amdtp.c

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/*
 * Audio and Music Data Transmission Protocol (IEC 61883-6) streams
 * with Common Isochronous Packet (IEC 61883-1) headers
 *
 * Copyright (c) Clemens Ladisch <[email protected]>
 * Licensed under the terms of the GNU General Public License, version 2.
 */

#include <linux/device.h>
#include <linux/err.h>
#include <linux/firewire.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <sound/pcm.h>
#include "amdtp.h"

#define TICKS_PER_CYCLE     3072
#define CYCLES_PER_SECOND   8000
#define TICKS_PER_SECOND    (TICKS_PER_CYCLE * CYCLES_PER_SECOND)

#define TRANSFER_DELAY_TICKS    0x2e00 /* 479.17 µs */

#define TAG_CIP         1

#define CIP_EOH         (1u << 31)
#define CIP_FMT_AM      (0x10 << 24)
#define AMDTP_FDF_AM824     (0 << 19)
#define AMDTP_FDF_SFC_SHIFT 16

/* TODO: make these configurable */
#define INTERRUPT_INTERVAL  16
#define QUEUE_LENGTH        48

static void pcm_period_tasklet(unsigned long data);

int amdtp_out_stream_init(struct amdtp_out_stream *s, struct fw_unit *unit,
              enum cip_out_flags flags)
{
    if (flags != CIP_NONBLOCKING)
        return -EINVAL;

    s->unit = fw_unit_get(unit);
    s->flags = flags;
    s->context = ERR_PTR(-1);
    mutex_init(&s->mutex);
    tasklet_init(&s->period_tasklet, pcm_period_tasklet, (unsigned long)s);
    s->packet_index = 0;

    return 0;
}
EXPORT_SYMBOL(amdtp_out_stream_init);

void amdtp_out_stream_destroy(struct amdtp_out_stream *s)
{
    WARN_ON(!IS_ERR(s->context));
    mutex_destroy(&s->mutex);
    fw_unit_put(s->unit);
}
EXPORT_SYMBOL(amdtp_out_stream_destroy);

void amdtp_out_stream_set_rate(struct amdtp_out_stream *s, unsigned int rate)
{
    static const struct {
        unsigned int rate;
        unsigned int syt_interval;
    } rate_info[] = {
        [CIP_SFC_32000]  = {  32000,  8, },
        [CIP_SFC_44100]  = {  44100,  8, },
        [CIP_SFC_48000]  = {  48000,  8, },
        [CIP_SFC_88200]  = {  88200, 16, },
        [CIP_SFC_96000]  = {  96000, 16, },
        [CIP_SFC_176400] = { 176400, 32, },
        [CIP_SFC_192000] = { 192000, 32, },
    };
    unsigned int sfc;

    if (WARN_ON(!IS_ERR(s->context)))
        return;

    for (sfc = 0; sfc < ARRAY_SIZE(rate_info); ++sfc)
        if (rate_info[sfc].rate == rate) {
            s->sfc = sfc;
            s->syt_interval = rate_info[sfc].syt_interval;
            return;
        }
    WARN_ON(1);
}
EXPORT_SYMBOL(amdtp_out_stream_set_rate);

unsigned int amdtp_out_stream_get_max_payload(struct amdtp_out_stream *s)
{
    static const unsigned int max_data_blocks[] = {
        [CIP_SFC_32000]  =  4,
        [CIP_SFC_44100]  =  6,
        [CIP_SFC_48000]  =  6,
        [CIP_SFC_88200]  = 12,
        [CIP_SFC_96000]  = 12,
        [CIP_SFC_176400] = 23,
        [CIP_SFC_192000] = 24,
    };

    s->data_block_quadlets = s->pcm_channels;
    s->data_block_quadlets += DIV_ROUND_UP(s->midi_ports, 8);

    return 8 + max_data_blocks[s->sfc] * 4 * s->data_block_quadlets;
}
EXPORT_SYMBOL(amdtp_out_stream_get_max_payload);

static void amdtp_write_s16(struct amdtp_out_stream *s,
                struct snd_pcm_substream *pcm,
                __be32 *buffer, unsigned int frames);
static void amdtp_write_s32(struct amdtp_out_stream *s,
                struct snd_pcm_substream *pcm,
                __be32 *buffer, unsigned int frames);

void amdtp_out_stream_set_pcm_format(struct amdtp_out_stream *s,
                     snd_pcm_format_t format)
{
    if (WARN_ON(!IS_ERR(s->context)))
        return;

    switch (format) {
    default:
        WARN_ON(1);
        /* fall through */
    case SNDRV_PCM_FORMAT_S16:
        s->transfer_samples = amdtp_write_s16;
        break;
    case SNDRV_PCM_FORMAT_S32:
        s->transfer_samples = amdtp_write_s32;
        break;
    }
}
EXPORT_SYMBOL(amdtp_out_stream_set_pcm_format);

