xref: /linux/sound/usb/endpoint.c (revision 79d2e1919a2728ef49d938eb20ebd5903c14dfb0)
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 "clock.h"
22 #include "quirks.h"
23 
24 enum {
25 	EP_STATE_STOPPED,
26 	EP_STATE_RUNNING,
27 	EP_STATE_STOPPING,
28 };
29 
30 /* interface refcounting */
31 struct snd_usb_iface_ref {
32 	unsigned char iface;
33 	bool need_setup;
34 	int opened;
35 	int altset;
36 	struct list_head list;
37 };
38 
39 /* clock refcounting */
40 struct snd_usb_clock_ref {
41 	unsigned char clock;
42 	atomic_t locked;
43 	int opened;
44 	int rate;
45 	bool need_setup;
46 	struct list_head list;
47 };
48 
49 /*
50  * snd_usb_endpoint is a model that abstracts everything related to an
51  * USB endpoint and its streaming.
52  *
53  * There are functions to activate and deactivate the streaming URBs and
54  * optional callbacks to let the pcm logic handle the actual content of the
55  * packets for playback and record. Thus, the bus streaming and the audio
56  * handlers are fully decoupled.
57  *
58  * There are two different types of endpoints in audio applications.
59  *
60  * SND_USB_ENDPOINT_TYPE_DATA handles full audio data payload for both
61  * inbound and outbound traffic.
62  *
63  * SND_USB_ENDPOINT_TYPE_SYNC endpoints are for inbound traffic only and
64  * expect the payload to carry Q10.14 / Q16.16 formatted sync information
65  * (3 or 4 bytes).
66  *
67  * Each endpoint has to be configured prior to being used by calling
68  * snd_usb_endpoint_set_params().
69  *
70  * The model incorporates a reference counting, so that multiple users
71  * can call snd_usb_endpoint_start() and snd_usb_endpoint_stop(), and
72  * only the first user will effectively start the URBs, and only the last
73  * one to stop it will tear the URBs down again.
74  */
75 
76 /*
77  * convert a sampling rate into our full speed format (fs/1000 in Q16.16)
78  * this will overflow at approx 524 kHz
79  */
80 static inline unsigned get_usb_full_speed_rate(unsigned int rate)
81 {
82 	return ((rate << 13) + 62) / 125;
83 }
84 
85 /*
86  * convert a sampling rate into USB high speed format (fs/8000 in Q16.16)
87  * this will overflow at approx 4 MHz
88  */
89 static inline unsigned get_usb_high_speed_rate(unsigned int rate)
90 {
91 	return ((rate << 10) + 62) / 125;
92 }
93 
94 /*
95  * release a urb data
96  */
97 static void release_urb_ctx(struct snd_urb_ctx *u)
98 {
99 	if (u->urb && u->buffer_size)
100 		usb_free_coherent(u->ep->chip->dev, u->buffer_size,
101 				  u->urb->transfer_buffer,
102 				  u->urb->transfer_dma);
103 	usb_free_urb(u->urb);
104 	u->urb = NULL;
105 	u->buffer_size = 0;
106 }
107 
108 static const char *usb_error_string(int err)
109 {
110 	switch (err) {
111 	case -ENODEV:
112 		return "no device";
113 	case -ENOENT:
114 		return "endpoint not enabled";
115 	case -EPIPE:
116 		return "endpoint stalled";
117 	case -ENOSPC:
118 		return "not enough bandwidth";
119 	case -ESHUTDOWN:
120 		return "device disabled";
121 	case -EHOSTUNREACH:
122 		return "device suspended";
123 	case -EINVAL:
124 	case -EAGAIN:
125 	case -EFBIG:
126 	case -EMSGSIZE:
127 		return "internal error";
128 	default:
129 		return "unknown error";
130 	}
131 }
132 
133 static inline bool ep_state_running(struct snd_usb_endpoint *ep)
134 {
135 	return atomic_read(&ep->state) == EP_STATE_RUNNING;
136 }
137 
138 static inline bool ep_state_update(struct snd_usb_endpoint *ep, int old, int new)
139 {
140 	return atomic_try_cmpxchg(&ep->state, &old, new);
141 }
142 
143 /**
144  * snd_usb_endpoint_implicit_feedback_sink: Report endpoint usage type
145  *
146  * @ep: The snd_usb_endpoint
147  *
148  * Determine whether an endpoint is driven by an implicit feedback
149  * data endpoint source.
150  */
151 int snd_usb_endpoint_implicit_feedback_sink(struct snd_usb_endpoint *ep)
152 {
153 	return  ep->implicit_fb_sync && usb_pipeout(ep->pipe);
154 }
155 
156 /*
157  * Return the number of samples to be sent in the next packet
158  * for streaming based on information derived from sync endpoints
159  *
160  * This won't be used for implicit feedback which takes the packet size
161  * returned from the sync source
162  */
163 static int slave_next_packet_size(struct snd_usb_endpoint *ep,
164 				  unsigned int avail)
165 {
166 	unsigned long flags;
167 	unsigned int phase;
168 	int ret;
169 
170 	if (ep->fill_max)
171 		return ep->maxframesize;
172 
173 	spin_lock_irqsave(&ep->lock, flags);
174 	phase = (ep->phase & 0xffff) + (ep->freqm << ep->datainterval);
175 	ret = min(phase >> 16, ep->maxframesize);
176 	if (avail && ret >= avail)
177 		ret = -EAGAIN;
178 	else
179 		ep->phase = phase;
180 	spin_unlock_irqrestore(&ep->lock, flags);
181 
182 	return ret;
183 }
184 
185 /*
186  * Return the number of samples to be sent in the next packet
187  * for adaptive and synchronous endpoints
188  */
189 static int next_packet_size(struct snd_usb_endpoint *ep, unsigned int avail)
190 {
191 	unsigned int sample_accum;
192 	int ret;
193 
194 	if (ep->fill_max)
195 		return ep->maxframesize;
196 
197 	sample_accum = ep->sample_accum + ep->sample_rem;
198 	if (sample_accum >= ep->pps) {
199 		sample_accum -= ep->pps;
200 		ret = ep->packsize[1];
201 	} else {
202 		ret = ep->packsize[0];
203 	}
204 	if (avail && ret >= avail)
205 		ret = -EAGAIN;
206 	else
207 		ep->sample_accum = sample_accum;
208 
209 	return ret;
210 }
211 
212 /*
213  * snd_usb_endpoint_next_packet_size: Return the number of samples to be sent
214  * in the next packet
215  *
216  * If the size is equal or exceeds @avail, don't proceed but return -EAGAIN
217  * Exception: @avail = 0 for skipping the check.
218  */
219 int snd_usb_endpoint_next_packet_size(struct snd_usb_endpoint *ep,
220 				      struct snd_urb_ctx *ctx, int idx,
221 				      unsigned int avail)
222 {
223 	unsigned int packet;
224 
225 	packet = ctx->packet_size[idx];
226 	if (packet) {
227 		if (avail && packet >= avail)
228 			return -EAGAIN;
229 		return packet;
230 	}
231 
232 	if (ep->sync_source)
233 		return slave_next_packet_size(ep, avail);
234 	else
235 		return next_packet_size(ep, avail);
236 }
237 
238 static void call_retire_callback(struct snd_usb_endpoint *ep,
239 				 struct urb *urb)
240 {
241 	struct snd_usb_substream *data_subs;
242 
243 	data_subs = READ_ONCE(ep->data_subs);
244 	if (data_subs && ep->retire_data_urb)
245 		ep->retire_data_urb(data_subs, urb);
246 }
247 
248 static void retire_outbound_urb(struct snd_usb_endpoint *ep,
249 				struct snd_urb_ctx *urb_ctx)
250 {
251 	call_retire_callback(ep, urb_ctx->urb);
252 }
253 
254 static void snd_usb_handle_sync_urb(struct snd_usb_endpoint *ep,
255 				    struct snd_usb_endpoint *sender,
256 				    const struct urb *urb);
257 
258 static void retire_inbound_urb(struct snd_usb_endpoint *ep,
259 			       struct snd_urb_ctx *urb_ctx)
260 {
261 	struct urb *urb = urb_ctx->urb;
262 	struct snd_usb_endpoint *sync_sink;
263 
264 	if (unlikely(ep->skip_packets > 0)) {
265 		ep->skip_packets--;
266 		return;
267 	}
268 
269 	sync_sink = READ_ONCE(ep->sync_sink);
270 	if (sync_sink)
271 		snd_usb_handle_sync_urb(sync_sink, ep, urb);
272 
273 	call_retire_callback(ep, urb);
274 }
275 
276 static inline bool has_tx_length_quirk(struct snd_usb_audio *chip)
277 {
278 	return chip->quirk_flags & QUIRK_FLAG_TX_LENGTH;
279 }
280 
281 static void prepare_silent_urb(struct snd_usb_endpoint *ep,
282 			       struct snd_urb_ctx *ctx)
283 {
284 	struct urb *urb = ctx->urb;
285 	unsigned int offs = 0;
286 	unsigned int extra = 0;
287 	__le32 packet_length;
288 	int i;
289 
290 	/* For tx_length_quirk, put packet length at start of packet */
291 	if (has_tx_length_quirk(ep->chip))
292 		extra = sizeof(packet_length);
293 
294 	for (i = 0; i < ctx->packets; ++i) {
295 		unsigned int offset;
296 		unsigned int length;
297 		int counts;
298 
299 		counts = snd_usb_endpoint_next_packet_size(ep, ctx, i, 0);
300 		length = counts * ep->stride; /* number of silent bytes */
301 		offset = offs * ep->stride + extra * i;
302 		urb->iso_frame_desc[i].offset = offset;
303 		urb->iso_frame_desc[i].length = length + extra;
304 		if (extra) {
305 			packet_length = cpu_to_le32(length);
306 			memcpy(urb->transfer_buffer + offset,
307 			       &packet_length, sizeof(packet_length));
308 		}
309 		memset(urb->transfer_buffer + offset + extra,
310 		       ep->silence_value, length);
311 		offs += counts;
312 	}
313 
314 	urb->number_of_packets = ctx->packets;
315 	urb->transfer_buffer_length = offs * ep->stride + ctx->packets * extra;
316 	ctx->queued = 0;
317 }
318 
319 /*
320  * Prepare a PLAYBACK urb for submission to the bus.
