// SPDX-License-Identifier: GPL-2.0-only
/*
 * Driver for Atmel I2S controller
 *
 * Copyright (C) 2015 Atmel Corporation
 *
 * Author: Cyrille Pitchen <cyrille.pitchen@atmel.com>
 */

#include <linux/init.h>
#include <linux/module.h>
#include <linux/device.h>
#include <linux/slab.h>
#include <linux/delay.h>
#include <linux/io.h>
#include <linux/clk.h>
#include <linux/mfd/syscon.h>

#include <sound/core.h>
#include <sound/pcm.h>
#include <sound/pcm_params.h>
#include <sound/initval.h>
#include <sound/soc.h>
#include <sound/dmaengine_pcm.h>

#define ATMEL_I2SC_MAX_TDM_CHANNELS     8

/*
 * ---- I2S Controller Register map ----
 */
#define ATMEL_I2SC_CR           0x0000  /* Control Register */
#define ATMEL_I2SC_MR           0x0004  /* Mode Register */
#define ATMEL_I2SC_SR           0x0008  /* Status Register */
#define ATMEL_I2SC_SCR          0x000c  /* Status Clear Register */
#define ATMEL_I2SC_SSR          0x0010  /* Status Set Register */
#define ATMEL_I2SC_IER          0x0014  /* Interrupt Enable Register */
#define ATMEL_I2SC_IDR          0x0018  /* Interrupt Disable Register */
#define ATMEL_I2SC_IMR          0x001c  /* Interrupt Mask Register */
#define ATMEL_I2SC_RHR          0x0020  /* Receiver Holding Register */
#define ATMEL_I2SC_THR          0x0024  /* Transmitter Holding Register */
#define ATMEL_I2SC_VERSION      0x0028  /* Version Register */

/*
 * ---- Control Register (Write-only) ----
 */
#define ATMEL_I2SC_CR_RXEN      BIT(0)  /* Receiver Enable */
#define ATMEL_I2SC_CR_RXDIS     BIT(1)  /* Receiver Disable */
#define ATMEL_I2SC_CR_CKEN      BIT(2)  /* Clock Enable */
#define ATMEL_I2SC_CR_CKDIS     BIT(3)  /* Clock Disable */
#define ATMEL_I2SC_CR_TXEN      BIT(4)  /* Transmitter Enable */
#define ATMEL_I2SC_CR_TXDIS     BIT(5)  /* Transmitter Disable */
#define ATMEL_I2SC_CR_SWRST     BIT(7)  /* Software Reset */

/*
 * ---- Mode Register (Read/Write) ----
 */
#define ATMEL_I2SC_MR_MODE_MASK         GENMASK(0, 0)
#define ATMEL_I2SC_MR_MODE_SLAVE        (0 << 0)
#define ATMEL_I2SC_MR_MODE_MASTER       (1 << 0)

#define ATMEL_I2SC_MR_DATALENGTH_MASK           GENMASK(4, 2)
#define ATMEL_I2SC_MR_DATALENGTH_32_BITS        (0 << 2)
#define ATMEL_I2SC_MR_DATALENGTH_24_BITS        (1 << 2)
#define ATMEL_I2SC_MR_DATALENGTH_20_BITS        (2 << 2)
#define ATMEL_I2SC_MR_DATALENGTH_18_BITS        (3 << 2)
#define ATMEL_I2SC_MR_DATALENGTH_16_BITS        (4 << 2)
#define ATMEL_I2SC_MR_DATALENGTH_16_BITS_COMPACT        (5 << 2)
#define ATMEL_I2SC_MR_DATALENGTH_8_BITS         (6 << 2)
#define ATMEL_I2SC_MR_DATALENGTH_8_BITS_COMPACT (7 << 2)

#define ATMEL_I2SC_MR_FORMAT_MASK       GENMASK(7, 6)
#define ATMEL_I2SC_MR_FORMAT_I2S        (0 << 6)
#define ATMEL_I2SC_MR_FORMAT_LJ         (1 << 6)  /* Left Justified */
#define ATMEL_I2SC_MR_FORMAT_TDM        (2 << 6)
#define ATMEL_I2SC_MR_FORMAT_TDMLJ      (3 << 6)

/* Left audio samples duplicated to right audio channel */
#define ATMEL_I2SC_MR_RXMONO            BIT(8)

