1 /*
2  * oxfw_stream.c - a part of driver for OXFW970/971 based devices
3  *
4  * Copyright (c) 2014 Takashi Sakamoto
5  *
6  * Licensed under the terms of the GNU General Public License, version 2.
7  */
8 
9 #include "oxfw.h"
10 #include <linux/delay.h>
11 
12 #define AVC_GENERIC_FRAME_MAXIMUM_BYTES	512
13 #define CALLBACK_TIMEOUT	200
14 
15 /*
16  * According to datasheet of Oxford Semiconductor:
17  *  OXFW970: 32.0/44.1/48.0/96.0 Khz, 8 audio channels I/O
18  *  OXFW971: 32.0/44.1/48.0/88.2/96.0/192.0 kHz, 16 audio channels I/O, MIDI I/O
19  */
20 static const unsigned int oxfw_rate_table[] = {
21 	[0] = 32000,
22 	[1] = 44100,
23 	[2] = 48000,
24 	[3] = 88200,
25 	[4] = 96000,
26 	[5] = 192000,
27 };
28 
29 /*
30  * See Table 5.7 – Sampling frequency for Multi-bit Audio
31  * in AV/C Stream Format Information Specification 1.1 (Apr 2005, 1394TA)
32  */
33 static const unsigned int avc_stream_rate_table[] = {
34 	[0] = 0x02,
35 	[1] = 0x03,
36 	[2] = 0x04,
37 	[3] = 0x0a,
38 	[4] = 0x05,
39 	[5] = 0x07,
40 };
41 
42 static int set_rate(struct snd_oxfw *oxfw, unsigned int rate)
43 {
44 	int err;
45 
46 	err = avc_general_set_sig_fmt(oxfw->unit, rate,
47 				      AVC_GENERAL_PLUG_DIR_IN, 0);
48 	if (err < 0)
49 		goto end;
50 
51 	if (oxfw->has_output)
52 		err = avc_general_set_sig_fmt(oxfw->unit, rate,
53 					      AVC_GENERAL_PLUG_DIR_OUT, 0);
54 end:
55 	return err;
56 }
57 
58 static int set_stream_format(struct snd_oxfw *oxfw, struct amdtp_stream *s,
59 			     unsigned int rate, unsigned int pcm_channels)
60 {
61 	u8 **formats;
62 	struct snd_oxfw_stream_formation formation;
63 	enum avc_general_plug_dir dir;
64 	unsigned int len;
65 	int i, err;
66 
67 	if (s == &oxfw->tx_stream) {
68 		formats = oxfw->tx_stream_formats;
69 		dir = AVC_GENERAL_PLUG_DIR_OUT;
70 	} else {
71 		formats = oxfw->rx_stream_formats;
72 		dir = AVC_GENERAL_PLUG_DIR_IN;
73 	}
74 
75 	/* Seek stream format for requirements. */
76 	for (i = 0; i < SND_OXFW_STREAM_FORMAT_ENTRIES; i++) {
77 		err = snd_oxfw_stream_parse_format(formats[i], &formation);
78 		if (err < 0)
79 			return err;
80 
81 		if ((formation.rate == rate) && (formation.pcm == pcm_channels))
82 			break;
83 	}
84 	if (i == SND_OXFW_STREAM_FORMAT_ENTRIES)
85 		return -EINVAL;
86 
87 	/* If assumed, just change rate. */
88 	if (oxfw->assumed)
89 		return set_rate(oxfw, rate);
90 
91 	/* Calculate format length. */
92 	len = 5 + formats[i][4] * 2;
93 
94 	err = avc_stream_set_format(oxfw->unit, dir, 0, formats[i], len);
95 	if (err < 0)
96 		return err;
97 
98 	/* Some requests just after changing format causes freezing. */
99 	msleep(100);
100 
101 	return 0;
102 }
103 
104 static void stop_stream(struct snd_oxfw *oxfw, struct amdtp_stream *stream)
105 {
106 	amdtp_stream_pcm_abort(stream);
107 	amdtp_stream_stop(stream);
108 
109 	if (stream == &oxfw->tx_stream)
110 		cmp_connection_break(&oxfw->out_conn);
111 	else
112 		cmp_connection_break(&oxfw->in_conn);
113 }
114 
115 static int start_stream(struct snd_oxfw *oxfw, struct amdtp_stream *stream)
116 {
117 	u8 **formats;
118 	enum avc_general_plug_dir dir;
119 	struct cmp_connection *conn;
120 	struct snd_oxfw_stream_formation formation;
121 	int i;
122 	int err;
123 
124 	if (stream == &oxfw->rx_stream) {
