/*
 * Audio and Music Data Transmission Protocol (IEC 61883-6) streams
 * with Common Isochronous Packet (IEC 61883-1) headers
 *
 * Copyright (c) Clemens Ladisch <clemens@ladisch.de>
 * Licensed under the terms of the GNU General Public License, version 2.
 */

#include <linux/device.h>
#include <linux/err.h>
#include <linux/firewire.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <sound/pcm.h>
#include "amdtp.h"

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

#define TRANSFER_DELAY_TICKS    0x2e00 /* 479.17 µs */

#define TAG_CIP                 1

#define CIP_EOH                 (1u << 31)
#define CIP_FMT_AM              (0x10 << 24)
#define AMDTP_FDF_AM824         (0 << 19)
#define AMDTP_FDF_SFC_SHIFT     16

/* TODO: make these configurable */
#define INTERRUPT_INTERVAL      16
#define QUEUE_LENGTH            48

static void pcm_period_tasklet(unsigned long data);

/**
 * amdtp_out_stream_init - initialize an AMDTP output stream structure
 * @s: the AMDTP output stream to initialize
 * @unit: the target of the stream
 * @flags: the packet transmission method to use
 */
int amdtp_out_stream_init(struct amdtp_out_stream *s, struct fw_unit *unit,
                          enum cip_out_flags flags)
{
        if (flags != CIP_NONBLOCKING)
                return -EINVAL;

        s->unit = fw_unit_get(unit);
        s->flags = flags;
        s->context = ERR_PTR(-1);
        mutex_init(&s->mutex);
        tasklet_init(&s->period_tasklet, pcm_period_tasklet, (unsigned long)s);
        s->packet_index = 0;

        return 0;
}
EXPORT_SYMBOL(amdtp_out_stream_init);

/**
 * amdtp_out_stream_destroy - free stream resources
 * @s: the AMDTP output stream to destroy
 */
void amdtp_out_stream_destroy(struct amdtp_out_stream *s)
{
        WARN_ON(!IS_ERR(s->context));
        mutex_destroy(&s->mutex);
        fw_unit_put(s->unit);
}
EXPORT_SYMBOL(amdtp_out_stream_destroy);

/**
 * amdtp_out_stream_set_rate - set the sample rate
 * @s: the AMDTP output stream to configure
 * @rate: the sample rate
 *
 * The sample rate must be set before the stream is started, and must not be
 * changed while the stream is running.
 */
void amdtp_out_stream_set_rate(struct amdtp_out_stream *s, unsigned int rate)
{
        static const struct {
                unsigned int rate;
                unsigned int syt_interval;
        } rate_info[] = {
                [CIP_SFC_32000]  = {  32000,  8, },
                [CIP_SFC_44100]  = {  44100,  8, },
                [CIP_SFC_48000]  = {  48000,  8, },
                [CIP_SFC_88200]  = {  88200, 16, },
                [CIP_SFC_96000]  = {  96000, 16, },
                [CIP_SFC_176400] = { 176400, 32, },
                [CIP_SFC_192000] = { 192000, 32, },
        };
        unsigned int sfc;

        if (WARN_ON(!IS_ERR(s->context)))
                return;

        for (sfc = 0; sfc < ARRAY_SIZE(rate_info); ++sfc)
                if (rate_info[sfc].rate == rate) {
                        s->sfc = sfc;
                        s->syt_interval = rate_info[sfc].syt_interval;
                        return;
                }
        WARN_ON(1);
}
EXPORT_SYMBOL(amdtp_out_stream_set_rate);

/**
 * amdtp_out_stream_get_max_payload - get the stream's packet size
 * @s: the AMDTP output stream
 *
 * This function must not be called before the stream has been configured
 * with amdtp_out_stream_set_hw_params(), amdtp_out_stream_set_pcm(), and
 * amdtp_out_stream_set_midi().
 */
unsigned int amdtp_out_stream_get_max_payload(struct amdtp_out_stream *s)
{
        static const unsigned int max_data_blocks[] = {
                [CIP_SFC_32000]  =  4,
                [CIP_SFC_44100]  =  6,
                [CIP_SFC_48000]  =  6,
                [CIP_SFC_88200]  = 12,
                [CIP_SFC_96000]  = 12,
                [CIP_SFC_176400] = 23,
                [CIP_SFC_192000] = 24,
        };

        s->data_block_quadlets = s->pcm_channels;
        s->data_block_quadlets += DIV_ROUND_UP(s->midi_ports, 8);

        return 8 + max_data_blocks[s->sfc] * 4 * s->data_block_quadlets;
}
EXPORT_SYMBOL(amdtp_out_stream_get_max_payload);

static void amdtp_write_s16(struct amdtp_out_stream *s,
                            struct snd_pcm_substream *pcm,
                            __be32 *buffer, unsigned int frames);
static void amdtp_write_s32(struct amdtp_out_stream *s,
                            struct snd_pcm_substream *pcm,
                            __be32 *buffer, unsigned int frames);

