sound/firewire/amdtp.c

   1 /*
   2  * Audio and Music Data Transmission Protocol (IEC 61883-6) streams
   3  * with Common Isochronous Packet (IEC 61883-1) headers
   4  *
   5  * Copyright (c) Clemens Ladisch <clemens@ladisch.de>
   6  * Licensed under the terms of the GNU General Public License, version 2.
   7  */
   8
   9 #include <linux/device.h>
  10 #include <linux/err.h>
  11 #include <linux/firewire.h>
  12 #include <linux/module.h>
  13 #include <linux/slab.h>
  14 #include <sound/pcm.h>
  15 #include "amdtp.h"
  16
  17 #define TICKS_PER_CYCLE         3072
  18 #define CYCLES_PER_SECOND       8000
  19 #define TICKS_PER_SECOND        (TICKS_PER_CYCLE * CYCLES_PER_SECOND)
  20
  21 #define TRANSFER_DELAY_TICKS    0x2e00 /* 479.17 µs */
  22
  23 #define TAG_CIP                 1
  24
  25 #define CIP_EOH                 (1u << 31)
  26 #define CIP_FMT_AM              (0x10 << 24)
  27 #define AMDTP_FDF_AM824         (0 << 19)
  28 #define AMDTP_FDF_SFC_SHIFT     16
  29
  30 /* TODO: make these configurable */
  31 #define INTERRUPT_INTERVAL      16
  32 #define QUEUE_LENGTH            48
  33
  34 static void pcm_period_tasklet(unsigned long data);
  35
  36 /**
  37  * amdtp_out_stream_init - initialize an AMDTP output stream structure
  38  * @s: the AMDTP output stream to initialize
  39  * @unit: the target of the stream
  40  * @flags: the packet transmission method to use
  41  */
  42 int amdtp_out_stream_init(struct amdtp_out_stream *s, struct fw_unit *unit,
  43                           enum cip_out_flags flags)
  44 {
  45         s->unit = fw_unit_get(unit);
  46         s->flags = flags;
  47         s->context = ERR_PTR(-1);
  48         mutex_init(&s->mutex);
  49         tasklet_init(&s->period_tasklet, pcm_period_tasklet, (unsigned long)s);
  50         s->packet_index = 0;
  51
  52         return 0;
  53 }
  54 EXPORT_SYMBOL(amdtp_out_stream_init);
  55
  56 /**
  57  * amdtp_out_stream_destroy - free stream resources
  58  * @s: the AMDTP output stream to destroy
  59  */
  60 void amdtp_out_stream_destroy(struct amdtp_out_stream *s)
  61 {
  62         WARN_ON(amdtp_out_stream_running(s));
  63         mutex_destroy(&s->mutex);
  64         fw_unit_put(s->unit);
  65 }
  66 EXPORT_SYMBOL(amdtp_out_stream_destroy);
  67
  68 const unsigned int amdtp_syt_intervals[CIP_SFC_COUNT] = {
  69         [CIP_SFC_32000]  =  8,
  70         [CIP_SFC_44100]  =  8,
  71         [CIP_SFC_48000]  =  8,
  72         [CIP_SFC_88200]  = 16,
  73         [CIP_SFC_96000]  = 16,
  74         [CIP_SFC_176400] = 32,
  75         [CIP_SFC_192000] = 32,
  76 };
  77 EXPORT_SYMBOL(amdtp_syt_intervals);
  78
  79 /**
  80  * amdtp_out_stream_set_parameters - set stream parameters
  81  * @s: the AMDTP output stream to configure
  82  * @rate: the sample rate
  83  * @pcm_channels: the number of PCM samples in each data block, to be encoded
  84  *                as AM824 multi-bit linear audio
  85  * @midi_ports: the number of MIDI ports (i.e., MPX-MIDI Data Channels)
  86  *
  87  * The parameters must be set before the stream is started, and must not be
  88  * changed while the stream is running.