125 		dir = AVC_GENERAL_PLUG_DIR_IN;
126 		formats = oxfw->rx_stream_formats;
127 		conn = &oxfw->in_conn;
128 	} else {
129 		dir = AVC_GENERAL_PLUG_DIR_OUT;
130 		formats = oxfw->tx_stream_formats;
131 		conn = &oxfw->out_conn;
132 	}
133 
134 	err = snd_oxfw_stream_get_current_formation(oxfw, dir, &formation);
135 	if (err < 0)
136 		return err;
137 
138 	for (i = 0; i < SND_OXFW_STREAM_FORMAT_ENTRIES; i++) {
139 		struct snd_oxfw_stream_formation fmt;
140 
141 		if (formats[i] == NULL)
142 			break;
143 
144 		err = snd_oxfw_stream_parse_format(formats[i], &fmt);
145 		if (err < 0)
146 			return err;
147 		if (fmt.rate == formation.rate && fmt.pcm == formation.pcm &&
148 		    fmt.midi == formation.midi)
149 			break;
150 	}
151 	if (i == SND_OXFW_STREAM_FORMAT_ENTRIES)
152 		return -EINVAL;
153 
154 	// The stream should have one pcm channels at least.
155 	if (formation.pcm == 0)
156 		return -EINVAL;
157 
158 	err = amdtp_am824_set_parameters(stream, formation.rate, formation.pcm,
159 					 formation.midi * 8, false);
160 	if (err < 0)
161 		goto end;
162 
163 	err = cmp_connection_establish(conn,
164 				       amdtp_stream_get_max_payload(stream));
165 	if (err < 0)
166 		goto end;
167 
168 	err = amdtp_stream_start(stream,
169 				 conn->resources.channel,
170 				 conn->speed);
171 	if (err < 0) {
172 		cmp_connection_break(conn);
173 		goto end;
174 	}
175 
176 	/* Wait first packet */
177 	if (!amdtp_stream_wait_callback(stream, CALLBACK_TIMEOUT)) {
178 		stop_stream(oxfw, stream);
179 		err = -ETIMEDOUT;
180 	}
181 end:
182 	return err;
183 }
184 
185 static int check_connection_used_by_others(struct snd_oxfw *oxfw,
186 					   struct amdtp_stream *stream)
187 {
188 	struct cmp_connection *conn;
189 	bool used;
190 	int err;
191 
192 	if (stream == &oxfw->tx_stream)
193 		conn = &oxfw->out_conn;
194 	else
195 		conn = &oxfw->in_conn;
196 
197 	err = cmp_connection_check_used(conn, &used);
198 	if ((err >= 0) && used && !amdtp_stream_running(stream)) {
199 		dev_err(&oxfw->unit->device,
200 			"Connection established by others: %cPCR[%d]\n",
201 			(conn->direction == CMP_OUTPUT) ? 'o' : 'i',
202 			conn->pcr_index);
203 		err = -EBUSY;
204 	}
205 
206 	return err;
207 }
208 
209 int snd_oxfw_stream_init_simplex(struct snd_oxfw *oxfw,
210 				 struct amdtp_stream *stream)
211 {
212 	struct cmp_connection *conn;
213 	enum cmp_direction c_dir;
214 	enum amdtp_stream_direction s_dir;
215 	int err;
216 
217 	if (stream == &oxfw->tx_stream) {
218 		conn = &oxfw->out_conn;
219 		c_dir = CMP_OUTPUT;
220 		s_dir = AMDTP_IN_STREAM;
221 	} else {
222 		conn = &oxfw->in_conn;
223 		c_dir = CMP_INPUT;
224 		s_dir = AMDTP_OUT_STREAM;
225 	}
226 
227 	err = cmp_connection_init(conn, oxfw->unit, c_dir, 0);
228 	if (err < 0)
229 		goto end;
230 
231 	err = amdtp_am824_init(stream, oxfw->unit, s_dir, CIP_NONBLOCKING);
232 	if (err < 0) {
233 		amdtp_stream_destroy(stream);
234 		cmp_connection_destroy(conn);
235 		goto end;
236 	}
237 
238 	/*
239 	 * OXFW starts to transmit packets with non-zero dbc.
240 	 * OXFW postpone transferring packets till handling any asynchronous
241 	 * packets. As a result, next isochronous packet includes more data
242 	 * blocks than IEC 61883-6 defines.
