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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * AM824 format in Audio and Music Data Transmission Protocol (IEC 61883-6)4 *5 * Copyright (c) Clemens Ladisch <clemens@ladisch.de>6 * Copyright (c) 2015 Takashi Sakamoto <o-takashi@sakamocchi.jp>7 */8 9#include <linux/slab.h>10 11#include "amdtp-am824.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 30struct amdtp_am824 {31 struct snd_rawmidi_substream *midi[AM824_MAX_CHANNELS_FOR_MIDI * 8];32 int midi_fifo_limit;33 int midi_fifo_used[AM824_MAX_CHANNELS_FOR_MIDI * 8];34 unsigned int pcm_channels;35 unsigned int midi_ports;36 37 u8 pcm_positions[AM824_MAX_CHANNELS_FOR_PCM];38 u8 midi_position;39};40 41/**42 * amdtp_am824_set_parameters - set stream parameters43 * @s: the AMDTP stream to configure44 * @rate: the sample rate45 * @pcm_channels: the number of PCM samples in each data block, to be encoded46 * as AM824 multi-bit linear audio47 * @midi_ports: the number of MIDI ports (i.e., MPX-MIDI Data Channels)48 * @double_pcm_frames: one data block transfers two PCM frames49 *50 * The parameters must be set before the stream is started, and must not be51 * changed while the stream is running.52 */53int amdtp_am824_set_parameters(struct amdtp_stream *s, unsigned int rate,54 unsigned int pcm_channels,55 unsigned int midi_ports,56 bool double_pcm_frames)57{58 struct amdtp_am824 *p = s->protocol;59 unsigned int midi_channels;60 unsigned int pcm_frame_multiplier;61 int i, err;62 63 if (amdtp_stream_running(s))64 return -EINVAL;65 66 if (pcm_channels > AM824_MAX_CHANNELS_FOR_PCM)67 return -EINVAL;68 69 midi_channels = DIV_ROUND_UP(midi_ports, 8);70 if (midi_channels > AM824_MAX_CHANNELS_FOR_MIDI)71 return -EINVAL;72 73 if (WARN_ON(amdtp_stream_running(s)) ||74 WARN_ON(pcm_channels > AM824_MAX_CHANNELS_FOR_PCM) ||75 WARN_ON(midi_channels > AM824_MAX_CHANNELS_FOR_MIDI))76 return -EINVAL;77 78 /*79 * In IEC 61883-6, one data block represents one event. In ALSA, one80 * event equals to one PCM frame. But Dice has a quirk at higher81 * sampling rate to transfer two PCM frames in one data block.82 */83 if (double_pcm_frames)84 pcm_frame_multiplier = 2;85 else86 pcm_frame_multiplier = 1;87 88 err = amdtp_stream_set_parameters(s, rate, pcm_channels + midi_channels,89 pcm_frame_multiplier);90 if (err < 0)91 return err;92 93 if (s->direction == AMDTP_OUT_STREAM)94 s->ctx_data.rx.fdf = AMDTP_FDF_AM824 | s->sfc;95 96 p->pcm_channels = pcm_channels;97 p->midi_ports = midi_ports;98 99 /* init the position map for PCM and MIDI channels */100 for (i = 0; i < pcm_channels; i++)101 p->pcm_positions[i] = i;102 p->midi_position = p->pcm_channels;103 104 /*105 * We do not know the actual MIDI FIFO size of most devices. Just106 * assume two bytes, i.e., one byte can be received over the bus while107 * the previous one is transmitted over MIDI.108 * (The value here is adjusted for midi_ratelimit_per_packet().)109 */110 p->midi_fifo_limit = rate - MIDI_BYTES_PER_SECOND * s->syt_interval + 1;111 112 return 0;113}114EXPORT_SYMBOL_GPL(amdtp_am824_set_parameters);115 116/**117 * amdtp_am824_set_pcm_position - set an index of data channel for a channel118 * of PCM frame119 * @s: the AMDTP stream120 * @index: the index of data channel in an data block121 * @position: the channel of PCM frame122 */123void amdtp_am824_set_pcm_position(struct amdtp_stream *s, unsigned int index,124 unsigned int position)125{126 struct amdtp_am824 *p = s->protocol;127 128 if (index < p->pcm_channels)129 p->pcm_positions[index] = position;130}131EXPORT_SYMBOL_GPL(amdtp_am824_set_pcm_position);132 133/**134 * amdtp_am824_set_midi_position - set a index of data channel for MIDI135 * conformant data channel136 * @s: the AMDTP stream137 * @position: the index of data channel in an data block138 */139void amdtp_am824_set_midi_position(struct amdtp_stream *s,140 unsigned int position)141{142 struct amdtp_am824 *p = s->protocol;143 144 p->midi_position = position;145}146EXPORT_SYMBOL_GPL(amdtp_am824_set_midi_position);147 148static void