xref: /openbmc/linux/sound/usb/endpoint.c (revision 9cfc5c90)
1 /*
2  *   This program is free software; you can redistribute it and/or modify
3  *   it under the terms of the GNU General Public License as published by
4  *   the Free Software Foundation; either version 2 of the License, or
5  *   (at your option) any later version.
6  *
7  *   This program is distributed in the hope that it will be useful,
8  *   but WITHOUT ANY WARRANTY; without even the implied warranty of
9  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
10  *   GNU General Public License for more details.
11  *
12  *   You should have received a copy of the GNU General Public License
13  *   along with this program; if not, write to the Free Software
14  *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
15  *
16  */
17 
18 #include <linux/gfp.h>
19 #include <linux/init.h>
20 #include <linux/ratelimit.h>
21 #include <linux/usb.h>
22 #include <linux/usb/audio.h>
23 #include <linux/slab.h>
24 
25 #include <sound/core.h>
26 #include <sound/pcm.h>
27 #include <sound/pcm_params.h>
28 
29 #include "usbaudio.h"
30 #include "helper.h"
31 #include "card.h"
32 #include "endpoint.h"
33 #include "pcm.h"
34 #include "quirks.h"
35 
36 #define EP_FLAG_RUNNING		1
37 #define EP_FLAG_STOPPING	2
38 
39 /*
40  * snd_usb_endpoint is a model that abstracts everything related to an
41  * USB endpoint and its streaming.
42  *
43  * There are functions to activate and deactivate the streaming URBs and
44  * optional callbacks to let the pcm logic handle the actual content of the
45  * packets for playback and record. Thus, the bus streaming and the audio
46  * handlers are fully decoupled.
47  *
48  * There are two different types of endpoints in audio applications.
49  *
50  * SND_USB_ENDPOINT_TYPE_DATA handles full audio data payload for both
51  * inbound and outbound traffic.
52  *
53  * SND_USB_ENDPOINT_TYPE_SYNC endpoints are for inbound traffic only and
54  * expect the payload to carry Q10.14 / Q16.16 formatted sync information
55  * (3 or 4 bytes).
56  *
57  * Each endpoint has to be configured prior to being used by calling
58  * snd_usb_endpoint_set_params().
59  *
60  * The model incorporates a reference counting, so that multiple users
61  * can call snd_usb_endpoint_start() and snd_usb_endpoint_stop(), and
62  * only the first user will effectively start the URBs, and only the last
63  * one to stop it will tear the URBs down again.
64  */
65 
66 /*
67  * convert a sampling rate into our full speed format (fs/1000 in Q16.16)
68  * this will overflow at approx 524 kHz
69  */
70 static inline unsigned get_usb_full_speed_rate(unsigned int rate)
71 {
72 	return ((rate << 13) + 62) / 125;
73 }
74 
75 /*
76  * convert a sampling rate into USB high speed format (fs/8000 in Q16.16)
77  * this will overflow at approx 4 MHz
78  */
79 static inline unsigned get_usb_high_speed_rate(unsigned int rate)
80 {
81 	return ((rate << 10) + 62) / 125;
82 }
83 
84 /*
85  * release a urb data
86  */
87 static void release_urb_ctx(struct snd_urb_ctx *u)
88 {
89 	if (u->buffer_size)
90 		usb_free_coherent(u->ep->chip->dev, u->buffer_size,
91 				  u->urb->transfer_buffer,
92 				  u->urb->transfer_dma);
93 	usb_free_urb(u->urb);
94 	u->urb = NULL;
95 }
96 
97 static const char *usb_error_string(int err)
98 {
99 	switch (err) {
100 	case -ENODEV:
101 		return "no device";
102 	case -ENOENT:
103 		return "endpoint not enabled";
104 	case -EPIPE:
105 		return "endpoint stalled";
106 	case -ENOSPC:
107 		return "not enough bandwidth";
108 	case -ESHUTDOWN:
109 		return "device disabled";
110 	case -EHOSTUNREACH:
111 		return "device suspended";
112 	case -EINVAL:
113 	case -EAGAIN:
114 	case -EFBIG:
115 	case -EMSGSIZE:
116 		return "internal error";
117 	default:
118 		return "unknown error";
119 	}
120 }
121 
122 /**
123  * snd_usb_endpoint_implicit_feedback_sink: Report endpoint usage type
124  *
125  * @ep: The snd_usb_endpoint
126  *
127  * Determine whether an endpoint is driven by an implicit feedback
128  * data endpoint source.
129  */
130 int snd_usb_endpoint_implicit_feedback_sink(struct snd_usb_endpoint *ep)
131 {
132 	return  ep->sync_master &&
133 		ep->sync_master->type == SND_USB_ENDPOINT_TYPE_DATA &&
134 		ep->type == SND_USB_ENDPOINT_TYPE_DATA &&
135 		usb_pipeout(ep->pipe);
136 }
137 
138 /*
139  * For streaming based on information derived from sync endpoints,
140  * prepare_outbound_urb_sizes() will call next_packet_size() to
141  * determine the number of samples to be sent in the next packet.
142  *
143  * For implicit feedback, next_packet_size() is unused.