/**
 * amdtp_out_stream_set_pcm_format - set the PCM format
 * @s: the AMDTP output stream to configure
 * @format: the format of the ALSA PCM device
 *
 * The sample format must be set before the stream is started, and must not be
 * changed while the stream is running.
 */
void amdtp_out_stream_set_pcm_format(struct amdtp_out_stream *s,
                                     snd_pcm_format_t format)
{
        if (WARN_ON(!IS_ERR(s->context)))
                return;

        switch (format) {
        default:
                WARN_ON(1);
                /* fall through */
        case SNDRV_PCM_FORMAT_S16:
                s->transfer_samples = amdtp_write_s16;
                break;
        case SNDRV_PCM_FORMAT_S32:
                s->transfer_samples = amdtp_write_s32;
                break;
        }
}
EXPORT_SYMBOL(amdtp_out_stream_set_pcm_format);

/**
 * amdtp_out_stream_pcm_prepare - prepare PCM device for running
 * @s: the AMDTP output stream
 *
 * This function should be called from the PCM device's .prepare callback.
 */
void amdtp_out_stream_pcm_prepare(struct amdtp_out_stream *s)
{
        tasklet_kill(&s->period_tasklet);
        s->pcm_buffer_pointer = 0;
        s->pcm_period_pointer = 0;
        s->pointer_flush = true;
}
EXPORT_SYMBOL(amdtp_out_stream_pcm_prepare);

static unsigned int calculate_data_blocks(struct amdtp_out_stream *s)
{
        unsigned int phase, data_blocks;

        if (!cip_sfc_is_base_44100(s->sfc)) {
                /* Sample_rate / 8000 is an integer, and precomputed. */
                data_blocks = s->data_block_state;
        } else {
                phase = s->data_block_state;

                /*
                 * This calculates the number of data blocks per packet so that
                 * 1) the overall rate is correct and exactly synchronized to
                 *    the bus clock, and
                 * 2) packets with a rounded-up number of blocks occur as early
                 *    as possible in the sequence (to prevent underruns of the
                 *    device's buffer).
                 */
                if (s->sfc == CIP_SFC_44100)
                        /* 6 6 5 6 5 6 5 ... */
                        data_blocks = 5 + ((phase & 1) ^
                                           (phase == 0 || phase >= 40));
                else
                        /* 12 11 11 11 11 ... or 23 22 22 22 22 ... */
                        data_blocks = 11 * (s->sfc >> 1) + (phase == 0);
                if (++phase >= (80 >> (s->sfc >> 1)))
                        phase = 0;
                s->data_block_state = phase;
        }

        return data_blocks;
}

static unsigned int calculate_syt(struct amdtp_out_stream *s,
                                  unsigned int cycle)
{
        unsigned int syt_offset, phase, index, syt;

        if (s->last_syt_offset < TICKS_PER_CYCLE) {
                if (!cip_sfc_is_base_44100(s->sfc))
                        syt_offset = s->last_syt_offset + s->syt_offset_state;
                else {
                /*
                 * The time, in ticks, of the n'th SYT_INTERVAL sample is:
                 *   n * SYT_INTERVAL * 24576000 / sample_rate
                 * Modulo TICKS_PER_CYCLE, the difference between successive
                 * elements is about 1386.23.  Rounding the results of this
                 * formula to the SYT precision results in a sequence of
                 * differences that begins with:
                 *   1386 1386 1387 1386 1386 1386 1387 1386 1386 1386 1387 ...
                 * This code generates _exactly_ the same sequence.
                 */
                        phase = s->syt_offset_state;
                        index = phase % 13;
                        syt_offset = s->last_syt_offset;
                        syt_offset += 1386 + ((index && !(index & 3)) ||
                                              phase == 146);
                        if (++phase >= 147)
                                phase = 0;
                        s->syt_offset_state = phase;
                }
        } else
                syt_offset = s->last_syt_offset - TICKS_PER_CYCLE;
        s->last_syt_offset = syt_offset;

