/*
 * sound.c - Audio Application Interface Module for Mostcore
 *
 * Copyright (C) 2015 Microchip Technology Germany II GmbH & Co. KG
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * This file is licensed under GPLv2.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/printk.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <sound/core.h>
#include <sound/pcm.h>
#include <sound/pcm_params.h>
#include <linux/sched.h>
#include <linux/kthread.h>
#include <mostcore.h>

#define DRIVER_NAME "sound"

static struct list_head dev_list;
static struct most_aim audio_aim;

/**
 * struct channel - private structure to keep channel specific data
 * @substream: stores the substream structure
 * @iface: interface for which the channel belongs to
 * @cfg: channel configuration
 * @card: registered sound card
 * @list: list for private use
 * @id: channel index
 * @period_pos: current period position (ring buffer)
 * @buffer_pos: current buffer position (ring buffer)
 * @is_stream_running: identifies whether a stream is running or not
 * @opened: set when the stream is opened
 * @playback_task: playback thread
 * @playback_waitq: waitq used by playback thread
 */
struct channel {
        struct snd_pcm_substream *substream;
        struct snd_pcm_hardware pcm_hardware;
        struct most_interface *iface;
        struct most_channel_config *cfg;
        struct snd_card *card;
        struct list_head list;
        int id;
        unsigned int period_pos;
        unsigned int buffer_pos;
        bool is_stream_running;

        struct task_struct *playback_task;
        wait_queue_head_t playback_waitq;

        void (*copy_fn)(void *alsa, void *most, unsigned int bytes);
};

#define MOST_PCM_INFO (SNDRV_PCM_INFO_MMAP | \
                       SNDRV_PCM_INFO_MMAP_VALID | \
                       SNDRV_PCM_INFO_BATCH | \
                       SNDRV_PCM_INFO_INTERLEAVED | \
                       SNDRV_PCM_INFO_BLOCK_TRANSFER)

#define swap16(val) ( \
        (((u16)(val) << 8) & (u16)0xFF00) | \
        (((u16)(val) >> 8) & (u16)0x00FF))

#define swap32(val) ( \
        (((u32)(val) << 24) & (u32)0xFF000000) | \
        (((u32)(val) <<  8) & (u32)0x00FF0000) | \
        (((u32)(val) >>  8) & (u32)0x0000FF00) | \
        (((u32)(val) >> 24) & (u32)0x000000FF))

static void swap_copy16(u16 *dest, const u16 *source, unsigned int bytes)
{
        unsigned int i = 0;

        while (i < (bytes / 2)) {
                dest[i] = swap16(source[i]);
                i++;
        }
}

static void swap_copy24(u8 *dest, const u8 *source, unsigned int bytes)
{
        unsigned int i = 0;

        while (i < bytes - 2) {
                dest[i] = source[i + 2];
                dest[i + 1] = source[i + 1];
                dest[i + 2] = source[i];
                i += 3;
        }
}

static void swap_copy32(u32 *dest, const u32 *source, unsigned int bytes)
{
        unsigned int i = 0;

        while (i < bytes / 4) {
                dest[i] = swap32(source[i]);
                i++;
        }
}

static void alsa_to_most_memcpy(void *alsa, void *most, unsigned int bytes)
{
        memcpy(most, alsa, bytes);
}

static void alsa_to_most_copy16(void *alsa, void *most, unsigned int bytes)
{
        swap_copy16(most, alsa, bytes);
}

static void alsa_to_most_copy24(void *alsa, void *most, unsigned int bytes)
{
        swap_copy24(most, alsa, bytes);
}

static void alsa_to_most_copy32(void *alsa, void *most, unsigned int bytes)
{
        swap_copy32(most, alsa, bytes);
}

static void most_to_alsa_memcpy(void *alsa, void *most, unsigned int bytes)
{
        memcpy(alsa, most, bytes);
}

static void most_to_alsa_copy16(void *alsa, void *most, unsigned int bytes)
{
        swap_copy16(alsa, most, bytes);
}

static void most_to_alsa_copy24(void *alsa, void *most, unsigned int bytes)
{
        swap_copy24(alsa, most, bytes);
}

static void most_to_alsa_copy32(void *alsa, void *most, unsigned int bytes)
{
        swap_copy32(alsa, most, bytes);
}

