Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc-2.6

[nv-tegra-linux-2.6.git] / sound / soc / davinci / davinci-i2s.c

/*
 * ALSA SoC I2S (McBSP) Audio Layer for TI DAVINCI processor
 *
 * Author:      Vladimir Barinov, <vbarinov@embeddedalley.com>
 * Copyright:   (C) 2007 MontaVista Software, Inc., <source@mvista.com>
 *
 * 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/init.h>
#include <linux/module.h>
#include <linux/device.h>
#include <linux/delay.h>
#include <linux/io.h>
#include <linux/clk.h>

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

#include <mach/asp.h>

#include "davinci-pcm.h"


/*
 * NOTE:  terminology here is confusing.
 *
 *  - This driver supports the "Audio Serial Port" (ASP),
 *    found on dm6446, dm355, and other DaVinci chips.
 *
 *  - But it labels it a "Multi-channel Buffered Serial Port"
 *    (McBSP) as on older chips like the dm642 ... which was
 *    backward-compatible, possibly explaining that confusion.
 *
 *  - OMAP chips have a controller called McBSP, which is
 *    incompatible with the DaVinci flavor of McBSP.
 *
 *  - Newer DaVinci chips have a controller called McASP,
 *    incompatible with ASP and with either McBSP.
 *
 * In short:  this uses ASP to implement I2S, not McBSP.
 * And it won't be the only DaVinci implemention of I2S.
 */
#define DAVINCI_MCBSP_DRR_REG   0x00
#define DAVINCI_MCBSP_DXR_REG   0x04
#define DAVINCI_MCBSP_SPCR_REG  0x08
#define DAVINCI_MCBSP_RCR_REG   0x0c
#define DAVINCI_MCBSP_XCR_REG   0x10
#define DAVINCI_MCBSP_SRGR_REG  0x14
#define DAVINCI_MCBSP_PCR_REG   0x24

#define DAVINCI_MCBSP_SPCR_RRST         (1 << 0)
#define DAVINCI_MCBSP_SPCR_RINTM(v)     ((v) << 4)
#define DAVINCI_MCBSP_SPCR_XRST         (1 << 16)
#define DAVINCI_MCBSP_SPCR_XINTM(v)     ((v) << 20)
#define DAVINCI_MCBSP_SPCR_GRST         (1 << 22)
#define DAVINCI_MCBSP_SPCR_FRST         (1 << 23)
#define DAVINCI_MCBSP_SPCR_FREE         (1 << 25)

#define DAVINCI_MCBSP_RCR_RWDLEN1(v)    ((v) << 5)
#define DAVINCI_MCBSP_RCR_RFRLEN1(v)    ((v) << 8)
#define DAVINCI_MCBSP_RCR_RDATDLY(v)    ((v) << 16)
#define DAVINCI_MCBSP_RCR_RFIG          (1 << 18)
#define DAVINCI_MCBSP_RCR_RWDLEN2(v)    ((v) << 21)

#define DAVINCI_MCBSP_XCR_XWDLEN1(v)    ((v) << 5)
#define DAVINCI_MCBSP_XCR_XFRLEN1(v)    ((v) << 8)
#define DAVINCI_MCBSP_XCR_XDATDLY(v)    ((v) << 16)
#define DAVINCI_MCBSP_XCR_XFIG          (1 << 18)
#define DAVINCI_MCBSP_XCR_XWDLEN2(v)    ((v) << 21)

#define DAVINCI_MCBSP_SRGR_FWID(v)      ((v) << 8)
#define DAVINCI_MCBSP_SRGR_FPER(v)      ((v) << 16)
#define DAVINCI_MCBSP_SRGR_FSGM         (1 << 28)

