// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * sh_dac_audio.c - SuperH DAC audio driver for ALSA
 *
 * Copyright (c) 2009 by Rafael Ignacio Zurita <rizurita@yahoo.com>
 *
 * Based on sh_dac_audio.c (Copyright (C) 2004, 2005 by Andriy Skulysh)
 */

#include <linux/hrtimer.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <sound/core.h>
#include <sound/initval.h>
#include <sound/pcm.h>
#include <sound/sh_dac_audio.h>
#include <asm/clock.h>
#include <asm/hd64461.h>
#include <mach/hp6xx.h>
#include <cpu/dac.h>

MODULE_AUTHOR("Rafael Ignacio Zurita <rizurita@yahoo.com>");
MODULE_DESCRIPTION("SuperH DAC audio driver");
MODULE_LICENSE("GPL");

/* Module Parameters */
static int index = SNDRV_DEFAULT_IDX1;
static char *id = SNDRV_DEFAULT_STR1;
module_param(index, int, 0444);
MODULE_PARM_DESC(index, "Index value for SuperH DAC audio.");
module_param(id, charp, 0444);
MODULE_PARM_DESC(id, "ID string for SuperH DAC audio.");

/* main struct */
struct snd_sh_dac {
        struct snd_card *card;
        struct snd_pcm_substream *substream;
        struct hrtimer hrtimer;
        ktime_t wakeups_per_second;

        int rate;
        int empty;
        char *data_buffer, *buffer_begin, *buffer_end;
        int processed; /* bytes proccesed, to compare with period_size */
        int buffer_size;
        struct dac_audio_pdata *pdata;
};


static void dac_audio_start_timer(struct snd_sh_dac *chip)
{
        hrtimer_start(&chip->hrtimer, chip->wakeups_per_second,
                      HRTIMER_MODE_REL);
}

static void dac_audio_stop_timer(struct snd_sh_dac *chip)
{
        hrtimer_cancel(&chip->hrtimer);
}

static void dac_audio_reset(struct snd_sh_dac *chip)
{
        dac_audio_stop_timer(chip);
        chip->buffer_begin = chip->buffer_end = chip->data_buffer;
        chip->processed = 0;
        chip->empty = 1;
}

static void dac_audio_set_rate(struct snd_sh_dac *chip)
{
        chip->wakeups_per_second = 1000000000 / chip->rate;
}


/* PCM INTERFACE */

static const struct snd_pcm_hardware snd_sh_dac_pcm_hw = {
        .info                   = (SNDRV_PCM_INFO_MMAP |
                                        SNDRV_PCM_INFO_MMAP_VALID |
                                        SNDRV_PCM_INFO_INTERLEAVED |
                                        SNDRV_PCM_INFO_HALF_DUPLEX),
        .formats                = SNDRV_PCM_FMTBIT_U8,
        .rates                  = SNDRV_PCM_RATE_8000,
        .rate_min               = 8000,
        .rate_max               = 8000,
        .channels_min           = 1,
        .channels_max           = 1,
        .buffer_bytes_max       = (48*1024),
        .period_bytes_min       = 1,
        .period_bytes_max       = (48*1024),
        .periods_min            = 1,
        .periods_max            = 1024,
};

static int snd_sh_dac_pcm_open(struct snd_pcm_substream *substream)
{
        struct snd_sh_dac *chip = snd_pcm_substream_chip(substream);
        struct snd_pcm_runtime *runtime = substream->runtime;

        runtime->hw = snd_sh_dac_pcm_hw;

        chip->substream = substream;
        chip->buffer_begin = chip->buffer_end = chip->data_buffer;
        chip->processed = 0;
        chip->empty = 1;

        chip->pdata->start(chip->pdata);

        return 0;
}

static int snd_sh_dac_pcm_close(struct snd_pcm_substream *substream)
{
        struct snd_sh_dac *chip = snd_pcm_substream_chip(substream);

        chip->substream = NULL;

        dac_audio_stop_timer(chip);
        chip->pdata->stop(chip->pdata);

