xref: /linux/sound/usb/endpoint.c (revision 0889d07f3e4b171c453b2aaf2b257f9074cdf624)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  */
4 
5 #include <linux/gfp.h>
6 #include <linux/init.h>
7 #include <linux/ratelimit.h>
8 #include <linux/usb.h>
9 #include <linux/usb/audio.h>
10 #include <linux/slab.h>
11 
12 #include <sound/core.h>
13 #include <sound/pcm.h>
14 #include <sound/pcm_params.h>
15 
16 #include "usbaudio.h"
17 #include "helper.h"
18 #include "card.h"
19 #include "endpoint.h"
20 #include "pcm.h"
21 #include "quirks.h"
22 
23 #define EP_FLAG_RUNNING		1
24 #define EP_FLAG_STOPPING	2
25 
26 /*
27  * snd_usb_endpoint is a model that abstracts everything related to an
28  * USB endpoint and its streaming.
29  *
30  * There are functions to activate and deactivate the streaming URBs and
31  * optional callbacks to let the pcm logic handle the actual content of the
32  * packets for playback and record. Thus, the bus streaming and the audio
33  * handlers are fully decoupled.
34  *
35  * There are two different types of endpoints in audio applications.
36  *
37  * SND_USB_ENDPOINT_TYPE_DATA handles full audio data payload for both
38  * inbound and outbound traffic.
39  *
40  * SND_USB_ENDPOINT_TYPE_SYNC endpoints are for inbound traffic only and
41  * expect the payload to carry Q10.14 / Q16.16 formatted sync information
42  * (3 or 4 bytes).
43  *
44  * Each endpoint has to be configured prior to being used by calling
45  * snd_usb_endpoint_set_params().
46  *
47  * The model incorporates a reference counting, so that multiple users
48  * can call snd_usb_endpoint_start() and snd_usb_endpoint_stop(), and
49  * only the first user will effectively start the URBs, and only the last
50  * one to stop it will tear the URBs down again.
51  */
52 
53 /*
54  * convert a sampling rate into our full speed format (fs/1000 in Q16.16)
55  * this will overflow at approx 524 kHz
56  */
57 static inline unsigned get_usb_full_speed_rate(unsigned int rate)
58 {
59 	return ((rate << 13) + 62) / 125;
60 }
61 
62 /*
63  * convert a sampling rate into USB high speed format (fs/8000 in Q16.16)
64  * this will overflow at approx 4 MHz
65  */
66 static inline unsigned get_usb_high_speed_rate(unsigned int rate)
67 {
68 	return ((rate << 10) + 62) / 125;
69 }
70 
71 /*
72  * release a urb data
73  */
74 static void release_urb_ctx(struct snd_urb_ctx *u)
75 {
76 	if (u->buffer_size)
77 		usb_free_coherent(u->ep->chip->dev, u->buffer_size,
78 				  u->urb->transfer_buffer,
79 				  u->urb->transfer_dma);
80 	usb_free_urb(u->urb);
81 	u->urb = NULL;
82 }
83 
84 static const char *usb_error_string(int err)
85 {
86 	switch (err) {
87 	case -ENODEV:
88 		return "no device";
89 	case -ENOENT:
90 		return "endpoint not enabled";
91 	case -EPIPE:
92 		return "endpoint stalled";
93 	case -ENOSPC:
94 		return "not enough bandwidth";
95 	case -ESHUTDOWN:
96 		return "device disabled";
97 	case -EHOSTUNREACH:
98 		return "device suspended";
99 	case -EINVAL:
100 	case -EAGAIN:
101 	case -EFBIG:
102 	case -EMSGSIZE:
103 		return "internal error";
104 	default:
105 		return "unknown error";
106 	}
107 }
108 
109 /**
110  * snd_usb_endpoint_implicit_feedback_sink: Report endpoint usage type
111  *
112  * @ep: The snd_usb_endpoint
113  *
114  * Determine whether an endpoint is driven by an implicit feedback
115  * data endpoint source.
116  */
117 int snd_usb_endpoint_implicit_feedback_sink(struct snd_usb_endpoint *ep)
118 {
119 	return  ep->sync_master &&
120 		ep->sync_master->type == SND_USB_ENDPOINT_TYPE_DATA &&
121 		ep->type == SND_USB_ENDPOINT_TYPE_DATA &&
122 		usb_pipeout(ep->pipe);
123 }
124 
125 /*
126  * For streaming based on information derived from sync endpoints,
127  * prepare_outbound_urb_sizes() will call next_packet_size() to
128  * determine the number of samples to be sent in the next packet.
129  *
130  * For implicit feedback, next_packet_size() is unused.
