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[pohmelfs.git] / sound / i2c / cs8427.c

/*
 *  Routines for control of the CS8427 via i2c bus
 *  IEC958 (S/PDIF) receiver & transmitter by Cirrus Logic
 *  Copyright (c) by Jaroslav Kysela <perex@perex.cz>
 *
 *
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation; either version 2 of the License, or
 *   (at your option) any later version.
 *
 *   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.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program; if not, write to the Free Software
 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
 *
 */

#include <linux/slab.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/bitrev.h>
#include <linux/module.h>
#include <asm/unaligned.h>
#include <sound/core.h>
#include <sound/control.h>
#include <sound/pcm.h>
#include <sound/cs8427.h>
#include <sound/asoundef.h>

static void snd_cs8427_reset(struct snd_i2c_device *cs8427);

MODULE_AUTHOR("Jaroslav Kysela <perex@perex.cz>");
MODULE_DESCRIPTION("IEC958 (S/PDIF) receiver & transmitter by Cirrus Logic");
MODULE_LICENSE("GPL");

#define CS8427_ADDR                     (0x20>>1) /* fixed address */

struct cs8427_stream {
        struct snd_pcm_substream *substream;
        char hw_status[24];             /* hardware status */
        char def_status[24];            /* default status */
        char pcm_status[24];            /* PCM private status */
        char hw_udata[32];
        struct snd_kcontrol *pcm_ctl;
};

struct cs8427 {
        unsigned char regmap[0x14];     /* map of first 1 + 13 registers */
        unsigned int rate;
        unsigned int reset_timeout;
        struct cs8427_stream playback;
        struct cs8427_stream capture;
};

int snd_cs8427_reg_write(struct snd_i2c_device *device, unsigned char reg,
                         unsigned char val)
{
        int err;
        unsigned char buf[2];

        buf[0] = reg & 0x7f;
        buf[1] = val;
        if ((err = snd_i2c_sendbytes(device, buf, 2)) != 2) {
                snd_printk(KERN_ERR "unable to send bytes 0x%02x:0x%02x "
                           "to CS8427 (%i)\n", buf[0], buf[1], err);
                return err < 0 ? err : -EIO;
        }
        return 0;
}

EXPORT_SYMBOL(snd_cs8427_reg_write);

static int snd_cs8427_reg_read(struct snd_i2c_device *device, unsigned char reg)
{
        int err;
        unsigned char buf;

        if ((err = snd_i2c_sendbytes(device, &reg, 1)) != 1) {
                snd_printk(KERN_ERR "unable to send register 0x%x byte "
                           "to CS8427\n", reg);
                return err < 0 ? err : -EIO;
        }
        if ((err = snd_i2c_readbytes(device, &buf, 1)) != 1) {
                snd_printk(KERN_ERR "unable to read register 0x%x byte "
                           "from CS8427\n", reg);
                return err < 0 ? err : -EIO;
        }
        return buf;
}

static int snd_cs8427_select_corudata(struct snd_i2c_device *device, int udata)
{
        struct cs8427 *chip = device->private_data;
        int err;

        udata = udata ? CS8427_BSEL : 0;
        if (udata != (chip->regmap[CS8427_REG_CSDATABUF] & udata)) {
                chip->regmap[CS8427_REG_CSDATABUF] &= ~CS8427_BSEL;
                chip->regmap[CS8427_REG_CSDATABUF] |= udata;
                err = snd_cs8427_reg_write(device, CS8427_REG_CSDATABUF,
                                           chip->regmap[CS8427_REG_CSDATABUF]);
                if (err < 0)
                        return err;
        }
        return 0;
}

static int snd_cs8427_send_corudata(struct snd_i2c_device *device,
                                    int udata,
                                    unsigned char *ndata,
                                    int count)
{
        struct cs8427 *chip = device->private_data;
        char *hw_data = udata ?
                chip->playback.hw_udata : chip->playback.hw_status;
        char data[32];
        int err, idx;