#define DAVINCI_MCBSP_PCR_CLKRP         (1 << 0)
#define DAVINCI_MCBSP_PCR_CLKXP         (1 << 1)
#define DAVINCI_MCBSP_PCR_FSRP          (1 << 2)
#define DAVINCI_MCBSP_PCR_FSXP          (1 << 3)
#define DAVINCI_MCBSP_PCR_SCLKME        (1 << 7)
#define DAVINCI_MCBSP_PCR_CLKRM         (1 << 8)
#define DAVINCI_MCBSP_PCR_CLKXM         (1 << 9)
#define DAVINCI_MCBSP_PCR_FSRM          (1 << 10)
#define DAVINCI_MCBSP_PCR_FSXM          (1 << 11)

enum {
        DAVINCI_MCBSP_WORD_8 = 0,
        DAVINCI_MCBSP_WORD_12,
        DAVINCI_MCBSP_WORD_16,
        DAVINCI_MCBSP_WORD_20,
        DAVINCI_MCBSP_WORD_24,
        DAVINCI_MCBSP_WORD_32,
};

static const unsigned char data_type[SNDRV_PCM_FORMAT_S32_LE + 1] = {
        [SNDRV_PCM_FORMAT_S8]           = 1,
        [SNDRV_PCM_FORMAT_S16_LE]       = 2,
        [SNDRV_PCM_FORMAT_S32_LE]       = 4,
};

static const unsigned char asp_word_length[SNDRV_PCM_FORMAT_S32_LE + 1] = {
        [SNDRV_PCM_FORMAT_S8]           = DAVINCI_MCBSP_WORD_8,
        [SNDRV_PCM_FORMAT_S16_LE]       = DAVINCI_MCBSP_WORD_16,
        [SNDRV_PCM_FORMAT_S32_LE]       = DAVINCI_MCBSP_WORD_32,
};

static const unsigned char double_fmt[SNDRV_PCM_FORMAT_S32_LE + 1] = {
        [SNDRV_PCM_FORMAT_S8]           = SNDRV_PCM_FORMAT_S16_LE,
        [SNDRV_PCM_FORMAT_S16_LE]       = SNDRV_PCM_FORMAT_S32_LE,
};

struct davinci_mcbsp_dev {
        struct davinci_pcm_dma_params   dma_params[2];
        void __iomem                    *base;
#define MOD_DSP_A       0
#define MOD_DSP_B       1
        int                             mode;
        u32                             pcr;
        struct clk                      *clk;
        /*
         * Combining both channels into 1 element will at least double the
         * amount of time between servicing the dma channel, increase
         * effiency, and reduce the chance of overrun/underrun. But,
         * it will result in the left & right channels being swapped.
         *
         * If relabeling the left and right channels is not possible,
         * you may want to let the codec know to swap them back.
         *
         * It may allow x10 the amount of time to service dma requests,
         * if the codec is master and is using an unnecessarily fast bit clock
         * (ie. tlvaic23b), independent of the sample rate. So, having an
         * entire frame at once means it can be serviced at the sample rate
         * instead of the bit clock rate.
         *
         * In the now unlikely case that an underrun still
         * occurs, both the left and right samples will be repeated
         * so that no pops are heard, and the left and right channels
         * won't end up being swapped because of the underrun.
         */
        unsigned enable_channel_combine:1;
};

static inline void davinci_mcbsp_write_reg(struct davinci_mcbsp_dev *dev,
                                           int reg, u32 val)
{
        __raw_writel(val, dev->base + reg);
}

static inline u32 davinci_mcbsp_read_reg(struct davinci_mcbsp_dev *dev, int reg)
{
        return __raw_readl(dev->base + reg);
}

static void toggle_clock(struct davinci_mcbsp_dev *dev, int playback)
{
        u32 m = playback ? DAVINCI_MCBSP_PCR_CLKXP : DAVINCI_MCBSP_PCR_CLKRP;
        /* The clock needs to toggle to complete reset.
         * So, fake it by toggling the clk polarity.
         */
        davinci_mcbsp_write_reg(dev, DAVINCI_MCBSP_PCR_REG, dev->pcr ^ m);
        davinci_mcbsp_write_reg(dev, DAVINCI_MCBSP_PCR_REG, dev->pcr);
}