        return 0;
}

static int snd_sh_dac_pcm_prepare(struct snd_pcm_substream *substream)
{
        struct snd_sh_dac *chip = snd_pcm_substream_chip(substream);
        struct snd_pcm_runtime *runtime = chip->substream->runtime;

        chip->buffer_size = runtime->buffer_size;
        memset(chip->data_buffer, 0, chip->pdata->buffer_size);

        return 0;
}

static int snd_sh_dac_pcm_trigger(struct snd_pcm_substream *substream, int cmd)
{
        struct snd_sh_dac *chip = snd_pcm_substream_chip(substream);

        switch (cmd) {
        case SNDRV_PCM_TRIGGER_START:
                dac_audio_start_timer(chip);
                break;
        case SNDRV_PCM_TRIGGER_STOP:
                chip->buffer_begin = chip->buffer_end = chip->data_buffer;
                chip->processed = 0;
                chip->empty = 1;
                dac_audio_stop_timer(chip);
                break;
        default:
                 return -EINVAL;
        }

        return 0;
}

static int snd_sh_dac_pcm_copy(struct snd_pcm_substream *substream,
                               int channel, unsigned long pos,
                               struct iov_iter *src, unsigned long count)
{
        /* channel is not used (interleaved data) */
        struct snd_sh_dac *chip = snd_pcm_substream_chip(substream);

        if (copy_from_iter(chip->data_buffer + pos, count, src) != count)
                return -EFAULT;
        chip->buffer_end = chip->data_buffer + pos + count;

        if (chip->empty) {
                chip->empty = 0;
                dac_audio_start_timer(chip);
        }

        return 0;
}

static int snd_sh_dac_pcm_silence(struct snd_pcm_substream *substream,
                                  int channel, unsigned long pos,
                                  unsigned long count)
{
        /* channel is not used (interleaved data) */
        struct snd_sh_dac *chip = snd_pcm_substream_chip(substream);

        memset(chip->data_buffer + pos, 0, count);
        chip->buffer_end = chip->data_buffer + pos + count;

        if (chip->empty) {
                chip->empty = 0;
                dac_audio_start_timer(chip);
        }

        return 0;
}

static
snd_pcm_uframes_t snd_sh_dac_pcm_pointer(struct snd_pcm_substream *substream)
{
        struct snd_sh_dac *chip = snd_pcm_substream_chip(substream);
        int pointer = chip->buffer_begin - chip->data_buffer;

        return pointer;
}

/* pcm ops */
static const struct snd_pcm_ops snd_sh_dac_pcm_ops = {
        .open           = snd_sh_dac_pcm_open,
        .close          = snd_sh_dac_pcm_close,
        .prepare        = snd_sh_dac_pcm_prepare,
        .trigger        = snd_sh_dac_pcm_trigger,
        .pointer        = snd_sh_dac_pcm_pointer,
        .copy           = snd_sh_dac_pcm_copy,
        .fill_silence   = snd_sh_dac_pcm_silence,
};

static int snd_sh_dac_pcm(struct snd_sh_dac *chip, int device)
{
        int err;
        struct snd_pcm *pcm;

        /* device should be always 0 for us */
        err = snd_pcm_new(chip->card, "SH_DAC PCM", device, 1, 0, &pcm);
        if (err < 0)
                return err;

        pcm->private_data = chip;
        strscpy(pcm->name, "SH_DAC PCM");
        snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_PLAYBACK, &snd_sh_dac_pcm_ops);

        /* buffer size=48K */
        snd_pcm_set_managed_buffer_all(pcm, SNDRV_DMA_TYPE_CONTINUOUS,
                                       NULL, 48 * 1024, 48 * 1024);

        return 0;
}
/* END OF PCM INTERFACE */


/* driver .remove  --  destructor */
static void snd_sh_dac_remove(struct platform_device *devptr)
{
        snd_card_free(platform_get_drvdata(devptr));
}

