// SPDX-License-Identifier: GPL-2.0-only
/*
 * amdtp-motu.c - a part of driver for MOTU FireWire series
 *
 * Copyright (c) 2015-2017 Takashi Sakamoto <o-takashi@sakamocchi.jp>
 */

#include <linux/slab.h>
#include <sound/pcm.h>
#include "motu.h"

#define CREATE_TRACE_POINTS
#include "amdtp-motu-trace.h"

#define CIP_FMT_MOTU            0x02
#define CIP_FMT_MOTU_TX_V3      0x22
#define MOTU_FDF_AM824          0x22

#define TICKS_PER_CYCLE         3072
#define CYCLES_PER_SECOND       8000
#define TICKS_PER_SECOND        (TICKS_PER_CYCLE * CYCLES_PER_SECOND)

#define CIP_SPH_CYCLE_SHIFT     12
#define CIP_SPH_CYCLE_MASK      0x01fff000
#define CIP_SPH_OFFSET_MASK     0x00000fff

/*
 * 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

struct amdtp_motu {
        unsigned int pcm_chunks;
        unsigned int pcm_byte_offset;

        struct snd_rawmidi_substream *midi;
        unsigned int midi_ports;
        unsigned int midi_flag_offset;
        unsigned int midi_byte_offset;

        int midi_db_count;
        unsigned int midi_db_interval;

        struct amdtp_motu_cache *cache;
};

int amdtp_motu_set_parameters(struct amdtp_stream *s, unsigned int rate,
                              unsigned int midi_ports,
                              struct snd_motu_packet_format *formats)
{
        struct amdtp_motu *p = s->protocol;
        unsigned int pcm_chunks, data_chunks, data_block_quadlets;
        unsigned int mode;
        int i, err;

        if (amdtp_stream_running(s))
                return -EBUSY;

        for (i = 0; i < ARRAY_SIZE(snd_motu_clock_rates); ++i) {
                if (snd_motu_clock_rates[i] == rate) {
                        mode = i >> 1;
                        break;
                }
        }
        if (i == ARRAY_SIZE(snd_motu_clock_rates))
                return -EINVAL;

        // Each data block includes SPH in its head. Data chunks follow with
        // 3 byte alignment. Padding follows with zero to conform to quadlet
        // alignment.
        pcm_chunks = formats->pcm_chunks[mode];
        data_chunks = formats->msg_chunks + pcm_chunks;
        data_block_quadlets = 1 + DIV_ROUND_UP(data_chunks * 3, 4);

        err = amdtp_stream_set_parameters(s, rate, data_block_quadlets);
        if (err < 0)
                return err;

        p->pcm_chunks = pcm_chunks;
        p->pcm_byte_offset = formats->pcm_byte_offset;

        p->midi_ports = midi_ports;
        p->midi_flag_offset = formats->midi_flag_offset;
        p->midi_byte_offset = formats->midi_byte_offset;

        p->midi_db_count = 0;
        p->midi_db_interval = rate / MIDI_BYTES_PER_SECOND;

        return 0;
}

static void read_pcm_s32(struct amdtp_stream *s, struct snd_pcm_substream *pcm,
                         __be32 *buffer, unsigned int data_blocks,
                         unsigned int pcm_frames)
{
        struct amdtp_motu *p = s->protocol;
        unsigned int channels = p->pcm_chunks;
        struct snd_pcm_runtime *runtime = pcm->runtime;
        unsigned int pcm_buffer_pointer;
        int remaining_frames;
        u8 *byte;
        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 < data_blocks; ++i) {
                byte = (u8 *)buffer + p->pcm_byte_offset;

                for (c = 0; c < channels; ++c) {
                        *dst = (byte[0] << 24) |
                               (byte[1] << 16) |
                               (byte[2] << 8);
                        byte += 3;
                        dst++;
                }
                buffer += s->data_block_quadlets;
                if (--remaining_frames == 0)
                        dst = (void *)runtime->dma_area;
        }
}