static void davinci_mcbsp_start(struct davinci_mcbsp_dev *dev,
                struct snd_pcm_substream *substream)
{
        struct snd_soc_pcm_runtime *rtd = substream->private_data;
        struct snd_soc_device *socdev = rtd->socdev;
        struct snd_soc_platform *platform = socdev->card->platform;
        int playback = (substream->stream == SNDRV_PCM_STREAM_PLAYBACK);
        u32 spcr;
        u32 mask = playback ? DAVINCI_MCBSP_SPCR_XRST : DAVINCI_MCBSP_SPCR_RRST;
        spcr = davinci_mcbsp_read_reg(dev, DAVINCI_MCBSP_SPCR_REG);
        if (spcr & mask) {
                /* start off disabled */
                davinci_mcbsp_write_reg(dev, DAVINCI_MCBSP_SPCR_REG,
                                spcr & ~mask);
                toggle_clock(dev, playback);
        }
        if (dev->pcr & (DAVINCI_MCBSP_PCR_FSXM | DAVINCI_MCBSP_PCR_FSRM |
                        DAVINCI_MCBSP_PCR_CLKXM | DAVINCI_MCBSP_PCR_CLKRM)) {
                /* Start the sample generator */
                spcr |= DAVINCI_MCBSP_SPCR_GRST;
                davinci_mcbsp_write_reg(dev, DAVINCI_MCBSP_SPCR_REG, spcr);
        }

        if (playback) {
                /* Stop the DMA to avoid data loss */
                /* while the transmitter is out of reset to handle XSYNCERR */
                if (platform->pcm_ops->trigger) {
                        int ret = platform->pcm_ops->trigger(substream,
                                SNDRV_PCM_TRIGGER_STOP);
                        if (ret < 0)
                                printk(KERN_DEBUG "Playback DMA stop failed\n");
                }

                /* Enable the transmitter */
                spcr = davinci_mcbsp_read_reg(dev, DAVINCI_MCBSP_SPCR_REG);
                spcr |= DAVINCI_MCBSP_SPCR_XRST;
                davinci_mcbsp_write_reg(dev, DAVINCI_MCBSP_SPCR_REG, spcr);

                /* wait for any unexpected frame sync error to occur */
                udelay(100);

                /* Disable the transmitter to clear any outstanding XSYNCERR */
                spcr = davinci_mcbsp_read_reg(dev, DAVINCI_MCBSP_SPCR_REG);
                spcr &= ~DAVINCI_MCBSP_SPCR_XRST;
                davinci_mcbsp_write_reg(dev, DAVINCI_MCBSP_SPCR_REG, spcr);
                toggle_clock(dev, playback);

                /* Restart the DMA */
                if (platform->pcm_ops->trigger) {
                        int ret = platform->pcm_ops->trigger(substream,
                                SNDRV_PCM_TRIGGER_START);
                        if (ret < 0)
                                printk(KERN_DEBUG "Playback DMA start failed\n");
                }
        }

        /* Enable transmitter or receiver */
        spcr = davinci_mcbsp_read_reg(dev, DAVINCI_MCBSP_SPCR_REG);
        spcr |= mask;

        if (dev->pcr & (DAVINCI_MCBSP_PCR_FSXM | DAVINCI_MCBSP_PCR_FSRM)) {
                /* Start frame sync */
                spcr |= DAVINCI_MCBSP_SPCR_FRST;
        }
        davinci_mcbsp_write_reg(dev, DAVINCI_MCBSP_SPCR_REG, spcr);
}

static void davinci_mcbsp_stop(struct davinci_mcbsp_dev *dev, int playback)
{
        u32 spcr;

        /* Reset transmitter/receiver and sample rate/frame sync generators */
        spcr = davinci_mcbsp_read_reg(dev, DAVINCI_MCBSP_SPCR_REG);
        spcr &= ~(DAVINCI_MCBSP_SPCR_GRST | DAVINCI_MCBSP_SPCR_FRST);
        spcr &= playback ? ~DAVINCI_MCBSP_SPCR_XRST : ~DAVINCI_MCBSP_SPCR_RRST;
        davinci_mcbsp_write_reg(dev, DAVINCI_MCBSP_SPCR_REG, spcr);
        toggle_clock(dev, playback);
}

#define DEFAULT_BITPERSAMPLE    16

static int davinci_i2s_set_dai_fmt(struct snd_soc_dai *cpu_dai,
                                   unsigned int fmt)
{
        struct davinci_mcbsp_dev *dev = cpu_dai->private_data;
        unsigned int pcr;
        unsigned int srgr;
        srgr = DAVINCI_MCBSP_SRGR_FSGM |
                DAVINCI_MCBSP_SRGR_FPER(DEFAULT_BITPERSAMPLE * 2 - 1) |
                DAVINCI_MCBSP_SRGR_FWID(DEFAULT_BITPERSAMPLE - 1);

