sound/firewire/amdtp-am824.c

   1 /*
   2  * AM824 format in Audio and Music Data Transmission Protocol (IEC 61883-6)
   3  *
   4  * Copyright (c) Clemens Ladisch <clemens@ladisch.de>
   5  * Copyright (c) 2015 Takashi Sakamoto <o-takashi@sakamocchi.jp>
   6  *
   7  * Licensed under the terms of the GNU General Public License, version 2.
   8  */
   9
  10 #include <linux/slab.h>
  11
  12 #include "amdtp-am824.h"
  13
  14 #define CIP_FMT_AM              0x10
  15
  16 /* "Clock-based rate control mode" is just supported. */
  17 #define AMDTP_FDF_AM824         0x00
  18
  19 /*
  20  * Nominally 3125 bytes/second, but the MIDI port's clock might be
  21  * 1% too slow, and the bus clock 100 ppm too fast.
  22  */
  23 #define MIDI_BYTES_PER_SECOND   3093
  24
  25 /*
  26  * Several devices look only at the first eight data blocks.
  27  * In any case, this is more than enough for the MIDI data rate.
  28  */
  29 #define MAX_MIDI_RX_BLOCKS      8
  30
  31 struct amdtp_am824 {
  32         struct snd_rawmidi_substream *midi[AM824_MAX_CHANNELS_FOR_MIDI * 8];
  33         int midi_fifo_limit;
  34         int midi_fifo_used[AM824_MAX_CHANNELS_FOR_MIDI * 8];
  35         unsigned int pcm_channels;
  36         unsigned int midi_ports;
  37
  38         u8 pcm_positions[AM824_MAX_CHANNELS_FOR_PCM];
  39         u8 midi_position;
  40
  41         void (*transfer_samples)(struct amdtp_stream *s,
  42                                  struct snd_pcm_substream *pcm,
  43                                  __be32 *buffer, unsigned int frames);
  44
  45         unsigned int frame_multiplier;
  46 };
  47
  48 /**
  49  * amdtp_am824_set_parameters - set stream parameters
  50  * @s: the AMDTP stream to configure
  51  * @rate: the sample rate
  52  * @pcm_channels: the number of PCM samples in each data block, to be encoded
  53  *                as AM824 multi-bit linear audio
  54  * @midi_ports: the number of MIDI ports (i.e., MPX-MIDI Data Channels)
  55  * @double_pcm_frames: one data block transfers two PCM frames
  56  *
  57  * The parameters must be set before the stream is started, and must not be
  58  * changed while the stream is running.
  59  */
  60 int amdtp_am824_set_parameters(struct amdtp_stream *s, unsigned int rate,
  61                                unsigned int pcm_channels,
  62                                unsigned int midi_ports,
  63                                bool double_pcm_frames)
  64 {
  65         struct amdtp_am824 *p = s->protocol;
  66         unsigned int midi_channels;
  67         unsigned int i;
  68         int err;
  69
  70         if (amdtp_stream_running(s))
  71                 return -EINVAL;
  72
  73         if (pcm_channels > AM824_MAX_CHANNELS_FOR_PCM)
  74                 return -EINVAL;
  75
  76         midi_channels = DIV_ROUND_UP(midi_ports, 8);
  77         if (midi_channels > AM824_MAX_CHANNELS_FOR_MIDI)
  78                 return -EINVAL;
  79
  80         if (WARN_ON(amdtp_stream_running(s)) ||
  81             WARN_ON(pcm_channels > AM824_MAX_CHANNELS_FOR_PCM) ||
  82             WARN_ON(midi_channels > AM824_MAX_CHANNELS_FOR_MIDI))
  83                 return -EINVAL;
  84
  85         err = amdtp_stream_set_parameters(s, rate,
  86                                           pcm_channels + midi_channels);
  87         if (err < 0)
  88                 return err;
  89
  90         s->fdf = AMDTP_FDF_AM824 | s->sfc;
  91
  92         p->pcm_channels = pcm_channels;
  93         p->midi_ports = midi_ports;
  94
  95         /*
  96          * In IEC 61883-6, one data block represents one event. In ALSA, one
  97          * event equals to one PCM frame. But Dice has a quirk at higher
  98          * sampling rate to transfer two PCM frames in one data block.