  89  */
  90 void amdtp_out_stream_set_parameters(struct amdtp_out_stream *s,
  91                                      unsigned int rate,
  92                                      unsigned int pcm_channels,
  93                                      unsigned int midi_ports)
  94 {
  95         static const unsigned int rates[] = {
  96                 [CIP_SFC_32000]  =  32000,
  97                 [CIP_SFC_44100]  =  44100,
  98                 [CIP_SFC_48000]  =  48000,
  99                 [CIP_SFC_88200]  =  88200,
 100                 [CIP_SFC_96000]  =  96000,
 101                 [CIP_SFC_176400] = 176400,
 102                 [CIP_SFC_192000] = 192000,
 103         };
 104         unsigned int sfc;
 105
 106         if (WARN_ON(amdtp_out_stream_running(s)))
 107                 return;
 108
 109         for (sfc = 0; sfc < CIP_SFC_COUNT; ++sfc)
 110                 if (rates[sfc] == rate)
 111                         goto sfc_found;
 112         WARN_ON(1);
 113         return;
 114
 115 sfc_found:
 116         s->dual_wire = (s->flags & CIP_HI_DUALWIRE) && sfc > CIP_SFC_96000;
 117         if (s->dual_wire) {
 118                 sfc -= 2;
 119                 rate /= 2;
 120                 pcm_channels *= 2;
 121         }
 122         s->sfc = sfc;
 123         s->data_block_quadlets = pcm_channels + DIV_ROUND_UP(midi_ports, 8);
 124         s->pcm_channels = pcm_channels;
 125         s->midi_ports = midi_ports;
 126
 127         s->syt_interval = amdtp_syt_intervals[sfc];
 128
 129         /* default buffering in the device */
 130         s->transfer_delay = TRANSFER_DELAY_TICKS - TICKS_PER_CYCLE;
 131         if (s->flags & CIP_BLOCKING)
 132                 /* additional buffering needed to adjust for no-data packets */
 133                 s->transfer_delay += TICKS_PER_SECOND * s->syt_interval / rate;
 134 }
 135 EXPORT_SYMBOL(amdtp_out_stream_set_parameters);
 136
 137 /**
 138  * amdtp_out_stream_get_max_payload - get the stream's packet size
 139  * @s: the AMDTP output stream
 140  *
 141  * This function must not be called before the stream has been configured
 142  * with amdtp_out_stream_set_parameters().
 143  */
 144 unsigned int amdtp_out_stream_get_max_payload(struct amdtp_out_stream *s)
 145 {
 146         return 8 + s->syt_interval * s->data_block_quadlets * 4;
 147 }
 148 EXPORT_SYMBOL(amdtp_out_stream_get_max_payload);
 149
 150 static void amdtp_write_s16(struct amdtp_out_stream *s,
 151                             struct snd_pcm_substream *pcm,
 152                             __be32 *buffer, unsigned int frames);
 153 static void amdtp_write_s32(struct amdtp_out_stream *s,
 154                             struct snd_pcm_substream *pcm,
 155                             __be32 *buffer, unsigned int frames);
 156 static void amdtp_write_s16_dualwire(struct amdtp_out_stream *s,
 157                                      struct snd_pcm_substream *pcm,
 158                                      __be32 *buffer, unsigned int frames);
 159 static void amdtp_write_s32_dualwire(struct amdtp_out_stream *s,
 160                                      struct snd_pcm_substream *pcm,
 161                                      __be32 *buffer, unsigned int frames);
 162
 163 /**
 164  * amdtp_out_stream_set_pcm_format - set the PCM format
 165  * @s: the AMDTP output stream to configure
 166  * @format: the format of the ALSA PCM device
 167  *
 168  * The sample format must be set after the other paramters (rate/PCM channels/
 169  * MIDI) and before the stream is started, and must not be changed while the
 170  * stream is running.
 171  */
 172 void amdtp_out_stream_set_pcm_format(struct amdtp_out_stream *s,
 173                                      snd_pcm_format_t format)
 174 {
 175         if (WARN_ON(amdtp_out_stream_running(s)))
 176                 return;
 177
 178         switch (format) {
 179         default:
 180                 WARN_ON(1);
 181                 /* fall through */
 182         case SNDRV_PCM_FORMAT_S16:
 183                 if (s->dual_wire)
 184                         s->transfer_samples = amdtp_write_s16_dualwire;
 185                 else
 186                         s->transfer_samples = amdtp_write_s16;
 187                 break;
 188         case SNDRV_PCM_FORMAT_S32:
 189                 if (s->dual_wire)
 190                         s->transfer_samples = amdtp_write_s32_dualwire;
 191                 else
 192                         s->transfer_samples = amdtp_write_s32;
 193                 break;
 194         }
 195 }
 196 EXPORT_SYMBOL(amdtp_out_stream_set_pcm_format);
 197
 198 /**
 199  * amdtp_out_stream_pcm_prepare - prepare PCM device for running
 200  * @s: the AMDTP output stream
 201  *
 202  * This function should be called from the PCM device's .prepare callback.