        /* set master/slave audio interface */
        switch (fmt & SND_SOC_DAIFMT_MASTER_MASK) {
        case SND_SOC_DAIFMT_CBS_CFS:
                /* cpu is master */
                pcr = DAVINCI_MCBSP_PCR_FSXM |
                        DAVINCI_MCBSP_PCR_FSRM |
                        DAVINCI_MCBSP_PCR_CLKXM |
                        DAVINCI_MCBSP_PCR_CLKRM;
                break;
        case SND_SOC_DAIFMT_CBM_CFS:
                /* McBSP CLKR pin is the input for the Sample Rate Generator.
                 * McBSP FSR and FSX are driven by the Sample Rate Generator. */
                pcr = DAVINCI_MCBSP_PCR_SCLKME |
                        DAVINCI_MCBSP_PCR_FSXM |
                        DAVINCI_MCBSP_PCR_FSRM;
                break;
        case SND_SOC_DAIFMT_CBM_CFM:
                /* codec is master */
                pcr = 0;
                break;
        default:
                printk(KERN_ERR "%s:bad master\n", __func__);
                return -EINVAL;
        }

        /* interface format */
        switch (fmt & SND_SOC_DAIFMT_FORMAT_MASK) {
        case SND_SOC_DAIFMT_I2S:
                /* Davinci doesn't support TRUE I2S, but some codecs will have
                 * the left and right channels contiguous. This allows
                 * dsp_a mode to be used with an inverted normal frame clk.
                 * If your codec is master and does not have contiguous
                 * channels, then you will have sound on only one channel.
                 * Try using a different mode, or codec as slave.
                 *
                 * The TLV320AIC33 is an example of a codec where this works.
                 * It has a variable bit clock frequency allowing it to have
                 * valid data on every bit clock.
                 *
                 * The TLV320AIC23 is an example of a codec where this does not
                 * work. It has a fixed bit clock frequency with progressively
                 * more empty bit clock slots between channels as the sample
                 * rate is lowered.
                 */
                fmt ^= SND_SOC_DAIFMT_NB_IF;
        case SND_SOC_DAIFMT_DSP_A:
                dev->mode = MOD_DSP_A;
                break;
        case SND_SOC_DAIFMT_DSP_B:
                dev->mode = MOD_DSP_B;
                break;
        default:
                printk(KERN_ERR "%s:bad format\n", __func__);
                return -EINVAL;
        }

        switch (fmt & SND_SOC_DAIFMT_INV_MASK) {
        case SND_SOC_DAIFMT_NB_NF:
                /* CLKRP Receive clock polarity,
                 *      1 - sampled on rising edge of CLKR
                 *      valid on rising edge
                 * CLKXP Transmit clock polarity,
                 *      1 - clocked on falling edge of CLKX
                 *      valid on rising edge
                 * FSRP  Receive frame sync pol, 0 - active high
                 * FSXP  Transmit frame sync pol, 0 - active high
                 */
                pcr |= (DAVINCI_MCBSP_PCR_CLKXP | DAVINCI_MCBSP_PCR_CLKRP);
                break;
        case SND_SOC_DAIFMT_IB_IF:
                /* CLKRP Receive clock polarity,
                 *      0 - sampled on falling edge of CLKR
                 *      valid on falling edge
                 * CLKXP Transmit clock polarity,
                 *      0 - clocked on rising edge of CLKX
                 *      valid on falling edge
                 * FSRP  Receive frame sync pol, 1 - active low
                 * FSXP  Transmit frame sync pol, 1 - active low
                 */
                pcr |= (DAVINCI_MCBSP_PCR_FSXP | DAVINCI_MCBSP_PCR_FSRP);
                break;
        case SND_SOC_DAIFMT_NB_IF:
                /* CLKRP Receive clock polarity,
                 *      1 - sampled on rising edge of CLKR
                 *      valid on rising edge
                 * CLKXP Transmit clock polarity,
                 *      1 - clocked on falling edge of CLKX
                 *      valid on rising edge
                 * FSRP  Receive frame sync pol, 1 - active low
                 * FSXP  Transmit frame sync pol, 1 - active low
                 */
                pcr |= (DAVINCI_MCBSP_PCR_CLKXP | DAVINCI_MCBSP_PCR_CLKRP |
                        DAVINCI_MCBSP_PCR_FSXP | DAVINCI_MCBSP_PCR_FSRP);
                break;
        case SND_SOC_DAIFMT_IB_NF:
                /* CLKRP Receive clock polarity,
                 *      0 - sampled on falling edge of CLKR
                 *      valid on falling edge
                 * CLKXP Transmit clock polarity,
                 *      0 - clocked on rising edge of CLKX
                 *      valid on falling edge
                 * FSRP  Receive frame sync pol, 0 - active high
                 * FSXP  Transmit frame sync pol, 0 - active high
                 */
                break;
        default:
                return -EINVAL;
        }
        davinci_mcbsp_write_reg(dev, DAVINCI_MCBSP_SRGR_REG, srgr);
        dev->pcr = pcr;
        davinci_mcbsp_write_reg(dev, DAVINCI_MCBSP_PCR_REG, pcr);
        return 0;
}

