/*
 * Xtfpga I2S controller driver
 *
 * Copyright (c) 2014 Cadence Design Systems Inc.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/clk.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/pm_runtime.h>
#include <sound/pcm_params.h>
#include <sound/soc.h>

#define DRV_NAME        "xtfpga-i2s"

#define XTFPGA_I2S_VERSION      0x00
#define XTFPGA_I2S_CONFIG       0x04
#define XTFPGA_I2S_INT_MASK     0x08
#define XTFPGA_I2S_INT_STATUS   0x0c
#define XTFPGA_I2S_CHAN0_DATA   0x10
#define XTFPGA_I2S_CHAN1_DATA   0x14
#define XTFPGA_I2S_CHAN2_DATA   0x18
#define XTFPGA_I2S_CHAN3_DATA   0x1c

#define XTFPGA_I2S_CONFIG_TX_ENABLE     0x1
#define XTFPGA_I2S_CONFIG_INT_ENABLE    0x2
#define XTFPGA_I2S_CONFIG_LEFT          0x4
#define XTFPGA_I2S_CONFIG_RATIO_BASE    8
#define XTFPGA_I2S_CONFIG_RATIO_MASK    0x0000ff00
#define XTFPGA_I2S_CONFIG_RES_BASE      16
#define XTFPGA_I2S_CONFIG_RES_MASK      0x003f0000
#define XTFPGA_I2S_CONFIG_LEVEL_BASE    24
#define XTFPGA_I2S_CONFIG_LEVEL_MASK    0x0f000000
#define XTFPGA_I2S_CONFIG_CHANNEL_BASE  28

#define XTFPGA_I2S_INT_UNDERRUN         0x1
#define XTFPGA_I2S_INT_LEVEL            0x2
#define XTFPGA_I2S_INT_VALID            0x3

#define XTFPGA_I2S_FIFO_SIZE            8192

/*
 * I2S controller operation:
 *
 * Enabling TX: output 1 period of zeros (starting with left channel)
 * and then queued data.
 *
 * Level status and interrupt: whenever FIFO level is below FIFO trigger,
 * level status is 1 and an IRQ is asserted (if enabled).
 *
 * Underrun status and interrupt: whenever FIFO is empty, underrun status
 * is 1 and an IRQ is asserted (if enabled).
 */
struct xtfpga_i2s {
        struct device *dev;
        struct clk *clk;
        struct regmap *regmap;
        void __iomem *regs;

        /* current playback substream. NULL if not playing.
         *
         * Access to that field is synchronized between the interrupt handler
         * and userspace through RCU.
         *
         * Interrupt handler (threaded part) does PIO on substream data in RCU
         * read-side critical section. Trigger callback sets and clears the
         * pointer when the playback is started and stopped with
         * rcu_assign_pointer. When userspace is about to free the playback
         * stream in the pcm_close callback it synchronizes with the interrupt
         * handler by means of synchronize_rcu call.
         */
        struct snd_pcm_substream __rcu *tx_substream;
        unsigned (*tx_fn)(struct xtfpga_i2s *i2s,
                          struct snd_pcm_runtime *runtime,
                          unsigned tx_ptr);
        unsigned tx_ptr; /* next frame index in the sample buffer */

        /* current fifo level estimate.
         * Doesn't have to be perfectly accurate, but must be not less than
         * the actual FIFO level in order to avoid stall on push attempt.
         */
        unsigned tx_fifo_level;

        /* FIFO level at which level interrupt occurs */
        unsigned tx_fifo_low;

        /* maximal FIFO level */
        unsigned tx_fifo_high;
};

static bool xtfpga_i2s_wr_reg(struct device *dev, unsigned int reg)
{
        return reg >= XTFPGA_I2S_CONFIG;
}

static bool xtfpga_i2s_rd_reg(struct device *dev, unsigned int reg)
{
        return reg < XTFPGA_I2S_CHAN0_DATA;
}

static bool xtfpga_i2s_volatile_reg(struct device *dev, unsigned int reg)
{
        return reg == XTFPGA_I2S_INT_STATUS;
}

static const struct regmap_config xtfpga_i2s_regmap_config = {
        .reg_bits = 32,
        .reg_stride = 4,
        .val_bits = 32,
        .max_register = XTFPGA_I2S_CHAN3_DATA,
        .writeable_reg = xtfpga_i2s_wr_reg,
        .readable_reg = xtfpga_i2s_rd_reg,
        .volatile_reg = xtfpga_i2s_volatile_reg,
        .cache_type = REGCACHE_FLAT,
};