144  */
145 int snd_usb_endpoint_next_packet_size(struct snd_usb_endpoint *ep)
146 {
147 	unsigned long flags;
148 	int ret;
149 
150 	if (ep->fill_max)
151 		return ep->maxframesize;
152 
153 	spin_lock_irqsave(&ep->lock, flags);
154 	ep->phase = (ep->phase & 0xffff)
155 		+ (ep->freqm << ep->datainterval);
156 	ret = min(ep->phase >> 16, ep->maxframesize);
157 	spin_unlock_irqrestore(&ep->lock, flags);
158 
159 	return ret;
160 }
161 
162 static void retire_outbound_urb(struct snd_usb_endpoint *ep,
163 				struct snd_urb_ctx *urb_ctx)
164 {
165 	if (ep->retire_data_urb)
166 		ep->retire_data_urb(ep->data_subs, urb_ctx->urb);
167 }
168 
169 static void retire_inbound_urb(struct snd_usb_endpoint *ep,
170 			       struct snd_urb_ctx *urb_ctx)
171 {
172 	struct urb *urb = urb_ctx->urb;
173 
174 	if (unlikely(ep->skip_packets > 0)) {
175 		ep->skip_packets--;
176 		return;
177 	}
178 
179 	if (ep->sync_slave)
180 		snd_usb_handle_sync_urb(ep->sync_slave, ep, urb);
181 
182 	if (ep->retire_data_urb)
183 		ep->retire_data_urb(ep->data_subs, urb);
184 }
185 
186 static void prepare_silent_urb(struct snd_usb_endpoint *ep,
187 			       struct snd_urb_ctx *ctx)
188 {
189 	struct urb *urb = ctx->urb;
190 	unsigned int offs = 0;
191 	unsigned int extra = 0;
192 	__le32 packet_length;
193 	int i;
194 
195 	/* For tx_length_quirk, put packet length at start of packet */
196 	if (ep->chip->tx_length_quirk)
197 		extra = sizeof(packet_length);
198 
199 	for (i = 0; i < ctx->packets; ++i) {
200 		unsigned int offset;
201 		unsigned int length;
202 		int counts;
203 
204 		if (ctx->packet_size[i])
205 			counts = ctx->packet_size[i];
206 		else
207 			counts = snd_usb_endpoint_next_packet_size(ep);
208 
209 		length = counts * ep->stride; /* number of silent bytes */
210 		offset = offs * ep->stride + extra * i;
211 		urb->iso_frame_desc[i].offset = offset;
212 		urb->iso_frame_desc[i].length = length + extra;
213 		if (extra) {
214 			packet_length = cpu_to_le32(length);
215 			memcpy(urb->transfer_buffer + offset,
216 			       &packet_length, sizeof(packet_length));
217 		}
218 		memset(urb->transfer_buffer + offset + extra,
219 		       ep->silence_value, length);
220 		offs += counts;
221 	}
222 
223 	urb->number_of_packets = ctx->packets;
224 	urb->transfer_buffer_length = offs * ep->stride + ctx->packets * extra;
225 }
226 
227 /*
228  * Prepare a PLAYBACK urb for submission to the bus.
229  */
230 static void prepare_outbound_urb(struct snd_usb_endpoint *ep,
231 				 struct snd_urb_ctx *ctx)
232 {
233 	struct urb *urb = ctx->urb;
234 	unsigned char *cp = urb->transfer_buffer;
235 
236 	urb->dev = ep->chip->dev; /* we need to set this at each time */
237 
238 	switch (ep->type) {
239 	case SND_USB_ENDPOINT_TYPE_DATA:
240 		if (ep->prepare_data_urb) {
241 			ep->prepare_data_urb(ep->data_subs, urb);
242 		} else {
243 			/* no data provider, so send silence */
244 			prepare_silent_urb(ep, ctx);
245 		}
246 		break;
247 
248 	case SND_USB_ENDPOINT_TYPE_SYNC:
249 		if (snd_usb_get_speed(ep->chip->dev) >= USB_SPEED_HIGH) {
250 			/*
251 			 * fill the length and offset of each urb descriptor.
252 			 * the fixed 12.13 frequency is passed as 16.16 through the pipe.
253 			 */
254 			urb->iso_frame_desc[0].length = 4;
255 			urb->iso_frame_desc[0].offset = 0;
256 			cp[0] = ep->freqn;
257 			cp[1] = ep->freqn >> 8;
258 			cp[2] = ep->freqn >> 16;
259 			cp[3] = ep->freqn >> 24;
260 		} else {
261 			/*
262 			 * fill the length and offset of each urb descriptor.
263 			 * the fixed 10.14 frequency is passed through the pipe.
264 			 */
265 			urb->iso_frame_desc[0].length = 3;
266 			urb->iso_frame_desc[0].offset = 0;
267 			cp[0] = ep->freqn >> 2;
268 			cp[1] = ep->freqn >> 10;
269 			cp[2] = ep->freqn >> 18;
270 		}
271 
272 		break;
273 	}
274 }
275 
276 /*
277  * Prepare a CAPTURE or SYNC urb for submission to the bus.
278  */
279 static inline void prepare_inbound_urb(struct snd_usb_endpoint *ep,
280 				       struct snd_urb_ctx *urb_ctx)
281 {
282 	int i, offs;
283 	struct urb *urb = urb_ctx->urb;
284 
285 	urb->dev = ep->chip->dev; /* we need to set this at each time */
286 
287 	switch (ep->type) {
288 	case SND_USB_ENDPOINT_TYPE_DATA:
289 		offs = 0;
290 		for (i = 0; i < urb_ctx->packets; i++) {
291 			urb->iso_frame_desc[i].offset = offs;
292 			urb->iso_frame_desc[i].length = ep->curpacksize;
293 			offs += ep->curpacksize;
294 		}
295 
296 		urb->transfer_buffer_length = offs;
297 		urb->number_of_packets = urb_ctx->packets;
298 		break;
299 
300 	case SND_USB_ENDPOINT_TYPE_SYNC:
301 		urb->iso_frame_desc[0].length = min(4u, ep->syncmaxsize);
302 		urb->iso_frame_desc[0].offset = 0;
303 		break;
304 	}
305 }
306 
307 /*
308  * Send output urbs that have been prepared previously. URBs are dequeued
309  * from ep->ready_playback_urbs and in case there there aren't any available
310  * or there are no packets that have been prepared, this function does
311  * nothing.
312  *
313  * The reason why the functionality of sending and preparing URBs is separated
314  * is that host controllers don't guarantee the order in which they return
315  * inbound and outbound packets to their submitters.
316  *
317  * This function is only used for implicit feedback endpoints. For endpoints
318  * driven by dedicated sync endpoints, URBs are immediately re-submitted
319  * from their completion handler.