/**
 * get_channel - get pointer to channel
 * @iface: interface structure
 * @channel_id: channel ID
 *
 * This traverses the channel list and returns the channel matching the
 * ID and interface.
 *
 * Returns pointer to channel on success or NULL otherwise.
 */
static struct channel *get_channel(struct most_interface *iface,
                                   int channel_id)
{
        struct channel *channel, *tmp;

        list_for_each_entry_safe(channel, tmp, &dev_list, list) {
                if ((channel->iface == iface) && (channel->id == channel_id))
                        return channel;
        }

        return NULL;
}

/**
 * copy_data - implements data copying function
 * @channel: channel
 * @mbo: MBO from core
 *
 * Copy data from/to ring buffer to/from MBO and update the buffer position
 */
static bool copy_data(struct channel *channel, struct mbo *mbo)
{
        struct snd_pcm_runtime *const runtime = channel->substream->runtime;
        unsigned int const frame_bytes = channel->cfg->subbuffer_size;
        unsigned int const buffer_size = runtime->buffer_size;
        unsigned int frames;
        unsigned int fr0;

        if (channel->cfg->direction & MOST_CH_RX)
                frames = mbo->processed_length / frame_bytes;
        else
                frames = mbo->buffer_length / frame_bytes;
        fr0 = min(buffer_size - channel->buffer_pos, frames);

        channel->copy_fn(runtime->dma_area + channel->buffer_pos * frame_bytes,
                         mbo->virt_address,
                         fr0 * frame_bytes);

        if (frames > fr0) {
                /* wrap around at end of ring buffer */
                channel->copy_fn(runtime->dma_area,
                                 mbo->virt_address + fr0 * frame_bytes,
                                 (frames - fr0) * frame_bytes);
        }

        channel->buffer_pos += frames;
        if (channel->buffer_pos >= buffer_size)
                channel->buffer_pos -= buffer_size;
        channel->period_pos += frames;
        if (channel->period_pos >= runtime->period_size) {
                channel->period_pos -= runtime->period_size;
                return true;
        }

        return false;
}

/**
 * playback_thread - function implements the playback thread
 * @data: private data
 *
 * Thread which does the playback functionality in a loop. It waits for a free
 * MBO from mostcore for a particular channel and copy the data from ring buffer
 * to MBO. Submit the MBO back to mostcore, after copying the data.
 *
 * Returns 0 on success or error code otherwise.
 */
static int playback_thread(void *data)
{
        struct channel *const channel = data;

        while (!kthread_should_stop()) {
                struct mbo *mbo = NULL;
                bool period_elapsed = false;

                wait_event_interruptible(
                        channel->playback_waitq,
                        kthread_should_stop() ||
                        (channel->is_stream_running &&
                         (mbo = most_get_mbo(channel->iface, channel->id,
                                             &audio_aim))));
                if (!mbo)
                        continue;

                if (channel->is_stream_running)
                        period_elapsed = copy_data(channel, mbo);
                else
                        memset(mbo->virt_address, 0, mbo->buffer_length);

                most_submit_mbo(mbo);
                if (period_elapsed)
                        snd_pcm_period_elapsed(channel->substream);
        }

        return 0;
}

/**
 * pcm_open - implements open callback function for PCM middle layer
 * @substream: pointer to ALSA PCM substream
 *
 * This is called when a PCM substream is opened. At least, the function should
 * initialize the runtime->hw record.
 *
 * Returns 0 on success or error code otherwise.
 */
static int pcm_open(struct snd_pcm_substream *substream)
{
        struct channel *channel = substream->private_data;
        struct snd_pcm_runtime *runtime = substream->runtime;
        struct most_channel_config *cfg = channel->cfg;