/* Receiver uses one DMA channel ... */
#define ATMEL_I2SC_MR_RXDMA_MASK        GENMASK(9, 9)
#define ATMEL_I2SC_MR_RXDMA_SINGLE      (0 << 9)  /* for all audio channels */
#define ATMEL_I2SC_MR_RXDMA_MULTIPLE    (1 << 9)  /* per audio channel */

/* I2SDO output of I2SC is internally connected to I2SDI input */
#define ATMEL_I2SC_MR_RXLOOP            BIT(10)

/* Left audio samples duplicated to right audio channel */
#define ATMEL_I2SC_MR_TXMONO            BIT(12)

/* Transmitter uses one DMA channel ... */
#define ATMEL_I2SC_MR_TXDMA_MASK        GENMASK(13, 13)
#define ATMEL_I2SC_MR_TXDMA_SINGLE      (0 << 13)  /* for all audio channels */
#define ATMEL_I2SC_MR_TXDME_MULTIPLE    (1 << 13)  /* per audio channel */

/* x sample transmitted when underrun */
#define ATMEL_I2SC_MR_TXSAME_MASK       GENMASK(14, 14)
#define ATMEL_I2SC_MR_TXSAME_ZERO       (0 << 14)  /* Zero sample */
#define ATMEL_I2SC_MR_TXSAME_PREVIOUS   (1 << 14)  /* Previous sample */

/* Audio Clock to I2SC Master Clock ratio */
#define ATMEL_I2SC_MR_IMCKDIV_MASK      GENMASK(21, 16)
#define ATMEL_I2SC_MR_IMCKDIV(div) \
        (((div) << 16) & ATMEL_I2SC_MR_IMCKDIV_MASK)

/* Master Clock to fs ratio */
#define ATMEL_I2SC_MR_IMCKFS_MASK       GENMASK(29, 24)
#define ATMEL_I2SC_MR_IMCKFS(fs) \
        (((fs) << 24) & ATMEL_I2SC_MR_IMCKFS_MASK)

/* Master Clock mode */
#define ATMEL_I2SC_MR_IMCKMODE_MASK     GENMASK(30, 30)
/* 0: No master clock generated (selected clock drives I2SCK pin) */
#define ATMEL_I2SC_MR_IMCKMODE_I2SCK    (0 << 30)
/* 1: master clock generated (internally generated clock drives I2SMCK pin) */
#define ATMEL_I2SC_MR_IMCKMODE_I2SMCK   (1 << 30)

/* Slot Width */
/* 0: slot is 32 bits wide for DATALENGTH = 18/20/24 bits. */
/* 1: slot is 24 bits wide for DATALENGTH = 18/20/24 bits. */
#define ATMEL_I2SC_MR_IWS               BIT(31)

/*
 * ---- Status Registers ----
 */
#define ATMEL_I2SC_SR_RXEN      BIT(0)  /* Receiver Enabled */
#define ATMEL_I2SC_SR_RXRDY     BIT(1)  /* Receive Ready */
#define ATMEL_I2SC_SR_RXOR      BIT(2)  /* Receive Overrun */

#define ATMEL_I2SC_SR_TXEN      BIT(4)  /* Transmitter Enabled */
#define ATMEL_I2SC_SR_TXRDY     BIT(5)  /* Transmit Ready */
#define ATMEL_I2SC_SR_TXUR      BIT(6)  /* Transmit Underrun */

/* Receive Overrun Channel */
#define ATMEL_I2SC_SR_RXORCH_MASK       GENMASK(15, 8)
#define ATMEL_I2SC_SR_RXORCH(ch)        (1 << (((ch) & 0x7) + 8))

/* Transmit Underrun Channel */
#define ATMEL_I2SC_SR_TXURCH_MASK       GENMASK(27, 20)
#define ATMEL_I2SC_SR_TXURCH(ch)        (1 << (((ch) & 0x7) + 20))

