xref: /linux/sound/usb/endpoint.c (revision c36461825469a9ceee2346a2e89286c522525da7)
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 synced_next_packet_size(struct snd_usb_endpoint *ep,
164 				   unsigned int avail)
165 {
166 	unsigned int phase;
167 	int ret;
168 
169 	if (ep->fill_max)
170 		return ep->maxframesize;
171 
172 	guard(spinlock_irqsave)(&ep->lock);
173 	phase = (ep->phase & 0xffff) + (ep->freqm << ep->datainterval);
174 	ret = min(phase >> 16, ep->maxframesize);
175 	if (avail && ret >= avail)
176 		ret = -EAGAIN;
177 	else
178 		ep->phase = phase;
179 	return ret;
180 }
181 
182 /*
183  * Return the number of samples to be sent in the next packet
184  * for adaptive and synchronous endpoints
185  */
186 static int next_packet_size(struct snd_usb_endpoint *ep, unsigned int avail)
187 {
188 	unsigned int sample_accum;
189 	int ret;
190 
191 	if (ep->fill_max)
192 		return ep->maxframesize;
193 
194 	sample_accum = ep->sample_accum + ep->sample_rem;
195 	if (sample_accum >= ep->pps) {
196 		sample_accum -= ep->pps;
197 		ret = ep->packsize[1];
198 	} else {
199 		ret = ep->packsize[0];
200 	}
201 	if (avail && ret >= avail)
202 		ret = -EAGAIN;
203 	else
204 		ep->sample_accum = sample_accum;
205 
206 	return ret;
207 }
208 
209 /*
210  * snd_usb_endpoint_next_packet_size: Return the number of samples to be sent
211  * in the next packet
212  *
213  * If the size is equal or exceeds @avail, don't proceed but return -EAGAIN
214  * Exception: @avail = 0 for skipping the check.
215  */
216 int snd_usb_endpoint_next_packet_size(struct snd_usb_endpoint *ep,
217 				      struct snd_urb_ctx *ctx, int idx,
218 				      unsigned int avail)
219 {
220 	unsigned int packet;
221 
222 	packet = ctx->packet_size[idx];
223 	if (packet) {
224 		packet = min(packet, ep->maxframesize);
225 		if (avail && packet >= avail)
226 			return -EAGAIN;
227 		return packet;
228 	}
229 
230 	if (ep->sync_source)
231 		return synced_next_packet_size(ep, avail);
232 	else
233 		return next_packet_size(ep, avail);
234 }
235 
236 static void call_retire_callback(struct snd_usb_endpoint *ep,
237 				 struct urb *urb)
238 {
239 	struct snd_usb_substream *data_subs;
240 
241 	data_subs = READ_ONCE(ep->data_subs);
242 	if (data_subs && ep->retire_data_urb)
243 		ep->retire_data_urb(data_subs, urb);
244 }
245 
246 static void retire_outbound_urb(struct snd_usb_endpoint *ep,
247 				struct snd_urb_ctx *urb_ctx)
248 {
249 	call_retire_callback(ep, urb_ctx->urb);
250 }
251 
252 static void snd_usb_handle_sync_urb(struct snd_usb_endpoint *ep,
253 				    struct snd_usb_endpoint *sender,
254 				    const struct urb *urb);
255 
256 static void retire_inbound_urb(struct snd_usb_endpoint *ep,
257 			       struct snd_urb_ctx *urb_ctx)
258 {
259 	struct urb *urb = urb_ctx->urb;
260 	struct snd_usb_endpoint *sync_sink;
261 
262 	if (unlikely(ep->skip_packets > 0)) {
263 		ep->skip_packets--;
264 		return;
265 	}
266 
267 	sync_sink = READ_ONCE(ep->sync_sink);
268 	if (sync_sink)
269 		snd_usb_handle_sync_urb(sync_sink, ep, urb);
270 
271 	call_retire_callback(ep, urb);
272 }
273 
274 static inline bool has_tx_length_quirk(struct snd_usb_audio *chip)
275 {
276 	return chip->quirk_flags & QUIRK_FLAG_TX_LENGTH;
277 }
278 
279 static int prepare_silent_urb(struct snd_usb_endpoint *ep,
280 			      struct snd_urb_ctx *ctx)
281 {
282 	struct urb *urb = ctx->urb;
283 	unsigned int offs = 0;
284 	unsigned int extra = 0;
285 	__le32 packet_length;
286 	int i;
287 
288 	/* For tx_length_quirk, put packet length at start of packet */
289 	if (has_tx_length_quirk(ep->chip))
290 		extra = sizeof(packet_length);
291 
292 	for (i = 0; i < ctx->packets; ++i) {
293 		int length;
294 
295 		length = snd_usb_endpoint_next_packet_size(ep, ctx, i, 0);
296 		if (length < 0)
297 			return length;
298 		length *= ep->stride; /* number of silent bytes */
299 		if (offs + length + extra > ctx->buffer_size)
300 			break;
301 		urb->iso_frame_desc[i].offset = offs;
302 		urb->iso_frame_desc[i].length = length + extra;
303 		if (extra) {
304 			packet_length = cpu_to_le32(length);
305 			memcpy(urb->transfer_buffer + offs,
306 			       &packet_length, sizeof(packet_length));
307 			offs += extra;
308 		}
309 		memset(urb->transfer_buffer + offs,
310 		       ep->silence_value, length);
311 		offs += length;
312 	}
313 
314 	if (!offs)
315 		return -EPIPE;
316 
317 	urb->number_of_packets = i;
318 	urb->transfer_buffer_length = offs;
319 	ctx->queued = 0;
320 	return 0;
321 }
322 
323 /*
324  * Prepare a PLAYBACK urb for submission to the bus.
325  */
326 static int prepare_outbound_urb(struct snd_usb_endpoint *ep,
327 				struct snd_urb_ctx *ctx,
328 				bool in_stream_lock)
329 {
330 	struct urb *urb = ctx->urb;
331 	unsigned char *cp = urb->transfer_buffer;
332 	struct snd_usb_substream *data_subs;
333 
334 	urb->dev = ep->chip->dev; /* we need to set this at each time */
335 
336 	switch (ep->type) {
337 	case SND_USB_ENDPOINT_TYPE_DATA:
338 		data_subs = READ_ONCE(ep->data_subs);
339 		if (data_subs && ep->prepare_data_urb)
340 			return ep->prepare_data_urb(data_subs, urb, in_stream_lock);
341 		/* no data provider, so send silence */
342 		return prepare_silent_urb(ep, ctx);
343 
344 	case SND_USB_ENDPOINT_TYPE_SYNC:
345 		if (snd_usb_get_speed(ep->chip->dev) >= USB_SPEED_HIGH) {
346 			/*
347 			 * fill the length and offset of each urb descriptor.
348 			 * the fixed 12.13 frequency is passed as 16.16 through the pipe.
349 			 */
350 			urb->iso_frame_desc[0].length = 4;
351 			urb->iso_frame_desc[0].offset = 0;
352 			cp[0] = ep->freqn;
353 			cp[1] = ep->freqn >> 8;
354 			cp[2] = ep->freqn >> 16;
355 			cp[3] = ep->freqn >> 24;
356 		} else {
357 			/*
358 			 * fill the length and offset of each urb descriptor.
359 			 * the fixed 10.14 frequency is passed through the pipe.
360 			 */
361 			urb->iso_frame_desc[0].length = 3;
362 			urb->iso_frame_desc[0].offset = 0;
363 			cp[0] = ep->freqn >> 2;
364 			cp[1] = ep->freqn >> 10;
365 			cp[2] = ep->freqn >> 18;
366 		}
367 
368 		break;
369 	}
370 	return 0;
371 }
372 
373 /*
374  * Prepare a CAPTURE or SYNC urb for submission to the bus.