void amdtp_out_stream_pcm_prepare(struct amdtp_out_stream *s)
{
    tasklet_kill(&s->period_tasklet);
    s->pcm_buffer_pointer = 0;
    s->pcm_period_pointer = 0;
    s->pointer_flush = true;
}
EXPORT_SYMBOL(amdtp_out_stream_pcm_prepare);

static unsigned int calculate_data_blocks(struct amdtp_out_stream *s)
{
    unsigned int phase, data_blocks;

    if (!cip_sfc_is_base_44100(s->sfc)) {
        /* Sample_rate / 8000 is an integer, and precomputed. */
        data_blocks = s->data_block_state;
    } else {
        phase = s->data_block_state;

        /*
         * This calculates the number of data blocks per packet so that
         * 1) the overall rate is correct and exactly synchronized to
         *    the bus clock, and
         * 2) packets with a rounded-up number of blocks occur as early
         *    as possible in the sequence (to prevent underruns of the
         *    device's buffer).
         */
        if (s->sfc == CIP_SFC_44100)
            /* 6 6 5 6 5 6 5 ... */
            data_blocks = 5 + ((phase & 1) ^
                       (phase == 0 || phase >= 40));
        else
            /* 12 11 11 11 11 ... or 23 22 22 22 22 ... */
            data_blocks = 11 * (s->sfc >> 1) + (phase == 0);
        if (++phase >= (80 >> (s->sfc >> 1)))
            phase = 0;
        s->data_block_state = phase;
    }

    return data_blocks;
}

static unsigned int calculate_syt(struct amdtp_out_stream *s,
                  unsigned int cycle)
{
    unsigned int syt_offset, phase, index, syt;

    if (s->last_syt_offset < TICKS_PER_CYCLE) {
        if (!cip_sfc_is_base_44100(s->sfc))
            syt_offset = s->last_syt_offset + s->syt_offset_state;
        else {
        /*
         * The time, in ticks, of the n'th SYT_INTERVAL sample is:
         *   n * SYT_INTERVAL * 24576000 / sample_rate
         * Modulo TICKS_PER_CYCLE, the difference between successive
         * elements is about 1386.23.  Rounding the results of this
         * formula to the SYT precision results in a sequence of
         * differences that begins with:
         *   1386 1386 1387 1386 1386 1386 1387 1386 1386 1386 1387 ...
         * This code generates _exactly_ the same sequence.
         */
            phase = s->syt_offset_state;
            index = phase % 13;
            syt_offset = s->last_syt_offset;
            syt_offset += 1386 + ((index && !(index & 3)) ||
                          phase == 146);
            if (++phase >= 147)
                phase = 0;
            s->syt_offset_state = phase;
        }
    } else
        syt_offset = s->last_syt_offset - TICKS_PER_CYCLE;
    s->last_syt_offset = syt_offset;

    if (syt_offset < TICKS_PER_CYCLE) {
        syt_offset += TRANSFER_DELAY_TICKS - TICKS_PER_CYCLE;
        syt = (cycle + syt_offset / TICKS_PER_CYCLE) << 12;
        syt += syt_offset % TICKS_PER_CYCLE;

        return syt & 0xffff;
    } else {
        return 0xffff; /* no info */
    }
}

static void amdtp_write_s32(struct amdtp_out_stream *s,
                struct snd_pcm_substream *pcm,
                __be32 *buffer, unsigned int frames)
{
    struct snd_pcm_runtime *runtime = pcm->runtime;
    unsigned int channels, remaining_frames, frame_step, i, c;
    const u32 *src;

    channels = s->pcm_channels;
    src = (void *)runtime->dma_area +
            s->pcm_buffer_pointer * (runtime->frame_bits / 8);
    remaining_frames = runtime->buffer_size - s->pcm_buffer_pointer;
    frame_step = s->data_block_quadlets - channels;

    for (i = 0; i < frames; ++i) {
        for (c = 0; c < channels; ++c) {
            *buffer = cpu_to_be32((*src >> 8) | 0x40000000);
            src++;
            buffer++;
        }
        buffer += frame_step;
        if (--remaining_frames == 0)
            src = (void *)runtime->dma_area;
    }
}

static void amdtp_write_s16(struct amdtp_out_stream *s,
                struct snd_pcm_substream *pcm,
                __be32 *buffer, unsigned int frames)
{
    struct snd_pcm_runtime *runtime = pcm->runtime;
    unsigned int channels, remaining_frames, frame_step, i, c;
    const u16 *src;

    channels = s->pcm_channels;
    src = (void *)runtime->dma_area +
            s->pcm_buffer_pointer * (runtime->frame_bits / 8);
    remaining_frames = runtime->buffer_size - s->pcm_buffer_pointer;
    frame_step = s->data_block_quadlets - channels;