/*
 * ---- Interrupt Enable/Disable/Mask Registers ----
 */
#define ATMEL_I2SC_INT_RXRDY    ATMEL_I2SC_SR_RXRDY
#define ATMEL_I2SC_INT_RXOR     ATMEL_I2SC_SR_RXOR
#define ATMEL_I2SC_INT_TXRDY    ATMEL_I2SC_SR_TXRDY
#define ATMEL_I2SC_INT_TXUR     ATMEL_I2SC_SR_TXUR

static const struct regmap_config atmel_i2s_regmap_config = {
        .reg_bits = 32,
        .reg_stride = 4,
        .val_bits = 32,
        .max_register = ATMEL_I2SC_VERSION,
};

struct atmel_i2s_gck_param {
        int             fs;
        unsigned long   mck;
        int             imckdiv;
        int             imckfs;
};

#define I2S_MCK_12M288          12288000UL
#define I2S_MCK_11M2896         11289600UL

/* mck = (32 * (imckfs+1) / (imckdiv+1)) * fs */
static const struct atmel_i2s_gck_param gck_params[] = {
        /* mck = 12.288MHz */
        {  8000, I2S_MCK_12M288, 0, 47},        /* mck = 1536 fs */
        { 16000, I2S_MCK_12M288, 1, 47},        /* mck =  768 fs */
        { 24000, I2S_MCK_12M288, 3, 63},        /* mck =  512 fs */
        { 32000, I2S_MCK_12M288, 3, 47},        /* mck =  384 fs */
        { 48000, I2S_MCK_12M288, 7, 63},        /* mck =  256 fs */
        { 64000, I2S_MCK_12M288, 7, 47},        /* mck =  192 fs */
        { 96000, I2S_MCK_12M288, 7, 31},        /* mck =  128 fs */
        {192000, I2S_MCK_12M288, 7, 15},        /* mck =   64 fs */

        /* mck = 11.2896MHz */
        { 11025, I2S_MCK_11M2896, 1, 63},       /* mck = 1024 fs */
        { 22050, I2S_MCK_11M2896, 3, 63},       /* mck =  512 fs */
        { 44100, I2S_MCK_11M2896, 7, 63},       /* mck =  256 fs */
        { 88200, I2S_MCK_11M2896, 7, 31},       /* mck =  128 fs */
        {176400, I2S_MCK_11M2896, 7, 15},       /* mck =   64 fs */
};

struct atmel_i2s_dev;

struct atmel_i2s_caps {
        int     (*mck_init)(struct atmel_i2s_dev *, struct device_node *np);
};

struct atmel_i2s_dev {
        struct device                           *dev;
        struct regmap                           *regmap;
        struct clk                              *pclk;
        struct clk                              *gclk;
        struct snd_dmaengine_dai_dma_data       playback;
        struct snd_dmaengine_dai_dma_data       capture;
        unsigned int                            fmt;
        const struct atmel_i2s_gck_param        *gck_param;
        const struct atmel_i2s_caps             *caps;
};

static irqreturn_t atmel_i2s_interrupt(int irq, void *dev_id)
{
        struct atmel_i2s_dev *dev = dev_id;
        unsigned int sr, imr, pending, ch, mask;
        irqreturn_t ret = IRQ_NONE;

        regmap_read(dev->regmap, ATMEL_I2SC_SR, &sr);
        regmap_read(dev->regmap, ATMEL_I2SC_IMR, &imr);
        pending = sr & imr;

        if (!pending)
                return IRQ_NONE;

        if (pending & ATMEL_I2SC_INT_RXOR) {
                mask = ATMEL_I2SC_SR_RXOR;

                for (ch = 0; ch < ATMEL_I2SC_MAX_TDM_CHANNELS; ++ch) {
                        if (sr & ATMEL_I2SC_SR_RXORCH(ch)) {
                                mask |= ATMEL_I2SC_SR_RXORCH(ch);
                                dev_err(dev->dev,
                                        "RX overrun on channel %d\n", ch);
                        }
                }
                regmap_write(dev->regmap, ATMEL_I2SC_SCR, mask);
                ret = IRQ_HANDLED;
        }

        if (pending & ATMEL_I2SC_INT_TXUR) {
                mask = ATMEL_I2SC_SR_TXUR;

                for (ch = 0; ch < ATMEL_I2SC_MAX_TDM_CHANNELS; ++ch) {
                        if (sr & ATMEL_I2SC_SR_TXURCH(ch)) {
                                mask |= ATMEL_I2SC_SR_TXURCH(ch);
                                dev_err(dev->dev,
                                        "TX underrun on channel %d\n", ch);
                        }
                }
                regmap_write(dev->regmap, ATMEL_I2SC_SCR, mask);
                ret = IRQ_HANDLED;
        }

