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 			unsigned int rate, unsigned int pcm_channels)
117 {
118 	u8 **formats;
119 	struct cmp_connection *conn;
120 	struct snd_oxfw_stream_formation formation;
121 	unsigned int i, midi_ports;
122 	int err;
123 
124 	if (stream == &oxfw->rx_stream) {
125 		formats = oxfw->rx_stream_formats;
126 		conn = &oxfw->in_conn;
127 	} else {
128 		formats = oxfw->tx_stream_formats;
129 		conn = &oxfw->out_conn;
130 	}
131 
132 	/* Get stream format */
133 	for (i = 0; i < SND_OXFW_STREAM_FORMAT_ENTRIES; i++) {
134 		if (formats[i] == NULL)
135 			break;
136 
137 		err = snd_oxfw_stream_parse_format(formats[i], &formation);
138 		if (err < 0)
139 			goto end;
140 		if (rate != formation.rate)
141 			continue;
142 		if (pcm_channels == 0 ||  pcm_channels == formation.pcm)
143 			break;
144 	}
145 	if (i == SND_OXFW_STREAM_FORMAT_ENTRIES) {
146 		err = -EINVAL;
147 		goto end;
148 	}
149 
150 	pcm_channels = formation.pcm;
151 	midi_ports = formation.midi * 8;
152 
153 	/* The stream should have one pcm channels at least */
154 	if (pcm_channels == 0) {
155 		err = -EINVAL;
156 		goto end;
157 	}
158 	err = amdtp_am824_set_parameters(stream, rate, pcm_channels, midi_ports,
159 					 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_SKIP_INIT_DBC_CHECK |
246 					 CIP_JUMBO_PAYLOAD;
247 		if (oxfw->wrong_dbs)
248 			oxfw->tx_stream.flags |= CIP_WRONG_DBS;
249 	}
250 end:
251 	return err;
252 }
253 
254 int snd_oxfw_stream_start_simplex(struct snd_oxfw *oxfw,
255 				  struct amdtp_stream *stream,
256 				  unsigned int rate, unsigned int pcm_channels)
257 {
258 	struct amdtp_stream *opposite;
259 	struct snd_oxfw_stream_formation formation;
260 	enum avc_general_plug_dir dir;
261 	unsigned int substreams, opposite_substreams;
262 	int err = 0;
263 
264 	if (stream == &oxfw->tx_stream) {
265 		substreams = oxfw->capture_substreams;
266 		opposite = &oxfw->rx_stream;
267 		opposite_substreams = oxfw->playback_substreams;
268 		dir = AVC_GENERAL_PLUG_DIR_OUT;
269 	} else {
270 		substreams = oxfw->playback_substreams;
271 		opposite_substreams = oxfw->capture_substreams;
272 
273 		if (oxfw->has_output)
274 			opposite = &oxfw->rx_stream;
275 		else
276 			opposite = NULL;
277 
278 		dir = AVC_GENERAL_PLUG_DIR_IN;
279 	}
280 
281 	if (substreams == 0)
282 		goto end;
283 
284 	/*
285 	 * Considering JACK/FFADO streaming:
286 	 * TODO: This can be removed hwdep functionality becomes popular.
