398 lines
11 KiB
C
398 lines
11 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* AM824 format in Audio and Music Data Transmission Protocol (IEC 61883-6)
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*
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* Copyright (c) Clemens Ladisch <clemens@ladisch.de>
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* Copyright (c) 2015 Takashi Sakamoto <o-takashi@sakamocchi.jp>
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*/
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#include <linux/slab.h>
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#include "amdtp-am824.h"
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#define CIP_FMT_AM 0x10
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/* "Clock-based rate control mode" is just supported. */
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#define AMDTP_FDF_AM824 0x00
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/*
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* Nominally 3125 bytes/second, but the MIDI port's clock might be
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* 1% too slow, and the bus clock 100 ppm too fast.
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*/
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#define MIDI_BYTES_PER_SECOND 3093
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/*
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* Several devices look only at the first eight data blocks.
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* In any case, this is more than enough for the MIDI data rate.
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*/
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#define MAX_MIDI_RX_BLOCKS 8
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struct amdtp_am824 {
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struct snd_rawmidi_substream *midi[AM824_MAX_CHANNELS_FOR_MIDI * 8];
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int midi_fifo_limit;
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int midi_fifo_used[AM824_MAX_CHANNELS_FOR_MIDI * 8];
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unsigned int pcm_channels;
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unsigned int midi_ports;
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u8 pcm_positions[AM824_MAX_CHANNELS_FOR_PCM];
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u8 midi_position;
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unsigned int frame_multiplier;
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};
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/**
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* amdtp_am824_set_parameters - set stream parameters
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* @s: the AMDTP stream to configure
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* @rate: the sample rate
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* @pcm_channels: the number of PCM samples in each data block, to be encoded
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* as AM824 multi-bit linear audio
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* @midi_ports: the number of MIDI ports (i.e., MPX-MIDI Data Channels)
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* @double_pcm_frames: one data block transfers two PCM frames
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*
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* The parameters 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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*/
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int amdtp_am824_set_parameters(struct amdtp_stream *s, unsigned int rate,
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unsigned int pcm_channels,
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unsigned int midi_ports,
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bool double_pcm_frames)
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{
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struct amdtp_am824 *p = s->protocol;
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unsigned int midi_channels;
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unsigned int i;
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int err;
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if (amdtp_stream_running(s))
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return -EINVAL;
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if (pcm_channels > AM824_MAX_CHANNELS_FOR_PCM)
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return -EINVAL;
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midi_channels = DIV_ROUND_UP(midi_ports, 8);
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if (midi_channels > AM824_MAX_CHANNELS_FOR_MIDI)
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return -EINVAL;
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if (WARN_ON(amdtp_stream_running(s)) ||
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WARN_ON(pcm_channels > AM824_MAX_CHANNELS_FOR_PCM) ||
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WARN_ON(midi_channels > AM824_MAX_CHANNELS_FOR_MIDI))
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return -EINVAL;
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err = amdtp_stream_set_parameters(s, rate,
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pcm_channels + midi_channels);
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if (err < 0)
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return err;
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s->fdf = AMDTP_FDF_AM824 | s->sfc;
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p->pcm_channels = pcm_channels;
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p->midi_ports = midi_ports;
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/*
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* In IEC 61883-6, one data block represents one event. In ALSA, one
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* event equals to one PCM frame. But Dice has a quirk at higher
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* sampling rate to transfer two PCM frames in one data block.
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*/
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if (double_pcm_frames)
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p->frame_multiplier = 2;
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else
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p->frame_multiplier = 1;
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/* init the position map for PCM and MIDI channels */
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for (i = 0; i < pcm_channels; i++)
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p->pcm_positions[i] = i;
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p->midi_position = p->pcm_channels;
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/*
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* We do not know the actual MIDI FIFO size of most devices. Just
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* assume two bytes, i.e., one byte can be received over the bus while
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* the previous one is transmitted over MIDI.
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* (The value here is adjusted for midi_ratelimit_per_packet().)