320  */
321 static void queue_pending_output_urbs(struct snd_usb_endpoint *ep)
322 {
323 	while (test_bit(EP_FLAG_RUNNING, &ep->flags)) {
324 
325 		unsigned long flags;
326 		struct snd_usb_packet_info *uninitialized_var(packet);
327 		struct snd_urb_ctx *ctx = NULL;
328 		struct urb *urb;
329 		int err, i;
330 
331 		spin_lock_irqsave(&ep->lock, flags);
332 		if (ep->next_packet_read_pos != ep->next_packet_write_pos) {
333 			packet = ep->next_packet + ep->next_packet_read_pos;
334 			ep->next_packet_read_pos++;
335 			ep->next_packet_read_pos %= MAX_URBS;
336 
337 			/* take URB out of FIFO */
338 			if (!list_empty(&ep->ready_playback_urbs))
339 				ctx = list_first_entry(&ep->ready_playback_urbs,
340 					       struct snd_urb_ctx, ready_list);
341 		}
342 		spin_unlock_irqrestore(&ep->lock, flags);
343 
344 		if (ctx == NULL)
345 			return;
346 
347 		list_del_init(&ctx->ready_list);
348 		urb = ctx->urb;
349 
350 		/* copy over the length information */
351 		for (i = 0; i < packet->packets; i++)
352 			ctx->packet_size[i] = packet->packet_size[i];
353 
354 		/* call the data handler to fill in playback data */
355 		prepare_outbound_urb(ep, ctx);
356 
357 		err = usb_submit_urb(ctx->urb, GFP_ATOMIC);
358 		if (err < 0)
359 			usb_audio_err(ep->chip,
360 				"Unable to submit urb #%d: %d (urb %p)\n",
361 				ctx->index, err, ctx->urb);
362 		else
363 			set_bit(ctx->index, &ep->active_mask);
364 	}
365 }
366 
367 /*
368  * complete callback for urbs
369  */
370 static void snd_complete_urb(struct urb *urb)
371 {
372 	struct snd_urb_ctx *ctx = urb->context;
373 	struct snd_usb_endpoint *ep = ctx->ep;
374 	struct snd_pcm_substream *substream;
375 	unsigned long flags;
376 	int err;
377 
378 	if (unlikely(urb->status == -ENOENT ||		/* unlinked */
379 		     urb->status == -ENODEV ||		/* device removed */
380 		     urb->status == -ECONNRESET ||	/* unlinked */
381 		     urb->status == -ESHUTDOWN))	/* device disabled */
382 		goto exit_clear;
383 	/* device disconnected */
384 	if (unlikely(atomic_read(&ep->chip->shutdown)))
385 		goto exit_clear;
386 
387 	if (usb_pipeout(ep->pipe)) {
388 		retire_outbound_urb(ep, ctx);
389 		/* can be stopped during retire callback */
390 		if (unlikely(!test_bit(EP_FLAG_RUNNING, &ep->flags)))
391 			goto exit_clear;
392 
393 		if (snd_usb_endpoint_implicit_feedback_sink(ep)) {
394 			spin_lock_irqsave(&ep->lock, flags);
395 			list_add_tail(&ctx->ready_list, &ep->ready_playback_urbs);
396 			spin_unlock_irqrestore(&ep->lock, flags);
397 			queue_pending_output_urbs(ep);
398 
399 			goto exit_clear;
400 		}
401 
402 		prepare_outbound_urb(ep, ctx);
403 	} else {
404 		retire_inbound_urb(ep, ctx);
405 		/* can be stopped during retire callback */
406 		if (unlikely(!test_bit(EP_FLAG_RUNNING, &ep->flags)))
407 			goto exit_clear;
408 
409 		prepare_inbound_urb(ep, ctx);
410 	}
411 
412 	err = usb_submit_urb(urb, GFP_ATOMIC);
413 	if (err == 0)
414 		return;
415 
416 	usb_audio_err(ep->chip, "cannot submit urb (err = %d)\n", err);
417 	if (ep->data_subs && ep->data_subs->pcm_substream) {
418 		substream = ep->data_subs->pcm_substream;
419 		snd_pcm_stop_xrun(substream);
420 	}
421 
422 exit_clear:
423 	clear_bit(ctx->index, &ep->active_mask);
424 }
425 
426 /**
427  * snd_usb_add_endpoint: Add an endpoint to an USB audio chip
428  *
429  * @chip: The chip
430  * @alts: The USB host interface
431  * @ep_num: The number of the endpoint to use
432  * @direction: SNDRV_PCM_STREAM_PLAYBACK or SNDRV_PCM_STREAM_CAPTURE
433  * @type: SND_USB_ENDPOINT_TYPE_DATA or SND_USB_ENDPOINT_TYPE_SYNC
434  *
435  * If the requested endpoint has not been added to the given chip before,
436  * a new instance is created. Otherwise, a pointer to the previoulsy
437  * created instance is returned. In case of any error, NULL is returned.
438  *
439  * New endpoints will be added to chip->ep_list and must be freed by
440  * calling snd_usb_endpoint_free().