287 	 */
288 	err = check_connection_used_by_others(oxfw, stream);
289 	if (err < 0)
290 		goto end;
291 
292 	/* packet queueing error */
293 	if (amdtp_streaming_error(stream))
294 		stop_stream(oxfw, stream);
295 
296 	err = snd_oxfw_stream_get_current_formation(oxfw, dir, &formation);
297 	if (err < 0)
298 		goto end;
299 	if (rate == 0)
300 		rate = formation.rate;
301 	if (pcm_channels == 0)
302 		pcm_channels = formation.pcm;
303 
304 	if ((formation.rate != rate) || (formation.pcm != pcm_channels)) {
305 		if (opposite != NULL) {
306 			err = check_connection_used_by_others(oxfw, opposite);
307 			if (err < 0)
308 				goto end;
309 			stop_stream(oxfw, opposite);
310 		}
311 		stop_stream(oxfw, stream);
312 
313 		err = set_stream_format(oxfw, stream, rate, pcm_channels);
314 		if (err < 0) {
315 			dev_err(&oxfw->unit->device,
316 				"fail to set stream format: %d\n", err);
317 			goto end;
318 		}
319 
320 		/* Start opposite stream if needed. */
321 		if (opposite && !amdtp_stream_running(opposite) &&
322 		    (opposite_substreams > 0)) {
323 			err = start_stream(oxfw, opposite, rate, 0);
324 			if (err < 0) {
325 				dev_err(&oxfw->unit->device,
326 					"fail to restart stream: %d\n", err);
327 				goto end;
328 			}
329 		}
330 	}
331 
332 	/* Start requested stream. */
333 	if (!amdtp_stream_running(stream)) {
334 		err = start_stream(oxfw, stream, rate, pcm_channels);
335 		if (err < 0)
336 			dev_err(&oxfw->unit->device,
337 				"fail to start stream: %d\n", err);
338 	}
339 end:
340 	return err;
341 }
342 
343 void snd_oxfw_stream_stop_simplex(struct snd_oxfw *oxfw,
344 				  struct amdtp_stream *stream)
345 {
346 	if (((stream == &oxfw->tx_stream) && (oxfw->capture_substreams > 0)) ||
347 	    ((stream == &oxfw->rx_stream) && (oxfw->playback_substreams > 0)))
348 		return;
349 
350 	stop_stream(oxfw, stream);
351 }
352 
353 /*
354  * This function should be called before starting the stream or after stopping
355  * the streams.
356  */
357 void snd_oxfw_stream_destroy_simplex(struct snd_oxfw *oxfw,
358 				     struct amdtp_stream *stream)
359 {
360 	struct cmp_connection *conn;
361 
362 	if (stream == &oxfw->tx_stream)
363 		conn = &oxfw->out_conn;
364 	else
365 		conn = &oxfw->in_conn;
366 
367 	amdtp_stream_destroy(stream);
368 	cmp_connection_destroy(conn);
369 }
370 
371 void snd_oxfw_stream_update_simplex(struct snd_oxfw *oxfw,
372 				    struct amdtp_stream *stream)
373 {
374 	struct cmp_connection *conn;
375 
376 	if (stream == &oxfw->tx_stream)
377 		conn = &oxfw->out_conn;
378 	else
379 		conn = &oxfw->in_conn;
380 
381 	if (cmp_connection_update(conn) < 0)
382 		stop_stream(oxfw, stream);
383 	else
384 		amdtp_stream_update(stream);
385 }
386 
387 int snd_oxfw_stream_get_current_formation(struct snd_oxfw *oxfw,
388 				enum avc_general_plug_dir dir,
389 				struct snd_oxfw_stream_formation *formation)
390 {
391 	u8 *format;
392 	unsigned int len;
393 	int err;
394 
395 	len = AVC_GENERIC_FRAME_MAXIMUM_BYTES;