321  */
322 static int prepare_outbound_urb(struct snd_usb_endpoint *ep,
323 				struct snd_urb_ctx *ctx,
324 				bool in_stream_lock)
325 {
326 	struct urb *urb = ctx->urb;
327 	unsigned char *cp = urb->transfer_buffer;
328 	struct snd_usb_substream *data_subs;
329 
330 	urb->dev = ep->chip->dev; /* we need to set this at each time */
331 
332 	switch (ep->type) {
333 	case SND_USB_ENDPOINT_TYPE_DATA:
334 		data_subs = READ_ONCE(ep->data_subs);
335 		if (data_subs && ep->prepare_data_urb)
336 			return ep->prepare_data_urb(data_subs, urb, in_stream_lock);
337 		/* no data provider, so send silence */
338 		prepare_silent_urb(ep, ctx);
339 		break;
340 
341 	case SND_USB_ENDPOINT_TYPE_SYNC:
342 		if (snd_usb_get_speed(ep->chip->dev) >= USB_SPEED_HIGH) {
343 			/*
344 			 * fill the length and offset of each urb descriptor.
345 			 * the fixed 12.13 frequency is passed as 16.16 through the pipe.
346 			 */
347 			urb->iso_frame_desc[0].length = 4;
348 			urb->iso_frame_desc[0].offset = 0;
349 			cp[0] = ep->freqn;
350 			cp[1] = ep->freqn >> 8;
351 			cp[2] = ep->freqn >> 16;
352 			cp[3] = ep->freqn >> 24;
353 		} else {
354 			/*
355 			 * fill the length and offset of each urb descriptor.
356 			 * the fixed 10.14 frequency is passed through the pipe.
357 			 */
358 			urb->iso_frame_desc[0].length = 3;
359 			urb->iso_frame_desc[0].offset = 0;
360 			cp[0] = ep->freqn >> 2;
361 			cp[1] = ep->freqn >> 10;
362 			cp[2] = ep->freqn >> 18;
363 		}
364 
365 		break;
366 	}
367 	return 0;
368 }
369 
370 /*
371  * Prepare a CAPTURE or SYNC urb for submission to the bus.
372  */
373 static int prepare_inbound_urb(struct snd_usb_endpoint *ep,
374 			       struct snd_urb_ctx *urb_ctx)
375 {
376 	int i, offs;
377 	struct urb *urb = urb_ctx->urb;
378 
379 	urb->dev = ep->chip->dev; /* we need to set this at each time */
380 
381 	switch (ep->type) {
382 	case SND_USB_ENDPOINT_TYPE_DATA:
383 		offs = 0;
384 		for (i = 0; i < urb_ctx->packets; i++) {
385 			urb->iso_frame_desc[i].offset = offs;
386 			urb->iso_frame_desc[i].length = ep->curpacksize;
387 			offs += ep->curpacksize;
388 		}
389 
390 		urb->transfer_buffer_length = offs;
391 		urb->number_of_packets = urb_ctx->packets;
392 		break;
393 
394 	case SND_USB_ENDPOINT_TYPE_SYNC:
395 		urb->iso_frame_desc[0].length = min(4u, ep->syncmaxsize);
396 		urb->iso_frame_desc[0].offset = 0;
397 		break;
398 	}
399 	return 0;
400 }
401 
402 /* notify an error as XRUN to the assigned PCM data substream */
403 static void notify_xrun(struct snd_usb_endpoint *ep)
404 {
405 	struct snd_usb_substream *data_subs;
406 	struct snd_pcm_substream *psubs;
407 
408 	data_subs = READ_ONCE(ep->data_subs);
409 	if (!data_subs)
410 		return;
411 	psubs = data_subs->pcm_substream;
412 	if (psubs && psubs->runtime &&
413 	    psubs->runtime->state == SNDRV_PCM_STATE_RUNNING)
414 		snd_pcm_stop_xrun(psubs);
415 }
416 
417 static struct snd_usb_packet_info *
418 next_packet_fifo_enqueue(struct snd_usb_endpoint *ep)
419 {
420 	struct snd_usb_packet_info *p;
421 
422 	p = ep->next_packet + (ep->next_packet_head + ep->next_packet_queued) %
423 		ARRAY_SIZE(ep->next_packet);
424 	ep->next_packet_queued++;
425 	return p;
426 }
427 
428 static struct snd_usb_packet_info *
429 next_packet_fifo_dequeue(struct snd_usb_endpoint *ep)
430 {
431 	struct snd_usb_packet_info *p;
432 
433 	p = ep->next_packet + ep->next_packet_head;
434 	ep->next_packet_head++;
435 	ep->next_packet_head %= ARRAY_SIZE(ep->next_packet);
436 	ep->next_packet_queued--;
437 	return p;
438 }
439 
440 static void push_back_to_ready_list(struct snd_usb_endpoint *ep,
441 				    struct snd_urb_ctx *ctx)
442 {
443 	unsigned long flags;
444 
445 	spin_lock_irqsave(&ep->lock, flags);
446 	list_add_tail(&ctx->ready_list, &ep->ready_playback_urbs);
447 	spin_unlock_irqrestore(&ep->lock, flags);
448 }
449 
450 /*
451  * Send output urbs that have been prepared previously. URBs are dequeued
452  * from ep->ready_playback_urbs and in case there aren't any available
453  * or there are no packets that have been prepared, this function does
454  * nothing.
455  *
456  * The reason why the functionality of sending and preparing URBs is separated
457  * is that host controllers don't guarantee the order in which they return
458  * inbound and outbound packets to their submitters.
459  *
460  * This function is used both for implicit feedback endpoints and in low-
461  * latency playback mode.
