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1 /*

2 * Loopback soundcard

3 *

4 * Original code:

5 * Copyright (c) by Jaroslav Kysela <perex@perex.cz>

6 *

7 * More accurate positioning and full-duplex support:

8 * Copyright (c) Ahmet İnan <ainan at mathematik.uni-freiburg.de>

9 *

10 * Major (almost complete) rewrite:

11 * Copyright (c) by Takashi Iwai <tiwai@suse.de>

12 *

13 * A next major update in 2010 (separate timers for playback and capture):

14 * Copyright (c) Jaroslav Kysela <perex@perex.cz>

15 *

16 * This program is free software; you can redistribute it and/or modify

17 * it under the terms of the GNU General Public License as published by

18 * the Free Software Foundation; either version 2 of the License, or

19 * (at your option) any later version.

20 *

21 * This program is distributed in the hope that it will be useful,

22 * but WITHOUT ANY WARRANTY; without even the implied warranty of

23 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the

24 * GNU General Public License for more details.

25 *

26 * You should have received a copy of the GNU General Public License

27 * along with this program; if not, write to the Free Software

28 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA

29 *

30 */

31

32 #include <linux/init.h>

33 #include <linux/jiffies.h>

34 #include <linux/slab.h>

35 #include <linux/time.h>

36 #include <linux/wait.h>

37 #include <linux/module.h>

38 #include <linux/platform_device.h>

39 #include <sound/core.h>

40 #include <sound/control.h>

41 #include <sound/pcm.h>

42 #include <sound/info.h>

43 #include <sound/initval.h>

44

45 MODULE_AUTHOR("Jaroslav Kysela <perex@perex.cz>");

46 MODULE_DESCRIPTION("A loopback soundcard");

47 MODULE_LICENSE("GPL");

48 MODULE_SUPPORTED_DEVICE("{{ALSA,Loopback soundcard}}");

49

50 #define MAX_PCM_SUBSTREAMS 8

51

52 static int index[SNDRV_CARDS] = SNDRV_DEFAULT_IDX; /* Index 0-MAX */

53 static char *id[SNDRV_CARDS] = SNDRV_DEFAULT_STR; /* ID for this card */

54 static bool enable[SNDRV_CARDS] = {1, [1 ... (SNDRV_CARDS - 1)] = 0};

55 static int pcm_substreams[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS - 1)] = 8};

56 static int pcm_notify[SNDRV_CARDS];

57

58 module_param_array(index, int, NULL, 0444);

59 MODULE_PARM_DESC(index, "Index value for loopback soundcard.");

60 module_param_array(id, charp, NULL, 0444);

61 MODULE_PARM_DESC(id, "ID string for loopback soundcard.");

62 module_param_array(enable, bool, NULL, 0444);

63 MODULE_PARM_DESC(enable, "Enable this loopback soundcard.");

64 module_param_array(pcm_substreams, int, NULL, 0444);

65 MODULE_PARM_DESC(pcm_substreams, "PCM substreams # (1-8) for loopback driver.");

66 module_param_array(pcm_notify, int, NULL, 0444);

67 MODULE_PARM_DESC(pcm_notify, "Break capture when PCM format/rate/channels changes.");

68

69 #define NO_PITCH 100000

70

71 struct loopback_pcm;

72

73 struct loopback_cable {

74 spinlock_t lock;

75 struct loopback_pcm *streams[2];

76 struct snd_pcm_hardware hw;

77 /* flags */

78 unsigned int valid;

79 unsigned int running;

80 unsigned int pause;

81 };

82

83 struct loopback_setup {

84 unsigned int notify: 1;

85 unsigned int rate_shift;

86 unsigned int format;

87 unsigned int rate;

88 unsigned int channels;

89 struct snd_ctl_elem_id active_id;

90 struct snd_ctl_elem_id format_id;

91 struct snd_ctl_elem_id rate_id;

92 struct snd_ctl_elem_id channels_id;

93 };

94

95 struct loopback {

96 struct snd_card *card;

97 struct mutex cable_lock;

98 struct loopback_cable *cables[MAX_PCM_SUBSTREAMS][2];

99 struct snd_pcm *pcm[2];

100 struct loopback_setup setup[MAX_PCM_SUBSTREAMS][2];

101 };

102

103 struct loopback_pcm {

104 struct loopback *loopback;

105 struct snd_pcm_substream *substream;

106 struct loopback_cable *cable;

107 unsigned int pcm_buffer_size;

108 unsigned int buf_pos; /* position in buffer */

109 unsigned int silent_size;

110 /* PCM parameters */

111 unsigned int pcm_period_size;

112 unsigned int pcm_bps; /* bytes per second */

113 unsigned int pcm_salign; /* bytes per sample * channels */

114 unsigned int pcm_rate_shift; /* rate shift value */

115 /* flags */

116 unsigned int period_update_pending :1;

117 /* timer stuff */

118 unsigned int irq_pos; /* fractional IRQ position */

119 unsigned int period_size_frac;

120 unsigned int last_drift;

121 unsigned long last_jiffies;

122 struct timer_list timer;

123 };

124

125 static struct platform_device *devices[SNDRV_CARDS];

126

127 static inline unsigned int byte_pos(struct loopback_pcm *dpcm, unsigned int x)

128 {

129 if (dpcm->pcm_rate_shift == NO_PITCH) {

130 x /= HZ;

131 } else {

132 x = div_u64(NO_PITCH * (unsigned long long)x,

133 HZ * (unsigned long long)dpcm->pcm_rate_shift);

134 }

135 return x - (x % dpcm->pcm_salign);

136 }

137

138 static inline unsigned int frac_pos(struct loopback_pcm *dpcm, unsigned int x)

139 {

140 if (dpcm->pcm_rate_shift == NO_PITCH) { /* no pitch */

141 return x * HZ;

142 } else {

143 x = div_u64(dpcm->pcm_rate_shift * (unsigned long long)x * HZ,

144 NO_PITCH);

145 }

146 return x;

147 }

148

149 static inline struct loopback_setup *get_setup(struct loopback_pcm *dpcm)

150 {

151 int device = dpcm->substream->pstr->pcm->device;

152

153 if (dpcm->substream->stream == SNDRV_PCM_STREAM_PLAYBACK)

154 device ^= 1;