    for (i = 0; i < frames; ++i) {
        for (c = 0; c < channels; ++c) {
            *buffer = cpu_to_be32((*src << 8) | 0x40000000);
            src++;
            buffer++;
        }
        buffer += frame_step;
        if (--remaining_frames == 0)
            src = (void *)runtime->dma_area;
    }
}

static void amdtp_fill_pcm_silence(struct amdtp_out_stream *s,
                   __be32 *buffer, unsigned int frames)
{
    unsigned int i, c;

    for (i = 0; i < frames; ++i) {
        for (c = 0; c < s->pcm_channels; ++c)
            buffer[c] = cpu_to_be32(0x40000000);
        buffer += s->data_block_quadlets;
    }
}

static void amdtp_fill_midi(struct amdtp_out_stream *s,
                __be32 *buffer, unsigned int frames)
{
    unsigned int i;

    for (i = 0; i < frames; ++i)
        buffer[s->pcm_channels + i * s->data_block_quadlets] =
                        cpu_to_be32(0x80000000);
}

static void queue_out_packet(struct amdtp_out_stream *s, unsigned int cycle)
{
    __be32 *buffer;
    unsigned int index, data_blocks, syt, ptr;
    struct snd_pcm_substream *pcm;
    struct fw_iso_packet packet;
    int err;

    if (s->packet_index < 0)
        return;
    index = s->packet_index;

    data_blocks = calculate_data_blocks(s);
    syt = calculate_syt(s, cycle);

    buffer = s->buffer.packets[index].buffer;
    buffer[0] = cpu_to_be32(ACCESS_ONCE(s->source_node_id_field) |
                (s->data_block_quadlets << 16) |
                s->data_block_counter);
    buffer[1] = cpu_to_be32(CIP_EOH | CIP_FMT_AM | AMDTP_FDF_AM824 |
                (s->sfc << AMDTP_FDF_SFC_SHIFT) | syt);
    buffer += 2;

    pcm = ACCESS_ONCE(s->pcm);
    if (pcm)
        s->transfer_samples(s, pcm, buffer, data_blocks);
    else
        amdtp_fill_pcm_silence(s, buffer, data_blocks);
    if (s->midi_ports)
        amdtp_fill_midi(s, buffer, data_blocks);

    s->data_block_counter = (s->data_block_counter + data_blocks) & 0xff;

    packet.payload_length = 8 + data_blocks * 4 * s->data_block_quadlets;
    packet.interrupt = IS_ALIGNED(index + 1, INTERRUPT_INTERVAL);
    packet.skip = 0;
    packet.tag = TAG_CIP;
    packet.sy = 0;
    packet.header_length = 0;

    err = fw_iso_context_queue(s->context, &packet, &s->buffer.iso_buffer,
                   s->buffer.packets[index].offset);
    if (err < 0) {
        dev_err(&s->unit->device, "queueing error: %d\n", err);
        s->packet_index = -1;
        amdtp_out_stream_pcm_abort(s);
        return;
    }

    if (++index >= QUEUE_LENGTH)
        index = 0;
    s->packet_index = index;

    if (pcm) {
        ptr = s->pcm_buffer_pointer + data_blocks;
        if (ptr >= pcm->runtime->buffer_size)
            ptr -= pcm->runtime->buffer_size;
        ACCESS_ONCE(s->pcm_buffer_pointer) = ptr;

        s->pcm_period_pointer += data_blocks;
        if (s->pcm_period_pointer >= pcm->runtime->period_size) {
            s->pcm_period_pointer -= pcm->runtime->period_size;
            s->pointer_flush = false;
            tasklet_hi_schedule(&s->period_tasklet);
        }
    }
}

static void pcm_period_tasklet(unsigned long data)
{
    struct amdtp_out_stream *s = (void *)data;
    struct snd_pcm_substream *pcm = ACCESS_ONCE(s->pcm);

    if (pcm)
        snd_pcm_period_elapsed(pcm);
}

static void out_packet_callback(struct fw_iso_context *context, u32 cycle,
                size_t header_length, void *header, void *data)
{
    struct amdtp_out_stream *s = data;
    unsigned int i, packets = header_length / 4;