462  */
463 int snd_usb_queue_pending_output_urbs(struct snd_usb_endpoint *ep,
464 				      bool in_stream_lock)
465 {
466 	bool implicit_fb = snd_usb_endpoint_implicit_feedback_sink(ep);
467 
468 	while (ep_state_running(ep)) {
469 
470 		unsigned long flags;
471 		struct snd_usb_packet_info *packet;
472 		struct snd_urb_ctx *ctx = NULL;
473 		int err, i;
474 
475 		spin_lock_irqsave(&ep->lock, flags);
476 		if ((!implicit_fb || ep->next_packet_queued > 0) &&
477 		    !list_empty(&ep->ready_playback_urbs)) {
478 			/* take URB out of FIFO */
479 			ctx = list_first_entry(&ep->ready_playback_urbs,
480 					       struct snd_urb_ctx, ready_list);
481 			list_del_init(&ctx->ready_list);
482 			if (implicit_fb)
483 				packet = next_packet_fifo_dequeue(ep);
484 		}
485 		spin_unlock_irqrestore(&ep->lock, flags);
486 
487 		if (ctx == NULL)
488 			break;
489 
490 		/* copy over the length information */
491 		if (implicit_fb) {
492 			for (i = 0; i < packet->packets; i++)
493 				ctx->packet_size[i] = packet->packet_size[i];
494 		}
495 
496 		/* call the data handler to fill in playback data */
497 		err = prepare_outbound_urb(ep, ctx, in_stream_lock);
498 		/* can be stopped during prepare callback */
499 		if (unlikely(!ep_state_running(ep)))
500 			break;
501 		if (err < 0) {
502 			/* push back to ready list again for -EAGAIN */
503 			if (err == -EAGAIN) {
504 				push_back_to_ready_list(ep, ctx);
505 				break;
506 			}
507 
508 			if (!in_stream_lock)
509 				notify_xrun(ep);
510 			return -EPIPE;
511 		}
512 
513 		if (!atomic_read(&ep->chip->shutdown))
514 			err = usb_submit_urb(ctx->urb, GFP_ATOMIC);
515 		else
516 			err = -ENODEV;
517 		if (err < 0) {
518 			if (!atomic_read(&ep->chip->shutdown)) {
519 				usb_audio_err(ep->chip,
520 					      "Unable to submit urb #%d: %d at %s\n",
521 					      ctx->index, err, __func__);
522 				if (!in_stream_lock)
523 					notify_xrun(ep);
524 			}
525 			return -EPIPE;
526 		}
527 
528 		set_bit(ctx->index, &ep->active_mask);
529 		atomic_inc(&ep->submitted_urbs);
530 	}
531 
532 	return 0;
533 }
534 
535 /*
536  * complete callback for urbs
537  */
538 static void snd_complete_urb(struct urb *urb)
539 {
540 	struct snd_urb_ctx *ctx = urb->context;
541 	struct snd_usb_endpoint *ep = ctx->ep;
542 	int err;
543 
544 	if (unlikely(urb->status == -ENOENT ||		/* unlinked */
545 		     urb->status == -ENODEV ||		/* device removed */
546 		     urb->status == -ECONNRESET ||	/* unlinked */
547 		     urb->status == -ESHUTDOWN))	/* device disabled */
548 		goto exit_clear;
549 	/* device disconnected */
550 	if (unlikely(atomic_read(&ep->chip->shutdown)))
551 		goto exit_clear;
552 
553 	if (unlikely(!ep_state_running(ep)))
554 		goto exit_clear;
555 
556 	if (usb_pipeout(ep->pipe)) {
557 		retire_outbound_urb(ep, ctx);
558 		/* can be stopped during retire callback */
559 		if (unlikely(!ep_state_running(ep)))
560 			goto exit_clear;
561 
562 		/* in low-latency and implicit-feedback modes, push back the
563 		 * URB to ready list at first, then process as much as possible
564 		 */
565 		if (ep->lowlatency_playback ||
566 		     snd_usb_endpoint_implicit_feedback_sink(ep)) {
567 			push_back_to_ready_list(ep, ctx);
568 			clear_bit(ctx->index, &ep->active_mask);
569 			snd_usb_queue_pending_output_urbs(ep, false);
570 			/* decrement at last, and check xrun */
571 			if (atomic_dec_and_test(&ep->submitted_urbs) &&
572 			    !snd_usb_endpoint_implicit_feedback_sink(ep))
573 				notify_xrun(ep);
574 			return;
575 		}
576 
577 		/* in non-lowlatency mode, no error handling for prepare */
578 		prepare_outbound_urb(ep, ctx, false);
579 		/* can be stopped during prepare callback */
580 		if (unlikely(!ep_state_running(ep)))
581 			goto exit_clear;
582 	} else {
583 		retire_inbound_urb(ep, ctx);
584 		/* can be stopped during retire callback */
585 		if (unlikely(!ep_state_running(ep)))
586 			goto exit_clear;
587 
588 		prepare_inbound_urb(ep, ctx);
589 	}
590 
591 	if (!atomic_read(&ep->chip->shutdown))
592 		err = usb_submit_urb(urb, GFP_ATOMIC);
593 	else
594 		err = -ENODEV;
595 	if (err == 0)
596 		return;
597 
598 	if (!atomic_read(&ep->chip->shutdown)) {
599 		usb_audio_err(ep->chip, "cannot submit urb (err = %d)\n", err);
600 		notify_xrun(ep);
601 	}
602 
603 exit_clear:
604 	clear_bit(ctx->index, &ep->active_mask);
605 	atomic_dec(&ep->submitted_urbs);
606 }
607 
608 /*
609  * Find or create a refcount object for the given interface
610  *
611  * The objects are released altogether in snd_usb_endpoint_free_all()
612  */
613 static struct snd_usb_iface_ref *
614 iface_ref_find(struct snd_usb_audio *chip, int iface)
615 {
616 	struct snd_usb_iface_ref *ip;
617 
618 	list_for_each_entry(ip, &chip->iface_ref_list, list)
619 		if (ip->iface == iface)
620 			return ip;
621 
622 	ip = kzalloc(sizeof(*ip), GFP_KERNEL);
623 	if (!ip)
624 		return NULL;
625 	ip->iface = iface;
626 	list_add_tail(&ip->list, &chip->iface_ref_list);
627 	return ip;
628 }
629 
630 /* Similarly, a refcount object for clock */
631 static struct snd_usb_clock_ref *
632 clock_ref_find(struct snd_usb_audio *chip, int clock)
633 {
634 	struct snd_usb_clock_ref *ref;
635 
636 	list_for_each_entry(ref, &chip->clock_ref_list, list)
637 		if (ref->clock == clock)
638 			return ref;
639 
640 	ref = kzalloc(sizeof(*ref), GFP_KERNEL);
641 	if (!ref)
642 		return NULL;
643 	ref->clock = clock;
644 	atomic_set(&ref->locked, 0);
645 	list_add_tail(&ref->list, &chip->clock_ref_list);
646 	return ref;
647 }
648 
649 /*
650  * Get the existing endpoint object corresponding EP
651  * Returns NULL if not present.
652  */
653 struct snd_usb_endpoint *
654 snd_usb_get_endpoint(struct snd_usb_audio *chip, int ep_num)
655 {
656 	struct snd_usb_endpoint *ep;
657 
658 	list_for_each_entry(ep, &chip->ep_list, list) {
659 		if (ep->ep_num == ep_num)
660 			return ep;
661 	}
662 
663 	return NULL;
664 }
665 
666 #define ep_type_name(type) \
667 	(type == SND_USB_ENDPOINT_TYPE_DATA ? "data" : "sync")
668 
669 /**
670  * snd_usb_add_endpoint: Add an endpoint to an USB audio chip
671  *
672  * @chip: The chip
673  * @ep_num: The number of the endpoint to use
674  * @type: SND_USB_ENDPOINT_TYPE_DATA or SND_USB_ENDPOINT_TYPE_SYNC
675  *
676  * If the requested endpoint has not been added to the given chip before,
677  * a new instance is created.
678  *
679  * Returns zero on success or a negative error code.
680  *
681  * New endpoints will be added to chip->ep_list and freed by
682  * calling snd_usb_endpoint_free_all().
683  *
684  * For SND_USB_ENDPOINT_TYPE_SYNC, the caller needs to guarantee that
685  * bNumEndpoints > 1 beforehand.
686  */
687 int snd_usb_add_endpoint(struct snd_usb_audio *chip, int ep_num, int type)
688 {
689 	struct snd_usb_endpoint *ep;
690 	bool is_playback;
691 
692 	ep = snd_usb_get_endpoint(chip, ep_num);
693 	if (ep)
694 		return 0;
695 
696 	usb_audio_dbg(chip, "Creating new %s endpoint #%x\n",
697 		      ep_type_name(type),
698 		      ep_num);
699 	ep = kzalloc(sizeof(*ep), GFP_KERNEL);
700 	if (!ep)
701 		return -ENOMEM;
702 
703 	ep->chip = chip;
704 	spin_lock_init(&ep->lock);
705 	ep->type = type;
706 	ep->ep_num = ep_num;
707 	INIT_LIST_HEAD(&ep->ready_playback_urbs);
708 	atomic_set(&ep->submitted_urbs, 0);
709 
710 	is_playback = ((ep_num & USB_ENDPOINT_DIR_MASK) == USB_DIR_OUT);
711 	ep_num &= USB_ENDPOINT_NUMBER_MASK;
712 	if (is_playback)
713 		ep->pipe = usb_sndisocpipe(chip->dev, ep_num);
714 	else
715 		ep->pipe = usb_rcvisocpipe(chip->dev, ep_num);
716 
717 	list_add_tail(&ep->list, &chip->ep_list);
718 	return 0;
719 }
720 
721 /* Set up syncinterval and maxsyncsize for a sync EP */
722 static void endpoint_set_syncinterval(struct snd_usb_audio *chip,
723 				      struct snd_usb_endpoint *ep)
724 {
725 	struct usb_host_interface *alts;
726 	struct usb_endpoint_descriptor *desc;
727 
728 	alts = snd_usb_get_host_interface(chip, ep->iface, ep->altsetting);
729 	if (!alts)
730 		return;
731 
732 	desc = get_endpoint(alts, ep->ep_idx);
733 	if (desc->bLength >= USB_DT_ENDPOINT_AUDIO_SIZE &&
734 	    desc->bRefresh >= 1 && desc->bRefresh <= 9)
735 		ep->syncinterval = desc->bRefresh;
736 	else if (snd_usb_get_speed(chip->dev) == USB_SPEED_FULL)
737 		ep->syncinterval = 1;
738 	else if (desc->bInterval >= 1 && desc->bInterval <= 16)
739 		ep->syncinterval = desc->bInterval - 1;
740 	else
741 		ep->syncinterval = 3;
742 
743 	ep->syncmaxsize = le16_to_cpu(desc->wMaxPacketSize);
744 }
745 
746 static bool endpoint_compatible(struct snd_usb_endpoint *ep,
747 				const struct audioformat *fp,
748 				const struct snd_pcm_hw_params *params)
749 {
750 	if (!ep->opened)
751 		return false;
752 	if (ep->cur_audiofmt != fp)
753 		return false;
754 	if (ep->cur_rate != params_rate(params) ||
755 	    ep->cur_format != params_format(params) ||
756 	    ep->cur_period_frames != params_period_size(params) ||
757 	    ep->cur_buffer_periods != params_periods(params))
758 		return false;
759 	return true;
760 }
761 
762 /*
763  * Check whether the given fp and hw params are compatible with the current
764  * setup of the target EP for implicit feedback sync
765  */
766 bool snd_usb_endpoint_compatible(struct snd_usb_audio *chip,
767 				 struct snd_usb_endpoint *ep,
768 				 const struct audioformat *fp,
769 				 const struct snd_pcm_hw_params *params)
770 {
771 	bool ret;
772 
773 	mutex_lock(&chip->mutex);
774 	ret = endpoint_compatible(ep, fp, params);
775 	mutex_unlock(&chip->mutex);
776 	return ret;
777 }
778 
779 /*
780  * snd_usb_endpoint_open: Open the endpoint
781  *
782  * Called from hw_params to assign the endpoint to the substream.