 203  */
 204 void amdtp_out_stream_pcm_prepare(struct amdtp_out_stream *s)
 205 {
 206         tasklet_kill(&s->period_tasklet);
 207         s->pcm_buffer_pointer = 0;
 208         s->pcm_period_pointer = 0;
 209         s->pointer_flush = true;
 210 }
 211 EXPORT_SYMBOL(amdtp_out_stream_pcm_prepare);
 212
 213 static unsigned int calculate_data_blocks(struct amdtp_out_stream *s)
 214 {
 215         unsigned int phase, data_blocks;
 216
 217         if (!cip_sfc_is_base_44100(s->sfc)) {
 218                 /* Sample_rate / 8000 is an integer, and precomputed. */
 219                 data_blocks = s->data_block_state;
 220         } else {
 221                 phase = s->data_block_state;
 222
 223                 /*
 224                  * This calculates the number of data blocks per packet so that
 225                  * 1) the overall rate is correct and exactly synchronized to
 226                  *    the bus clock, and
 227                  * 2) packets with a rounded-up number of blocks occur as early
 228                  *    as possible in the sequence (to prevent underruns of the
 229                  *    device's buffer).
 230                  */
 231                 if (s->sfc == CIP_SFC_44100)
 232                         /* 6 6 5 6 5 6 5 ... */
 233                         data_blocks = 5 + ((phase & 1) ^
 234                                            (phase == 0 || phase >= 40));
 235                 else
 236                         /* 12 11 11 11 11 ... or 23 22 22 22 22 ... */
 237                         data_blocks = 11 * (s->sfc >> 1) + (phase == 0);
 238                 if (++phase >= (80 >> (s->sfc >> 1)))
 239                         phase = 0;
 240                 s->data_block_state = phase;
 241         }
 242
 243         return data_blocks;
 244 }
 245
 246 static unsigned int calculate_syt(struct amdtp_out_stream *s,
 247                                   unsigned int cycle)
 248 {
 249         unsigned int syt_offset, phase, index, syt;
 250
 251         if (s->last_syt_offset < TICKS_PER_CYCLE) {
 252                 if (!cip_sfc_is_base_44100(s->sfc))
 253                         syt_offset = s->last_syt_offset + s->syt_offset_state;
 254                 else {
 255                 /*
 256                  * The time, in ticks, of the n'th SYT_INTERVAL sample is:
 257                  *   n * SYT_INTERVAL * 24576000 / sample_rate
 258                  * Modulo TICKS_PER_CYCLE, the difference between successive
 259                  * elements is about 1386.23.  Rounding the results of this
 260                  * formula to the SYT precision results in a sequence of
 261                  * differences that begins with:
 262                  *   1386 1386 1387 1386 1386 1386 1387 1386 1386 1386 1387 ...
 263                  * This code generates _exactly_ the same sequence.
