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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * amdtp-dot.c - a part of driver for Digidesign Digi 002/003 family4 *5 * Copyright (c) 2014-2015 Takashi Sakamoto6 * Copyright (C) 2012 Robin Gareus <robin@gareus.org>7 * Copyright (C) 2012 Damien Zammit <damien@zamaudio.com>8 */9 10#include <sound/pcm.h>11#include "digi00x.h"12 13#define CIP_FMT_AM 0x1014 15/* 'Clock-based rate control mode' is just supported. */16#define AMDTP_FDF_AM824 0x0017 18/*19 * Nominally 3125 bytes/second, but the MIDI port's clock might be20 * 1% too slow, and the bus clock 100 ppm too fast.21 */22#define MIDI_BYTES_PER_SECOND 309323 24/*25 * Several devices look only at the first eight data blocks.26 * In any case, this is more than enough for the MIDI data rate.27 */28#define MAX_MIDI_RX_BLOCKS 829 30/* 3 = MAX(DOT_MIDI_IN_PORTS, DOT_MIDI_OUT_PORTS) + 1. */31#define MAX_MIDI_PORTS 332 33/*34 * The double-oh-three algorithm was discovered by Robin Gareus and Damien35 * Zammit in 2012, with reverse-engineering for Digi 003 Rack.36 */37struct dot_state {38 u8 carry;39 u8 idx;40 unsigned int off;41};42 43struct amdtp_dot {44 unsigned int pcm_channels;45 struct dot_state state;46 47 struct snd_rawmidi_substream *midi[MAX_MIDI_PORTS];48 int midi_fifo_used[MAX_MIDI_PORTS];49 int midi_fifo_limit;50};51 52/*53 * double-oh-three look up table54 *55 * @param idx index byte (audio-sample data) 0x00..0xff56 * @param off channel offset shift57 * @return salt to XOR with given data58 */59#define BYTE_PER_SAMPLE (4)60#define MAGIC_DOT_BYTE (2)61#define MAGIC_BYTE_OFF(x) (((x) * BYTE_PER_SAMPLE) + MAGIC_DOT_BYTE)62static u8 dot_scrt(const u8 idx, const unsigned int off)63{64 /*65 * the length of the added pattern only depends on the lower nibble66 * of the last non-zero data67 */68 static const u8 len[16] = {0, 1, 3, 5, 7, 9, 11, 13, 14,69 12, 10, 8, 6, 4, 2, 0};70 71 /*72 * the lower nibble of the salt. Interleaved sequence.73 * this is walked backwards according to len[]74 */75 static const u8 nib[15] = {0x8, 0x7, 0x9, 0x6, 0xa, 0x5, 0xb, 0x4,76 0xc, 0x3, 0xd, 0x2, 0xe, 0x1, 0xf};77 78 /* circular list for the salt's hi nibble. */79 static const u8 hir[15] = {0x0, 0x6, 0xf, 0x8, 0x7, 0x5, 0x3, 0x4,80 0xc, 0xd, 0xe, 0x1, 0x2, 0xb, 0xa};81 82 /*83 * start offset for upper nibble mapping.84 * note: 9 is /special/. In the case where the high nibble == 0x9,85 * hir[] is not used and - coincidentally - the salt's hi nibble is86 * 0x09 regardless of the offset.87 */88 static const u8 hio[16] = {0, 11, 12, 6, 7, 5, 1, 4,89 3, 0x00, 14, 13, 8, 9, 10, 2};90 91 const u8 ln = idx & 0xf;92 const u8 hn = (idx >> 4) & 0xf;93 const u8 hr = (hn == 0x9) ? 0x9 : hir[(hio[hn] + off) % 15];94 95 if (len[ln] < off)96 return 0x00;97 98 return ((nib[14 + off - len[ln]]) | (hr << 4));99}100 101static void dot_encode_step(struct dot_state *state, __be32 *const buffer)102{103 u8 * const data = (u8 *) buffer;104 105 if (data[MAGIC_DOT_BYTE] != 0x00) {106 state->off = 0;107 state->idx = data[MAGIC_DOT_BYTE] ^ state->carry;108 }109 data[MAGIC_DOT_BYTE] ^= state->carry;110 state->carry = dot_scrt(state->idx, ++(state->off));111}112 113int amdtp_dot_set_parameters(struct amdtp_stream *s, unsigned int rate,114 unsigned int pcm_channels)115{116 struct amdtp_dot *p = s->protocol;117 int err;118 119 if (amdtp_stream_running(s))120 return -EBUSY;121 122 /*123 * A first data channel is for MIDI messages, the rest is Multi Bit124 * Linear Audio data channel.125 */126 err = amdtp_stream_set_parameters(s, rate, pcm_channels + 1, 1);127 if (err < 0)128 return err;129 130 s->ctx_data.rx.fdf = AMDTP_FDF_AM824 | s->sfc;131 132 