write_pcm_s32(struct amdtp_stream *s, struct snd_pcm_substream *pcm,149 __be32 *buffer, unsigned int frames,150 unsigned int pcm_frames)151{152 struct amdtp_am824 *p = s->protocol;153 unsigned int channels = p->pcm_channels;154 struct snd_pcm_runtime *runtime = pcm->runtime;155 unsigned int pcm_buffer_pointer;156 int remaining_frames;157 const u32 *src;158 int i, c;159 160 pcm_buffer_pointer = s->pcm_buffer_pointer + pcm_frames;161 pcm_buffer_pointer %= runtime->buffer_size;162 163 src = (void *)runtime->dma_area +164 frames_to_bytes(runtime, pcm_buffer_pointer);165 remaining_frames = runtime->buffer_size - pcm_buffer_pointer;166 167 for (i = 0; i < frames; ++i) {168 for (c = 0; c < channels; ++c) {169 buffer[p->pcm_positions[c]] =170 cpu_to_be32((*src >> 8) | 0x40000000);171 src++;172 }173 buffer += s->data_block_quadlets;174 if (--remaining_frames == 0)175 src = (void *)runtime->dma_area;176 }177}178 179static void read_pcm_s32(struct amdtp_stream *s, struct snd_pcm_substream *pcm,180 __be32 *buffer, unsigned int frames,181 unsigned int pcm_frames)182{183 struct amdtp_am824 *p = s->protocol;184 unsigned int channels = p->pcm_channels;185 struct snd_pcm_runtime *runtime = pcm->runtime;186 unsigned int pcm_buffer_pointer;187 int remaining_frames;188 u32 *dst;189 int i, c;190 191 pcm_buffer_pointer = s->pcm_buffer_pointer + pcm_frames;192 pcm_buffer_pointer %= runtime->buffer_size;193 194 dst = (void *)runtime->dma_area +195 frames_to_bytes(runtime, pcm_buffer_pointer);196 remaining_frames = runtime->buffer_size - pcm_buffer_pointer;197 198 for (i = 0; i < frames; ++i) {199 for (c = 0; c < channels; ++c) {200 *dst = be32_to_cpu(buffer[p->pcm_positions[c]]) << 8;201 dst++;202 }203 buffer += s->data_block_quadlets;204 if (--remaining_frames == 0)205 dst = (void *)runtime->dma_area;206 }207}208 209static void write_pcm_silence(struct amdtp_stream *s,210 __be32 *buffer, unsigned int frames)211{212 struct amdtp_am824 *p = s->protocol;213 unsigned int i, c, channels = p->pcm_channels;214 215 for (i = 0; i < frames; ++i) {216 for (c = 0; c < channels; ++c)217 buffer[p->pcm_positions[c]] = cpu_to_be32(0x40000000);218 buffer += s->data_block_quadlets;219 }220}221 222/**223 * amdtp_am824_add_pcm_hw_constraints - add hw constraints for PCM substream224 * @s: the AMDTP stream for AM824 data block, must be initialized.225 * @runtime: the PCM substream runtime226 *227 */228int amdtp_am824_add_pcm_hw_constraints(struct amdtp_stream *s,229 struct snd_pcm_runtime *runtime)230{231 int err;232 233 err = amdtp_stream_add_pcm_hw_constraints(s, runtime);234 if (err < 0)235 return err;236 237 /* AM824 in IEC 61883-6 can deliver 24bit data. */238 return snd_pcm_hw_constraint_msbits(runtime, 0, 32, 24);239}240EXPORT_SYMBOL_GPL(amdtp_am824_add_pcm_hw_constraints);241 242/**243 * amdtp_am824_midi_trigger - start/stop playback/capture with a MIDI device244 * @s: the AMDTP stream245 * @port: index of MIDI port246 * @midi: the MIDI device to be started, or %NULL to stop the current device247 *248 * Call this function on a running isochronous stream to enable the actual249 * transmission of MIDI data. This function should be called from the MIDI250 * device's .trigger callback.251 */252void amdtp_am824_midi_trigger(struct amdtp_stream *s, unsigned int port,253 struct snd_rawmidi_substream *midi)254{255 struct amdtp_am824 *p = s->protocol;256 257 if (port < p->midi_ports)258 WRITE_ONCE(p->midi[port], midi);259}260EXPORT_SYMBOL_GPL(amdtp_am824_midi_trigger);261 262/*263 * To avoid sending MIDI bytes at too high a rate, assume that the receiving264 * device has a FIFO, and track how much it is filled. This values increases265 * by one whenever we send one byte in a packet, but the FIFO empties at266 * a constant rate independent of our packet rate. One packet has syt_interval267 * samples, so the number of bytes that empty out of the FIFO, per packet(!),268 * is MIDI_BYTES_PER_SECOND * syt_interval / sample_rate. To avoid storing269 * fractional values, the values in midi_fifo_used[] are measured in bytes270 * multiplied