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*/
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p->midi_fifo_limit = rate - MIDI_BYTES_PER_SECOND * s->syt_interval + 1;
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return 0;
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}
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EXPORT_SYMBOL_GPL(amdtp_am824_set_parameters);
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/**
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* amdtp_am824_set_pcm_position - set an index of data channel for a channel
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* of PCM frame
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* @s: the AMDTP stream
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* @index: the index of data channel in an data block
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* @position: the channel of PCM frame
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*/
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void amdtp_am824_set_pcm_position(struct amdtp_stream *s, unsigned int index,
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unsigned int position)
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{
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struct amdtp_am824 *p = s->protocol;
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if (index < p->pcm_channels)
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p->pcm_positions[index] = position;
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}
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EXPORT_SYMBOL_GPL(amdtp_am824_set_pcm_position);
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/**
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* amdtp_am824_set_midi_position - set a index of data channel for MIDI
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* conformant data channel
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* @s: the AMDTP stream
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* @position: the index of data channel in an data block
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*/
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void amdtp_am824_set_midi_position(struct amdtp_stream *s,
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unsigned int position)
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{
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struct amdtp_am824 *p = s->protocol;
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p->midi_position = position;
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}
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EXPORT_SYMBOL_GPL(amdtp_am824_set_midi_position);
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static void write_pcm_s32(struct amdtp_stream *s,
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struct snd_pcm_substream *pcm,
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__be32 *buffer, unsigned int frames)
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{
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struct amdtp_am824 *p = s->protocol;
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struct snd_pcm_runtime *runtime = pcm->runtime;
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unsigned int channels, remaining_frames, i, c;
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const u32 *src;
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channels = p->pcm_channels;
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src = (void *)runtime->dma_area +
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frames_to_bytes(runtime, s->pcm_buffer_pointer);
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remaining_frames = runtime->buffer_size - s->pcm_buffer_pointer;
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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[p->pcm_positions[c]] =
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cpu_to_be32((*src >> 8) | 0x40000000);
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src++;
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}
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buffer += s->data_block_quadlets;
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if (--remaining_frames == 0)
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src = (void *)runtime->dma_area;
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}
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}
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static void read_pcm_s32(struct amdtp_stream *s,
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struct snd_pcm_substream *pcm,
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__be32 *buffer, unsigned int frames)
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{
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struct amdtp_am824 *p = s->protocol;
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struct snd_pcm_runtime *runtime = pcm->runtime;
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unsigned int channels, remaining_frames, i, c;
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u32 *dst;
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channels = p->pcm_channels;
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dst = (void *)runtime->dma_area +
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frames_to_bytes(runtime, s->pcm_buffer_pointer);
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remaining_frames = runtime->buffer_size - s->pcm_buffer_pointer;
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for (i = 0; i < frames; ++i) {
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for (c = 0; c < channels; ++c) {
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*dst = be32_to_cpu(buffer[p->pcm_positions[c]]) << 8;
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dst++;
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}
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buffer += s->data_block_quadlets;
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if (--remaining_frames == 0)
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dst = (void *)runtime->dma_area;
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}
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}
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static void write_pcm_silence(struct amdtp_stream *s,
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__be32 *buffer, unsigned int frames)
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{
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struct amdtp_am824 *p = s->protocol;
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unsigned int i, c, channels = p->pcm_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[p->pcm_positions[c]] = cpu_to_be32(0x40000000);
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buffer += s->data_block_quadlets;
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}
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}
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/**
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* amdtp_am824_add_pcm_hw_constraints - add hw constraints for PCM substream
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* @s: the AMDTP stream for AM824 data block, must be initialized.
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* @runtime: the PCM substream runtime
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*
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*/
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int amdtp_am824_add_pcm_hw_constraints(struct amdtp_stream *s,
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struct snd_pcm_runtime *runtime)
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{
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int err;
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err = amdtp_stream_add_pcm_hw_constraints(s, runtime);
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if (err < 0)
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return err;
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/* AM824 in IEC 61883-6 can deliver 24bit data. */
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return snd_pcm_hw_constraint_msbits(runtime, 0, 32, 24);
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}
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EXPORT_SYMBOL_GPL(amdtp_am824_add_pcm_hw_constraints);
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/**
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* amdtp_am824_midi_trigger - start/stop playback/capture with a MIDI device
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* @s: the AMDTP stream
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* @port: index of MIDI port
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* @midi: the MIDI device to be started, or %NULL to stop the current device
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*
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* Call this function on a running isochronous stream to enable the actual
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* transmission of MIDI data. This function should be called from the MIDI
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* device's .trigger callback.
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*/
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void amdtp_am824_midi_trigger(struct amdtp_stream *s, unsigned int port,
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struct snd_rawmidi_substream *midi)
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{
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struct amdtp_am824 *p = s->protocol;
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if (port < p->midi_ports)
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WRITE_ONCE(p->midi[port], midi);
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}
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EXPORT_SYMBOL_GPL(amdtp_am824_midi_trigger);
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/*
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* To avoid sending MIDI bytes at too high a rate, assume that the receiving
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* device has a FIFO, and track how much it is filled. This values increases
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* by one whenever we send one byte in a packet, but the FIFO empties at
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* a constant rate independent of our packet rate. One packet has syt_interval
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* samples, so the number of bytes that empty out of the FIFO, per packet(!),
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* is MIDI_BYTES_PER_SECOND * syt_interval / sample_rate. To avoid storing
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* fractional values, the values in midi_fifo_used[] are measured in bytes
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* multiplied by the sample rate.