131  */
132 int snd_usb_endpoint_next_packet_size(struct snd_usb_endpoint *ep)
133 {
134 	unsigned long flags;
135 	int ret;
136 
137 	if (ep->fill_max)
138 		return ep->maxframesize;
139 
140 	spin_lock_irqsave(&ep->lock, flags);
141 	ep->phase = (ep->phase & 0xffff)
142 		+ (ep->freqm << ep->datainterval);
143 	ret = min(ep->phase >> 16, ep->maxframesize);
144 	spin_unlock_irqrestore(&ep->lock, flags);
145 
146 	return ret;
147 }
148 
149 static void retire_outbound_urb(struct snd_usb_endpoint *ep,
150 				struct snd_urb_ctx *urb_ctx)
151 {
152 	if (ep->retire_data_urb)
153 		ep->retire_data_urb(ep->data_subs, urb_ctx->urb);
154 }
155 
156 static void retire_inbound_urb(struct snd_usb_endpoint *ep,
157 			       struct snd_urb_ctx *urb_ctx)
158 {
159 	struct urb *urb = urb_ctx->urb;
160 
161 	if (unlikely(ep->skip_packets > 0)) {
162 		ep->skip_packets--;
163 		return;
164 	}
165 
166 	if (ep->sync_slave)
167 		snd_usb_handle_sync_urb(ep->sync_slave, ep, urb);
168 
169 	if (ep->retire_data_urb)
170 		ep->retire_data_urb(ep->data_subs, urb);
171 }
172 
173 static void prepare_silent_urb(struct snd_usb_endpoint *ep,
174 			       struct snd_urb_ctx *ctx)
175 {
176 	struct urb *urb = ctx->urb;
177 	unsigned int offs = 0;
178 	unsigned int extra = 0;
179 	__le32 packet_length;
180 	int i;
181 
182 	/* For tx_length_quirk, put packet length at start of packet */
183 	if (ep->chip->tx_length_quirk)
184 		extra = sizeof(packet_length);
185 
186 	for (i = 0; i < ctx->packets; ++i) {
187 		unsigned int offset;
188 		unsigned int length;
189 		int counts;
190 
191 		if (ctx->packet_size[i])
192 			counts = ctx->packet_size[i];
193 		else
194 			counts = snd_usb_endpoint_next_packet_size(ep);
195 
196 		length = counts * ep->stride; /* number of silent bytes */
197 		offset = offs * ep->stride + extra * i;
198 		urb->iso_frame_desc[i].offset = offset;
199 		urb->iso_frame_desc[i].length = length + extra;
200 		if (extra) {
201 			packet_length = cpu_to_le32(length);
202 			memcpy(urb->transfer_buffer + offset,
203 			       &packet_length, sizeof(packet_length));
204 		}
205 		memset(urb->transfer_buffer + offset + extra,
206 		       ep->silence_value, length);
207 		offs += counts;
208 	}
209 
210 	urb->number_of_packets = ctx->packets;
211 	urb->transfer_buffer_length = offs * ep->stride + ctx->packets * extra;
212 }
213 
214 /*
215  * Prepare a PLAYBACK urb for submission to the bus.
216  */
217 static void prepare_outbound_urb(struct snd_usb_endpoint *ep,
218 				 struct snd_urb_ctx *ctx)
219 {
220 	struct urb *urb = ctx->urb;
221 	unsigned char *cp = urb->transfer_buffer;
222 
223 	urb->dev = ep->chip->dev; /* we need to set this at each time */
224 
225 	switch (ep->type) {
226 	case SND_USB_ENDPOINT_TYPE_DATA:
227 		if (ep->prepare_data_urb) {
228 			ep->prepare_data_urb(ep->data_subs, urb);
229 		} else {
230 			/* no data provider, so send silence */
231 			prepare_silent_urb(ep, ctx);
232 		}
233 		break;
234 
235 	case SND_USB_ENDPOINT_TYPE_SYNC:
236 		if (snd_usb_get_speed(ep->chip->dev) >= USB_SPEED_HIGH) {
237 			/*
238 			 * fill the length and offset of each urb descriptor.
239 			 * the fixed 12.13 frequency is passed as 16.16 through the pipe.
240 			 */
241 			urb->iso_frame_desc[0].length = 4;
242 			urb->iso_frame_desc[0].offset = 0;
243 			cp[0] = ep->freqn;
244 			cp[1] = ep->freqn >> 8;
245 			cp[2] = ep->freqn >> 16;
246 			cp[3] = ep->freqn >> 24;
247 		} else {
248 			/*
249 			 * fill the length and offset of each urb descriptor.
250 			 * the fixed 10.14 frequency is passed through the pipe.
251 			 */
252 			urb->iso_frame_desc[0].length = 3;
253 			urb->iso_frame_desc[0].offset = 0;
254 			cp[0] = ep->freqn >> 2;
255 			cp[1] = ep->freqn >> 10;
256 			cp[2] = ep->freqn >> 18;
257 		}
258 
259 		break;
260 	}
261 }
262 
263 /*
264  * Prepare a CAPTURE or SYNC urb for submission to the bus.
265  */
266 static inline void prepare_inbound_urb(struct snd_usb_endpoint *ep,
267 				       struct snd_urb_ctx *urb_ctx)
268 {
269 	int i, offs;
270 	struct urb *urb = urb_ctx->urb;
271 
272 	urb->dev = ep->chip->dev; /* we need to set this at each time */
273 
274 	switch (ep->type) {
275 	case SND_USB_ENDPOINT_TYPE_DATA:
276 		offs = 0;
277 		for (i = 0; i < urb_ctx->packets; i++) {
278 			urb->iso_frame_desc[i].offset = offs;
279 			urb->iso_frame_desc[i].length = ep->curpacksize;
280 			offs += ep->curpacksize;
281 		}
282 
283 		urb->transfer_buffer_length = offs;
284 		urb->number_of_packets = urb_ctx->packets;
285 		break;
286 
287 	case SND_USB_ENDPOINT_TYPE_SYNC:
288 		urb->iso_frame_desc[0].length = min(4u, ep->syncmaxsize);
289 		urb->iso_frame_desc[0].offset = 0;
290 		break;
291 	}
292 }
293 
294 /*
295  * Send output urbs that have been prepared previously. URBs are dequeued
296  * from ep->ready_playback_urbs and in case there there aren't any available
297  * or there are no packets that have been prepared, this function does
298  * nothing.
299  *
300  * The reason why the functionality of sending and preparing URBs is separated
301  * is that host controllers don't guarantee the order in which they return
302  * inbound and outbound packets to their submitters.
303  *
304  * This function is only used for implicit feedback endpoints. For endpoints
305  * driven by dedicated sync endpoints, URBs are immediately re-submitted
306  * from their completion handler.