        if (syt_offset < TICKS_PER_CYCLE) {
                syt_offset += TRANSFER_DELAY_TICKS - TICKS_PER_CYCLE;
                syt = (cycle + syt_offset / TICKS_PER_CYCLE) << 12;
                syt += syt_offset % TICKS_PER_CYCLE;

                return syt & 0xffff;
        } else {
                return 0xffff; /* no info */
        }
}

static void amdtp_write_s32(struct amdtp_out_stream *s,
                            struct snd_pcm_substream *pcm,
                            __be32 *buffer, unsigned int frames)
{
        struct snd_pcm_runtime *runtime = pcm->runtime;
        unsigned int channels, remaining_frames, frame_step, i, c;
        const u32 *src;

        channels = s->pcm_channels;
        src = (void *)runtime->dma_area +
                        s->pcm_buffer_pointer * (runtime->frame_bits / 8);
        remaining_frames = runtime->buffer_size - s->pcm_buffer_pointer;
        frame_step = s->data_block_quadlets - channels;

        for (i = 0; i < frames; ++i) {
                for (c = 0; c < channels; ++c) {
                        *buffer = cpu_to_be32((*src >> 8) | 0x40000000);
                        src++;
                        buffer++;
                }
                buffer += frame_step;
                if (--remaining_frames == 0)
                        src = (void *)runtime->dma_area;
        }
}

static void amdtp_write_s16(struct amdtp_out_stream *s,
                            struct snd_pcm_substream *pcm,
                            __be32 *buffer, unsigned int frames)
{
        struct snd_pcm_runtime *runtime = pcm->runtime;
        unsigned int channels, remaining_frames, frame_step, i, c;
        const u16 *src;

        channels = s->pcm_channels;
        src = (void *)runtime->dma_area +
                        s->pcm_buffer_pointer * (runtime->frame_bits / 8);
        remaining_frames = runtime->buffer_size - s->pcm_buffer_pointer;
        frame_step = s->data_block_quadlets - channels;

        for (i = 0; i < frames; ++i) {
                for (c = 0; c < channels; ++c) {
                        *buffer = cpu_to_be32((*src << 8) | 0x40000000);
                        src++;
                        buffer++;
                }
                buffer += frame_step;
                if (--remaining_frames == 0)
                        src = (void *)runtime->dma_area;
        }
}

static void amdtp_fill_pcm_silence(struct amdtp_out_stream *s,
                                   __be32 *buffer, unsigned int frames)
{
        unsigned int i, c;

        for (i = 0; i < frames; ++i) {
                for (c = 0; c < s->pcm_channels; ++c)
                        buffer[c] = cpu_to_be32(0x40000000);
                buffer += s->data_block_quadlets;
        }
}

static void amdtp_fill_midi(struct amdtp_out_stream *s,
                            __be32 *buffer, unsigned int frames)
{
        unsigned int i;

        for (i = 0; i < frames; ++i)
                buffer[s->pcm_channels + i * s->data_block_quadlets] =
                                                cpu_to_be32(0x80000000);
}

static void queue_out_packet(struct amdtp_out_stream *s, unsigned int cycle)
{
        __be32 *buffer;
        unsigned int index, data_blocks, syt, ptr;
        struct snd_pcm_substream *pcm;
        struct fw_iso_packet packet;
        int err;

        if (s->packet_index < 0)
                return;
        index = s->packet_index;

        data_blocks = calculate_data_blocks(s);
        syt = calculate_syt(s, cycle);

        buffer = s->buffer.packets[index].buffer;
        buffer[0] = cpu_to_be32(ACCESS_ONCE(s->source_node_id_field) |
                                (s->data_block_quadlets << 16) |
                                s->data_block_counter);
        buffer[1] = cpu_to_be32(CIP_EOH | CIP_FMT_AM | AMDTP_FDF_AM824 |
                                (s->sfc << AMDTP_FDF_SFC_SHIFT) | syt);
        buffer += 2;

