blob: dc838f81742cb1c848ea084e07266d1cd7477c52 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001#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>
7
8#ifdef CONFIG_USB_DEBUG
9 #define DEBUG
10#else
11 #undef DEBUG
12#endif
13#include <linux/usb.h>
14#include "hcd.h"
15
16#define to_urb(d) container_of(d, struct urb, kref)
17
18static void urb_destroy(struct kref *kref)
19{
20 struct urb *urb = to_urb(kref);
21 kfree(urb);
22}
23
24/**
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
27 *
28 * Initializes a urb so that the USB subsystem can use it properly.
29 *
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.
35 *
36 * Only use this function if you _really_ understand what you are doing.
37 */
38void usb_init_urb(struct urb *urb)
39{
40 if (urb) {
41 memset(urb, 0, sizeof(*urb));
42 kref_init(&urb->kref);
43 spin_lock_init(&urb->lock);
44 }
45}
46
47/**
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.
52 *
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.
55 *
56 * If no memory is available, NULL is returned.
57 *
58 * If the driver want to use this urb for interrupt, control, or bulk
59 * endpoints, pass '0' as the number of iso packets.
60 *
61 * The driver must call usb_free_urb() when it is finished with the urb.
62 */
63struct urb *usb_alloc_urb(int iso_packets, int mem_flags)
64{
65 struct urb *urb;
66
67 urb = (struct urb *)kmalloc(sizeof(struct urb) +
68 iso_packets * sizeof(struct usb_iso_packet_descriptor),
69 mem_flags);
70 if (!urb) {
71 err("alloc_urb: kmalloc failed");
72 return NULL;
73 }
74 usb_init_urb(urb);
75 return urb;
76}
77
78/**
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
81 *
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.
84 *
85 * Note: The transfer buffer associated with the urb is not freed, that must be
86 * done elsewhere.
87 */
88void usb_free_urb(struct urb *urb)
89{
90 if (urb)
91 kref_put(&urb->kref, urb_destroy);
92}
93
94/**
95 * usb_get_urb - increments the reference count of the urb
96 * @urb: pointer to the urb to modify, may be NULL
97 *
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
100 * for urbs.
101 *
102 * A pointer to the urb with the incremented reference counter is returned.
103 */
104struct urb * usb_get_urb(struct urb *urb)
105{
106 if (urb)
107 kref_get(&urb->kref);
108 return urb;
109}
110
111
112/*-------------------------------------------------------------------*/
113
114/**
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.
119 *
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").
125 *
126 * URBs may be submitted in interrupt context.
127 *
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.
133 *
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.
141 *
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.
152 *
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.
158 *
159 * Request Queuing:
160 *
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.
169 *
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).
174 *
175 * Reserved Bandwidth Transfers:
176 *
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.
182 *
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.
190 *
191 * Memory Flags:
192 *
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
196 * GFP_ATOMIC.
197 *
198 * GFP_NOFS is not ever used, as it has not been implemented yet.
199 *
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
204 * semaphores), or
205 * (c) current->state != TASK_RUNNING, this is the case only after
206 * you've changed it.
207 *
208 * GFP_NOIO is used in the block io path and error handling of storage
209 * devices.
210 *
211 * All other situations use GFP_KERNEL.
212 *
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
225 *
226 */
227int usb_submit_urb(struct urb *urb, int mem_flags)
228{
229 int pipe, temp, max;
230 struct usb_device *dev;
231 struct usb_operations *op;
232 int is_out;
233
234 if (!urb || urb->hcpriv || !urb->complete)
235 return -EINVAL;
236 if (!(dev = urb->dev) ||
237 (dev->state < USB_STATE_DEFAULT) ||
238 (!dev->bus) || (dev->devnum <= 0))
239 return -ENODEV;
240 if (dev->state == USB_STATE_SUSPENDED)
241 return -EHOSTUNREACH;
242 if (!(op = dev->bus->op) || !op->submit_urb)
243 return -ENODEV;
244
245 urb->status = -EINPROGRESS;
246 urb->actual_length = 0;
247 urb->bandwidth = 0;
248
249 /* Lots of sanity checks, so HCDs can rely on clean data
250 * and don't need to duplicate tests
251 */
252 pipe = urb->pipe;
253 temp = usb_pipetype (pipe);
254 is_out = usb_pipeout (pipe);
255
256 if (!usb_pipecontrol (pipe) && dev->state < USB_STATE_CONFIGURED)
257 return -ENODEV;
258
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,
262 * checks get made.)
263 */
264
265 max = usb_maxpacket (dev, pipe, is_out);
266 if (max <= 0) {
267 dev_dbg(&dev->dev,
268 "bogus endpoint ep%d%s in %s (bad maxpacket %d)\n",
269 usb_pipeendpoint (pipe), is_out ? "out" : "in",
270 __FUNCTION__, max);
271 return -EMSGSIZE;
272 }
273
274 /* periodic transfers limit size per frame/uframe,
275 * but drivers only control those sizes for ISO.
