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* Audio and Music Data Transmission Protocol (IEC 61883-6) streams
3
* with Common Isochronous Packet (IEC 61883-1) headers
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* Copyright (c) Clemens Ladisch <clemens@ladisch.de>
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* Licensed under the terms of the GNU General Public License, version 2.
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#include <linux/device.h>
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#include <linux/err.h>
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#include <linux/firewire.h>
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#include <linux/module.h>
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#include <linux/slab.h>
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#include <sound/pcm.h>
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#define TICKS_PER_CYCLE 3072
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#define CYCLES_PER_SECOND 8000
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#define TICKS_PER_SECOND (TICKS_PER_CYCLE * CYCLES_PER_SECOND)
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#define TRANSFER_DELAY_TICKS 0x2e00 /* 479.17 µs */
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#define CIP_EOH (1u << 31)
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#define CIP_FMT_AM (0x10 << 24)
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#define AMDTP_FDF_AM824 (0 << 19)
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#define AMDTP_FDF_SFC_SHIFT 16
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/* TODO: make these configurable */
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#define INTERRUPT_INTERVAL 16
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#define QUEUE_LENGTH 48
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* amdtp_out_stream_init - initialize an AMDTP output stream structure
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* @s: the AMDTP output stream to initialize
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* @unit: the target of the stream
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* @flags: the packet transmission method to use
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int amdtp_out_stream_init(struct amdtp_out_stream *s, struct fw_unit *unit,
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enum cip_out_flags flags)
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if (flags != CIP_NONBLOCKING)
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s->unit = fw_unit_get(unit);
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s->context = ERR_PTR(-1);
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mutex_init(&s->mutex);
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EXPORT_SYMBOL(amdtp_out_stream_init);
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* amdtp_out_stream_destroy - free stream resources
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* @s: the AMDTP output stream to destroy
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void amdtp_out_stream_destroy(struct amdtp_out_stream *s)
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WARN_ON(!IS_ERR(s->context));
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mutex_destroy(&s->mutex);
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EXPORT_SYMBOL(amdtp_out_stream_destroy);
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* amdtp_out_stream_set_rate - set the sample rate
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* @s: the AMDTP output stream to configure
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* @rate: the sample rate
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* The sample rate must be set before the stream is started, and must not be
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* changed while the stream is running.
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void amdtp_out_stream_set_rate(struct amdtp_out_stream *s, unsigned int rate)
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unsigned int syt_interval;
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[CIP_SFC_32000] = { 32000, 8, },
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[CIP_SFC_44100] = { 44100, 8, },
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[CIP_SFC_48000] = { 48000, 8, },
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[CIP_SFC_88200] = { 88200, 16, },
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[CIP_SFC_96000] = { 96000, 16, },
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[CIP_SFC_176400] = { 176400, 32, },
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[CIP_SFC_192000] = { 192000, 32, },
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if (WARN_ON(!IS_ERR(s->context)))
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for (sfc = 0; sfc < ARRAY_SIZE(rate_info); ++sfc)
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if (rate_info[sfc].rate == rate) {
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s->syt_interval = rate_info[sfc].syt_interval;
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EXPORT_SYMBOL(amdtp_out_stream_set_rate);
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* amdtp_out_stream_get_max_payload - get the stream's packet size
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* @s: the AMDTP output stream
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* This function must not be called before the stream has been configured
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* with amdtp_out_stream_set_hw_params(), amdtp_out_stream_set_pcm(), and
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* amdtp_out_stream_set_midi().
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unsigned int amdtp_out_stream_get_max_payload(struct amdtp_out_stream *s)
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static const unsigned int max_data_blocks[] = {
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[CIP_SFC_88200] = 12,
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[CIP_SFC_96000] = 12,
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[CIP_SFC_176400] = 23,
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[CIP_SFC_192000] = 24,
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s->data_block_quadlets = s->pcm_channels;
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s->data_block_quadlets += DIV_ROUND_UP(s->midi_ports, 8);
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return 8 + max_data_blocks[s->sfc] * 4 * s->data_block_quadlets;
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EXPORT_SYMBOL(amdtp_out_stream_get_max_payload);
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static void amdtp_write_s16(struct amdtp_out_stream *s,
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struct snd_pcm_substream *pcm,
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__be32 *buffer, unsigned int frames);
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static void amdtp_write_s32(struct amdtp_out_stream *s,
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struct snd_pcm_substream *pcm,
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__be32 *buffer, unsigned int frames);
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* amdtp_out_stream_set_pcm_format - set the PCM format
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* @s: the AMDTP output stream to configure
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* @format: the format of the ALSA PCM device
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* The sample format must be set before the stream is started, and must not be
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* changed while the stream is running.
