/*
* AM824 format in Audio and Music Data Transmission Protocol (IEC 61883-6)
*
* Copyright (c) Clemens Ladisch <clemens@ladisch.de>
* Copyright (c) 2015 Takashi Sakamoto <o-takashi@sakamocchi.jp>
*
* Licensed under the terms of the GNU General Public License, version 2.
*/
#include <linux/slab.h>
#include "amdtp-am824.h"
#define CIP_FMT_AM 0x10
/* "Clock-based rate control mode" is just supported. */
#define AMDTP_FDF_AM824 0x00
/*
* Nominally 3125 bytes/second, but the MIDI port's clock might be
* 1% too slow, and the bus clock 100 ppm too fast.
*/
#define MIDI_BYTES_PER_SECOND 3093
/*
* Several devices look only at the first eight data blocks.
* In any case, this is more than enough for the MIDI data rate.
*/
#define MAX_MIDI_RX_BLOCKS 8
struct amdtp_am824 {
struct snd_rawmidi_substream *midi[AM824_MAX_CHANNELS_FOR_MIDI * 8];
int midi_fifo_limit;
int midi_fifo_used[AM824_MAX_CHANNELS_FOR_MIDI * 8];
unsigned int pcm_channels;
unsigned int midi_ports;
u8 pcm_positions[AM824_MAX_CHANNELS_FOR_PCM];
u8 midi_position;
void (*transfer_samples)(struct amdtp_stream *s,
struct snd_pcm_substream *pcm,
__be32 *buffer, unsigned int frames);
unsigned int frame_multiplier;
};
/**
* amdtp_am824_set_parameters - set stream parameters
* @s: the AMDTP stream to configure
* @rate: the sample rate
* @pcm_channels: the number of PCM samples in each data block, to be encoded
* as AM824 multi-bit linear audio
* @midi_ports: the number of MIDI ports (i.e., MPX-MIDI Data Channels)
* @double_pcm_frames: one data block transfers two PCM frames
*
* The parameters must be set before the stream is started, and must not be
* changed while the stream is running.
*/
int amdtp_am824_set_parameters(struct amdtp_stream *s, unsigned int rate,
unsigned int pcm_channels,
unsigned int midi_ports,
bool double_pcm_frames)
{
struct amdtp_am824 *p = s->protocol;
unsigned int midi_channels;
unsigned int i;
int err;
if (amdtp_stream_running(s))
return -EINVAL;
if (pcm_channels > AM824_MAX_CHANNELS_FOR_PCM)
return -EINVAL;
midi_channels = DIV_ROUND_UP(midi_ports, 8);
if (midi_channels > AM824_MAX_CHANNELS_FOR_MIDI)
return -EINVAL;
if (WARN_ON(amdtp_stream_running(s)) ||
WARN_ON(pcm_channels > AM824_MAX_CHANNELS_FOR_PCM) ||
WARN_ON(midi_channels > AM824_MAX_CHANNELS_FOR_MIDI))
return -EINVAL;
err = amdtp_stream_set_parameters(s, rate,
pcm_channels + midi_channels);
if (err < 0)
return err;
s->fdf = AMDTP_FDF_AM824 | s->sfc;
p->pcm_channels = pcm_channels;
p->midi_ports = midi_ports;
/*
* In IEC 61883-6, one data block represents one event. In ALSA, one
* event equals to one PCM frame. But Dice has a quirk at higher
* sampling rate to transfer two PCM frames in one data block.
*/
if (double_pcm_frames)
p->frame_multiplier = 2;
else
p->frame_multiplier = 1;
/* init the position map for PCM and MIDI channels */
for (i = 0; i < pcm_channels; i++)
p->pcm_positions[i] = i;
p->midi_position = p->pcm_channels;
/*
* We do not know the actual MIDI FIFO size of most devices. Just
* assume two bytes, i.e., one byte can be received over the bus while
* the previous one is transmitted over MIDI.