375  */
376 static int prepare_inbound_urb(struct snd_usb_endpoint *ep,
377 			       struct snd_urb_ctx *urb_ctx)
378 {
379 	int i, offs;
380 	struct urb *urb = urb_ctx->urb;
381 
382 	urb->dev = ep->chip->dev; /* we need to set this at each time */
383 
384 	switch (ep->type) {
385 	case SND_USB_ENDPOINT_TYPE_DATA:
386 		offs = 0;
387 		for (i = 0; i < urb_ctx->packets; i++) {
388 			if (offs + ep->curpacksize > urb_ctx->buffer_size)
389 				break;
390 			urb->iso_frame_desc[i].offset = offs;
391 			urb->iso_frame_desc[i].length = ep->curpacksize;
392 			offs += ep->curpacksize;
393 		}
394 
395 		urb->transfer_buffer_length = offs;
396 		urb->number_of_packets = i;
397 		break;
398 
399 	case SND_USB_ENDPOINT_TYPE_SYNC:
400 		urb->iso_frame_desc[0].length = min(4u, ep->syncmaxsize);
401 		urb->iso_frame_desc[0].offset = 0;
402 		break;
403 	}
404 	return 0;
405 }
406 
407 /* notify an error as XRUN to the assigned PCM data substream */
408 static bool notify_xrun(struct snd_usb_endpoint *ep)
409 {
410 	struct snd_usb_substream *data_subs;
411 	struct snd_pcm_substream *psubs;
412 
413 	data_subs = READ_ONCE(ep->data_subs);
414 	if (!data_subs)
415 		return false;
416 	psubs = data_subs->pcm_substream;
417 	if (psubs && psubs->runtime &&
418 	    psubs->runtime->state == SNDRV_PCM_STATE_RUNNING) {
419 		snd_pcm_stop_xrun(psubs);
420 		return true;
421 	}
422 	return false;
423 }
424 
425 static struct snd_usb_packet_info *
426 next_packet_fifo_enqueue(struct snd_usb_endpoint *ep)
427 {
428 	struct snd_usb_packet_info *p;
429 
430 	p = ep->next_packet + (ep->next_packet_head + ep->next_packet_queued) %
431 		ARRAY_SIZE(ep->next_packet);
432 	ep->next_packet_queued++;
433 	return p;
434 }
435 
436 static struct snd_usb_packet_info *
437 next_packet_fifo_dequeue(struct snd_usb_endpoint *ep)
438 {
439 	struct snd_usb_packet_info *p;
440 
441 	p = ep->next_packet + ep->next_packet_head;
442 	ep->next_packet_head++;
443 	ep->next_packet_head %= ARRAY_SIZE(ep->next_packet);
444 	ep->next_packet_queued--;
445 	return p;
446 }
447 
448 static void push_back_to_ready_list(struct snd_usb_endpoint *ep,
449 				    struct snd_urb_ctx *ctx)
450 {
451 	guard(spinlock_irqsave)(&ep->lock);
452 	list_add_tail(&ctx->ready_list, &ep->ready_playback_urbs);
453 }
454 
455 /*
456  * Send output urbs that have been prepared previously. URBs are dequeued
457  * from ep->ready_playback_urbs and in case there aren't any available
458  * or there are no packets that have been prepared, this function does
459  * nothing.
460  *
461  * The reason why the functionality of sending and preparing URBs is separated
462  * is that host controllers don't guarantee the order in which they return
463  * inbound and outbound packets to their submitters.
464  *
465  * This function is used both for implicit feedback endpoints and in low-
466  * latency playback mode.
467  */
468 int snd_usb_queue_pending_output_urbs(struct snd_usb_endpoint *ep,
469 				      bool in_stream_lock)
470 {
471 	bool implicit_fb = snd_usb_endpoint_implicit_feedback_sink(ep);
472 
473 	while (ep_state_running(ep)) {
474 		struct snd_usb_packet_info *packet;
475 		struct snd_urb_ctx *ctx = NULL;
476 		int err;
477 
478 		scoped_guard(spinlock_irqsave, &ep->lock) {
479 			if ((!implicit_fb || ep->next_packet_queued > 0) &&
480 			    !list_empty(&ep->ready_playback_urbs)) {
481 				/* take URB out of FIFO */
482 				ctx = list_first_entry(&ep->ready_playback_urbs,
483 						       struct snd_urb_ctx, ready_list);
484 				list_del_init(&ctx->ready_list);
485 				if (implicit_fb)
486 					packet = next_packet_fifo_dequeue(ep);
487 			}
488 		}
489 
490 		if (ctx == NULL)
491 			break;
492 
493 		/* copy over the length information */
494 		if (implicit_fb) {
495 			ctx->packets = packet->packets;
496 			memcpy(ctx->packet_size, packet->packet_size,
497 			       packet->packets * sizeof(packet->packet_size[0]));
498 		}
499 
500 		/* call the data handler to fill in playback data */
501 		err = prepare_outbound_urb(ep, ctx, in_stream_lock);
502 		/* can be stopped during prepare callback */
503 		if (unlikely(!ep_state_running(ep)))
504 			break;
505 		if (err < 0) {
506 			/* push back to ready list again for -EAGAIN */
507 			if (err == -EAGAIN) {
508 				push_back_to_ready_list(ep, ctx);
509 				break;
510 			}
511 
512 			if (!in_stream_lock)
513 				notify_xrun(ep);
514 			return -EPIPE;
515 		}
516 
517 		if (!atomic_read(&ep->chip->shutdown))
518 			err = usb_submit_urb(ctx->urb, GFP_ATOMIC);
519 		else
520 			err = -ENODEV;
521 		if (err < 0) {
522 			if (!atomic_read(&ep->chip->shutdown)) {
523 				usb_audio_err(ep->chip,
524 					      "Unable to submit urb #%d: %d at %s\n",
525 					      ctx->index, err, __func__);
526 				if (!in_stream_lock)
527 					notify_xrun(ep);
528 			}
529 			return -EPIPE;
530 		}
531 
532 		set_bit(ctx->index, &ep->active_mask);
533 		atomic_inc(&ep->submitted_urbs);
534 	}
535 
536 	return 0;
537 }
538 
539 /*
540  * complete callback for urbs
541  */
542 static void snd_complete_urb(struct urb *urb)
543 {
544 	struct snd_urb_ctx *ctx = urb->context;
545 	struct snd_usb_endpoint *ep = ctx->ep;
546 	int err;
547 
548 	if (unlikely(urb->status == -ENOENT ||		/* unlinked */
549 		     urb->status == -ENODEV ||		/* device removed */
550 		     urb->status == -ECONNRESET ||	/* unlinked */
551 		     urb->status == -ESHUTDOWN))	/* device disabled */
552 		goto exit_clear;
553 	/* device disconnected */
554 	if (unlikely(atomic_read(&ep->chip->shutdown)))
555 		goto exit_clear;
556 
557 	if (unlikely(!ep_state_running(ep)))
558 		goto exit_clear;
559 
560 	if (usb_pipeout(ep->pipe)) {
561 		retire_outbound_urb(ep, ctx);
562 		/* can be stopped during retire callback */
563 		if (unlikely(!ep_state_running(ep)))
564 			goto exit_clear;
565 
566 		/* in low-latency and implicit-feedback modes, push back the
567 		 * URB to ready list at first, then process as much as possible
568 		 */
569 		if (ep->lowlatency_playback ||
570 		     snd_usb_endpoint_implicit_feedback_sink(ep)) {
571 			push_back_to_ready_list(ep, ctx);
572 			clear_bit(ctx->index, &ep->active_mask);
573 			snd_usb_queue_pending_output_urbs(ep, false);