by the sample rate.271 */272static bool midi_ratelimit_per_packet(struct amdtp_stream *s, unsigned int port)273{274 struct amdtp_am824 *p = s->protocol;275 int used;276 277 used = p->midi_fifo_used[port];278 if (used == 0) /* common shortcut */279 return true;280 281 used -= MIDI_BYTES_PER_SECOND * s->syt_interval;282 used = max(used, 0);283 p->midi_fifo_used[port] = used;284 285 return used < p->midi_fifo_limit;286}287 288static void midi_rate_use_one_byte(struct amdtp_stream *s, unsigned int port)289{290 struct amdtp_am824 *p = s->protocol;291 292 p->midi_fifo_used[port] += amdtp_rate_table[s->sfc];293}294 295static void write_midi_messages(struct amdtp_stream *s, __be32 *buffer,296 unsigned int frames, unsigned int data_block_counter)297{298 struct amdtp_am824 *p = s->protocol;299 unsigned int f, port;300 u8 *b;301 302 for (f = 0; f < frames; f++) {303 b = (u8 *)&buffer[p->midi_position];304 305 port = (data_block_counter + f) % 8;306 if (f < MAX_MIDI_RX_BLOCKS &&307 midi_ratelimit_per_packet(s, port) &&308 p->midi[port] != NULL &&309 snd_rawmidi_transmit(p->midi[port], &b[1], 1) == 1) {310 midi_rate_use_one_byte(s, port);311 b[0] = 0x81;312 } else {313 b[0] = 0x80;314 b[1] = 0;315 }316 b[2] = 0;317 b[3] = 0;318 319 buffer += s->data_block_quadlets;320 }321}322 323static void read_midi_messages(struct amdtp_stream *s, __be32 *buffer,324 unsigned int frames, unsigned int data_block_counter)325{326 struct amdtp_am824 *p = s->protocol;327 int len;328 u8 *b;329 int f;330 331 for (f = 0; f < frames; f++) {332 unsigned int port = f;333 334 if (!(s->flags & CIP_UNALIGHED_DBC))335 port += data_block_counter;336 port %= 8;337 b = (u8 *)&buffer[p->midi_position];338 339 len = b[0] - 0x80;340 if ((1 <= len) && (len <= 3) && (p->midi[port]))341 snd_rawmidi_receive(p->midi[port], b + 1, len);342 343 buffer += s->data_block_quadlets;344 }345}346 347static void process_it_ctx_payloads(struct amdtp_stream *s, const struct pkt_desc *desc,348 unsigned int count, struct snd_pcm_substream *pcm)349{350 struct amdtp_am824 *p = s->protocol;351 unsigned int pcm_frames = 0;352 int i;353 354 for (i = 0; i < count; ++i) {355 __be32 *buf = desc->ctx_payload;356 unsigned int data_blocks = desc->data_blocks;357 358 if (pcm) {359 write_pcm_s32(s, pcm, buf, data_blocks, pcm_frames);360 pcm_frames += data_blocks * s->pcm_frame_multiplier;361 } else {362 write_pcm_silence(s, buf, data_blocks);363 }364 365 if (p->midi_ports) {366 write_midi_messages(s, buf, data_blocks,367 desc->data_block_counter);368 }369 370 desc = amdtp_stream_next_packet_desc(s, desc);371 }372}373 374static void process_ir_ctx_payloads(struct amdtp_stream *s, const struct pkt_desc *desc,375 unsigned int count, struct snd_pcm_substream *pcm)376{377 struct amdtp_am824 *p = s->protocol;378 unsigned int pcm_frames = 0;379 int i;380 381 for (i = 0; i < count; ++i) {382 __be32 *buf = desc->ctx_payload;383 unsigned int data_blocks = desc->data_blocks;384 385 if (pcm) {386 read_pcm_s32(s, pcm, buf, data_blocks, pcm_frames);387 pcm_frames += data_blocks * s->pcm_frame_multiplier;388 }389 390 if (p->midi_ports) {391 read_midi_messages(s, buf, data_blocks,392 desc->data_block_counter);393 }394 395 desc = amdtp_stream_next_packet_desc(s, desc);396 }397}398 399/**400 * amdtp_am824_init - initialize an AMDTP stream structure to handle AM824401 * data block402 * @s: the AMDTP stream to initialize403 * @unit: the target of the stream404 * @dir: the direction of stream405 * @flags: the details of the streaming protocol consist of cip_flags enumeration-constants.406 */407int amdtp_am824_init(struct amdtp_stream *s, struct fw_unit *unit,408 enum amdtp_stream_direction dir, unsigned int flags)409{410 amdtp_stream_process_ctx_payloads_t process_ctx_payloads;411 412 if (dir == AMDTP_IN_STREAM)413 process_ctx_payloads = process_ir_ctx_payloads;414 else415 process_ctx_payloads = process_it_ctx_payloads;416 417 return amdtp_stream_init(s, unit, dir, flags, CIP_FMT_AM,418 process_ctx_payloads, sizeof(struct amdtp_am824));419}420EXPORT_SYMBOL_GPL(amdtp_am824_init);421