* (The value here is adjusted for midi_ratelimit_per_packet().)
*/
p->midi_fifo_limit = rate - MIDI_BYTES_PER_SECOND * s->syt_interval + 1;
return 0;
}
EXPORT_SYMBOL_GPL(amdtp_am824_set_parameters);
/**
* amdtp_am824_set_pcm_position - set an index of data channel for a channel
* of PCM frame
* @s: the AMDTP stream
* @index: the index of data channel in an data block
* @position: the channel of PCM frame
*/
void amdtp_am824_set_pcm_position(struct amdtp_stream *s, unsigned int index,
unsigned int position)
{
struct amdtp_am824 *p = s->protocol;
if (index < p->pcm_channels)
p->pcm_positions[index] = position;
}
EXPORT_SYMBOL_GPL(amdtp_am824_set_pcm_position);
/**
* amdtp_am824_set_midi_position - set a index of data channel for MIDI
* conformant data channel
* @s: the AMDTP stream
* @position: the index of data channel in an data block
*/
void amdtp_am824_set_midi_position(struct amdtp_stream *s,
unsigned int position)
{
struct amdtp_am824 *p = s->protocol;
p->midi_position = position;
}
EXPORT_SYMBOL_GPL(amdtp_am824_set_midi_position);
static void write_pcm_s32(struct amdtp_stream *s,
struct snd_pcm_substream *pcm,
__be32 *buffer, unsigned int frames)
{
struct amdtp_am824 *p = s->protocol;
struct snd_pcm_runtime *runtime = pcm->runtime;
unsigned int channels, remaining_frames, i, c;
const u32 *src;
channels = p->pcm_channels;
src = (void *)runtime->dma_area +
frames_to_bytes(runtime, s->pcm_buffer_pointer);
remaining_frames = runtime->buffer_size - s->pcm_buffer_pointer;
for (i = 0; i < frames; ++i) {
for (c = 0; c < channels; ++c) {
buffer[p->pcm_positions[c]] =
cpu_to_be32((*src >> 8) | 0x40000000);
src++;
}
buffer += s->data_block_quadlets;
if (--remaining_frames == 0)
src = (void *)runtime->dma_area;
}
}
static void write_pcm_s16(struct amdtp_stream *s,
struct snd_pcm_substream *pcm,
__be32 *buffer, unsigned int frames)
{
struct amdtp_am824 *p = s->protocol;
struct snd_pcm_runtime *runtime = pcm->runtime;
unsigned int channels, remaining_frames, i, c;
const u16 *src;
channels = p->pcm_channels;
src = (void *)runtime->dma_area +
frames_to_bytes(runtime, s->pcm_buffer_pointer);
remaining_frames = runtime->buffer_size - s->pcm_buffer_pointer;
for (i = 0; i < frames; ++i) {
for (c = 0; c < channels; ++c) {
buffer[p->pcm_positions[c]] =
cpu_to_be32((*src << 8) | 0x42000000);
src++;
}
buffer += s->data_block_quadlets;
if (--remaining_frames == 0)
src = (void *)runtime->dma_area;
}
}
static void read_pcm_s32(struct amdtp_stream *s,
struct snd_pcm_substream *pcm,
__be32 *buffer, unsigned int frames)
{
struct amdtp_am824 *p = s->protocol;
struct snd_pcm_runtime *runtime = pcm->runtime;
unsigned int channels, remaining_frames, i, c;
u32 *dst;
channels = p->pcm_channels;
dst = (void *)runtime->dma_area +
frames_to_bytes(runtime, s->pcm_buffer_pointer);
remaining_frames = runtime->buffer_size - s->pcm_buffer_pointer;
for (i = 0; i < frames; ++i) {
for (c = 0; c < channels; ++c) {
*dst = be32_to_cpu(buffer[p->pcm_positions[c]]) << 8;
dst++;
}
buffer += s->data_block_quadlets;
if (--remaining_frames == 0)
dst = (void *)runtime->dma_area;
}
}
static void write_pcm_silence(struct amdtp_stream *s,
__be32 *buffer, unsigned int frames)
{
struct amdtp_am824 *p = s->protocol;
unsigned int i, c, channels = p->pcm_channels;
for (i = 0; i < frames; ++i) {
for (c = 0; c < channels; ++c)
buffer[p->pcm_positions[c]] = cpu_to_be32(0x40000000);
buffer += s->data_block_quadlets;
}
}
/**
* amdtp_am824_set_pcm_format - set the PCM format
* @s: the AMDTP stream to configure
* @format: the format of the ALSA PCM device
*
* The sample format must be set after the other parameters (rate/PCM channels/
* MIDI) and before the stream is started, and must not be changed while the
* stream is running.