574 			/* decrement at last, and check xrun */
575 			if (atomic_dec_and_test(&ep->submitted_urbs) &&
576 			    !snd_usb_endpoint_implicit_feedback_sink(ep))
577 				notify_xrun(ep);
578 			return;
579 		}
580 
581 		/* in non-lowlatency mode, no error handling for prepare */
582 		prepare_outbound_urb(ep, ctx, false);
583 		/* can be stopped during prepare callback */
584 		if (unlikely(!ep_state_running(ep)))
585 			goto exit_clear;
586 	} else {
587 		retire_inbound_urb(ep, ctx);
588 		/* can be stopped during retire callback */
589 		if (unlikely(!ep_state_running(ep)))
590 			goto exit_clear;
591 
592 		prepare_inbound_urb(ep, ctx);
593 	}
594 
595 	if (!atomic_read(&ep->chip->shutdown))
596 		err = usb_submit_urb(urb, GFP_ATOMIC);
597 	else
598 		err = -ENODEV;
599 	if (err == 0)
600 		return;
601 
602 	if (!atomic_read(&ep->chip->shutdown)) {
603 		if (notify_xrun(ep))
604 			usb_audio_err(ep->chip,
605 				      "cannot submit urb (err = %d)\n", err);
606 	}
607 
608 exit_clear:
609 	clear_bit(ctx->index, &ep->active_mask);
610 	atomic_dec(&ep->submitted_urbs);
611 }
612 
613 /*
614  * Find or create a refcount object for the given interface
615  *
616  * The objects are released altogether in snd_usb_endpoint_free_all()
617  */
618 static struct snd_usb_iface_ref *
619 iface_ref_find(struct snd_usb_audio *chip, int iface)
620 {
621 	struct snd_usb_iface_ref *ip;
622 
623 	list_for_each_entry(ip, &chip->iface_ref_list, list)
624 		if (ip->iface == iface)
625 			return ip;
626 
627 	ip = kzalloc_obj(*ip);
628 	if (!ip)
629 		return NULL;
630 	ip->iface = iface;
631 	list_add_tail(&ip->list, &chip->iface_ref_list);
632 	return ip;
633 }
634 
635 /* Similarly, a refcount object for clock */
636 static struct snd_usb_clock_ref *
637 clock_ref_find(struct snd_usb_audio *chip, int clock)
638 {
639 	struct snd_usb_clock_ref *ref;
640 
641 	list_for_each_entry(ref, &chip->clock_ref_list, list)
642 		if (ref->clock == clock)
643 			return ref;
644 
645 	ref = kzalloc_obj(*ref);
646 	if (!ref)
647 		return NULL;
648 	ref->clock = clock;
649 	atomic_set(&ref->locked, 0);
650 	list_add_tail(&ref->list, &chip->clock_ref_list);
651 	return ref;
652 }
653 
654 /*
655  * Get the existing endpoint object corresponding EP
656  * Returns NULL if not present.
657  */
658 struct snd_usb_endpoint *
659 snd_usb_get_endpoint(struct snd_usb_audio *chip, int ep_num)
660 {
661 	struct snd_usb_endpoint *ep;
662 
663 	list_for_each_entry(ep, &chip->ep_list, list) {
664 		if (ep->ep_num == ep_num)
665 			return ep;
666 	}
667 
668 	return NULL;
669 }
670 
671 #define ep_type_name(type) \
672 	(type == SND_USB_ENDPOINT_TYPE_DATA ? "data" : "sync")
673 
674 /**
675  * snd_usb_add_endpoint: Add an endpoint to an USB audio chip
676  *
677  * @chip: The chip
678  * @ep_num: The number of the endpoint to use
679  * @type: SND_USB_ENDPOINT_TYPE_DATA or SND_USB_ENDPOINT_TYPE_SYNC
680  *
681  * If the requested endpoint has not been added to the given chip before,
682  * a new instance is created.
683  *
684  * Returns zero on success or a negative error code.
685  *
686  * New endpoints will be added to chip->ep_list and freed by
687  * calling snd_usb_endpoint_free_all().
688  *
689  * For SND_USB_ENDPOINT_TYPE_SYNC, the caller needs to guarantee that
690  * bNumEndpoints > 1 beforehand.
691  */
692 int snd_usb_add_endpoint(struct snd_usb_audio *chip, int ep_num, int type)
693 {
694 	struct snd_usb_endpoint *ep;
695 	bool is_playback;
696 
697 	ep = snd_usb_get_endpoint(chip, ep_num);
698 	if (ep)
699 		return 0;
700 
701 	usb_audio_dbg(chip, "Creating new %s endpoint #%x\n",
702 		      ep_type_name(type),
703 		      ep_num);
704 	ep = kzalloc_obj(*ep);
705 	if (!ep)
706 		return -ENOMEM;
707 
708 	ep->chip = chip;
709 	spin_lock_init(&ep->lock);
710 	ep->type = type;
711 	ep->ep_num = ep_num;
712 	INIT_LIST_HEAD(&ep->ready_playback_urbs);
713 	atomic_set(&ep->submitted_urbs, 0);
714 
715 	is_playback = ((ep_num & USB_ENDPOINT_DIR_MASK) == USB_DIR_OUT);
716 	ep_num &= USB_ENDPOINT_NUMBER_MASK;
717 	if (is_playback)
718 		ep->pipe = usb_sndisocpipe(chip->dev, ep_num);
719 	else
720 		ep->pipe = usb_rcvisocpipe(chip->dev, ep_num);
721 
722 	list_add_tail(&ep->list, &chip->ep_list);
723 	return 0;
724 }
725 
726 /* Set up syncinterval and maxsyncsize for a sync EP */
727 static void endpoint_set_syncinterval(struct snd_usb_audio *chip,
728 				      struct snd_usb_endpoint *ep)
729 {
730 	struct usb_host_interface *alts;
731 	struct usb_endpoint_descriptor *desc;
732 
733 	alts = snd_usb_get_host_interface(chip, ep->iface, ep->altsetting);
734 	if (!alts)
735 		return;
736 
737 	desc = get_endpoint(alts, ep->ep_idx);
738 	if (desc->bLength >= USB_DT_ENDPOINT_AUDIO_SIZE &&
739 	    desc->bRefresh >= 1 && desc->bRefresh <= 9)
740 		ep->syncinterval = desc->bRefresh;
741 	else if (snd_usb_get_speed(chip->dev) == USB_SPEED_FULL)
742 		ep->syncinterval = 1;
743 	else if (desc->bInterval >= 1 && desc->bInterval <= 16)
744 		ep->syncinterval = desc->bInterval - 1;
745 	else
746 		ep->syncinterval = 3;
747 
748 	ep->syncmaxsize = le16_to_cpu(desc->wMaxPacketSize);
749 }
750 
751 static bool endpoint_compatible(struct snd_usb_endpoint *ep,
752 				const struct audioformat *fp,
753 				const struct snd_pcm_hw_params *params)
754 {
755 	if (!ep->opened)
756 		return false;
757 	if (ep->cur_audiofmt != fp)
758 		return false;
759 	if (ep->cur_rate != params_rate(params) ||
760 	    ep->cur_format != params_format(params) ||
761 	    ep->cur_period_frames != params_period_size(params) ||
762 	    ep->cur_buffer_periods != params_periods(params))
763 		return false;
764 	return true;
765 }
766 
767 /*
768  * Check whether the given fp and hw params are compatible with the current
769  * setup of the target EP for implicit feedback sync
770  */
771 bool snd_usb_endpoint_compatible(struct snd_usb_audio *chip,
772 				 struct snd_usb_endpoint *ep,
773 				 const struct audioformat *fp,
774 				 const struct snd_pcm_hw_params *params)
775 {
776 	guard(mutex)(&chip->mutex);
777 	return endpoint_compatible(ep, fp, params);
778 }
779 
780 /*
781  * snd_usb_endpoint_open: Open the endpoint
782  *
783  * Called from hw_params to assign the endpoint to the substream.