155 return &dpcm->loopback->setup[dpcm->substream->number][device];

156 }

157

158 static inline unsigned int get_notify(struct loopback_pcm *dpcm)

159 {

160 return get_setup(dpcm)->notify;

161 }

162

163 static inline unsigned int get_rate_shift(struct loopback_pcm *dpcm)

164 {

165 return get_setup(dpcm)->rate_shift;

166 }

167

168 static void loopback_timer_start(struct loopback_pcm *dpcm)

169 {

170 unsigned long tick;

171 unsigned int rate_shift = get_rate_shift(dpcm);

172

173 if (rate_shift != dpcm->pcm_rate_shift) {

174 dpcm->pcm_rate_shift = rate_shift;

175 dpcm->period_size_frac = frac_pos(dpcm, dpcm->pcm_period_size);

176 }

177 if (dpcm->period_size_frac <= dpcm->irq_pos) {

178 dpcm->irq_pos %= dpcm->period_size_frac;

179 dpcm->period_update_pending = 1;

180 }

181 tick = dpcm->period_size_frac - dpcm->irq_pos;

182 tick = (tick + dpcm->pcm_bps - 1) / dpcm->pcm_bps;

183 dpcm->timer.expires = jiffies + tick;

184 add_timer(&dpcm->timer);

185 }

186

187 static inline void loopback_timer_stop(struct loopback_pcm *dpcm)

188 {

189 del_timer(&dpcm->timer);

190 dpcm->timer.expires = 0;

191 }

192

193 #define CABLE_VALID_PLAYBACK (1 << SNDRV_PCM_STREAM_PLAYBACK)

194 #define CABLE_VALID_CAPTURE (1 << SNDRV_PCM_STREAM_CAPTURE)

195 #define CABLE_VALID_BOTH (CABLE_VALID_PLAYBACK|CABLE_VALID_CAPTURE)

196

197 static int loopback_check_format(struct loopback_cable *cable, int stream)

198 {

199 struct snd_pcm_runtime *runtime, *cruntime;

200 struct loopback_setup *setup;

201 struct snd_card *card;

202 int check;

203

204 if (cable->valid != CABLE_VALID_BOTH) {

205 if (stream == SNDRV_PCM_STREAM_PLAYBACK)

206 goto __notify;

207 return 0;

208 }

209 runtime = cable->streams[SNDRV_PCM_STREAM_PLAYBACK]->

210 substream->runtime;

211 cruntime = cable->streams[SNDRV_PCM_STREAM_CAPTURE]->

212 substream->runtime;

213 check = runtime->format != cruntime->format ||

214 runtime->rate != cruntime->rate ||

215 runtime->channels != cruntime->channels;

216 if (!check)

217 return 0;

218 if (stream == SNDRV_PCM_STREAM_CAPTURE) {

219 return -EIO;

220 } else {

221 snd_pcm_stop(cable->streams[SNDRV_PCM_STREAM_CAPTURE]->

222 substream, SNDRV_PCM_STATE_DRAINING);

223 __notify:

224 runtime = cable->streams[SNDRV_PCM_STREAM_PLAYBACK]->

225 substream->runtime;

226 setup = get_setup(cable->streams[SNDRV_PCM_STREAM_PLAYBACK]);

227 card = cable->streams[SNDRV_PCM_STREAM_PLAYBACK]->loopback->card;

228 if (setup->format != runtime->format) {

229 snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_VALUE,

230 &setup->format_id);

231 setup->format = runtime->format;

232 }

233 if (setup->rate != runtime->rate) {

234 snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_VALUE,

235 &setup->rate_id);

236 setup->rate = runtime->rate;

237 }

238 if (setup->channels != runtime->channels) {

239 snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_VALUE,

240 &setup->channels_id);

241 setup->channels = runtime->channels;

242 }

243 }

244 return 0;

245 }

246

247 static void loopback_active_notify(struct loopback_pcm *dpcm)

248 {

249 snd_ctl_notify(dpcm->loopback->card,

250 SNDRV_CTL_EVENT_MASK_VALUE,

251 &get_setup(dpcm)->active_id);

252 }

253

254 static int loopback_trigger(struct snd_pcm_substream *substream, int cmd)

255 {

256 struct snd_pcm_runtime *runtime = substream->runtime;

257 struct loopback_pcm *dpcm = runtime->private_data;

258 struct loopback_cable *cable = dpcm->cable;

259 int err, stream = 1 << substream->stream;

260

261 switch (cmd) {

262 case SNDRV_PCM_TRIGGER_START:

263 err = loopback_check_format(cable, substream->stream);

264 if (err < 0)

265 return err;

266 dpcm->last_jiffies = jiffies;

267 dpcm->pcm_rate_shift = 0;

268 dpcm->last_drift = 0;

269 spin_lock(&cable->lock);

270 cable->running |= stream;

271 cable->pause &= ~stream;

272 spin_unlock(&cable->lock);

273 loopback_timer_start(dpcm);

274 if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)

275 loopback_active_notify(dpcm);

276 break;

277 case SNDRV_PCM_TRIGGER_STOP:

278 spin_lock(&cable->lock);

279 cable->running &= ~stream;

280 cable->pause &= ~stream;

281 spin_unlock(&cable->lock);

282 loopback_timer_stop(dpcm);

283 if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)

284 loopback_active_notify(dpcm);

285 break;

286 case SNDRV_PCM_TRIGGER_PAUSE_PUSH:

287 spin_lock(&cable->lock);

288 cable->pause |= stream;

289 spin_unlock(&cable->lock);

290 loopback_timer_stop(dpcm);

291 break;

292 case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:

293 spin_lock(&cable->lock);

294 dpcm->last_jiffies = jiffies;

295 cable->pause &= ~stream;

296 spin_unlock(&cable->lock);

297 loopback_timer_start(dpcm);

298 break;

299 default:

300 return -EINVAL;

301 }

302 return 0;

303 }

304

305 static void params_change_substream(struct loopback_pcm *dpcm,

306 struct snd_pcm_runtime *runtime)

307 {

308 struct snd_pcm_runtime *dst_runtime;

309

310 if (dpcm == NULL || dpcm->substream == NULL)

311 return;

312 dst_runtime = dpcm->substream->runtime;

313 if (dst_runtime == NULL)

314 return;

315 dst_runtime->hw = dpcm->cable->hw;

