// SPDX-License-Identifier: GPL-2.0-only
/*
* amdtp-dot.c - a part of driver for Digidesign Digi 002/003 family
*
* Copyright (c) 2014-2015 Takashi Sakamoto
* Copyright (C) 2012 Robin Gareus <[email protected]>
* Copyright (C) 2012 Damien Zammit <[email protected]>
*/
#include <sound/pcm.h>
#include "digi00x.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
/* 3 = MAX(DOT_MIDI_IN_PORTS, DOT_MIDI_OUT_PORTS) + 1. */
#define MAX_MIDI_PORTS 3
/*
* The double-oh-three algorithm was discovered by Robin Gareus and Damien
* Zammit in 2012, with reverse-engineering for Digi 003 Rack.
*/
struct dot_state {
u8 carry;
u8 idx;
unsigned int off;
};
struct amdtp_dot {
unsigned int pcm_channels;
struct dot_state state;
struct snd_rawmidi_substream *midi[MAX_MIDI_PORTS];
int midi_fifo_used[MAX_MIDI_PORTS];
int midi_fifo_limit;
};
/*
* double-oh-three look up table
*
* @param idx index byte (audio-sample data) 0x00..0xff
* @param off channel offset shift
* @return salt to XOR with given data
*/
#define BYTE_PER_SAMPLE (4)
#define MAGIC_DOT_BYTE (2)
#define MAGIC_BYTE_OFF(x) (((x) * BYTE_PER_SAMPLE) + MAGIC_DOT_BYTE)
static u8 dot_scrt(const u8 idx, const unsigned int off)
{
/*
* the length of the added pattern only depends on the lower nibble
* of the last non-zero data
*/
static const u8 len[16] = {0, 1, 3, 5, 7, 9, 11, 13, 14,
12, 10, 8, 6, 4, 2, 0};
/*
* the lower nibble of the salt. Interleaved sequence.
* this is walked backwards according to len[]
*/
static const u8 nib[15] = {0x8, 0x7, 0x9, 0x6, 0xa, 0x5, 0xb, 0x4,
0xc, 0x3, 0xd, 0x2, 0xe, 0x1, 0xf};
/* circular list for the salt's hi nibble. */
static const u8 hir[15] = {0x0, 0x6, 0xf, 0x8, 0x7, 0x5, 0x3, 0x4,
0xc, 0xd, 0xe, 0x1, 0x2, 0xb, 0xa};
/*
* start offset for upper nibble mapping.
* note: 9 is /special/. In the case where the high nibble == 0x9,
* hir[] is not used and - coincidentally - the salt's hi nibble is
* 0x09 regardless of the offset.
*/
static const u8 hio[16] = {0, 11, 12, 6, 7, 5, 1, 4,
3, 0x00, 14, 13, 8, 9, 10, 2};
const u8 ln = idx & 0xf;
const u8 hn = (idx >> 4) & 0xf;
const u8 hr = (hn == 0x9) ? 0x9 : hir[(hio[hn] + off) % 15];
if (len[ln] < off)
return 0x00;
return ((nib[14 + off - len[ln]]) | (hr << 4));
}
static void dot_encode_step(struct dot_state *state, __be32 *const buffer)
{
u8 * const data = (u8 *) buffer;
if (data[MAGIC_DOT_BYTE] != 0x00) {
state->off = 0;
state->idx = data[MAGIC_DOT_BYTE] ^ state->carry;
}
data[MAGIC_DOT_BYTE] ^= state->carry;
state->carry = dot_scrt(state->idx, ++(state->off));
}
int amdtp_dot_set_parameters(struct amdtp_stream *s, unsigned int rate,
unsigned int pcm_channels)
{
struct amdtp_dot *p = s->protocol;
int err;
if (amdtp_stream_running(s))
return -EBUSY;
/*
* A first data channel is for MIDI messages, the rest is Multi Bit
* Linear Audio data channel.