  99          */
 100         if (double_pcm_frames)
 101                 p->frame_multiplier = 2;
 102         else
 103                 p->frame_multiplier = 1;
 104
 105         /* init the position map for PCM and MIDI channels */
 106         for (i = 0; i < pcm_channels; i++)
 107                 p->pcm_positions[i] = i;
 108         p->midi_position = p->pcm_channels;
 109
 110         /*
 111          * We do not know the actual MIDI FIFO size of most devices.  Just
 112          * assume two bytes, i.e., one byte can be received over the bus while
 113          * the previous one is transmitted over MIDI.
 114          * (The value here is adjusted for midi_ratelimit_per_packet().)
 115          */
 116         p->midi_fifo_limit = rate - MIDI_BYTES_PER_SECOND * s->syt_interval + 1;
 117
 118         return 0;
 119 }
 120 EXPORT_SYMBOL_GPL(amdtp_am824_set_parameters);
 121
 122 /**
 123  * amdtp_am824_set_pcm_position - set an index of data channel for a channel
 124  *                                of PCM frame
 125  * @s: the AMDTP stream
 126  * @index: the index of data channel in an data block
 127  * @position: the channel of PCM frame
 128  */
 129 void amdtp_am824_set_pcm_position(struct amdtp_stream *s, unsigned int index,
 130                                  unsigned int position)
 131 {
 132         struct amdtp_am824 *p = s->protocol;
 133
 134         if (index < p->pcm_channels)
 135                 p->pcm_positions[index] = position;
 136 }
 137 EXPORT_SYMBOL_GPL(amdtp_am824_set_pcm_position);
 138
 139 /**
 140  * amdtp_am824_set_midi_position - set a index of data channel for MIDI
 141  *                                 conformant data channel
 142  * @s: the AMDTP stream
 143  * @position: the index of data channel in an data block
 144  */
 145 void amdtp_am824_set_midi_position(struct amdtp_stream *s,
 146                                    unsigned int position)
 147 {
 148         struct amdtp_am824 *p = s->protocol;
 149
 150         p->midi_position = position;
 151 }
 152 EXPORT_SYMBOL_GPL(amdtp_am824_set_midi_position);
 153
 154 static void write_pcm_s32(struct amdtp_stream *s,
 155                           struct snd_pcm_substream *pcm,
 156                           __be32 *buffer, unsigned int frames)
 157 {
 158         struct amdtp_am824 *p = s->protocol;
 159         struct snd_pcm_runtime *runtime = pcm->runtime;
 160         unsigned int channels, remaining_frames, i, c;
 161         const u32 *src;
 162
 163         channels = p->pcm_channels;
 164         src = (void *)runtime->dma_area +
 165                         frames_to_bytes(runtime, s->pcm_buffer_pointer);
 166         remaining_frames = runtime->buffer_size - s->pcm_buffer_pointer;
 167
 168         for (i = 0; i < frames; ++i) {
 169                 for (c = 0; c < channels; ++c) {
 170                         buffer[p->pcm_positions[c]] =
 171                                         cpu_to_be32((*src >> 8) | 0x40000000);
 172                         src++;
 173                 }
 174                 buffer += s->data_block_quadlets;
 175                 if (--remaining_frames == 0)
 176                         src = (void *)runtime->dma_area;
 177         }
 178 }
 179
 180 static void write_pcm_s16(struct amdtp_stream *s,
 181                           struct snd_pcm_substream *pcm,
 182                           __be32 *buffer, unsigned int frames)
 183 {
 184         struct amdtp_am824 *p = s->protocol;
 185         struct snd_pcm_runtime *runtime = pcm->runtime;
 186         unsigned int channels, remaining_frames, i, c;
 187         const u16 *src;
 188
 189         channels = p->pcm_channels;
 190         src = (void *)runtime->dma_area +
 191                         frames_to_bytes(runtime, s->pcm_buffer_pointer);
