// SPDX-License-Identifier: GPL-2.0-only /* * AM824 format in Audio and Music Data Transmission Protocol (IEC 61883-6) * * Copyright (c) Clemens Ladisch * Copyright (c) 2015 Takashi Sakamoto */ #include #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; 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->ctx_data.rx.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, unsigned int pcm_frames) { struct amdtp_am824 *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; 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 read_pcm_s32(struct amdtp_stream *s, struct snd_pcm_substream *pcm, __be32 *buffer, unsigned int frames, unsigned int pcm_frames) { struct amdtp_am824 *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; 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_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) WRITE_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, unsigned int data_block_counter) { 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 = (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, unsigned int data_block_counter) { struct amdtp_am824 *p = s->protocol; int len; u8 *b; int f; for (f = 0; f < frames; f++) { unsigned int port = f; if (!(s->flags & CIP_UNALIGHED_DBC)) port += data_block_counter; port %= 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, const struct pkt_desc *desc, struct snd_pcm_substream *pcm) { struct amdtp_am824 *p = s->protocol; unsigned int pcm_frames = 0; if (pcm) { write_pcm_s32(s, pcm, desc->ctx_payload, desc->data_blocks, pcm_frames); pcm_frames = desc->data_blocks * p->frame_multiplier; } else { write_pcm_silence(s, desc->ctx_payload, desc->data_blocks); } if (p->midi_ports) { write_midi_messages(s, desc->ctx_payload, desc->data_blocks, desc->data_block_counter); } return pcm_frames; } static unsigned int process_tx_data_blocks(struct amdtp_stream *s, const struct pkt_desc *desc, struct snd_pcm_substream *pcm) { struct amdtp_am824 *p = s->protocol; unsigned int pcm_frames = 0; if (pcm) { read_pcm_s32(s, pcm, desc->ctx_payload, desc->data_blocks, pcm_frames); pcm_frames = desc->data_blocks * p->frame_multiplier; } if (p->midi_ports) { read_midi_messages(s, desc->ctx_payload, desc->data_blocks, desc->data_block_counter); } 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);