        return ret;
}

#define ATMEL_I2S_RATES         SNDRV_PCM_RATE_8000_192000

#define ATMEL_I2S_FORMATS       (SNDRV_PCM_FMTBIT_S8 |          \
                                 SNDRV_PCM_FMTBIT_S16_LE |      \
                                 SNDRV_PCM_FMTBIT_S18_3LE |     \
                                 SNDRV_PCM_FMTBIT_S20_3LE |     \
                                 SNDRV_PCM_FMTBIT_S24_3LE |     \
                                 SNDRV_PCM_FMTBIT_S24_LE |      \
                                 SNDRV_PCM_FMTBIT_S32_LE)

static int atmel_i2s_set_dai_fmt(struct snd_soc_dai *dai, unsigned int fmt)
{
        struct atmel_i2s_dev *dev = snd_soc_dai_get_drvdata(dai);

        dev->fmt = fmt;
        return 0;
}

static int atmel_i2s_prepare(struct snd_pcm_substream *substream,
                             struct snd_soc_dai *dai)
{
        struct atmel_i2s_dev *dev = snd_soc_dai_get_drvdata(dai);
        bool is_playback = (substream->stream == SNDRV_PCM_STREAM_PLAYBACK);
        unsigned int rhr, sr = 0;

        if (is_playback) {
                regmap_read(dev->regmap, ATMEL_I2SC_SR, &sr);
                if (sr & ATMEL_I2SC_SR_RXRDY) {
                        /*
                         * The RX Ready flag should not be set. However if here,
                         * we flush (read) the Receive Holding Register to start
                         * from a clean state.
                         */
                        dev_dbg(dev->dev, "RXRDY is set\n");
                        regmap_read(dev->regmap, ATMEL_I2SC_RHR, &rhr);
                }
        }

        return 0;
}

static int atmel_i2s_get_gck_param(struct atmel_i2s_dev *dev, int fs)
{
        int i, best;

        if (!dev->gclk) {
                dev_err(dev->dev, "cannot generate the I2S Master Clock\n");
                return -EINVAL;
        }

        /*
         * Find the best possible settings to generate the I2S Master Clock
         * from the PLL Audio.
         */
        dev->gck_param = NULL;
        best = INT_MAX;
        for (i = 0; i < ARRAY_SIZE(gck_params); ++i) {
                const struct atmel_i2s_gck_param *gck_param = &gck_params[i];
                int val = abs(fs - gck_param->fs);

                if (val < best) {
                        best = val;
                        dev->gck_param = gck_param;
                }
        }

        return 0;
}

static int atmel_i2s_hw_params(struct snd_pcm_substream *substream,
                               struct snd_pcm_hw_params *params,
                               struct snd_soc_dai *dai)
{
        struct atmel_i2s_dev *dev = snd_soc_dai_get_drvdata(dai);
        bool is_playback = (substream->stream == SNDRV_PCM_STREAM_PLAYBACK);
        unsigned int mr = 0;
        int ret;

        switch (dev->fmt & SND_SOC_DAIFMT_FORMAT_MASK) {
        case SND_SOC_DAIFMT_I2S:
                mr |= ATMEL_I2SC_MR_FORMAT_I2S;
                break;

        default:
                dev_err(dev->dev, "unsupported bus format\n");
                return -EINVAL;
        }

        switch (dev->fmt & SND_SOC_DAIFMT_MASTER_MASK) {
        case SND_SOC_DAIFMT_CBS_CFS:
                /* codec is slave, so cpu is master */
                mr |= ATMEL_I2SC_MR_MODE_MASTER;
                ret = atmel_i2s_get_gck_param(dev, params_rate(params));
                if (ret)
                        return ret;
                break;

        case SND_SOC_DAIFMT_CBM_CFM:
                /* codec is master, so cpu is slave */
                mr |= ATMEL_I2SC_MR_MODE_SLAVE;
                dev->gck_param = NULL;
                break;

        default:
                dev_err(dev->dev, "unsupported master/slave mode\n");
                return -EINVAL;
        }

        switch (params_channels(params)) {
        case 1:
                if (is_playback)
                        mr |= ATMEL_I2SC_MR_TXMONO;
                else
                        mr |= ATMEL_I2SC_MR_RXMONO;
                break;
        case 2:
                break;
        default:
                dev_err(dev->dev, "unsupported number of audio channels\n");
                return -EINVAL;
        }