783  * It's reference-counted, and only the first opener is allowed to set up
784  * arbitrary parameters.  The later opener must be compatible with the
785  * former opened parameters.
786  * The endpoint needs to be closed via snd_usb_endpoint_close() later.
787  *
788  * Note that this function doesn't configure the endpoint.  The substream
789  * needs to set it up later via snd_usb_endpoint_set_params() and
790  * snd_usb_endpoint_prepare().
791  */
792 struct snd_usb_endpoint *
793 snd_usb_endpoint_open(struct snd_usb_audio *chip,
794 		      const struct audioformat *fp,
795 		      const struct snd_pcm_hw_params *params,
796 		      bool is_sync_ep,
797 		      bool fixed_rate)
798 {
799 	struct snd_usb_endpoint *ep;
800 	int ep_num = is_sync_ep ? fp->sync_ep : fp->endpoint;
801 
802 	mutex_lock(&chip->mutex);
803 	ep = snd_usb_get_endpoint(chip, ep_num);
804 	if (!ep) {
805 		usb_audio_err(chip, "Cannot find EP 0x%x to open\n", ep_num);
806 		goto unlock;
807 	}
808 
809 	if (!ep->opened) {
810 		if (is_sync_ep) {
811 			ep->iface = fp->sync_iface;
812 			ep->altsetting = fp->sync_altsetting;
813 			ep->ep_idx = fp->sync_ep_idx;
814 		} else {
815 			ep->iface = fp->iface;
816 			ep->altsetting = fp->altsetting;
817 			ep->ep_idx = fp->ep_idx;
818 		}
819 		usb_audio_dbg(chip, "Open EP 0x%x, iface=%d:%d, idx=%d\n",
820 			      ep_num, ep->iface, ep->altsetting, ep->ep_idx);
821 
822 		ep->iface_ref = iface_ref_find(chip, ep->iface);
823 		if (!ep->iface_ref) {
824 			ep = NULL;
825 			goto unlock;
826 		}
827 
828 		if (fp->protocol != UAC_VERSION_1) {
829 			ep->clock_ref = clock_ref_find(chip, fp->clock);
830 			if (!ep->clock_ref) {
831 				ep = NULL;
832 				goto unlock;
833 			}
834 			ep->clock_ref->opened++;
835 		}
836 
837 		ep->cur_audiofmt = fp;
838 		ep->cur_channels = fp->channels;
839 		ep->cur_rate = params_rate(params);
840 		ep->cur_format = params_format(params);
841 		ep->cur_frame_bytes = snd_pcm_format_physical_width(ep->cur_format) *
842 			ep->cur_channels / 8;
843 		ep->cur_period_frames = params_period_size(params);
844 		ep->cur_period_bytes = ep->cur_period_frames * ep->cur_frame_bytes;
845 		ep->cur_buffer_periods = params_periods(params);
846 
847 		if (ep->type == SND_USB_ENDPOINT_TYPE_SYNC)
848 			endpoint_set_syncinterval(chip, ep);
849 
850 		ep->implicit_fb_sync = fp->implicit_fb;
851 		ep->need_setup = true;
852 		ep->need_prepare = true;
853 		ep->fixed_rate = fixed_rate;
854 
855 		usb_audio_dbg(chip, "  channels=%d, rate=%d, format=%s, period_bytes=%d, periods=%d, implicit_fb=%d\n",
856 			      ep->cur_channels, ep->cur_rate,
857 			      snd_pcm_format_name(ep->cur_format),
858 			      ep->cur_period_bytes, ep->cur_buffer_periods,
859 			      ep->implicit_fb_sync);
860 
861 	} else {
862 		if (WARN_ON(!ep->iface_ref)) {
863 			ep = NULL;
864 			goto unlock;
865 		}
866 
867 		if (!endpoint_compatible(ep, fp, params)) {
868 			usb_audio_err(chip, "Incompatible EP setup for 0x%x\n",
869 				      ep_num);
870 			ep = NULL;
871 			goto unlock;
872 		}
873 
874 		usb_audio_dbg(chip, "Reopened EP 0x%x (count %d)\n",
875 			      ep_num, ep->opened);
876 	}
877 
878 	if (!ep->iface_ref->opened++)
879 		ep->iface_ref->need_setup = true;
880 
881 	ep->opened++;
882 
883  unlock:
884 	mutex_unlock(&chip->mutex);
885 	return ep;
886 }
887 
888 /*
889  * snd_usb_endpoint_set_sync: Link data and sync endpoints
890  *
891  * Pass NULL to sync_ep to unlink again
892  */
893 void snd_usb_endpoint_set_sync(struct snd_usb_audio *chip,
894 			       struct snd_usb_endpoint *data_ep,
895 			       struct snd_usb_endpoint *sync_ep)
896 {
897 	data_ep->sync_source = sync_ep;
898 }
899 
900 /*
901  * Set data endpoint callbacks and the assigned data stream
902  *
903  * Called at PCM trigger and cleanups.
904  * Pass NULL to deactivate each callback.
905  */
906 void snd_usb_endpoint_set_callback(struct snd_usb_endpoint *ep,
907 				   int (*prepare)(struct snd_usb_substream *subs,
908 						  struct urb *urb,
909 						  bool in_stream_lock),
910 				   void (*retire)(struct snd_usb_substream *subs,
911 						  struct urb *urb),
912 				   struct snd_usb_substream *data_subs)
913 {
914 	ep->prepare_data_urb = prepare;
915 	ep->retire_data_urb = retire;
916 	if (data_subs)
917 		ep->lowlatency_playback = data_subs->lowlatency_playback;
918 	else
919 		ep->lowlatency_playback = false;
920 	WRITE_ONCE(ep->data_subs, data_subs);
921 }
922 
923 static int endpoint_set_interface(struct snd_usb_audio *chip,
924 				  struct snd_usb_endpoint *ep,
925 				  bool set)
926 {
927 	int altset = set ? ep->altsetting : 0;
928 	int err;
929 
930 	if (ep->iface_ref->altset == altset)
931 		return 0;
932 	/* already disconnected? */
933 	if (unlikely(atomic_read(&chip->shutdown)))
934 		return -ENODEV;
935 
936 	usb_audio_dbg(chip, "Setting usb interface %d:%d for EP 0x%x\n",
937 		      ep->iface, altset, ep->ep_num);
938 	err = usb_set_interface(chip->dev, ep->iface, altset);
939 	if (err < 0) {
940 		usb_audio_err_ratelimited(
941 			chip, "%d:%d: usb_set_interface failed (%d)\n",
942 			ep->iface, altset, err);
943 		return err;
944 	}
945 
946 	if (chip->quirk_flags & QUIRK_FLAG_IFACE_DELAY)
947 		msleep(50);
948 	ep->iface_ref->altset = altset;
949 	return 0;
950 }
951 
952 /*
953  * snd_usb_endpoint_close: Close the endpoint
954  *
955  * Unreference the already opened endpoint via snd_usb_endpoint_open().
956  */
957 void snd_usb_endpoint_close(struct snd_usb_audio *chip,
958 			    struct snd_usb_endpoint *ep)
959 {
960 	mutex_lock(&chip->mutex);
961 	usb_audio_dbg(chip, "Closing EP 0x%x (count %d)\n",
962 		      ep->ep_num, ep->opened);
963 
964 	if (!--ep->iface_ref->opened &&
965 		!(chip->quirk_flags & QUIRK_FLAG_IFACE_SKIP_CLOSE))
966 		endpoint_set_interface(chip, ep, false);
967 
968 	if (!--ep->opened) {
969 		if (ep->clock_ref) {
970 			if (!--ep->clock_ref->opened)
971 				ep->clock_ref->rate = 0;
972 		}
973 		ep->iface = 0;
974 		ep->altsetting = 0;
975 		ep->cur_audiofmt = NULL;
976 		ep->cur_rate = 0;
977 		ep->iface_ref = NULL;
978 		ep->clock_ref = NULL;
979 		usb_audio_dbg(chip, "EP 0x%x closed\n", ep->ep_num);
980 	}
981 	mutex_unlock(&chip->mutex);
982 }
983 
984 /* Prepare for suspening EP, called from the main suspend handler */
985 void snd_usb_endpoint_suspend(struct snd_usb_endpoint *ep)
986 {
987 	ep->need_prepare = true;
988 	if (ep->iface_ref)
989 		ep->iface_ref->need_setup = true;
990 	if (ep->clock_ref)
991 		ep->clock_ref->rate = 0;
992 }
993 
994 /*
995  *  wait until all urbs are processed.