static void write_pcm_s32(struct amdtp_stream *s, struct snd_pcm_substream *pcm,
                          __be32 *buffer, unsigned int data_blocks,
                          unsigned int pcm_frames)
{
        struct amdtp_motu *p = s->protocol;
        unsigned int channels = p->pcm_chunks;
        struct snd_pcm_runtime *runtime = pcm->runtime;
        unsigned int pcm_buffer_pointer;
        int remaining_frames;
        u8 *byte;
        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 < data_blocks; ++i) {
                byte = (u8 *)buffer + p->pcm_byte_offset;

                for (c = 0; c < channels; ++c) {
                        byte[0] = (*src >> 24) & 0xff;
                        byte[1] = (*src >> 16) & 0xff;
                        byte[2] = (*src >>  8) & 0xff;
                        byte += 3;
                        src++;
                }

                buffer += s->data_block_quadlets;
                if (--remaining_frames == 0)
                        src = (void *)runtime->dma_area;
        }
}

static void write_pcm_silence(struct amdtp_stream *s, __be32 *buffer,
                              unsigned int data_blocks)
{
        struct amdtp_motu *p = s->protocol;
        unsigned int channels, i, c;
        u8 *byte;

        channels = p->pcm_chunks;

        for (i = 0; i < data_blocks; ++i) {
                byte = (u8 *)buffer + p->pcm_byte_offset;

                for (c = 0; c < channels; ++c) {
                        byte[0] = 0;
                        byte[1] = 0;
                        byte[2] = 0;
                        byte += 3;
                }

                buffer += s->data_block_quadlets;
        }
}

int amdtp_motu_add_pcm_hw_constraints(struct amdtp_stream *s,
                                      struct snd_pcm_runtime *runtime)
{
        int err;

        /* TODO: how to set an constraint for exactly 24bit PCM sample? */
        err = snd_pcm_hw_constraint_msbits(runtime, 0, 32, 24);
        if (err < 0)
                return err;

        return amdtp_stream_add_pcm_hw_constraints(s, runtime);
}

void amdtp_motu_midi_trigger(struct amdtp_stream *s, unsigned int port,
                             struct snd_rawmidi_substream *midi)
{
        struct amdtp_motu *p = s->protocol;

        if (port < p->midi_ports)
                WRITE_ONCE(p->midi, midi);
}

static void write_midi_messages(struct amdtp_stream *s, __be32 *buffer,
                                unsigned int data_blocks)
{
        struct amdtp_motu *p = s->protocol;
        struct snd_rawmidi_substream *midi = READ_ONCE(p->midi);
        u8 *b;
        int i;

        for (i = 0; i < data_blocks; i++) {
                b = (u8 *)buffer;

                if (midi && p->midi_db_count == 0 &&
                    snd_rawmidi_transmit(midi, b + p->midi_byte_offset, 1) == 1) {
                        b[p->midi_flag_offset] = 0x01;
                } else {
                        b[p->midi_byte_offset] = 0x00;
                        b[p->midi_flag_offset] = 0x00;
                }

                buffer += s->data_block_quadlets;

                if (--p->midi_db_count < 0)
                        p->midi_db_count = p->midi_db_interval;
        }
}

static void read_midi_messages(struct amdtp_stream *s, __be32 *buffer,
                               unsigned int data_blocks)
{
        struct amdtp_motu *p = s->protocol;
        struct snd_rawmidi_substream *midi;
        u8 *b;
        int i;

        for (i = 0; i < data_blocks; i++) {
                b = (u8 *)buffer;
                midi = READ_ONCE(p->midi);

                if (midi && (b[p->midi_flag_offset] & 0x01))
                        snd_rawmidi_receive(midi, b + p->midi_byte_offset, 1);

                buffer += s->data_block_quadlets;
        }
}

/* For tracepoints. */
static void __maybe_unused copy_sph(u32 *frames, __be32 *buffer,
                                    unsigned int data_blocks,
                                    unsigned int data_block_quadlets)
{
        unsigned int i;

        for (i = 0; i < data_blocks; ++i) {
                *frames = be32_to_cpu(*buffer);
                buffer += data_block_quadlets;
                frames++;
        }
}