        switch (params_format(params)) {
        case SNDRV_PCM_FORMAT_S8:
                mr |= ATMEL_I2SC_MR_DATALENGTH_8_BITS;
                break;

        case SNDRV_PCM_FORMAT_S16_LE:
                mr |= ATMEL_I2SC_MR_DATALENGTH_16_BITS;
                break;

        case SNDRV_PCM_FORMAT_S18_3LE:
                mr |= ATMEL_I2SC_MR_DATALENGTH_18_BITS | ATMEL_I2SC_MR_IWS;
                break;

        case SNDRV_PCM_FORMAT_S20_3LE:
                mr |= ATMEL_I2SC_MR_DATALENGTH_20_BITS | ATMEL_I2SC_MR_IWS;
                break;

        case SNDRV_PCM_FORMAT_S24_3LE:
                mr |= ATMEL_I2SC_MR_DATALENGTH_24_BITS | ATMEL_I2SC_MR_IWS;
                break;

        case SNDRV_PCM_FORMAT_S24_LE:
                mr |= ATMEL_I2SC_MR_DATALENGTH_24_BITS;
                break;

        case SNDRV_PCM_FORMAT_S32_LE:
                mr |= ATMEL_I2SC_MR_DATALENGTH_32_BITS;
                break;

        default:
                dev_err(dev->dev, "unsupported size/endianness for audio samples\n");
                return -EINVAL;
        }

        return regmap_write(dev->regmap, ATMEL_I2SC_MR, mr);
}

static int atmel_i2s_switch_mck_generator(struct atmel_i2s_dev *dev,
                                          bool enabled)
{
        unsigned int mr, mr_mask;
        unsigned long gclk_rate;
        int ret;

        mr = 0;
        mr_mask = (ATMEL_I2SC_MR_IMCKDIV_MASK |
                   ATMEL_I2SC_MR_IMCKFS_MASK |
                   ATMEL_I2SC_MR_IMCKMODE_MASK);

        if (!enabled) {
                /* Disable the I2S Master Clock generator. */
                ret = regmap_write(dev->regmap, ATMEL_I2SC_CR,
                                   ATMEL_I2SC_CR_CKDIS);
                if (ret)
                        return ret;

                /* Reset the I2S Master Clock generator settings. */
                ret = regmap_update_bits(dev->regmap, ATMEL_I2SC_MR,
                                         mr_mask, mr);
                if (ret)
                        return ret;

                /* Disable/unprepare the PMC generated clock. */
                clk_disable_unprepare(dev->gclk);

                return 0;
        }

        if (!dev->gck_param)
                return -EINVAL;

        gclk_rate = dev->gck_param->mck * (dev->gck_param->imckdiv + 1);

        ret = clk_set_rate(dev->gclk, gclk_rate);
        if (ret)
                return ret;

        ret = clk_prepare_enable(dev->gclk);
        if (ret)
                return ret;

        /* Update the Mode Register to generate the I2S Master Clock. */
        mr |= ATMEL_I2SC_MR_IMCKDIV(dev->gck_param->imckdiv);
        mr |= ATMEL_I2SC_MR_IMCKFS(dev->gck_param->imckfs);
        mr |= ATMEL_I2SC_MR_IMCKMODE_I2SMCK;
        ret = regmap_update_bits(dev->regmap, ATMEL_I2SC_MR, mr_mask, mr);
        if (ret)
                return ret;

        /* Finally enable the I2S Master Clock generator. */
        return regmap_write(dev->regmap, ATMEL_I2SC_CR,
                            ATMEL_I2SC_CR_CKEN);
}

static int atmel_i2s_trigger(struct snd_pcm_substream *substream, int cmd,
                             struct snd_soc_dai *dai)
{
        struct atmel_i2s_dev *dev = snd_soc_dai_get_drvdata(dai);
        bool is_playback = (substream->stream == SNDRV_PCM_STREAM_PLAYBACK);
        bool is_master, mck_enabled;
        unsigned int cr, mr;
        int err;

        switch (cmd) {
        case SNDRV_PCM_TRIGGER_START:
        case SNDRV_PCM_TRIGGER_RESUME:
        case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:
                cr = is_playback ? ATMEL_I2SC_CR_TXEN : ATMEL_I2SC_CR_RXEN;
                mck_enabled = true;
                break;
        case SNDRV_PCM_TRIGGER_STOP:
        case SNDRV_PCM_TRIGGER_SUSPEND:
        case SNDRV_PCM_TRIGGER_PAUSE_PUSH:
                cr = is_playback ? ATMEL_I2SC_CR_TXDIS : ATMEL_I2SC_CR_RXDIS;
                mck_enabled = false;
                break;
        default:
                return -EINVAL;
        }