784  * It's reference-counted, and only the first opener is allowed to set up
785  * arbitrary parameters.  The later opener must be compatible with the
786  * former opened parameters.
787  * The endpoint needs to be closed via snd_usb_endpoint_close() later.
788  *
789  * Note that this function doesn't configure the endpoint.  The substream
790  * needs to set it up later via snd_usb_endpoint_set_params() and
791  * snd_usb_endpoint_prepare().
792  */
793 struct snd_usb_endpoint *
794 snd_usb_endpoint_open(struct snd_usb_audio *chip,
795 		      const struct audioformat *fp,
796 		      const struct snd_pcm_hw_params *params,
797 		      bool is_sync_ep,
798 		      bool fixed_rate)
799 {
800 	struct snd_usb_endpoint *ep;
801 	int ep_num = is_sync_ep ? fp->sync_ep : fp->endpoint;
802 
803 	guard(mutex)(&chip->mutex);
804 	ep = snd_usb_get_endpoint(chip, ep_num);
805 	if (!ep) {
806 		usb_audio_err(chip, "Cannot find EP 0x%x to open\n", ep_num);
807 		return NULL;
808 	}
809 
810 	if (!ep->opened) {
811 		if (is_sync_ep) {
812 			ep->iface = fp->sync_iface;
813 			ep->altsetting = fp->sync_altsetting;
814 			ep->ep_idx = fp->sync_ep_idx;
815 		} else {
816 			ep->iface = fp->iface;
817 			ep->altsetting = fp->altsetting;
818 			ep->ep_idx = fp->ep_idx;
819 		}
820 		usb_audio_dbg(chip, "Open EP 0x%x, iface=%d:%d, idx=%d\n",
821 			      ep_num, ep->iface, ep->altsetting, ep->ep_idx);
822 
823 		ep->iface_ref = iface_ref_find(chip, ep->iface);
824 		if (!ep->iface_ref)
825 			return NULL;
826 
827 		if (fp->protocol != UAC_VERSION_1) {
828 			ep->clock_ref = clock_ref_find(chip, fp->clock);
829 			if (!ep->clock_ref)
830 				return NULL;
831 			ep->clock_ref->opened++;
832 		}
833 
834 		ep->cur_audiofmt = fp;
835 		ep->cur_channels = fp->channels;
836 		ep->cur_rate = params_rate(params);
837 		ep->cur_format = params_format(params);
838 		ep->cur_frame_bytes = snd_pcm_format_physical_width(ep->cur_format) *
839 			ep->cur_channels / 8;
840 		ep->cur_period_frames = params_period_size(params);
841 		ep->cur_period_bytes = ep->cur_period_frames * ep->cur_frame_bytes;
842 		ep->cur_buffer_periods = params_periods(params);
843 
844 		if (ep->type == SND_USB_ENDPOINT_TYPE_SYNC)
845 			endpoint_set_syncinterval(chip, ep);
846 
847 		ep->implicit_fb_sync = fp->implicit_fb;
848 		ep->need_setup = true;
849 		ep->need_prepare = true;
850 		ep->fixed_rate = fixed_rate;
851 
852 		usb_audio_dbg(chip, "  channels=%d, rate=%d, format=%s, period_bytes=%d, periods=%d, implicit_fb=%d\n",
853 			      ep->cur_channels, ep->cur_rate,
854 			      snd_pcm_format_name(ep->cur_format),
855 			      ep->cur_period_bytes, ep->cur_buffer_periods,
856 			      ep->implicit_fb_sync);
857 
858 	} else {
859 		if (WARN_ON(!ep->iface_ref))
860 			return NULL;
861 
862 		if (!endpoint_compatible(ep, fp, params)) {
863 			usb_audio_err(chip, "Incompatible EP setup for 0x%x\n",
864 				      ep_num);
865 			return NULL;
866 		}
867 
868 		usb_audio_dbg(chip, "Reopened EP 0x%x (count %d)\n",
869 			      ep_num, ep->opened);
870 	}
871 
872 	if (!ep->iface_ref->opened++)
873 		ep->iface_ref->need_setup = true;
874 
875 	ep->opened++;
876 	return ep;
877 }
878 
879 /*
880  * snd_usb_endpoint_set_sync: Link data and sync endpoints
881  *
882  * Pass NULL to sync_ep to unlink again
883  */
884 void snd_usb_endpoint_set_sync(struct snd_usb_audio *chip,
885 			       struct snd_usb_endpoint *data_ep,
886 			       struct snd_usb_endpoint *sync_ep)
887 {
888 	data_ep->sync_source = sync_ep;
889 }
890 
891 /*
892  * Set data endpoint callbacks and the assigned data stream
893  *
894  * Called at PCM trigger and cleanups.
895  * Pass NULL to deactivate each callback.
896  */
897 void snd_usb_endpoint_set_callback(struct snd_usb_endpoint *ep,
898 				   int (*prepare)(struct snd_usb_substream *subs,
899 						  struct urb *urb,
900 						  bool in_stream_lock),
901 				   void (*retire)(struct snd_usb_substream *subs,
902 						  struct urb *urb),
903 				   struct snd_usb_substream *data_subs)
904 {
905 	ep->prepare_data_urb = prepare;
906 	ep->retire_data_urb = retire;
907 	if (data_subs)
908 		ep->lowlatency_playback = data_subs->lowlatency_playback;
909 	else
910 		ep->lowlatency_playback = false;
911 	WRITE_ONCE(ep->data_subs, data_subs);
912 }
913 
914 static int endpoint_set_interface(struct snd_usb_audio *chip,
915 				  struct snd_usb_endpoint *ep,
916 				  bool set)
917 {
918 	int altset = set ? ep->altsetting : 0;
919 	int err;
920 	int retries = 0;
921 	const int max_retries = 5;
922 
923 	if (ep->iface_ref->altset == altset)
924 		return 0;
925 	/* already disconnected? */
926 	if (unlikely(atomic_read(&chip->shutdown)))
927 		return -ENODEV;
928 
929 	usb_audio_dbg(chip, "Setting usb interface %d:%d for EP 0x%x\n",
930 		      ep->iface, altset, ep->ep_num);
931 retry:
932 	err = usb_set_interface(chip->dev, ep->iface, altset);
933 	if (err < 0) {
934 		if (err == -EPROTO && ++retries <= max_retries) {
935 			msleep(5 * (1 << (retries - 1)));
936 			goto retry;
937 		}
938 		usb_audio_err_ratelimited(
939 			chip, "%d:%d: usb_set_interface failed (%d)\n",
940 			ep->iface, altset, err);
941 		return err;
942 	}
943 
944 	if (chip->quirk_flags & QUIRK_FLAG_IFACE_DELAY)
945 		msleep(50);
946 	ep->iface_ref->altset = altset;
947 	return 0;
948 }
949 
950 /*
951  * snd_usb_endpoint_close: Close the endpoint
952  *
953  * Unreference the already opened endpoint via snd_usb_endpoint_open().