        if (!memcmp(hw_data, ndata, count))
                return 0;
        if ((err = snd_cs8427_select_corudata(device, udata)) < 0)
                return err;
        memcpy(hw_data, ndata, count);
        if (udata) {
                memset(data, 0, sizeof(data));
                if (memcmp(hw_data, data, count) == 0) {
                        chip->regmap[CS8427_REG_UDATABUF] &= ~CS8427_UBMMASK;
                        chip->regmap[CS8427_REG_UDATABUF] |= CS8427_UBMZEROS |
                                CS8427_EFTUI;
                        err = snd_cs8427_reg_write(device, CS8427_REG_UDATABUF,
                                                   chip->regmap[CS8427_REG_UDATABUF]);
                        return err < 0 ? err : 0;
                }
        }
        data[0] = CS8427_REG_AUTOINC | CS8427_REG_CORU_DATABUF;
        for (idx = 0; idx < count; idx++)
                data[idx + 1] = bitrev8(ndata[idx]);
        if (snd_i2c_sendbytes(device, data, count + 1) != count + 1)
                return -EIO;
        return 1;
}

static void snd_cs8427_free(struct snd_i2c_device *device)
{
        kfree(device->private_data);
}

int snd_cs8427_create(struct snd_i2c_bus *bus,
                      unsigned char addr,
                      unsigned int reset_timeout,
                      struct snd_i2c_device **r_cs8427)
{
        static unsigned char initvals1[] = {
          CS8427_REG_CONTROL1 | CS8427_REG_AUTOINC,
          /* CS8427_REG_CONTROL1: RMCK to OMCK, valid PCM audio, disable mutes,
             TCBL=output */
          CS8427_SWCLK | CS8427_TCBLDIR,
          /* CS8427_REG_CONTROL2: hold last valid audio sample, RMCK=256*Fs,
             normal stereo operation */
          0x00,
          /* CS8427_REG_DATAFLOW: output drivers normal operation, Tx<=serial,
             Rx=>serial */
          CS8427_TXDSERIAL | CS8427_SPDAES3RECEIVER,
          /* CS8427_REG_CLOCKSOURCE: Run off, CMCK=256*Fs,
             output time base = OMCK, input time base = recovered input clock,
             recovered input clock source is ILRCK changed to AES3INPUT
             (workaround, see snd_cs8427_reset) */
          CS8427_RXDILRCK,
          /* CS8427_REG_SERIALINPUT: Serial audio input port data format = I2S,
             24-bit, 64*Fsi */
          CS8427_SIDEL | CS8427_SILRPOL,
          /* CS8427_REG_SERIALOUTPUT: Serial audio output port data format
             = I2S, 24-bit, 64*Fsi */
          CS8427_SODEL | CS8427_SOLRPOL,
        };
        static unsigned char initvals2[] = {
          CS8427_REG_RECVERRMASK | CS8427_REG_AUTOINC,
          /* CS8427_REG_RECVERRMASK: unmask the input PLL clock, V, confidence,
             biphase, parity status bits */
          /* CS8427_UNLOCK | CS8427_V | CS8427_CONF | CS8427_BIP | CS8427_PAR,*/
          0xff, /* set everything */
          /* CS8427_REG_CSDATABUF:
             Registers 32-55 window to CS buffer
             Inhibit D->E transfers from overwriting first 5 bytes of CS data.
             Inhibit D->E transfers (all) of CS data.
             Allow E->F transfer of CS data.
             One byte mode; both A/B channels get same written CB data.
             A channel info is output to chip's EMPH* pin. */
          CS8427_CBMR | CS8427_DETCI,
          /* CS8427_REG_UDATABUF:
             Use internal buffer to transmit User (U) data.
             Chip's U pin is an output.
             Transmit all O's for user data.
             Inhibit D->E transfers.
             Inhibit E->F transfers. */
          CS8427_UD | CS8427_EFTUI | CS8427_DETUI,
        };
        int err;
        struct cs8427 *chip;
        struct snd_i2c_device *device;
        unsigned char buf[24];

        if ((err = snd_i2c_device_create(bus, "CS8427",
                                         CS8427_ADDR | (addr & 7),
                                         &device)) < 0)
                return err;
        chip = device->private_data = kzalloc(sizeof(*chip), GFP_KERNEL);
        if (chip == NULL) {
                snd_i2c_device_free(device);
                return -ENOMEM;
        }
        device->private_free = snd_cs8427_free;
        