        channel->substream = substream;

        if (cfg->direction == MOST_CH_TX) {
                channel->playback_task = kthread_run(playback_thread, channel,
                                                     "most_audio_playback");
                if (IS_ERR(channel->playback_task)) {
                        pr_err("Couldn't start thread\n");
                        return PTR_ERR(channel->playback_task);
                }
        }

        if (most_start_channel(channel->iface, channel->id, &audio_aim)) {
                pr_err("most_start_channel() failed!\n");
                if (cfg->direction == MOST_CH_TX)
                        kthread_stop(channel->playback_task);
                return -EBUSY;
        }

        runtime->hw = channel->pcm_hardware;
        return 0;
}

/**
 * pcm_close - implements close callback function for PCM middle layer
 * @substream: sub-stream pointer
 *
 * Obviously, this is called when a PCM substream is closed. Any private
 * instance for a PCM substream allocated in the open callback will be
 * released here.
 *
 * Returns 0 on success or error code otherwise.
 */
static int pcm_close(struct snd_pcm_substream *substream)
{
        struct channel *channel = substream->private_data;

        if (channel->cfg->direction == MOST_CH_TX)
                kthread_stop(channel->playback_task);
        most_stop_channel(channel->iface, channel->id, &audio_aim);

        return 0;
}

/**
 * pcm_hw_params - implements hw_params callback function for PCM middle layer
 * @substream: sub-stream pointer
 * @hw_params: contains the hardware parameters set by the application
 *
 * This is called when the hardware parameters is set by the application, that
 * is, once when the buffer size, the period size, the format, etc. are defined
 * for the PCM substream. Many hardware setups should be done is this callback,
 * including the allocation of buffers.
 *
 * Returns 0 on success or error code otherwise.
 */
static int pcm_hw_params(struct snd_pcm_substream *substream,
                         struct snd_pcm_hw_params *hw_params)
{
        struct channel *channel = substream->private_data;

        if ((params_channels(hw_params) > channel->pcm_hardware.channels_max) ||
            (params_channels(hw_params) < channel->pcm_hardware.channels_min)) {
                pr_err("Requested number of channels not supported.\n");
                return -EINVAL;
        }
        return snd_pcm_lib_alloc_vmalloc_buffer(substream,
                                                params_buffer_bytes(hw_params));
}

/**
 * pcm_hw_free - implements hw_free callback function for PCM middle layer
 * @substream: substream pointer
 *
 * This is called to release the resources allocated via hw_params.
 * This function will be always called before the close callback is called.
 *
 * Returns 0 on success or error code otherwise.
 */
static int pcm_hw_free(struct snd_pcm_substream *substream)
{
        return snd_pcm_lib_free_vmalloc_buffer(substream);
}

/**
 * pcm_prepare - implements prepare callback function for PCM middle layer
 * @substream: substream pointer
 *
 * This callback is called when the PCM is "prepared". Format rate, sample rate,
 * etc., can be set here. This callback can be called many times at each setup.
 *
 * Returns 0 on success or error code otherwise.
 */
static int pcm_prepare(struct snd_pcm_substream *substream)
{
        struct channel *channel = substream->private_data;
        struct snd_pcm_runtime *runtime = substream->runtime;
        struct most_channel_config *cfg = channel->cfg;
        int width = snd_pcm_format_physical_width(runtime->format);

        channel->copy_fn = NULL;

        if (cfg->direction == MOST_CH_TX) {
                if (snd_pcm_format_big_endian(runtime->format) || width == 8)
                        channel->copy_fn = alsa_to_most_memcpy;
                else if (width == 16)
                        channel->copy_fn = alsa_to_most_copy16;
                else if (width == 24)
                        channel->copy_fn = alsa_to_most_copy24;
                else if (width == 32)
                        channel->copy_fn = alsa_to_most_copy32;
        } else {
                if (snd_pcm_format_big_endian(runtime->format) || width == 8)
                        channel->copy_fn = most_to_alsa_memcpy;
                else if (width == 16)
                        channel->copy_fn = most_to_alsa_copy16;
                else if (width == 24)
                        channel->copy_fn = most_to_alsa_copy24;
                else if (width == 32)
                        channel->copy_fn = most_to_alsa_copy32;
        }