396 	format = kmalloc(len, GFP_KERNEL);
397 	if (format == NULL)
398 		return -ENOMEM;
399 
400 	err = avc_stream_get_format_single(oxfw->unit, dir, 0, format, &len);
401 	if (err < 0)
402 		goto end;
403 	if (len < 3) {
404 		err = -EIO;
405 		goto end;
406 	}
407 
408 	err = snd_oxfw_stream_parse_format(format, formation);
409 end:
410 	kfree(format);
411 	return err;
412 }
413 
414 /*
415  * See Table 6.16 - AM824 Stream Format
416  *     Figure 6.19 - format_information field for AM824 Compound
417  * in AV/C Stream Format Information Specification 1.1 (Apr 2005, 1394TA)
418  * Also 'Clause 12 AM824 sequence adaption layers' in IEC 61883-6:2005
419  */
420 int snd_oxfw_stream_parse_format(u8 *format,
421 				 struct snd_oxfw_stream_formation *formation)
422 {
423 	unsigned int i, e, channels, type;
424 
425 	memset(formation, 0, sizeof(struct snd_oxfw_stream_formation));
426 
427 	/*
428 	 * this module can support a hierarchy combination that:
429 	 *  Root:	Audio and Music (0x90)
430 	 *  Level 1:	AM824 Compound  (0x40)
431 	 */
432 	if ((format[0] != 0x90) || (format[1] != 0x40))
433 		return -ENOSYS;
434 
435 	/* check the sampling rate */
436 	for (i = 0; i < ARRAY_SIZE(avc_stream_rate_table); i++) {
437 		if (format[2] == avc_stream_rate_table[i])
438 			break;
439 	}
440 	if (i == ARRAY_SIZE(avc_stream_rate_table))
441 		return -ENOSYS;
442 
443 	formation->rate = oxfw_rate_table[i];
444 
445 	for (e = 0; e < format[4]; e++) {
446 		channels = format[5 + e * 2];
447 		type = format[6 + e * 2];
448 
449 		switch (type) {
450 		/* IEC 60958 Conformant, currently handled as MBLA */
451 		case 0x00:
452 		/* Multi Bit Linear Audio (Raw) */
453 		case 0x06:
454 			formation->pcm += channels;
455 			break;
456 		/* MIDI Conformant */
457 		case 0x0d:
458 			formation->midi = channels;
459 			break;
460 		/* IEC 61937-3 to 7 */
461 		case 0x01:
462 		case 0x02:
463 		case 0x03:
464 		case 0x04:
465 		case 0x05:
466 		/* Multi Bit Linear Audio */
467 		case 0x07:	/* DVD-Audio */
468 		case 0x0c:	/* High Precision */
469 		/* One Bit Audio */
470 		case 0x08:	/* (Plain) Raw */
471 		case 0x09:	/* (Plain) SACD */
472 		case 0x0a:	/* (Encoded) Raw */
473 		case 0x0b:	/* (Encoded) SACD */
474 		/* SMPTE Time-Code conformant */
475 		case 0x0e:
476 		/* Sample Count */
477 		case 0x0f:
478 		/* Anciliary Data */
479 		case 0x10:
480 		/* Synchronization Stream (Stereo Raw audio) */
481 		case 0x40:
482 		/* Don't care */
483 		case 0xff:
484 		default:
485 			return -ENOSYS;	/* not supported */
486 		}
487 	}
488 
489 	if (formation->pcm  > AM824_MAX_CHANNELS_FOR_PCM ||
490 	    formation->midi > AM824_MAX_CHANNELS_FOR_MIDI)
491 		return -ENOSYS;
492 
493 	return 0;
494 }
495 
496 static int
497 assume_stream_formats(struct snd_oxfw *oxfw, enum avc_general_plug_dir dir,
498 		      unsigned int pid, u8 *buf, unsigned int *len,
499 		      u8 **formats)
500 {
501 	struct snd_oxfw_stream_formation formation;
502 	unsigned int i, eid;
503 	int err;
504 