316 }

317

318 static void params_change(struct snd_pcm_substream *substream)

319 {

320 struct snd_pcm_runtime *runtime = substream->runtime;

321 struct loopback_pcm *dpcm = runtime->private_data;

322 struct loopback_cable *cable = dpcm->cable;

323

324 cable->hw.formats = (1ULL << runtime->format);

325 cable->hw.rate_min = runtime->rate;

326 cable->hw.rate_max = runtime->rate;

327 cable->hw.channels_min = runtime->channels;

328 cable->hw.channels_max = runtime->channels;

329 params_change_substream(cable->streams[SNDRV_PCM_STREAM_PLAYBACK],

330 runtime);

331 params_change_substream(cable->streams[SNDRV_PCM_STREAM_CAPTURE],

332 runtime);

333 }

334

335 static int loopback_prepare(struct snd_pcm_substream *substream)

336 {

337 struct snd_pcm_runtime *runtime = substream->runtime;

338 struct loopback_pcm *dpcm = runtime->private_data;

339 struct loopback_cable *cable = dpcm->cable;

340 int bps, salign;

341

342 salign = (snd_pcm_format_width(runtime->format) *

343 runtime->channels) / 8;

344 bps = salign * runtime->rate;

345 if (bps <= 0 || salign <= 0)

346 return -EINVAL;

347

348 dpcm->buf_pos = 0;

349 dpcm->pcm_buffer_size = frames_to_bytes(runtime, runtime->buffer_size);

350 if (substream->stream == SNDRV_PCM_STREAM_CAPTURE) {

351 /* clear capture buffer */

352 dpcm->silent_size = dpcm->pcm_buffer_size;

353 snd_pcm_format_set_silence(runtime->format, runtime->dma_area,

354 runtime->buffer_size * runtime->channels);

355 }

356

357 dpcm->irq_pos = 0;

358 dpcm->period_update_pending = 0;

359 dpcm->pcm_bps = bps;

360 dpcm->pcm_salign = salign;

361 dpcm->pcm_period_size = frames_to_bytes(runtime, runtime->period_size);

362

363 mutex_lock(&dpcm->loopback->cable_lock);

364 if (!(cable->valid & ~(1 << substream->stream)) ||

365 (get_setup(dpcm)->notify &&

366 substream->stream == SNDRV_PCM_STREAM_PLAYBACK))

367 params_change(substream);

368 cable->valid |= 1 << substream->stream;

369 mutex_unlock(&dpcm->loopback->cable_lock);

370

371 return 0;

372 }

373

374 static void clear_capture_buf(struct loopback_pcm *dpcm, unsigned int bytes)

375 {

376 struct snd_pcm_runtime *runtime = dpcm->substream->runtime;

377 char *dst = runtime->dma_area;

378 unsigned int dst_off = dpcm->buf_pos;

379

380 if (dpcm->silent_size >= dpcm->pcm_buffer_size)

381 return;

382 if (dpcm->silent_size + bytes > dpcm->pcm_buffer_size)

383 bytes = dpcm->pcm_buffer_size - dpcm->silent_size;

384

385 for (;;) {

386 unsigned int size = bytes;

387 if (dst_off + size > dpcm->pcm_buffer_size)

388 size = dpcm->pcm_buffer_size - dst_off;

389 snd_pcm_format_set_silence(runtime->format, dst + dst_off,

390 bytes_to_frames(runtime, size) *

391 runtime->channels);

392 dpcm->silent_size += size;

393 bytes -= size;

394 if (!bytes)

395 break;

396 dst_off = 0;

397 }

398 }

399

400 static void copy_play_buf(struct loopback_pcm *play,

401 struct loopback_pcm *capt,

402 unsigned int bytes)

403 {

404 struct snd_pcm_runtime *runtime = play->substream->runtime;

405 char *src = runtime->dma_area;

406 char *dst = capt->substream->runtime->dma_area;

407 unsigned int src_off = play->buf_pos;

408 unsigned int dst_off = capt->buf_pos;

409 unsigned int clear_bytes = 0;

410

411 /* check if playback is draining, trim the capture copy size

412 * when our pointer is at the end of playback ring buffer */

413 if (runtime->status->state == SNDRV_PCM_STATE_DRAINING &&

414 snd_pcm_playback_hw_avail(runtime) < runtime->buffer_size) {

415 snd_pcm_uframes_t appl_ptr, appl_ptr1, diff;

416 appl_ptr = appl_ptr1 = runtime->control->appl_ptr;

417 appl_ptr1 -= appl_ptr1 % runtime->buffer_size;

418 appl_ptr1 += play->buf_pos / play->pcm_salign;

419 if (appl_ptr < appl_ptr1)

420 appl_ptr1 -= runtime->buffer_size;

421 diff = (appl_ptr - appl_ptr1) * play->pcm_salign;

422 if (diff < bytes) {

423 clear_bytes = bytes - diff;

424 bytes = diff;

425 }

426 }

427

428 for (;;) {

429 unsigned int size = bytes;

430 if (src_off + size > play->pcm_buffer_size)

431 size = play->pcm_buffer_size - src_off;

432 if (dst_off + size > capt->pcm_buffer_size)

433 size = capt->pcm_buffer_size - dst_off;

434 memcpy(dst + dst_off, src + src_off, size);

435 capt->silent_size = 0;

436 bytes -= size;

437 if (!bytes)

438 break;

439 src_off = (src_off + size) % play->pcm_buffer_size;

440 dst_off = (dst_off + size) % capt->pcm_buffer_size;

441 }

442

443 if (clear_bytes > 0) {

444 clear_capture_buf(capt, clear_bytes);

445 capt->silent_size = 0;

446 }

447 }

448

449 static inline unsigned int bytepos_delta(struct loopback_pcm *dpcm,

450 unsigned int jiffies_delta)

451 {

452 unsigned long last_pos;

453 unsigned int delta;

454

455 last_pos = byte_pos(dpcm, dpcm->irq_pos);

456 dpcm->irq_pos += jiffies_delta * dpcm->pcm_bps;

457 delta = byte_pos(dpcm, dpcm->irq_pos) - last_pos;

458 if (delta >= dpcm->last_drift)

459 delta -= dpcm->last_drift;

460 dpcm->last_drift = 0;