*/
void amdtp_am824_set_pcm_format(struct amdtp_stream *s, snd_pcm_format_t format)
{
struct amdtp_am824 *p = s->protocol;
if (WARN_ON(amdtp_stream_pcm_running(s)))
return;
switch (format) {
default:
WARN_ON(1);
/* fall through */
case SNDRV_PCM_FORMAT_S16:
if (s->direction == AMDTP_OUT_STREAM) {
p->transfer_samples = write_pcm_s16;
break;
}
WARN_ON(1);
/* fall through */
case SNDRV_PCM_FORMAT_S32:
if (s->direction == AMDTP_OUT_STREAM)
p->transfer_samples = write_pcm_s32;
else
p->transfer_samples = read_pcm_s32;
break;
}
}
EXPORT_SYMBOL_GPL(amdtp_am824_set_pcm_format);
/**
* amdtp_am824_add_pcm_hw_constraints - add hw constraints for PCM substream
* @s: the AMDTP stream for AM824 data block, must be initialized.
* @runtime: the PCM substream runtime
*
*/
int amdtp_am824_add_pcm_hw_constraints(struct amdtp_stream *s,
struct snd_pcm_runtime *runtime)
{
int err;
err = amdtp_stream_add_pcm_hw_constraints(s, runtime);
if (err < 0)
return err;
/* AM824 in IEC 61883-6 can deliver 24bit data. */
return snd_pcm_hw_constraint_msbits(runtime, 0, 32, 24);
}
EXPORT_SYMBOL_GPL(amdtp_am824_add_pcm_hw_constraints);
/**
* amdtp_am824_midi_trigger - start/stop playback/capture with a MIDI device
* @s: the AMDTP stream
* @port: index of MIDI port
* @midi: the MIDI device to be started, or %NULL to stop the current device
*
* Call this function on a running isochronous stream to enable the actual
* transmission of MIDI data. This function should be called from the MIDI
* device's .trigger callback.
*/
void amdtp_am824_midi_trigger(struct amdtp_stream *s, unsigned int port,
struct snd_rawmidi_substream *midi)
{
struct amdtp_am824 *p = s->protocol;
if (port < p->midi_ports)
ACCESS_ONCE(p->midi[port]) = midi;
}
EXPORT_SYMBOL_GPL(amdtp_am824_midi_trigger);
/*
* To avoid sending MIDI bytes at too high a rate, assume that the receiving
* device has a FIFO, and track how much it is filled. This values increases
* by one whenever we send one byte in a packet, but the FIFO empties at
* a constant rate independent of our packet rate. One packet has syt_interval
* samples, so the number of bytes that empty out of the FIFO, per packet(!),
* is MIDI_BYTES_PER_SECOND * syt_interval / sample_rate. To avoid storing
* fractional values, the values in midi_fifo_used[] are measured in bytes
* multiplied by the sample rate.
