1 #include <linux/config.h>
2 #include <linux/module.h>
3 #include <linux/string.h>
4 #include <linux/bitops.h>
5 #include <linux/slab.h>
6 #include <linux/init.h>
8 #ifdef CONFIG_USB_DEBUG
13 #include <linux/usb.h>
16 #define to_urb(d) container_of(d, struct urb, kref)
18 static void urb_destroy(struct kref
*kref
)
20 struct urb
*urb
= to_urb(kref
);
25 * usb_init_urb - initializes a urb so that it can be used by a USB driver
26 * @urb: pointer to the urb to initialize
28 * Initializes a urb so that the USB subsystem can use it properly.
30 * If a urb is created with a call to usb_alloc_urb() it is not
31 * necessary to call this function. Only use this if you allocate the
32 * space for a struct urb on your own. If you call this function, be
33 * careful when freeing the memory for your urb that it is no longer in
34 * use by the USB core.
36 * Only use this function if you _really_ understand what you are doing.
38 void usb_init_urb(struct urb
*urb
)
41 memset(urb
, 0, sizeof(*urb
));
42 kref_init(&urb
->kref
);
43 spin_lock_init(&urb
->lock
);
48 * usb_alloc_urb - creates a new urb for a USB driver to use
49 * @iso_packets: number of iso packets for this urb
50 * @mem_flags: the type of memory to allocate, see kmalloc() for a list of
51 * valid options for this.
53 * Creates an urb for the USB driver to use, initializes a few internal
54 * structures, incrementes the usage counter, and returns a pointer to it.
56 * If no memory is available, NULL is returned.
58 * If the driver want to use this urb for interrupt, control, or bulk
59 * endpoints, pass '0' as the number of iso packets.
61 * The driver must call usb_free_urb() when it is finished with the urb.
63 struct urb
*usb_alloc_urb(int iso_packets
, int mem_flags
)
67 urb
= (struct urb
*)kmalloc(sizeof(struct urb
) +
68 iso_packets
* sizeof(struct usb_iso_packet_descriptor
),
71 err("alloc_urb: kmalloc failed");
79 * usb_free_urb - frees the memory used by a urb when all users of it are finished
80 * @urb: pointer to the urb to free, may be NULL
82 * Must be called when a user of a urb is finished with it. When the last user
83 * of the urb calls this function, the memory of the urb is freed.
85 * Note: The transfer buffer associated with the urb is not freed, that must be
88 void usb_free_urb(struct urb
*urb
)
91 kref_put(&urb
->kref
, urb_destroy
);
95 * usb_get_urb - increments the reference count of the urb
96 * @urb: pointer to the urb to modify, may be NULL
98 * This must be called whenever a urb is transferred from a device driver to a
99 * host controller driver. This allows proper reference counting to happen
102 * A pointer to the urb with the incremented reference counter is returned.
104 struct urb
* usb_get_urb(struct urb
*urb
)
107 kref_get(&urb
->kref
);
112 /*-------------------------------------------------------------------*/
115 * usb_submit_urb - issue an asynchronous transfer request for an endpoint
116 * @urb: pointer to the urb describing the request
117 * @mem_flags: the type of memory to allocate, see kmalloc() for a list
118 * of valid options for this.
120 * This submits a transfer request, and transfers control of the URB
121 * describing that request to the USB subsystem. Request completion will
122 * be indicated later, asynchronously, by calling the completion handler.
123 * The three types of completion are success, error, and unlink
124 * (a software-induced fault, also called "request cancelation").
126 * URBs may be submitted in interrupt context.
128 * The caller must have correctly initialized the URB before submitting
129 * it. Functions such as usb_fill_bulk_urb() and usb_fill_control_urb() are
130 * available to ensure that most fields are correctly initialized, for
131 * the particular kind of transfer, although they will not initialize
132 * any transfer flags.
134 * Successful submissions return 0; otherwise this routine returns a
135 * negative error number. If the submission is successful, the complete()
136 * callback from the URB will be called exactly once, when the USB core and
137 * Host Controller Driver (HCD) are finished with the URB. When the completion
138 * function is called, control of the URB is returned to the device
139 * driver which issued the request. The completion handler may then
140 * immediately free or reuse that URB.
142 * With few exceptions, USB device drivers should never access URB fields
143 * provided by usbcore or the HCD until its complete() is called.
