| // SPDX-License-Identifier: GPL-2.0-only |
| /* |
| * AM824 format in Audio and Music Data Transmission Protocol (IEC 61883-6) |
| * |
| * Copyright (c) Clemens Ladisch <clemens@ladisch.de> |
| * Copyright (c) 2015 Takashi Sakamoto <o-takashi@sakamocchi.jp> |
| */ |
| |
| #include <linux/slab.h> |
| |
| #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->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) |
| { |
| struct amdtp_am824 *p = s->protocol; |
| struct snd_pcm_runtime *runtime = pcm->runtime; |
| unsigned int channels, remaining_frames, i, c; |
| const u32 *src; |
| |
| channels = p->pcm_channels; |
| src = (void *)runtime->dma_area + |
| frames_to_bytes(runtime, s->pcm_buffer_pointer); |
| remaining_frames = runtime->buffer_size - s->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) |
| { |
| struct amdtp_am824 *p = s->protocol; |
| struct snd_pcm_runtime *runtime = pcm->runtime; |
| unsigned int channels, remaining_frames, i, c; |
| u32 *dst; |
| |
| channels = p->pcm_channels; |
| dst = (void *)runtime->dma_area + |
| frames_to_bytes(runtime, s->pcm_buffer_pointer); |
| remaining_frames = runtime->buffer_size - s->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) |
| { |
| 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 = (s->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) |
| { |
| struct amdtp_am824 *p = s->protocol; |
| unsigned int f, port; |
| int len; |
| u8 *b; |
| |
| for (f = 0; f < frames; f++) { |
| port = (s->data_block_counter + f) % 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, __be32 *buffer, |
| unsigned int data_blocks, unsigned int *syt) |
| { |
| struct amdtp_am824 *p = s->protocol; |
| struct snd_pcm_substream *pcm = READ_ONCE(s->pcm); |
| unsigned int pcm_frames; |
| |
| if (pcm) { |
| write_pcm_s32(s, pcm, buffer, data_blocks); |
| pcm_frames = data_blocks * p->frame_multiplier; |
| } else { |
| write_pcm_silence(s, buffer, data_blocks); |
| pcm_frames = 0; |
| } |
| |
| if (p->midi_ports) |
| write_midi_messages(s, buffer, data_blocks); |
| |
| return pcm_frames; |
| } |
| |
| static unsigned int process_tx_data_blocks(struct amdtp_stream *s, __be32 *buffer, |
| unsigned int data_blocks, unsigned int *syt) |
| { |
| struct amdtp_am824 *p = s->protocol; |
| struct snd_pcm_substream *pcm = READ_ONCE(s->pcm); |
| unsigned int pcm_frames; |
| |
| if (pcm) { |
| read_pcm_s32(s, pcm, buffer, data_blocks); |
| pcm_frames = data_blocks * p->frame_multiplier; |
| } else { |
| pcm_frames = 0; |
| } |
| |
| if (p->midi_ports) |
| read_midi_messages(s, buffer, data_blocks); |
| |
| 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); |