307  */
308 static void queue_pending_output_urbs(struct snd_usb_endpoint *ep)
309 {
310 	while (test_bit(EP_FLAG_RUNNING, &ep->flags)) {
311 
312 		unsigned long flags;
313 		struct snd_usb_packet_info *uninitialized_var(packet);
314 		struct snd_urb_ctx *ctx = NULL;
315 		int err, i;
316 
317 		spin_lock_irqsave(&ep->lock, flags);
318 		if (ep->next_packet_read_pos != ep->next_packet_write_pos) {
319 			packet = ep->next_packet + ep->next_packet_read_pos;
320 			ep->next_packet_read_pos++;
321 			ep->next_packet_read_pos %= MAX_URBS;
322 
323 			/* take URB out of FIFO */
324 			if (!list_empty(&ep->ready_playback_urbs))
325 				ctx = list_first_entry(&ep->ready_playback_urbs,
326 					       struct snd_urb_ctx, ready_list);
327 		}
328 		spin_unlock_irqrestore(&ep->lock, flags);
329 
330 		if (ctx == NULL)
331 			return;
332 
333 		list_del_init(&ctx->ready_list);
334 
335 		/* copy over the length information */
336 		for (i = 0; i < packet->packets; i++)
337 			ctx->packet_size[i] = packet->packet_size[i];
338 
339 		/* call the data handler to fill in playback data */
340 		prepare_outbound_urb(ep, ctx);
341 
342 		err = usb_submit_urb(ctx->urb, GFP_ATOMIC);
343 		if (err < 0)
344 			usb_audio_err(ep->chip,
345 				"Unable to submit urb #%d: %d (urb %p)\n",
346 				ctx->index, err, ctx->urb);
347 		else
348 			set_bit(ctx->index, &ep->active_mask);
349 	}
350 }
351 
352 /*
353  * complete callback for urbs
354  */
355 static void snd_complete_urb(struct urb *urb)
356 {
357 	struct snd_urb_ctx *ctx = urb->context;
358 	struct snd_usb_endpoint *ep = ctx->ep;
359 	struct snd_pcm_substream *substream;
360 	unsigned long flags;
361 	int err;
362 
363 	if (unlikely(urb->status == -ENOENT ||		/* unlinked */
364 		     urb->status == -ENODEV ||		/* device removed */
365 		     urb->status == -ECONNRESET ||	/* unlinked */
366 		     urb->status == -ESHUTDOWN))	/* device disabled */
367 		goto exit_clear;
368 	/* device disconnected */
369 	if (unlikely(atomic_read(&ep->chip->shutdown)))
370 		goto exit_clear;
371 
372 	if (unlikely(!test_bit(EP_FLAG_RUNNING, &ep->flags)))
373 		goto exit_clear;
374 
375 	if (usb_pipeout(ep->pipe)) {
376 		retire_outbound_urb(ep, ctx);
377 		/* can be stopped during retire callback */
378 		if (unlikely(!test_bit(EP_FLAG_RUNNING, &ep->flags)))
379 			goto exit_clear;
380 
381 		if (snd_usb_endpoint_implicit_feedback_sink(ep)) {
382 			spin_lock_irqsave(&ep->lock, flags);
383 			list_add_tail(&ctx->ready_list, &ep->ready_playback_urbs);
384 			spin_unlock_irqrestore(&ep->lock, flags);
385 			queue_pending_output_urbs(ep);
386 
387 			goto exit_clear;
388 		}
389 
390 		prepare_outbound_urb(ep, ctx);
391 	} else {
392 		retire_inbound_urb(ep, ctx);
393 		/* can be stopped during retire callback */
394 		if (unlikely(!test_bit(EP_FLAG_RUNNING, &ep->flags)))
395 			goto exit_clear;
396 
397 		prepare_inbound_urb(ep, ctx);
398 	}
399 
400 	err = usb_submit_urb(urb, GFP_ATOMIC);
401 	if (err == 0)
402 		return;
403 
404 	usb_audio_err(ep->chip, "cannot submit urb (err = %d)\n", err);
405 	if (ep->data_subs && ep->data_subs->pcm_substream) {
406 		substream = ep->data_subs->pcm_substream;
407 		snd_pcm_stop_xrun(substream);
408 	}
409 
410 exit_clear:
411 	clear_bit(ctx->index, &ep->active_mask);
412 }
413 
414 /**
415  * snd_usb_add_endpoint: Add an endpoint to an USB audio chip
416  *
417  * @chip: The chip
418  * @alts: The USB host interface
419  * @ep_num: The number of the endpoint to use
420  * @direction: SNDRV_PCM_STREAM_PLAYBACK or SNDRV_PCM_STREAM_CAPTURE
421  * @type: SND_USB_ENDPOINT_TYPE_DATA or SND_USB_ENDPOINT_TYPE_SYNC
422  *
423  * If the requested endpoint has not been added to the given chip before,
424  * a new instance is created. Otherwise, a pointer to the previoulsy
425  * created instance is returned. In case of any error, NULL is returned.
426  *
427  * New endpoints will be added to chip->ep_list and must be freed by
428  * calling snd_usb_endpoint_free().
429  *
430  * For SND_USB_ENDPOINT_TYPE_SYNC, the caller needs to guarantee that
431  * bNumEndpoints > 1 beforehand.
