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>
9 #define to_urb(d) container_of(d, struct urb, kref)
11 static void urb_destroy(struct kref
*kref
)
13 struct urb
*urb
= to_urb(kref
);
18 * usb_init_urb - initializes a urb so that it can be used by a USB driver
19 * @urb: pointer to the urb to initialize
21 * Initializes a urb so that the USB subsystem can use it properly.
23 * If a urb is created with a call to usb_alloc_urb() it is not
24 * necessary to call this function. Only use this if you allocate the
25 * space for a struct urb on your own. If you call this function, be
26 * careful when freeing the memory for your urb that it is no longer in
27 * use by the USB core.
29 * Only use this function if you _really_ understand what you are doing.
31 void usb_init_urb(struct urb
*urb
)
34 memset(urb
, 0, sizeof(*urb
));
35 kref_init(&urb
->kref
);
36 spin_lock_init(&urb
->lock
);
41 * usb_alloc_urb - creates a new urb for a USB driver to use
42 * @iso_packets: number of iso packets for this urb
43 * @mem_flags: the type of memory to allocate, see kmalloc() for a list of
44 * valid options for this.
46 * Creates an urb for the USB driver to use, initializes a few internal
47 * structures, incrementes the usage counter, and returns a pointer to it.
49 * If no memory is available, NULL is returned.
51 * If the driver want to use this urb for interrupt, control, or bulk
52 * endpoints, pass '0' as the number of iso packets.
54 * The driver must call usb_free_urb() when it is finished with the urb.
56 struct urb
*usb_alloc_urb(int iso_packets
, gfp_t mem_flags
)
60 urb
= (struct urb
*)kmalloc(sizeof(struct urb
) +
61 iso_packets
* sizeof(struct usb_iso_packet_descriptor
),
64 err("alloc_urb: kmalloc failed");
72 * usb_free_urb - frees the memory used by a urb when all users of it are finished
73 * @urb: pointer to the urb to free, may be NULL
75 * Must be called when a user of a urb is finished with it. When the last user
76 * of the urb calls this function, the memory of the urb is freed.
78 * Note: The transfer buffer associated with the urb is not freed, that must be
81 void usb_free_urb(struct urb
*urb
)
84 kref_put(&urb
->kref
, urb_destroy
);
88 * usb_get_urb - increments the reference count of the urb
89 * @urb: pointer to the urb to modify, may be NULL
91 * This must be called whenever a urb is transferred from a device driver to a
92 * host controller driver. This allows proper reference counting to happen
95 * A pointer to the urb with the incremented reference counter is returned.
97 struct urb
* usb_get_urb(struct urb
*urb
)
100 kref_get(&urb
->kref
);
105 /*-------------------------------------------------------------------*/
108 * usb_submit_urb - issue an asynchronous transfer request for an endpoint
109 * @urb: pointer to the urb describing the request
110 * @mem_flags: the type of memory to allocate, see kmalloc() for a list
111 * of valid options for this.
113 * This submits a transfer request, and transfers control of the URB
114 * describing that request to the USB subsystem. Request completion will
115 * be indicated later, asynchronously, by calling the completion handler.
116 * The three types of completion are success, error, and unlink
117 * (a software-induced fault, also called "request cancellation").
119 * URBs may be submitted in interrupt context.
121 * The caller must have correctly initialized the URB before submitting
122 * it. Functions such as usb_fill_bulk_urb() and usb_fill_control_urb() are
123 * available to ensure that most fields are correctly initialized, for
124 * the particular kind of transfer, although they will not initialize
125 * any transfer flags.
127 * Successful submissions return 0; otherwise this routine returns a
128 * negative error number. If the submission is successful, the complete()
129 * callback from the URB will be called exactly once, when the USB core and
130 * Host Controller Driver (HCD) are finished with the URB. When the completion
131 * function is called, control of the URB is returned to the device
132 * driver which issued the request. The completion handler may then
133 * immediately free or reuse that URB.
135 * With few exceptions, USB device drivers should never access URB fields
136 * provided by usbcore or the HCD until its complete() is called.
137 * The exceptions relate to periodic transfer scheduling. For both
138 * interrupt and isochronous urbs, as part of successful URB submission
139 * urb->interval is modified to reflect the actual transfer period used
140 * (normally some power of two units). And for isochronous urbs,
141 * urb->start_frame is modified to reflect when the URB's transfers were
142 * scheduled to start. Not all isochronous transfer scheduling policies
143 * will work, but most host controller drivers should easily handle ISO
144 * queues going from now until 10-200 msec into the future.