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void amdtp_out_stream_set_pcm_format(struct amdtp_out_stream *s,
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snd_pcm_format_t format)
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if (WARN_ON(!IS_ERR(s->context)))
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case SNDRV_PCM_FORMAT_S16:
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s->transfer_samples = amdtp_write_s16;
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case SNDRV_PCM_FORMAT_S32:
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s->transfer_samples = amdtp_write_s32;
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EXPORT_SYMBOL(amdtp_out_stream_set_pcm_format);
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static unsigned int calculate_data_blocks(struct amdtp_out_stream *s)
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unsigned int phase, data_blocks;
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if (!cip_sfc_is_base_44100(s->sfc)) {
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/* Sample_rate / 8000 is an integer, and precomputed. */
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data_blocks = s->data_block_state;
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phase = s->data_block_state;
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* This calculates the number of data blocks per packet so that
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* 1) the overall rate is correct and exactly synchronized to
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* 2) packets with a rounded-up number of blocks occur as early
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* as possible in the sequence (to prevent underruns of the
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if (s->sfc == CIP_SFC_44100)
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/* 6 6 5 6 5 6 5 ... */
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data_blocks = 5 + ((phase & 1) ^
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(phase == 0 || phase >= 40));
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/* 12 11 11 11 11 ... or 23 22 22 22 22 ... */
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data_blocks = 11 * (s->sfc >> 1) + (phase == 0);
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if (++phase >= (80 >> (s->sfc >> 1)))
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s->data_block_state = phase;
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static unsigned int calculate_syt(struct amdtp_out_stream *s,
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unsigned int syt_offset, phase, index, syt;
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if (s->last_syt_offset < TICKS_PER_CYCLE) {
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if (!cip_sfc_is_base_44100(s->sfc))
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syt_offset = s->last_syt_offset + s->syt_offset_state;
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* The time, in ticks, of the n'th SYT_INTERVAL sample is:
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* n * SYT_INTERVAL * 24576000 / sample_rate
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* Modulo TICKS_PER_CYCLE, the difference between successive
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* elements is about 1386.23. Rounding the results of this
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* formula to the SYT precision results in a sequence of
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* differences that begins with:
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* 1386 1386 1387 1386 1386 1386 1387 1386 1386 1386 1387 ...
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* This code generates _exactly_ the same sequence.
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phase = s->syt_offset_state;
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syt_offset = s->last_syt_offset;
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syt_offset += 1386 + ((index && !(index & 3)) ||
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s->syt_offset_state = phase;
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syt_offset = s->last_syt_offset - TICKS_PER_CYCLE;
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s->last_syt_offset = syt_offset;
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if (syt_offset < TICKS_PER_CYCLE) {
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syt_offset += TRANSFER_DELAY_TICKS - TICKS_PER_CYCLE;
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syt = (cycle + syt_offset / TICKS_PER_CYCLE) << 12;
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syt += syt_offset % TICKS_PER_CYCLE;
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return 0xffff; /* no info */
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static void amdtp_write_s32(struct amdtp_out_stream *s,
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struct snd_pcm_substream *pcm,
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__be32 *buffer, unsigned int frames)
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struct snd_pcm_runtime *runtime = pcm->runtime;
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unsigned int channels, remaining_frames, frame_step, i, c;
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channels = s->pcm_channels;
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src = (void *)runtime->dma_area +
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s->pcm_buffer_pointer * (runtime->frame_bits / 8);
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remaining_frames = runtime->buffer_size - s->pcm_buffer_pointer;
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frame_step = s->data_block_quadlets - channels;
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for (i = 0; i < frames; ++i) {
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for (c = 0; c < channels; ++c) {
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*buffer = cpu_to_be32((*src >> 8) | 0x40000000);
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buffer += frame_step;
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if (--remaining_frames == 0)
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src = (void *)runtime->dma_area;
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static void amdtp_write_s16(struct amdtp_out_stream *s,
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struct snd_pcm_substream *pcm,
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__be32 *buffer, unsigned int frames)
