requests before driver software has finished the
216 * completion processing for earlier (successful) requests.
218 * As of Linux 2.6, all USB endpoint transfer queues support depths greater
219 * than one. This was previously a HCD-specific behavior, except for ISO
220 * transfers. Non-isochronous endpoint queues are inactive during cleanup
221 * after faults (transfer errors or cancellation).
223 * Reserved Bandwidth Transfers:
225 * Periodic transfers (interrupt or isochronous) are performed repeatedly,
226 * using the interval specified in the urb. Submitting the first urb to
227 * the endpoint reserves the bandwidth necessary to make those transfers.
228 * If the USB subsystem can't allocate sufficient bandwidth to perform
229 * the periodic request, submitting such a periodic request should fail.
231 * Device drivers must explicitly request that repetition, by ensuring that
232 * some URB is always on the endpoint's queue (except possibly for short
233 * periods during completion callacks). When there is no longer an urb
234 * queued, the endpoint's bandwidth reservation is canceled. This means
235 * drivers can use their completion handlers to ensure they keep bandwidth
236 * they need, by reinitializing and resubmitting the just-completed urb
237 * until the driver longer needs that periodic bandwidth.
241 * The general rules for how to decide which mem_flags to use
242 * are the same as for kmalloc. There are four
243 * different possible values; GFP_KERNEL, GFP_NOFS, GFP_NOIO and
246 * GFP_NOFS is not ever used, as it has not been implemented yet.
248 * GFP_ATOMIC is used when
249 * (a) you are inside a completion handler, an interrupt, bottom half,
250 * tasklet or timer, or
251 * (b) you are holding a spinlock or rwlock (does not apply to
253 * (c) current->state != TASK_RUNNING, this is the case only after
256 * GFP_NOIO is used in the block io path and error handling of storage
259 * All other situations use GFP_KERNEL.
261 * Some more specific rules for mem_flags can be inferred, such as
262 * (1) start_xmit, timeout, and receive methods of network drivers must
263 * use GFP_ATOMIC (they are called with a spinlock held);
264 * (2) queuecommand methods of scsi drivers must use GFP_ATOMIC (also
265 * called with a spinlock held);
266 * (3) If you use a kernel thread with a network driver you must use
267 * GFP_NOIO, unless (b) or (c) apply;
268 * (4) after you have done a down() you can use GFP_KERNEL, unless (b) or (c)
269 * apply or your are in a storage driver's block io path;
270 * (5) USB probe and disconnect can use GFP_KERNEL unless (b) or (c) apply; and
271 * (6) changing firmware on a running storage or net device uses
272 * GFP_NOIO, unless b) or c) apply
275 int usb_submit_urb(struct urb *urb, gfp_t mem_flags)
278 struct usb_device *dev;
281 if (!urb || urb->hcpriv || !urb->complete)
283 if (!(dev = urb->dev) ||
284 (dev->state < USB_STATE_DEFAULT) ||
285 (!dev->bus) || (dev->devnum <= 0))
287 if (dev->bus->controller->power.power_state.event != PM_EVENT_ON
288 || dev->state == USB_STATE_SUSPENDED)
289 return -EHOSTUNREACH;
291 urb->status = -EINPROGRESS;
292 urb->actual_length = 0;
294 /* Lots of sanity checks, so HCDs can rely on clean data
295 * and don't need to duplicate tests
298 temp = usb_pipetype(pipe);
299 is_out = usb_pipeout(pipe);
301 if (!usb_pipecontrol(pipe) && dev->state < USB_STATE_CONFIGURED)
304 /* FIXME there should be a sharable lock protecting us against
305 * config/altsetting changes and disconnects, kicking in here.
306 * (here == before maxpacket, and eventually endpoint type,
310 max = usb_maxpacket(dev, pipe, is_out);
313 "bogus endpoint ep%d%s in %s (bad maxpacket %d)\n",
314 usb_pipeendpoint(pipe), is_out ? "out" : "in",
319 /* periodic transfers limit size per frame/uframe,
320 * but drivers only control those sizes for ISO.
321 * while we're checking, initialize return status.