461 if (dpcm->irq_pos >= dpcm->period_size_frac) {

462 dpcm->irq_pos %= dpcm->period_size_frac;

463 dpcm->period_update_pending = 1;

464 }

465 return delta;

466 }

467

468 static inline void bytepos_finish(struct loopback_pcm *dpcm,

469 unsigned int delta)

470 {

471 dpcm->buf_pos += delta;

472 dpcm->buf_pos %= dpcm->pcm_buffer_size;

473 }

474

475 static unsigned int loopback_pos_update(struct loopback_cable *cable)

476 {

477 struct loopback_pcm *dpcm_play =

478 cable->streams[SNDRV_PCM_STREAM_PLAYBACK];

479 struct loopback_pcm *dpcm_capt =

480 cable->streams[SNDRV_PCM_STREAM_CAPTURE];

481 unsigned long delta_play = 0, delta_capt = 0;

482 unsigned int running, count1, count2;

483 unsigned long flags;

484

485 spin_lock_irqsave(&cable->lock, flags);

486 running = cable->running ^ cable->pause;

487 if (running & (1 << SNDRV_PCM_STREAM_PLAYBACK)) {

488 delta_play = jiffies - dpcm_play->last_jiffies;

489 dpcm_play->last_jiffies += delta_play;

490 }

491

492 if (running & (1 << SNDRV_PCM_STREAM_CAPTURE)) {

493 delta_capt = jiffies - dpcm_capt->last_jiffies;

494 dpcm_capt->last_jiffies += delta_capt;

495 }

496

497 if (delta_play == 0 && delta_capt == 0)

498 goto unlock;

499

500 if (delta_play > delta_capt) {

501 count1 = bytepos_delta(dpcm_play, delta_play - delta_capt);

502 bytepos_finish(dpcm_play, count1);

503 delta_play = delta_capt;

504 } else if (delta_play < delta_capt) {

505 count1 = bytepos_delta(dpcm_capt, delta_capt - delta_play);

506 clear_capture_buf(dpcm_capt, count1);

507 bytepos_finish(dpcm_capt, count1);

508 delta_capt = delta_play;

509 }

510

511 if (delta_play == 0 && delta_capt == 0)

512 goto unlock;

513

514 /* note delta_capt == delta_play at this moment */

515 count1 = bytepos_delta(dpcm_play, delta_play);

516 count2 = bytepos_delta(dpcm_capt, delta_capt);

517 if (count1 < count2) {

518 dpcm_capt->last_drift = count2 - count1;

519 count1 = count2;

520 } else if (count1 > count2) {

521 dpcm_play->last_drift = count1 - count2;

522 }

523 copy_play_buf(dpcm_play, dpcm_capt, count1);

524 bytepos_finish(dpcm_play, count1);

525 bytepos_finish(dpcm_capt, count1);

526 unlock:

527 spin_unlock_irqrestore(&cable->lock, flags);

528 return running;

529 }

530

531 static void loopback_timer_function(unsigned long data)

532 {

533 struct loopback_pcm *dpcm = (struct loopback_pcm *)data;

534 unsigned int running;

535

536 running = loopback_pos_update(dpcm->cable);

537 if (running & (1 << dpcm->substream->stream)) {

538 loopback_timer_start(dpcm);

539 if (dpcm->period_update_pending) {

540 dpcm->period_update_pending = 0;

541 snd_pcm_period_elapsed(dpcm->substream);

542 }

543 }

544 }

545

546 static snd_pcm_uframes_t loopback_pointer(struct snd_pcm_substream *substream)

547 {

548 struct snd_pcm_runtime *runtime = substream->runtime;

549 struct loopback_pcm *dpcm = runtime->private_data;

550

551 loopback_pos_update(dpcm->cable);

552 return bytes_to_frames(runtime, dpcm->buf_pos);

553 }

554

555 static struct snd_pcm_hardware loopback_pcm_hardware =

556 {

557 .info = (SNDRV_PCM_INFO_INTERLEAVED | SNDRV_PCM_INFO_MMAP |

558 SNDRV_PCM_INFO_MMAP_VALID | SNDRV_PCM_INFO_PAUSE),

559 .formats = (SNDRV_PCM_FMTBIT_S16_LE | SNDRV_PCM_FMTBIT_S16_BE |

560 SNDRV_PCM_FMTBIT_S32_LE | SNDRV_PCM_FMTBIT_S32_BE |

561 SNDRV_PCM_FMTBIT_FLOAT_LE | SNDRV_PCM_FMTBIT_FLOAT_BE),

562 .rates = SNDRV_PCM_RATE_CONTINUOUS | SNDRV_PCM_RATE_8000_192000,

563 .rate_min = 8000,

564 .rate_max = 192000,

565 .channels_min = 1,

566 .channels_max = 32,

567 .buffer_bytes_max = 2 * 1024 * 1024,

568 .period_bytes_min = 64,

569 /* note check overflow in frac_pos() using pcm_rate_shift before

570 changing period_bytes_max value */

571 .period_bytes_max = 1024 * 1024,

572 .periods_min = 1,

573 .periods_max = 1024,

574 .fifo_size = 0,

575 };

576

577 static void loopback_runtime_free(struct snd_pcm_runtime *runtime)

578 {

579 struct loopback_pcm *dpcm = runtime->private_data;

580 kfree(dpcm);

581 }

582

583 static int loopback_hw_params(struct snd_pcm_substream *substream,

584 struct snd_pcm_hw_params *params)

585 {

586 return snd_pcm_lib_alloc_vmalloc_buffer(substream,

587 params_buffer_bytes(params));

588 }

589

590 static int loopback_hw_free(struct snd_pcm_substream *substream)

591 {

592 struct snd_pcm_runtime *runtime = substream->runtime;

593 struct loopback_pcm *dpcm = runtime->private_data;

594 struct loopback_cable *cable = dpcm->cable;

595

596 mutex_lock(&dpcm->loopback->cable_lock);

597 cable->valid &= ~(1 << substream->stream);

598 mutex_unlock(&dpcm->loopback->cable_lock);

599 return snd_pcm_lib_free_vmalloc_buffer(substream);

600 }

601

602 static unsigned int get_cable_index(struct snd_pcm_substream *substream)

603 {

604 if (!substream->pcm->device)

605 return substream->stream;

606 else

607 return !substream->stream;