static int davinci_i2s_hw_params(struct snd_pcm_substream *substream,
                                 struct snd_pcm_hw_params *params,
                                 struct snd_soc_dai *dai)
{
        struct davinci_mcbsp_dev *dev = dai->private_data;
        struct davinci_pcm_dma_params *dma_params =
                                        &dev->dma_params[substream->stream];
        struct snd_interval *i = NULL;
        int mcbsp_word_length;
        unsigned int rcr, xcr, srgr;
        u32 spcr;
        snd_pcm_format_t fmt;
        unsigned element_cnt = 1;

        /* general line settings */
        spcr = davinci_mcbsp_read_reg(dev, DAVINCI_MCBSP_SPCR_REG);
        if (substream->stream == SNDRV_PCM_STREAM_CAPTURE) {
                spcr |= DAVINCI_MCBSP_SPCR_RINTM(3) | DAVINCI_MCBSP_SPCR_FREE;
                davinci_mcbsp_write_reg(dev, DAVINCI_MCBSP_SPCR_REG, spcr);
        } else {
                spcr |= DAVINCI_MCBSP_SPCR_XINTM(3) | DAVINCI_MCBSP_SPCR_FREE;
                davinci_mcbsp_write_reg(dev, DAVINCI_MCBSP_SPCR_REG, spcr);
        }

        i = hw_param_interval(params, SNDRV_PCM_HW_PARAM_SAMPLE_BITS);
        srgr = DAVINCI_MCBSP_SRGR_FSGM;
        srgr |= DAVINCI_MCBSP_SRGR_FWID(snd_interval_value(i) - 1);

        i = hw_param_interval(params, SNDRV_PCM_HW_PARAM_FRAME_BITS);
        srgr |= DAVINCI_MCBSP_SRGR_FPER(snd_interval_value(i) - 1);
        davinci_mcbsp_write_reg(dev, DAVINCI_MCBSP_SRGR_REG, srgr);

        rcr = DAVINCI_MCBSP_RCR_RFIG;
        xcr = DAVINCI_MCBSP_XCR_XFIG;
        if (dev->mode == MOD_DSP_B) {
                rcr |= DAVINCI_MCBSP_RCR_RDATDLY(0);
                xcr |= DAVINCI_MCBSP_XCR_XDATDLY(0);
        } else {
                rcr |= DAVINCI_MCBSP_RCR_RDATDLY(1);
                xcr |= DAVINCI_MCBSP_XCR_XDATDLY(1);
        }
        /* Determine xfer data type */
        fmt = params_format(params);
        if ((fmt > SNDRV_PCM_FORMAT_S32_LE) || !data_type[fmt]) {
                printk(KERN_WARNING "davinci-i2s: unsupported PCM format\n");
                return -EINVAL;
        }