 264                  */
 265                         phase = s->syt_offset_state;
 266                         index = phase % 13;
 267                         syt_offset = s->last_syt_offset;
 268                         syt_offset += 1386 + ((index && !(index & 3)) ||
 269                                               phase == 146);
 270                         if (++phase >= 147)
 271                                 phase = 0;
 272                         s->syt_offset_state = phase;
 273                 }
 274         } else
 275                 syt_offset = s->last_syt_offset - TICKS_PER_CYCLE;
 276         s->last_syt_offset = syt_offset;
 277
 278         if (syt_offset < TICKS_PER_CYCLE) {
 279                 syt_offset += s->transfer_delay;
 280                 syt = (cycle + syt_offset / TICKS_PER_CYCLE) << 12;
 281                 syt += syt_offset % TICKS_PER_CYCLE;
 282
 283                 return syt & 0xffff;
 284         } else {
 285                 return 0xffff; /* no info */
 286         }
 287 }
 288
 289 static void amdtp_write_s32(struct amdtp_out_stream *s,
 290                             struct snd_pcm_substream *pcm,
 291                             __be32 *buffer, unsigned int frames)
 292 {
 293         struct snd_pcm_runtime *runtime = pcm->runtime;
 294         unsigned int channels, remaining_frames, frame_step, i, c;
 295         const u32 *src;
 296
 297         channels = s->pcm_channels;
 298         src = (void *)runtime->dma_area +
 299                         frames_to_bytes(runtime, s->pcm_buffer_pointer);
 300         remaining_frames = runtime->buffer_size - s->pcm_buffer_pointer;
 301         frame_step = s->data_block_quadlets - channels;
 302
 303         for (i = 0; i < frames; ++i) {
 304                 for (c = 0; c < channels; ++c) {
 305                         *buffer = cpu_to_be32((*src >> 8) | 0x40000000);
 306                         src++;
 307                         buffer++;
 308                 }
 309                 buffer += frame_step;
 310                 if (--remaining_frames == 0)
 311                         src = (void *)runtime->dma_area;
 312         }
 313 }
 314
 315 static void amdtp_write_s16(struct amdtp_out_stream *s,
 316                             struct snd_pcm_substream *pcm,
 317                             __be32 *buffer, unsigned int frames)
 318 {
 319         struct snd_pcm_runtime *runtime = pcm->runtime;
 320         unsigned int channels, remaining_frames, frame_step, i, c;
 321         const u16 *src;
 322
 323         channels = s->pcm_channels;
 324         src = (void *)runtime->dma_area +
 325                         frames_to_bytes(runtime, s->pcm_buffer_pointer);
 326         remaining_frames = runtime->buffer_size - s->pcm_buffer_pointer;
 327         frame_step = s->data_block_quadlets - channels;
 328
 329         for (i = 0; i < frames; ++i) {
 330                 for (c = 0; c < channels; ++c) {
 331                         *buffer = cpu_to_be32((*src << 8) | 0x40000000);
 332                         src++;
 333                         buffer++;
 334                 }
 335                 buffer += frame_step;
 336                 if (--remaining_frames == 0)
 337                         src = (void *)runtime->dma_area;
 338         }
 339 }
 340
 341 static void amdtp_write_s32_dualwire(struct amdtp_out_stream *s,
 342                                      struct snd_pcm_substream *pcm,
 343                                      __be32 *buffer, unsigned int frames)
 344 {
 345         struct snd_pcm_runtime *runtime = pcm->runtime;
 346         unsigned int channels, frame_adjust_1, frame_adjust_2, i, c;
 347         const u32 *src;
 348
 349         channels = s->pcm_channels;
 350         src = (void *)runtime->dma_area +
 351                         s->pcm_buffer_pointer * (runtime->frame_bits / 8);
 352         frame_adjust_1 = channels - 1;
 353         frame_adjust_2 = 1 - (s->data_block_quadlets - channels);
 354
 355         channels /= 2;
 356         for (i = 0; i < frames; ++i) {
 357                 for (c = 0; c < channels; ++c) {
 358                         *buffer = cpu_to_be32((*src >> 8) | 0x40000000);
 359                         src++;
 360                         buffer += 2;
 361                 }
 362                 buffer -= frame_adjust_1;
 363                 for (c = 0; c < channels; ++c) {
 364                         *buffer = cpu_to_be32((*src >> 8) | 0x40000000);
 365                         src++;
 366                         buffer += 2;
 367                 }
 368                 buffer -= frame_adjust_2;
 369         }
 370 }
 371
 372 static void amdtp_write_s16_dualwire(struct amdtp_out_stream *s,
 373                                      struct snd_pcm_substream *pcm,
 374                                      __be32 *buffer, unsigned int frames)
 375 {
 376         struct snd_pcm_runtime *runtime = pcm->runtime;
 377         unsigned int channels, frame_adjust_1, frame_adjust_2, i, c;
 378         const u16 *src;
 379
 380         channels = s->pcm_channels;
 381         src = (void *)runtime->dma_area +
 382                         s->pcm_buffer_pointer * (runtime->frame_bits / 8);
 383         frame_adjust_1 = channels - 1;
 384         frame_adjust_2 = 1 - (s->data_block_quadlets - channels);