/* Generate functions that do PIO from TX DMA area to FIFO for all supported
 * stream formats.
 * Functions will be called xtfpga_pcm_tx_<channels>x<sample bits>, e.g.
 * xtfpga_pcm_tx_2x16 for 16-bit stereo.
 *
 * FIFO consists of 32-bit words, one word per channel, always 2 channels.
 * If I2S interface is configured with smaller sample resolution, only
 * the LSB of each word is used.
 */
#define xtfpga_pcm_tx_fn(channels, sample_bits) \
static unsigned xtfpga_pcm_tx_##channels##x##sample_bits( \
        struct xtfpga_i2s *i2s, struct snd_pcm_runtime *runtime, \
        unsigned tx_ptr) \
{ \
        const u##sample_bits (*p)[channels] = \
                (void *)runtime->dma_area; \
\
        for (; i2s->tx_fifo_level < i2s->tx_fifo_high; \
             i2s->tx_fifo_level += 2) { \
                iowrite32(p[tx_ptr][0], \
                          i2s->regs + XTFPGA_I2S_CHAN0_DATA); \
                iowrite32(p[tx_ptr][channels - 1], \
                          i2s->regs + XTFPGA_I2S_CHAN0_DATA); \
                if (++tx_ptr >= runtime->buffer_size) \
                        tx_ptr = 0; \
        } \
        return tx_ptr; \
}

xtfpga_pcm_tx_fn(1, 16)
xtfpga_pcm_tx_fn(2, 16)
xtfpga_pcm_tx_fn(1, 32)
xtfpga_pcm_tx_fn(2, 32)

#undef xtfpga_pcm_tx_fn

static bool xtfpga_pcm_push_tx(struct xtfpga_i2s *i2s)
{
        struct snd_pcm_substream *tx_substream;
        bool tx_active;

        rcu_read_lock();
        tx_substream = rcu_dereference(i2s->tx_substream);
        tx_active = tx_substream && snd_pcm_running(tx_substream);
        if (tx_active) {
                unsigned tx_ptr = ACCESS_ONCE(i2s->tx_ptr);
                unsigned new_tx_ptr = i2s->tx_fn(i2s, tx_substream->runtime,
                                                 tx_ptr);

                cmpxchg(&i2s->tx_ptr, tx_ptr, new_tx_ptr);
        }
        rcu_read_unlock();

        return tx_active;
}

static void xtfpga_pcm_refill_fifo(struct xtfpga_i2s *i2s)
{
        unsigned int_status;
        unsigned i;

        regmap_read(i2s->regmap, XTFPGA_I2S_INT_STATUS,
                    &int_status);

        for (i = 0; i < 2; ++i) {
                bool tx_active = xtfpga_pcm_push_tx(i2s);

                regmap_write(i2s->regmap, XTFPGA_I2S_INT_STATUS,
                             XTFPGA_I2S_INT_VALID);
                if (tx_active)
                        regmap_read(i2s->regmap, XTFPGA_I2S_INT_STATUS,
                                    &int_status);

                if (!tx_active ||
                    !(int_status & XTFPGA_I2S_INT_LEVEL))
                        break;

                /* After the push the level IRQ is still asserted,
                 * means FIFO level is below tx_fifo_low. Estimate
                 * it as tx_fifo_low.
                 */
                i2s->tx_fifo_level = i2s->tx_fifo_low;
        }

        if (!(int_status & XTFPGA_I2S_INT_LEVEL))
                regmap_write(i2s->regmap, XTFPGA_I2S_INT_MASK,
                             XTFPGA_I2S_INT_VALID);
        else if (!(int_status & XTFPGA_I2S_INT_UNDERRUN))
                regmap_write(i2s->regmap, XTFPGA_I2S_INT_MASK,
                             XTFPGA_I2S_INT_UNDERRUN);

        if (!(int_status & XTFPGA_I2S_INT_UNDERRUN))
                regmap_update_bits(i2s->regmap, XTFPGA_I2S_CONFIG,
                                   XTFPGA_I2S_CONFIG_INT_ENABLE |
                                   XTFPGA_I2S_CONFIG_TX_ENABLE,
                                   XTFPGA_I2S_CONFIG_INT_ENABLE |
                                   XTFPGA_I2S_CONFIG_TX_ENABLE);
        else
                regmap_update_bits(i2s->regmap, XTFPGA_I2S_CONFIG,
                                   XTFPGA_I2S_CONFIG_INT_ENABLE |
                                   XTFPGA_I2S_CONFIG_TX_ENABLE, 0);
}