/* For tracepoints. */
static void __maybe_unused copy_message(u64 *frames, __be32 *buffer,
                                        unsigned int data_blocks,
                                        unsigned int data_block_quadlets)
{
        unsigned int i;

        /* This is just for v2/v3 protocol. */
        for (i = 0; i < data_blocks; ++i) {
                *frames = be32_to_cpu(buffer[1]);
                *frames <<= 16;
                *frames |= be32_to_cpu(buffer[2]) >> 16;
                ++frames;
                buffer += data_block_quadlets;
        }
}

static void probe_tracepoints_events(struct amdtp_stream *s,
                                     const struct pkt_desc *descs,
                                     unsigned int packets)
{
        int i;

        for (i = 0; i < packets; ++i) {
                const struct pkt_desc *desc = descs + i;
                __be32 *buf = desc->ctx_payload;
                unsigned int data_blocks = desc->data_blocks;

                trace_data_block_sph(s, data_blocks, buf);
                trace_data_block_message(s, data_blocks, buf);
        }
}

static void cache_event_offsets(struct amdtp_motu_cache *cache, const __be32 *buf,
                                unsigned int data_blocks, unsigned int data_block_quadlets)
{
        unsigned int *event_offsets = cache->event_offsets;
        const unsigned int cache_size = cache->size;
        unsigned int cache_tail = cache->tail;
        unsigned int base_tick = cache->tx_cycle_count * TICKS_PER_CYCLE;
        int i;

        for (i = 0; i < data_blocks; ++i) {
                u32 sph = be32_to_cpu(*buf);
                unsigned int tick;

                tick = ((sph & CIP_SPH_CYCLE_MASK) >> CIP_SPH_CYCLE_SHIFT) * TICKS_PER_CYCLE +
                       (sph & CIP_SPH_OFFSET_MASK);

                if (tick < base_tick)
                        tick += TICKS_PER_SECOND;
                event_offsets[cache_tail] = tick - base_tick;

                cache_tail = (cache_tail + 1) % cache_size;
                buf += data_block_quadlets;
        }

        cache->tail = cache_tail;
        cache->tx_cycle_count = (cache->tx_cycle_count + 1) % CYCLES_PER_SECOND;
}

static unsigned int process_ir_ctx_payloads(struct amdtp_stream *s,
                                            const struct pkt_desc *descs,
                                            unsigned int packets,
                                            struct snd_pcm_substream *pcm)
{
        struct amdtp_motu *p = s->protocol;
        unsigned int pcm_frames = 0;
        int i;

        if (p->cache->tx_cycle_count == UINT_MAX)
                p->cache->tx_cycle_count = (s->domain->processing_cycle.tx_start % CYCLES_PER_SECOND);

        // For data block processing.
        for (i = 0; i < packets; ++i) {
                const struct pkt_desc *desc = descs + i;
                __be32 *buf = desc->ctx_payload;
                unsigned int data_blocks = desc->data_blocks;

                cache_event_offsets(p->cache, buf, data_blocks, s->data_block_quadlets);

                if (pcm) {
                        read_pcm_s32(s, pcm, buf, data_blocks, pcm_frames);
                        pcm_frames += data_blocks;
                }

                if (p->midi_ports)
                        read_midi_messages(s, buf, data_blocks);
        }