441  */
442 struct snd_usb_endpoint *snd_usb_add_endpoint(struct snd_usb_audio *chip,
443 					      struct usb_host_interface *alts,
444 					      int ep_num, int direction, int type)
445 {
446 	struct snd_usb_endpoint *ep;
447 	int is_playback = direction == SNDRV_PCM_STREAM_PLAYBACK;
448 
449 	if (WARN_ON(!alts))
450 		return NULL;
451 
452 	mutex_lock(&chip->mutex);
453 
454 	list_for_each_entry(ep, &chip->ep_list, list) {
455 		if (ep->ep_num == ep_num &&
456 		    ep->iface == alts->desc.bInterfaceNumber &&
457 		    ep->altsetting == alts->desc.bAlternateSetting) {
458 			usb_audio_dbg(ep->chip,
459 				      "Re-using EP %x in iface %d,%d @%p\n",
460 					ep_num, ep->iface, ep->altsetting, ep);
461 			goto __exit_unlock;
462 		}
463 	}
464 
465 	usb_audio_dbg(chip, "Creating new %s %s endpoint #%x\n",
466 		    is_playback ? "playback" : "capture",
467 		    type == SND_USB_ENDPOINT_TYPE_DATA ? "data" : "sync",
468 		    ep_num);
469 
470 	ep = kzalloc(sizeof(*ep), GFP_KERNEL);
471 	if (!ep)
472 		goto __exit_unlock;
473 
474 	ep->chip = chip;
475 	spin_lock_init(&ep->lock);
476 	ep->type = type;
477 	ep->ep_num = ep_num;
478 	ep->iface = alts->desc.bInterfaceNumber;
479 	ep->altsetting = alts->desc.bAlternateSetting;
480 	INIT_LIST_HEAD(&ep->ready_playback_urbs);
481 	ep_num &= USB_ENDPOINT_NUMBER_MASK;
482 
483 	if (is_playback)
484 		ep->pipe = usb_sndisocpipe(chip->dev, ep_num);
485 	else
486 		ep->pipe = usb_rcvisocpipe(chip->dev, ep_num);
487 
488 	if (type == SND_USB_ENDPOINT_TYPE_SYNC) {
489 		if (get_endpoint(alts, 1)->bLength >= USB_DT_ENDPOINT_AUDIO_SIZE &&
490 		    get_endpoint(alts, 1)->bRefresh >= 1 &&
491 		    get_endpoint(alts, 1)->bRefresh <= 9)
492 			ep->syncinterval = get_endpoint(alts, 1)->bRefresh;
493 		else if (snd_usb_get_speed(chip->dev) == USB_SPEED_FULL)
494 			ep->syncinterval = 1;
495 		else if (get_endpoint(alts, 1)->bInterval >= 1 &&
496 			 get_endpoint(alts, 1)->bInterval <= 16)
497 			ep->syncinterval = get_endpoint(alts, 1)->bInterval - 1;
498 		else
499 			ep->syncinterval = 3;
500 
501 		ep->syncmaxsize = le16_to_cpu(get_endpoint(alts, 1)->wMaxPacketSize);
502 
503 		if (chip->usb_id == USB_ID(0x0644, 0x8038) /* TEAC UD-H01 */ &&
504 		    ep->syncmaxsize == 4)
505 			ep->udh01_fb_quirk = 1;
506 	}
507 
508 	list_add_tail(&ep->list, &chip->ep_list);
509 
510 __exit_unlock:
511 	mutex_unlock(&chip->mutex);
512 
513 	return ep;
514 }
515 
516 /*
517  *  wait until all urbs are processed.
518  */
519 static int wait_clear_urbs(struct snd_usb_endpoint *ep)
520 {
521 	unsigned long end_time = jiffies + msecs_to_jiffies(1000);
522 	int alive;
523 
524 	do {
525 		alive = bitmap_weight(&ep->active_mask, ep->nurbs);
526 		if (!alive)
527 			break;
528 
529 		schedule_timeout_uninterruptible(1);
530 	} while (time_before(jiffies, end_time));
531 
532 	if (alive)
533 		usb_audio_err(ep->chip,
534 			"timeout: still %d active urbs on EP #%x\n",
535 			alive, ep->ep_num);
536 	clear_bit(EP_FLAG_STOPPING, &ep->flags);
537 
538 	return 0;
539 }
540 
541 /* sync the pending stop operation;
542  * this function itself doesn't trigger the stop operation
543  */
544 void snd_usb_endpoint_sync_pending_stop(struct snd_usb_endpoint *ep)
545 {
546 	if (ep && test_bit(EP_FLAG_STOPPING, &ep->flags))
547 		wait_clear_urbs(ep);
548 }
549 
550 /*
551  * unlink active urbs.
552  */
553 static int deactivate_urbs(struct snd_usb_endpoint *ep, bool force)
554 {
555 	unsigned int i;
556 
557 	if (!force && atomic_read(&ep->chip->shutdown)) /* to be sure... */
558 		return -EBADFD;
559 
560 	clear_bit(EP_FLAG_RUNNING, &ep->flags);
561 
562 	INIT_LIST_HEAD(&ep->ready_playback_urbs);
563 	ep->next_packet_read_pos = 0;
564 	ep->next_packet_write_pos = 0;
565 
566 	for (i = 0; i < ep->nurbs; i++) {
567 		if (test_bit(i, &ep->active_mask)) {
568 			if (!test_and_set_bit(i, &ep->unlink_mask)) {
569 				struct urb *u = ep->urb[i].urb;
570 				usb_unlink_urb(u);
571 			}
572 		}
573 	}
574 
575 	return 0;
576 }
577 
578 /*
579  * release an endpoint's urbs
580  */
581 static void release_urbs(struct snd_usb_endpoint *ep, int force)
582 {
583 	int i;
584 
585 	/* route incoming urbs to nirvana */
586 	ep->retire_data_urb = NULL;
587 	ep->prepare_data_urb = NULL;
588 
589 	/* stop urbs */
590 	deactivate_urbs(ep, force);
591 	wait_clear_urbs(ep);
592 
593 	for (i = 0; i < ep->nurbs; i++)
594 		release_urb_ctx(&ep->urb[i]);
595 
596 	if (ep->syncbuf)
597 		usb_free_coherent(ep->chip->dev, SYNC_URBS * 4,
598 				  ep->syncbuf, ep->sync_dma);
599 
600 	ep->syncbuf = NULL;
601 	ep->nurbs = 0;
602 }
603 
604 /*
605  * configure a data endpoint
606  */
607 static int data_ep_set_params(struct snd_usb_endpoint *ep,
608 			      snd_pcm_format_t pcm_format,
609 			      unsigned int channels,
610 			      unsigned int period_bytes,
611 			      unsigned int frames_per_period,
612 			      unsigned int periods_per_buffer,
613 			      struct audioformat *fmt,
614 			      struct snd_usb_endpoint *sync_ep)
615 {
616 	unsigned int maxsize, minsize, packs_per_ms, max_packs_per_urb;
617 	unsigned int max_packs_per_period, urbs_per_period, urb_packs;
618 	unsigned int max_urbs, i;
619 	int frame_bits = snd_pcm_format_physical_width(pcm_format) * channels;
620 	int tx_length_quirk = (ep->chip->tx_length_quirk &&
621 			       usb_pipeout(ep->pipe));
622 
623 	if (pcm_format == SNDRV_PCM_FORMAT_DSD_U16_LE && fmt->dsd_dop) {
624 		/*
625 		 * When operating in DSD DOP mode, the size of a sample frame
626 		 * in hardware differs from the actual physical format width
627 		 * because we need to make room for the DOP markers.