954  */
955 void snd_usb_endpoint_close(struct snd_usb_audio *chip,
956 			    struct snd_usb_endpoint *ep)
957 {
958 	guard(mutex)(&chip->mutex);
959 	usb_audio_dbg(chip, "Closing EP 0x%x (count %d)\n",
960 		      ep->ep_num, ep->opened);
961 
962 	if (!--ep->iface_ref->opened &&
963 		!(chip->quirk_flags & QUIRK_FLAG_IFACE_SKIP_CLOSE))
964 		endpoint_set_interface(chip, ep, false);
965 
966 	if (!--ep->opened) {
967 		if (ep->clock_ref) {
968 			if (!--ep->clock_ref->opened)
969 				ep->clock_ref->rate = 0;
970 		}
971 		ep->iface = 0;
972 		ep->altsetting = 0;
973 		ep->cur_audiofmt = NULL;
974 		ep->cur_rate = 0;
975 		ep->iface_ref = NULL;
976 		ep->clock_ref = NULL;
977 		usb_audio_dbg(chip, "EP 0x%x closed\n", ep->ep_num);
978 	}
979 }
980 
981 /* Prepare for suspening EP, called from the main suspend handler */
982 void snd_usb_endpoint_suspend(struct snd_usb_endpoint *ep)
983 {
984 	ep->need_prepare = true;
985 	if (ep->iface_ref)
986 		ep->iface_ref->need_setup = true;
987 	if (ep->clock_ref)
988 		ep->clock_ref->rate = 0;
989 }
990 
991 /*
992  *  wait until all urbs are processed.
993  */
994 static int wait_clear_urbs(struct snd_usb_endpoint *ep)
995 {
996 	unsigned long end_time = jiffies + msecs_to_jiffies(1000);
997 	int alive;
998 
999 	if (atomic_read(&ep->state) != EP_STATE_STOPPING)
1000 		return 0;
1001 
1002 	do {
1003 		alive = atomic_read(&ep->submitted_urbs);
1004 		if (!alive)
1005 			break;
1006 
1007 		schedule_timeout_uninterruptible(1);
1008 	} while (time_before(jiffies, end_time));
1009 
1010 	if (alive)
1011 		usb_audio_err(ep->chip,
1012 			"timeout: still %d active urbs on EP #%x\n",
1013 			alive, ep->ep_num);
1014 
1015 	if (ep_state_update(ep, EP_STATE_STOPPING, EP_STATE_STOPPED)) {
1016 		ep->sync_sink = NULL;
1017 		snd_usb_endpoint_set_callback(ep, NULL, NULL, NULL);
1018 	}
1019 
1020 	return 0;
1021 }
1022 
1023 /* sync the pending stop operation;
1024  * this function itself doesn't trigger the stop operation
1025  */
1026 void snd_usb_endpoint_sync_pending_stop(struct snd_usb_endpoint *ep)
1027 {
1028 	if (ep)
1029 		wait_clear_urbs(ep);
1030 }
1031 
1032 /*
1033  * Stop active urbs
1034  *
1035  * This function moves the EP to STOPPING state if it's being RUNNING.
1036  */
1037 static int stop_urbs(struct snd_usb_endpoint *ep, bool force, bool keep_pending)
1038 {
1039 	unsigned int i;
1040 
1041 	if (!force && atomic_read(&ep->running))
1042 		return -EBUSY;
1043 
1044 	if (!ep_state_update(ep, EP_STATE_RUNNING, EP_STATE_STOPPING))
1045 		return 0;
1046 
1047 	scoped_guard(spinlock_irqsave, &ep->lock) {
1048 		INIT_LIST_HEAD(&ep->ready_playback_urbs);
1049 		ep->next_packet_head = 0;
1050 		ep->next_packet_queued = 0;
1051 	}
1052 
1053 	if (keep_pending)
1054 		return 0;
1055 
1056 	for (i = 0; i < ep->nurbs; i++) {
1057 		if (test_bit(i, &ep->active_mask)) {
1058 			if (!test_and_set_bit(i, &ep->unlink_mask)) {
1059 				struct urb *u = ep->urb[i].urb;
1060 				usb_unlink_urb(u);
1061 			}
1062 		}
1063 	}
1064 
1065 	return 0;
1066 }
1067 
1068 /*
1069  * release an endpoint's urbs
1070  */
1071 static int release_urbs(struct snd_usb_endpoint *ep, bool force)
1072 {
1073 	int i, err;
1074 
1075 	/* route incoming urbs to nirvana */
1076 	snd_usb_endpoint_set_callback(ep, NULL, NULL, NULL);
1077 
1078 	/* stop and unlink urbs */
1079 	err = stop_urbs(ep, force, false);
1080 	if (err)
1081 		return err;
1082 
1083 	wait_clear_urbs(ep);
1084 
1085 	for (i = 0; i < ep->nurbs; i++)
1086 		release_urb_ctx(&ep->urb[i]);
1087 
1088 	usb_free_coherent(ep->chip->dev, SYNC_URBS * 4,
1089 			  ep->syncbuf, ep->sync_dma);
1090 
1091 	ep->syncbuf = NULL;
1092 	ep->nurbs = 0;
1093 	return 0;
1094 }
1095 
1096 /*
1097  * configure a data endpoint
1098  */
1099 static int data_ep_set_params(struct snd_usb_endpoint *ep)
1100 {
1101 	struct snd_usb_audio *chip = ep->chip;
1102 	unsigned int maxsize, minsize, packs_per_ms, max_packs_per_urb;
1103 	unsigned int max_packs_per_period, urbs_per_period, urb_packs;
1104 	unsigned int max_urbs, i;
1105 	const struct audioformat *fmt = ep->cur_audiofmt;
1106 	int frame_bits = ep->cur_frame_bytes * 8;
1107 	int tx_length_quirk = (has_tx_length_quirk(chip) &&
1108 			       usb_pipeout(ep->pipe));
1109 
1110 	usb_audio_dbg(chip, "Setting params for data EP 0x%x, pipe 0x%x\n",
1111 		      ep->ep_num, ep->pipe);
1112 
1113 	if (ep->cur_format == SNDRV_PCM_FORMAT_DSD_U16_LE && fmt->dsd_dop) {
1114 		/*
1115 		 * When operating in DSD DOP mode, the size of a sample frame
1116 		 * in hardware differs from the actual physical format width
1117 		 * because we need to make room for the DOP markers.
1118 		 */
1119 		frame_bits += ep->cur_channels << 3;
1120 	}
1121 
1122 	ep->datainterval = fmt->datainterval;
1123 	ep->stride = frame_bits >> 3;
1124 
1125 	switch (ep->cur_format) {
1126 	case SNDRV_PCM_FORMAT_U8:
1127 		ep->silence_value = 0x80;
1128 		break;
1129 	case SNDRV_PCM_FORMAT_DSD_U8:
1130 	case SNDRV_PCM_FORMAT_DSD_U16_LE:
1131 	case SNDRV_PCM_FORMAT_DSD_U32_LE:
1132 	case SNDRV_PCM_FORMAT_DSD_U16_BE:
1133 	case SNDRV_PCM_FORMAT_DSD_U32_BE:
1134 		ep->silence_value = 0x69;
1135 		break;
1136 	default:
1137 		ep->silence_value = 0;
1138 	}
1139 
1140 	/* assume max. frequency is 50% higher than nominal */
1141 	ep->freqmax = ep->freqn + (ep->freqn >> 1);
1142 	/* Round up freqmax to nearest integer in order to calculate maximum
1143 	 * packet size, which must represent a whole number of frames.