144 * The exceptions relate to periodic transfer scheduling. For both
145 * interrupt and isochronous urbs, as part of successful URB submission
146 * urb->interval is modified to reflect the actual transfer period used
147 * (normally some power of two units). And for isochronous urbs,
148 * urb->start_frame is modified to reflect when the URB's transfers were
149 * scheduled to start. Not all isochronous transfer scheduling policies
150 * will work, but most host controller drivers should easily handle ISO
151 * queues going from now until 10-200 msec into the future.
153 * For control endpoints, the synchronous usb_control_msg() call is
154 * often used (in non-interrupt context) instead of this call.
155 * That is often used through convenience wrappers, for the requests
156 * that are standardized in the USB 2.0 specification. For bulk
157 * endpoints, a synchronous usb_bulk_msg() call is available.
161 * URBs may be submitted to endpoints before previous ones complete, to
162 * minimize the impact of interrupt latencies and system overhead on data
163 * throughput. With that queuing policy, an endpoint's queue would never
164 * be empty. This is required for continuous isochronous data streams,
165 * and may also be required for some kinds of interrupt transfers. Such
166 * queuing also maximizes bandwidth utilization by letting USB controllers
167 * start work on later requests before driver software has finished the
168 * completion processing for earlier (successful) requests.
170 * As of Linux 2.6, all USB endpoint transfer queues support depths greater
171 * than one. This was previously a HCD-specific behavior, except for ISO
172 * transfers. Non-isochronous endpoint queues are inactive during cleanup
173 * after faults (transfer errors or cancelation).
175 * Reserved Bandwidth Transfers:
177 * Periodic transfers (interrupt or isochronous) are performed repeatedly,
178 * using the interval specified in the urb. Submitting the first urb to
179 * the endpoint reserves the bandwidth necessary to make those transfers.
180 * If the USB subsystem can't allocate sufficient bandwidth to perform
181 * the periodic request, submitting such a periodic request should fail.
183 * Device drivers must explicitly request that repetition, by ensuring that
184 * some URB is always on the endpoint's queue (except possibly for short
185 * periods during completion callacks). When there is no longer an urb
186 * queued, the endpoint's bandwidth reservation is canceled. This means
187 * drivers can use their completion handlers to ensure they keep bandwidth
188 * they need, by reinitializing and resubmitting the just-completed urb
189 * until the driver longer needs that periodic bandwidth.
193 * The general rules for how to decide which mem_flags to use
194 * are the same as for kmalloc. There are four
195 * different possible values; GFP_KERNEL, GFP_NOFS, GFP_NOIO and
198 * GFP_NOFS is not ever used, as it has not been implemented yet.
200 * GFP_ATOMIC is used when
201 * (a) you are inside a completion handler, an interrupt, bottom half,
202 * tasklet or timer, or
203 * (b) you are holding a spinlock or rwlock (does not apply to
205 * (c) current->state != TASK_RUNNING, this is the case only after
208 * GFP_NOIO is used in the block io path and error handling of storage
211 * All other situations use GFP_KERNEL.
213 * Some more specific rules for mem_flags can be inferred, such as
214 * (1) start_xmit, timeout, and receive methods of network drivers must
215 * use GFP_ATOMIC (they are called with a spinlock held);
216 * (2) queuecommand methods of scsi drivers must use GFP_ATOMIC (also
217 * called with a spinlock held);
218 * (3) If you use a kernel thread with a network driver you must use
219 * GFP_NOIO, unless (b) or (c) apply;
220 * (4) after you have done a down() you can use GFP_KERNEL, unless (b) or (c)
221 * apply or your are in a storage driver's block io path;
222 * (5) USB probe and disconnect can use GFP_KERNEL unless (b) or (c) apply; and
223 * (6) changing firmware on a running storage or net device uses
224 * GFP_NOIO, unless b) or c) apply
227 int usb_submit_urb(struct urb
*urb
, int mem_flags
)
230 struct usb_device
*dev
;
231 struct usb_operations
*op
;
234 if (!urb
|| urb
->hcpriv
|| !urb
->complete
)
236 if (!(dev
= urb
->dev
) ||
237 (dev
->state
< USB_STATE_DEFAULT
) ||
238 (!dev
->bus
) || (dev
->devnum
<= 0))
240 if (dev
->state
== USB_STATE_SUSPENDED
)
241 return -EHOSTUNREACH
;
242 if (!(op
= dev
->bus
->op
) || !op
->submit_urb
)
245 urb
->status
= -EINPROGRESS
;
246 urb
->actual_length
= 0;
249 /* Lots of sanity checks, so HCDs can rely on clean data
250 * and don't need to duplicate tests
253 temp
= usb_pipetype (pipe
);
254 is_out
= usb_pipeout (pipe
);
256 if (!usb_pipecontrol (pipe
) && dev
->state
< USB_STATE_CONFIGURED
)
259 /* FIXME there should be a sharable lock protecting us against
260 * config/altsetting changes and disconnects, kicking in here.