243 	 */
244 	if (stream == &oxfw->tx_stream) {
245 		oxfw->tx_stream.flags |= CIP_JUMBO_PAYLOAD;
246 		if (oxfw->wrong_dbs)
247 			oxfw->tx_stream.flags |= CIP_WRONG_DBS;
248 	}
249 end:
250 	return err;
251 }
252 
253 int snd_oxfw_stream_start_simplex(struct snd_oxfw *oxfw,
254 				  struct amdtp_stream *stream,
255 				  unsigned int rate, unsigned int pcm_channels)
256 {
257 	struct snd_oxfw_stream_formation formation;
258 	enum avc_general_plug_dir dir;
259 	int err = 0;
260 
261 	if (oxfw->capture_substreams == 0 && oxfw->playback_substreams == 0)
262 		return -EIO;
263 
264 	// Considering JACK/FFADO streaming:
265 	// TODO: This can be removed hwdep functionality becomes popular.
266 	err = check_connection_used_by_others(oxfw, &oxfw->rx_stream);
267 	if (err < 0)
268 		return err;
269 	if (oxfw->has_output) {
270 		err = check_connection_used_by_others(oxfw, &oxfw->tx_stream);
271 		if (err < 0)
272 			return err;
273 	}
274 
275 	if (stream == &oxfw->tx_stream)
276 		dir = AVC_GENERAL_PLUG_DIR_OUT;
277 	else
278 		dir = AVC_GENERAL_PLUG_DIR_IN;
279 
280 	err = snd_oxfw_stream_get_current_formation(oxfw, dir, &formation);
281 	if (err < 0)
282 		return err;
283 	if (rate == 0)
284 		rate = formation.rate;
285 	if (pcm_channels == 0)
286 		pcm_channels = formation.pcm;
287 
288 	if (formation.rate != rate || formation.pcm != pcm_channels ||
289 	    amdtp_streaming_error(&oxfw->rx_stream) ||
290 	    amdtp_streaming_error(&oxfw->tx_stream)) {
291 		stop_stream(oxfw, &oxfw->rx_stream);
292 		if (oxfw->has_output)
293 			stop_stream(oxfw, &oxfw->tx_stream);
294 
295 		err = set_stream_format(oxfw, stream, rate, pcm_channels);
296 		if (err < 0) {
297 			dev_err(&oxfw->unit->device,
298 				"fail to set stream format: %d\n", err);
299 			return err;
300 		}
301 	}
302 
303 	if (!amdtp_stream_running(&oxfw->rx_stream)) {
304 		err = start_stream(oxfw, &oxfw->rx_stream);
305 		if (err < 0) {
306 			dev_err(&oxfw->unit->device,
307 				"fail to start rx stream: %d\n", err);
308 			goto error;
309 		}
310 	}
311 
312 	if (oxfw->has_output) {
313 		if (!amdtp_stream_running(&oxfw->tx_stream)) {
314 			err = start_stream(oxfw, &oxfw->tx_stream);
315 			if (err < 0) {
316 				dev_err(&oxfw->unit->device,
317 					"fail to start tx stream: %d\n", err);
318 				goto error;
319 			}
320 		}
321 	}
322 
323 	return 0;
324 error:
325 	stop_stream(oxfw, &oxfw->rx_stream);
326 	cmp_connection_break(&oxfw->in_conn);
327 	if (oxfw->has_output) {
328 		stop_stream(oxfw, &oxfw->tx_stream);
329 		cmp_connection_break(&oxfw->out_conn);
330 	}
331 	return err;
332 }
333 
334 void snd_oxfw_stream_stop_simplex(struct snd_oxfw *oxfw,
335 				  struct amdtp_stream *stream)
336 {
337 	if (oxfw->capture_substreams == 0 && oxfw->playback_substreams == 0) {
338 		stop_stream(oxfw, &oxfw->rx_stream);
339 
340 		if (oxfw->has_output)
341 			stop_stream(oxfw, &oxfw->tx_stream);
342 	}
343 }
344 
345 /*
346  * This function should be called before starting the stream or after stopping
347  * the streams.