1144 	 * This is accomplished by adding 0x0.ffff before converting the
1145 	 * Q16.16 format into integer.
1146 	 * In order to accurately calculate the maximum packet size when
1147 	 * the data interval is more than 1 (i.e. ep->datainterval > 0),
1148 	 * multiply by the data interval prior to rounding. For instance,
1149 	 * a freqmax of 41 kHz will result in a max packet size of 6 (5.125)
1150 	 * frames with a data interval of 1, but 11 (10.25) frames with a
1151 	 * data interval of 2.
1152 	 * (ep->freqmax << ep->datainterval overflows at 8.192 MHz for the
1153 	 * maximum datainterval value of 3, at USB full speed, higher for
1154 	 * USB high speed, noting that ep->freqmax is in units of
1155 	 * frames per packet in Q16.16 format.)
1156 	 */
1157 	maxsize = (((ep->freqmax << ep->datainterval) + 0xffff) >> 16) *
1158 			 (frame_bits >> 3);
1159 	if (tx_length_quirk)
1160 		maxsize += sizeof(__le32); /* Space for length descriptor */
1161 	/* but wMaxPacketSize might reduce this */
1162 	if (ep->maxpacksize && ep->maxpacksize < maxsize) {
1163 		/* whatever fits into a max. size packet */
1164 		unsigned int data_maxsize = maxsize = ep->maxpacksize;
1165 
1166 		if (tx_length_quirk)
1167 			/* Need to remove the length descriptor to calc freq */
1168 			data_maxsize -= sizeof(__le32);
1169 		ep->freqmax = (data_maxsize / (frame_bits >> 3))
1170 				<< (16 - ep->datainterval);
1171 	}
1172 
1173 	if (ep->fill_max) {
1174 		ep->curpacksize = ep->maxpacksize;
1175 		maxsize = ep->curpacksize;
1176 	} else {
1177 		ep->curpacksize = maxsize;
1178 	}
1179 
1180 	if (snd_usb_get_speed(chip->dev) != USB_SPEED_FULL) {
1181 		packs_per_ms = 8 >> ep->datainterval;
1182 		max_packs_per_urb = MAX_PACKS_HS;
1183 	} else {
1184 		packs_per_ms = 1;
1185 		max_packs_per_urb = MAX_PACKS;
1186 	}
1187 	if (ep->sync_source && !ep->implicit_fb_sync)
1188 		max_packs_per_urb = min(max_packs_per_urb,
1189 					1U << ep->sync_source->syncinterval);
1190 	max_packs_per_urb = max(1u, max_packs_per_urb >> ep->datainterval);
1191 
1192 	/*
1193 	 * Capture endpoints need to use small URBs because there's no way
1194 	 * to tell in advance where the next period will end, and we don't
1195 	 * want the next URB to complete much after the period ends.
1196 	 *
1197 	 * Playback endpoints with implicit sync much use the same parameters
1198 	 * as their corresponding capture endpoint.
1199 	 */
1200 	if (usb_pipein(ep->pipe) || ep->implicit_fb_sync) {
1201 
1202 		/* make capture URBs <= 1 ms and smaller than a period */
1203 		urb_packs = min(max_packs_per_urb, packs_per_ms);
1204 		while (urb_packs > 1 && urb_packs * maxsize >= ep->cur_period_bytes)
1205 			urb_packs >>= 1;
1206 		ep->nurbs = MAX_URBS;
1207 
1208 	/*
1209 	 * Playback endpoints without implicit sync are adjusted so that
1210 	 * a period fits as evenly as possible in the smallest number of
1211 	 * URBs.  The total number of URBs is adjusted to the size of the
1212 	 * ALSA buffer, subject to the MAX_URBS and MAX_QUEUE limits.
1213 	 */
1214 	} else {
1215 		/* determine how small a packet can be */
1216 		minsize = (ep->freqn >> (16 - ep->datainterval)) *
1217 				(frame_bits >> 3);
1218 		/* with sync from device, assume it can be 12% lower */
1219 		if (ep->sync_source)
1220 			minsize -= minsize >> 3;
1221 		minsize = max(minsize, 1u);
1222 
1223 		/* how many packets will contain an entire ALSA period? */
1224 		max_packs_per_period = DIV_ROUND_UP(ep->cur_period_bytes, minsize);
1225 
1226 		/* how many URBs will contain a period? */
1227 		urbs_per_period = DIV_ROUND_UP(max_packs_per_period,
1228 				max_packs_per_urb);
1229 		/* how many packets are needed in each URB? */
1230 		urb_packs = DIV_ROUND_UP(max_packs_per_period, urbs_per_period);
1231 
1232 		/* limit the number of frames in a single URB */
1233 		ep->max_urb_frames = DIV_ROUND_UP(ep->cur_period_frames,
1234 						  urbs_per_period);
1235 
1236 		/* try to use enough URBs to contain an entire ALSA buffer */
1237 		max_urbs = min((unsigned) MAX_URBS,
1238 				MAX_QUEUE * packs_per_ms / urb_packs);
1239 		ep->nurbs = min(max_urbs, urbs_per_period * ep->cur_buffer_periods);
1240 	}
1241 
1242 	/* allocate and initialize data urbs */
1243 	for (i = 0; i < ep->nurbs; i++) {
1244 		struct snd_urb_ctx *u = &ep->urb[i];
1245 		u->index = i;
1246 		u->ep = ep;
1247 		u->packets = urb_packs;
1248 
1249 		if (fmt->fmt_type == UAC_FORMAT_TYPE_II)
1250 			u->packets++; /* for transfer delimiter */
1251 		u->buffer_size = maxsize * u->packets;
1252 		u->urb = usb_alloc_urb(u->packets, GFP_KERNEL);
1253 		if (!u->urb)
1254 			goto out_of_memory;
1255 
1256 		u->urb->transfer_buffer =
1257 			usb_alloc_coherent(chip->dev, u->buffer_size,
1258 					   GFP_KERNEL, &u->urb->transfer_dma);
1259 		if (!u->urb->transfer_buffer)
1260 			goto out_of_memory;
1261 		u->urb->pipe = ep->pipe;
1262 		u->urb->transfer_flags = URB_NO_TRANSFER_DMA_MAP;
1263 		u->urb->interval = 1 << ep->datainterval;
1264 		u->urb->context = u;
1265 		u->urb->complete = snd_complete_urb;
1266 		INIT_LIST_HEAD(&u->ready_list);
1267 	}
1268 
1269 	return 0;
1270 
1271 out_of_memory:
1272 	release_urbs(ep, false);
1273 	return -ENOMEM;
1274 }
1275 
1276 /*
1277  * configure a sync endpoint
1278  */
1279 static int sync_ep_set_params(struct snd_usb_endpoint *ep)
1280 {
1281 	struct snd_usb_audio *chip = ep->chip;
1282 	int i;
1283 
1284 	usb_audio_dbg(chip, "Setting params for sync EP 0x%x, pipe 0x%x\n",
1285 		      ep->ep_num, ep->pipe);
1286 
1287 	ep->syncbuf = usb_alloc_coherent(chip->dev, SYNC_URBS * 4,
1288 					 GFP_KERNEL, &ep->sync_dma);
1289 	if (!ep->syncbuf)
1290 		return -ENOMEM;
1291 
1292 	ep->nurbs = SYNC_URBS;
1293 	for (i = 0; i < SYNC_URBS; i++) {
1294 		struct snd_urb_ctx *u = &ep->urb[i];
1295 		u->index = i;
1296 		u->ep = ep;
1297 		u->packets = 1;
1298 		u->urb = usb_alloc_urb(1, GFP_KERNEL);
1299 		if (!u->urb)
1300 			goto out_of_memory;
1301 		u->urb->transfer_buffer = ep->syncbuf + i * 4;
1302 		u->urb->transfer_dma = ep->sync_dma + i * 4;
1303 		u->urb->transfer_buffer_length = 4;
1304 		u->urb->pipe = ep->pipe;
1305 		u->urb->transfer_flags = URB_NO_TRANSFER_DMA_MAP;
1306 		u->urb->number_of_packets = 1;
1307 		u->urb->interval = 1 << ep->syncinterval;
1308 		u->urb->context = u;
1309 		u->urb->complete = snd_complete_urb;
1310 	}
1311 
1312 	return 0;
1313 
1314 out_of_memory:
1315 	release_urbs(ep, false);
1316 	return -ENOMEM;
1317 }
1318 
1319 /* update the rate of the referred clock; return the actual rate */
1320 static int update_clock_ref_rate(struct snd_usb_audio *chip,
1321 				 struct snd_usb_endpoint *ep)
1322 {
1323 	struct snd_usb_clock_ref *clock = ep->clock_ref;
1324 	int rate = ep->cur_rate;
1325 
1326 	if (!clock || clock->rate == rate)
1327 		return rate;
1328 	if (clock->rate) {
1329 		if (atomic_read(&clock->locked))
1330 			return clock->rate;
1331 		if (clock->rate != rate) {
1332 			usb_audio_err(chip, "Mismatched sample rate %d vs %d for EP 0x%x\n",
1333 				      clock->rate, rate, ep->ep_num);
1334 			return clock->rate;
1335 		}
1336 	}
1337 	clock->rate = rate;
1338 	clock->need_setup = true;
1339 	return rate;
1340 }
1341 
1342 /*
1343  * snd_usb_endpoint_set_params: configure an snd_usb_endpoint
1344  *
1345  * It's called either from hw_params callback.