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struct snd_pcm_runtime *runtime = pcm->runtime;
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unsigned int channels, remaining_frames, frame_step, i, c;
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channels = s->pcm_channels;
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src = (void *)runtime->dma_area +
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s->pcm_buffer_pointer * (runtime->frame_bits / 8);
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remaining_frames = runtime->buffer_size - s->pcm_buffer_pointer;
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frame_step = s->data_block_quadlets - channels;
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for (i = 0; i < frames; ++i) {
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for (c = 0; c < channels; ++c) {
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*buffer = cpu_to_be32((*src << 8) | 0x40000000);
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buffer += frame_step;
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if (--remaining_frames == 0)
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src = (void *)runtime->dma_area;
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static void amdtp_fill_pcm_silence(struct amdtp_out_stream *s,
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__be32 *buffer, unsigned int frames)
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for (i = 0; i < frames; ++i) {
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for (c = 0; c < s->pcm_channels; ++c)
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buffer[c] = cpu_to_be32(0x40000000);
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buffer += s->data_block_quadlets;
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static void amdtp_fill_midi(struct amdtp_out_stream *s,
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__be32 *buffer, unsigned int frames)
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for (i = 0; i < frames; ++i)
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buffer[s->pcm_channels + i * s->data_block_quadlets] =
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cpu_to_be32(0x80000000);
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static void queue_out_packet(struct amdtp_out_stream *s, unsigned int cycle)
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unsigned int index, data_blocks, syt, ptr;
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struct snd_pcm_substream *pcm;
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struct fw_iso_packet packet;
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if (s->packet_index < 0)
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index = s->packet_index;
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data_blocks = calculate_data_blocks(s);
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syt = calculate_syt(s, cycle);
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buffer = s->buffer.packets[index].buffer;
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buffer[0] = cpu_to_be32(ACCESS_ONCE(s->source_node_id_field) |
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(s->data_block_quadlets << 16) |
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s->data_block_counter);
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buffer[1] = cpu_to_be32(CIP_EOH | CIP_FMT_AM | AMDTP_FDF_AM824 |
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(s->sfc << AMDTP_FDF_SFC_SHIFT) | syt);
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pcm = ACCESS_ONCE(s->pcm);
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s->transfer_samples(s, pcm, buffer, data_blocks);
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amdtp_fill_pcm_silence(s, buffer, data_blocks);
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amdtp_fill_midi(s, buffer, data_blocks);
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s->data_block_counter = (s->data_block_counter + data_blocks) & 0xff;
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packet.payload_length = 8 + data_blocks * 4 * s->data_block_quadlets;
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packet.interrupt = IS_ALIGNED(index + 1, INTERRUPT_INTERVAL);
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packet.tag = TAG_CIP;
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packet.header_length = 0;
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err = fw_iso_context_queue(s->context, &packet, &s->buffer.iso_buffer,
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s->buffer.packets[index].offset);
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dev_err(&s->unit->device, "queueing error: %d\n", err);
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s->packet_index = -1;
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amdtp_out_stream_pcm_abort(s);
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if (++index >= QUEUE_LENGTH)
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s->packet_index = index;
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ptr = s->pcm_buffer_pointer + data_blocks;
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if (ptr >= pcm->runtime->buffer_size)
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ptr -= pcm->runtime->buffer_size;
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ACCESS_ONCE(s->pcm_buffer_pointer) = ptr;
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s->pcm_period_pointer += data_blocks;
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if (s->pcm_period_pointer >= pcm->runtime->period_size) {
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s->pcm_period_pointer -= pcm->runtime->period_size;
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snd_pcm_period_elapsed(pcm);
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static void out_packet_callback(struct fw_iso_context *context, u32 cycle,
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size_t header_length, void *header, void *data)
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struct amdtp_out_stream *s = data;
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unsigned int i, packets = header_length / 4;
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* Compute the cycle of the last queued packet.
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* (We need only the four lowest bits for the SYT, so we can ignore
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* that bits 0-11 must wrap around at 3072.)