/* free -- it has been defined by create */
static int snd_sh_dac_free(struct snd_sh_dac *chip)
{
        /* release the data */
        kfree(chip->data_buffer);
        kfree(chip);

        return 0;
}

static int snd_sh_dac_dev_free(struct snd_device *device)
{
        struct snd_sh_dac *chip = device->device_data;

        return snd_sh_dac_free(chip);
}

static enum hrtimer_restart sh_dac_audio_timer(struct hrtimer *handle)
{
        struct snd_sh_dac *chip = container_of(handle, struct snd_sh_dac,
                                               hrtimer);
        struct snd_pcm_runtime *runtime = chip->substream->runtime;
        ssize_t b_ps = frames_to_bytes(runtime, runtime->period_size);

        if (!chip->empty) {
                sh_dac_output(*chip->buffer_begin, chip->pdata->channel);
                chip->buffer_begin++;

                chip->processed++;
                if (chip->processed >= b_ps) {
                        chip->processed -= b_ps;
                        snd_pcm_period_elapsed(chip->substream);
                }

                if (chip->buffer_begin == (chip->data_buffer +
                                           chip->buffer_size - 1))
                        chip->buffer_begin = chip->data_buffer;

                if (chip->buffer_begin == chip->buffer_end)
                        chip->empty = 1;

        }

        if (!chip->empty)
                hrtimer_start(&chip->hrtimer, chip->wakeups_per_second,
                              HRTIMER_MODE_REL);

        return HRTIMER_NORESTART;
}

/* create  --  chip-specific constructor for the cards components */
static int snd_sh_dac_create(struct snd_card *card,
                             struct platform_device *devptr,
                             struct snd_sh_dac **rchip)
{
        struct snd_sh_dac *chip;
        int err;

        static const struct snd_device_ops ops = {
                   .dev_free = snd_sh_dac_dev_free,
        };

        *rchip = NULL;

        chip = kzalloc_obj(*chip);
        if (chip == NULL)
                return -ENOMEM;

        chip->card = card;

        hrtimer_setup(&chip->hrtimer, sh_dac_audio_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);

        dac_audio_reset(chip);
        chip->rate = 8000;
        dac_audio_set_rate(chip);

        chip->pdata = devptr->dev.platform_data;

        chip->data_buffer = kmalloc(chip->pdata->buffer_size, GFP_KERNEL);
        if (chip->data_buffer == NULL) {
                kfree(chip);
                return -ENOMEM;
        }

        err = snd_device_new(card, SNDRV_DEV_LOWLEVEL, chip, &ops);
        if (err < 0) {
                snd_sh_dac_free(chip);
                return err;
        }

        *rchip = chip;

        return 0;
}

/* driver .probe  --  constructor */
static int snd_sh_dac_probe(struct platform_device *devptr)
{
        struct snd_sh_dac *chip;
        struct snd_card *card;
        int err;

        err = snd_card_new(&devptr->dev, index, id, THIS_MODULE, 0, &card);
        if (err < 0) {
                dev_err(&devptr->dev, "cannot allocate the card\n");
                return err;
        }

        err = snd_sh_dac_create(card, devptr, &chip);
        if (err < 0)
                goto probe_error;

        err = snd_sh_dac_pcm(chip, 0);
        if (err < 0)
                goto probe_error;

        strscpy(card->driver, "snd_sh_dac");
        strscpy(card->shortname, "SuperH DAC audio driver");
        dev_info(&devptr->dev, "%s %s\n", card->longname, card->shortname);

        err = snd_card_register(card);
        if (err < 0)
                goto probe_error;

        dev_info(&devptr->dev, "ALSA driver for SuperH DAC audio\n");

        platform_set_drvdata(devptr, card);
        return 0;

probe_error:
        snd_card_free(card);
        return err;
}

/*
 * "driver" definition
 */
static struct platform_driver sh_dac_driver = {
        .probe  = snd_sh_dac_probe,
        .remove = snd_sh_dac_remove,
        .driver = {
                .name = "dac_audio",
        },
};

module_platform_driver(sh_dac_driver);