146 * For control endpoints, the synchronous usb_control_msg() call is
147 * often used (in non-interrupt context) instead of this call.
148 * That is often used through convenience wrappers, for the requests
149 * that are standardized in the USB 2.0 specification. For bulk
150 * endpoints, a synchronous usb_bulk_msg() call is available.
154 * URBs may be submitted to endpoints before previous ones complete, to
155 * minimize the impact of interrupt latencies and system overhead on data
156 * throughput. With that queuing policy, an endpoint's queue would never
157 * be empty. This is required for continuous isochronous data streams,
158 * and may also be required for some kinds of interrupt transfers. Such
159 * queuing also maximizes bandwidth utilization by letting USB controllers
160 * start work on later requests before driver software has finished the
161 * completion processing for earlier (successful) requests.
163 * As of Linux 2.6, all USB endpoint transfer queues support depths greater
164 * than one. This was previously a HCD-specific behavior, except for ISO
165 * transfers. Non-isochronous endpoint queues are inactive during cleanup
166 * after faults (transfer errors or cancellation).
168 * Reserved Bandwidth Transfers:
170 * Periodic transfers (interrupt or isochronous) are performed repeatedly,
171 * using the interval specified in the urb. Submitting the first urb to
172 * the endpoint reserves the bandwidth necessary to make those transfers.
173 * If the USB subsystem can't allocate sufficient bandwidth to perform
174 * the periodic request, submitting such a periodic request should fail.
176 * Device drivers must explicitly request that repetition, by ensuring that
177 * some URB is always on the endpoint's queue (except possibly for short
178 * periods during completion callacks). When there is no longer an urb
179 * queued, the endpoint's bandwidth reservation is canceled. This means
180 * drivers can use their completion handlers to ensure they keep bandwidth
181 * they need, by reinitializing and resubmitting the just-completed urb
182 * until the driver longer needs that periodic bandwidth.
186 * The general rules for how to decide which mem_flags to use
187 * are the same as for kmalloc. There are four
188 * different possible values; GFP_KERNEL, GFP_NOFS, GFP_NOIO and
191 * GFP_NOFS is not ever used, as it has not been implemented yet.
193 * GFP_ATOMIC is used when
194 * (a) you are inside a completion handler, an interrupt, bottom half,
195 * tasklet or timer, or
196 * (b) you are holding a spinlock or rwlock (does not apply to
198 * (c) current->state != TASK_RUNNING, this is the case only after
201 * GFP_NOIO is used in the block io path and error handling of storage
204 * All other situations use GFP_KERNEL.
206 * Some more specific rules for mem_flags can be inferred, such as
207 * (1) start_xmit, timeout, and receive methods of network drivers must
208 * use GFP_ATOMIC (they are called with a spinlock held);
209 * (2) queuecommand methods of scsi drivers must use GFP_ATOMIC (also
210 * called with a spinlock held);
211 * (3) If you use a kernel thread with a network driver you must use
212 * GFP_NOIO, unless (b) or (c) apply;
213 * (4) after you have done a down() you can use GFP_KERNEL, unless (b) or (c)
214 * apply or your are in a storage driver's block io path;
215 * (5) USB probe and disconnect can use GFP_KERNEL unless (b) or (c) apply; and
216 * (6) changing firmware on a running storage or net device uses
217 * GFP_NOIO, unless b) or c) apply
220 int usb_submit_urb(struct urb
*urb
, gfp_t mem_flags
)
223 struct usb_device
*dev
;
224 struct usb_operations
*op
;
227 if (!urb
|| urb
->hcpriv
|| !urb
->complete
)
229 if (!(dev
= urb
->dev
) ||
230 (dev
->state
< USB_STATE_DEFAULT
) ||
231 (!dev
->bus
) || (dev
->devnum
<= 0))
233 if (dev
->bus
->controller
->power
.power_state
.event
!= PM_EVENT_ON
234 || dev
->state
== USB_STATE_SUSPENDED
)
235 return -EHOSTUNREACH
;
236 if (!(op
= dev
->bus
->op
) || !op
->submit_urb
)
239 urb
->status
= -EINPROGRESS
;
240 urb
->actual_length
= 0;
243 /* Lots of sanity checks, so HCDs can rely on clean data
244 * and don't need to duplicate tests
247 temp
= usb_pipetype (pipe
);
248 is_out
= usb_pipeout (pipe
);
250 if (!usb_pipecontrol (pipe
) && dev
->state
< USB_STATE_CONFIGURED
)
253 /* FIXME there should be a sharable lock protecting us against
254 * config/altsetting changes and disconnects, kicking in here.
