linux/sound/firewire/amdtp.c
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   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
  34static 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 */
  42int 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}
  54EXPORT_SYMBOL(amdtp_out_stream_init);
  55
  56/**
  57 * amdtp_out_stream_destroy - free stream resources
  58 * @s: the AMDTP output stream to destroy
  59 */
  60void 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}
  66EXPORT_SYMBOL(amdtp_out_stream_destroy);
  67
  68const 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};
  77EXPORT_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 */
  90void 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
 115sfc_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}
 135EXPORT_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 */
 144unsigned 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}
 148EXPORT_SYMBOL(amdtp_out_stream_get_max_payload);
 149
 150static void amdtp_write_s16(struct amdtp_out_stream *s,
 151                            struct snd_pcm_substream *pcm,
 152                            __be32 *buffer, unsigned int frames);
 153static void amdtp_write_s32(struct amdtp_out_stream *s,
 154                            struct snd_pcm_substream *pcm,
 155                            __be32 *buffer, unsigned int frames);
 156static void amdtp_write_s16_dualwire(struct amdtp_out_stream *s,
 157                                     struct snd_pcm_substream *pcm,
 158                                     __be32 *buffer, unsigned int frames);
 159static 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 */
 172void 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}
 196EXPORT_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 */
 204void 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}
 211EXPORT_SYMBOL(amdtp_out_stream_pcm_prepare);
 212
 213static 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
 246static 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
 289static 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
 315static 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
 341static 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
 372static 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
 403static 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
 415static 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
 425static 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
 502static 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
 511static 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
 529static 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 */
 560int 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
 622err_context:
 623        fw_iso_context_destroy(s->context);
 624        s->context = ERR_PTR(-1);
 625err_buffer:
 626        iso_packets_buffer_destroy(&s->buffer, s->unit);
 627err_unlock:
 628        mutex_unlock(&s->mutex);
 629
 630        return err;
 631}
 632EXPORT_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 */
 640unsigned 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}
 650EXPORT_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 */
 656void 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}
 661EXPORT_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 */
 670void 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}
 687EXPORT_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 */
 696void 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}
 708EXPORT_SYMBOL(amdtp_out_stream_pcm_abort);
 709