608 }

609

610 static int rule_format(struct snd_pcm_hw_params *params,

611 struct snd_pcm_hw_rule *rule)

612 {

613

614 struct snd_pcm_hardware *hw = rule->private;

615 struct snd_mask *maskp = hw_param_mask(params, rule->var);

616

617 maskp->bits[0] &= (u_int32_t)hw->formats;

618 maskp->bits[1] &= (u_int32_t)(hw->formats >> 32);

619 memset(maskp->bits + 2, 0, (SNDRV_MASK_MAX-64) / 8); /* clear rest */

620 if (! maskp->bits[0] && ! maskp->bits[1])

621 return -EINVAL;

622 return 0;

623 }

624

625 static int rule_rate(struct snd_pcm_hw_params *params,

626 struct snd_pcm_hw_rule *rule)

627 {

628 struct snd_pcm_hardware *hw = rule->private;

629 struct snd_interval t;

630

631 t.min = hw->rate_min;

632 t.max = hw->rate_max;

633 t.openmin = t.openmax = 0;

634 t.integer = 0;

635 return snd_interval_refine(hw_param_interval(params, rule->var), &t);

636 }

637

638 static int rule_channels(struct snd_pcm_hw_params *params,

639 struct snd_pcm_hw_rule *rule)

640 {

641 struct snd_pcm_hardware *hw = rule->private;

642 struct snd_interval t;

643

644 t.min = hw->channels_min;

645 t.max = hw->channels_max;

646 t.openmin = t.openmax = 0;

647 t.integer = 0;

648 return snd_interval_refine(hw_param_interval(params, rule->var), &t);

649 }

650

651 static int loopback_open(struct snd_pcm_substream *substream)

652 {

653 struct snd_pcm_runtime *runtime = substream->runtime;

654 struct loopback *loopback = substream->private_data;

655 struct loopback_pcm *dpcm;

656 struct loopback_cable *cable;

657 int err = 0;

658 int dev = get_cable_index(substream);

659

660 mutex_lock(&loopback->cable_lock);

661 dpcm = kzalloc(sizeof(*dpcm), GFP_KERNEL);

662 if (!dpcm) {

663 err = -ENOMEM;

664 goto unlock;

665 }

666 dpcm->loopback = loopback;

667 dpcm->substream = substream;

668 setup_timer(&dpcm->timer, loopback_timer_function,

669 (unsigned long)dpcm);

670

671 cable = loopback->cables[substream->number][dev];

672 if (!cable) {

673 cable = kzalloc(sizeof(*cable), GFP_KERNEL);

674 if (!cable) {

675 kfree(dpcm);

676 err = -ENOMEM;

677 goto unlock;

678 }

679 spin_lock_init(&cable->lock);

680 cable->hw = loopback_pcm_hardware;

681 loopback->cables[substream->number][dev] = cable;

682 }

683 dpcm->cable = cable;

684 cable->streams[substream->stream] = dpcm;

685

686 snd_pcm_hw_constraint_integer(runtime, SNDRV_PCM_HW_PARAM_PERIODS);

687

688 /* use dynamic rules based on actual runtime->hw values */

689 /* note that the default rules created in the PCM midlevel code */

690 /* are cached -> they do not reflect the actual state */

691 err = snd_pcm_hw_rule_add(runtime, 0,

692 SNDRV_PCM_HW_PARAM_FORMAT,

693 rule_format, &runtime->hw,

694 SNDRV_PCM_HW_PARAM_FORMAT, -1);

695 if (err < 0)

696 goto unlock;

697 err = snd_pcm_hw_rule_add(runtime, 0,

698 SNDRV_PCM_HW_PARAM_RATE,

699 rule_rate, &runtime->hw,

700 SNDRV_PCM_HW_PARAM_RATE, -1);

701 if (err < 0)

702 goto unlock;

703 err = snd_pcm_hw_rule_add(runtime, 0,

704 SNDRV_PCM_HW_PARAM_CHANNELS,

705 rule_channels, &runtime->hw,

706 SNDRV_PCM_HW_PARAM_CHANNELS, -1);

707 if (err < 0)

708 goto unlock;

709

710 runtime->private_data = dpcm;

711 runtime->private_free = loopback_runtime_free;

712 if (get_notify(dpcm))

713 runtime->hw = loopback_pcm_hardware;

714 else

715 runtime->hw = cable->hw;

716 unlock:

717 mutex_unlock(&loopback->cable_lock);

718 return err;

719 }

720

721 static int loopback_close(struct snd_pcm_substream *substream)

722 {

723 struct loopback *loopback = substream->private_data;

724 struct loopback_pcm *dpcm = substream->runtime->private_data;

725 struct loopback_cable *cable;

726 int dev = get_cable_index(substream);

727

728 loopback_timer_stop(dpcm);

729 mutex_lock(&loopback->cable_lock);

730 cable = loopback->cables[substream->number][dev];

731 if (cable->streams[!substream->stream]) {

732 /* other stream is still alive */

733 cable->streams[substream->stream] = NULL;

734 } else {

735 /* free the cable */

736 loopback->cables[substream->number][dev] = NULL;

737 kfree(cable);

738 }

739 mutex_unlock(&loopback->cable_lock);

740 return 0;

741 }

742

743 static struct snd_pcm_ops loopback_playback_ops = {

744 .open = loopback_open,

745 .close = loopback_close,

746 .ioctl = snd_pcm_lib_ioctl,

747 .hw_params = loopback_hw_params,

748 .hw_free = loopback_hw_free,

749 .prepare = loopback_prepare,

750 .trigger = loopback_trigger,

751 .pointer = loopback_pointer,

752 .page = snd_pcm_lib_get_vmalloc_page,

753 .mmap = snd_pcm_lib_mmap_vmalloc,

754 };

755

756 static struct snd_pcm_ops loopback_capture_ops = {

757 .open = loopback_open,

758 .close = loopback_close,

759 .ioctl = snd_pcm_lib_ioctl,

760 .hw_params = loopback_hw_params,

761 .hw_free = loopback_hw_free,

762 .prepare = loopback_prepare,

763 .trigger = loopback_trigger,

764 .pointer = loopback_pointer,

765 .page = snd_pcm_lib_get_vmalloc_page,

766 .mmap = snd_pcm_lib_mmap_vmalloc,

767 };