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*/
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static bool midi_ratelimit_per_packet(struct amdtp_stream *s, unsigned int port)
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{
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struct amdtp_am824 *p = s->protocol;
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int used;
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used = p->midi_fifo_used[port];
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if (used == 0) /* common shortcut */
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return true;
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used -= MIDI_BYTES_PER_SECOND * s->syt_interval;
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used = max(used, 0);
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p->midi_fifo_used[port] = used;
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return used < p->midi_fifo_limit;
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}
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static void midi_rate_use_one_byte(struct amdtp_stream *s, unsigned int port)
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{
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struct amdtp_am824 *p = s->protocol;
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p->midi_fifo_used[port] += amdtp_rate_table[s->sfc];
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}
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static void write_midi_messages(struct amdtp_stream *s, __be32 *buffer,
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unsigned int frames)
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{
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struct amdtp_am824 *p = s->protocol;
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unsigned int f, port;
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u8 *b;
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for (f = 0; f < frames; f++) {
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b = (u8 *)&buffer[p->midi_position];
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port = (s->data_block_counter + f) % 8;
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if (f < MAX_MIDI_RX_BLOCKS &&
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midi_ratelimit_per_packet(s, port) &&
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p->midi[port] != NULL &&
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snd_rawmidi_transmit(p->midi[port], &b[1], 1) == 1) {
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midi_rate_use_one_byte(s, port);
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b[0] = 0x81;
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} else {
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b[0] = 0x80;
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b[1] = 0;
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}
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b[2] = 0;
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b[3] = 0;
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buffer += s->data_block_quadlets;
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}
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}
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static void read_midi_messages(struct amdtp_stream *s,
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__be32 *buffer, unsigned int frames)
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{
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struct amdtp_am824 *p = s->protocol;
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unsigned int f, port;
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int len;
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u8 *b;
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for (f = 0; f < frames; f++) {
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port = (8 - s->tx_first_dbc + s->data_block_counter + f) % 8;
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b = (u8 *)&buffer[p->midi_position];
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len = b[0] - 0x80;
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if ((1 <= len) && (len <= 3) && (p->midi[port]))
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snd_rawmidi_receive(p->midi[port], b + 1, len);
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buffer += s->data_block_quadlets;
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}
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}
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static unsigned int process_rx_data_blocks(struct amdtp_stream *s, __be32 *buffer,
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unsigned int data_blocks, unsigned int *syt)
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{
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struct amdtp_am824 *p = s->protocol;
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struct snd_pcm_substream *pcm = READ_ONCE(s->pcm);
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unsigned int pcm_frames;
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if (pcm) {
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write_pcm_s32(s, pcm, buffer, data_blocks);
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pcm_frames = data_blocks * p->frame_multiplier;
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} else {
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write_pcm_silence(s, buffer, data_blocks);
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pcm_frames = 0;
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}
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if (p->midi_ports)
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write_midi_messages(s, buffer, data_blocks);
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return pcm_frames;
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}
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static unsigned int process_tx_data_blocks(struct amdtp_stream *s, __be32 *buffer,
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unsigned int data_blocks, unsigned int *syt)
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{
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struct amdtp_am824 *p = s->protocol;
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struct snd_pcm_substream *pcm = READ_ONCE(s->pcm);
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unsigned int pcm_frames;
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if (pcm) {
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read_pcm_s32(s, pcm, buffer, data_blocks);
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pcm_frames = data_blocks * p->frame_multiplier;
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} else {
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pcm_frames = 0;
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}
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if (p->midi_ports)
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read_midi_messages(s, buffer, data_blocks);
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return pcm_frames;
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}
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/**
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* amdtp_am824_init - initialize an AMDTP stream structure to handle AM824
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* data block
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* @s: the AMDTP stream to initialize
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* @unit: the target of the stream
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* @dir: the direction of stream
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* @flags: the packet transmission method to use
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*/
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int amdtp_am824_init(struct amdtp_stream *s, struct fw_unit *unit,
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enum amdtp_stream_direction dir, enum cip_flags flags)
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{
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amdtp_stream_process_data_blocks_t process_data_blocks;
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if (dir == AMDTP_IN_STREAM)
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process_data_blocks = process_tx_data_blocks;
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else
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process_data_blocks = process_rx_data_blocks;
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return amdtp_stream_init(s, unit, dir, flags, CIP_FMT_AM,
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process_data_blocks,
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sizeof(struct amdtp_am824));
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}
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EXPORT_SYMBOL_GPL(amdtp_am824_init);
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