348  */
349 void snd_oxfw_stream_destroy_simplex(struct snd_oxfw *oxfw,
350 				     struct amdtp_stream *stream)
351 {
352 	struct cmp_connection *conn;
353 
354 	if (stream == &oxfw->tx_stream)
355 		conn = &oxfw->out_conn;
356 	else
357 		conn = &oxfw->in_conn;
358 
359 	amdtp_stream_destroy(stream);
360 	cmp_connection_destroy(conn);
361 }
362 
363 void snd_oxfw_stream_update_simplex(struct snd_oxfw *oxfw,
364 				    struct amdtp_stream *stream)
365 {
366 	stop_stream(oxfw, &oxfw->rx_stream);
367 
368 	if (oxfw->has_output)
369 		stop_stream(oxfw, &oxfw->tx_stream);
370 }
371 
372 int snd_oxfw_stream_get_current_formation(struct snd_oxfw *oxfw,
373 				enum avc_general_plug_dir dir,
374 				struct snd_oxfw_stream_formation *formation)
375 {
376 	u8 *format;
377 	unsigned int len;
378 	int err;
379 
380 	len = AVC_GENERIC_FRAME_MAXIMUM_BYTES;
381 	format = kmalloc(len, GFP_KERNEL);
382 	if (format == NULL)
383 		return -ENOMEM;
384 
385 	err = avc_stream_get_format_single(oxfw->unit, dir, 0, format, &len);
386 	if (err < 0)
387 		goto end;
388 	if (len < 3) {
389 		err = -EIO;
390 		goto end;
391 	}
392 
393 	err = snd_oxfw_stream_parse_format(format, formation);
394 end:
395 	kfree(format);
396 	return err;
397 }
398 
399 /*
400  * See Table 6.16 - AM824 Stream Format
401  *     Figure 6.19 - format_information field for AM824 Compound
402  * in AV/C Stream Format Information Specification 1.1 (Apr 2005, 1394TA)
403  * Also 'Clause 12 AM824 sequence adaption layers' in IEC 61883-6:2005
404  */
405 int snd_oxfw_stream_parse_format(u8 *format,
406 				 struct snd_oxfw_stream_formation *formation)
407 {
408 	unsigned int i, e, channels, type;
409 
410 	memset(formation, 0, sizeof(struct snd_oxfw_stream_formation));
411 
412 	/*
413 	 * this module can support a hierarchy combination that:
414 	 *  Root:	Audio and Music (0x90)
415 	 *  Level 1:	AM824 Compound  (0x40)
416 	 */
417 	if ((format[0] != 0x90) || (format[1] != 0x40))
418 		return -ENOSYS;
419 
420 	/* check the sampling rate */
421 	for (i = 0; i < ARRAY_SIZE(avc_stream_rate_table); i++) {
422 		if (format[2] == avc_stream_rate_table[i])
423 			break;
424 	}
425 	if (i == ARRAY_SIZE(avc_stream_rate_table))
426 		return -ENOSYS;
427 
428 	formation->rate = oxfw_rate_table[i];
429 
430 	for (e = 0; e < format[4]; e++) {
431 		channels = format[5 + e * 2];
432 		type = format[6 + e * 2];
433 
434 		switch (type) {
435 		/* IEC 60958 Conformant, currently handled as MBLA */
436 		case 0x00:
437 		/* Multi Bit Linear Audio (Raw) */
438 		case 0x06:
439 			formation->pcm += channels;
440 			break;
441 		/* MIDI Conformant */
442 		case 0x0d:
443 			formation->midi = channels;
444 			break;
445 		/* IEC 61937-3 to 7 */
446 		case 0x01:
447 		case 0x02:
448 		case 0x03:
449 		case 0x04:
450 		case 0x05:
451 		/* Multi Bit Linear Audio */
452 		case 0x07:	/* DVD-Audio */
453 		case 0x0c:	/* High Precision */
454 		/* One Bit Audio */
455 		case 0x08:	/* (Plain) Raw */
456 		case 0x09:	/* (Plain) SACD */
457 		case 0x0a:	/* (Encoded) Raw */
458 		case 0x0b:	/* (Encoded) SACD */
459 		/* SMPTE Time-Code conformant */
460 		case 0x0e:
461 		/* Sample Count */
462 		case 0x0f:
463 		/* Anciliary Data */
464 		case 0x10:
465 		/* Synchronization Stream (Stereo Raw audio) */
466 		case 0x40:
467 		/* Don't care */