276 * while we're checking, initialize return status.
277 */
278 if (temp == PIPE_ISOCHRONOUS) {
279 int n, len;
280
281 /* "high bandwidth" mode, 1-3 packets/uframe? */
282 if (dev->speed == USB_SPEED_HIGH) {
283 int mult = 1 + ((max >> 11) & 0x03);
284 max &= 0x07ff;
285 max *= mult;
286 }
287
288 if (urb->number_of_packets <= 0)
289 return -EINVAL;
290 for (n = 0; n < urb->number_of_packets; n++) {
291 len = urb->iso_frame_desc [n].length;
292 if (len < 0 || len > max)
293 return -EMSGSIZE;
294 urb->iso_frame_desc [n].status = -EXDEV;
295 urb->iso_frame_desc [n].actual_length = 0;
296 }
297 }
298
299 /* the I/O buffer must be mapped/unmapped, except when length=0 */
300 if (urb->transfer_buffer_length < 0)
301 return -EMSGSIZE;
302
303#ifdef DEBUG
304 /* stuff that drivers shouldn't do, but which shouldn't
305 * cause problems in HCDs if they get it wrong.
306 */
307 {
308 unsigned int orig_flags = urb->transfer_flags;
309 unsigned int allowed;
310
311 /* enforce simple/standard policy */
312 allowed = URB_ASYNC_UNLINK; // affects later unlinks
313 allowed |= (URB_NO_TRANSFER_DMA_MAP | URB_NO_SETUP_DMA_MAP);
314 allowed |= URB_NO_INTERRUPT;
315 switch (temp) {
316 case PIPE_BULK:
317 if (is_out)
318 allowed |= URB_ZERO_PACKET;
319 /* FALLTHROUGH */
320 case PIPE_CONTROL:
321 allowed |= URB_NO_FSBR; /* only affects UHCI */
322 /* FALLTHROUGH */
323 default: /* all non-iso endpoints */
324 if (!is_out)
325 allowed |= URB_SHORT_NOT_OK;
326 break;
327 case PIPE_ISOCHRONOUS:
328 allowed |= URB_ISO_ASAP;
329 break;
330 }
331 urb->transfer_flags &= allowed;
332
333 /* fail if submitter gave bogus flags */
334 if (urb->transfer_flags != orig_flags) {
335 err ("BOGUS urb flags, %x --> %x",
336 orig_flags, urb->transfer_flags);
337 return -EINVAL;
338 }
339 }
340#endif
341 /*
342 * Force periodic transfer intervals to be legal values that are
343 * a power of two (so HCDs don't need to).
344 *
345 * FIXME want bus->{intr,iso}_sched_horizon values here. Each HC
346 * supports different values... this uses EHCI/UHCI defaults (and
347 * EHCI can use smaller non-default values).
348 */
349 switch (temp) {
350 case PIPE_ISOCHRONOUS:
351 case PIPE_INTERRUPT:
352 /* too small? */
353 if (urb->interval <= 0)
354 return -EINVAL;
355 /* too big? */
356 switch (dev->speed) {
357 case USB_SPEED_HIGH: /* units are microframes */
358 // NOTE usb handles 2^15
359 if (urb->interval > (1024 * 8))
360 urb->interval = 1024 * 8;
361 temp = 1024 * 8;
362 break;
363 case USB_SPEED_FULL: /* units are frames/msec */
364 case USB_SPEED_LOW:
365 if (temp == PIPE_INTERRUPT) {
366 if (urb->interval > 255)
367 return -EINVAL;
368 // NOTE ohci only handles up to 32
369 temp = 128;
370 } else {
371 if (urb->interval > 1024)
372 urb->interval = 1024;
373 // NOTE usb and ohci handle up to 2^15
374 temp = 1024;
375 }
376 break;
377 default:
378 return -EINVAL;
379 }
380 /* power of two? */
381 while (temp > urb->interval)
382 temp >>= 1;
383 urb->interval = temp;
384 }
385
386 return op->submit_urb (urb, mem_flags);
387}
388
389/*-------------------------------------------------------------------*/
390
391/**
392 * usb_unlink_urb - abort/cancel a transfer request for an endpoint
393 * @urb: pointer to urb describing a previously submitted request,
394 * may be NULL
395 *
396 * This routine cancels an in-progress request. URBs complete only
397 * once per submission, and may be canceled only once per submission.
398 * Successful cancelation means the requests's completion handler will
399 * be called with a status code indicating that the request has been
400 * canceled (rather than any other code) and will quickly be removed
401 * from host controller data structures.
402 *
403 * In the past, clearing the URB_ASYNC_UNLINK transfer flag for the
404 * URB indicated that the request was synchronous. This usage is now
405 * deprecated; if the flag is clear the call will be forwarded to
406 * usb_kill_urb() and the return value will be 0. In the future, drivers
407 * should call usb_kill_urb() directly for synchronous unlinking.