505 	/* get format at current sampling rate */
506 	err = avc_stream_get_format_single(oxfw->unit, dir, pid, buf, len);
507 	if (err < 0) {
508 		dev_err(&oxfw->unit->device,
509 		"fail to get current stream format for isoc %s plug %d:%d\n",
510 			(dir == AVC_GENERAL_PLUG_DIR_IN) ? "in" : "out",
511 			pid, err);
512 		goto end;
513 	}
514 
515 	/* parse and set stream format */
516 	eid = 0;
517 	err = snd_oxfw_stream_parse_format(buf, &formation);
518 	if (err < 0)
519 		goto end;
520 
521 	formats[eid] = kmemdup(buf, *len, GFP_KERNEL);
522 	if (formats[eid] == NULL) {
523 		err = -ENOMEM;
524 		goto end;
525 	}
526 
527 	/* apply the format for each available sampling rate */
528 	for (i = 0; i < ARRAY_SIZE(oxfw_rate_table); i++) {
529 		if (formation.rate == oxfw_rate_table[i])
530 			continue;
531 
532 		err = avc_general_inquiry_sig_fmt(oxfw->unit,
533 						  oxfw_rate_table[i],
534 						  dir, pid);
535 		if (err < 0)
536 			continue;
537 
538 		eid++;
539 		formats[eid] = kmemdup(buf, *len, GFP_KERNEL);
540 		if (formats[eid] == NULL) {
541 			err = -ENOMEM;
542 			goto end;
543 		}
544 		formats[eid][2] = avc_stream_rate_table[i];
545 	}
546 
547 	err = 0;
548 	oxfw->assumed = true;
549 end:
550 	return err;
551 }
552 
553 static int fill_stream_formats(struct snd_oxfw *oxfw,
554 			       enum avc_general_plug_dir dir,
555 			       unsigned short pid)
556 {
557 	u8 *buf, **formats;
558 	unsigned int len, eid = 0;
559 	struct snd_oxfw_stream_formation dummy;
560 	int err;
561 
562 	buf = kmalloc(AVC_GENERIC_FRAME_MAXIMUM_BYTES, GFP_KERNEL);
563 	if (buf == NULL)
564 		return -ENOMEM;
565 
566 	if (dir == AVC_GENERAL_PLUG_DIR_OUT)
567 		formats = oxfw->tx_stream_formats;
568 	else
569 		formats = oxfw->rx_stream_formats;
570 
571 	/* get first entry */
572 	len = AVC_GENERIC_FRAME_MAXIMUM_BYTES;
573 	err = avc_stream_get_format_list(oxfw->unit, dir, 0, buf, &len, 0);
574 	if (err == -ENOSYS) {
575 		/* LIST subfunction is not implemented */
576 		len = AVC_GENERIC_FRAME_MAXIMUM_BYTES;
577 		err = assume_stream_formats(oxfw, dir, pid, buf, &len,
578 					    formats);
579 		goto end;
580 	} else if (err < 0) {
581 		dev_err(&oxfw->unit->device,
582 			"fail to get stream format %d for isoc %s plug %d:%d\n",
583 			eid, (dir == AVC_GENERAL_PLUG_DIR_IN) ? "in" : "out",
584 			pid, err);
585 		goto end;
586 	}
587 
588 	/* LIST subfunction is implemented */
589 	while (eid < SND_OXFW_STREAM_FORMAT_ENTRIES) {
590 		/* The format is too short. */
591 		if (len < 3) {
592 			err = -EIO;
593 			break;
594 		}
595 
596 		/* parse and set stream format */
597 		err = snd_oxfw_stream_parse_format(buf, &dummy);
598 		if (err < 0)
599 			break;
600 
601 		formats[eid] = kmemdup(buf, len, GFP_KERNEL);
602 		if (formats[eid] == NULL) {
603 			err = -ENOMEM;
604 			break;
605 		}
606 
607 		/* get next entry */
608 		len = AVC_GENERIC_FRAME_MAXIMUM_BYTES;
609 		err = avc_stream_get_format_list(oxfw->unit, dir, 0,
610 						 buf, &len, ++eid);
611 		/* No entries remained. */