        pcm = ACCESS_ONCE(s->pcm);
        if (pcm)
                s->transfer_samples(s, pcm, buffer, data_blocks);
        else
                amdtp_fill_pcm_silence(s, buffer, data_blocks);
        if (s->midi_ports)
                amdtp_fill_midi(s, buffer, data_blocks);

        s->data_block_counter = (s->data_block_counter + data_blocks) & 0xff;

        packet.payload_length = 8 + data_blocks * 4 * s->data_block_quadlets;
        packet.interrupt = IS_ALIGNED(index + 1, INTERRUPT_INTERVAL);
        packet.skip = 0;
        packet.tag = TAG_CIP;
        packet.sy = 0;
        packet.header_length = 0;

        err = fw_iso_context_queue(s->context, &packet, &s->buffer.iso_buffer,
                                   s->buffer.packets[index].offset);
        if (err < 0) {
                dev_err(&s->unit->device, "queueing error: %d\n", err);
                s->packet_index = -1;
                amdtp_out_stream_pcm_abort(s);
                return;
        }

        if (++index >= QUEUE_LENGTH)
                index = 0;
        s->packet_index = index;

        if (pcm) {
                ptr = s->pcm_buffer_pointer + data_blocks;
                if (ptr >= pcm->runtime->buffer_size)
                        ptr -= pcm->runtime->buffer_size;
                ACCESS_ONCE(s->pcm_buffer_pointer) = ptr;

                s->pcm_period_pointer += data_blocks;
                if (s->pcm_period_pointer >= pcm->runtime->period_size) {
                        s->pcm_period_pointer -= pcm->runtime->period_size;
                        s->pointer_flush = false;
                        tasklet_hi_schedule(&s->period_tasklet);
                }
        }
}

static void pcm_period_tasklet(unsigned long data)
{
        struct amdtp_out_stream *s = (void *)data;
        struct snd_pcm_substream *pcm = ACCESS_ONCE(s->pcm);

        if (pcm)
                snd_pcm_period_elapsed(pcm);
}

static void out_packet_callback(struct fw_iso_context *context, u32 cycle,
                                size_t header_length, void *header, void *data)
{
        struct amdtp_out_stream *s = data;
        unsigned int i, packets = header_length / 4;

        /*
         * Compute the cycle of the last queued packet.
         * (We need only the four lowest bits for the SYT, so we can ignore
         * that bits 0-11 must wrap around at 3072.)
         */
        cycle += QUEUE_LENGTH - packets;

        for (i = 0; i < packets; ++i)
                queue_out_packet(s, ++cycle);
        fw_iso_context_queue_flush(s->context);
}

static int queue_initial_skip_packets(struct amdtp_out_stream *s)
{
        struct fw_iso_packet skip_packet = {
                .skip = 1,
        };
        unsigned int i;
        int err;

        for (i = 0; i < QUEUE_LENGTH; ++i) {
                skip_packet.interrupt = IS_ALIGNED(s->packet_index + 1,
                                                   INTERRUPT_INTERVAL);
                err = fw_iso_context_queue(s->context, &skip_packet, NULL, 0);
                if (err < 0)
                        return err;
                if (++s->packet_index >= QUEUE_LENGTH)
                        s->packet_index = 0;
        }

        return 0;
}

/**
 * amdtp_out_stream_start - start sending packets
 * @s: the AMDTP output stream to start
 * @channel: the isochronous channel on the bus
 * @speed: firewire speed code
 *
 * The stream cannot be started until it has been configured with
 * amdtp_out_stream_set_hw_params(), amdtp_out_stream_set_pcm(), and
 * amdtp_out_stream_set_midi(); and it must be started before any
 * PCM or MIDI device can be started.
 */
int amdtp_out_stream_start(struct amdtp_out_stream *s, int channel, int speed)
{
        static const struct {
                unsigned int data_block;
                unsigned int syt_offset;
        } initial_state[] = {
                [CIP_SFC_32000]  = {  4, 3072 },
                [CIP_SFC_48000]  = {  6, 1024 },
                [CIP_SFC_96000]  = { 12, 1024 },
                [CIP_SFC_192000] = { 24, 1024 },
                [CIP_SFC_44100]  = {  0,   67 },
                [CIP_SFC_88200]  = {  0,   67 },
                [CIP_SFC_176400] = {  0,   67 },
        };
        int err;

        mutex_lock(&s->mutex);