628 		 */
629 		frame_bits += channels << 3;
630 	}
631 
632 	ep->datainterval = fmt->datainterval;
633 	ep->stride = frame_bits >> 3;
634 	ep->silence_value = pcm_format == SNDRV_PCM_FORMAT_U8 ? 0x80 : 0;
635 
636 	/* assume max. frequency is 25% higher than nominal */
637 	ep->freqmax = ep->freqn + (ep->freqn >> 2);
638 	/* Round up freqmax to nearest integer in order to calculate maximum
639 	 * packet size, which must represent a whole number of frames.
640 	 * This is accomplished by adding 0x0.ffff before converting the
641 	 * Q16.16 format into integer.
642 	 * In order to accurately calculate the maximum packet size when
643 	 * the data interval is more than 1 (i.e. ep->datainterval > 0),
644 	 * multiply by the data interval prior to rounding. For instance,
645 	 * a freqmax of 41 kHz will result in a max packet size of 6 (5.125)
646 	 * frames with a data interval of 1, but 11 (10.25) frames with a
647 	 * data interval of 2.
648 	 * (ep->freqmax << ep->datainterval overflows at 8.192 MHz for the
649 	 * maximum datainterval value of 3, at USB full speed, higher for
650 	 * USB high speed, noting that ep->freqmax is in units of
651 	 * frames per packet in Q16.16 format.)
652 	 */
653 	maxsize = (((ep->freqmax << ep->datainterval) + 0xffff) >> 16) *
654 			 (frame_bits >> 3);
655 	if (tx_length_quirk)
656 		maxsize += sizeof(__le32); /* Space for length descriptor */
657 	/* but wMaxPacketSize might reduce this */
658 	if (ep->maxpacksize && ep->maxpacksize < maxsize) {
659 		/* whatever fits into a max. size packet */
660 		unsigned int data_maxsize = maxsize = ep->maxpacksize;
661 
662 		if (tx_length_quirk)
663 			/* Need to remove the length descriptor to calc freq */
664 			data_maxsize -= sizeof(__le32);
665 		ep->freqmax = (data_maxsize / (frame_bits >> 3))
666 				<< (16 - ep->datainterval);
667 	}
668 
669 	if (ep->fill_max)
670 		ep->curpacksize = ep->maxpacksize;
671 	else
672 		ep->curpacksize = maxsize;
673 
674 	if (snd_usb_get_speed(ep->chip->dev) != USB_SPEED_FULL) {
675 		packs_per_ms = 8 >> ep->datainterval;
676 		max_packs_per_urb = MAX_PACKS_HS;
677 	} else {
678 		packs_per_ms = 1;
679 		max_packs_per_urb = MAX_PACKS;
680 	}
681 	if (sync_ep && !snd_usb_endpoint_implicit_feedback_sink(ep))
682 		max_packs_per_urb = min(max_packs_per_urb,
683 					1U << sync_ep->syncinterval);
684 	max_packs_per_urb = max(1u, max_packs_per_urb >> ep->datainterval);
685 
686 	/*
687 	 * Capture endpoints need to use small URBs because there's no way
688 	 * to tell in advance where the next period will end, and we don't
689 	 * want the next URB to complete much after the period ends.
690 	 *
691 	 * Playback endpoints with implicit sync much use the same parameters
692 	 * as their corresponding capture endpoint.
693 	 */
694 	if (usb_pipein(ep->pipe) ||
695 			snd_usb_endpoint_implicit_feedback_sink(ep)) {
696 
697 		urb_packs = packs_per_ms;
698 		/*
699 		 * Wireless devices can poll at a max rate of once per 4ms.
700 		 * For dataintervals less than 5, increase the packet count to
701 		 * allow the host controller to use bursting to fill in the
702 		 * gaps.
703 		 */
704 		if (snd_usb_get_speed(ep->chip->dev) == USB_SPEED_WIRELESS) {
705 			int interval = ep->datainterval;
706 			while (interval < 5) {
707 				urb_packs <<= 1;
708 				++interval;
709 			}
710 		}
711 		/* make capture URBs <= 1 ms and smaller than a period */
712 		urb_packs = min(max_packs_per_urb, urb_packs);
713 		while (urb_packs > 1 && urb_packs * maxsize >= period_bytes)
714 			urb_packs >>= 1;
715 		ep->nurbs = MAX_URBS;
716 
717 	/*
718 	 * Playback endpoints without implicit sync are adjusted so that
719 	 * a period fits as evenly as possible in the smallest number of
720 	 * URBs.  The total number of URBs is adjusted to the size of the
721 	 * ALSA buffer, subject to the MAX_URBS and MAX_QUEUE limits.