612 		if (err == -EINVAL) {
613 			err = 0;
614 			break;
615 		} else if (err < 0) {
616 			dev_err(&oxfw->unit->device,
617 			"fail to get stream format %d for isoc %s plug %d:%d\n",
618 				eid, (dir == AVC_GENERAL_PLUG_DIR_IN) ? "in" :
619 									"out",
620 				pid, err);
621 			break;
622 		}
623 	}
624 end:
625 	kfree(buf);
626 	return err;
627 }
628 
629 int snd_oxfw_stream_discover(struct snd_oxfw *oxfw)
630 {
631 	u8 plugs[AVC_PLUG_INFO_BUF_BYTES];
632 	struct snd_oxfw_stream_formation formation;
633 	u8 *format;
634 	unsigned int i;
635 	int err;
636 
637 	/* the number of plugs for isoc in/out, ext in/out  */
638 	err = avc_general_get_plug_info(oxfw->unit, 0x1f, 0x07, 0x00, plugs);
639 	if (err < 0) {
640 		dev_err(&oxfw->unit->device,
641 		"fail to get info for isoc/external in/out plugs: %d\n",
642 			err);
643 		goto end;
644 	} else if ((plugs[0] == 0) && (plugs[1] == 0)) {
645 		err = -ENOSYS;
646 		goto end;
647 	}
648 
649 	/* use oPCR[0] if exists */
650 	if (plugs[1] > 0) {
651 		err = fill_stream_formats(oxfw, AVC_GENERAL_PLUG_DIR_OUT, 0);
652 		if (err < 0)
653 			goto end;
654 
655 		for (i = 0; i < SND_OXFW_STREAM_FORMAT_ENTRIES; i++) {
656 			format = oxfw->tx_stream_formats[i];
657 			if (format == NULL)
658 				continue;
659 			err = snd_oxfw_stream_parse_format(format, &formation);
660 			if (err < 0)
661 				continue;
662 
663 			/* Add one MIDI port. */
664 			if (formation.midi > 0)
665 				oxfw->midi_input_ports = 1;
666 		}
667 
668 		oxfw->has_output = true;
669 	}
670 
671 	/* use iPCR[0] if exists */
672 	if (plugs[0] > 0) {
673 		err = fill_stream_formats(oxfw, AVC_GENERAL_PLUG_DIR_IN, 0);
674 		if (err < 0)
675 			goto end;
676 
677 		for (i = 0; i < SND_OXFW_STREAM_FORMAT_ENTRIES; i++) {
678 			format = oxfw->rx_stream_formats[i];
679 			if (format == NULL)
680 				continue;
681 			err = snd_oxfw_stream_parse_format(format, &formation);
682 			if (err < 0)
683 				continue;
684 
685 			/* Add one MIDI port. */
686 			if (formation.midi > 0)
687 				oxfw->midi_output_ports = 1;
688 		}
689 	}
690 end:
691 	return err;
692 }
693 
694 void snd_oxfw_stream_lock_changed(struct snd_oxfw *oxfw)
695 {
696 	oxfw->dev_lock_changed = true;
697 	wake_up(&oxfw->hwdep_wait);
698 }
699 
700 int snd_oxfw_stream_lock_try(struct snd_oxfw *oxfw)
701 {
702 	int err;
703 
704 	spin_lock_irq(&oxfw->lock);
705 
706 	/* user land lock this */
707 	if (oxfw->dev_lock_count < 0) {
708 		err = -EBUSY;
709 		goto end;
710 	}
711 
712 	/* this is the first time */
713 	if (oxfw->dev_lock_count++ == 0)
714 		snd_oxfw_stream_lock_changed(oxfw);
715 	err = 0;
716 end:
717 	spin_unlock_irq(&oxfw->lock);
718 	return err;
719 }
720 
721 void snd_oxfw_stream_lock_release(struct snd_oxfw *oxfw)
722 {
723 	spin_lock_irq(&oxfw->lock);
724 
725 	if (WARN_ON(oxfw->dev_lock_count <= 0))
726 		goto end;
727 	if (--oxfw->dev_lock_count == 0)
728 		snd_oxfw_stream_lock_changed(oxfw);
729 end:
730 	spin_unlock_irq(&oxfw->lock);
731 }
732