        if (params_channels(params) == 2) {
                element_cnt = 2;
                if (double_fmt[fmt] && dev->enable_channel_combine) {
                        element_cnt = 1;
                        fmt = double_fmt[fmt];
                }
        }
        dma_params->acnt = dma_params->data_type = data_type[fmt];
        dma_params->fifo_level = 0;
        mcbsp_word_length = asp_word_length[fmt];
        rcr |= DAVINCI_MCBSP_RCR_RFRLEN1(element_cnt - 1);
        xcr |= DAVINCI_MCBSP_XCR_XFRLEN1(element_cnt - 1);

        rcr |= DAVINCI_MCBSP_RCR_RWDLEN1(mcbsp_word_length) |
                DAVINCI_MCBSP_RCR_RWDLEN2(mcbsp_word_length);
        xcr |= DAVINCI_MCBSP_XCR_XWDLEN1(mcbsp_word_length) |
                DAVINCI_MCBSP_XCR_XWDLEN2(mcbsp_word_length);

        if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
                davinci_mcbsp_write_reg(dev, DAVINCI_MCBSP_XCR_REG, xcr);
        else
                davinci_mcbsp_write_reg(dev, DAVINCI_MCBSP_RCR_REG, rcr);
        return 0;
}

static int davinci_i2s_prepare(struct snd_pcm_substream *substream,
                struct snd_soc_dai *dai)
{
        struct davinci_mcbsp_dev *dev = dai->private_data;
        int playback = (substream->stream == SNDRV_PCM_STREAM_PLAYBACK);
        davinci_mcbsp_stop(dev, playback);
        if ((dev->pcr & DAVINCI_MCBSP_PCR_FSXM) == 0) {
                /* codec is master */
                davinci_mcbsp_start(dev, substream);
        }
        return 0;
}

static int davinci_i2s_trigger(struct snd_pcm_substream *substream, int cmd,
                               struct snd_soc_dai *dai)
{
        struct davinci_mcbsp_dev *dev = dai->private_data;
        int ret = 0;
        int playback = (substream->stream == SNDRV_PCM_STREAM_PLAYBACK);
        if ((dev->pcr & DAVINCI_MCBSP_PCR_FSXM) == 0)
                return 0;       /* return if codec is master */

        switch (cmd) {
        case SNDRV_PCM_TRIGGER_START:
        case SNDRV_PCM_TRIGGER_RESUME:
        case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:
                davinci_mcbsp_start(dev, substream);
                break;
        case SNDRV_PCM_TRIGGER_STOP:
        case SNDRV_PCM_TRIGGER_SUSPEND:
        case SNDRV_PCM_TRIGGER_PAUSE_PUSH:
                davinci_mcbsp_stop(dev, playback);
                break;
        default:
                ret = -EINVAL;
        }
        return ret;
}

static void davinci_i2s_shutdown(struct snd_pcm_substream *substream,
                struct snd_soc_dai *dai)
{
        struct davinci_mcbsp_dev *dev = dai->private_data;
        int playback = (substream->stream == SNDRV_PCM_STREAM_PLAYBACK);
        davinci_mcbsp_stop(dev, playback);
}

#define DAVINCI_I2S_RATES       SNDRV_PCM_RATE_8000_96000

static struct snd_soc_dai_ops davinci_i2s_dai_ops = {
        .shutdown       = davinci_i2s_shutdown,
        .prepare        = davinci_i2s_prepare,
        .trigger        = davinci_i2s_trigger,
        .hw_params      = davinci_i2s_hw_params,
        .set_fmt        = davinci_i2s_set_dai_fmt,

};

struct snd_soc_dai davinci_i2s_dai = {
        .name = "davinci-i2s",
        .id = 0,
        .playback = {
                .channels_min = 2,
                .channels_max = 2,
                .rates = DAVINCI_I2S_RATES,
                .formats = SNDRV_PCM_FMTBIT_S16_LE,},
        .capture = {
                .channels_min = 2,
                .channels_max = 2,
                .rates = DAVINCI_I2S_RATES,
                .formats = SNDRV_PCM_FMTBIT_S16_LE,},
        .ops = &davinci_i2s_dai_ops,