 192         remaining_frames = runtime->buffer_size - s->pcm_buffer_pointer;
 193
 194         for (i = 0; i < frames; ++i) {
 195                 for (c = 0; c < channels; ++c) {
 196                         buffer[p->pcm_positions[c]] =
 197                                         cpu_to_be32((*src << 8) | 0x42000000);
 198                         src++;
 199                 }
 200                 buffer += s->data_block_quadlets;
 201                 if (--remaining_frames == 0)
 202                         src = (void *)runtime->dma_area;
 203         }
 204 }
 205
 206 static void read_pcm_s32(struct amdtp_stream *s,
 207                          struct snd_pcm_substream *pcm,
 208                          __be32 *buffer, unsigned int frames)
 209 {
 210         struct amdtp_am824 *p = s->protocol;
 211         struct snd_pcm_runtime *runtime = pcm->runtime;
 212         unsigned int channels, remaining_frames, i, c;
 213         u32 *dst;
 214
 215         channels = p->pcm_channels;
 216         dst  = (void *)runtime->dma_area +
 217                         frames_to_bytes(runtime, s->pcm_buffer_pointer);
 218         remaining_frames = runtime->buffer_size - s->pcm_buffer_pointer;
 219
 220         for (i = 0; i < frames; ++i) {
 221                 for (c = 0; c < channels; ++c) {
 222                         *dst = be32_to_cpu(buffer[p->pcm_positions[c]]) << 8;
 223                         dst++;
 224                 }
 225                 buffer += s->data_block_quadlets;
 226                 if (--remaining_frames == 0)
 227                         dst = (void *)runtime->dma_area;
 228         }
 229 }
 230
 231 static void write_pcm_silence(struct amdtp_stream *s,
 232                               __be32 *buffer, unsigned int frames)
 233 {
 234         struct amdtp_am824 *p = s->protocol;
 235         unsigned int i, c, channels = p->pcm_channels;
 236
 237         for (i = 0; i < frames; ++i) {
 238                 for (c = 0; c < channels; ++c)
 239                         buffer[p->pcm_positions[c]] = cpu_to_be32(0x40000000);
 240                 buffer += s->data_block_quadlets;
 241         }
 242 }
 243
 244 /**
 245  * amdtp_am824_set_pcm_format - set the PCM format
 246  * @s: the AMDTP stream to configure
 247  * @format: the format of the ALSA PCM device
 248  *
 249  * The sample format must be set after the other parameters (rate/PCM channels/
 250  * MIDI) and before the stream is started, and must not be changed while the
 251  * stream is running.
 252  */
 253 void amdtp_am824_set_pcm_format(struct amdtp_stream *s, snd_pcm_format_t format)
 254 {
 255         struct amdtp_am824 *p = s->protocol;
 256
 257         if (WARN_ON(amdtp_stream_pcm_running(s)))
 258                 return;
 259
 260         switch (format) {
 261         default:
 262                 WARN_ON(1);
 263                 /* fall through */
 264         case SNDRV_PCM_FORMAT_S16:
 265                 if (s->direction == AMDTP_OUT_STREAM) {
 266                         p->transfer_samples = write_pcm_s16;
 267                         break;
 268                 }
 269                 WARN_ON(1);
 270                 /* fall through */
 271         case SNDRV_PCM_FORMAT_S32:
 272                 if (s->direction == AMDTP_OUT_STREAM)
 273                         p->transfer_samples = write_pcm_s32;
 274                 else
 275                         p->transfer_samples = read_pcm_s32;
 276                 break;
 277         }
 278 }
 279 EXPORT_SYMBOL_GPL(amdtp_am824_set_pcm_format);
 280
 281 /**
 282  * amdtp_am824_add_pcm_hw_constraints - add hw constraints for PCM substream
 283  * @s:          the AMDTP stream for AM824 data block, must be initialized.