p->pcm_channels = pcm_channels;133 134 /*135 * We do not know the actual MIDI FIFO size of most devices. Just136 * assume two bytes, i.e., one byte can be received over the bus while137 * the previous one is transmitted over MIDI.138 * (The value here is adjusted for midi_ratelimit_per_packet().)139 */140 p->midi_fifo_limit = rate - MIDI_BYTES_PER_SECOND * s->syt_interval + 1;141 142 return 0;143}144 145static void write_pcm_s32(struct amdtp_stream *s, struct snd_pcm_substream *pcm,146 __be32 *buffer, unsigned int frames,147 unsigned int pcm_frames)148{149 struct amdtp_dot *p = s->protocol;150 unsigned int channels = p->pcm_channels;151 struct snd_pcm_runtime *runtime = pcm->runtime;152 unsigned int pcm_buffer_pointer;153 int remaining_frames;154 const u32 *src;155 int i, c;156 157 pcm_buffer_pointer = s->pcm_buffer_pointer + pcm_frames;158 pcm_buffer_pointer %= runtime->buffer_size;159 160 src = (void *)runtime->dma_area +161 frames_to_bytes(runtime, pcm_buffer_pointer);162 remaining_frames = runtime->buffer_size - pcm_buffer_pointer;163 164 buffer++;165 for (i = 0; i < frames; ++i) {166 for (c = 0; c < channels; ++c) {167 buffer[c] = cpu_to_be32((*src >> 8) | 0x40000000);168 dot_encode_step(&p->state, &buffer[c]);169 src++;170 }171 buffer += s->data_block_quadlets;172 if (--remaining_frames == 0)173 src = (void *)runtime->dma_area;174 }175}176 177static void read_pcm_s32(struct amdtp_stream *s, struct snd_pcm_substream *pcm,178 __be32 *buffer, unsigned int frames,179 unsigned int pcm_frames)180{181 struct amdtp_dot *p = s->protocol;182 unsigned int channels = p->pcm_channels;183 struct snd_pcm_runtime *runtime = pcm->runtime;184 unsigned int pcm_buffer_pointer;185 int remaining_frames;186 u32 *dst;187 int i, c;188 189 pcm_buffer_pointer = s->pcm_buffer_pointer + pcm_frames;190 pcm_buffer_pointer %= runtime->buffer_size;191 192 dst = (void *)runtime->dma_area +193 frames_to_bytes(runtime, pcm_buffer_pointer);194 remaining_frames = runtime->buffer_size - pcm_buffer_pointer;195 196 buffer++;197 for (i = 0; i < frames; ++i) {198 for (c = 0; c < channels; ++c) {199 *dst = be32_to_cpu(buffer[c]) << 8;200 dst++;201 }202 buffer += s->data_block_quadlets;203 if (--remaining_frames == 0)204 dst = (void *)runtime->dma_area;205 }206}207 208static void write_pcm_silence(struct amdtp_stream *s, __be32 *buffer,209 unsigned int data_blocks)210{211 struct amdtp_dot *p = s->protocol;212 unsigned int channels, i, c;213 214 channels = p->pcm_channels;215 216 buffer++;217 for (i = 0; i < data_blocks; ++i) {218 for (c = 0; c < channels; ++c)219 buffer[c] = cpu_to_be32(0x40000000);220 buffer += s->data_block_quadlets;221 }222}223 224static bool midi_ratelimit_per_packet(struct amdtp_stream *s, unsigned int port)225{226 struct amdtp_dot *p = s->protocol;227 int used;228 229 used = p->midi_fifo_used[port];230 if (used == 0)231 return true;232 233 used -= MIDI_BYTES_PER_SECOND * s->syt_interval;234 used = max(used, 0);235 p->midi_fifo_used[port] = used;236 237 return used < p->midi_fifo_limit;238}239 240static inline void midi_use_bytes(struct amdtp_stream *s,241 unsigned int port, unsigned int count)242{243 struct amdtp_dot *p = s->protocol;244 245 p->midi_fifo_used[port] += amdtp_rate_table[s->sfc] * count;246}247 248static void write_midi_messages(struct amdtp_stream *s, __be32 *buffer,249 unsigned int data_blocks, unsigned int data_block_counter)250{251 struct amdtp_dot *p = s->protocol;252 unsigned int f, port;253 int len;254 u8 *b;255 256 for (f = 0; f < data_blocks; f++) {257 port = (data_block_counter + f) % 8;258 b = (u8 *)&buffer[0];259 260 len = 0;261 if (port < MAX_MIDI_PORTS &&262 midi_ratelimit_per_packet(s, port) &&263 