        /* Read the Mode Register to retrieve the master/slave state. */
        err = regmap_read(dev->regmap, ATMEL_I2SC_MR, &mr);
        if (err)
                return err;
        is_master = (mr & ATMEL_I2SC_MR_MODE_MASK) == ATMEL_I2SC_MR_MODE_MASTER;

        /* If master starts, enable the audio clock. */
        if (is_master && mck_enabled)
                err = atmel_i2s_switch_mck_generator(dev, true);
        if (err)
                return err;

        err = regmap_write(dev->regmap, ATMEL_I2SC_CR, cr);
        if (err)
                return err;

        /* If master stops, disable the audio clock. */
        if (is_master && !mck_enabled)
                err = atmel_i2s_switch_mck_generator(dev, false);

        return err;
}

static const struct snd_soc_dai_ops atmel_i2s_dai_ops = {
        .prepare        = atmel_i2s_prepare,
        .trigger        = atmel_i2s_trigger,
        .hw_params      = atmel_i2s_hw_params,
        .set_fmt        = atmel_i2s_set_dai_fmt,
};

static int atmel_i2s_dai_probe(struct snd_soc_dai *dai)
{
        struct atmel_i2s_dev *dev = snd_soc_dai_get_drvdata(dai);

        snd_soc_dai_init_dma_data(dai, &dev->playback, &dev->capture);
        return 0;
}

static struct snd_soc_dai_driver atmel_i2s_dai = {
        .probe  = atmel_i2s_dai_probe,
        .playback = {
                .channels_min = 1,
                .channels_max = 2,
                .rates = ATMEL_I2S_RATES,
                .formats = ATMEL_I2S_FORMATS,
        },
        .capture = {
                .channels_min = 1,
                .channels_max = 2,
                .rates = ATMEL_I2S_RATES,
                .formats = ATMEL_I2S_FORMATS,
        },
        .ops = &atmel_i2s_dai_ops,
        .symmetric_rate = 1,
};

static const struct snd_soc_component_driver atmel_i2s_component = {
        .name   = "atmel-i2s",
};

static int atmel_i2s_sama5d2_mck_init(struct atmel_i2s_dev *dev,
                                      struct device_node *np)
{
        struct clk *muxclk;
        int err;

        if (!dev->gclk)
                return 0;

        /* muxclk is optional, so we return error for probe defer only */
        muxclk = devm_clk_get(dev->dev, "muxclk");
        if (IS_ERR(muxclk)) {
                err = PTR_ERR(muxclk);
                if (err == -EPROBE_DEFER)
                        return -EPROBE_DEFER;
                dev_dbg(dev->dev,
                        "failed to get the I2S clock control: %d\n", err);
                return 0;
        }

        return clk_set_parent(muxclk, dev->gclk);
}

static const struct atmel_i2s_caps atmel_i2s_sama5d2_caps = {
        .mck_init = atmel_i2s_sama5d2_mck_init,
};

static const struct of_device_id atmel_i2s_dt_ids[] = {
        {
                .compatible = "atmel,sama5d2-i2s",
                .data = (void *)&atmel_i2s_sama5d2_caps,
        },

        { /* sentinel */ }
};

MODULE_DEVICE_TABLE(of, atmel_i2s_dt_ids);

static int atmel_i2s_probe(struct platform_device *pdev)
{
        struct device_node *np = pdev->dev.of_node;
        const struct of_device_id *match;
        struct atmel_i2s_dev *dev;
        struct resource *mem;
        struct regmap *regmap;
        void __iomem *base;
        int irq;
        int err = -ENXIO;
        unsigned int pcm_flags = 0;
        unsigned int version;

        /* Get memory for driver data. */
        dev = devm_kzalloc(&pdev->dev, sizeof(*dev), GFP_KERNEL);
        if (!dev)
                return -ENOMEM;