 284  * @runtime:    the PCM substream runtime
 285  *
 286  */
 287 int amdtp_am824_add_pcm_hw_constraints(struct amdtp_stream *s,
 288                                        struct snd_pcm_runtime *runtime)
 289 {
 290         int err;
 291
 292         err = amdtp_stream_add_pcm_hw_constraints(s, runtime);
 293         if (err < 0)
 294                 return err;
 295
 296         /* AM824 in IEC 61883-6 can deliver 24bit data. */
 297         return snd_pcm_hw_constraint_msbits(runtime, 0, 32, 24);
 298 }
 299 EXPORT_SYMBOL_GPL(amdtp_am824_add_pcm_hw_constraints);
 300
 301 /**
 302  * amdtp_am824_midi_trigger - start/stop playback/capture with a MIDI device
 303  * @s: the AMDTP stream
 304  * @port: index of MIDI port
 305  * @midi: the MIDI device to be started, or %NULL to stop the current device
 306  *
 307  * Call this function on a running isochronous stream to enable the actual
 308  * transmission of MIDI data.  This function should be called from the MIDI
 309  * device's .trigger callback.
 310  */
 311 void amdtp_am824_midi_trigger(struct amdtp_stream *s, unsigned int port,
 312                               struct snd_rawmidi_substream *midi)
 313 {
 314         struct amdtp_am824 *p = s->protocol;
 315
 316         if (port < p->midi_ports)
 317                 ACCESS_ONCE(p->midi[port]) = midi;
 318 }
 319 EXPORT_SYMBOL_GPL(amdtp_am824_midi_trigger);
 320
 321 /*
 322  * To avoid sending MIDI bytes at too high a rate, assume that the receiving
 323  * device has a FIFO, and track how much it is filled.  This values increases
 324  * by one whenever we send one byte in a packet, but the FIFO empties at
 325  * a constant rate independent of our packet rate.  One packet has syt_interval
 326  * samples, so the number of bytes that empty out of the FIFO, per packet(!),
 327  * is MIDI_BYTES_PER_SECOND * syt_interval / sample_rate.  To avoid storing
 328  * fractional values, the values in midi_fifo_used[] are measured in bytes
 329  * multiplied by the sample rate.
 330  */
 331 static bool midi_ratelimit_per_packet(struct amdtp_stream *s, unsigned int port)
 332 {
 333         struct amdtp_am824 *p = s->protocol;
 334         int used;
 335
 336         used = p->midi_fifo_used[port];
 337         if (used == 0) /* common shortcut */
 338                 return true;
 339
 340         used -= MIDI_BYTES_PER_SECOND * s->syt_interval;
 341         used = max(used, 0);
 342         p->midi_fifo_used[port] = used;
 343
 344         return used < p->midi_fifo_limit;
 345 }
 346
 347 static void midi_rate_use_one_byte(struct amdtp_stream *s, unsigned int port)
 348 {
 349         struct amdtp_am824 *p = s->protocol;
 350
 351         p->midi_fifo_used[port] += amdtp_rate_table[s->sfc];
 352 }
 353
 354 static void write_midi_messages(struct amdtp_stream *s, __be32 *buffer,
 355                                 unsigned int frames)
 356 {
 357         struct amdtp_am824 *p = s->protocol;
 358         unsigned int f, port;
 359         u8 *b;
 360
 361         for (f = 0; f < frames; f++) {
 362                 b = (u8 *)&buffer[p->midi_position];
 363
 364                 port = (s->data_block_counter + f) % 8;
 365                 if (f < MAX_MIDI_RX_BLOCKS &&
 366                     midi_ratelimit_per_packet(s, port) &&
 367                     p->midi[port] != NULL &&
 368                     snd_rawmidi_transmit(p->midi[port], &b[1], 1) == 1) {
 369                         midi_rate_use_one_byte(s, port);
 370                         b[0] = 0x81;