        snd_i2c_lock(bus);
        err = snd_cs8427_reg_read(device, CS8427_REG_ID_AND_VER);
        if (err != CS8427_VER8427A) {
                /* give second chance */
                snd_printk(KERN_WARNING "invalid CS8427 signature 0x%x: "
                           "let me try again...\n", err);
                err = snd_cs8427_reg_read(device, CS8427_REG_ID_AND_VER);
        }
        if (err != CS8427_VER8427A) {
                snd_i2c_unlock(bus);
                snd_printk(KERN_ERR "unable to find CS8427 signature "
                           "(expected 0x%x, read 0x%x),\n",
                           CS8427_VER8427A, err);
                snd_printk(KERN_ERR "   initialization is not completed\n");
                return -EFAULT;
        }
        /* turn off run bit while making changes to configuration */
        err = snd_cs8427_reg_write(device, CS8427_REG_CLOCKSOURCE, 0x00);
        if (err < 0)
                goto __fail;
        /* send initial values */
        memcpy(chip->regmap + (initvals1[0] & 0x7f), initvals1 + 1, 6);
        if ((err = snd_i2c_sendbytes(device, initvals1, 7)) != 7) {
                err = err < 0 ? err : -EIO;
                goto __fail;
        }
        /* Turn off CS8427 interrupt stuff that is not used in hardware */
        memset(buf, 0, 7);
        /* from address 9 to 15 */
        buf[0] = 9;     /* register */
        if ((err = snd_i2c_sendbytes(device, buf, 7)) != 7)
                goto __fail;
        /* send transfer initialization sequence */
        memcpy(chip->regmap + (initvals2[0] & 0x7f), initvals2 + 1, 3);
        if ((err = snd_i2c_sendbytes(device, initvals2, 4)) != 4) {
                err = err < 0 ? err : -EIO;
                goto __fail;
        }
        /* write default channel status bytes */
        put_unaligned_le32(SNDRV_PCM_DEFAULT_CON_SPDIF, buf);
        memset(buf + 4, 0, 24 - 4);
        if (snd_cs8427_send_corudata(device, 0, buf, 24) < 0)
                goto __fail;
        memcpy(chip->playback.def_status, buf, 24);
        memcpy(chip->playback.pcm_status, buf, 24);
        snd_i2c_unlock(bus);

        /* turn on run bit and rock'n'roll */
        if (reset_timeout < 1)
                reset_timeout = 1;
        chip->reset_timeout = reset_timeout;
        snd_cs8427_reset(device);

#if 0   // it's nice for read tests
        {
        char buf[128];
        int xx;
        buf[0] = 0x81;
        snd_i2c_sendbytes(device, buf, 1);
        snd_i2c_readbytes(device, buf, 127);
        for (xx = 0; xx < 127; xx++)
                printk(KERN_DEBUG "reg[0x%x] = 0x%x\n", xx+1, buf[xx]);
        }
#endif
        
        if (r_cs8427)
                *r_cs8427 = device;
        return 0;

      __fail:
        snd_i2c_unlock(bus);
        snd_i2c_device_free(device);
        return err < 0 ? err : -EIO;
}

EXPORT_SYMBOL(snd_cs8427_create);

/*
 * Reset the chip using run bit, also lock PLL using ILRCK and
 * put back AES3INPUT. This workaround is described in latest
 * CS8427 datasheet, otherwise TXDSERIAL will not work.
 */
static void snd_cs8427_reset(struct snd_i2c_device *cs8427)
{
        struct cs8427 *chip;
        unsigned long end_time;
        int data, aes3input = 0;