996  */
997 static int wait_clear_urbs(struct snd_usb_endpoint *ep)
998 {
999 	unsigned long end_time = jiffies + msecs_to_jiffies(1000);
1000 	int alive;
1001 
1002 	if (atomic_read(&ep->state) != EP_STATE_STOPPING)
1003 		return 0;
1004 
1005 	do {
1006 		alive = atomic_read(&ep->submitted_urbs);
1007 		if (!alive)
1008 			break;
1009 
1010 		schedule_timeout_uninterruptible(1);
1011 	} while (time_before(jiffies, end_time));
1012 
1013 	if (alive)
1014 		usb_audio_err(ep->chip,
1015 			"timeout: still %d active urbs on EP #%x\n",
1016 			alive, ep->ep_num);
1017 
1018 	if (ep_state_update(ep, EP_STATE_STOPPING, EP_STATE_STOPPED)) {
1019 		ep->sync_sink = NULL;
1020 		snd_usb_endpoint_set_callback(ep, NULL, NULL, NULL);
1021 	}
1022 
1023 	return 0;
1024 }
1025 
1026 /* sync the pending stop operation;
1027  * this function itself doesn't trigger the stop operation
1028  */
1029 void snd_usb_endpoint_sync_pending_stop(struct snd_usb_endpoint *ep)
1030 {
1031 	if (ep)
1032 		wait_clear_urbs(ep);
1033 }
1034 
1035 /*
1036  * Stop active urbs
1037  *
1038  * This function moves the EP to STOPPING state if it's being RUNNING.
1039  */
1040 static int stop_urbs(struct snd_usb_endpoint *ep, bool force, bool keep_pending)
1041 {
1042 	unsigned int i;
1043 	unsigned long flags;
1044 
1045 	if (!force && atomic_read(&ep->running))
1046 		return -EBUSY;
1047 
1048 	if (!ep_state_update(ep, EP_STATE_RUNNING, EP_STATE_STOPPING))
1049 		return 0;
1050 
1051 	spin_lock_irqsave(&ep->lock, flags);
1052 	INIT_LIST_HEAD(&ep->ready_playback_urbs);
1053 	ep->next_packet_head = 0;
1054 	ep->next_packet_queued = 0;
1055 	spin_unlock_irqrestore(&ep->lock, flags);
1056 
1057 	if (keep_pending)
1058 		return 0;
1059 
1060 	for (i = 0; i < ep->nurbs; i++) {
1061 		if (test_bit(i, &ep->active_mask)) {
1062 			if (!test_and_set_bit(i, &ep->unlink_mask)) {
1063 				struct urb *u = ep->urb[i].urb;
1064 				usb_unlink_urb(u);
1065 			}
1066 		}
1067 	}
1068 
1069 	return 0;
1070 }
1071 
1072 /*
1073  * release an endpoint's urbs
1074  */
1075 static int release_urbs(struct snd_usb_endpoint *ep, bool force)
1076 {
1077 	int i, err;
1078 
1079 	/* route incoming urbs to nirvana */
1080 	snd_usb_endpoint_set_callback(ep, NULL, NULL, NULL);
1081 
1082 	/* stop and unlink urbs */
1083 	err = stop_urbs(ep, force, false);
1084 	if (err)
1085 		return err;
1086 
1087 	wait_clear_urbs(ep);
1088 
1089 	for (i = 0; i < ep->nurbs; i++)
1090 		release_urb_ctx(&ep->urb[i]);
1091 
1092 	usb_free_coherent(ep->chip->dev, SYNC_URBS * 4,
1093 			  ep->syncbuf, ep->sync_dma);
1094 
1095 	ep->syncbuf = NULL;
1096 	ep->nurbs = 0;
1097 	return 0;
1098 }
1099 
1100 /*
1101  * configure a data endpoint
1102  */
1103 static int data_ep_set_params(struct snd_usb_endpoint *ep)
1104 {
1105 	struct snd_usb_audio *chip = ep->chip;
1106 	unsigned int maxsize, minsize, packs_per_ms, max_packs_per_urb;
1107 	unsigned int max_packs_per_period, urbs_per_period, urb_packs;
1108 	unsigned int max_urbs, i;
1109 	const struct audioformat *fmt = ep->cur_audiofmt;
1110 	int frame_bits = ep->cur_frame_bytes * 8;
1111 	int tx_length_quirk = (has_tx_length_quirk(chip) &&
1112 			       usb_pipeout(ep->pipe));
1113 
1114 	usb_audio_dbg(chip, "Setting params for data EP 0x%x, pipe 0x%x\n",
1115 		      ep->ep_num, ep->pipe);
1116 
1117 	if (ep->cur_format == SNDRV_PCM_FORMAT_DSD_U16_LE && fmt->dsd_dop) {
1118 		/*
1119 		 * When operating in DSD DOP mode, the size of a sample frame
1120 		 * in hardware differs from the actual physical format width
1121 		 * because we need to make room for the DOP markers.
1122 		 */
1123 		frame_bits += ep->cur_channels << 3;
1124 	}
1125 
1126 	ep->datainterval = fmt->datainterval;
1127 	ep->stride = frame_bits >> 3;
1128 
1129 	switch (ep->cur_format) {
1130 	case SNDRV_PCM_FORMAT_U8:
1131 		ep->silence_value = 0x80;
1132 		break;
1133 	case SNDRV_PCM_FORMAT_DSD_U8:
1134 	case SNDRV_PCM_FORMAT_DSD_U16_LE:
1135 	case SNDRV_PCM_FORMAT_DSD_U32_LE:
1136 	case SNDRV_PCM_FORMAT_DSD_U16_BE:
1137 	case SNDRV_PCM_FORMAT_DSD_U32_BE:
1138 		ep->silence_value = 0x69;
1139 		break;
1140 	default:
1141 		ep->silence_value = 0;
1142 	}
1143 
1144 	/* assume max. frequency is 50% higher than nominal */
1145 	ep->freqmax = ep->freqn + (ep->freqn >> 1);
1146 	/* Round up freqmax to nearest integer in order to calculate maximum
1147 	 * packet size, which must represent a whole number of frames.
1148 	 * This is accomplished by adding 0x0.ffff before converting the
1149 	 * Q16.16 format into integer.
1150 	 * In order to accurately calculate the maximum packet size when
1151 	 * the data interval is more than 1 (i.e. ep->datainterval > 0),
1152 	 * multiply by the data interval prior to rounding. For instance,
1153 	 * a freqmax of 41 kHz will result in a max packet size of 6 (5.125)
1154 	 * frames with a data interval of 1, but 11 (10.25) frames with a
1155 	 * data interval of 2.
1156 	 * (ep->freqmax << ep->datainterval overflows at 8.192 MHz for the
1157 	 * maximum datainterval value of 3, at USB full speed, higher for
1158 	 * USB high speed, noting that ep->freqmax is in units of
1159 	 * frames per packet in Q16.16 format.)
1160 	 */
1161 	maxsize = (((ep->freqmax << ep->datainterval) + 0xffff) >> 16) *
1162 			 (frame_bits >> 3);
1163 	if (tx_length_quirk)
1164 		maxsize += sizeof(__le32); /* Space for length descriptor */
1165 	/* but wMaxPacketSize might reduce this */
1166 	if (ep->maxpacksize && ep->maxpacksize < maxsize) {
1167 		/* whatever fits into a max. size packet */
1168 		unsigned int data_maxsize = maxsize = ep->maxpacksize;
1169 
1170 		if (tx_length_quirk)
1171 			/* Need to remove the length descriptor to calc freq */
1172 			data_maxsize -= sizeof(__le32);
1173 		ep->freqmax = (data_maxsize / (frame_bits >> 3))
1174 				<< (16 - ep->datainterval);
1175 	}
1176 
1177 	if (ep->fill_max)
1178 		ep->curpacksize = ep->maxpacksize;
1179 	else
1180 		ep->curpacksize = maxsize;
1181 
1182 	if (snd_usb_get_speed(chip->dev) != USB_SPEED_FULL) {
1183 		packs_per_ms = 8 >> ep->datainterval;
1184 		max_packs_per_urb = MAX_PACKS_HS;
1185 	} else {
1186 		packs_per_ms = 1;
1187 		max_packs_per_urb = MAX_PACKS;
1188 	}
1189 	if (ep->sync_source && !ep->implicit_fb_sync)
1190 		max_packs_per_urb = min(max_packs_per_urb,
1191 					1U << ep->sync_source->syncinterval);
1192 	max_packs_per_urb = max(1u, max_packs_per_urb >> ep->datainterval);
1193 
1194 	/*
1195 	 * Capture endpoints need to use small URBs because there's no way
1196 	 * to tell in advance where the next period will end, and we don't
1197 	 * want the next URB to complete much after the period ends.
1198 	 *
1199 	 * Playback endpoints with implicit sync much use the same parameters
1200 	 * as their corresponding capture endpoint.
1201 	 */
1202 	if (usb_pipein(ep->pipe) || ep->implicit_fb_sync) {
1203 
1204 		/* make capture URBs <= 1 ms and smaller than a period */
1205 		urb_packs = min(max_packs_per_urb, packs_per_ms);
1206 		while (urb_packs > 1 && urb_packs * maxsize >= ep->cur_period_bytes)
1207 			urb_packs >>= 1;
1208 		ep->nurbs = MAX_URBS;
1209 
1210 	/*
1211 	 * Playback endpoints without implicit sync are adjusted so that
1212 	 * a period fits as evenly as possible in the smallest number of
1213 	 * URBs.  The total number of URBs is adjusted to the size of the
1214 	 * ALSA buffer, subject to the MAX_URBS and MAX_QUEUE limits.