432  */
433 struct snd_usb_endpoint *snd_usb_add_endpoint(struct snd_usb_audio *chip,
434 					      struct usb_host_interface *alts,
435 					      int ep_num, int direction, int type)
436 {
437 	struct snd_usb_endpoint *ep;
438 	int is_playback = direction == SNDRV_PCM_STREAM_PLAYBACK;
439 
440 	if (WARN_ON(!alts))
441 		return NULL;
442 
443 	mutex_lock(&chip->mutex);
444 
445 	list_for_each_entry(ep, &chip->ep_list, list) {
446 		if (ep->ep_num == ep_num &&
447 		    ep->iface == alts->desc.bInterfaceNumber &&
448 		    ep->altsetting == alts->desc.bAlternateSetting) {
449 			usb_audio_dbg(ep->chip,
450 				      "Re-using EP %x in iface %d,%d @%p\n",
451 					ep_num, ep->iface, ep->altsetting, ep);
452 			goto __exit_unlock;
453 		}
454 	}
455 
456 	usb_audio_dbg(chip, "Creating new %s %s endpoint #%x\n",
457 		    is_playback ? "playback" : "capture",
458 		    type == SND_USB_ENDPOINT_TYPE_DATA ? "data" : "sync",
459 		    ep_num);
460 
461 	ep = kzalloc(sizeof(*ep), GFP_KERNEL);
462 	if (!ep)
463 		goto __exit_unlock;
464 
465 	ep->chip = chip;
466 	spin_lock_init(&ep->lock);
467 	ep->type = type;
468 	ep->ep_num = ep_num;
469 	ep->iface = alts->desc.bInterfaceNumber;
470 	ep->altsetting = alts->desc.bAlternateSetting;
471 	INIT_LIST_HEAD(&ep->ready_playback_urbs);
472 	ep_num &= USB_ENDPOINT_NUMBER_MASK;
473 
474 	if (is_playback)
475 		ep->pipe = usb_sndisocpipe(chip->dev, ep_num);
476 	else
477 		ep->pipe = usb_rcvisocpipe(chip->dev, ep_num);
478 
479 	if (type == SND_USB_ENDPOINT_TYPE_SYNC) {
480 		if (get_endpoint(alts, 1)->bLength >= USB_DT_ENDPOINT_AUDIO_SIZE &&
481 		    get_endpoint(alts, 1)->bRefresh >= 1 &&
482 		    get_endpoint(alts, 1)->bRefresh <= 9)
483 			ep->syncinterval = get_endpoint(alts, 1)->bRefresh;
484 		else if (snd_usb_get_speed(chip->dev) == USB_SPEED_FULL)
485 			ep->syncinterval = 1;
486 		else if (get_endpoint(alts, 1)->bInterval >= 1 &&
487 			 get_endpoint(alts, 1)->bInterval <= 16)
488 			ep->syncinterval = get_endpoint(alts, 1)->bInterval - 1;
489 		else
490 			ep->syncinterval = 3;
491 
492 		ep->syncmaxsize = le16_to_cpu(get_endpoint(alts, 1)->wMaxPacketSize);
493 	}
494 
495 	list_add_tail(&ep->list, &chip->ep_list);
496 
497 __exit_unlock:
498 	mutex_unlock(&chip->mutex);
499 
500 	return ep;
501 }
502 
503 /*
504  *  wait until all urbs are processed.
505  */
506 static int wait_clear_urbs(struct snd_usb_endpoint *ep)
507 {
508 	unsigned long end_time = jiffies + msecs_to_jiffies(1000);
509 	int alive;
510 
511 	do {
512 		alive = bitmap_weight(&ep->active_mask, ep->nurbs);
513 		if (!alive)
514 			break;
515 
516 		schedule_timeout_uninterruptible(1);
517 	} while (time_before(jiffies, end_time));
518 
519 	if (alive)
520 		usb_audio_err(ep->chip,
521 			"timeout: still %d active urbs on EP #%x\n",
522 			alive, ep->ep_num);
523 	clear_bit(EP_FLAG_STOPPING, &ep->flags);
524 
525 	ep->data_subs = NULL;
526 	ep->sync_slave = NULL;
527 	ep->retire_data_urb = NULL;
528 	ep->prepare_data_urb = NULL;
529 
530 	return 0;
531 }
532 
533 /* sync the pending stop operation;
534  * this function itself doesn't trigger the stop operation
535  */
536 void snd_usb_endpoint_sync_pending_stop(struct snd_usb_endpoint *ep)
537 {
538 	if (ep && test_bit(EP_FLAG_STOPPING, &ep->flags))
539 		wait_clear_urbs(ep);
540 }
541 
542 /*
543  * unlink active urbs.
544  */
545 static int deactivate_urbs(struct snd_usb_endpoint *ep, bool force)
546 {
547 	unsigned int i;
548 
549 	if (!force && atomic_read(&ep->chip->shutdown)) /* to be sure... */
550 		return -EBADFD;
551 
552 	clear_bit(EP_FLAG_RUNNING, &ep->flags);
553 
554 	INIT_LIST_HEAD(&ep->ready_playback_urbs);
555 	ep->next_packet_read_pos = 0;
556 	ep->next_packet_write_pos = 0;
557 
558 	for (i = 0; i < ep->nurbs; i++) {
559 		if (test_bit(i, &ep->active_mask)) {
560 			if (!test_and_set_bit(i, &ep->unlink_mask)) {
561 				struct urb *u = ep->urb[i].urb;
562 				usb_unlink_urb(u);
563 			}
564 		}
565 	}
566 
567 	return 0;
568 }
569 
570 /*
571  * release an endpoint's urbs
572  */
573 static void release_urbs(struct snd_usb_endpoint *ep, int force)
574 {
575 	int i;
576 
577 	/* route incoming urbs to nirvana */
578 	ep->retire_data_urb = NULL;
579 	ep->prepare_data_urb = NULL;
580 
581 	/* stop urbs */
582 	deactivate_urbs(ep, force);
583 	wait_clear_urbs(ep);
584 
585 	for (i = 0; i < ep->nurbs; i++)
586 		release_urb_ctx(&ep->urb[i]);
587 
588 	if (ep->syncbuf)
589 		usb_free_coherent(ep->chip->dev, SYNC_URBS * 4,
590 				  ep->syncbuf, ep->sync_dma);
591 
592 	ep->syncbuf = NULL;
593 	ep->nurbs = 0;
594 }
595 
596 /*
597  * configure a data endpoint
598  */
599 static int data_ep_set_params(struct snd_usb_endpoint *ep,
600 			      snd_pcm_format_t pcm_format,
601 			      unsigned int channels,
602 			      unsigned int period_bytes,
603 			      unsigned int frames_per_period,
604 			      unsigned int periods_per_buffer,
605 			      struct audioformat *fmt,
606 			      struct snd_usb_endpoint *sync_ep)
607 {
608 	unsigned int maxsize, minsize, packs_per_ms, max_packs_per_urb;
609 	unsigned int max_packs_per_period, urbs_per_period, urb_packs;
610 	unsigned int max_urbs, i;
611 	int frame_bits = snd_pcm_format_physical_width(pcm_format) * channels;
612 	int tx_length_quirk = (ep->chip->tx_length_quirk &&
613 			       usb_pipeout(ep->pipe));
614 
615 	if (pcm_format == SNDRV_PCM_FORMAT_DSD_U16_LE && fmt->dsd_dop) {
616 		/*
617 		 * When operating in DSD DOP mode, the size of a sample frame
618 		 * in hardware differs from the actual physical format width
619 		 * because we need to make room for the DOP markers.
