/*
 * amdtp-tascam.c - a part of driver for TASCAM FireWire series
 *
 * Copyright (c) 2015 Takashi Sakamoto
 *
 * Licensed under the terms of the GNU General Public License, version 2.
 */

#include <sound/pcm.h>
#include "tascam.h"

#define AMDTP_FMT_TSCM_TX       0x1e
#define AMDTP_FMT_TSCM_RX       0x3e

struct amdtp_tscm {
        unsigned int pcm_channels;
};

int amdtp_tscm_set_parameters(struct amdtp_stream *s, unsigned int rate)
{
        struct amdtp_tscm *p = s->protocol;
        unsigned int data_channels;

        if (amdtp_stream_running(s))
                return -EBUSY;

        data_channels = p->pcm_channels;

        /* Packets in in-stream have extra 2 data channels. */
        if (s->direction == AMDTP_IN_STREAM)
                data_channels += 2;

        return amdtp_stream_set_parameters(s, rate, data_channels);
}

static void write_pcm_s32(struct amdtp_stream *s,
                          struct snd_pcm_substream *pcm,
                          __be32 *buffer, unsigned int frames)
{
        struct amdtp_tscm *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[c] = cpu_to_be32(*src);
                        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_tscm *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;

        /* The first data channel is for event counter. */
        buffer += 1;

        for (i = 0; i < frames; ++i) {
                for (c = 0; c < channels; ++c) {
                        *dst = be32_to_cpu(buffer[c]);
                        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 data_blocks)
{
        struct amdtp_tscm *p = s->protocol;
        unsigned int channels, i, c;

        channels = p->pcm_channels;

        for (i = 0; i < data_blocks; ++i) {
                for (c = 0; c < channels; ++c)
                        buffer[c] = 0x00000000;
                buffer += s->data_block_quadlets;
        }
}

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

        /*
         * Our implementation allows this protocol to deliver 24 bit sample in
         * 32bit data channel.
         */
        err = snd_pcm_hw_constraint_msbits(runtime, 0, 32, 24);
        if (err < 0)
                return err;

        return amdtp_stream_add_pcm_hw_constraints(s, runtime);
}

static unsigned int process_tx_data_blocks(struct amdtp_stream *s,
                                           __be32 *buffer,
                                           unsigned int data_blocks,
                                           unsigned int *syt)
{
        struct snd_pcm_substream *pcm;

        pcm = ACCESS_ONCE(s->pcm);
        if (data_blocks > 0 && pcm)
                read_pcm_s32(s, pcm, buffer, data_blocks);

        /* A place holder for control messages. */

        return data_blocks;
}

static unsigned int process_rx_data_blocks(struct amdtp_stream *s,
                                           __be32 *buffer,
                                           unsigned int data_blocks,
                                           unsigned int *syt)
{
        struct snd_pcm_substream *pcm;

        /* This field is not used. */
        *syt = 0x0000;

        pcm = ACCESS_ONCE(s->pcm);
        if (pcm)
                write_pcm_s32(s, pcm, buffer, data_blocks);
        else
                write_pcm_silence(s, buffer, data_blocks);

        return data_blocks;
}

int amdtp_tscm_init(struct amdtp_stream *s, struct fw_unit *unit,
                    enum amdtp_stream_direction dir, unsigned int pcm_channels)
{
        amdtp_stream_process_data_blocks_t process_data_blocks;
        struct amdtp_tscm *p;
        unsigned int fmt;
        int err;

        if (dir == AMDTP_IN_STREAM) {
                fmt = AMDTP_FMT_TSCM_TX;
                process_data_blocks = process_tx_data_blocks;
        } else {
                fmt = AMDTP_FMT_TSCM_RX;
                process_data_blocks = process_rx_data_blocks;
        }

        err = amdtp_stream_init(s, unit, dir,
                                CIP_NONBLOCKING | CIP_SKIP_DBC_ZERO_CHECK, fmt,
                                process_data_blocks, sizeof(struct amdtp_tscm));
        if (err < 0)
                return 0;

        /* Use fixed value for FDF field. */
        s->fdf = 0x00;

        /* This protocol uses fixed number of data channels for PCM samples. */
        p = s->protocol;
        p->pcm_channels = pcm_channels;

        return 0;
}