        if (snd_BUG_ON(!cs8427))
                return;
        chip = cs8427->private_data;
        snd_i2c_lock(cs8427->bus);
        if ((chip->regmap[CS8427_REG_CLOCKSOURCE] & CS8427_RXDAES3INPUT) ==
            CS8427_RXDAES3INPUT)  /* AES3 bit is set */
                aes3input = 1;
        chip->regmap[CS8427_REG_CLOCKSOURCE] &= ~(CS8427_RUN | CS8427_RXDMASK);
        snd_cs8427_reg_write(cs8427, CS8427_REG_CLOCKSOURCE,
                             chip->regmap[CS8427_REG_CLOCKSOURCE]);
        udelay(200);
        chip->regmap[CS8427_REG_CLOCKSOURCE] |= CS8427_RUN | CS8427_RXDILRCK;
        snd_cs8427_reg_write(cs8427, CS8427_REG_CLOCKSOURCE,
                             chip->regmap[CS8427_REG_CLOCKSOURCE]);
        udelay(200);
        snd_i2c_unlock(cs8427->bus);
        end_time = jiffies + chip->reset_timeout;
        while (time_after_eq(end_time, jiffies)) {
                snd_i2c_lock(cs8427->bus);
                data = snd_cs8427_reg_read(cs8427, CS8427_REG_RECVERRORS);
                snd_i2c_unlock(cs8427->bus);
                if (!(data & CS8427_UNLOCK))
                        break;
                schedule_timeout_uninterruptible(1);
        }
        snd_i2c_lock(cs8427->bus);
        chip->regmap[CS8427_REG_CLOCKSOURCE] &= ~CS8427_RXDMASK;
        if (aes3input)
                chip->regmap[CS8427_REG_CLOCKSOURCE] |= CS8427_RXDAES3INPUT;
        snd_cs8427_reg_write(cs8427, CS8427_REG_CLOCKSOURCE,
                             chip->regmap[CS8427_REG_CLOCKSOURCE]);
        snd_i2c_unlock(cs8427->bus);
}

static int snd_cs8427_in_status_info(struct snd_kcontrol *kcontrol,
                                     struct snd_ctl_elem_info *uinfo)
{
        uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER;
        uinfo->count = 1;
        uinfo->value.integer.min = 0;
        uinfo->value.integer.max = 255;
        return 0;
}

static int snd_cs8427_in_status_get(struct snd_kcontrol *kcontrol,
                                    struct snd_ctl_elem_value *ucontrol)
{
        struct snd_i2c_device *device = snd_kcontrol_chip(kcontrol);
        int data;

        snd_i2c_lock(device->bus);
        data = snd_cs8427_reg_read(device, kcontrol->private_value);
        snd_i2c_unlock(device->bus);
        if (data < 0)
                return data;
        ucontrol->value.integer.value[0] = data;
        return 0;
}

static int snd_cs8427_qsubcode_info(struct snd_kcontrol *kcontrol,
                                    struct snd_ctl_elem_info *uinfo)
{
        uinfo->type = SNDRV_CTL_ELEM_TYPE_BYTES;
        uinfo->count = 10;
        return 0;
}

static int snd_cs8427_qsubcode_get(struct snd_kcontrol *kcontrol,
                                   struct snd_ctl_elem_value *ucontrol)
{
        struct snd_i2c_device *device = snd_kcontrol_chip(kcontrol);
        unsigned char reg = CS8427_REG_QSUBCODE;
        int err;

        snd_i2c_lock(device->bus);
        if ((err = snd_i2c_sendbytes(device, &reg, 1)) != 1) {
                snd_printk(KERN_ERR "unable to send register 0x%x byte "
                           "to CS8427\n", reg);
                snd_i2c_unlock(device->bus);
                return err < 0 ? err : -EIO;
        }
        err = snd_i2c_readbytes(device, ucontrol->value.bytes.data, 10);
        if (err != 10) {
                snd_printk(KERN_ERR "unable to read Q-subcode bytes "
                           "from CS8427\n");
                snd_i2c_unlock(device->bus);
                return err < 0 ? err : -EIO;
        }
        snd_i2c_unlock(device->bus);
        return 0;
}

static int snd_cs8427_spdif_info(struct snd_kcontrol *kcontrol,
                                 struct snd_ctl_elem_info *uinfo)
{
        uinfo->type = SNDRV_CTL_ELEM_TYPE_IEC958;
        uinfo->count = 1;
        return 0;
}

static int snd_cs8427_spdif_get(struct snd_kcontrol *kcontrol,
                                struct snd_ctl_elem_value *ucontrol)
{
        struct snd_i2c_device *device = snd_kcontrol_chip(kcontrol);
        struct cs8427 *chip = device->private_data;
        
        snd_i2c_lock(device->bus);
        memcpy(ucontrol->value.iec958.status, chip->playback.def_status, 24);
        snd_i2c_unlock(device->bus);
        return 0;
}