261 * (here == before maxpacket, and eventually endpoint type,
265 max
= usb_maxpacket (dev
, pipe
, is_out
);
267 dbg ("%s: bogus endpoint %d-%s on usb-%s-%s (bad maxpacket %d)",
269 usb_pipeendpoint (pipe
), is_out
? "OUT" : "IN",
270 dev
->bus
->bus_name
, dev
->devpath
,
275 /* periodic transfers limit size per frame/uframe,
276 * but drivers only control those sizes for ISO.
277 * while we're checking, initialize return status.
279 if (temp
== PIPE_ISOCHRONOUS
) {
282 /* "high bandwidth" mode, 1-3 packets/uframe? */
283 if (dev
->speed
== USB_SPEED_HIGH
) {
284 int mult
= 1 + ((max
>> 11) & 0x03);
289 if (urb
->number_of_packets
<= 0)
291 for (n
= 0; n
< urb
->number_of_packets
; n
++) {
292 len
= urb
->iso_frame_desc
[n
].length
;
293 if (len
< 0 || len
> max
)
295 urb
->iso_frame_desc
[n
].status
= -EXDEV
;
296 urb
->iso_frame_desc
[n
].actual_length
= 0;
300 /* the I/O buffer must be mapped/unmapped, except when length=0 */
301 if (urb
->transfer_buffer_length
< 0)
305 /* stuff that drivers shouldn't do, but which shouldn't
306 * cause problems in HCDs if they get it wrong.
309 unsigned int orig_flags
= urb
->transfer_flags
;
310 unsigned int allowed
;
312 /* enforce simple/standard policy */
313 allowed
= URB_ASYNC_UNLINK
; // affects later unlinks
314 allowed
|= (URB_NO_TRANSFER_DMA_MAP
| URB_NO_SETUP_DMA_MAP
);
315 allowed
|= URB_NO_INTERRUPT
;
319 allowed
|= URB_ZERO_PACKET
;
322 allowed
|= URB_NO_FSBR
; /* only affects UHCI */
324 default: /* all non-iso endpoints */
326 allowed
|= URB_SHORT_NOT_OK
;
328 case PIPE_ISOCHRONOUS
:
329 allowed
|= URB_ISO_ASAP
;
332 urb
->transfer_flags
&= allowed
;
334 /* fail if submitter gave bogus flags */
335 if (urb
->transfer_flags
!= orig_flags
) {
336 err ("BOGUS urb flags, %x --> %x",
337 orig_flags
, urb
->transfer_flags
);
343 * Force periodic transfer intervals to be legal values that are
344 * a power of two (so HCDs don't need to).
346 * FIXME want bus->{intr,iso}_sched_horizon values here. Each HC
347 * supports different values... this uses EHCI/UHCI defaults (and
348 * EHCI can use smaller non-default values).
351 case PIPE_ISOCHRONOUS
:
354 if (urb
->interval
<= 0)
357 switch (dev
->speed
) {
358 case USB_SPEED_HIGH
: /* units are microframes */
359 // NOTE usb handles 2^15
360 if (urb
->interval
> (1024 * 8))
361 urb
->interval
= 1024 * 8;
364 case USB_SPEED_FULL
: /* units are frames/msec */
366 if (temp
== PIPE_INTERRUPT
) {
367 if (urb
->interval
> 255)
369 // NOTE ohci only handles up to 32
372 if (urb
->interval
> 1024)
373 urb
->interval
= 1024;
374 // NOTE usb and ohci handle up to 2^15
382 while (temp
> urb
->interval
)
384 urb
->interval
= temp
;
387 return op
->submit_urb (urb
, mem_flags
);
390 /*-------------------------------------------------------------------*/
393 * usb_unlink_urb - abort/cancel a transfer request for an endpoint
394 * @urb: pointer to urb describing a previously submitted request,
397 * This routine cancels an in-progress request. URBs complete only
398 * once per submission, and may be canceled only once per submission.
399 * Successful cancelation means the requests's completion handler will
400 * be called with a status code indicating that the request has been
401 * canceled (rather than any other code) and will quickly be removed
402 * from host controller data structures.