*/
err = amdtp_stream_set_parameters(s, rate, pcm_channels + 1, 1);
if (err < 0)
return err;
s->ctx_data.rx.fdf = AMDTP_FDF_AM824 | s->sfc;
p->pcm_channels = 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;
}
static void write_pcm_s32(struct amdtp_stream *s, struct snd_pcm_substream *pcm,
__be32 *buffer, unsigned int frames,
unsigned int pcm_frames)
{
struct amdtp_dot *p = s->protocol;
unsigned int channels = p->pcm_channels;
struct snd_pcm_runtime *runtime = pcm->runtime;
unsigned int pcm_buffer_pointer;
int remaining_frames;
const u32 *src;
int i, c;
pcm_buffer_pointer = s->pcm_buffer_pointer + pcm_frames;
pcm_buffer_pointer %= runtime->buffer_size;
src = (void *)runtime->dma_area +
frames_to_bytes(runtime, pcm_buffer_pointer);
remaining_frames = runtime->buffer_size - pcm_buffer_pointer;
buffer++;
for (i = 0; i < frames; ++i) {
for (c = 0; c < channels; ++c) {
buffer[c] = cpu_to_be32((*src >> 8) | 0x40000000);
dot_encode_step(&p->state, &buffer[c]);
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,
unsigned int pcm_frames)
{
struct amdtp_dot *p = s->protocol;
unsigned int channels = p->pcm_channels;
struct snd_pcm_runtime *runtime = pcm->runtime;
unsigned int pcm_buffer_pointer;
int remaining_frames;
u32 *dst;
int i, c;
pcm_buffer_pointer = s->pcm_buffer_pointer + pcm_frames;
pcm_buffer_pointer %= runtime->buffer_size;
dst = (void *)runtime->dma_area +
frames_to_bytes(runtime, pcm_buffer_pointer);
remaining_frames = runtime->buffer_size - pcm_buffer_pointer;
buffer++;
for (i = 0; i < frames; ++i) {
for (c = 0; c < channels; ++c) {
*dst = be32_to_cpu(buffer[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 data_blocks)
{
struct amdtp_dot *p = s->protocol;
unsigned int channels, i, c;
channels = p->pcm_channels;
buffer++;
for (i = 0; i < data_blocks; ++i) {
for (c = 0; c < channels; ++c)
buffer[c] = cpu_to_be32(0x40000000);
buffer += s->data_block_quadlets;
}
}
static bool midi_ratelimit_per_packet(struct amdtp_stream *s, unsigned int port)
{
struct amdtp_dot *p = s->protocol;
int used;
used = p->midi_fifo_used[port];
if (used == 0)
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 inline void midi_use_bytes(struct amdtp_stream *s,
unsigned int port, unsigned int count)
{
struct amdtp_dot *p = s->protocol;
p->midi_fifo_used[port] += amdtp_rate_table[s->sfc] * count;
}
static void write_midi_messages(struct amdtp_stream *s, __be32 *buffer,
unsigned int data_blocks, unsigned int data_block_counter)
{
struct amdtp_dot *p = s->protocol;
unsigned int f, port;
int len;
u8 *b;
for (f = 0; f < data_blocks; f++) {
port = (data_block_counter + f) % 8;
b = (u8 *)&buffer[0];
len = 0;
if (port < MAX_MIDI_PORTS &&
midi_ratelimit_per_packet(s, port) &&
p->midi[port] != NULL)
len = snd_rawmidi_transmit(p->midi[port], b + 1, 2);
if (len > 0) {
/*
* Upper 4 bits of LSB represent port number.
* - 0000b: physical MIDI port 1.
* - 0010b: physical MIDI port 2.
* - 1110b: console MIDI port.