static irqreturn_t xtfpga_i2s_threaded_irq_handler(int irq, void *dev_id)
{
        struct xtfpga_i2s *i2s = dev_id;
        struct snd_pcm_substream *tx_substream;
        unsigned config, int_status, int_mask;

        regmap_read(i2s->regmap, XTFPGA_I2S_CONFIG, &config);
        regmap_read(i2s->regmap, XTFPGA_I2S_INT_MASK, &int_mask);
        regmap_read(i2s->regmap, XTFPGA_I2S_INT_STATUS, &int_status);

        if (!(config & XTFPGA_I2S_CONFIG_INT_ENABLE) ||
            !(int_status & int_mask & XTFPGA_I2S_INT_VALID))
                return IRQ_NONE;

        /* Update FIFO level estimate in accordance with interrupt status
         * register.
         */
        if (int_status & XTFPGA_I2S_INT_UNDERRUN) {
                i2s->tx_fifo_level = 0;
                regmap_update_bits(i2s->regmap, XTFPGA_I2S_CONFIG,
                                   XTFPGA_I2S_CONFIG_TX_ENABLE, 0);
        } else {
                /* The FIFO isn't empty, but is below tx_fifo_low. Estimate
                 * it as tx_fifo_low.
                 */
                i2s->tx_fifo_level = i2s->tx_fifo_low;
        }

        rcu_read_lock();
        tx_substream = rcu_dereference(i2s->tx_substream);

        if (tx_substream && snd_pcm_running(tx_substream)) {
                snd_pcm_period_elapsed(tx_substream);
                if (int_status & XTFPGA_I2S_INT_UNDERRUN)
                        dev_dbg_ratelimited(i2s->dev, "%s: underrun\n",
                                            __func__);
        }
        rcu_read_unlock();

        /* Refill FIFO, update allowed IRQ reasons, enable IRQ if FIFO is
         * not empty.
         */
        xtfpga_pcm_refill_fifo(i2s);

        return IRQ_HANDLED;
}

static int xtfpga_i2s_startup(struct snd_pcm_substream *substream,
                              struct snd_soc_dai *dai)
{
        struct xtfpga_i2s *i2s = snd_soc_dai_get_drvdata(dai);

        snd_soc_dai_set_dma_data(dai, substream, i2s);
        return 0;
}

static int xtfpga_i2s_hw_params(struct snd_pcm_substream *substream,
                                struct snd_pcm_hw_params *params,
                                struct snd_soc_dai *dai)
{
        struct xtfpga_i2s *i2s = snd_soc_dai_get_drvdata(dai);
        unsigned srate = params_rate(params);
        unsigned channels = params_channels(params);
        unsigned period_size = params_period_size(params);
        unsigned sample_size = snd_pcm_format_width(params_format(params));
        unsigned freq, ratio, level;
        int err;

        regmap_update_bits(i2s->regmap, XTFPGA_I2S_CONFIG,
                           XTFPGA_I2S_CONFIG_RES_MASK,
                           sample_size << XTFPGA_I2S_CONFIG_RES_BASE);

        freq = 256 * srate;
        err = clk_set_rate(i2s->clk, freq);
        if (err < 0)
                return err;

        /* ratio field of the config register controls MCLK->I2S clock
         * derivation: I2S clock = MCLK / (2 * (ratio + 2)).
         *
         * So with MCLK = 256 * sample rate ratio is 0 for 32 bit stereo
         * and 2 for 16 bit stereo.
         */
        ratio = (freq - (srate * sample_size * 8)) /
                (srate * sample_size * 4);

        regmap_update_bits(i2s->regmap, XTFPGA_I2S_CONFIG,
                           XTFPGA_I2S_CONFIG_RATIO_MASK,
                           ratio << XTFPGA_I2S_CONFIG_RATIO_BASE);

        i2s->tx_fifo_low = XTFPGA_I2S_FIFO_SIZE / 2;