620 		 */
621 		frame_bits += channels << 3;
622 	}
623 
624 	ep->datainterval = fmt->datainterval;
625 	ep->stride = frame_bits >> 3;
626 
627 	switch (pcm_format) {
628 	case SNDRV_PCM_FORMAT_U8:
629 		ep->silence_value = 0x80;
630 		break;
631 	case SNDRV_PCM_FORMAT_DSD_U8:
632 	case SNDRV_PCM_FORMAT_DSD_U16_LE:
633 	case SNDRV_PCM_FORMAT_DSD_U32_LE:
634 	case SNDRV_PCM_FORMAT_DSD_U16_BE:
635 	case SNDRV_PCM_FORMAT_DSD_U32_BE:
636 		ep->silence_value = 0x69;
637 		break;
638 	default:
639 		ep->silence_value = 0;
640 	}
641 
642 	/* assume max. frequency is 50% higher than nominal */
643 	ep->freqmax = ep->freqn + (ep->freqn >> 1);
644 	/* Round up freqmax to nearest integer in order to calculate maximum
645 	 * packet size, which must represent a whole number of frames.
646 	 * This is accomplished by adding 0x0.ffff before converting the
647 	 * Q16.16 format into integer.
648 	 * In order to accurately calculate the maximum packet size when
649 	 * the data interval is more than 1 (i.e. ep->datainterval > 0),
650 	 * multiply by the data interval prior to rounding. For instance,
651 	 * a freqmax of 41 kHz will result in a max packet size of 6 (5.125)
652 	 * frames with a data interval of 1, but 11 (10.25) frames with a
653 	 * data interval of 2.
654 	 * (ep->freqmax << ep->datainterval overflows at 8.192 MHz for the
655 	 * maximum datainterval value of 3, at USB full speed, higher for
656 	 * USB high speed, noting that ep->freqmax is in units of
657 	 * frames per packet in Q16.16 format.)
658 	 */
659 	maxsize = (((ep->freqmax << ep->datainterval) + 0xffff) >> 16) *
660 			 (frame_bits >> 3);
661 	if (tx_length_quirk)
662 		maxsize += sizeof(__le32); /* Space for length descriptor */
663 	/* but wMaxPacketSize might reduce this */
664 	if (ep->maxpacksize && ep->maxpacksize < maxsize) {
665 		/* whatever fits into a max. size packet */
666 		unsigned int data_maxsize = maxsize = ep->maxpacksize;
667 
668 		if (tx_length_quirk)
669 			/* Need to remove the length descriptor to calc freq */
670 			data_maxsize -= sizeof(__le32);
671 		ep->freqmax = (data_maxsize / (frame_bits >> 3))
672 				<< (16 - ep->datainterval);
673 	}
674 
675 	if (ep->fill_max)
676 		ep->curpacksize = ep->maxpacksize;
677 	else
678 		ep->curpacksize = maxsize;
679 
680 	if (snd_usb_get_speed(ep->chip->dev) != USB_SPEED_FULL) {
681 		packs_per_ms = 8 >> ep->datainterval;
682 		max_packs_per_urb = MAX_PACKS_HS;
683 	} else {
684 		packs_per_ms = 1;
685 		max_packs_per_urb = MAX_PACKS;
686 	}
687 	if (sync_ep && !snd_usb_endpoint_implicit_feedback_sink(ep))
688 		max_packs_per_urb = min(max_packs_per_urb,
689 					1U << sync_ep->syncinterval);
690 	max_packs_per_urb = max(1u, max_packs_per_urb >> ep->datainterval);
691 
692 	/*
693 	 * Capture endpoints need to use small URBs because there's no way
694 	 * to tell in advance where the next period will end, and we don't
695 	 * want the next URB to complete much after the period ends.
696 	 *
697 	 * Playback endpoints with implicit sync much use the same parameters
698 	 * as their corresponding capture endpoint.
699 	 */
700 	if (usb_pipein(ep->pipe) ||
701 			snd_usb_endpoint_implicit_feedback_sink(ep)) {
702 
703 		urb_packs = packs_per_ms;
704 		/*
705 		 * Wireless devices can poll at a max rate of once per 4ms.
706 		 * For dataintervals less than 5, increase the packet count to
707 		 * allow the host controller to use bursting to fill in the
708 		 * gaps.
709 		 */
710 		if (snd_usb_get_speed(ep->chip->dev) == USB_SPEED_WIRELESS) {
711 			int interval = ep->datainterval;
712 			while (interval < 5) {
713 				urb_packs <<= 1;
714 				++interval;
715 			}
716 		}
717 		/* make capture URBs <= 1 ms and smaller than a period */
718 		urb_packs = min(max_packs_per_urb, urb_packs);
719 		while (urb_packs > 1 && urb_packs * maxsize >= period_bytes)
720 			urb_packs >>= 1;
721 		ep->nurbs = MAX_URBS;
722 
723 	/*
724 	 * Playback endpoints without implicit sync are adjusted so that
725 	 * a period fits as evenly as possible in the smallest number of
726 	 * URBs.  The total number of URBs is adjusted to the size of the
727 	 * ALSA buffer, subject to the MAX_URBS and MAX_QUEUE limits.