404 * In the past, clearing the URB_ASYNC_UNLINK transfer flag for the
405 * URB indicated that the request was synchronous. This usage is now
406 * deprecated; if the flag is clear the call will be forwarded to
407 * usb_kill_urb() and the return value will be 0. In the future, drivers
408 * should call usb_kill_urb() directly for synchronous unlinking.
410 * When the URB_ASYNC_UNLINK transfer flag for the URB is set, this
411 * request is asynchronous. Success is indicated by returning -EINPROGRESS,
412 * at which time the URB will normally have been unlinked but not yet
413 * given back to the device driver. When it is called, the completion
414 * function will see urb->status == -ECONNRESET. Failure is indicated
415 * by any other return value. Unlinking will fail when the URB is not
416 * currently "linked" (i.e., it was never submitted, or it was unlinked
417 * before, or the hardware is already finished with it), even if the
418 * completion handler has not yet run.
420 * Unlinking and Endpoint Queues:
422 * Host Controller Drivers (HCDs) place all the URBs for a particular
423 * endpoint in a queue. Normally the queue advances as the controller
424 * hardware processes each request. But when an URB terminates with any
425 * fault (such as an error, or being unlinked) its queue stops, at least
426 * until that URB's completion routine returns. It is guaranteed that
427 * the queue will not restart until all its unlinked URBs have been fully
428 * retired, with their completion routines run, even if that's not until
429 * some time after the original completion handler returns.
431 * This means that USB device drivers can safely build deep queues for
432 * large or complex transfers, and clean them up reliably after any sort
433 * of aborted transfer by unlinking all pending URBs at the first fault.
435 * Note that an URB terminating early because a short packet was received
436 * will count as an error if and only if the URB_SHORT_NOT_OK flag is set.
437 * Also, that all unlinks performed in any URB completion handler must
440 * Queues for isochronous endpoints are treated differently, because they
441 * advance at fixed rates. Such queues do not stop when an URB is unlinked.
442 * An unlinked URB may leave a gap in the stream of packets. It is undefined
443 * whether such gaps can be filled in.
445 * When a control URB terminates with an error, it is likely that the
446 * status stage of the transfer will not take place, even if it is merely
447 * a soft error resulting from a short-packet with URB_SHORT_NOT_OK set.
449 int usb_unlink_urb(struct urb
*urb
)
453 if (!(urb
->transfer_flags
& URB_ASYNC_UNLINK
)) {
457 if (!(urb
->dev
&& urb
->dev
->bus
&& urb
->dev
->bus
->op
))
459 return urb
->dev
->bus
->op
->unlink_urb(urb
, -ECONNRESET
);
463 * usb_kill_urb - cancel a transfer request and wait for it to finish
464 * @urb: pointer to URB describing a previously submitted request,
467 * This routine cancels an in-progress request. It is guaranteed that
468 * upon return all completion handlers will have finished and the URB
469 * will be totally idle and available for reuse. These features make
470 * this an ideal way to stop I/O in a disconnect() callback or close()
471 * function. If the request has not already finished or been unlinked
472 * the completion handler will see urb->status == -ENOENT.
474 * While the routine is running, attempts to resubmit the URB will fail
475 * with error -EPERM. Thus even if the URB's completion handler always
476 * tries to resubmit, it will not succeed and the URB will become idle.
478 * This routine may not be used in an interrupt context (such as a bottom
479 * half or a completion handler), or when holding a spinlock, or in other
480 * situations where the caller can't schedule().
482 void usb_kill_urb(struct urb
*urb
)
484 if (!(urb
&& urb
->dev
&& urb
->dev
->bus
&& urb
->dev
->bus
->op
))
486 spin_lock_irq(&urb
->lock
);
488 spin_unlock_irq(&urb
->lock
);
490 urb
->dev
->bus
->op
->unlink_urb(urb
, -ENOENT
);
491 wait_event(usb_kill_urb_queue
, atomic_read(&urb
->use_count
) == 0);
493 spin_lock_irq(&urb
->lock
);
495 spin_unlock_irq(&urb
->lock
);
498 EXPORT_SYMBOL(usb_init_urb
);
499 EXPORT_SYMBOL(usb_alloc_urb
);
500 EXPORT_SYMBOL(usb_free_urb
);
501 EXPORT_SYMBOL(usb_get_urb
);
502 EXPORT_SYMBOL(usb_submit_urb
);
503 EXPORT_SYMBOL(usb_unlink_urb
);
504 EXPORT_SYMBOL(usb_kill_urb
);