 385
 386         channels /= 2;
 387         for (i = 0; i < frames; ++i) {
 388                 for (c = 0; c < channels; ++c) {
 389                         *buffer = cpu_to_be32((*src << 8) | 0x40000000);
 390                         src++;
 391                         buffer += 2;
 392                 }
 393                 buffer -= frame_adjust_1;
 394                 for (c = 0; c < channels; ++c) {
 395                         *buffer = cpu_to_be32((*src << 8) | 0x40000000);
 396                         src++;
 397                         buffer += 2;
 398                 }
 399                 buffer -= frame_adjust_2;
 400         }
 401 }
 402
 403 static void amdtp_fill_pcm_silence(struct amdtp_out_stream *s,
 404                                    __be32 *buffer, unsigned int frames)
 405 {
 406         unsigned int i, c;
 407
 408         for (i = 0; i < frames; ++i) {
 409                 for (c = 0; c < s->pcm_channels; ++c)
 410                         buffer[c] = cpu_to_be32(0x40000000);
 411                 buffer += s->data_block_quadlets;
 412         }
 413 }
 414
 415 static void amdtp_fill_midi(struct amdtp_out_stream *s,
 416                             __be32 *buffer, unsigned int frames)
 417 {
 418         unsigned int i;
 419
 420         for (i = 0; i < frames; ++i)
 421                 buffer[s->pcm_channels + i * s->data_block_quadlets] =
 422                                                 cpu_to_be32(0x80000000);
 423 }
 424
 425 static void queue_out_packet(struct amdtp_out_stream *s, unsigned int cycle)
 426 {
 427         __be32 *buffer;
 428         unsigned int index, data_blocks, syt, ptr;
 429         struct snd_pcm_substream *pcm;
 430         struct fw_iso_packet packet;
 431         int err;
 432
 433         if (s->packet_index < 0)
 434                 return;
 435         index = s->packet_index;
 436
 437         /* this module generate empty packet for 'no data' */
 438         syt = calculate_syt(s, cycle);
 439         if (!(s->flags & CIP_BLOCKING))
 440                 data_blocks = calculate_data_blocks(s);
 441         else if (syt != 0xffff)
 442                 data_blocks = s->syt_interval;
 443         else
 444                 data_blocks = 0;
 445
 446         buffer = s->buffer.packets[index].buffer;
 447         buffer[0] = cpu_to_be32(ACCESS_ONCE(s->source_node_id_field) |
 448                                 (s->data_block_quadlets << 16) |
 449                                 s->data_block_counter);
 450         buffer[1] = cpu_to_be32(CIP_EOH | CIP_FMT_AM | AMDTP_FDF_AM824 |
 451                                 (s->sfc << AMDTP_FDF_SFC_SHIFT) | syt);
 452         buffer += 2;
 453
 454         pcm = ACCESS_ONCE(s->pcm);
 455         if (pcm)
 456                 s->transfer_samples(s, pcm, buffer, data_blocks);
 457         else
 458                 amdtp_fill_pcm_silence(s, buffer, data_blocks);
 459         if (s->midi_ports)
 460                 amdtp_fill_midi(s, buffer, data_blocks);
 461
 462         s->data_block_counter = (s->data_block_counter + data_blocks) & 0xff;
 463
 464         packet.payload_length = 8 + data_blocks * 4 * s->data_block_quadlets;
 465         packet.interrupt = IS_ALIGNED(index + 1, INTERRUPT_INTERVAL);
 466         packet.skip = 0;
 467         packet.tag = TAG_CIP;
 468         packet.sy = 0;
 469         packet.header_length = 0;
 470
 471         err = fw_iso_context_queue(s->context, &packet, &s->buffer.iso_buffer,
 472                                    s->buffer.packets[index].offset);
 473         if (err < 0) {
 474                 dev_err(&s->unit->device, "queueing error: %d\n", err);
 475                 s->packet_index = -1;
 476                 amdtp_out_stream_pcm_abort(s);
 477                 return;
 478         }
 479
 480         if (++index >= QUEUE_LENGTH)
 481                 index = 0;
 482         s->packet_index = index;
 483
 484         if (pcm) {
 485                 if (s->dual_wire)
 486                         data_blocks *= 2;
 487
 488                 ptr = s->pcm_buffer_pointer + data_blocks;
 489                 if (ptr >= pcm->runtime->buffer_size)
 490                         ptr -= pcm->runtime->buffer_size;
 491                 ACCESS_ONCE(s->pcm_buffer_pointer) = ptr;
 492
 493                 s->pcm_period_pointer += data_blocks;
 494                 if (s->pcm_period_pointer >= pcm->runtime->period_size) {
 495                         s->pcm_period_pointer -= pcm->runtime->period_size;
 496                         s->pointer_flush = false;
 497                         tasklet_hi_schedule(&s->period_tasklet);
 498                 }
 499         }
 500 }
 501
 502 static void pcm_period_tasklet(unsigned long data)
 503 {
 504         struct amdtp_out_stream *s = (void *)data;
 505         struct snd_pcm_substream *pcm = ACCESS_ONCE(s->pcm);
 506
 507         if (pcm)
 508                 snd_pcm_period_elapsed(pcm);
 509 }
 510
 511 static void out_packet_callback(struct fw_iso_context *context, u32 cycle,
 512                                 size_t header_length, void *header, void *data)
 513 {
 514         struct amdtp_out_stream *s = data;
 515         unsigned int i, packets = header_length / 4;
 516
 517         /*
 518          * Compute the cycle of the last queued packet.