728 	 */
729 	} else {
730 		/* determine how small a packet can be */
731 		minsize = (ep->freqn >> (16 - ep->datainterval)) *
732 				(frame_bits >> 3);
733 		/* with sync from device, assume it can be 12% lower */
734 		if (sync_ep)
735 			minsize -= minsize >> 3;
736 		minsize = max(minsize, 1u);
737 
738 		/* how many packets will contain an entire ALSA period? */
739 		max_packs_per_period = DIV_ROUND_UP(period_bytes, minsize);
740 
741 		/* how many URBs will contain a period? */
742 		urbs_per_period = DIV_ROUND_UP(max_packs_per_period,
743 				max_packs_per_urb);
744 		/* how many packets are needed in each URB? */
745 		urb_packs = DIV_ROUND_UP(max_packs_per_period, urbs_per_period);
746 
747 		/* limit the number of frames in a single URB */
748 		ep->max_urb_frames = DIV_ROUND_UP(frames_per_period,
749 					urbs_per_period);
750 
751 		/* try to use enough URBs to contain an entire ALSA buffer */
752 		max_urbs = min((unsigned) MAX_URBS,
753 				MAX_QUEUE * packs_per_ms / urb_packs);
754 		ep->nurbs = min(max_urbs, urbs_per_period * periods_per_buffer);
755 	}
756 
757 	/* allocate and initialize data urbs */
758 	for (i = 0; i < ep->nurbs; i++) {
759 		struct snd_urb_ctx *u = &ep->urb[i];
760 		u->index = i;
761 		u->ep = ep;
762 		u->packets = urb_packs;
763 		u->buffer_size = maxsize * u->packets;
764 
765 		if (fmt->fmt_type == UAC_FORMAT_TYPE_II)
766 			u->packets++; /* for transfer delimiter */
767 		u->urb = usb_alloc_urb(u->packets, GFP_KERNEL);
768 		if (!u->urb)
769 			goto out_of_memory;
770 
771 		u->urb->transfer_buffer =
772 			usb_alloc_coherent(ep->chip->dev, u->buffer_size,
773 					   GFP_KERNEL, &u->urb->transfer_dma);
774 		if (!u->urb->transfer_buffer)
775 			goto out_of_memory;
776 		u->urb->pipe = ep->pipe;
777 		u->urb->transfer_flags = URB_NO_TRANSFER_DMA_MAP;
778 		u->urb->interval = 1 << ep->datainterval;
779 		u->urb->context = u;
780 		u->urb->complete = snd_complete_urb;
781 		INIT_LIST_HEAD(&u->ready_list);
782 	}
783 
784 	return 0;
785 
786 out_of_memory:
787 	release_urbs(ep, 0);
788 	return -ENOMEM;
789 }
790 
791 /*
792  * configure a sync endpoint
793  */
794 static int sync_ep_set_params(struct snd_usb_endpoint *ep)
795 {
796 	int i;
797 
798 	ep->syncbuf = usb_alloc_coherent(ep->chip->dev, SYNC_URBS * 4,
799 					 GFP_KERNEL, &ep->sync_dma);
800 	if (!ep->syncbuf)
801 		return -ENOMEM;
802 
803 	for (i = 0; i < SYNC_URBS; i++) {
804 		struct snd_urb_ctx *u = &ep->urb[i];
805 		u->index = i;
806 		u->ep = ep;
807 		u->packets = 1;
808 		u->urb = usb_alloc_urb(1, GFP_KERNEL);
809 		if (!u->urb)
810 			goto out_of_memory;
811 		u->urb->transfer_buffer = ep->syncbuf + i * 4;
812 		u->urb->transfer_dma = ep->sync_dma + i * 4;
813 		u->urb->transfer_buffer_length = 4;
814 		u->urb->pipe = ep->pipe;
815 		u->urb->transfer_flags = URB_NO_TRANSFER_DMA_MAP;
816 		u->urb->number_of_packets = 1;
817 		u->urb->interval = 1 << ep->syncinterval;
818 		u->urb->context = u;
819 		u->urb->complete = snd_complete_urb;
820 	}
821 
822 	ep->nurbs = SYNC_URBS;
823 
824 	return 0;
825 
826 out_of_memory:
827 	release_urbs(ep, 0);
828 	return -ENOMEM;
829 }
830 
831 /**
832  * snd_usb_endpoint_set_params: configure an snd_usb_endpoint
833  *
834  * @ep: the snd_usb_endpoint to configure
835  * @pcm_format: the audio fomat.
836  * @channels: the number of audio channels.
837  * @period_bytes: the number of bytes in one alsa period.
838  * @period_frames: the number of frames in one alsa period.
839  * @buffer_periods: the number of periods in one alsa buffer.
840  * @rate: the frame rate.
841  * @fmt: the USB audio format information
842  * @sync_ep: the sync endpoint to use, if any
843  *
844  * Determine the number of URBs to be used on this endpoint.
845  * An endpoint must be configured before it can be started.
846  * An endpoint that is already running can not be reconfigured.
847  */
848 int snd_usb_endpoint_set_params(struct snd_usb_endpoint *ep,
849 				snd_pcm_format_t pcm_format,
850 				unsigned int channels,
851 				unsigned int period_bytes,
852 				unsigned int period_frames,
853 				unsigned int buffer_periods,
854 				unsigned int rate,
855 				struct audioformat *fmt,
856 				struct snd_usb_endpoint *sync_ep)
857 {
858 	int err;
859 
860 	if (ep->use_count != 0) {
861 		usb_audio_warn(ep->chip,
862 			 "Unable to change format on ep #%x: already in use\n",
863 			 ep->ep_num);
864 		return -EBUSY;
865 	}
866 
867 	/* release old buffers, if any */
868 	release_urbs(ep, 0);
869 
870 	ep->datainterval = fmt->datainterval;
871 	ep->maxpacksize = fmt->maxpacksize;
872 	ep->fill_max = !!(fmt->attributes & UAC_EP_CS_ATTR_FILL_MAX);
873 
874 	if (snd_usb_get_speed(ep->chip->dev) == USB_SPEED_FULL)
875 		ep->freqn = get_usb_full_speed_rate(rate);
876 	else
877 		ep->freqn = get_usb_high_speed_rate(rate);
878 
879 	/* calculate the frequency in 16.16 format */
880 	ep->freqm = ep->freqn;
881 	ep->freqshift = INT_MIN;
882 
883 	ep->phase = 0;
884 
885 	switch (ep->type) {
886 	case  SND_USB_ENDPOINT_TYPE_DATA:
887 		err = data_ep_set_params(ep, pcm_format, channels,
888 					 period_bytes, period_frames,
889 					 buffer_periods, fmt, sync_ep);
890 		break;
891 	case  SND_USB_ENDPOINT_TYPE_SYNC:
892 		err = sync_ep_set_params(ep);
893 		break;
894 	default:
895 		err = -EINVAL;
896 	}
897 
898 	usb_audio_dbg(ep->chip,
899 		"Setting params for ep #%x (type %d, %d urbs), ret=%d\n",
900 		ep->ep_num, ep->type, ep->nurbs, err);
901 
902 	return err;
903 }
904 
905 /**
906  * snd_usb_endpoint_start: start an snd_usb_endpoint
907  *
908  * @ep: the endpoint to start
909  *
910  * A call to this function will increment the use count of the endpoint.