1215 	 */
1216 	} else {
1217 		/* determine how small a packet can be */
1218 		minsize = (ep->freqn >> (16 - ep->datainterval)) *
1219 				(frame_bits >> 3);
1220 		/* with sync from device, assume it can be 12% lower */
1221 		if (ep->sync_source)
1222 			minsize -= minsize >> 3;
1223 		minsize = max(minsize, 1u);
1224 
1225 		/* how many packets will contain an entire ALSA period? */
1226 		max_packs_per_period = DIV_ROUND_UP(ep->cur_period_bytes, minsize);
1227 
1228 		/* how many URBs will contain a period? */
1229 		urbs_per_period = DIV_ROUND_UP(max_packs_per_period,
1230 				max_packs_per_urb);
1231 		/* how many packets are needed in each URB? */
1232 		urb_packs = DIV_ROUND_UP(max_packs_per_period, urbs_per_period);
1233 
1234 		/* limit the number of frames in a single URB */
1235 		ep->max_urb_frames = DIV_ROUND_UP(ep->cur_period_frames,
1236 						  urbs_per_period);
1237 
1238 		/* try to use enough URBs to contain an entire ALSA buffer */
1239 		max_urbs = min((unsigned) MAX_URBS,
1240 				MAX_QUEUE * packs_per_ms / urb_packs);
1241 		ep->nurbs = min(max_urbs, urbs_per_period * ep->cur_buffer_periods);
1242 	}
1243 
1244 	/* allocate and initialize data urbs */
1245 	for (i = 0; i < ep->nurbs; i++) {
1246 		struct snd_urb_ctx *u = &ep->urb[i];
1247 		u->index = i;
1248 		u->ep = ep;
1249 		u->packets = urb_packs;
1250 		u->buffer_size = maxsize * u->packets;
1251 
1252 		if (fmt->fmt_type == UAC_FORMAT_TYPE_II)
1253 			u->packets++; /* for transfer delimiter */
1254 		u->urb = usb_alloc_urb(u->packets, GFP_KERNEL);
1255 		if (!u->urb)
1256 			goto out_of_memory;
1257 
1258 		u->urb->transfer_buffer =
1259 			usb_alloc_coherent(chip->dev, u->buffer_size,
1260 					   GFP_KERNEL, &u->urb->transfer_dma);
1261 		if (!u->urb->transfer_buffer)
1262 			goto out_of_memory;
1263 		u->urb->pipe = ep->pipe;
1264 		u->urb->transfer_flags = URB_NO_TRANSFER_DMA_MAP;
1265 		u->urb->interval = 1 << ep->datainterval;
1266 		u->urb->context = u;
1267 		u->urb->complete = snd_complete_urb;
1268 		INIT_LIST_HEAD(&u->ready_list);
1269 	}
1270 
1271 	return 0;
1272 
1273 out_of_memory:
1274 	release_urbs(ep, false);
1275 	return -ENOMEM;
1276 }
1277 
1278 /*
1279  * configure a sync endpoint
1280  */
1281 static int sync_ep_set_params(struct snd_usb_endpoint *ep)
1282 {
1283 	struct snd_usb_audio *chip = ep->chip;
1284 	int i;
1285 
1286 	usb_audio_dbg(chip, "Setting params for sync EP 0x%x, pipe 0x%x\n",
1287 		      ep->ep_num, ep->pipe);
1288 
1289 	ep->syncbuf = usb_alloc_coherent(chip->dev, SYNC_URBS * 4,
1290 					 GFP_KERNEL, &ep->sync_dma);
1291 	if (!ep->syncbuf)
1292 		return -ENOMEM;
1293 
1294 	ep->nurbs = SYNC_URBS;
1295 	for (i = 0; i < SYNC_URBS; i++) {
1296 		struct snd_urb_ctx *u = &ep->urb[i];
1297 		u->index = i;
1298 		u->ep = ep;
1299 		u->packets = 1;
1300 		u->urb = usb_alloc_urb(1, GFP_KERNEL);
1301 		if (!u->urb)
1302 			goto out_of_memory;
1303 		u->urb->transfer_buffer = ep->syncbuf + i * 4;
1304 		u->urb->transfer_dma = ep->sync_dma + i * 4;
1305 		u->urb->transfer_buffer_length = 4;
1306 		u->urb->pipe = ep->pipe;
1307 		u->urb->transfer_flags = URB_NO_TRANSFER_DMA_MAP;
1308 		u->urb->number_of_packets = 1;
1309 		u->urb->interval = 1 << ep->syncinterval;
1310 		u->urb->context = u;
1311 		u->urb->complete = snd_complete_urb;
1312 	}
1313 
1314 	return 0;
1315 
1316 out_of_memory:
1317 	release_urbs(ep, false);
1318 	return -ENOMEM;
1319 }
1320 
1321 /* update the rate of the referred clock; return the actual rate */
1322 static int update_clock_ref_rate(struct snd_usb_audio *chip,
1323 				 struct snd_usb_endpoint *ep)
1324 {
1325 	struct snd_usb_clock_ref *clock = ep->clock_ref;
1326 	int rate = ep->cur_rate;
1327 
1328 	if (!clock || clock->rate == rate)
1329 		return rate;
1330 	if (clock->rate) {
1331 		if (atomic_read(&clock->locked))
1332 			return clock->rate;
1333 		if (clock->rate != rate) {
1334 			usb_audio_err(chip, "Mismatched sample rate %d vs %d for EP 0x%x\n",
1335 				      clock->rate, rate, ep->ep_num);
1336 			return clock->rate;
1337 		}
1338 	}
1339 	clock->rate = rate;
1340 	clock->need_setup = true;
1341 	return rate;
1342 }
1343 
1344 /*
1345  * snd_usb_endpoint_set_params: configure an snd_usb_endpoint
1346  *
1347  * It's called either from hw_params callback.
1348  * Determine the number of URBs to be used on this endpoint.
1349  * An endpoint must be configured before it can be started.
1350  * An endpoint that is already running can not be reconfigured.
1351  */
1352 int snd_usb_endpoint_set_params(struct snd_usb_audio *chip,
1353 				struct snd_usb_endpoint *ep)
1354 {
1355 	const struct audioformat *fmt = ep->cur_audiofmt;
1356 	int err = 0;
1357 
1358 	mutex_lock(&chip->mutex);
1359 	if (!ep->need_setup)
1360 		goto unlock;
1361 
1362 	/* release old buffers, if any */
1363 	err = release_urbs(ep, false);
1364 	if (err < 0)
1365 		goto unlock;
1366 
1367 	ep->datainterval = fmt->datainterval;
1368 	ep->maxpacksize = fmt->maxpacksize;
1369 	ep->fill_max = !!(fmt->attributes & UAC_EP_CS_ATTR_FILL_MAX);
1370 
1371 	if (snd_usb_get_speed(chip->dev) == USB_SPEED_FULL) {
1372 		ep->freqn = get_usb_full_speed_rate(ep->cur_rate);
1373 		ep->pps = 1000 >> ep->datainterval;
1374 	} else {
1375 		ep->freqn = get_usb_high_speed_rate(ep->cur_rate);
1376 		ep->pps = 8000 >> ep->datainterval;
1377 	}
1378 
1379 	ep->sample_rem = ep->cur_rate % ep->pps;
1380 	ep->packsize[0] = ep->cur_rate / ep->pps;
1381 	ep->packsize[1] = (ep->cur_rate + (ep->pps - 1)) / ep->pps;
1382 
1383 	/* calculate the frequency in 16.16 format */
1384 	ep->freqm = ep->freqn;
1385 	ep->freqshift = INT_MIN;
1386 
1387 	ep->phase = 0;
1388 
1389 	switch (ep->type) {
1390 	case  SND_USB_ENDPOINT_TYPE_DATA:
1391 		err = data_ep_set_params(ep);
1392 		break;
1393 	case  SND_USB_ENDPOINT_TYPE_SYNC:
1394 		err = sync_ep_set_params(ep);
1395 		break;
1396 	default:
1397 		err = -EINVAL;
1398 	}
1399 
1400 	usb_audio_dbg(chip, "Set up %d URBS, ret=%d\n", ep->nurbs, err);
1401 
1402 	if (err < 0)
1403 		goto unlock;
1404 
1405 	/* some unit conversions in runtime */
1406 	ep->maxframesize = ep->maxpacksize / ep->cur_frame_bytes;
1407 	ep->curframesize = ep->curpacksize / ep->cur_frame_bytes;
1408 
1409 	err = update_clock_ref_rate(chip, ep);
1410 	if (err >= 0) {
1411 		ep->need_setup = false;
1412 		err = 0;
1413 	}
1414 
1415  unlock:
1416 	mutex_unlock(&chip->mutex);
1417 	return err;
1418 }
1419 
1420 static int init_sample_rate(struct snd_usb_audio *chip,
1421 			    struct snd_usb_endpoint *ep)
1422 {
1423 	struct snd_usb_clock_ref *clock = ep->clock_ref;
1424 	int rate, err;
1425 
1426 	rate = update_clock_ref_rate(chip, ep);
1427 	if (rate < 0)
1428 		return rate;
1429 	if (clock && !clock->need_setup)
1430 		return 0;
1431 
1432 	if (!ep->fixed_rate) {
1433 		err = snd_usb_init_sample_rate(chip, ep->cur_audiofmt, rate);
1434 		if (err < 0) {
1435 			if (clock)
1436 				clock->rate = 0; /* reset rate */
1437 			return err;
1438 		}
1439 	}
1440 
1441 	if (clock)
1442 		clock->need_setup = false;
1443 	return 0;
1444 }
1445 
1446 /*
1447  * snd_usb_endpoint_prepare: Prepare the endpoint
1448  *
1449  * This function sets up the EP to be fully usable state.