        /* period_size * 2: FIFO always gets 2 samples per frame */
        for (level = 1;
             i2s->tx_fifo_low / 2 >= period_size * 2 &&
             level < (XTFPGA_I2S_CONFIG_LEVEL_MASK >>
                      XTFPGA_I2S_CONFIG_LEVEL_BASE); ++level)
                i2s->tx_fifo_low /= 2;

        i2s->tx_fifo_high = 2 * i2s->tx_fifo_low;

        regmap_update_bits(i2s->regmap, XTFPGA_I2S_CONFIG,
                           XTFPGA_I2S_CONFIG_LEVEL_MASK,
                           level << XTFPGA_I2S_CONFIG_LEVEL_BASE);

        dev_dbg(i2s->dev,
                "%s srate: %u, channels: %u, sample_size: %u, period_size: %u\n",
                __func__, srate, channels, sample_size, period_size);
        dev_dbg(i2s->dev, "%s freq: %u, ratio: %u, level: %u\n",
                __func__, freq, ratio, level);

        return 0;
}

static int xtfpga_i2s_set_fmt(struct snd_soc_dai *cpu_dai,
                              unsigned int fmt)
{
        if ((fmt & SND_SOC_DAIFMT_INV_MASK) != SND_SOC_DAIFMT_NB_NF)
                return -EINVAL;
        if ((fmt & SND_SOC_DAIFMT_MASTER_MASK) != SND_SOC_DAIFMT_CBS_CFS)
                return -EINVAL;
        if ((fmt & SND_SOC_DAIFMT_FORMAT_MASK) != SND_SOC_DAIFMT_I2S)
                return -EINVAL;

        return 0;
}

/* PCM */

static const struct snd_pcm_hardware xtfpga_pcm_hardware = {
        .info = SNDRV_PCM_INFO_INTERLEAVED |
                SNDRV_PCM_INFO_MMAP_VALID |
                SNDRV_PCM_INFO_BLOCK_TRANSFER,
        .formats                = SNDRV_PCM_FMTBIT_S16_LE |
                                  SNDRV_PCM_FMTBIT_S32_LE,
        .channels_min           = 1,
        .channels_max           = 2,
        .period_bytes_min       = 2,
        .period_bytes_max       = XTFPGA_I2S_FIFO_SIZE / 2 * 8,
        .periods_min            = 2,
        .periods_max            = XTFPGA_I2S_FIFO_SIZE * 8 / 2,
        .buffer_bytes_max       = XTFPGA_I2S_FIFO_SIZE * 8,
        .fifo_size              = 16,
};

static int xtfpga_pcm_open(struct snd_pcm_substream *substream)
{
        struct snd_pcm_runtime *runtime = substream->runtime;
        struct snd_soc_pcm_runtime *rtd = substream->private_data;
        void *p;

        snd_soc_set_runtime_hwparams(substream, &xtfpga_pcm_hardware);
        p = snd_soc_dai_get_dma_data(rtd->cpu_dai, substream);
        runtime->private_data = p;

        return 0;
}

static int xtfpga_pcm_close(struct snd_pcm_substream *substream)
{
        synchronize_rcu();
        return 0;
}

static int xtfpga_pcm_hw_params(struct snd_pcm_substream *substream,
                                struct snd_pcm_hw_params *hw_params)
{
        int ret;
        struct snd_pcm_runtime *runtime = substream->runtime;
        struct xtfpga_i2s *i2s = runtime->private_data;
        unsigned channels = params_channels(hw_params);

        switch (channels) {
        case 1:
        case 2:
                break;

        default:
                return -EINVAL;

        }

        switch (params_format(hw_params)) {
        case SNDRV_PCM_FORMAT_S16_LE:
                i2s->tx_fn = (channels == 1) ?
                        xtfpga_pcm_tx_1x16 :
                        xtfpga_pcm_tx_2x16;
                break;

        case SNDRV_PCM_FORMAT_S32_LE:
                i2s->tx_fn = (channels == 1) ?
                        xtfpga_pcm_tx_1x32 :
                        xtfpga_pcm_tx_2x32;
                break;

        default:
                return -EINVAL;
        }

        ret = snd_pcm_lib_malloc_pages(substream,
                                       params_buffer_bytes(hw_params));
        return ret;
}

static int xtfpga_pcm_trigger(struct snd_pcm_substream *substream, int cmd)
{
        int ret = 0;
        struct snd_pcm_runtime *runtime = substream->runtime;
        struct xtfpga_i2s *i2s = runtime->private_data;