255 * (here == before maxpacket, and eventually endpoint type,
259 max
= usb_maxpacket (dev
, pipe
, is_out
);
262 "bogus endpoint ep%d%s in %s (bad maxpacket %d)\n",
263 usb_pipeendpoint (pipe
), is_out
? "out" : "in",
268 /* periodic transfers limit size per frame/uframe,
269 * but drivers only control those sizes for ISO.
270 * while we're checking, initialize return status.
272 if (temp
== PIPE_ISOCHRONOUS
) {
275 /* "high bandwidth" mode, 1-3 packets/uframe? */
276 if (dev
->speed
== USB_SPEED_HIGH
) {
277 int mult
= 1 + ((max
>> 11) & 0x03);
282 if (urb
->number_of_packets
<= 0)
284 for (n
= 0; n
< urb
->number_of_packets
; n
++) {
285 len
= urb
->iso_frame_desc
[n
].length
;
286 if (len
< 0 || len
> max
)
288 urb
->iso_frame_desc
[n
].status
= -EXDEV
;
289 urb
->iso_frame_desc
[n
].actual_length
= 0;
293 /* the I/O buffer must be mapped/unmapped, except when length=0 */
294 if (urb
->transfer_buffer_length
< 0)
298 /* stuff that drivers shouldn't do, but which shouldn't
299 * cause problems in HCDs if they get it wrong.
302 unsigned int orig_flags
= urb
->transfer_flags
;
303 unsigned int allowed
;
305 /* enforce simple/standard policy */
306 allowed
= (URB_NO_TRANSFER_DMA_MAP
| URB_NO_SETUP_DMA_MAP
|
311 allowed
|= URB_ZERO_PACKET
;
314 allowed
|= URB_NO_FSBR
; /* only affects UHCI */
316 default: /* all non-iso endpoints */
318 allowed
|= URB_SHORT_NOT_OK
;
320 case PIPE_ISOCHRONOUS
:
321 allowed
|= URB_ISO_ASAP
;
324 urb
->transfer_flags
&= allowed
;
326 /* fail if submitter gave bogus flags */
327 if (urb
->transfer_flags
!= orig_flags
) {
328 err ("BOGUS urb flags, %x --> %x",
329 orig_flags
, urb
->transfer_flags
);
335 * Force periodic transfer intervals to be legal values that are
336 * a power of two (so HCDs don't need to).
338 * FIXME want bus->{intr,iso}_sched_horizon values here. Each HC
339 * supports different values... this uses EHCI/UHCI defaults (and
340 * EHCI can use smaller non-default values).
343 case PIPE_ISOCHRONOUS
:
346 if (urb
->interval
<= 0)
349 switch (dev
->speed
) {
350 case USB_SPEED_HIGH
: /* units are microframes */
351 // NOTE usb handles 2^15
352 if (urb
->interval
> (1024 * 8))
353 urb
->interval
= 1024 * 8;
356 case USB_SPEED_FULL
: /* units are frames/msec */
358 if (temp
== PIPE_INTERRUPT
) {
359 if (urb
->interval
> 255)
361 // NOTE ohci only handles up to 32
364 if (urb
->interval
> 1024)
365 urb
->interval
= 1024;
366 // NOTE usb and ohci handle up to 2^15
374 while (temp
> urb
->interval
)
376 urb
->interval
= temp
;
379 return op
->submit_urb (urb
, mem_flags
);
382 /*-------------------------------------------------------------------*/
385 * usb_unlink_urb - abort/cancel a transfer request for an endpoint
386 * @urb: pointer to urb describing a previously submitted request,
389 * This routine cancels an in-progress request. URBs complete only
390 * once per submission, and may be canceled only once per submission.