768

769 static int __devinit loopback_pcm_new(struct loopback *loopback,

770 int device, int substreams)

771 {

772 struct snd_pcm *pcm;

773 int err;

774

775 err = snd_pcm_new(loopback->card, "Loopback PCM", device,

776 substreams, substreams, &pcm);

777 if (err < 0)

778 return err;

779 snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_PLAYBACK, &loopback_playback_ops);

780 snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_CAPTURE, &loopback_capture_ops);

781

782 pcm->private_data = loopback;

783 pcm->info_flags = 0;

784 strcpy(pcm->name, "Loopback PCM");

785

786 loopback->pcm[device] = pcm;

787 return 0;

788 }

789

790 static int loopback_rate_shift_info(struct snd_kcontrol *kcontrol,

791 struct snd_ctl_elem_info *uinfo)

792 {

793 uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER;

794 uinfo->count = 1;

795 uinfo->value.integer.min = 80000;

796 uinfo->value.integer.max = 120000;

797 uinfo->value.integer.step = 1;

798 return 0;

799 }

800

801 static int loopback_rate_shift_get(struct snd_kcontrol *kcontrol,

802 struct snd_ctl_elem_value *ucontrol)

803 {

804 struct loopback *loopback = snd_kcontrol_chip(kcontrol);

805

806 ucontrol->value.integer.value[0] =

807 loopback->setup[kcontrol->id.subdevice]

808 [kcontrol->id.device].rate_shift;

809 return 0;

810 }

811

812 static int loopback_rate_shift_put(struct snd_kcontrol *kcontrol,

813 struct snd_ctl_elem_value *ucontrol)

814 {

815 struct loopback *loopback = snd_kcontrol_chip(kcontrol);

816 unsigned int val;

817 int change = 0;

818

819 val = ucontrol->value.integer.value[0];

820 if (val < 80000)

821 val = 80000;

822 if (val > 120000)

823 val = 120000;

824 mutex_lock(&loopback->cable_lock);

825 if (val != loopback->setup[kcontrol->id.subdevice]

826 [kcontrol->id.device].rate_shift) {

827 loopback->setup[kcontrol->id.subdevice]

828 [kcontrol->id.device].rate_shift = val;

829 change = 1;

830 }

831 mutex_unlock(&loopback->cable_lock);

832 return change;

833 }

834

835 static int loopback_notify_get(struct snd_kcontrol *kcontrol,

836 struct snd_ctl_elem_value *ucontrol)

837 {

838 struct loopback *loopback = snd_kcontrol_chip(kcontrol);

839

840 ucontrol->value.integer.value[0] =

841 loopback->setup[kcontrol->id.subdevice]

842 [kcontrol->id.device].notify;

843 return 0;

844 }

845

846 static int loopback_notify_put(struct snd_kcontrol *kcontrol,

847 struct snd_ctl_elem_value *ucontrol)

848 {

849 struct loopback *loopback = snd_kcontrol_chip(kcontrol);

850 unsigned int val;

851 int change = 0;

852

853 val = ucontrol->value.integer.value[0] ? 1 : 0;

854 if (val != loopback->setup[kcontrol->id.subdevice]

855 [kcontrol->id.device].notify) {

856 loopback->setup[kcontrol->id.subdevice]

857 [kcontrol->id.device].notify = val;

858 change = 1;

859 }

860 return change;

861 }

862

863 static int loopback_active_get(struct snd_kcontrol *kcontrol,

864 struct snd_ctl_elem_value *ucontrol)

865 {

866 struct loopback *loopback = snd_kcontrol_chip(kcontrol);

867 struct loopback_cable *cable = loopback->cables

868 [kcontrol->id.subdevice][kcontrol->id.device ^ 1];

869 unsigned int val = 0;

870

871 if (cable != NULL)

872 val = (cable->running & (1 << SNDRV_PCM_STREAM_PLAYBACK)) ?

873 1 : 0;

874 ucontrol->value.integer.value[0] = val;

875 return 0;

876 }

877

878 static int loopback_format_info(struct snd_kcontrol *kcontrol,

879 struct snd_ctl_elem_info *uinfo)

880 {

881 uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER;

882 uinfo->count = 1;

883 uinfo->value.integer.min = 0;

884 uinfo->value.integer.max = SNDRV_PCM_FORMAT_LAST;

885 uinfo->value.integer.step = 1;

886 return 0;

887 }

888

889 static int loopback_format_get(struct snd_kcontrol *kcontrol,

890 struct snd_ctl_elem_value *ucontrol)

891 {

892 struct loopback *loopback = snd_kcontrol_chip(kcontrol);

893

894 ucontrol->value.integer.value[0] =

895 loopback->setup[kcontrol->id.subdevice]

896 [kcontrol->id.device].format;

897 return 0;

898 }

899

900 static int loopback_rate_info(struct snd_kcontrol *kcontrol,

901 struct snd_ctl_elem_info *uinfo)

902 {

903 uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER;

904 uinfo->count = 1;

905 uinfo->value.integer.min = 0;

906 uinfo->value.integer.max = 192000;

907 uinfo->value.integer.step = 1;

908 return 0;

909 }

910

911 static int loopback_rate_get(struct snd_kcontrol *kcontrol,

912 struct snd_ctl_elem_value *ucontrol)

913 {

914 struct loopback *loopback = snd_kcontrol_chip(kcontrol);

915

916 ucontrol->value.integer.value[0] =

917 loopback->setup[kcontrol->id.subdevice]

918 [kcontrol->id.device].rate;

919 return 0;

920 }

921

922 static int loopback_channels_info(struct snd_kcontrol *kcontrol,

923 struct snd_ctl_elem_info *uinfo)

924 {

925 uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER;

926 uinfo->count = 1;

927 uinfo->value.integer.min = 1;

928 uinfo->value.integer.max = 1024;

929 uinfo->value.integer.step = 1;

930 return 0;

931 }

932

933 static int loopback_channels_get(struct snd_kcontrol *kcontrol,

934 struct snd_ctl_elem_value *ucontrol)

935 {

936 struct loopback *loopback = snd_kcontrol_chip(kcontrol);

937

938 ucontrol->value.integer.value[0] =

939 loopback->setup[kcontrol->id.subdevice]

940 [kcontrol->id.device].channels;

941 return 0;