        switch (cmd) {
        case SNDRV_PCM_TRIGGER_START:
        case SNDRV_PCM_TRIGGER_RESUME:
        case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:
                ACCESS_ONCE(i2s->tx_ptr) = 0;
                rcu_assign_pointer(i2s->tx_substream, substream);
                xtfpga_pcm_refill_fifo(i2s);
                break;

        case SNDRV_PCM_TRIGGER_STOP:
        case SNDRV_PCM_TRIGGER_SUSPEND:
        case SNDRV_PCM_TRIGGER_PAUSE_PUSH:
                rcu_assign_pointer(i2s->tx_substream, NULL);
                break;

        default:
                ret = -EINVAL;
                break;
        }
        return ret;
}

static snd_pcm_uframes_t xtfpga_pcm_pointer(struct snd_pcm_substream *substream)
{
        struct snd_pcm_runtime *runtime = substream->runtime;
        struct xtfpga_i2s *i2s = runtime->private_data;
        snd_pcm_uframes_t pos = ACCESS_ONCE(i2s->tx_ptr);

        return pos < runtime->buffer_size ? pos : 0;
}

static int xtfpga_pcm_new(struct snd_soc_pcm_runtime *rtd)
{
        struct snd_card *card = rtd->card->snd_card;
        size_t size = xtfpga_pcm_hardware.buffer_bytes_max;

        return snd_pcm_lib_preallocate_pages_for_all(rtd->pcm,
                                                     SNDRV_DMA_TYPE_DEV,
                                                     card->dev, size, size);
}

static const struct snd_pcm_ops xtfpga_pcm_ops = {
        .open           = xtfpga_pcm_open,
        .close          = xtfpga_pcm_close,
        .ioctl          = snd_pcm_lib_ioctl,
        .hw_params      = xtfpga_pcm_hw_params,
        .trigger        = xtfpga_pcm_trigger,
        .pointer        = xtfpga_pcm_pointer,
};

static const struct snd_soc_platform_driver xtfpga_soc_platform = {
        .pcm_new        = xtfpga_pcm_new,
        .ops            = &xtfpga_pcm_ops,
};

static const struct snd_soc_component_driver xtfpga_i2s_component = {
        .name           = DRV_NAME,
};

static const struct snd_soc_dai_ops xtfpga_i2s_dai_ops = {
        .startup        = xtfpga_i2s_startup,
        .hw_params      = xtfpga_i2s_hw_params,
        .set_fmt        = xtfpga_i2s_set_fmt,
};

static struct snd_soc_dai_driver xtfpga_i2s_dai[] = {
        {
                .name = "xtfpga-i2s",
                .id = 0,
                .playback = {
                        .channels_min = 1,
                        .channels_max = 2,
                        .rates = SNDRV_PCM_RATE_8000_96000,
                        .formats = SNDRV_PCM_FMTBIT_S16_LE |
                                   SNDRV_PCM_FMTBIT_S32_LE,
                },
                .ops = &xtfpga_i2s_dai_ops,
        },
};

static int xtfpga_i2s_runtime_suspend(struct device *dev)
{
        struct xtfpga_i2s *i2s = dev_get_drvdata(dev);

        clk_disable_unprepare(i2s->clk);
        return 0;
}

static int xtfpga_i2s_runtime_resume(struct device *dev)
{
        struct xtfpga_i2s *i2s = dev_get_drvdata(dev);
        int ret;

        ret = clk_prepare_enable(i2s->clk);
        if (ret) {
                dev_err(dev, "clk_prepare_enable failed: %d\n", ret);
                return ret;
        }
        return 0;
}

static int xtfpga_i2s_probe(struct platform_device *pdev)
{
        struct xtfpga_i2s *i2s;
        struct resource *mem;
        int err, irq;

        i2s = devm_kzalloc(&pdev->dev, sizeof(*i2s), GFP_KERNEL);
        if (!i2s) {
                err = -ENOMEM;
                goto err;
        }
        platform_set_drvdata(pdev, i2s);
        i2s->dev = &pdev->dev;
        dev_dbg(&pdev->dev, "dev: %p, i2s: %p\n", &pdev->dev, i2s);

        mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        i2s->regs = devm_ioremap_resource(&pdev->dev, mem);
        if (IS_ERR(i2s->regs)) {
                err = PTR_ERR(i2s->regs);
                goto err;
        }

        i2s->regmap = devm_regmap_init_mmio(&pdev->dev, i2s->regs,
                                            &xtfpga_i2s_regmap_config);
        if (IS_ERR(i2s->regmap)) {
                dev_err(&pdev->dev, "regmap init failed\n");
                err = PTR_ERR(i2s->regmap);
                goto err;
        }