*/
static bool midi_ratelimit_per_packet(struct amdtp_stream *s, unsigned int port)
{
struct amdtp_am824 *p = s->protocol;
int used;
used = p->midi_fifo_used[port];
if (used == 0) /* common shortcut */
return true;
used -= MIDI_BYTES_PER_SECOND * s->syt_interval;
used = max(used, 0);
p->midi_fifo_used[port] = used;
return used < p->midi_fifo_limit;
}
static void midi_rate_use_one_byte(struct amdtp_stream *s, unsigned int port)
{
struct amdtp_am824 *p = s->protocol;
p->midi_fifo_used[port] += amdtp_rate_table[s->sfc];
}
static void write_midi_messages(struct amdtp_stream *s, __be32 *buffer,
unsigned int frames)
{
struct amdtp_am824 *p = s->protocol;
unsigned int f, port;
u8 *b;
for (f = 0; f < frames; f++) {
b = (u8 *)&buffer[p->midi_position];
port = (s->data_block_counter + f) % 8;
if (f < MAX_MIDI_RX_BLOCKS &&
midi_ratelimit_per_packet(s, port) &&
p->midi[port] != NULL &&
snd_rawmidi_transmit(p->midi[port], &b[1], 1) == 1) {
midi_rate_use_one_byte(s, port);
b[0] = 0x81;
} else {
b[0] = 0x80;
b[1] = 0;
}
b[2] = 0;
b[3] = 0;
buffer += s->data_block_quadlets;
}
}
static void read_midi_messages(struct amdtp_stream *s,
__be32 *buffer, unsigned int frames)
{
struct amdtp_am824 *p = s->protocol;
unsigned int f, port;
int len;
u8 *b;
for (f = 0; f < frames; f++) {
port = (s->data_block_counter + f) % 8;
b = (u8 *)&buffer[p->midi_position];
len = b[0] - 0x80;
if ((1 <= len) && (len <= 3) && (p->midi[port]))
snd_rawmidi_receive(p->midi[port], b + 1, len);
buffer += s->data_block_quadlets;
}
}
static unsigned int process_rx_data_blocks(struct amdtp_stream *s, __be32 *buffer,
unsigned int data_blocks, unsigned int *syt)
{
struct amdtp_am824 *p = s->protocol;
struct snd_pcm_substream *pcm = ACCESS_ONCE(s->pcm);
unsigned int pcm_frames;
if (pcm) {
p->transfer_samples(s, pcm, buffer, data_blocks);
pcm_frames = data_blocks * p->frame_multiplier;
} else {
write_pcm_silence(s, buffer, data_blocks);
pcm_frames = 0;
}
if (p->midi_ports)
write_midi_messages(s, buffer, data_blocks);
return pcm_frames;
}
static unsigned int process_tx_data_blocks(struct amdtp_stream *s, __be32 *buffer,
unsigned int data_blocks, unsigned int *syt)
{
struct amdtp_am824 *p = s->protocol;
struct snd_pcm_substream *pcm = ACCESS_ONCE(s->pcm);
unsigned int pcm_frames;
if (pcm) {
p->transfer_samples(s, pcm, buffer, data_blocks);
pcm_frames = data_blocks * p->frame_multiplier;
} else {
pcm_frames = 0;
}
if (p->midi_ports)
read_midi_messages(s, buffer, data_blocks);
return pcm_frames;
}
/**
* amdtp_am824_init - initialize an AMDTP stream structure to handle AM824
* data block
* @s: the AMDTP stream to initialize
* @unit: the target of the stream
* @dir: the direction of stream
* @flags: the packet transmission method to use
*/
int amdtp_am824_init(struct amdtp_stream *s, struct fw_unit *unit,
enum amdtp_stream_direction dir, enum cip_flags flags)
{
amdtp_stream_process_data_blocks_t process_data_blocks;
if (dir == AMDTP_IN_STREAM)
process_data_blocks = process_tx_data_blocks;
else
process_data_blocks = process_rx_data_blocks;
return amdtp_stream_init(s, unit, dir, flags, CIP_FMT_AM,
process_data_blocks,
sizeof(struct amdtp_am824));
}
EXPORT_SYMBOL_GPL(amdtp_am824_init);