323 if (temp == PIPE_ISOCHRONOUS) {
326 /* "high bandwidth" mode, 1-3 packets/uframe? */
327 if (dev->speed == USB_SPEED_HIGH) {
328 int mult = 1 + ((max >> 11) & 0x03);
333 if (urb->number_of_packets <= 0)
335 for (n = 0; n < urb->number_of_packets; n++) {
336 len = urb->iso_frame_desc[n].length;
337 if (len < 0 || len > max)
339 urb->iso_frame_desc[n].status = -EXDEV;
340 urb->iso_frame_desc[n].actual_length = 0;
344 /* the I/O buffer must be mapped/unmapped, except when length=0 */
345 if (urb->transfer_buffer_length < 0)
349 /* stuff that drivers shouldn't do, but which shouldn't
350 * cause problems in HCDs if they get it wrong.
353 unsigned int orig_flags = urb->transfer_flags;
354 unsigned int allowed;
356 /* enforce simple/standard policy */
357 allowed = (URB_NO_TRANSFER_DMA_MAP | URB_NO_SETUP_DMA_MAP |
362 allowed |= URB_ZERO_PACKET;
365 allowed |= URB_NO_FSBR; /* only affects UHCI */
367 default: /* all non-iso endpoints */
369 allowed |= URB_SHORT_NOT_OK;
371 case PIPE_ISOCHRONOUS:
372 allowed |= URB_ISO_ASAP;
375 urb->transfer_flags &= allowed;
377 /* fail if submitter gave bogus flags */
378 if (urb->transfer_flags != orig_flags) {
379 err("BOGUS urb flags, %x --> %x",
380 orig_flags, urb->transfer_flags);
386 * Force periodic transfer intervals to be legal values that are
387 * a power of two (so HCDs don't need to).
389 * FIXME want bus->{intr,iso}_sched_horizon values here. Each HC
390 * supports different values... this uses EHCI/UHCI defaults (and
391 * EHCI can use smaller non-default values).
394 case PIPE_ISOCHRONOUS:
397 if (urb->interval <= 0)
400 switch (dev->speed) {
401 case USB_SPEED_HIGH: /* units are microframes */
402 // NOTE usb handles 2^15
403 if (urb->interval > (1024 * 8))
404 urb->interval = 1024 * 8;
407 case USB_SPEED_FULL: /* units are frames/msec */
409 if (temp == PIPE_INTERRUPT) {
410 if (urb->interval > 255)
412 // NOTE ohci only handles up to 32
415 if (urb->interval > 1024)
416 urb->interval = 1024;
417 // NOTE usb and ohci handle up to 2^15
425 while (temp > urb->interval)
427 urb->interval = temp;
430 return usb_hcd_submit_urb(urb, mem_flags);
433 /*-------------------------------------------------------------------*/
436 * usb_unlink_urb - abort/cancel a transfer request for an endpoint
437 * @urb: pointer to urb describing a previously submitted request,
440 * This routine cancels an in-progress request. URBs complete only
441 * once per submission, and may be canceled only once per submission.
442 * Successful cancellation means the requests's completion handler will
443 * be called with a status code indicating that the request has been
444 * canceled (rather than any other code) and will quickly be removed
445 * from host controller data structures.
447 * This request is always asynchronous.
448 * Success is indicated by returning -EINPROGRESS,
449 * at which time the URB will normally have been unlinked but not yet
450 * given back to the device driver. When it is called, the completion
451 * function will see urb->status == -ECONNRESET. Failure is indicated
452 * by any other return value. Unlinking will fail when the URB is not
453 * currently "linked" (i.e., it was never submitted, or it was unlinked
454 * before, or the hardware is already finished with it), even if the
455 * completion handler has not yet run.
457 * Unlinking and Endpoint Queues:
459 * Host Controller Drivers (HCDs) place all the URBs for a particular
460 * endpoint in a queue. Normally the queue advances as the controller
461 * hardware processes each request. But when an URB terminates with an
462 * error its queue stops, at least until that URB's completion routine
463 * returns. It is guaranteed that the queue will not restart until all
464 * its unlinked URBs have been fully retired, with their completion
465 * routines run, even if that's not until some time after the original
466 * completion handler returns. Normally the same behavior and guarantees
467 * apply when an URB terminates because it was unlinked; however if an
468 * URB is unlinked before the hardware has started to execute it, then
469 * its queue is not guaranteed to stop until all the preceding URBs have
472 * This means that USB device drivers can safely build deep queues for
473 * large or complex transfers, and clean them up reliably after any sort
474 * of aborted transfer by unlinking all pending URBs at the first fault.