 371                 } else {
 372                         b[0] = 0x80;
 373                         b[1] = 0;
 374                 }
 375                 b[2] = 0;
 376                 b[3] = 0;
 377
 378                 buffer += s->data_block_quadlets;
 379         }
 380 }
 381
 382 static void read_midi_messages(struct amdtp_stream *s,
 383                                __be32 *buffer, unsigned int frames)
 384 {
 385         struct amdtp_am824 *p = s->protocol;
 386         unsigned int f, port;
 387         int len;
 388         u8 *b;
 389
 390         for (f = 0; f < frames; f++) {
 391                 port = (s->data_block_counter + f) % 8;
 392                 b = (u8 *)&buffer[p->midi_position];
 393
 394                 len = b[0] - 0x80;
 395                 if ((1 <= len) &&  (len <= 3) && (p->midi[port]))
 396                         snd_rawmidi_receive(p->midi[port], b + 1, len);
 397
 398                 buffer += s->data_block_quadlets;
 399         }
 400 }
 401
 402 static unsigned int process_rx_data_blocks(struct amdtp_stream *s, __be32 *buffer,
 403                                            unsigned int data_blocks, unsigned int *syt)
 404 {
 405         struct amdtp_am824 *p = s->protocol;
 406         struct snd_pcm_substream *pcm = ACCESS_ONCE(s->pcm);
 407         unsigned int pcm_frames;
 408
 409         if (pcm) {
 410                 p->transfer_samples(s, pcm, buffer, data_blocks);
 411                 pcm_frames = data_blocks * p->frame_multiplier;
 412         } else {
 413                 write_pcm_silence(s, buffer, data_blocks);
 414                 pcm_frames = 0;
 415         }
 416
 417         if (p->midi_ports)
 418                 write_midi_messages(s, buffer, data_blocks);
 419
 420         return pcm_frames;
 421 }
 422
 423 static unsigned int process_tx_data_blocks(struct amdtp_stream *s, __be32 *buffer,
 424                                            unsigned int data_blocks, unsigned int *syt)
 425 {
 426         struct amdtp_am824 *p = s->protocol;
 427         struct snd_pcm_substream *pcm = ACCESS_ONCE(s->pcm);
 428         unsigned int pcm_frames;
 429
 430         if (pcm) {
 431                 p->transfer_samples(s, pcm, buffer, data_blocks);
 432                 pcm_frames = data_blocks * p->frame_multiplier;
 433         } else {
 434                 pcm_frames = 0;
 435         }
 436
 437         if (p->midi_ports)
 438                 read_midi_messages(s, buffer, data_blocks);
 439
 440         return pcm_frames;
 441 }
 442
 443 /**
 444  * amdtp_am824_init - initialize an AMDTP stream structure to handle AM824
 445  *                    data block
 446  * @s: the AMDTP stream to initialize
 447  * @unit: the target of the stream
 448  * @dir: the direction of stream
 449  * @flags: the packet transmission method to use
 450  */
 451 int amdtp_am824_init(struct amdtp_stream *s, struct fw_unit *unit,
 452                      enum amdtp_stream_direction dir, enum cip_flags flags)
 453 {
 454         amdtp_stream_process_data_blocks_t process_data_blocks;
 455
 456         if (dir == AMDTP_IN_STREAM)
 457                 process_data_blocks = process_tx_data_blocks;
 458         else
 459                 process_data_blocks = process_rx_data_blocks;
 460
 461         return amdtp_stream_init(s, unit, dir, flags, CIP_FMT_AM,
 462                                  process_data_blocks,
 463                                  sizeof(struct amdtp_am824));
 464 }
 465 EXPORT_SYMBOL_GPL(amdtp_am824_init);