722 	 */
723 	} else {
724 		/* determine how small a packet can be */
725 		minsize = (ep->freqn >> (16 - ep->datainterval)) *
726 				(frame_bits >> 3);
727 		/* with sync from device, assume it can be 12% lower */
728 		if (sync_ep)
729 			minsize -= minsize >> 3;
730 		minsize = max(minsize, 1u);
731 
732 		/* how many packets will contain an entire ALSA period? */
733 		max_packs_per_period = DIV_ROUND_UP(period_bytes, minsize);
734 
735 		/* how many URBs will contain a period? */
736 		urbs_per_period = DIV_ROUND_UP(max_packs_per_period,
737 				max_packs_per_urb);
738 		/* how many packets are needed in each URB? */
739 		urb_packs = DIV_ROUND_UP(max_packs_per_period, urbs_per_period);
740 
741 		/* limit the number of frames in a single URB */
742 		ep->max_urb_frames = DIV_ROUND_UP(frames_per_period,
743 					urbs_per_period);
744 
745 		/* try to use enough URBs to contain an entire ALSA buffer */
746 		max_urbs = min((unsigned) MAX_URBS,
747 				MAX_QUEUE * packs_per_ms / urb_packs);
748 		ep->nurbs = min(max_urbs, urbs_per_period * periods_per_buffer);
749 	}
750 
751 	/* allocate and initialize data urbs */
752 	for (i = 0; i < ep->nurbs; i++) {
753 		struct snd_urb_ctx *u = &ep->urb[i];
754 		u->index = i;
755 		u->ep = ep;
756 		u->packets = urb_packs;
757 		u->buffer_size = maxsize * u->packets;
758 
759 		if (fmt->fmt_type == UAC_FORMAT_TYPE_II)
760 			u->packets++; /* for transfer delimiter */
761 		u->urb = usb_alloc_urb(u->packets, GFP_KERNEL);
762 		if (!u->urb)
763 			goto out_of_memory;
764 
765 		u->urb->transfer_buffer =
766 			usb_alloc_coherent(ep->chip->dev, u->buffer_size,
767 					   GFP_KERNEL, &u->urb->transfer_dma);
768 		if (!u->urb->transfer_buffer)
769 			goto out_of_memory;
770 		u->urb->pipe = ep->pipe;
771 		u->urb->transfer_flags = URB_NO_TRANSFER_DMA_MAP;
772 		u->urb->interval = 1 << ep->datainterval;
773 		u->urb->context = u;
774 		u->urb->complete = snd_complete_urb;
775 		INIT_LIST_HEAD(&u->ready_list);
776 	}
777 
778 	return 0;
779 
780 out_of_memory:
781 	release_urbs(ep, 0);
782 	return -ENOMEM;
783 }
784 
785 /*
786  * configure a sync endpoint
787  */
788 static int sync_ep_set_params(struct snd_usb_endpoint *ep)
789 {
790 	int i;
791 
792 	ep->syncbuf = usb_alloc_coherent(ep->chip->dev, SYNC_URBS * 4,
793 					 GFP_KERNEL, &ep->sync_dma);
794 	if (!ep->syncbuf)
795 		return -ENOMEM;
796 
797 	for (i = 0; i < SYNC_URBS; i++) {
798 		struct snd_urb_ctx *u = &ep->urb[i];
799 		u->index = i;
800 		u->ep = ep;
801 		u->packets = 1;
802 		u->urb = usb_alloc_urb(1, GFP_KERNEL);
803 		if (!u->urb)
804 			goto out_of_memory;
805 		u->urb->transfer_buffer = ep->syncbuf + i * 4;
806 		u->urb->transfer_dma = ep->sync_dma + i * 4;
807 		u->urb->transfer_buffer_length = 4;
808 		u->urb->pipe = ep->pipe;
809 		u->urb->transfer_flags = URB_NO_TRANSFER_DMA_MAP;
810 		u->urb->number_of_packets = 1;
811 		u->urb->interval = 1 << ep->syncinterval;
812 		u->urb->context = u;
813 		u->urb->complete = snd_complete_urb;
814 	}
815 
816 	ep->nurbs = SYNC_URBS;
817 
818 	return 0;
819 
820 out_of_memory:
821 	release_urbs(ep, 0);
822 	return -ENOMEM;
823 }
824 
825 /**
826  * snd_usb_endpoint_set_params: configure an snd_usb_endpoint
827  *
828  * @ep: the snd_usb_endpoint to configure
829  * @pcm_format: the audio fomat.
830  * @channels: the number of audio channels.
831  * @period_bytes: the number of bytes in one alsa period.
832  * @period_frames: the number of frames in one alsa period.
833  * @buffer_periods: the number of periods in one alsa buffer.
834  * @rate: the frame rate.
835  * @fmt: the USB audio format information
836  * @sync_ep: the sync endpoint to use, if any
837  *
838  * Determine the number of URBs to be used on this endpoint.
839  * An endpoint must be configured before it can be started.
840  * An endpoint that is already running can not be reconfigured.
841  */
842 int snd_usb_endpoint_set_params(struct snd_usb_endpoint *ep,
843 				snd_pcm_format_t pcm_format,
844 				unsigned int channels,
845 				unsigned int period_bytes,
846 				unsigned int period_frames,
847 				unsigned int buffer_periods,
848 				unsigned int rate,
849 				struct audioformat *fmt,
850 				struct snd_usb_endpoint *sync_ep)
851 {
852 	int err;
853 
854 	if (ep->use_count != 0) {
855 		usb_audio_warn(ep->chip,
856 			 "Unable to change format on ep #%x: already in use\n",
857 			 ep->ep_num);
858 		return -EBUSY;
859 	}
860 
861 	/* release old buffers, if any */
862 	release_urbs(ep, 0);
863 
864 	ep->datainterval = fmt->datainterval;
865 	ep->maxpacksize = fmt->maxpacksize;
866 	ep->fill_max = !!(fmt->attributes & UAC_EP_CS_ATTR_FILL_MAX);
867 
868 	if (snd_usb_get_speed(ep->chip->dev) == USB_SPEED_FULL)
869 		ep->freqn = get_usb_full_speed_rate(rate);
870 	else
871 		ep->freqn = get_usb_high_speed_rate(rate);
872 
873 	/* calculate the frequency in 16.16 format */
874 	ep->freqm = ep->freqn;
875 	ep->freqshift = INT_MIN;
876 
877 	ep->phase = 0;
878 
879 	switch (ep->type) {
880 	case  SND_USB_ENDPOINT_TYPE_DATA:
881 		err = data_ep_set_params(ep, pcm_format, channels,
882 					 period_bytes, period_frames,
883 					 buffer_periods, fmt, sync_ep);
884 		break;
885 	case  SND_USB_ENDPOINT_TYPE_SYNC:
886 		err = sync_ep_set_params(ep);
887 		break;
888 	default:
889 		err = -EINVAL;
890 	}
891 
892 	usb_audio_dbg(ep->chip,
893 		"Setting params for ep #%x (type %d, %d urbs), ret=%d\n",
894 		ep->ep_num, ep->type, ep->nurbs, err);
895 
896 	return err;
897 }
898 
899 /**
900  * snd_usb_endpoint_start: start an snd_usb_endpoint
901  *
902  * @ep:		the endpoint to start
903  * @can_sleep:	flag indicating whether the operation is executed in
904  * 		non-atomic context
905  *
906  * A call to this function will increment the use count of the endpoint.