1450  * It's called either from prepare callback.
1451  * The function checks need_setup flag, and performs nothing unless needed,
1452  * so it's safe to call this multiple times.
1453  *
1454  * This returns zero if unchanged, 1 if the configuration has changed,
1455  * or a negative error code.
1456  */
1457 int snd_usb_endpoint_prepare(struct snd_usb_audio *chip,
1458 			     struct snd_usb_endpoint *ep)
1459 {
1460 	bool iface_first;
1461 	int err = 0;
1462 
1463 	mutex_lock(&chip->mutex);
1464 	if (WARN_ON(!ep->iface_ref))
1465 		goto unlock;
1466 	if (!ep->need_prepare)
1467 		goto unlock;
1468 
1469 	/* If the interface has been already set up, just set EP parameters */
1470 	if (!ep->iface_ref->need_setup) {
1471 		/* sample rate setup of UAC1 is per endpoint, and we need
1472 		 * to update at each EP configuration
1473 		 */
1474 		if (ep->cur_audiofmt->protocol == UAC_VERSION_1) {
1475 			err = init_sample_rate(chip, ep);
1476 			if (err < 0)
1477 				goto unlock;
1478 		}
1479 		goto done;
1480 	}
1481 
1482 	/* Need to deselect altsetting at first */
1483 	endpoint_set_interface(chip, ep, false);
1484 
1485 	/* Some UAC1 devices (e.g. Yamaha THR10) need the host interface
1486 	 * to be set up before parameter setups
1487 	 */
1488 	iface_first = ep->cur_audiofmt->protocol == UAC_VERSION_1;
1489 	/* Workaround for devices that require the interface setup at first like UAC1 */
1490 	if (chip->quirk_flags & QUIRK_FLAG_SET_IFACE_FIRST)
1491 		iface_first = true;
1492 	if (iface_first) {
1493 		err = endpoint_set_interface(chip, ep, true);
1494 		if (err < 0)
1495 			goto unlock;
1496 	}
1497 
1498 	err = snd_usb_init_pitch(chip, ep->cur_audiofmt);
1499 	if (err < 0)
1500 		goto unlock;
1501 
1502 	err = init_sample_rate(chip, ep);
1503 	if (err < 0)
1504 		goto unlock;
1505 
1506 	err = snd_usb_select_mode_quirk(chip, ep->cur_audiofmt);
1507 	if (err < 0)
1508 		goto unlock;
1509 
1510 	/* for UAC2/3, enable the interface altset here at last */
1511 	if (!iface_first) {
1512 		err = endpoint_set_interface(chip, ep, true);
1513 		if (err < 0)
1514 			goto unlock;
1515 	}
1516 
1517 	ep->iface_ref->need_setup = false;
1518 
1519  done:
1520 	ep->need_prepare = false;
1521 	err = 1;
1522 
1523 unlock:
1524 	mutex_unlock(&chip->mutex);
1525 	return err;
1526 }
1527 
1528 /* get the current rate set to the given clock by any endpoint */
1529 int snd_usb_endpoint_get_clock_rate(struct snd_usb_audio *chip, int clock)
1530 {
1531 	struct snd_usb_clock_ref *ref;
1532 	int rate = 0;
1533 
1534 	if (!clock)
1535 		return 0;
1536 	mutex_lock(&chip->mutex);
1537 	list_for_each_entry(ref, &chip->clock_ref_list, list) {
1538 		if (ref->clock == clock) {
1539 			rate = ref->rate;
1540 			break;
1541 		}
1542 	}
1543 	mutex_unlock(&chip->mutex);
1544 	return rate;
1545 }
1546 
1547 /**
1548  * snd_usb_endpoint_start: start an snd_usb_endpoint
1549  *
1550  * @ep: the endpoint to start
1551  *
1552  * A call to this function will increment the running count of the endpoint.
1553  * In case it is not already running, the URBs for this endpoint will be
1554  * submitted. Otherwise, this function does nothing.
1555  *
1556  * Must be balanced to calls of snd_usb_endpoint_stop().
1557  *
1558  * Returns an error if the URB submission failed, 0 in all other cases.
1559  */
1560 int snd_usb_endpoint_start(struct snd_usb_endpoint *ep)
1561 {
1562 	bool is_playback = usb_pipeout(ep->pipe);
1563 	int err;
1564 	unsigned int i;
1565 
1566 	if (atomic_read(&ep->chip->shutdown))
1567 		return -EBADFD;
1568 
1569 	if (ep->sync_source)
1570 		WRITE_ONCE(ep->sync_source->sync_sink, ep);
1571 
1572 	usb_audio_dbg(ep->chip, "Starting %s EP 0x%x (running %d)\n",
1573 		      ep_type_name(ep->type), ep->ep_num,
1574 		      atomic_read(&ep->running));
1575 
1576 	/* already running? */
1577 	if (atomic_inc_return(&ep->running) != 1)
1578 		return 0;
1579 
1580 	if (ep->clock_ref)
1581 		atomic_inc(&ep->clock_ref->locked);
1582 
1583 	ep->active_mask = 0;
1584 	ep->unlink_mask = 0;
1585 	ep->phase = 0;
1586 	ep->sample_accum = 0;
1587 
1588 	snd_usb_endpoint_start_quirk(ep);
1589 
1590 	/*
1591 	 * If this endpoint has a data endpoint as implicit feedback source,
1592 	 * don't start the urbs here. Instead, mark them all as available,
1593 	 * wait for the record urbs to return and queue the playback urbs
1594 	 * from that context.
1595 	 */
1596 
1597 	if (!ep_state_update(ep, EP_STATE_STOPPED, EP_STATE_RUNNING))
1598 		goto __error;
1599 
1600 	if (snd_usb_endpoint_implicit_feedback_sink(ep) &&
1601 	    !(ep->chip->quirk_flags & QUIRK_FLAG_PLAYBACK_FIRST)) {
1602 		usb_audio_dbg(ep->chip, "No URB submission due to implicit fb sync\n");
1603 		i = 0;
1604 		goto fill_rest;
1605 	}
1606 
1607 	for (i = 0; i < ep->nurbs; i++) {
1608 		struct urb *urb = ep->urb[i].urb;
1609 
1610 		if (snd_BUG_ON(!urb))
1611 			goto __error;
1612 
1613 		if (is_playback)
1614 			err = prepare_outbound_urb(ep, urb->context, true);
1615 		else
1616 			err = prepare_inbound_urb(ep, urb->context);
1617 		if (err < 0) {
1618 			/* stop filling at applptr */
1619 			if (err == -EAGAIN)
1620 				break;
1621 			usb_audio_dbg(ep->chip,
1622 				      "EP 0x%x: failed to prepare urb: %d\n",
1623 				      ep->ep_num, err);
1624 			goto __error;
1625 		}
1626 
1627 		if (!atomic_read(&ep->chip->shutdown))
1628 			err = usb_submit_urb(urb, GFP_ATOMIC);
1629 		else
1630 			err = -ENODEV;
1631 		if (err < 0) {
1632 			if (!atomic_read(&ep->chip->shutdown))
1633 				usb_audio_err(ep->chip,
1634 					      "cannot submit urb %d, error %d: %s\n",
1635 					      i, err, usb_error_string(err));
1636 			goto __error;
1637 		}
1638 		set_bit(i, &ep->active_mask);
1639 		atomic_inc(&ep->submitted_urbs);
1640 	}
1641 
1642 	if (!i) {
1643 		usb_audio_dbg(ep->chip, "XRUN at starting EP 0x%x\n",
1644 			      ep->ep_num);
1645 		goto __error;
1646 	}
1647 
1648 	usb_audio_dbg(ep->chip, "%d URBs submitted for EP 0x%x\n",
1649 		      i, ep->ep_num);
1650 
1651  fill_rest:
1652 	/* put the remaining URBs to ready list */
1653 	if (is_playback) {
1654 		for (; i < ep->nurbs; i++)
1655 			push_back_to_ready_list(ep, ep->urb + i);
1656 	}
1657 
1658 	return 0;
1659 
1660 __error:
1661 	snd_usb_endpoint_stop(ep, false);
1662 	return -EPIPE;
1663 }
1664 
1665 /**
1666  * snd_usb_endpoint_stop: stop an snd_usb_endpoint
1667  *
1668  * @ep: the endpoint to stop (may be NULL)
1669  * @keep_pending: keep in-flight URBs
1670  *
1671  * A call to this function will decrement the running count of the endpoint.
1672  * In case the last user has requested the endpoint stop, the URBs will
1673  * actually be deactivated.
