// SPDX-License-Identifier: GPL-2.0-only /* * AM824 format in Audio and Music Data Transmission Protocol (IEC 61883-6) * * Copyright (c) Clemens Ladisch <[email protected]> * Copyright (c) 2015 Takashi Sakamoto <[email protected]> */ #include <linux/slab.h> #include "amdtp-am824.h" #define CIP_FMT_AM … /* "Clock-based rate control mode" is just supported. */ #define AMDTP_FDF_AM824 … /* * 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 … /* * 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 … struct amdtp_am824 { … }; /** * 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) { … } EXPORT_SYMBOL_GPL(…); /** * 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) { … } EXPORT_SYMBOL_GPL(…); /** * 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) { … } EXPORT_SYMBOL_GPL(…); static void write_pcm_s32(struct amdtp_stream *s, struct snd_pcm_substream *pcm, __be32 *buffer, unsigned int frames, unsigned int pcm_frames) { … } static void read_pcm_s32(struct amdtp_stream *s, struct snd_pcm_substream *pcm, __be32 *buffer, unsigned int frames, unsigned int pcm_frames) { … } static void write_pcm_silence(struct amdtp_stream *s, __be32 *buffer, unsigned int frames) { … } /** * 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) { … } EXPORT_SYMBOL_GPL(…); /** * 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) { … } EXPORT_SYMBOL_GPL(…); /* * 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) { … } static void midi_rate_use_one_byte(struct amdtp_stream *s, unsigned int port) { … } static void write_midi_messages(struct amdtp_stream *s, __be32 *buffer, unsigned int frames, unsigned int data_block_counter) { … } static void read_midi_messages(struct amdtp_stream *s, __be32 *buffer, unsigned int frames, unsigned int data_block_counter) { … } static void process_it_ctx_payloads(struct amdtp_stream *s, const struct pkt_desc *desc, unsigned int count, struct snd_pcm_substream *pcm) { … } static void process_ir_ctx_payloads(struct amdtp_stream *s, const struct pkt_desc *desc, unsigned int count, struct snd_pcm_substream *pcm) { … } /** * 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 details of the streaming protocol consist of cip_flags enumeration-constants. */ int amdtp_am824_init(struct amdtp_stream *s, struct fw_unit *unit, enum amdtp_stream_direction dir, unsigned int flags) { … } EXPORT_SYMBOL_GPL(…);
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