        if (WARN_ON(!IS_ERR(s->context) ||
                    (!s->pcm_channels && !s->midi_ports))) {
                err = -EBADFD;
                goto err_unlock;
        }

        s->data_block_state = initial_state[s->sfc].data_block;
        s->syt_offset_state = initial_state[s->sfc].syt_offset;
        s->last_syt_offset = TICKS_PER_CYCLE;

        err = iso_packets_buffer_init(&s->buffer, s->unit, QUEUE_LENGTH,
                                      amdtp_out_stream_get_max_payload(s),
                                      DMA_TO_DEVICE);
        if (err < 0)
                goto err_unlock;

        s->context = fw_iso_context_create(fw_parent_device(s->unit)->card,
                                           FW_ISO_CONTEXT_TRANSMIT,
                                           channel, speed, 0,
                                           out_packet_callback, s);
        if (IS_ERR(s->context)) {
                err = PTR_ERR(s->context);
                if (err == -EBUSY)
                        dev_err(&s->unit->device,
                                "no free output stream on this controller\n");
                goto err_buffer;
        }

        amdtp_out_stream_update(s);

        s->packet_index = 0;
        s->data_block_counter = 0;
        err = queue_initial_skip_packets(s);
        if (err < 0)
                goto err_context;

        err = fw_iso_context_start(s->context, -1, 0, 0);
        if (err < 0)
                goto err_context;

        mutex_unlock(&s->mutex);

        return 0;

err_context:
        fw_iso_context_destroy(s->context);
        s->context = ERR_PTR(-1);
err_buffer:
        iso_packets_buffer_destroy(&s->buffer, s->unit);
err_unlock:
        mutex_unlock(&s->mutex);

        return err;
}
EXPORT_SYMBOL(amdtp_out_stream_start);

/**
 * amdtp_out_stream_pcm_pointer - get the PCM buffer position
 * @s: the AMDTP output stream that transports the PCM data
 *
 * Returns the current buffer position, in frames.
 */
unsigned long amdtp_out_stream_pcm_pointer(struct amdtp_out_stream *s)
{
        /* this optimization is allowed to be racy */
        if (s->pointer_flush)
                fw_iso_context_flush_completions(s->context);
        else
                s->pointer_flush = true;

        return ACCESS_ONCE(s->pcm_buffer_pointer);
}
EXPORT_SYMBOL(amdtp_out_stream_pcm_pointer);

/**
 * amdtp_out_stream_update - update the stream after a bus reset
 * @s: the AMDTP output stream
 */
void amdtp_out_stream_update(struct amdtp_out_stream *s)
{
        ACCESS_ONCE(s->source_node_id_field) =
                (fw_parent_device(s->unit)->card->node_id & 0x3f) << 24;
}
EXPORT_SYMBOL(amdtp_out_stream_update);

/**
 * amdtp_out_stream_stop - stop sending packets
 * @s: the AMDTP output stream to stop
 *
 * All PCM and MIDI devices of the stream must be stopped before the stream
 * itself can be stopped.
 */
void amdtp_out_stream_stop(struct amdtp_out_stream *s)
{
        mutex_lock(&s->mutex);

        if (IS_ERR(s->context)) {
                mutex_unlock(&s->mutex);
                return;
        }

        tasklet_kill(&s->period_tasklet);
        fw_iso_context_stop(s->context);
        fw_iso_context_destroy(s->context);
        s->context = ERR_PTR(-1);
        iso_packets_buffer_destroy(&s->buffer, s->unit);

        mutex_unlock(&s->mutex);
}
EXPORT_SYMBOL(amdtp_out_stream_stop);

/**
 * amdtp_out_stream_pcm_abort - abort the running PCM device
 * @s: the AMDTP stream about to be stopped
 *
 * If the isochronous stream needs to be stopped asynchronously, call this
 * function first to stop the PCM device.
 */
void amdtp_out_stream_pcm_abort(struct amdtp_out_stream *s)
{
        struct snd_pcm_substream *pcm;

        pcm = ACCESS_ONCE(s->pcm);
        if (pcm) {
                snd_pcm_stream_lock_irq(pcm);
                if (snd_pcm_running(pcm))
                        snd_pcm_stop(pcm, SNDRV_PCM_STATE_XRUN);
                snd_pcm_stream_unlock_irq(pcm);
        }
}
EXPORT_SYMBOL(amdtp_out_stream_pcm_abort);