};
EXPORT_SYMBOL_GPL(davinci_i2s_dai);

static int davinci_i2s_probe(struct platform_device *pdev)
{
        struct snd_platform_data *pdata = pdev->dev.platform_data;
        struct davinci_mcbsp_dev *dev;
        struct resource *mem, *ioarea, *res;
        int ret;

        mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        if (!mem) {
                dev_err(&pdev->dev, "no mem resource?\n");
                return -ENODEV;
        }

        ioarea = request_mem_region(mem->start, (mem->end - mem->start) + 1,
                                    pdev->name);
        if (!ioarea) {
                dev_err(&pdev->dev, "McBSP region already claimed\n");
                return -EBUSY;
        }

        dev = kzalloc(sizeof(struct davinci_mcbsp_dev), GFP_KERNEL);
        if (!dev) {
                ret = -ENOMEM;
                goto err_release_region;
        }
        if (pdata) {
                dev->enable_channel_combine = pdata->enable_channel_combine;
                dev->dma_params[SNDRV_PCM_STREAM_PLAYBACK].sram_size =
                        pdata->sram_size_playback;
                dev->dma_params[SNDRV_PCM_STREAM_CAPTURE].sram_size =
                        pdata->sram_size_capture;
        }
        dev->clk = clk_get(&pdev->dev, NULL);
        if (IS_ERR(dev->clk)) {
                ret = -ENODEV;
                goto err_free_mem;
        }
        clk_enable(dev->clk);

        dev->base = (void __iomem *)IO_ADDRESS(mem->start);

        dev->dma_params[SNDRV_PCM_STREAM_PLAYBACK].dma_addr =
            (dma_addr_t)(io_v2p(dev->base) + DAVINCI_MCBSP_DXR_REG);

        dev->dma_params[SNDRV_PCM_STREAM_CAPTURE].dma_addr =
            (dma_addr_t)(io_v2p(dev->base) + DAVINCI_MCBSP_DRR_REG);

        /* first TX, then RX */
        res = platform_get_resource(pdev, IORESOURCE_DMA, 0);
        if (!res) {
                dev_err(&pdev->dev, "no DMA resource\n");
                ret = -ENXIO;
                goto err_free_mem;
        }
        dev->dma_params[SNDRV_PCM_STREAM_PLAYBACK].channel = res->start;

        res = platform_get_resource(pdev, IORESOURCE_DMA, 1);
        if (!res) {
                dev_err(&pdev->dev, "no DMA resource\n");
                ret = -ENXIO;
                goto err_free_mem;
        }
        dev->dma_params[SNDRV_PCM_STREAM_CAPTURE].channel = res->start;

        davinci_i2s_dai.private_data = dev;
        davinci_i2s_dai.dma_data = dev->dma_params;
        ret = snd_soc_register_dai(&davinci_i2s_dai);
        if (ret != 0)
                goto err_free_mem;

        return 0;

err_free_mem:
        kfree(dev);
err_release_region:
        release_mem_region(mem->start, (mem->end - mem->start) + 1);

        return ret;
}

static int davinci_i2s_remove(struct platform_device *pdev)
{
        struct davinci_mcbsp_dev *dev = davinci_i2s_dai.private_data;
        struct resource *mem;

        snd_soc_unregister_dai(&davinci_i2s_dai);
        clk_disable(dev->clk);
        clk_put(dev->clk);
        dev->clk = NULL;
        kfree(dev);
        mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        release_mem_region(mem->start, (mem->end - mem->start) + 1);

        return 0;
}

static struct platform_driver davinci_mcbsp_driver = {
        .probe          = davinci_i2s_probe,
        .remove         = davinci_i2s_remove,
        .driver         = {
                .name   = "davinci-asp",
                .owner  = THIS_MODULE,
        },
};

static int __init davinci_i2s_init(void)
{
        return platform_driver_register(&davinci_mcbsp_driver);
}
module_init(davinci_i2s_init);

static void __exit davinci_i2s_exit(void)
{
        platform_driver_unregister(&davinci_mcbsp_driver);
}
module_exit(davinci_i2s_exit);

MODULE_AUTHOR("Vladimir Barinov");
MODULE_DESCRIPTION("TI DAVINCI I2S (McBSP) SoC Interface");
MODULE_LICENSE("GPL");