1346  * Determine the number of URBs to be used on this endpoint.
1347  * An endpoint must be configured before it can be started.
1348  * An endpoint that is already running can not be reconfigured.
1349  */
1350 int snd_usb_endpoint_set_params(struct snd_usb_audio *chip,
1351 				struct snd_usb_endpoint *ep)
1352 {
1353 	const struct audioformat *fmt = ep->cur_audiofmt;
1354 	int err;
1355 
1356 	guard(mutex)(&chip->mutex);
1357 	if (!ep->need_setup)
1358 		return 0;
1359 
1360 	/* release old buffers, if any */
1361 	err = release_urbs(ep, false);
1362 	if (err < 0)
1363 		return err;
1364 
1365 	ep->datainterval = fmt->datainterval;
1366 	ep->maxpacksize = fmt->maxpacksize;
1367 	ep->fill_max = !!(fmt->attributes & UAC_EP_CS_ATTR_FILL_MAX);
1368 
1369 	if (snd_usb_get_speed(chip->dev) == USB_SPEED_FULL) {
1370 		ep->freqn = get_usb_full_speed_rate(ep->cur_rate);
1371 		ep->pps = 1000 >> ep->datainterval;
1372 	} else {
1373 		ep->freqn = get_usb_high_speed_rate(ep->cur_rate);
1374 		ep->pps = 8000 >> ep->datainterval;
1375 	}
1376 
1377 	ep->sample_rem = ep->cur_rate % ep->pps;
1378 	ep->packsize[0] = ep->cur_rate / ep->pps;
1379 	ep->packsize[1] = (ep->cur_rate + (ep->pps - 1)) / ep->pps;
1380 	if (ep->packsize[1] > ep->maxpacksize) {
1381 		usb_audio_dbg(chip, "Too small maxpacksize %u for rate %u / pps %u\n",
1382 			      ep->maxpacksize, ep->cur_rate, ep->pps);
1383 		return -EINVAL;
1384 	}
1385 
1386 	/* calculate the frequency in 16.16 format */
1387 	ep->freqm = ep->freqn;
1388 	ep->freqshift = INT_MIN;
1389 
1390 	ep->phase = 0;
1391 
1392 	switch (ep->type) {
1393 	case  SND_USB_ENDPOINT_TYPE_DATA:
1394 		err = data_ep_set_params(ep);
1395 		break;
1396 	case  SND_USB_ENDPOINT_TYPE_SYNC:
1397 		err = sync_ep_set_params(ep);
1398 		break;
1399 	default:
1400 		err = -EINVAL;
1401 	}
1402 
1403 	usb_audio_dbg(chip, "Set up %d URBS, ret=%d\n", ep->nurbs, err);
1404 
1405 	if (err < 0)
1406 		return err;
1407 
1408 	/* some unit conversions in runtime */
1409 	ep->maxframesize = ep->maxpacksize / ep->cur_frame_bytes;
1410 	ep->curframesize = ep->curpacksize / ep->cur_frame_bytes;
1411 
1412 	ep->packsize[0] = min(ep->packsize[0], ep->maxframesize);
1413 	ep->packsize[1] = min(ep->packsize[1], ep->maxframesize);
1414 
1415 	err = update_clock_ref_rate(chip, ep);
1416 	if (err >= 0) {
1417 		ep->need_setup = false;
1418 		err = 0;
1419 	}
1420 
1421 	return err;
1422 }
1423 
1424 static int init_sample_rate(struct snd_usb_audio *chip,
1425 			    struct snd_usb_endpoint *ep)
1426 {
1427 	struct snd_usb_clock_ref *clock = ep->clock_ref;
1428 	int rate, err;
1429 
1430 	rate = update_clock_ref_rate(chip, ep);
1431 	if (rate < 0)
1432 		return rate;
1433 	if (clock && !clock->need_setup)
1434 		return 0;
1435 
1436 	if (!ep->fixed_rate) {
1437 		err = snd_usb_init_sample_rate(chip, ep->cur_audiofmt, rate);
1438 		if (err < 0) {
1439 			if (clock)
1440 				clock->rate = 0; /* reset rate */
1441 			return err;
1442 		}
1443 	}
1444 
1445 	if (clock)
1446 		clock->need_setup = false;
1447 	return 0;
1448 }
1449 
1450 /*
1451  * snd_usb_endpoint_prepare: Prepare the endpoint
1452  *
1453  * This function sets up the EP to be fully usable state.
1454  * It's called either from prepare callback.
1455  * The function checks need_setup flag, and performs nothing unless needed,
1456  * so it's safe to call this multiple times.
1457  *
1458  * This returns zero if unchanged, 1 if the configuration has changed,
1459  * or a negative error code.