468 		case 0xff:
469 		default:
470 			return -ENOSYS;	/* not supported */
471 		}
472 	}
473 
474 	if (formation->pcm  > AM824_MAX_CHANNELS_FOR_PCM ||
475 	    formation->midi > AM824_MAX_CHANNELS_FOR_MIDI)
476 		return -ENOSYS;
477 
478 	return 0;
479 }
480 
481 static int
482 assume_stream_formats(struct snd_oxfw *oxfw, enum avc_general_plug_dir dir,
483 		      unsigned int pid, u8 *buf, unsigned int *len,
484 		      u8 **formats)
485 {
486 	struct snd_oxfw_stream_formation formation;
487 	unsigned int i, eid;
488 	int err;
489 
490 	/* get format at current sampling rate */
491 	err = avc_stream_get_format_single(oxfw->unit, dir, pid, buf, len);
492 	if (err < 0) {
493 		dev_err(&oxfw->unit->device,
494 		"fail to get current stream format for isoc %s plug %d:%d\n",
495 			(dir == AVC_GENERAL_PLUG_DIR_IN) ? "in" : "out",
496 			pid, err);
497 		goto end;
498 	}
499 
500 	/* parse and set stream format */
501 	eid = 0;
502 	err = snd_oxfw_stream_parse_format(buf, &formation);
503 	if (err < 0)
504 		goto end;
505 
506 	formats[eid] = devm_kmemdup(&oxfw->card->card_dev, buf, *len,
507 				    GFP_KERNEL);
508 	if (!formats[eid]) {
509 		err = -ENOMEM;
510 		goto end;
511 	}
512 
513 	/* apply the format for each available sampling rate */
514 	for (i = 0; i < ARRAY_SIZE(oxfw_rate_table); i++) {
515 		if (formation.rate == oxfw_rate_table[i])
516 			continue;
517 
518 		err = avc_general_inquiry_sig_fmt(oxfw->unit,
519 						  oxfw_rate_table[i],
520 						  dir, pid);
521 		if (err < 0)
522 			continue;
523 
524 		eid++;
525 		formats[eid] = devm_kmemdup(&oxfw->card->card_dev, buf, *len,
526 					    GFP_KERNEL);
527 		if (formats[eid] == NULL) {
528 			err = -ENOMEM;
529 			goto end;
530 		}
531 		formats[eid][2] = avc_stream_rate_table[i];
532 	}
533 
534 	err = 0;
535 	oxfw->assumed = true;
536 end:
537 	return err;
538 }
539 
540 static int fill_stream_formats(struct snd_oxfw *oxfw,
541 			       enum avc_general_plug_dir dir,
542 			       unsigned short pid)
543 {
544 	u8 *buf, **formats;
545 	unsigned int len, eid = 0;
546 	struct snd_oxfw_stream_formation dummy;
547 	int err;
548 
549 	buf = kmalloc(AVC_GENERIC_FRAME_MAXIMUM_BYTES, GFP_KERNEL);
550 	if (buf == NULL)
551 		return -ENOMEM;
552 
553 	if (dir == AVC_GENERAL_PLUG_DIR_OUT)
554 		formats = oxfw->tx_stream_formats;
555 	else
556 		formats = oxfw->rx_stream_formats;
557 
558 	/* get first entry */
559 	len = AVC_GENERIC_FRAME_MAXIMUM_BYTES;
560 	err = avc_stream_get_format_list(oxfw->unit, dir, 0, buf, &len, 0);
561 	if (err == -ENOSYS) {
562 		/* LIST subfunction is not implemented */
563 		len = AVC_GENERIC_FRAME_MAXIMUM_BYTES;
564 		err = assume_stream_formats(oxfw, dir, pid, buf, &len,
565 					    formats);
566 		goto end;
567 	} else if (err < 0) {
568 		dev_err(&oxfw->unit->device,
569 			"fail to get stream format %d for isoc %s plug %d:%d\n",
570 			eid, (dir == AVC_GENERAL_PLUG_DIR_IN) ? "in" : "out",
571 			pid, err);
572 		goto end;
573 	}
574 
575 	/* LIST subfunction is implemented */
576 	while (eid < SND_OXFW_STREAM_FORMAT_ENTRIES) {
577 		/* The format is too short. */
578 		if (len < 3) {
579 			err = -EIO;
580 			break;
581 		}
582 
583 		/* parse and set stream format */
584 		err = snd_oxfw_stream_parse_format(buf, &dummy);
585 		if (err < 0)
586 			break;
587 