        i2s->clk = devm_clk_get(&pdev->dev, NULL);
        if (IS_ERR(i2s->clk)) {
                dev_err(&pdev->dev, "couldn't get clock\n");
                err = PTR_ERR(i2s->clk);
                goto err;
        }

        regmap_write(i2s->regmap, XTFPGA_I2S_CONFIG,
                     (0x1 << XTFPGA_I2S_CONFIG_CHANNEL_BASE));
        regmap_write(i2s->regmap, XTFPGA_I2S_INT_STATUS, XTFPGA_I2S_INT_VALID);
        regmap_write(i2s->regmap, XTFPGA_I2S_INT_MASK, XTFPGA_I2S_INT_UNDERRUN);

        irq = platform_get_irq(pdev, 0);
        if (irq < 0) {
                dev_err(&pdev->dev, "No IRQ resource\n");
                err = irq;
                goto err;
        }
        err = devm_request_threaded_irq(&pdev->dev, irq, NULL,
                                        xtfpga_i2s_threaded_irq_handler,
                                        IRQF_SHARED | IRQF_ONESHOT,
                                        pdev->name, i2s);
        if (err < 0) {
                dev_err(&pdev->dev, "request_irq failed\n");
                goto err;
        }

        err = snd_soc_register_platform(&pdev->dev, &xtfpga_soc_platform);
        if (err < 0) {
                dev_err(&pdev->dev, "couldn't register platform\n");
                goto err;
        }
        err = devm_snd_soc_register_component(&pdev->dev,
                                              &xtfpga_i2s_component,
                                              xtfpga_i2s_dai,
                                              ARRAY_SIZE(xtfpga_i2s_dai));
        if (err < 0) {
                dev_err(&pdev->dev, "couldn't register component\n");
                goto err_unregister_platform;
        }

        pm_runtime_enable(&pdev->dev);
        if (!pm_runtime_enabled(&pdev->dev)) {
                err = xtfpga_i2s_runtime_resume(&pdev->dev);
                if (err)
                        goto err_pm_disable;
        }
        return 0;

err_pm_disable:
        pm_runtime_disable(&pdev->dev);
err_unregister_platform:
        snd_soc_unregister_platform(&pdev->dev);
err:
        dev_err(&pdev->dev, "%s: err = %d\n", __func__, err);
        return err;
}

static int xtfpga_i2s_remove(struct platform_device *pdev)
{
        struct xtfpga_i2s *i2s = dev_get_drvdata(&pdev->dev);

        snd_soc_unregister_platform(&pdev->dev);
        if (i2s->regmap && !IS_ERR(i2s->regmap)) {
                regmap_write(i2s->regmap, XTFPGA_I2S_CONFIG, 0);
                regmap_write(i2s->regmap, XTFPGA_I2S_INT_MASK, 0);
                regmap_write(i2s->regmap, XTFPGA_I2S_INT_STATUS,
                             XTFPGA_I2S_INT_VALID);
        }
        pm_runtime_disable(&pdev->dev);
        if (!pm_runtime_status_suspended(&pdev->dev))
                xtfpga_i2s_runtime_suspend(&pdev->dev);
        return 0;
}

#ifdef CONFIG_OF
static const struct of_device_id xtfpga_i2s_of_match[] = {
        { .compatible = "cdns,xtfpga-i2s", },
        {},
};
MODULE_DEVICE_TABLE(of, xtfpga_i2s_of_match);
#endif

static const struct dev_pm_ops xtfpga_i2s_pm_ops = {
        SET_RUNTIME_PM_OPS(xtfpga_i2s_runtime_suspend,
                           xtfpga_i2s_runtime_resume, NULL)
};

static struct platform_driver xtfpga_i2s_driver = {
        .probe   = xtfpga_i2s_probe,
        .remove  = xtfpga_i2s_remove,
        .driver  = {
                .name = "xtfpga-i2s",
                .of_match_table = of_match_ptr(xtfpga_i2s_of_match),
                .pm = &xtfpga_i2s_pm_ops,
        },
};

module_platform_driver(xtfpga_i2s_driver);

MODULE_AUTHOR("Max Filippov <jcmvbkbc@gmail.com>");
MODULE_DESCRIPTION("xtfpga I2S controller driver");
MODULE_LICENSE("GPL v2");