911  * In case it is not already running, the URBs for this endpoint will be
912  * submitted. Otherwise, this function does nothing.
913  *
914  * Must be balanced to calls of snd_usb_endpoint_stop().
915  *
916  * Returns an error if the URB submission failed, 0 in all other cases.
917  */
918 int snd_usb_endpoint_start(struct snd_usb_endpoint *ep)
919 {
920 	int err;
921 	unsigned int i;
922 
923 	if (atomic_read(&ep->chip->shutdown))
924 		return -EBADFD;
925 
926 	/* already running? */
927 	if (++ep->use_count != 1)
928 		return 0;
929 
930 	/* just to be sure */
931 	deactivate_urbs(ep, false);
932 
933 	ep->active_mask = 0;
934 	ep->unlink_mask = 0;
935 	ep->phase = 0;
936 
937 	snd_usb_endpoint_start_quirk(ep);
938 
939 	/*
940 	 * If this endpoint has a data endpoint as implicit feedback source,
941 	 * don't start the urbs here. Instead, mark them all as available,
942 	 * wait for the record urbs to return and queue the playback urbs
943 	 * from that context.
944 	 */
945 
946 	set_bit(EP_FLAG_RUNNING, &ep->flags);
947 
948 	if (snd_usb_endpoint_implicit_feedback_sink(ep)) {
949 		for (i = 0; i < ep->nurbs; i++) {
950 			struct snd_urb_ctx *ctx = ep->urb + i;
951 			list_add_tail(&ctx->ready_list, &ep->ready_playback_urbs);
952 		}
953 
954 		return 0;
955 	}
956 
957 	for (i = 0; i < ep->nurbs; i++) {
958 		struct urb *urb = ep->urb[i].urb;
959 
960 		if (snd_BUG_ON(!urb))
961 			goto __error;
962 
963 		if (usb_pipeout(ep->pipe)) {
964 			prepare_outbound_urb(ep, urb->context);
965 		} else {
966 			prepare_inbound_urb(ep, urb->context);
967 		}
968 
969 		err = usb_submit_urb(urb, GFP_ATOMIC);
970 		if (err < 0) {
971 			usb_audio_err(ep->chip,
972 				"cannot submit urb %d, error %d: %s\n",
973 				i, err, usb_error_string(err));
974 			goto __error;
975 		}
976 		set_bit(i, &ep->active_mask);
977 	}
978 
979 	return 0;
980 
981 __error:
982 	clear_bit(EP_FLAG_RUNNING, &ep->flags);
983 	ep->use_count--;
984 	deactivate_urbs(ep, false);
985 	return -EPIPE;
986 }
987 
988 /**
989  * snd_usb_endpoint_stop: stop an snd_usb_endpoint
990  *
991  * @ep: the endpoint to stop (may be NULL)
992  *
993  * A call to this function will decrement the use count of the endpoint.
994  * In case the last user has requested the endpoint stop, the URBs will
995  * actually be deactivated.
996  *
997  * Must be balanced to calls of snd_usb_endpoint_start().
998  *
999  * The caller needs to synchronize the pending stop operation via
1000  * snd_usb_endpoint_sync_pending_stop().
1001  */
1002 void snd_usb_endpoint_stop(struct snd_usb_endpoint *ep)
1003 {
1004 	if (!ep)
1005 		return;
1006 
1007 	if (snd_BUG_ON(ep->use_count == 0))
1008 		return;
1009 
1010 	if (--ep->use_count == 0) {
1011 		deactivate_urbs(ep, false);
1012 		set_bit(EP_FLAG_STOPPING, &ep->flags);
1013 	}
1014 }
1015 
1016 /**
1017  * snd_usb_endpoint_deactivate: deactivate an snd_usb_endpoint
1018  *
1019  * @ep: the endpoint to deactivate
1020  *
1021  * If the endpoint is not currently in use, this functions will
1022  * deactivate its associated URBs.
1023  *
1024  * In case of any active users, this functions does nothing.
1025  */
1026 void snd_usb_endpoint_deactivate(struct snd_usb_endpoint *ep)
1027 {
1028 	if (!ep)
1029 		return;
1030 
1031 	if (ep->use_count != 0)
1032 		return;
1033 
1034 	deactivate_urbs(ep, true);
1035 	wait_clear_urbs(ep);
1036 }
1037 
1038 /**
1039  * snd_usb_endpoint_release: Tear down an snd_usb_endpoint
1040  *
1041  * @ep: the endpoint to release
1042  *
1043  * This function does not care for the endpoint's use count but will tear
1044  * down all the streaming URBs immediately.
1045  */
1046 void snd_usb_endpoint_release(struct snd_usb_endpoint *ep)
1047 {
1048 	release_urbs(ep, 1);
1049 }
1050 
1051 /**
1052  * snd_usb_endpoint_free: Free the resources of an snd_usb_endpoint
1053  *
1054  * @ep: the endpoint to free
1055  *
1056  * This free all resources of the given ep.
1057  */
1058 void snd_usb_endpoint_free(struct snd_usb_endpoint *ep)
1059 {
1060 	kfree(ep);
1061 }
1062 
1063 /**
1064  * snd_usb_handle_sync_urb: parse an USB sync packet
1065  *
1066  * @ep: the endpoint to handle the packet
1067  * @sender: the sending endpoint
1068  * @urb: the received packet
1069  *
1070  * This function is called from the context of an endpoint that received
1071  * the packet and is used to let another endpoint object handle the payload.