907  * In case it is not already running, the URBs for this endpoint will be
908  * submitted. Otherwise, this function does nothing.
909  *
910  * Must be balanced to calls of snd_usb_endpoint_stop().
911  *
912  * Returns an error if the URB submission failed, 0 in all other cases.
913  */
914 int snd_usb_endpoint_start(struct snd_usb_endpoint *ep, bool can_sleep)
915 {
916 	int err;
917 	unsigned int i;
918 
919 	if (atomic_read(&ep->chip->shutdown))
920 		return -EBADFD;
921 
922 	/* already running? */
923 	if (++ep->use_count != 1)
924 		return 0;
925 
926 	/* just to be sure */
927 	deactivate_urbs(ep, false);
928 	if (can_sleep)
929 		wait_clear_urbs(ep);
930 
931 	ep->active_mask = 0;
932 	ep->unlink_mask = 0;
933 	ep->phase = 0;
934 
935 	snd_usb_endpoint_start_quirk(ep);
936 
937 	/*
938 	 * If this endpoint has a data endpoint as implicit feedback source,
939 	 * don't start the urbs here. Instead, mark them all as available,
940 	 * wait for the record urbs to return and queue the playback urbs
941 	 * from that context.
942 	 */
943 
944 	set_bit(EP_FLAG_RUNNING, &ep->flags);
945 
946 	if (snd_usb_endpoint_implicit_feedback_sink(ep)) {
947 		for (i = 0; i < ep->nurbs; i++) {
948 			struct snd_urb_ctx *ctx = ep->urb + i;
949 			list_add_tail(&ctx->ready_list, &ep->ready_playback_urbs);
950 		}
951 
952 		return 0;
953 	}
954 
955 	for (i = 0; i < ep->nurbs; i++) {
956 		struct urb *urb = ep->urb[i].urb;
957 
958 		if (snd_BUG_ON(!urb))
959 			goto __error;
960 
961 		if (usb_pipeout(ep->pipe)) {
962 			prepare_outbound_urb(ep, urb->context);
963 		} else {
964 			prepare_inbound_urb(ep, urb->context);
965 		}
966 
967 		err = usb_submit_urb(urb, GFP_ATOMIC);
968 		if (err < 0) {
969 			usb_audio_err(ep->chip,
970 				"cannot submit urb %d, error %d: %s\n",
971 				i, err, usb_error_string(err));
972 			goto __error;
973 		}
974 		set_bit(i, &ep->active_mask);
975 	}
976 
977 	return 0;
978 
979 __error:
980 	clear_bit(EP_FLAG_RUNNING, &ep->flags);
981 	ep->use_count--;
982 	deactivate_urbs(ep, false);
983 	return -EPIPE;
984 }
985 
986 /**
987  * snd_usb_endpoint_stop: stop an snd_usb_endpoint
988  *
989  * @ep: the endpoint to stop (may be NULL)
990  *
991  * A call to this function will decrement the use count of the endpoint.
992  * In case the last user has requested the endpoint stop, the URBs will
993  * actually be deactivated.
994  *
995  * Must be balanced to calls of snd_usb_endpoint_start().
996  *
997  * The caller needs to synchronize the pending stop operation via
998  * snd_usb_endpoint_sync_pending_stop().
999  */
1000 void snd_usb_endpoint_stop(struct snd_usb_endpoint *ep)
1001 {
1002 	if (!ep)
1003 		return;
1004 
1005 	if (snd_BUG_ON(ep->use_count == 0))
1006 		return;
1007 
1008 	if (--ep->use_count == 0) {
1009 		deactivate_urbs(ep, false);
1010 		ep->data_subs = NULL;
1011 		ep->sync_slave = NULL;
1012 		ep->retire_data_urb = NULL;
1013 		ep->prepare_data_urb = NULL;
1014 		set_bit(EP_FLAG_STOPPING, &ep->flags);
1015 	}
1016 }
1017 
1018 /**
1019  * snd_usb_endpoint_deactivate: deactivate an snd_usb_endpoint
1020  *
1021  * @ep: the endpoint to deactivate
1022  *
1023  * If the endpoint is not currently in use, this functions will
1024  * deactivate its associated URBs.
1025  *
1026  * In case of any active users, this functions does nothing.
1027  */
1028 void snd_usb_endpoint_deactivate(struct snd_usb_endpoint *ep)
1029 {
1030 	if (!ep)
1031 		return;
1032 
1033 	if (ep->use_count != 0)
1034 		return;
1035 
1036 	deactivate_urbs(ep, true);
1037 	wait_clear_urbs(ep);
1038 }
1039 
1040 /**
1041  * snd_usb_endpoint_release: Tear down an snd_usb_endpoint
1042  *
1043  * @ep: the endpoint to release
1044  *
1045  * This function does not care for the endpoint's use count but will tear
1046  * down all the streaming URBs immediately.
1047  */
1048 void snd_usb_endpoint_release(struct snd_usb_endpoint *ep)
1049 {
1050 	release_urbs(ep, 1);
1051 }
1052 
1053 /**
1054  * snd_usb_endpoint_free: Free the resources of an snd_usb_endpoint
1055  *
1056  * @ep: the endpoint to free
1057  *
1058  * This free all resources of the given ep.
1059  */
1060 void snd_usb_endpoint_free(struct snd_usb_endpoint *ep)
1061 {
1062 	kfree(ep);
1063 }
1064 
1065 /**
1066  * snd_usb_handle_sync_urb: parse an USB sync packet
1067  *
1068  * @ep: the endpoint to handle the packet
1069  * @sender: the sending endpoint
1070  * @urb: the received packet
1071  *
1072  * This function is called from the context of an endpoint that received
1073  * the packet and is used to let another endpoint object handle the payload.