1460  */
1461 int snd_usb_endpoint_prepare(struct snd_usb_audio *chip,
1462 			     struct snd_usb_endpoint *ep)
1463 {
1464 	bool iface_first;
1465 	int err = 0;
1466 
1467 	guard(mutex)(&chip->mutex);
1468 	if (WARN_ON(!ep->iface_ref))
1469 		return 0;
1470 	if (!ep->need_prepare)
1471 		return 0;
1472 
1473 	/* If the interface has been already set up, just set EP parameters */
1474 	if (!ep->iface_ref->need_setup) {
1475 		/* sample rate setup of UAC1 is per endpoint, and we need
1476 		 * to update at each EP configuration
1477 		 */
1478 		if (ep->cur_audiofmt->protocol == UAC_VERSION_1) {
1479 			err = init_sample_rate(chip, ep);
1480 			if (err < 0)
1481 				return err;
1482 		}
1483 		goto done;
1484 	}
1485 
1486 	/* Need to deselect altsetting at first */
1487 	endpoint_set_interface(chip, ep, false);
1488 
1489 	/* Some UAC1 devices (e.g. Yamaha THR10) need the host interface
1490 	 * to be set up before parameter setups
1491 	 */
1492 	iface_first = ep->cur_audiofmt->protocol == UAC_VERSION_1;
1493 	/* Workaround for devices that require the interface setup at first like UAC1 */
1494 	if (chip->quirk_flags & QUIRK_FLAG_SET_IFACE_FIRST)
1495 		iface_first = true;
1496 	if (iface_first) {
1497 		err = endpoint_set_interface(chip, ep, true);
1498 		if (err < 0)
1499 			return err;
1500 	}
1501 
1502 	err = snd_usb_select_mode_quirk(chip, ep->cur_audiofmt);
1503 	if (err < 0)
1504 		return err;
1505 
1506 	err = snd_usb_init_pitch(chip, ep->cur_audiofmt);
1507 	if (err < 0)
1508 		return err;
1509 
1510 	err = init_sample_rate(chip, ep);
1511 	if (err < 0)
1512 		return err;
1513 
1514 	/* for UAC2/3, enable the interface altset here at last */
1515 	if (!iface_first) {
1516 		err = endpoint_set_interface(chip, ep, true);
1517 		if (err < 0)
1518 			return err;
1519 	}
1520 
1521 	ep->iface_ref->need_setup = false;
1522 
1523  done:
1524 	ep->need_prepare = false;
1525 	return 1;
1526 }
1527 EXPORT_SYMBOL_GPL(snd_usb_endpoint_prepare);
1528 
1529 /* get the current rate set to the given clock by any endpoint */
1530 int snd_usb_endpoint_get_clock_rate(struct snd_usb_audio *chip, int clock)
1531 {
1532 	struct snd_usb_clock_ref *ref;
1533 	int rate = 0;
1534 
1535 	if (!clock)
1536 		return 0;
1537 	guard(mutex)(&chip->mutex);
1538 	list_for_each_entry(ref, &chip->clock_ref_list, list) {
1539 		if (ref->clock == clock) {
1540 			rate = ref->rate;
1541 			break;
1542 		}
1543 	}
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 		 * However, on devices where bytes==0 means every sync-source
1789 		 * packet errored (e.g. Behringer Flow 8 returning -EXDEV bursts
1790 		 * for entire capture URBs), an unconditional return starves the
1791 		 * IFB-fed OUT ring permanently. Such devices set
1792 		 * QUIRK_FLAG_IFB_SILENCE_ON_EMPTY to fall through and enqueue a
1793 		 * packet_info with size 0 packets, so playback emits silence
1794 		 * and the OUT ring keeps moving.
1795 		 */
1796 		if (bytes == 0 && !(ep->chip->quirk_flags & QUIRK_FLAG_IFB_SILENCE_ON_EMPTY))
1797 			return;
1798 
1799 		spin_lock_irqsave(&ep->lock, flags);
1800 		if (ep->next_packet_queued >= ARRAY_SIZE(ep->next_packet)) {
1801 			spin_unlock_irqrestore(&ep->lock, flags);
1802 			if (notify_xrun(ep)) {
1803 				usb_audio_err(ep->chip,
1804 					      "next packet FIFO overflow EP 0x%x\n",
1805 					      ep->ep_num);
1806 			}
1807 			return;
1808 		}
1809 
1810 		out_packet = next_packet_fifo_enqueue(ep);
1811 
1812 		/*
1813 		 * Iterate through the inbound packet and prepare the lengths
1814 		 * for the output packet. The OUT packet we are about to send
1815 		 * will have the same amount of payload bytes per stride as the
1816 		 * IN packet we just received. Since the actual size is scaled
1817 		 * by the stride, use the sender stride to calculate the length
1818 		 * in case the number of channels differ between the implicitly
1819 		 * fed-back endpoint and the synchronizing endpoint.
1820 		 */
1821 
1822 		out_packet->packets = in_ctx->packets;
1823 		for (i = 0; i < in_ctx->packets; i++) {
1824 			if (urb->iso_frame_desc[i].status == 0) {
1825 				unsigned int frames =
1826 					urb->iso_frame_desc[i].actual_length / sender->stride;
1827 				out_packet->packet_size[i] = min(frames, ep->maxframesize);
1828 			} else {
1829 				out_packet->packet_size[i] = 0;
1830 			}
1831 		}
1832 
1833 		spin_unlock_irqrestore(&ep->lock, flags);
1834 		snd_usb_queue_pending_output_urbs(ep, false);
1835 
1836 		return;
1837 	}
1838 
1839 	/*
1840 	 * process after playback sync complete
1841 	 *
1842 	 * Full speed devices report feedback values in 10.14 format as samples
1843 	 * per frame, high speed devices in 16.16 format as samples per
1844 	 * microframe.
1845 	 *
1846 	 * Because the Audio Class 1 spec was written before USB 2.0, many high
1847 	 * speed devices use a wrong interpretation, some others use an
1848 	 * entirely different format.
1849 	 *
1850 	 * Therefore, we cannot predict what format any particular device uses
1851 	 * and must detect it automatically.
1852 	 */
1853 
1854 	if (urb->iso_frame_desc[0].status != 0 ||
1855 	    urb->iso_frame_desc[0].actual_length < 3)
1856 		return;
1857 
1858 	f = le32_to_cpup(urb->transfer_buffer);
1859 	if (urb->iso_frame_desc[0].actual_length == 3)
1860 		f &= 0x00ffffff;
1861 	else
1862 		f &= 0x0fffffff;
1863 
1864 	if (f == 0)
1865 		return;
1866 
1867 	if (unlikely(sender->tenor_fb_quirk)) {
1868 		/*
1869 		 * Devices based on Tenor 8802 chipsets (TEAC UD-H01
1870 		 * and others) sometimes change the feedback value
1871 		 * by +/- 0x1.0000.
1872 		 */
1873 		if (f < ep->freqn - 0x8000)
1874 			f += 0xf000;
1875 		else if (f > ep->freqn + 0x8000)
1876 			f -= 0xf000;
1877 	} else if (unlikely(ep->freqshift == INT_MIN)) {
1878 		/*
1879 		 * The first time we see a feedback value, determine its format
1880 		 * by shifting it left or right until it matches the nominal
1881 		 * frequency value.  This assumes that the feedback does not
1882 		 * differ from the nominal value more than +50% or -25%.
1883 		 */
1884 		shift = 0;
1885 		while (f < ep->freqn - ep->freqn / 4) {
1886 			f <<= 1;
1887 			shift++;
1888 		}
1889 		while (f > ep->freqn + ep->freqn / 2) {
1890 			f >>= 1;
1891 			shift--;
1892 		}
1893 		ep->freqshift = shift;
1894 	} else if (ep->freqshift >= 0)
1895 		f <<= ep->freqshift;
1896 	else
1897 		f >>= -ep->freqshift;
1898 
1899 	if (likely(f >= ep->freqn - ep->freqn / 8 && f <= ep->freqmax)) {
1900 		/*
1901 		 * If the frequency looks valid, set it.
1902 		 * This value is referred to in prepare_playback_urb().
1903 		 */
1904 		guard(spinlock_irqsave)(&ep->lock);
1905 		ep->freqm = f;
1906 	} else {
1907 		/*
1908 		 * Out of range; maybe the shift value is wrong.
1909 		 * Reset it so that we autodetect again the next time.
1910 		 */
1911 		ep->freqshift = INT_MIN;
1912 	}
1913 }
1914 
1915