391 * Successful cancellation means the requests's completion handler will
392 * be called with a status code indicating that the request has been
393 * canceled (rather than any other code) and will quickly be removed
394 * from host controller data structures.
396 * This request is always asynchronous.
397 * Success is indicated by returning -EINPROGRESS,
398 * at which time the URB will normally have been unlinked but not yet
399 * given back to the device driver. When it is called, the completion
400 * function will see urb->status == -ECONNRESET. Failure is indicated
401 * by any other return value. Unlinking will fail when the URB is not
402 * currently "linked" (i.e., it was never submitted, or it was unlinked
403 * before, or the hardware is already finished with it), even if the
404 * completion handler has not yet run.
406 * Unlinking and Endpoint Queues:
408 * Host Controller Drivers (HCDs) place all the URBs for a particular
409 * endpoint in a queue. Normally the queue advances as the controller
410 * hardware processes each request. But when an URB terminates with an
411 * error its queue stops, at least until that URB's completion routine
412 * returns. It is guaranteed that the queue will not restart until all
413 * its unlinked URBs have been fully retired, with their completion
414 * routines run, even if that's not until some time after the original
415 * completion handler returns. Normally the same behavior and guarantees
416 * apply when an URB terminates because it was unlinked; however if an
417 * URB is unlinked before the hardware has started to execute it, then
418 * its queue is not guaranteed to stop until all the preceding URBs have
421 * This means that USB device drivers can safely build deep queues for
422 * large or complex transfers, and clean them up reliably after any sort
423 * of aborted transfer by unlinking all pending URBs at the first fault.
425 * Note that an URB terminating early because a short packet was received
426 * will count as an error if and only if the URB_SHORT_NOT_OK flag is set.
427 * Also, that all unlinks performed in any URB completion handler must
430 * Queues for isochronous endpoints are treated differently, because they
431 * advance at fixed rates. Such queues do not stop when an URB is unlinked.
432 * An unlinked URB may leave a gap in the stream of packets. It is undefined
433 * whether such gaps can be filled in.
435 * When a control URB terminates with an error, it is likely that the
436 * status stage of the transfer will not take place, even if it is merely
437 * a soft error resulting from a short-packet with URB_SHORT_NOT_OK set.
439 int usb_unlink_urb(struct urb
*urb
)
443 if (!(urb
->dev
&& urb
->dev
->bus
&& urb
->dev
->bus
->op
))
445 return urb
->dev
->bus
->op
->unlink_urb(urb
, -ECONNRESET
);
449 * usb_kill_urb - cancel a transfer request and wait for it to finish
450 * @urb: pointer to URB describing a previously submitted request,
453 * This routine cancels an in-progress request. It is guaranteed that
454 * upon return all completion handlers will have finished and the URB
455 * will be totally idle and available for reuse. These features make
456 * this an ideal way to stop I/O in a disconnect() callback or close()
457 * function. If the request has not already finished or been unlinked
458 * the completion handler will see urb->status == -ENOENT.
460 * While the routine is running, attempts to resubmit the URB will fail
461 * with error -EPERM. Thus even if the URB's completion handler always
462 * tries to resubmit, it will not succeed and the URB will become idle.
464 * This routine may not be used in an interrupt context (such as a bottom
465 * half or a completion handler), or when holding a spinlock, or in other
466 * situations where the caller can't schedule().
468 void usb_kill_urb(struct urb
*urb
)
471 if (!(urb
&& urb
->dev
&& urb
->dev
->bus
&& urb
->dev
->bus
->op
))
473 spin_lock_irq(&urb
->lock
);
475 spin_unlock_irq(&urb
->lock
);
477 urb
->dev
->bus
->op
->unlink_urb(urb
, -ENOENT
);
478 wait_event(usb_kill_urb_queue
, atomic_read(&urb
->use_count
) == 0);
480 spin_lock_irq(&urb
->lock
);
482 spin_unlock_irq(&urb
->lock
);
485 EXPORT_SYMBOL(usb_init_urb
);
486 EXPORT_SYMBOL(usb_alloc_urb
);
487 EXPORT_SYMBOL(usb_free_urb
);
488 EXPORT_SYMBOL(usb_get_urb
);
489 EXPORT_SYMBOL(usb_submit_urb
);
490 EXPORT_SYMBOL(usb_unlink_urb
);
491 EXPORT_SYMBOL(usb_kill_urb
);