        if (!channel->copy_fn) {
                pr_err("unsupported format\n");
                return -EINVAL;
        }

        channel->period_pos = 0;
        channel->buffer_pos = 0;

        return 0;
}

/**
 * pcm_trigger - implements trigger callback function for PCM middle layer
 * @substream: substream pointer
 * @cmd: action to perform
 *
 * This is called when the PCM is started, stopped or paused. The action will be
 * specified in the second argument, SNDRV_PCM_TRIGGER_XXX
 *
 * Returns 0 on success or error code otherwise.
 */
static int pcm_trigger(struct snd_pcm_substream *substream, int cmd)
{
        struct channel *channel = substream->private_data;

        switch (cmd) {
        case SNDRV_PCM_TRIGGER_START:
                channel->is_stream_running = true;
                wake_up_interruptible(&channel->playback_waitq);
                return 0;

        case SNDRV_PCM_TRIGGER_STOP:
                channel->is_stream_running = false;
                return 0;

        default:
                pr_info("%s(), invalid\n", __func__);
                return -EINVAL;
        }
        return 0;
}

/**
 * pcm_pointer - implements pointer callback function for PCM middle layer
 * @substream: substream pointer
 *
 * This callback is called when the PCM middle layer inquires the current
 * hardware position on the buffer. The position must be returned in frames,
 * ranging from 0 to buffer_size-1.
 */
static snd_pcm_uframes_t pcm_pointer(struct snd_pcm_substream *substream)
{
        struct channel *channel = substream->private_data;

        return channel->buffer_pos;
}

/**
 * Initialization of struct snd_pcm_ops
 */
static const struct snd_pcm_ops pcm_ops = {
        .open       = pcm_open,
        .close      = pcm_close,
        .ioctl      = snd_pcm_lib_ioctl,
        .hw_params  = pcm_hw_params,
        .hw_free    = pcm_hw_free,
        .prepare    = pcm_prepare,
        .trigger    = pcm_trigger,
        .pointer    = pcm_pointer,
        .page       = snd_pcm_lib_get_vmalloc_page,
        .mmap       = snd_pcm_lib_mmap_vmalloc,
};

static int split_arg_list(char *buf, char **card_name, char **pcm_format)
{
        *card_name = strsep(&buf, ".");
        if (!*card_name)
                return -EIO;
        *pcm_format = strsep(&buf, ".\n");
        if (!*pcm_format)
                return -EIO;
        return 0;
}

static int audio_set_hw_params(struct snd_pcm_hardware *pcm_hw,
                               char *pcm_format,
                               struct most_channel_config *cfg)
{
        pcm_hw->info = MOST_PCM_INFO;
        pcm_hw->rates = SNDRV_PCM_RATE_48000;
        pcm_hw->rate_min = 48000;
        pcm_hw->rate_max = 48000;
        pcm_hw->buffer_bytes_max = cfg->num_buffers * cfg->buffer_size;
        pcm_hw->period_bytes_min = cfg->buffer_size;
        pcm_hw->period_bytes_max = cfg->buffer_size;
        pcm_hw->periods_min = 1;
        pcm_hw->periods_max = cfg->num_buffers;