static int snd_cs8427_spdif_put(struct snd_kcontrol *kcontrol,
                                struct snd_ctl_elem_value *ucontrol)
{
        struct snd_i2c_device *device = snd_kcontrol_chip(kcontrol);
        struct cs8427 *chip = device->private_data;
        unsigned char *status = kcontrol->private_value ?
                chip->playback.pcm_status : chip->playback.def_status;
        struct snd_pcm_runtime *runtime = chip->playback.substream ?
                chip->playback.substream->runtime : NULL;
        int err, change;

        snd_i2c_lock(device->bus);
        change = memcmp(ucontrol->value.iec958.status, status, 24) != 0;
        memcpy(status, ucontrol->value.iec958.status, 24);
        if (change && (kcontrol->private_value ?
                       runtime != NULL : runtime == NULL)) {
                err = snd_cs8427_send_corudata(device, 0, status, 24);
                if (err < 0)
                        change = err;
        }
        snd_i2c_unlock(device->bus);
        return change;
}

static int snd_cs8427_spdif_mask_info(struct snd_kcontrol *kcontrol,
                                      struct snd_ctl_elem_info *uinfo)
{
        uinfo->type = SNDRV_CTL_ELEM_TYPE_IEC958;
        uinfo->count = 1;
        return 0;
}

static int snd_cs8427_spdif_mask_get(struct snd_kcontrol *kcontrol,
                                      struct snd_ctl_elem_value *ucontrol)
{
        memset(ucontrol->value.iec958.status, 0xff, 24);
        return 0;
}

static struct snd_kcontrol_new snd_cs8427_iec958_controls[] = {
{
        .iface =        SNDRV_CTL_ELEM_IFACE_PCM,
        .info =         snd_cs8427_in_status_info,
        .name =         "IEC958 CS8427 Input Status",
        .access =       (SNDRV_CTL_ELEM_ACCESS_READ |
                         SNDRV_CTL_ELEM_ACCESS_VOLATILE),
        .get =          snd_cs8427_in_status_get,
        .private_value = 15,
},
{
        .iface =        SNDRV_CTL_ELEM_IFACE_PCM,
        .info =         snd_cs8427_in_status_info,
        .name =         "IEC958 CS8427 Error Status",
        .access =       (SNDRV_CTL_ELEM_ACCESS_READ |
                         SNDRV_CTL_ELEM_ACCESS_VOLATILE),
        .get =          snd_cs8427_in_status_get,
        .private_value = 16,
},
{
        .access =       SNDRV_CTL_ELEM_ACCESS_READ,
        .iface =        SNDRV_CTL_ELEM_IFACE_PCM,
        .name =         SNDRV_CTL_NAME_IEC958("",PLAYBACK,MASK),
        .info =         snd_cs8427_spdif_mask_info,
        .get =          snd_cs8427_spdif_mask_get,
},
{
        .iface =        SNDRV_CTL_ELEM_IFACE_PCM,
        .name =         SNDRV_CTL_NAME_IEC958("",PLAYBACK,DEFAULT),
        .info =         snd_cs8427_spdif_info,
        .get =          snd_cs8427_spdif_get,
        .put =          snd_cs8427_spdif_put,
        .private_value = 0
},
{
        .access =       (SNDRV_CTL_ELEM_ACCESS_READWRITE |
                         SNDRV_CTL_ELEM_ACCESS_INACTIVE),
        .iface =        SNDRV_CTL_ELEM_IFACE_PCM,
        .name =         SNDRV_CTL_NAME_IEC958("",PLAYBACK,PCM_STREAM),
        .info =         snd_cs8427_spdif_info,
        .get =          snd_cs8427_spdif_get,
        .put =          snd_cs8427_spdif_put,
        .private_value = 1
},
{
        .iface =        SNDRV_CTL_ELEM_IFACE_PCM,
        .info =         snd_cs8427_qsubcode_info,
        .name =         "IEC958 Q-subcode Capture Default",
        .access =       (SNDRV_CTL_ELEM_ACCESS_READ |
                         SNDRV_CTL_ELEM_ACCESS_VOLATILE),
        .get =          snd_cs8427_qsubcode_get
}};