1074  */
1075 void snd_usb_handle_sync_urb(struct snd_usb_endpoint *ep,
1076 			     struct snd_usb_endpoint *sender,
1077 			     const struct urb *urb)
1078 {
1079 	int shift;
1080 	unsigned int f;
1081 	unsigned long flags;
1082 
1083 	snd_BUG_ON(ep == sender);
1084 
1085 	/*
1086 	 * In case the endpoint is operating in implicit feedback mode, prepare
1087 	 * a new outbound URB that has the same layout as the received packet
1088 	 * and add it to the list of pending urbs. queue_pending_output_urbs()
1089 	 * will take care of them later.
1090 	 */
1091 	if (snd_usb_endpoint_implicit_feedback_sink(ep) &&
1092 	    ep->use_count != 0) {
1093 
1094 		/* implicit feedback case */
1095 		int i, bytes = 0;
1096 		struct snd_urb_ctx *in_ctx;
1097 		struct snd_usb_packet_info *out_packet;
1098 
1099 		in_ctx = urb->context;
1100 
1101 		/* Count overall packet size */
1102 		for (i = 0; i < in_ctx->packets; i++)
1103 			if (urb->iso_frame_desc[i].status == 0)
1104 				bytes += urb->iso_frame_desc[i].actual_length;
1105 
1106 		/*
1107 		 * skip empty packets. At least M-Audio's Fast Track Ultra stops
1108 		 * streaming once it received a 0-byte OUT URB
1109 		 */
1110 		if (bytes == 0)
1111 			return;
1112 
1113 		spin_lock_irqsave(&ep->lock, flags);
1114 		out_packet = ep->next_packet + ep->next_packet_write_pos;
1115 
1116 		/*
1117 		 * Iterate through the inbound packet and prepare the lengths
1118 		 * for the output packet. The OUT packet we are about to send
1119 		 * will have the same amount of payload bytes per stride as the
1120 		 * IN packet we just received. Since the actual size is scaled
1121 		 * by the stride, use the sender stride to calculate the length
1122 		 * in case the number of channels differ between the implicitly
1123 		 * fed-back endpoint and the synchronizing endpoint.
1124 		 */
1125 
1126 		out_packet->packets = in_ctx->packets;
1127 		for (i = 0; i < in_ctx->packets; i++) {
1128 			if (urb->iso_frame_desc[i].status == 0)
1129 				out_packet->packet_size[i] =
1130 					urb->iso_frame_desc[i].actual_length / sender->stride;
1131 			else
1132 				out_packet->packet_size[i] = 0;
1133 		}
1134 
1135 		ep->next_packet_write_pos++;
1136 		ep->next_packet_write_pos %= MAX_URBS;
1137 		spin_unlock_irqrestore(&ep->lock, flags);
1138 		queue_pending_output_urbs(ep);
1139 
1140 		return;
1141 	}
1142 
1143 	/*
1144 	 * process after playback sync complete
1145 	 *
1146 	 * Full speed devices report feedback values in 10.14 format as samples
1147 	 * per frame, high speed devices in 16.16 format as samples per
1148 	 * microframe.
1149 	 *
1150 	 * Because the Audio Class 1 spec was written before USB 2.0, many high
1151 	 * speed devices use a wrong interpretation, some others use an
1152 	 * entirely different format.
1153 	 *
1154 	 * Therefore, we cannot predict what format any particular device uses
1155 	 * and must detect it automatically.
1156 	 */
1157 
1158 	if (urb->iso_frame_desc[0].status != 0 ||
1159 	    urb->iso_frame_desc[0].actual_length < 3)
1160 		return;
1161 
1162 	f = le32_to_cpup(urb->transfer_buffer);
1163 	if (urb->iso_frame_desc[0].actual_length == 3)
1164 		f &= 0x00ffffff;
1165 	else
1166 		f &= 0x0fffffff;
1167 
1168 	if (f == 0)
1169 		return;
1170 
1171 	if (unlikely(sender->udh01_fb_quirk)) {
1172 		/*
1173 		 * The TEAC UD-H01 firmware sometimes changes the feedback value
1174 		 * by +/- 0x1.0000.
1175 		 */
1176 		if (f < ep->freqn - 0x8000)
1177 			f += 0x10000;
1178 		else if (f > ep->freqn + 0x8000)
1179 			f -= 0x10000;
1180 	} else if (unlikely(ep->freqshift == INT_MIN)) {
1181 		/*
1182 		 * The first time we see a feedback value, determine its format
1183 		 * by shifting it left or right until it matches the nominal
1184 		 * frequency value.  This assumes that the feedback does not
1185 		 * differ from the nominal value more than +50% or -25%.
1186 		 */
1187 		shift = 0;
1188 		while (f < ep->freqn - ep->freqn / 4) {
1189 			f <<= 1;
1190 			shift++;
1191 		}
1192 		while (f > ep->freqn + ep->freqn / 2) {
1193 			f >>= 1;
1194 			shift--;
1195 		}
1196 		ep->freqshift = shift;
1197 	} else if (ep->freqshift >= 0)
1198 		f <<= ep->freqshift;
1199 	else
1200 		f >>= -ep->freqshift;
1201 
1202 	if (likely(f >= ep->freqn - ep->freqn / 8 && f <= ep->freqmax)) {
1203 		/*
1204 		 * If the frequency looks valid, set it.
1205 		 * This value is referred to in prepare_playback_urb().
1206 		 */
1207 		spin_lock_irqsave(&ep->lock, flags);
1208 		ep->freqm = f;
1209 		spin_unlock_irqrestore(&ep->lock, flags);
1210 	} else {
1211 		/*
1212 		 * Out of range; maybe the shift value is wrong.
1213 		 * Reset it so that we autodetect again the next time.
1214 		 */
1215 		ep->freqshift = INT_MIN;
1216 	}
1217 }
1218 
1219