        if (!strcmp(pcm_format, "1x8")) {
                if (cfg->subbuffer_size != 1)
                        goto error;
                pr_info("PCM format is 8-bit mono\n");
                pcm_hw->channels_min = 1;
                pcm_hw->channels_max = 1;
                pcm_hw->formats = SNDRV_PCM_FMTBIT_S8;
        } else if (!strcmp(pcm_format, "2x16")) {
                if (cfg->subbuffer_size != 4)
                        goto error;
                pr_info("PCM format is 16-bit stereo\n");
                pcm_hw->channels_min = 2;
                pcm_hw->channels_max = 2;
                pcm_hw->formats = SNDRV_PCM_FMTBIT_S16_LE |
                                  SNDRV_PCM_FMTBIT_S16_BE;
        } else if (!strcmp(pcm_format, "2x24")) {
                if (cfg->subbuffer_size != 6)
                        goto error;
                pr_info("PCM format is 24-bit stereo\n");
                pcm_hw->channels_min = 2;
                pcm_hw->channels_max = 2;
                pcm_hw->formats = SNDRV_PCM_FMTBIT_S24_3LE |
                                  SNDRV_PCM_FMTBIT_S24_3BE;
        } else if (!strcmp(pcm_format, "2x32")) {
                if (cfg->subbuffer_size != 8)
                        goto error;
                pr_info("PCM format is 32-bit stereo\n");
                pcm_hw->channels_min = 2;
                pcm_hw->channels_max = 2;
                pcm_hw->formats = SNDRV_PCM_FMTBIT_S32_LE |
                                  SNDRV_PCM_FMTBIT_S32_BE;
        } else if (!strcmp(pcm_format, "6x16")) {
                if (cfg->subbuffer_size != 12)
                        goto error;
                pr_info("PCM format is 16-bit 5.1 multi channel\n");
                pcm_hw->channels_min = 6;
                pcm_hw->channels_max = 6;
                pcm_hw->formats = SNDRV_PCM_FMTBIT_S16_LE |
                                  SNDRV_PCM_FMTBIT_S16_BE;
        } else {
                pr_err("PCM format %s not supported\n", pcm_format);
                return -EIO;
        }
        return 0;
error:
        pr_err("Audio resolution doesn't fit subbuffer size\n");
        return -EINVAL;
}

/**
 * audio_probe_channel - probe function of the driver module
 * @iface: pointer to interface instance
 * @channel_id: channel index/ID
 * @cfg: pointer to actual channel configuration
 * @parent: pointer to kobject (needed for sysfs hook-up)
 * @arg_list: string that provides the name of the device to be created in /dev
 *            plus the desired audio resolution
 *
 * Creates sound card, pcm device, sets pcm ops and registers sound card.
 *
 * Returns 0 on success or error code otherwise.
 */
static int audio_probe_channel(struct most_interface *iface, int channel_id,
                               struct most_channel_config *cfg,
                               struct kobject *parent, char *arg_list)
{
        struct channel *channel;
        struct snd_card *card;
        struct snd_pcm *pcm;
        int playback_count = 0;
        int capture_count = 0;
        int ret;
        int direction;
        char *card_name;
        char *pcm_format;

        if (!iface)
                return -EINVAL;

        if (cfg->data_type != MOST_CH_SYNC) {
                pr_err("Incompatible channel type\n");
                return -EINVAL;
        }

        if (get_channel(iface, channel_id)) {
                pr_err("channel (%s:%d) is already linked\n",
                       iface->description, channel_id);
                return -EINVAL;
        }

        if (cfg->direction == MOST_CH_TX) {
                playback_count = 1;
                direction = SNDRV_PCM_STREAM_PLAYBACK;
        } else {
                capture_count = 1;
                direction = SNDRV_PCM_STREAM_CAPTURE;
        }

        ret = split_arg_list(arg_list, &card_name, &pcm_format);
        if (ret < 0) {
                pr_info("PCM format missing\n");
                return ret;
        }

        ret = snd_card_new(NULL, -1, card_name, THIS_MODULE,
                           sizeof(*channel), &card);
        if (ret < 0)
                return ret;

        channel = card->private_data;
        channel->card = card;
        channel->cfg = cfg;
        channel->iface = iface;
        channel->id = channel_id;
        init_waitqueue_head(&channel->playback_waitq);

        ret = audio_set_hw_params(&channel->pcm_hardware, pcm_format, cfg);
        if (ret)
                goto err_free_card;