int snd_cs8427_iec958_build(struct snd_i2c_device *cs8427,
                            struct snd_pcm_substream *play_substream,
                            struct snd_pcm_substream *cap_substream)
{
        struct cs8427 *chip = cs8427->private_data;
        struct snd_kcontrol *kctl;
        unsigned int idx;
        int err;

        if (snd_BUG_ON(!play_substream || !cap_substream))
                return -EINVAL;
        for (idx = 0; idx < ARRAY_SIZE(snd_cs8427_iec958_controls); idx++) {
                kctl = snd_ctl_new1(&snd_cs8427_iec958_controls[idx], cs8427);
                if (kctl == NULL)
                        return -ENOMEM;
                kctl->id.device = play_substream->pcm->device;
                kctl->id.subdevice = play_substream->number;
                err = snd_ctl_add(cs8427->bus->card, kctl);
                if (err < 0)
                        return err;
                if (! strcmp(kctl->id.name,
                             SNDRV_CTL_NAME_IEC958("",PLAYBACK,PCM_STREAM)))
                        chip->playback.pcm_ctl = kctl;
        }

        chip->playback.substream = play_substream;
        chip->capture.substream = cap_substream;
        if (snd_BUG_ON(!chip->playback.pcm_ctl))
                return -EIO;
        return 0;
}

EXPORT_SYMBOL(snd_cs8427_iec958_build);

int snd_cs8427_iec958_active(struct snd_i2c_device *cs8427, int active)
{
        struct cs8427 *chip;

        if (snd_BUG_ON(!cs8427))
                return -ENXIO;
        chip = cs8427->private_data;
        if (active)
                memcpy(chip->playback.pcm_status,
                       chip->playback.def_status, 24);
        chip->playback.pcm_ctl->vd[0].access &= ~SNDRV_CTL_ELEM_ACCESS_INACTIVE;
        snd_ctl_notify(cs8427->bus->card,
                       SNDRV_CTL_EVENT_MASK_VALUE | SNDRV_CTL_EVENT_MASK_INFO,
                       &chip->playback.pcm_ctl->id);
        return 0;
}

EXPORT_SYMBOL(snd_cs8427_iec958_active);

int snd_cs8427_iec958_pcm(struct snd_i2c_device *cs8427, unsigned int rate)
{
        struct cs8427 *chip;
        char *status;
        int err, reset;

        if (snd_BUG_ON(!cs8427))
                return -ENXIO;
        chip = cs8427->private_data;
        status = chip->playback.pcm_status;
        snd_i2c_lock(cs8427->bus);
        if (status[0] & IEC958_AES0_PROFESSIONAL) {
                status[0] &= ~IEC958_AES0_PRO_FS;
                switch (rate) {
                case 32000: status[0] |= IEC958_AES0_PRO_FS_32000; break;
                case 44100: status[0] |= IEC958_AES0_PRO_FS_44100; break;
                case 48000: status[0] |= IEC958_AES0_PRO_FS_48000; break;
                default: status[0] |= IEC958_AES0_PRO_FS_NOTID; break;
                }
        } else {
                status[3] &= ~IEC958_AES3_CON_FS;
                switch (rate) {
                case 32000: status[3] |= IEC958_AES3_CON_FS_32000; break;
                case 44100: status[3] |= IEC958_AES3_CON_FS_44100; break;
                case 48000: status[3] |= IEC958_AES3_CON_FS_48000; break;
                }
        }
        err = snd_cs8427_send_corudata(cs8427, 0, status, 24);
        if (err > 0)
                snd_ctl_notify(cs8427->bus->card,
                               SNDRV_CTL_EVENT_MASK_VALUE,
                               &chip->playback.pcm_ctl->id);
        reset = chip->rate != rate;
        chip->rate = rate;
        snd_i2c_unlock(cs8427->bus);
        if (reset)
                snd_cs8427_reset(cs8427);
        return err < 0 ? err : 0;
}

EXPORT_SYMBOL(snd_cs8427_iec958_pcm);

static int __init alsa_cs8427_module_init(void)
{
        return 0;
}

static void __exit alsa_cs8427_module_exit(void)
{
}

module_init(alsa_cs8427_module_init)
module_exit(alsa_cs8427_module_exit)