588 		formats[eid] = devm_kmemdup(&oxfw->card->card_dev, buf, len,
589 					    GFP_KERNEL);
590 		if (!formats[eid]) {
591 			err = -ENOMEM;
592 			break;
593 		}
594 
595 		/* get next entry */
596 		len = AVC_GENERIC_FRAME_MAXIMUM_BYTES;
597 		err = avc_stream_get_format_list(oxfw->unit, dir, 0,
598 						 buf, &len, ++eid);
599 		/* No entries remained. */
600 		if (err == -EINVAL) {
601 			err = 0;
602 			break;
603 		} else if (err < 0) {
604 			dev_err(&oxfw->unit->device,
605 			"fail to get stream format %d for isoc %s plug %d:%d\n",
606 				eid, (dir == AVC_GENERAL_PLUG_DIR_IN) ? "in" :
607 									"out",
608 				pid, err);
609 			break;
610 		}
611 	}
612 end:
613 	kfree(buf);
614 	return err;
615 }
616 
617 int snd_oxfw_stream_discover(struct snd_oxfw *oxfw)
618 {
619 	u8 plugs[AVC_PLUG_INFO_BUF_BYTES];
620 	struct snd_oxfw_stream_formation formation;
621 	u8 *format;
622 	unsigned int i;
623 	int err;
624 
625 	/* the number of plugs for isoc in/out, ext in/out  */
626 	err = avc_general_get_plug_info(oxfw->unit, 0x1f, 0x07, 0x00, plugs);
627 	if (err < 0) {
628 		dev_err(&oxfw->unit->device,
629 		"fail to get info for isoc/external in/out plugs: %d\n",
630 			err);
631 		goto end;
632 	} else if ((plugs[0] == 0) && (plugs[1] == 0)) {
633 		err = -ENOSYS;
634 		goto end;
635 	}
636 
637 	/* use oPCR[0] if exists */
638 	if (plugs[1] > 0) {
639 		err = fill_stream_formats(oxfw, AVC_GENERAL_PLUG_DIR_OUT, 0);
640 		if (err < 0)
641 			goto end;
642 
643 		for (i = 0; i < SND_OXFW_STREAM_FORMAT_ENTRIES; i++) {
644 			format = oxfw->tx_stream_formats[i];
645 			if (format == NULL)
646 				continue;
647 			err = snd_oxfw_stream_parse_format(format, &formation);
648 			if (err < 0)
649 				continue;
650 
651 			/* Add one MIDI port. */
652 			if (formation.midi > 0)
653 				oxfw->midi_input_ports = 1;
654 		}
655 
656 		oxfw->has_output = true;
657 	}
658 
659 	/* use iPCR[0] if exists */
660 	if (plugs[0] > 0) {
661 		err = fill_stream_formats(oxfw, AVC_GENERAL_PLUG_DIR_IN, 0);
662 		if (err < 0)
663 			goto end;
664 
665 		for (i = 0; i < SND_OXFW_STREAM_FORMAT_ENTRIES; i++) {
666 			format = oxfw->rx_stream_formats[i];
667 			if (format == NULL)
668 				continue;
669 			err = snd_oxfw_stream_parse_format(format, &formation);
670 			if (err < 0)
671 				continue;
672 
673 			/* Add one MIDI port. */
674 			if (formation.midi > 0)
675 				oxfw->midi_output_ports = 1;
676 		}
677 	}
678 end:
679 	return err;
680 }
681 
682 void snd_oxfw_stream_lock_changed(struct snd_oxfw *oxfw)
683 {
684 	oxfw->dev_lock_changed = true;
685 	wake_up(&oxfw->hwdep_wait);
686 }
687 
688 int snd_oxfw_stream_lock_try(struct snd_oxfw *oxfw)
689 {
690 	int err;
691 
692 	spin_lock_irq(&oxfw->lock);
693 
694 	/* user land lock this */
695 	if (oxfw->dev_lock_count < 0) {
696 		err = -EBUSY;
697 		goto end;
698 	}
699 
700 	/* this is the first time */
701 	if (oxfw->dev_lock_count++ == 0)
702 		snd_oxfw_stream_lock_changed(oxfw);
703 	err = 0;
704 end:
705 	spin_unlock_irq(&oxfw->lock);
706 	return err;
707 }
708 
709 void snd_oxfw_stream_lock_release(struct snd_oxfw *oxfw)
710 {
711 	spin_lock_irq(&oxfw->lock);
712 
713 	if (WARN_ON(oxfw->dev_lock_count <= 0))
714 		goto end;
715 	if (--oxfw->dev_lock_count == 0)
716 		snd_oxfw_stream_lock_changed(oxfw);
717 end:
718 	spin_unlock_irq(&oxfw->lock);
719 }
720