476 * Note that an URB terminating early because a short packet was received
477 * will count as an error if and only if the URB_SHORT_NOT_OK flag is set.
478 * Also, that all unlinks performed in any URB completion handler must
481 * Queues for isochronous endpoints are treated differently, because they
482 * advance at fixed rates. Such queues do not stop when an URB is unlinked.
483 * An unlinked URB may leave a gap in the stream of packets. It is undefined
484 * whether such gaps can be filled in.
486 * When a control URB terminates with an error, it is likely that the
487 * status stage of the transfer will not take place, even if it is merely
488 * a soft error resulting from a short-packet with URB_SHORT_NOT_OK set.
490 int usb_unlink_urb(struct urb *urb)
494 if (!(urb->dev && urb->dev->bus))
496 return usb_hcd_unlink_urb(urb, -ECONNRESET);
500 * usb_kill_urb - cancel a transfer request and wait for it to finish
501 * @urb: pointer to URB describing a previously submitted request,
504 * This routine cancels an in-progress request. It is guaranteed that
505 * upon return all completion handlers will have finished and the URB
506 * will be totally idle and available for reuse. These features make
507 * this an ideal way to stop I/O in a disconnect() callback or close()
508 * function. If the request has not already finished or been unlinked
509 * the completion handler will see urb->status == -ENOENT.
511 * While the routine is running, attempts to resubmit the URB will fail
512 * with error -EPERM. Thus even if the URB's completion handler always
513 * tries to resubmit, it will not succeed and the URB will become idle.
515 * This routine may not be used in an interrupt context (such as a bottom
516 * half or a completion handler), or when holding a spinlock, or in other
517 * situations where the caller can't schedule().
519 void usb_kill_urb(struct urb *urb)
522 if (!(urb && urb->dev && urb->dev->bus))
524 spin_lock_irq(&urb->lock);
526 spin_unlock_irq(&urb->lock);
528 usb_hcd_unlink_urb(urb, -ENOENT);
529 wait_event(usb_kill_urb_queue, atomic_read(&urb->use_count) == 0);
531 spin_lock_irq(&urb->lock);
533 spin_unlock_irq(&urb->lock);
537 * usb_kill_anchored_urbs - cancel transfer requests en masse
538 * @anchor: anchor the requests are bound to
540 * this allows all outstanding URBs to be killed starting
541 * from the back of the queue
543 void usb_kill_anchored_urbs(struct usb_anchor *anchor)
547 spin_lock_irq(&anchor->lock);
548 while (!list_empty(&anchor->urb_list)) {
549 victim = list_entry(anchor->urb_list.prev, struct urb, anchor_list);
550 /* we must make sure the URB isn't freed before we kill it*/
552 spin_unlock_irq(&anchor->lock);
553 /* this will unanchor the URB */
554 usb_kill_urb(victim);
556 spin_lock_irq(&anchor->lock);
558 spin_unlock_irq(&anchor->lock);
560 EXPORT_SYMBOL_GPL(usb_kill_anchored_urbs);
563 * usb_wait_anchor_empty_timeout - wait for an anchor to be unused
564 * @anchor: the anchor you want to become unused
565 * @timeout: how long you are willing to wait in milliseconds
567 * Call this is you want to be sure all an anchor's
570 int usb_wait_anchor_empty_timeout(struct usb_anchor *anchor,
571 unsigned int timeout)
573 return wait_event_timeout(anchor->wait, list_empty(&anchor->urb_list),
574 msecs_to_jiffies(timeout));
576 EXPORT_SYMBOL_GPL(usb_wait_anchor_empty_timeout);
578 EXPORT_SYMBOL(usb_init_urb);
579 EXPORT_SYMBOL(usb_alloc_urb);
580 EXPORT_SYMBOL(usb_free_urb);
581 EXPORT_SYMBOL(usb_get_urb);
582 EXPORT_SYMBOL(usb_submit_urb);
583 EXPORT_SYMBOL(usb_unlink_urb);
584 EXPORT_SYMBOL(usb_kill_urb);