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cycle += QUEUE_LENGTH - packets;
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for (i = 0; i < packets; ++i)
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queue_out_packet(s, ++cycle);
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fw_iso_context_queue_flush(s->context);
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static int queue_initial_skip_packets(struct amdtp_out_stream *s)
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struct fw_iso_packet skip_packet = {
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for (i = 0; i < QUEUE_LENGTH; ++i) {
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skip_packet.interrupt = IS_ALIGNED(s->packet_index + 1,
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err = fw_iso_context_queue(s->context, &skip_packet, NULL, 0);
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if (++s->packet_index >= QUEUE_LENGTH)
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* amdtp_out_stream_start - start sending packets
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* @s: the AMDTP output stream to start
426
* @channel: the isochronous channel on the bus
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* @speed: firewire speed code
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* The stream cannot be started until it has been configured with
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* amdtp_out_stream_set_hw_params(), amdtp_out_stream_set_pcm(), and
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* amdtp_out_stream_set_midi(); and it must be started before any
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* PCM or MIDI device can be started.
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int amdtp_out_stream_start(struct amdtp_out_stream *s, int channel, int speed)
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static const struct {
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unsigned int data_block;
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unsigned int syt_offset;
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} initial_state[] = {
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[CIP_SFC_32000] = { 4, 3072 },
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[CIP_SFC_48000] = { 6, 1024 },
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[CIP_SFC_96000] = { 12, 1024 },
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[CIP_SFC_192000] = { 24, 1024 },
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[CIP_SFC_44100] = { 0, 67 },
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[CIP_SFC_88200] = { 0, 67 },
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[CIP_SFC_176400] = { 0, 67 },
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mutex_lock(&s->mutex);
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if (WARN_ON(!IS_ERR(s->context) ||
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(!s->pcm_channels && !s->midi_ports))) {
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s->data_block_state = initial_state[s->sfc].data_block;
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s->syt_offset_state = initial_state[s->sfc].syt_offset;
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s->last_syt_offset = TICKS_PER_CYCLE;
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err = iso_packets_buffer_init(&s->buffer, s->unit, QUEUE_LENGTH,
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amdtp_out_stream_get_max_payload(s),
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s->context = fw_iso_context_create(fw_parent_device(s->unit)->card,
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FW_ISO_CONTEXT_TRANSMIT,
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out_packet_callback, s);
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if (IS_ERR(s->context)) {
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err = PTR_ERR(s->context);
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dev_err(&s->unit->device,
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"no free output stream on this controller\n");
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amdtp_out_stream_update(s);
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s->data_block_counter = 0;
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err = queue_initial_skip_packets(s);
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err = fw_iso_context_start(s->context, -1, 0, 0);
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mutex_unlock(&s->mutex);
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fw_iso_context_destroy(s->context);
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s->context = ERR_PTR(-1);
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iso_packets_buffer_destroy(&s->buffer, s->unit);
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mutex_unlock(&s->mutex);
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EXPORT_SYMBOL(amdtp_out_stream_start);
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* amdtp_out_stream_update - update the stream after a bus reset
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* @s: the AMDTP output stream
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void amdtp_out_stream_update(struct amdtp_out_stream *s)
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ACCESS_ONCE(s->source_node_id_field) =
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(fw_parent_device(s->unit)->card->node_id & 0x3f) << 24;
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EXPORT_SYMBOL(amdtp_out_stream_update);
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* amdtp_out_stream_stop - stop sending packets
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* @s: the AMDTP output stream to stop
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* All PCM and MIDI devices of the stream must be stopped before the stream
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* itself can be stopped.
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void amdtp_out_stream_stop(struct amdtp_out_stream *s)
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mutex_lock(&s->mutex);
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if (IS_ERR(s->context)) {
531
mutex_unlock(&s->mutex);
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fw_iso_context_stop(s->context);
536
fw_iso_context_destroy(s->context);
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s->context = ERR_PTR(-1);
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iso_packets_buffer_destroy(&s->buffer, s->unit);
540
mutex_unlock(&s->mutex);
542
EXPORT_SYMBOL(amdtp_out_stream_stop);
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* amdtp_out_stream_pcm_abort - abort the running PCM device
546
* @s: the AMDTP stream about to be stopped
548
* If the isochronous stream needs to be stopped asynchronously, call this
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* function first to stop the PCM device.
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void amdtp_out_stream_pcm_abort(struct amdtp_out_stream *s)
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struct snd_pcm_substream *pcm;
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pcm = ACCESS_ONCE(s->pcm);
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snd_pcm_stream_lock_irq(pcm);
558
if (snd_pcm_running(pcm))
559
snd_pcm_stop(pcm, SNDRV_PCM_STATE_XRUN);
560
snd_pcm_stream_unlock_irq(pcm);
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EXPORT_SYMBOL(amdtp_out_stream_pcm_abort);