sound/firewire/oxfw/oxfw-stream.c

   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 = DIV_ROUND_UP(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         int err;
 633
 634         /* the number of plugs for isoc in/out, ext in/out  */
 635         err = avc_general_get_plug_info(oxfw->unit, 0x1f, 0x07, 0x00, plugs);
 636         if (err < 0) {
 637                 dev_err(&oxfw->unit->device,
 638                 "fail to get info for isoc/external in/out plugs: %d\n",
 639                         err);
 640                 goto end;
 641         } else if ((plugs[0] == 0) && (plugs[1] == 0)) {
 642                 err = -ENOSYS;
 643                 goto end;
 644         }
 645
 646         /* use oPCR[0] if exists */
 647         if (plugs[1] > 0) {
 648                 err = fill_stream_formats(oxfw, AVC_GENERAL_PLUG_DIR_OUT, 0);
 649                 if (err < 0)
 650                         goto end;
 651                 oxfw->has_output = true;
 652         }
 653
 654         /* use iPCR[0] if exists */
 655         if (plugs[0] > 0)
 656                 err = fill_stream_formats(oxfw, AVC_GENERAL_PLUG_DIR_IN, 0);
 657 end:
 658         return err;
 659 }
 660
 661 void snd_oxfw_stream_lock_changed(struct snd_oxfw *oxfw)
 662 {
 663         oxfw->dev_lock_changed = true;
 664         wake_up(&oxfw->hwdep_wait);
 665 }
 666
 667 int snd_oxfw_stream_lock_try(struct snd_oxfw *oxfw)
 668 {
 669         int err;
 670
 671         spin_lock_irq(&oxfw->lock);
 672
 673         /* user land lock this */
 674         if (oxfw->dev_lock_count < 0) {
 675                 err = -EBUSY;
 676                 goto end;
 677         }
 678
 679         /* this is the first time */
 680         if (oxfw->dev_lock_count++ == 0)
 681                 snd_oxfw_stream_lock_changed(oxfw);
 682         err = 0;
 683 end:
 684         spin_unlock_irq(&oxfw->lock);
 685         return err;
 686 }
 687
 688 void snd_oxfw_stream_lock_release(struct snd_oxfw *oxfw)
 689 {
 690         spin_lock_irq(&oxfw->lock);
 691
 692         if (WARN_ON(oxfw->dev_lock_count <= 0))
 693                 goto end;
 694         if (--oxfw->dev_lock_count == 0)
 695                 snd_oxfw_stream_lock_changed(oxfw);
 696 end:
 697         spin_unlock_irq(&oxfw->lock);
 698 }