 519          * (We need only the four lowest bits for the SYT, so we can ignore
 520          * that bits 0-11 must wrap around at 3072.)
 521          */
 522         cycle += QUEUE_LENGTH - packets;
 523
 524         for (i = 0; i < packets; ++i)
 525                 queue_out_packet(s, ++cycle);
 526         fw_iso_context_queue_flush(s->context);
 527 }
 528
 529 static int queue_initial_skip_packets(struct amdtp_out_stream *s)
 530 {
 531         struct fw_iso_packet skip_packet = {
 532                 .skip = 1,
 533         };
 534         unsigned int i;
 535         int err;
 536
 537         for (i = 0; i < QUEUE_LENGTH; ++i) {
 538                 skip_packet.interrupt = IS_ALIGNED(s->packet_index + 1,
 539                                                    INTERRUPT_INTERVAL);
 540                 err = fw_iso_context_queue(s->context, &skip_packet, NULL, 0);
 541                 if (err < 0)
 542                         return err;
 543                 if (++s->packet_index >= QUEUE_LENGTH)
 544                         s->packet_index = 0;
 545         }
 546
 547         return 0;
 548 }
 549
 550 /**
 551  * amdtp_out_stream_start - start sending packets
 552  * @s: the AMDTP output stream to start
 553  * @channel: the isochronous channel on the bus
 554  * @speed: firewire speed code
 555  *
 556  * The stream cannot be started until it has been configured with
 557  * amdtp_out_stream_set_parameters() and amdtp_out_stream_set_pcm_format(),
 558  * and it must be started before any PCM or MIDI device can be started.
 559  */
 560 int amdtp_out_stream_start(struct amdtp_out_stream *s, int channel, int speed)
 561 {
 562         static const struct {
 563                 unsigned int data_block;
 564                 unsigned int syt_offset;
 565         } initial_state[] = {
 566                 [CIP_SFC_32000]  = {  4, 3072 },
 567                 [CIP_SFC_48000]  = {  6, 1024 },
 568                 [CIP_SFC_96000]  = { 12, 1024 },
 569                 [CIP_SFC_192000] = { 24, 1024 },
 570                 [CIP_SFC_44100]  = {  0,   67 },
 571                 [CIP_SFC_88200]  = {  0,   67 },
 572                 [CIP_SFC_176400] = {  0,   67 },
 573         };
 574         int err;
 575
 576         mutex_lock(&s->mutex);
 577
 578         if (WARN_ON(amdtp_out_stream_running(s) ||
 579                     (!s->pcm_channels && !s->midi_ports))) {
 580                 err = -EBADFD;
 581                 goto err_unlock;
 582         }
 583
 584         s->data_block_state = initial_state[s->sfc].data_block;
 585         s->syt_offset_state = initial_state[s->sfc].syt_offset;
 586         s->last_syt_offset = TICKS_PER_CYCLE;
 587
 588         err = iso_packets_buffer_init(&s->buffer, s->unit, QUEUE_LENGTH,
 589                                       amdtp_out_stream_get_max_payload(s),
 590                                       DMA_TO_DEVICE);
 591         if (err < 0)
 592                 goto err_unlock;
 593
 594         s->context = fw_iso_context_create(fw_parent_device(s->unit)->card,
 595                                            FW_ISO_CONTEXT_TRANSMIT,
 596                                            channel, speed, 0,
 597                                            out_packet_callback, s);
 598         if (IS_ERR(s->context)) {
 599                 err = PTR_ERR(s->context);
 600                 if (err == -EBUSY)
 601                         dev_err(&s->unit->device,