        /* Get hardware capabilities. */
        match = of_match_node(atmel_i2s_dt_ids, np);
        if (match)
                dev->caps = match->data;

        /* Map I/O registers. */
        mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        base = devm_ioremap_resource(&pdev->dev, mem);
        if (IS_ERR(base))
                return PTR_ERR(base);

        regmap = devm_regmap_init_mmio(&pdev->dev, base,
                                       &atmel_i2s_regmap_config);
        if (IS_ERR(regmap))
                return PTR_ERR(regmap);

        /* Request IRQ. */
        irq = platform_get_irq(pdev, 0);
        if (irq < 0)
                return irq;

        err = devm_request_irq(&pdev->dev, irq, atmel_i2s_interrupt, 0,
                               dev_name(&pdev->dev), dev);
        if (err)
                return err;

        /* Get the peripheral clock. */
        dev->pclk = devm_clk_get(&pdev->dev, "pclk");
        if (IS_ERR(dev->pclk)) {
                err = PTR_ERR(dev->pclk);
                dev_err(&pdev->dev,
                        "failed to get the peripheral clock: %d\n", err);
                return err;
        }

        /* Get audio clock to generate the I2S Master Clock (I2S_MCK) */
        dev->gclk = devm_clk_get(&pdev->dev, "gclk");
        if (IS_ERR(dev->gclk)) {
                if (PTR_ERR(dev->gclk) == -EPROBE_DEFER)
                        return -EPROBE_DEFER;
                /* Master Mode not supported */
                dev->gclk = NULL;
        }
        dev->dev = &pdev->dev;
        dev->regmap = regmap;
        platform_set_drvdata(pdev, dev);

        /* Do hardware specific settings to initialize I2S_MCK generator */
        if (dev->caps && dev->caps->mck_init) {
                err = dev->caps->mck_init(dev, np);
                if (err)
                        return err;
        }

        /* Enable the peripheral clock. */
        err = clk_prepare_enable(dev->pclk);
        if (err)
                return err;

        /* Get IP version. */
        regmap_read(dev->regmap, ATMEL_I2SC_VERSION, &version);
        dev_info(&pdev->dev, "hw version: %#x\n", version);

        /* Enable error interrupts. */
        regmap_write(dev->regmap, ATMEL_I2SC_IER,
                     ATMEL_I2SC_INT_RXOR | ATMEL_I2SC_INT_TXUR);

        err = devm_snd_soc_register_component(&pdev->dev,
                                              &atmel_i2s_component,
                                              &atmel_i2s_dai, 1);
        if (err) {
                dev_err(&pdev->dev, "failed to register DAI: %d\n", err);
                clk_disable_unprepare(dev->pclk);
                return err;
        }

        /* Prepare DMA config. */
        dev->playback.addr      = (dma_addr_t)mem->start + ATMEL_I2SC_THR;
        dev->playback.maxburst  = 1;
        dev->capture.addr       = (dma_addr_t)mem->start + ATMEL_I2SC_RHR;
        dev->capture.maxburst   = 1;

        if (of_property_match_string(np, "dma-names", "rx-tx") == 0)
                pcm_flags |= SND_DMAENGINE_PCM_FLAG_HALF_DUPLEX;
        err = devm_snd_dmaengine_pcm_register(&pdev->dev, NULL, pcm_flags);
        if (err) {
                dev_err(&pdev->dev, "failed to register PCM: %d\n", err);
                clk_disable_unprepare(dev->pclk);
                return err;
        }

        return 0;
}

static int atmel_i2s_remove(struct platform_device *pdev)
{
        struct atmel_i2s_dev *dev = platform_get_drvdata(pdev);

        clk_disable_unprepare(dev->pclk);

        return 0;
}

static struct platform_driver atmel_i2s_driver = {
        .driver         = {
                .name   = "atmel_i2s",
                .of_match_table = of_match_ptr(atmel_i2s_dt_ids),
        },
        .probe          = atmel_i2s_probe,
        .remove         = atmel_i2s_remove,
};
module_platform_driver(atmel_i2s_driver);

MODULE_DESCRIPTION("Atmel I2S Controller driver");
MODULE_AUTHOR("Cyrille Pitchen <cyrille.pitchen@atmel.com>");
MODULE_LICENSE("GPL v2");