1674  *
1675  * Must be balanced to calls of snd_usb_endpoint_start().
1676  *
1677  * The caller needs to synchronize the pending stop operation via
1678  * snd_usb_endpoint_sync_pending_stop().
1679  */
1680 void snd_usb_endpoint_stop(struct snd_usb_endpoint *ep, bool keep_pending)
1681 {
1682 	if (!ep)
1683 		return;
1684 
1685 	usb_audio_dbg(ep->chip, "Stopping %s EP 0x%x (running %d)\n",
1686 		      ep_type_name(ep->type), ep->ep_num,
1687 		      atomic_read(&ep->running));
1688 
1689 	if (snd_BUG_ON(!atomic_read(&ep->running)))
1690 		return;
1691 
1692 	if (!atomic_dec_return(&ep->running)) {
1693 		if (ep->sync_source)
1694 			WRITE_ONCE(ep->sync_source->sync_sink, NULL);
1695 		stop_urbs(ep, false, keep_pending);
1696 		if (ep->clock_ref)
1697 			atomic_dec(&ep->clock_ref->locked);
1698 
1699 		if (ep->chip->quirk_flags & QUIRK_FLAG_FORCE_IFACE_RESET &&
1700 		    usb_pipeout(ep->pipe)) {
1701 			ep->need_prepare = true;
1702 			if (ep->iface_ref)
1703 				ep->iface_ref->need_setup = true;
1704 		}
1705 	}
1706 }
1707 
1708 /**
1709  * snd_usb_endpoint_release: Tear down an snd_usb_endpoint
1710  *
1711  * @ep: the endpoint to release
1712  *
1713  * This function does not care for the endpoint's running count but will tear
1714  * down all the streaming URBs immediately.
1715  */
1716 void snd_usb_endpoint_release(struct snd_usb_endpoint *ep)
1717 {
1718 	release_urbs(ep, true);
1719 }
1720 
1721 /**
1722  * snd_usb_endpoint_free_all: Free the resources of an snd_usb_endpoint
1723  * @chip: The chip
1724  *
1725  * This free all endpoints and those resources
1726  */
1727 void snd_usb_endpoint_free_all(struct snd_usb_audio *chip)
1728 {
1729 	struct snd_usb_endpoint *ep, *en;
1730 	struct snd_usb_iface_ref *ip, *in;
1731 	struct snd_usb_clock_ref *cp, *cn;
1732 
1733 	list_for_each_entry_safe(ep, en, &chip->ep_list, list)
1734 		kfree(ep);
1735 
1736 	list_for_each_entry_safe(ip, in, &chip->iface_ref_list, list)
1737 		kfree(ip);
1738 
1739 	list_for_each_entry_safe(cp, cn, &chip->clock_ref_list, list)
1740 		kfree(cp);
1741 }
1742 
1743 /*
1744  * snd_usb_handle_sync_urb: parse an USB sync packet
1745  *
1746  * @ep: the endpoint to handle the packet
1747  * @sender: the sending endpoint
1748  * @urb: the received packet
1749  *
1750  * This function is called from the context of an endpoint that received
1751  * the packet and is used to let another endpoint object handle the payload.
1752  */
1753 static void snd_usb_handle_sync_urb(struct snd_usb_endpoint *ep,
1754 				    struct snd_usb_endpoint *sender,
1755 				    const struct urb *urb)
1756 {
1757 	int shift;
1758 	unsigned int f;
1759 	unsigned long flags;
1760 
1761 	snd_BUG_ON(ep == sender);
1762 
1763 	/*
1764 	 * In case the endpoint is operating in implicit feedback mode, prepare
1765 	 * a new outbound URB that has the same layout as the received packet
1766 	 * and add it to the list of pending urbs. queue_pending_output_urbs()
1767 	 * will take care of them later.
1768 	 */
1769 	if (snd_usb_endpoint_implicit_feedback_sink(ep) &&
1770 	    atomic_read(&ep->running)) {
1771 
1772 		/* implicit feedback case */
1773 		int i, bytes = 0;
1774 		struct snd_urb_ctx *in_ctx;
1775 		struct snd_usb_packet_info *out_packet;
1776 
1777 		in_ctx = urb->context;
1778 
1779 		/* Count overall packet size */
1780 		for (i = 0; i < in_ctx->packets; i++)
1781 			if (urb->iso_frame_desc[i].status == 0)
1782 				bytes += urb->iso_frame_desc[i].actual_length;
1783 
1784 		/*
1785 		 * skip empty packets. At least M-Audio's Fast Track Ultra stops
1786 		 * streaming once it received a 0-byte OUT URB
1787 		 */
1788 		if (bytes == 0)
1789 			return;
1790 
1791 		spin_lock_irqsave(&ep->lock, flags);
1792 		if (ep->next_packet_queued >= ARRAY_SIZE(ep->next_packet)) {
1793 			spin_unlock_irqrestore(&ep->lock, flags);
1794 			usb_audio_err(ep->chip,
1795 				      "next package FIFO overflow EP 0x%x\n",
1796 				      ep->ep_num);
1797 			notify_xrun(ep);
1798 			return;
1799 		}
1800 
1801 		out_packet = next_packet_fifo_enqueue(ep);
1802 
1803 		/*
1804 		 * Iterate through the inbound packet and prepare the lengths
1805 		 * for the output packet. The OUT packet we are about to send
1806 		 * will have the same amount of payload bytes per stride as the
1807 		 * IN packet we just received. Since the actual size is scaled
1808 		 * by the stride, use the sender stride to calculate the length
1809 		 * in case the number of channels differ between the implicitly
1810 		 * fed-back endpoint and the synchronizing endpoint.
1811 		 */
1812 
1813 		out_packet->packets = in_ctx->packets;
1814 		for (i = 0; i < in_ctx->packets; i++) {
1815 			if (urb->iso_frame_desc[i].status == 0)
1816 				out_packet->packet_size[i] =
1817 					urb->iso_frame_desc[i].actual_length / sender->stride;
1818 			else
1819 				out_packet->packet_size[i] = 0;
1820 		}
1821 
1822 		spin_unlock_irqrestore(&ep->lock, flags);
1823 		snd_usb_queue_pending_output_urbs(ep, false);
1824 
1825 		return;
1826 	}
1827 
1828 	/*
1829 	 * process after playback sync complete
1830 	 *
1831 	 * Full speed devices report feedback values in 10.14 format as samples
1832 	 * per frame, high speed devices in 16.16 format as samples per
1833 	 * microframe.
1834 	 *
1835 	 * Because the Audio Class 1 spec was written before USB 2.0, many high
1836 	 * speed devices use a wrong interpretation, some others use an
1837 	 * entirely different format.
1838 	 *
1839 	 * Therefore, we cannot predict what format any particular device uses
1840 	 * and must detect it automatically.
1841 	 */
1842 
1843 	if (urb->iso_frame_desc[0].status != 0 ||
1844 	    urb->iso_frame_desc[0].actual_length < 3)
1845 		return;
1846 
1847 	f = le32_to_cpup(urb->transfer_buffer);
1848 	if (urb->iso_frame_desc[0].actual_length == 3)
1849 		f &= 0x00ffffff;
1850 	else
1851 		f &= 0x0fffffff;
1852 
1853 	if (f == 0)
1854 		return;
1855 
1856 	if (unlikely(sender->tenor_fb_quirk)) {
1857 		/*
1858 		 * Devices based on Tenor 8802 chipsets (TEAC UD-H01
1859 		 * and others) sometimes change the feedback value
1860 		 * by +/- 0x1.0000.
1861 		 */
1862 		if (f < ep->freqn - 0x8000)
1863 			f += 0xf000;
1864 		else if (f > ep->freqn + 0x8000)
1865 			f -= 0xf000;
1866 	} else if (unlikely(ep->freqshift == INT_MIN)) {
1867 		/*
1868 		 * The first time we see a feedback value, determine its format
1869 		 * by shifting it left or right until it matches the nominal
1870 		 * frequency value.  This assumes that the feedback does not
1871 		 * differ from the nominal value more than +50% or -25%.
1872 		 */
1873 		shift = 0;
1874 		while (f < ep->freqn - ep->freqn / 4) {
1875 			f <<= 1;
1876 			shift++;
1877 		}
1878 		while (f > ep->freqn + ep->freqn / 2) {
1879 			f >>= 1;
1880 			shift--;
1881 		}
1882 		ep->freqshift = shift;
1883 	} else if (ep->freqshift >= 0)
1884 		f <<= ep->freqshift;
1885 	else
1886 		f >>= -ep->freqshift;
1887 
1888 	if (likely(f >= ep->freqn - ep->freqn / 8 && f <= ep->freqmax)) {
1889 		/*
1890 		 * If the frequency looks valid, set it.
1891 		 * This value is referred to in prepare_playback_urb().
1892 		 */
1893 		spin_lock_irqsave(&ep->lock, flags);
1894 		ep->freqm = f;
1895 		spin_unlock_irqrestore(&ep->lock, flags);
1896 	} else {
1897 		/*
1898 		 * Out of range; maybe the shift value is wrong.
1899 		 * Reset it so that we autodetect again the next time.
1900 		 */
1901 		ep->freqshift = INT_MIN;
1902 	}
1903 }
1904 
1905