        // For tracepoints.
        if (trace_data_block_sph_enabled() ||
            trace_data_block_message_enabled())
                probe_tracepoints_events(s, descs, packets);

        return pcm_frames;
}

static void write_sph(struct amdtp_motu_cache *cache, __be32 *buffer, unsigned int data_blocks,
                      unsigned int data_block_quadlets)
{
        unsigned int *event_offsets = cache->event_offsets;
        const unsigned int cache_size = cache->size;
        unsigned int cache_head = cache->head;
        unsigned int base_tick = cache->rx_cycle_count * TICKS_PER_CYCLE;
        int i;

        for (i = 0; i < data_blocks; i++) {
                unsigned int tick = (base_tick + event_offsets[cache_head]) % TICKS_PER_SECOND;
                u32 sph = ((tick / TICKS_PER_CYCLE) << CIP_SPH_CYCLE_SHIFT) | (tick % TICKS_PER_CYCLE);
                *buffer = cpu_to_be32(sph);

                cache_head = (cache_head + 1) % cache_size;
                buffer += data_block_quadlets;
        }

        cache->head = cache_head;
        cache->rx_cycle_count = (cache->rx_cycle_count + 1) % CYCLES_PER_SECOND;
}

static unsigned int process_it_ctx_payloads(struct amdtp_stream *s,
                                            const struct pkt_desc *descs,
                                            unsigned int packets,
                                            struct snd_pcm_substream *pcm)
{
        struct amdtp_motu *p = s->protocol;
        unsigned int pcm_frames = 0;
        int i;

        if (p->cache->rx_cycle_count == UINT_MAX)
                p->cache->rx_cycle_count = (s->domain->processing_cycle.rx_start % CYCLES_PER_SECOND);

        // For data block processing.
        for (i = 0; i < packets; ++i) {
                const struct pkt_desc *desc = descs + i;
                __be32 *buf = desc->ctx_payload;
                unsigned int data_blocks = desc->data_blocks;

                if (pcm) {
                        write_pcm_s32(s, pcm, buf, data_blocks, pcm_frames);
                        pcm_frames += data_blocks;
                } else {
                        write_pcm_silence(s, buf, data_blocks);
                }

                if (p->midi_ports)
                        write_midi_messages(s, buf, data_blocks);

                // TODO: how to interact control messages between userspace?

                write_sph(p->cache, buf, data_blocks, s->data_block_quadlets);
        }

        // For tracepoints.
        if (trace_data_block_sph_enabled() ||
            trace_data_block_message_enabled())
                probe_tracepoints_events(s, descs, packets);

        return pcm_frames;
}

int amdtp_motu_init(struct amdtp_stream *s, struct fw_unit *unit,
                    enum amdtp_stream_direction dir,
                    const struct snd_motu_spec *spec, struct amdtp_motu_cache *cache)
{
        amdtp_stream_process_ctx_payloads_t process_ctx_payloads;
        int fmt = CIP_FMT_MOTU;
        unsigned int flags = CIP_BLOCKING | CIP_UNAWARE_SYT;
        struct amdtp_motu *p;
        int err;

        if (dir == AMDTP_IN_STREAM) {
                process_ctx_payloads = process_ir_ctx_payloads;

                /*
                 * Units of version 3 transmits packets with invalid CIP header
                 * against IEC 61883-1.
                 */
                if (spec->protocol_version == SND_MOTU_PROTOCOL_V3) {
                        flags |= CIP_WRONG_DBS |
                                 CIP_SKIP_DBC_ZERO_CHECK |
                                 CIP_HEADER_WITHOUT_EOH;
                        fmt = CIP_FMT_MOTU_TX_V3;
                }

                if (spec == &snd_motu_spec_8pre ||
                    spec == &snd_motu_spec_ultralite) {
                        // 8pre has some quirks.
                        flags |= CIP_WRONG_DBS |
                                 CIP_SKIP_DBC_ZERO_CHECK;
                }
        } else {
                process_ctx_payloads = process_it_ctx_payloads;
                flags |= CIP_DBC_IS_END_EVENT;
        }

        err = amdtp_stream_init(s, unit, dir, flags, fmt, process_ctx_payloads,
                                sizeof(struct amdtp_motu));
        if (err < 0)
                return err;

        s->sph = 1;

        if (dir == AMDTP_OUT_STREAM) {
                // Use fixed value for FDF field.
                s->ctx_data.rx.fdf = MOTU_FDF_AM824;
        }

        p = s->protocol;
        p->cache = cache;

        return 0;
}