942 }

943

944 static struct snd_kcontrol_new loopback_controls[] __devinitdata = {

945 {

946 .iface = SNDRV_CTL_ELEM_IFACE_PCM,

947 .name = "PCM Rate Shift 100000",

948 .info = loopback_rate_shift_info,

949 .get = loopback_rate_shift_get,

950 .put = loopback_rate_shift_put,

951 },

952 {

953 .iface = SNDRV_CTL_ELEM_IFACE_PCM,

954 .name = "PCM Notify",

955 .info = snd_ctl_boolean_mono_info,

956 .get = loopback_notify_get,

957 .put = loopback_notify_put,

958 },

959 #define ACTIVE_IDX 2

960 {

961 .access = SNDRV_CTL_ELEM_ACCESS_READ,

962 .iface = SNDRV_CTL_ELEM_IFACE_PCM,

963 .name = "PCM Slave Active",

964 .info = snd_ctl_boolean_mono_info,

965 .get = loopback_active_get,

966 },

967 #define FORMAT_IDX 3

968 {

969 .access = SNDRV_CTL_ELEM_ACCESS_READ,

970 .iface = SNDRV_CTL_ELEM_IFACE_PCM,

971 .name = "PCM Slave Format",

972 .info = loopback_format_info,

973 .get = loopback_format_get

974 },

975 #define RATE_IDX 4

976 {

977 .access = SNDRV_CTL_ELEM_ACCESS_READ,

978 .iface = SNDRV_CTL_ELEM_IFACE_PCM,

979 .name = "PCM Slave Rate",

980 .info = loopback_rate_info,

981 .get = loopback_rate_get

982 },

983 #define CHANNELS_IDX 5

984 {

985 .access = SNDRV_CTL_ELEM_ACCESS_READ,

986 .iface = SNDRV_CTL_ELEM_IFACE_PCM,

987 .name = "PCM Slave Channels",

988 .info = loopback_channels_info,

989 .get = loopback_channels_get

990 }

991 };

992

993 static int __devinit loopback_mixer_new(struct loopback *loopback, int notify)

994 {

995 struct snd_card *card = loopback->card;

996 struct snd_pcm *pcm;

997 struct snd_kcontrol *kctl;

998 struct loopback_setup *setup;

999 int err, dev, substr, substr_count, idx;

1000

1001 strcpy(card->mixername, "Loopback Mixer");

1002 for (dev = 0; dev < 2; dev++) {

1003 pcm = loopback->pcm[dev];

1004 substr_count =

1005 pcm->streams[SNDRV_PCM_STREAM_CAPTURE].substream_count;

1006 for (substr = 0; substr < substr_count; substr++) {

1007 setup = &loopback->setup[substr][dev];

1008 setup->notify = notify;

1009 setup->rate_shift = NO_PITCH;

1010 setup->format = SNDRV_PCM_FORMAT_S16_LE;

1011 setup->rate = 48000;

1012 setup->channels = 2;

1013 for (idx = 0; idx < ARRAY_SIZE(loopback_controls);

1014 idx++) {

1015 kctl = snd_ctl_new1(&loopback_controls[idx],

1016 loopback);

1017 if (!kctl)

1018 return -ENOMEM;

1019 kctl->id.device = dev;

1020 kctl->id.subdevice = substr;

1021 switch (idx) {

1022 case ACTIVE_IDX:

1023 setup->active_id = kctl->id;

1024 break;

1025 case FORMAT_IDX:

1026 setup->format_id = kctl->id;

1027 break;

1028 case RATE_IDX:

1029 setup->rate_id = kctl->id;

1030 break;

1031 case CHANNELS_IDX:

1032 setup->channels_id = kctl->id;

1033 break;

1034 default:

1035 break;

1036 }

1037 err = snd_ctl_add(card, kctl);

1038 if (err < 0)

1039 return err;

1040 }

1041 }

1042 }

1043 return 0;

1044 }

1045

1046 #ifdef CONFIG_PROC_FS

1047

1048 static void print_dpcm_info(struct snd_info_buffer *buffer,

1049 struct loopback_pcm *dpcm,

1050 const char *id)

1051 {

1052 snd_iprintf(buffer, " %s\n", id);

1053 if (dpcm == NULL) {

1054 snd_iprintf(buffer, " inactive\n");

1055 return;

1056 }

1057 snd_iprintf(buffer, " buffer_size:\t%u\n", dpcm->pcm_buffer_size);

1058 snd_iprintf(buffer, " buffer_pos:\t\t%u\n", dpcm->buf_pos);

1059 snd_iprintf(buffer, " silent_size:\t%u\n", dpcm->silent_size);

1060 snd_iprintf(buffer, " period_size:\t%u\n", dpcm->pcm_period_size);

1061 snd_iprintf(buffer, " bytes_per_sec:\t%u\n", dpcm->pcm_bps);

1062 snd_iprintf(buffer, " sample_align:\t%u\n", dpcm->pcm_salign);

1063 snd_iprintf(buffer, " rate_shift:\t\t%u\n", dpcm->pcm_rate_shift);

1064 snd_iprintf(buffer, " update_pending:\t%u\n",

1065 dpcm->period_update_pending);

1066 snd_iprintf(buffer, " irq_pos:\t\t%u\n", dpcm->irq_pos);

1067 snd_iprintf(buffer, " period_frac:\t%u\n", dpcm->period_size_frac);

1068 snd_iprintf(buffer, " last_jiffies:\t%lu (%lu)\n",

1069 dpcm->last_jiffies, jiffies);

1070 snd_iprintf(buffer, " timer_expires:\t%lu\n", dpcm->timer.expires);

1071 }

1072

1073 static void print_substream_info(struct snd_info_buffer *buffer,

1074 struct loopback *loopback,

1075 int sub,

1076 int num)

1077 {

1078 struct loopback_cable *cable = loopback->cables[sub][num];

1079

1080 snd_iprintf(buffer, "Cable %i substream %i:\n", num, sub);

1081 if (cable == NULL) {

1082 snd_iprintf(buffer, " inactive\n");

1083 return;

1084 }

1085 snd_iprintf(buffer, " valid: %u\n", cable->valid);

1086 snd_iprintf(buffer, " running: %u\n", cable->running);

1087 snd_iprintf(buffer, " pause: %u\n", cable->pause);