 602                                 "no free output stream on this controller\n");
 603                 goto err_buffer;
 604         }
 605
 606         amdtp_out_stream_update(s);
 607
 608         s->packet_index = 0;
 609         s->data_block_counter = 0;
 610         err = queue_initial_skip_packets(s);
 611         if (err < 0)
 612                 goto err_context;
 613
 614         err = fw_iso_context_start(s->context, -1, 0, 0);
 615         if (err < 0)
 616                 goto err_context;
 617
 618         mutex_unlock(&s->mutex);
 619
 620         return 0;
 621
 622 err_context:
 623         fw_iso_context_destroy(s->context);
 624         s->context = ERR_PTR(-1);
 625 err_buffer:
 626         iso_packets_buffer_destroy(&s->buffer, s->unit);
 627 err_unlock:
 628         mutex_unlock(&s->mutex);
 629
 630         return err;
 631 }
 632 EXPORT_SYMBOL(amdtp_out_stream_start);
 633
 634 /**
 635  * amdtp_out_stream_pcm_pointer - get the PCM buffer position
 636  * @s: the AMDTP output stream that transports the PCM data
 637  *
 638  * Returns the current buffer position, in frames.
 639  */
 640 unsigned long amdtp_out_stream_pcm_pointer(struct amdtp_out_stream *s)
 641 {
 642         /* this optimization is allowed to be racy */
 643         if (s->pointer_flush)
 644                 fw_iso_context_flush_completions(s->context);
 645         else
 646                 s->pointer_flush = true;
 647
 648         return ACCESS_ONCE(s->pcm_buffer_pointer);
 649 }
 650 EXPORT_SYMBOL(amdtp_out_stream_pcm_pointer);
 651
 652 /**
 653  * amdtp_out_stream_update - update the stream after a bus reset
 654  * @s: the AMDTP output stream
 655  */
 656 void amdtp_out_stream_update(struct amdtp_out_stream *s)
 657 {
 658         ACCESS_ONCE(s->source_node_id_field) =
 659                 (fw_parent_device(s->unit)->card->node_id & 0x3f) << 24;
 660 }
 661 EXPORT_SYMBOL(amdtp_out_stream_update);
 662
 663 /**
 664  * amdtp_out_stream_stop - stop sending packets
 665  * @s: the AMDTP output stream to stop
 666  *
 667  * All PCM and MIDI devices of the stream must be stopped before the stream
 668  * itself can be stopped.
 669  */
 670 void amdtp_out_stream_stop(struct amdtp_out_stream *s)
 671 {
 672         mutex_lock(&s->mutex);
 673
 674         if (!amdtp_out_stream_running(s)) {
 675                 mutex_unlock(&s->mutex);
 676                 return;
 677         }
 678
 679         tasklet_kill(&s->period_tasklet);
 680         fw_iso_context_stop(s->context);
 681         fw_iso_context_destroy(s->context);
 682         s->context = ERR_PTR(-1);
 683         iso_packets_buffer_destroy(&s->buffer, s->unit);
 684
 685         mutex_unlock(&s->mutex);
 686 }
 687 EXPORT_SYMBOL(amdtp_out_stream_stop);
 688
 689 /**
 690  * amdtp_out_stream_pcm_abort - abort the running PCM device
 691  * @s: the AMDTP stream about to be stopped
 692  *
 693  * If the isochronous stream needs to be stopped asynchronously, call this
 694  * function first to stop the PCM device.
 695  */
 696 void amdtp_out_stream_pcm_abort(struct amdtp_out_stream *s)
 697 {
 698         struct snd_pcm_substream *pcm;
 699
 700         pcm = ACCESS_ONCE(s->pcm);
 701         if (pcm) {
 702                 snd_pcm_stream_lock_irq(pcm);
 703                 if (snd_pcm_running(pcm))
 704                         snd_pcm_stop(pcm, SNDRV_PCM_STATE_XRUN);
 705                 snd_pcm_stream_unlock_irq(pcm);
 706         }
 707 }
 708 EXPORT_SYMBOL(amdtp_out_stream_pcm_abort);