    /*
     * Compute the cycle of the last queued packet.
     * (We need only the four lowest bits for the SYT, so we can ignore
     * that bits 0-11 must wrap around at 3072.)
     */
    cycle += QUEUE_LENGTH - packets;

    for (i = 0; i < packets; ++i)
        queue_out_packet(s, ++cycle);
    fw_iso_context_queue_flush(s->context);
}

static int queue_initial_skip_packets(struct amdtp_out_stream *s)
{
    struct fw_iso_packet skip_packet = {
        .skip = 1,
    };
    unsigned int i;
    int err;

    for (i = 0; i < QUEUE_LENGTH; ++i) {
        skip_packet.interrupt = IS_ALIGNED(s->packet_index + 1,
                           INTERRUPT_INTERVAL);
        err = fw_iso_context_queue(s->context, &skip_packet, NULL, 0);
        if (err < 0)
            return err;
        if (++s->packet_index >= QUEUE_LENGTH)
            s->packet_index = 0;
    }

    return 0;
}

int amdtp_out_stream_start(struct amdtp_out_stream *s, int channel, int speed)
{
    static const struct {
        unsigned int data_block;
        unsigned int syt_offset;
    } initial_state[] = {
        [CIP_SFC_32000]  = {  4, 3072 },
        [CIP_SFC_48000]  = {  6, 1024 },
        [CIP_SFC_96000]  = { 12, 1024 },
        [CIP_SFC_192000] = { 24, 1024 },
        [CIP_SFC_44100]  = {  0,   67 },
        [CIP_SFC_88200]  = {  0,   67 },
        [CIP_SFC_176400] = {  0,   67 },
    };
    int err;

    mutex_lock(&s->mutex);

    if (WARN_ON(!IS_ERR(s->context) ||
            (!s->pcm_channels && !s->midi_ports))) {
        err = -EBADFD;
        goto err_unlock;
    }

    s->data_block_state = initial_state[s->sfc].data_block;
    s->syt_offset_state = initial_state[s->sfc].syt_offset;
    s->last_syt_offset = TICKS_PER_CYCLE;

    err = iso_packets_buffer_init(&s->buffer, s->unit, QUEUE_LENGTH,
                      amdtp_out_stream_get_max_payload(s),
                      DMA_TO_DEVICE);
    if (err < 0)
        goto err_unlock;

    s->context = fw_iso_context_create(fw_parent_device(s->unit)->card,
                       FW_ISO_CONTEXT_TRANSMIT,
                       channel, speed, 0,
                       out_packet_callback, s);
    if (IS_ERR(s->context)) {
        err = PTR_ERR(s->context);
        if (err == -EBUSY)
            dev_err(&s->unit->device,
                "no free output stream on this controller\n");
        goto err_buffer;
    }

    amdtp_out_stream_update(s);

    s->packet_index = 0;
    s->data_block_counter = 0;
    err = queue_initial_skip_packets(s);
    if (err < 0)
        goto err_context;

    err = fw_iso_context_start(s->context, -1, 0, 0);
    if (err < 0)
        goto err_context;

    mutex_unlock(&s->mutex);

    return 0;

err_context:
    fw_iso_context_destroy(s->context);
    s->context = ERR_PTR(-1);
err_buffer:
    iso_packets_buffer_destroy(&s->buffer, s->unit);
err_unlock:
    mutex_unlock(&s->mutex);

    return err;
}
EXPORT_SYMBOL(amdtp_out_stream_start);

unsigned long amdtp_out_stream_pcm_pointer(struct amdtp_out_stream *s)
{
    /* this optimization is allowed to be racy */
    if (s->pointer_flush)
        fw_iso_context_flush_completions(s->context);
    else
        s->pointer_flush = true;

    return ACCESS_ONCE(s->pcm_buffer_pointer);
}
EXPORT_SYMBOL(amdtp_out_stream_pcm_pointer);

void amdtp_out_stream_update(struct amdtp_out_stream *s)
{
    ACCESS_ONCE(s->source_node_id_field) =
        (fw_parent_device(s->unit)->card->node_id & 0x3f) << 24;
}
EXPORT_SYMBOL(amdtp_out_stream_update);

void amdtp_out_stream_stop(struct amdtp_out_stream *s)
{
    mutex_lock(&s->mutex);

    if (IS_ERR(s->context)) {
        mutex_unlock(&s->mutex);
        return;
    }

    tasklet_kill(&s->period_tasklet);
    fw_iso_context_stop(s->context);
    fw_iso_context_destroy(s->context);
    s->context = ERR_PTR(-1);
    iso_packets_buffer_destroy(&s->buffer, s->unit);

    mutex_unlock(&s->mutex);
}
EXPORT_SYMBOL(amdtp_out_stream_stop);

void amdtp_out_stream_pcm_abort(struct amdtp_out_stream *s)
{
    struct snd_pcm_substream *pcm;

    pcm = ACCESS_ONCE(s->pcm);
    if (pcm) {
        snd_pcm_stream_lock_irq(pcm);
        if (snd_pcm_running(pcm))
            snd_pcm_stop(pcm, SNDRV_PCM_STATE_XRUN);
        snd_pcm_stream_unlock_irq(pcm);
    }
}
EXPORT_SYMBOL(amdtp_out_stream_pcm_abort);