        snprintf(card->driver, sizeof(card->driver), "%s", DRIVER_NAME);
        snprintf(card->shortname, sizeof(card->shortname), "Microchip MOST:%d",
                 card->number);
        snprintf(card->longname, sizeof(card->longname), "%s at %s, ch %d",
                 card->shortname, iface->description, channel_id);

        ret = snd_pcm_new(card, card_name, 0, playback_count,
                          capture_count, &pcm);
        if (ret < 0)
                goto err_free_card;

        pcm->private_data = channel;

        snd_pcm_set_ops(pcm, direction, &pcm_ops);

        ret = snd_card_register(card);
        if (ret < 0)
                goto err_free_card;

        list_add_tail(&channel->list, &dev_list);

        return 0;

err_free_card:
        snd_card_free(card);
        return ret;
}

/**
 * audio_disconnect_channel - function to disconnect a channel
 * @iface: pointer to interface instance
 * @channel_id: channel index
 *
 * This frees allocated memory and removes the sound card from ALSA
 *
 * Returns 0 on success or error code otherwise.
 */
static int audio_disconnect_channel(struct most_interface *iface,
                                    int channel_id)
{
        struct channel *channel;

        channel = get_channel(iface, channel_id);
        if (!channel) {
                pr_err("sound_disconnect_channel(), invalid channel %d\n",
                       channel_id);
                return -EINVAL;
        }

        list_del(&channel->list);
        snd_card_free(channel->card);

        return 0;
}

/**
 * audio_rx_completion - completion handler for rx channels
 * @mbo: pointer to buffer object that has completed
 *
 * This searches for the channel this MBO belongs to and copy the data from MBO
 * to ring buffer
 *
 * Returns 0 on success or error code otherwise.
 */
static int audio_rx_completion(struct mbo *mbo)
{
        struct channel *channel = get_channel(mbo->ifp, mbo->hdm_channel_id);
        bool period_elapsed = false;

        if (!channel) {
                pr_err("sound_rx_completion(), invalid channel %d\n",
                       mbo->hdm_channel_id);
                return -EINVAL;
        }

        if (channel->is_stream_running)
                period_elapsed = copy_data(channel, mbo);

        most_put_mbo(mbo);

        if (period_elapsed)
                snd_pcm_period_elapsed(channel->substream);

        return 0;
}

/**
 * audio_tx_completion - completion handler for tx channels
 * @iface: pointer to interface instance
 * @channel_id: channel index/ID
 *
 * This searches the channel that belongs to this combination of interface
 * pointer and channel ID and wakes a process sitting in the wait queue of
 * this channel.
 *
 * Returns 0 on success or error code otherwise.
 */
static int audio_tx_completion(struct most_interface *iface, int channel_id)
{
        struct channel *channel = get_channel(iface, channel_id);

        if (!channel) {
                pr_err("sound_tx_completion(), invalid channel %d\n",
                       channel_id);
                return -EINVAL;
        }

        wake_up_interruptible(&channel->playback_waitq);

        return 0;
}

/**
 * Initialization of the struct most_aim
 */
static struct most_aim audio_aim = {
        .name = DRIVER_NAME,
        .probe_channel = audio_probe_channel,
        .disconnect_channel = audio_disconnect_channel,
        .rx_completion = audio_rx_completion,
        .tx_completion = audio_tx_completion,
};

static int __init audio_init(void)
{
        pr_info("init()\n");

        INIT_LIST_HEAD(&dev_list);

        return most_register_aim(&audio_aim);
}

static void __exit audio_exit(void)
{
        struct channel *channel, *tmp;

        pr_info("exit()\n");

        list_for_each_entry_safe(channel, tmp, &dev_list, list) {
                list_del(&channel->list);
                snd_card_free(channel->card);
        }

        most_deregister_aim(&audio_aim);
}

module_init(audio_init);
module_exit(audio_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Christian Gromm <christian.gromm@microchip.com>");
MODULE_DESCRIPTION("Audio Application Interface Module for MostCore");