1088 print_dpcm_info(buffer, cable->streams[0], "Playback");

1089 print_dpcm_info(buffer, cable->streams[1], "Capture");

1090 }

1091

1092 static void print_cable_info(struct snd_info_entry *entry,

1093 struct snd_info_buffer *buffer)

1094 {

1095 struct loopback *loopback = entry->private_data;

1096 int sub, num;

1097

1098 mutex_lock(&loopback->cable_lock);

1099 num = entry->name[strlen(entry->name)-1];

1100 num = num == '0' ? 0 : 1;

1101 for (sub = 0; sub < MAX_PCM_SUBSTREAMS; sub++)

1102 print_substream_info(buffer, loopback, sub, num);

1103 mutex_unlock(&loopback->cable_lock);

1104 }

1105

1106 static int __devinit loopback_proc_new(struct loopback *loopback, int cidx)

1107 {

1108 char name[32];

1109 struct snd_info_entry *entry;

1110 int err;

1111

1112 snprintf(name, sizeof(name), "cable#%d", cidx);

1113 err = snd_card_proc_new(loopback->card, name, &entry);

1114 if (err < 0)

1115 return err;

1116

1117 snd_info_set_text_ops(entry, loopback, print_cable_info);

1118 return 0;

1119 }

1120

1121 #else /* !CONFIG_PROC_FS */

1122

1123 #define loopback_proc_new(loopback, cidx) do { } while (0)

1124

1125 #endif

1126

1127 static int __devinit loopback_probe(struct platform_device *devptr)

1128 {

1129 struct snd_card *card;

1130 struct loopback *loopback;

1131 int dev = devptr->id;

1132 int err;

1133

1134 err = snd_card_create(index[dev], id[dev], THIS_MODULE,

1135 sizeof(struct loopback), &card);

1136 if (err < 0)

1137 return err;

1138 loopback = card->private_data;

1139

1140 if (pcm_substreams[dev] < 1)

1141 pcm_substreams[dev] = 1;

1142 if (pcm_substreams[dev] > MAX_PCM_SUBSTREAMS)

1143 pcm_substreams[dev] = MAX_PCM_SUBSTREAMS;

1144

1145 loopback->card = card;

1146 mutex_init(&loopback->cable_lock);

1147

1148 err = loopback_pcm_new(loopback, 0, pcm_substreams[dev]);

1149 if (err < 0)

1150 goto __nodev;

1151 err = loopback_pcm_new(loopback, 1, pcm_substreams[dev]);

1152 if (err < 0)

1153 goto __nodev;

1154 err = loopback_mixer_new(loopback, pcm_notify[dev] ? 1 : 0);

1155 if (err < 0)

1156 goto __nodev;

1157 loopback_proc_new(loopback, 0);

1158 loopback_proc_new(loopback, 1);

1159 strcpy(card->driver, "Loopback");

1160 strcpy(card->shortname, "Loopback");

1161 sprintf(card->longname, "Loopback %i", dev + 1);

1162 err = snd_card_register(card);

1163 if (!err) {

1164 platform_set_drvdata(devptr, card);

1165 return 0;

1166 }

1167 __nodev:

1168 snd_card_free(card);

1169 return err;

1170 }

1171

1172 static int __devexit loopback_remove(struct platform_device *devptr)

1173 {

1174 snd_card_free(platform_get_drvdata(devptr));

1175 platform_set_drvdata(devptr, NULL);

1176 return 0;

1177 }

1178

1179 #ifdef CONFIG_PM

1180 static int loopback_suspend(struct platform_device *pdev,

1181 pm_message_t state)

1182 {

1183 struct snd_card *card = platform_get_drvdata(pdev);

1184 struct loopback *loopback = card->private_data;

1185

1186 snd_power_change_state(card, SNDRV_CTL_POWER_D3hot);

1187

1188 snd_pcm_suspend_all(loopback->pcm[0]);

1189 snd_pcm_suspend_all(loopback->pcm[1]);

1190 return 0;

1191 }

1192

1193 static int loopback_resume(struct platform_device *pdev)

1194 {

1195 struct snd_card *card = platform_get_drvdata(pdev);

1196

1197 snd_power_change_state(card, SNDRV_CTL_POWER_D0);

1198 return 0;

1199 }

1200 #endif

1201

1202 #define SND_LOOPBACK_DRIVER "snd_aloop"

1203

1204 static struct platform_driver loopback_driver = {

1205 .probe = loopback_probe,

1206 .remove = __devexit_p(loopback_remove),

1207 #ifdef CONFIG_PM

1208 .suspend = loopback_suspend,

1209 .resume = loopback_resume,

1210 #endif

1211 .driver = {

1212 .name = SND_LOOPBACK_DRIVER,

1213 .owner = THIS_MODULE,

1214 },

1215 };

1216

1217 static void loopback_unregister_all(void)

1218 {

1219 int i;

1220

1221 for (i = 0; i < ARRAY_SIZE(devices); ++i)

1222 platform_device_unregister(devices[i]);

1223 platform_driver_unregister(&loopback_driver);

1224 }

1225

1226 static int __init alsa_card_loopback_init(void)

1227 {

1228 int i, err, cards;

1229

1230 err = platform_driver_register(&loopback_driver);

1231 if (err < 0)

1232 return err;

1233

1234

1235 cards = 0;

1236 for (i = 0; i < SNDRV_CARDS; i++) {

1237 struct platform_device *device;

1238 if (!enable[i])

1239 continue;

1240 device = platform_device_register_simple(SND_LOOPBACK_DRIVER,

1241 i, NULL, 0);

1242 if (IS_ERR(device))

1243 continue;

1244 if (!platform_get_drvdata(device)) {

1245 platform_device_unregister(device);

1246 continue;

1247 }

1248 devices[i] = device;

1249 cards++;

1250 }

1251 if (!cards) {

1252 #ifdef MODULE

1253 printk(KERN_ERR "aloop: No loopback enabled\n");

1254 #endif

1255 loopback_unregister_all();

1256 return -ENODEV;

1257 }

1258 return 0;

1259 }

1260

1261 static void __exit alsa_card_loopback_exit(void)

1262 {

1263 loopback_unregister_all();

1264 }

1265

1266 module_init(alsa_card_loopback_init)

1267 module_exit(alsa_card_loopback_exit)