408 *
409 * When the URB_ASYNC_UNLINK transfer flag for the URB is set, this
410 * request is asynchronous. Success is indicated by returning -EINPROGRESS,
411 * at which time the URB will normally have been unlinked but not yet
412 * given back to the device driver. When it is called, the completion
413 * function will see urb->status == -ECONNRESET. Failure is indicated
414 * by any other return value. Unlinking will fail when the URB is not
415 * currently "linked" (i.e., it was never submitted, or it was unlinked
416 * before, or the hardware is already finished with it), even if the
417 * completion handler has not yet run.
418 *
419 * Unlinking and Endpoint Queues:
420 *
421 * Host Controller Drivers (HCDs) place all the URBs for a particular
422 * endpoint in a queue. Normally the queue advances as the controller
423 * hardware processes each request. But when an URB terminates with any
424 * fault (such as an error, or being unlinked) its queue stops, at least
425 * until that URB's completion routine returns. It is guaranteed that
426 * the queue will not restart until all its unlinked URBs have been fully
427 * retired, with their completion routines run, even if that's not until
428 * some time after the original completion handler returns.
429 *
430 * This means that USB device drivers can safely build deep queues for
431 * large or complex transfers, and clean them up reliably after any sort
432 * of aborted transfer by unlinking all pending URBs at the first fault.
433 *
434 * Note that an URB terminating early because a short packet was received
435 * will count as an error if and only if the URB_SHORT_NOT_OK flag is set.
436 * Also, that all unlinks performed in any URB completion handler must
437 * be asynchronous.
438 *
439 * Queues for isochronous endpoints are treated differently, because they
440 * advance at fixed rates. Such queues do not stop when an URB is unlinked.
441 * An unlinked URB may leave a gap in the stream of packets. It is undefined
442 * whether such gaps can be filled in.
443 *
444 * When a control URB terminates with an error, it is likely that the
445 * status stage of the transfer will not take place, even if it is merely
446 * a soft error resulting from a short-packet with URB_SHORT_NOT_OK set.
447 */
448int usb_unlink_urb(struct urb *urb)
449{
450 if (!urb)
451 return -EINVAL;
452 if (!(urb->transfer_flags & URB_ASYNC_UNLINK)) {
453#ifdef CONFIG_DEBUG_KERNEL
454 if (printk_ratelimit()) {
455 printk(KERN_NOTICE "usb_unlink_urb() is deprecated for "
456 "synchronous unlinks. Use usb_kill_urb() instead.\n");
457 WARN_ON(1);
458 }
459#endif
460 usb_kill_urb(urb);
461 return 0;
462 }
463 if (!(urb->dev && urb->dev->bus && urb->dev->bus->op))
464 return -ENODEV;
465 return urb->dev->bus->op->unlink_urb(urb, -ECONNRESET);
466}
467
468/**
469 * usb_kill_urb - cancel a transfer request and wait for it to finish
470 * @urb: pointer to URB describing a previously submitted request,
471 * may be NULL
472 *
473 * This routine cancels an in-progress request. It is guaranteed that
474 * upon return all completion handlers will have finished and the URB
475 * will be totally idle and available for reuse. These features make
476 * this an ideal way to stop I/O in a disconnect() callback or close()
477 * function. If the request has not already finished or been unlinked
478 * the completion handler will see urb->status == -ENOENT.
479 *
480 * While the routine is running, attempts to resubmit the URB will fail
481 * with error -EPERM. Thus even if the URB's completion handler always
482 * tries to resubmit, it will not succeed and the URB will become idle.
483 *
484 * This routine may not be used in an interrupt context (such as a bottom
485 * half or a completion handler), or when holding a spinlock, or in other
486 * situations where the caller can't schedule().
487 */
488void usb_kill_urb(struct urb *urb)
489{
490 if (!(urb && urb->dev && urb->dev->bus && urb->dev->bus->op))
491 return;
492 spin_lock_irq(&urb->lock);
493 ++urb->reject;
494 spin_unlock_irq(&urb->lock);
495
496 urb->dev->bus->op->unlink_urb(urb, -ENOENT);
497 wait_event(usb_kill_urb_queue, atomic_read(&urb->use_count) == 0);
498
499 spin_lock_irq(&urb->lock);
500 --urb->reject;
501 spin_unlock_irq(&urb->lock);
502}
503
504EXPORT_SYMBOL(usb_init_urb);
505EXPORT_SYMBOL(usb_alloc_urb);
506EXPORT_SYMBOL(usb_free_urb);
507EXPORT_SYMBOL(usb_get_urb);
508EXPORT_SYMBOL(usb_submit_urb);
509EXPORT_SYMBOL(usb_unlink_urb);
510EXPORT_SYMBOL(usb_kill_urb);
511