p->midi[port] != NULL)264 len = snd_rawmidi_transmit(p->midi[port], b + 1, 2);265 266 if (len > 0) {267 /*268 * Upper 4 bits of LSB represent port number.269 * - 0000b: physical MIDI port 1.270 * - 0010b: physical MIDI port 2.271 * - 1110b: console MIDI port.272 */273 if (port == 2)274 b[3] = 0xe0;275 else if (port == 1)276 b[3] = 0x20;277 else278 b[3] = 0x00;279 b[3] |= len;280 midi_use_bytes(s, port, len);281 } else {282 b[1] = 0;283 b[2] = 0;284 b[3] = 0;285 }286 b[0] = 0x80;287 288 buffer += s->data_block_quadlets;289 }290}291 292static void read_midi_messages(struct amdtp_stream *s, __be32 *buffer,293 unsigned int data_blocks)294{295 struct amdtp_dot *p = s->protocol;296 unsigned int f, port, len;297 u8 *b;298 299 for (f = 0; f < data_blocks; f++) {300 b = (u8 *)&buffer[0];301 302 len = b[3] & 0x0f;303 if (len > 0) {304 /*305 * Upper 4 bits of LSB represent port number.306 * - 0000b: physical MIDI port 1. Use port 0.307 * - 1110b: console MIDI port. Use port 2.308 */309 if (b[3] >> 4 > 0)310 port = 2;311 else312 port = 0;313 314 if (port < MAX_MIDI_PORTS && p->midi[port])315 snd_rawmidi_receive(p->midi[port], b + 1, len);316 }317 318 buffer += s->data_block_quadlets;319 }320}321 322int amdtp_dot_add_pcm_hw_constraints(struct amdtp_stream *s,323 struct snd_pcm_runtime *runtime)324{325 int err;326 327 /* This protocol delivers 24 bit data in 32bit data channel. */328 err = snd_pcm_hw_constraint_msbits(runtime, 0, 32, 24);329 if (err < 0)330 return err;331 332 return amdtp_stream_add_pcm_hw_constraints(s, runtime);333}334 335void amdtp_dot_midi_trigger(struct amdtp_stream *s, unsigned int port,336 struct snd_rawmidi_substream *midi)337{338 struct amdtp_dot *p = s->protocol;339 340 if (port < MAX_MIDI_PORTS)341 WRITE_ONCE(p->midi[port], midi);342}343 344static void process_ir_ctx_payloads(struct amdtp_stream *s, const struct pkt_desc *desc,345 unsigned int count, struct snd_pcm_substream *pcm)346{347 unsigned int pcm_frames = 0;348 int i;349 350 for (i = 0; i < count; ++i) {351 __be32 *buf = desc->ctx_payload;352 unsigned int data_blocks = desc->data_blocks;353 354 if (pcm) {355 read_pcm_s32(s, pcm, buf, data_blocks, pcm_frames);356 pcm_frames += data_blocks;357 }358 359 read_midi_messages(s, buf, data_blocks);360 361 desc = amdtp_stream_next_packet_desc(s, desc);362 }363}364 365static void process_it_ctx_payloads(struct amdtp_stream *s, const struct pkt_desc *desc,366 unsigned int count, struct snd_pcm_substream *pcm)367{368 unsigned int pcm_frames = 0;369 int i;370 371 for (i = 0; i < count; ++i) {372 __be32 *buf = desc->ctx_payload;373 unsigned int data_blocks = desc->data_blocks;374 375 if (pcm) {376 write_pcm_s32(s, pcm, buf, data_blocks, pcm_frames);377 pcm_frames += data_blocks;378 } else {379 write_pcm_silence(s, buf, data_blocks);380 }381 382 write_midi_messages(s, buf, data_blocks,383 desc->data_block_counter);384 385 desc = amdtp_stream_next_packet_desc(s, desc);386 }387}388 389int amdtp_dot_init(struct amdtp_stream *s, struct fw_unit *unit,390 enum amdtp_stream_direction dir)391{392 amdtp_stream_process_ctx_payloads_t process_ctx_payloads;393 unsigned int flags = CIP_NONBLOCKING | CIP_UNAWARE_SYT;394 395 // Use different mode between incoming/outgoing.396 if (dir == AMDTP_IN_STREAM)397 process_ctx_payloads = process_ir_ctx_payloads;398 else399 process_ctx_payloads = process_it_ctx_payloads;400 401 return amdtp_stream_init(s, unit, dir, flags, CIP_FMT_AM,402 process_ctx_payloads, sizeof(struct amdtp_dot));403}404 405void amdtp_dot_reset(struct amdtp_stream *s)406{407 struct amdtp_dot *p = s->protocol;408 409 p->state.carry = 0x00;410 p->state.idx = 0x00;411 p->state.off = 0;412}413