1072  */
1073 void snd_usb_handle_sync_urb(struct snd_usb_endpoint *ep,
1074 			     struct snd_usb_endpoint *sender,
1075 			     const struct urb *urb)
1076 {
1077 	int shift;
1078 	unsigned int f;
1079 	unsigned long flags;
1080 
1081 	snd_BUG_ON(ep == sender);
1082 
1083 	/*
1084 	 * In case the endpoint is operating in implicit feedback mode, prepare
1085 	 * a new outbound URB that has the same layout as the received packet
1086 	 * and add it to the list of pending urbs. queue_pending_output_urbs()
1087 	 * will take care of them later.
1088 	 */
1089 	if (snd_usb_endpoint_implicit_feedback_sink(ep) &&
1090 	    ep->use_count != 0) {
1091 
1092 		/* implicit feedback case */
1093 		int i, bytes = 0;
1094 		struct snd_urb_ctx *in_ctx;
1095 		struct snd_usb_packet_info *out_packet;
1096 
1097 		in_ctx = urb->context;
1098 
1099 		/* Count overall packet size */
1100 		for (i = 0; i < in_ctx->packets; i++)
1101 			if (urb->iso_frame_desc[i].status == 0)
1102 				bytes += urb->iso_frame_desc[i].actual_length;
1103 
1104 		/*
1105 		 * skip empty packets. At least M-Audio's Fast Track Ultra stops
1106 		 * streaming once it received a 0-byte OUT URB
1107 		 */
1108 		if (bytes == 0)
1109 			return;
1110 
1111 		spin_lock_irqsave(&ep->lock, flags);
1112 		out_packet = ep->next_packet + ep->next_packet_write_pos;
1113 
1114 		/*
1115 		 * Iterate through the inbound packet and prepare the lengths
1116 		 * for the output packet. The OUT packet we are about to send
1117 		 * will have the same amount of payload bytes per stride as the
1118 		 * IN packet we just received. Since the actual size is scaled
1119 		 * by the stride, use the sender stride to calculate the length
1120 		 * in case the number of channels differ between the implicitly
1121 		 * fed-back endpoint and the synchronizing endpoint.
1122 		 */
1123 
1124 		out_packet->packets = in_ctx->packets;
1125 		for (i = 0; i < in_ctx->packets; i++) {
1126 			if (urb->iso_frame_desc[i].status == 0)
1127 				out_packet->packet_size[i] =
1128 					urb->iso_frame_desc[i].actual_length / sender->stride;
1129 			else
1130 				out_packet->packet_size[i] = 0;
1131 		}
1132 
1133 		ep->next_packet_write_pos++;
1134 		ep->next_packet_write_pos %= MAX_URBS;
1135 		spin_unlock_irqrestore(&ep->lock, flags);
1136 		queue_pending_output_urbs(ep);
1137 
1138 		return;
1139 	}
1140 
1141 	/*
1142 	 * process after playback sync complete
1143 	 *
1144 	 * Full speed devices report feedback values in 10.14 format as samples
1145 	 * per frame, high speed devices in 16.16 format as samples per
1146 	 * microframe.
1147 	 *
1148 	 * Because the Audio Class 1 spec was written before USB 2.0, many high
1149 	 * speed devices use a wrong interpretation, some others use an
1150 	 * entirely different format.
1151 	 *
1152 	 * Therefore, we cannot predict what format any particular device uses
1153 	 * and must detect it automatically.
1154 	 */
1155 
1156 	if (urb->iso_frame_desc[0].status != 0 ||
1157 	    urb->iso_frame_desc[0].actual_length < 3)
1158 		return;
1159 
1160 	f = le32_to_cpup(urb->transfer_buffer);
1161 	if (urb->iso_frame_desc[0].actual_length == 3)
1162 		f &= 0x00ffffff;
1163 	else
1164 		f &= 0x0fffffff;
1165 
1166 	if (f == 0)
1167 		return;
1168 
1169 	if (unlikely(sender->tenor_fb_quirk)) {
1170 		/*
1171 		 * Devices based on Tenor 8802 chipsets (TEAC UD-H01
1172 		 * and others) sometimes change the feedback value
1173 		 * by +/- 0x1.0000.
1174 		 */
1175 		if (f < ep->freqn - 0x8000)
1176 			f += 0xf000;
1177 		else if (f > ep->freqn + 0x8000)
1178 			f -= 0xf000;
1179 	} else if (unlikely(ep->freqshift == INT_MIN)) {
1180 		/*
1181 		 * The first time we see a feedback value, determine its format
1182 		 * by shifting it left or right until it matches the nominal
1183 		 * frequency value.  This assumes that the feedback does not
1184 		 * differ from the nominal value more than +50% or -25%.
1185 		 */
1186 		shift = 0;
1187 		while (f < ep->freqn - ep->freqn / 4) {
1188 			f <<= 1;
1189 			shift++;
1190 		}
1191 		while (f > ep->freqn + ep->freqn / 2) {
1192 			f >>= 1;
1193 			shift--;
1194 		}
1195 		ep->freqshift = shift;
1196 	} else if (ep->freqshift >= 0)
1197 		f <<= ep->freqshift;
1198 	else
1199 		f >>= -ep->freqshift;
1200 
1201 	if (likely(f >= ep->freqn - ep->freqn / 8 && f <= ep->freqmax)) {
1202 		/*
1203 		 * If the frequency looks valid, set it.
1204 		 * This value is referred to in prepare_playback_urb().
1205 		 */
1206 		spin_lock_irqsave(&ep->lock, flags);
1207 		ep->freqm = f;
1208 		spin_unlock_irqrestore(&ep->lock, flags);
1209 	} else {
1210 		/*
1211 		 * Out of range; maybe the shift value is wrong.
1212 		 * Reset it so that we autodetect again the next time.
1213 		 */
1214 		ep->freqshift = INT_MIN;
1215 	}
1216 }
1217 
1218