*/
if (port == 2)
b[3] = 0xe0;
else if (port == 1)
b[3] = 0x20;
else
b[3] = 0x00;
b[3] |= len;
midi_use_bytes(s, port, len);
} else {
b[1] = 0;
b[2] = 0;
b[3] = 0;
}
b[0] = 0x80;
buffer += s->data_block_quadlets;
}
}
static void read_midi_messages(struct amdtp_stream *s, __be32 *buffer,
unsigned int data_blocks)
{
struct amdtp_dot *p = s->protocol;
unsigned int f, port, len;
u8 *b;
for (f = 0; f < data_blocks; f++) {
b = (u8 *)&buffer[0];
len = b[3] & 0x0f;
if (len > 0) {
/*
* Upper 4 bits of LSB represent port number.
* - 0000b: physical MIDI port 1. Use port 0.
* - 1110b: console MIDI port. Use port 2.
*/
if (b[3] >> 4 > 0)
port = 2;
else
port = 0;
if (port < MAX_MIDI_PORTS && p->midi[port])
snd_rawmidi_receive(p->midi[port], b + 1, len);
}
buffer += s->data_block_quadlets;
}
}
int amdtp_dot_add_pcm_hw_constraints(struct amdtp_stream *s,
struct snd_pcm_runtime *runtime)
{
int err;
/* This protocol delivers 24 bit data in 32bit data channel. */
err = snd_pcm_hw_constraint_msbits(runtime, 0, 32, 24);
if (err < 0)
return err;
return amdtp_stream_add_pcm_hw_constraints(s, runtime);
}
void amdtp_dot_midi_trigger(struct amdtp_stream *s, unsigned int port,
struct snd_rawmidi_substream *midi)
{
struct amdtp_dot *p = s->protocol;
if (port < MAX_MIDI_PORTS)
WRITE_ONCE(p->midi[port], midi);
}
static void process_ir_ctx_payloads(struct amdtp_stream *s, const struct pkt_desc *desc,
unsigned int count, struct snd_pcm_substream *pcm)
{
unsigned int pcm_frames = 0;
int i;
for (i = 0; i < count; ++i) {
__be32 *buf = desc->ctx_payload;
unsigned int data_blocks = desc->data_blocks;
if (pcm) {
read_pcm_s32(s, pcm, buf, data_blocks, pcm_frames);
pcm_frames += data_blocks;
}
read_midi_messages(s, buf, data_blocks);
desc = amdtp_stream_next_packet_desc(s, desc);
}
}
static void process_it_ctx_payloads(struct amdtp_stream *s, const struct pkt_desc *desc,
unsigned int count, struct snd_pcm_substream *pcm)
{
unsigned int pcm_frames = 0;
int i;
for (i = 0; i < count; ++i) {
__be32 *buf = desc->ctx_payload;
unsigned int data_blocks = desc->data_blocks;
if (pcm) {
write_pcm_s32(s, pcm, buf, data_blocks, pcm_frames);
pcm_frames += data_blocks;
} else {
write_pcm_silence(s, buf, data_blocks);
}
write_midi_messages(s, buf, data_blocks,
desc->data_block_counter);
desc = amdtp_stream_next_packet_desc(s, desc);
}
}
int amdtp_dot_init(struct amdtp_stream *s, struct fw_unit *unit,
enum amdtp_stream_direction dir)
{
amdtp_stream_process_ctx_payloads_t process_ctx_payloads;
unsigned int flags = CIP_NONBLOCKING | CIP_UNAWARE_SYT;
// Use different mode between incoming/outgoing.
if (dir == AMDTP_IN_STREAM)
process_ctx_payloads = process_ir_ctx_payloads;
else
process_ctx_payloads = process_it_ctx_payloads;
return amdtp_stream_init(s, unit, dir, flags, CIP_FMT_AM,
process_ctx_payloads, sizeof(struct amdtp_dot));
}
void amdtp_dot_reset(struct amdtp_stream *s)
{
struct amdtp_dot *p = s->protocol;
p->state.carry = 0x00;
p->state.idx = 0x00;
p->state.off = 0;
}
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