em28xx-audio.c

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/*
 *  Empiatech em28x1 audio extension
 *
 *  Copyright (C) 2006 Markus Rechberger <[email protected]>
 *
 *  Copyright (C) 2007-2011 Mauro Carvalho Chehab <[email protected]>
 *  - Port to work with the in-kernel driver
 *  - Cleanups, fixes, alsa-controls, etc.
 *
 *  This driver is based on my previous au600 usb pstn audio driver
 *  and inherits all the copyrights
 *
 *  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., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include <linux/kernel.h>
#include <linux/usb.h>
#include <linux/init.h>
#include <linux/sound.h>
#include <linux/spinlock.h>
#include <linux/soundcard.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/proc_fs.h>
#include <linux/module.h>
#include <sound/core.h>
#include <sound/pcm.h>
#include <sound/pcm_params.h>
#include <sound/info.h>
#include <sound/initval.h>
#include <sound/control.h>
#include <sound/tlv.h>
#include <sound/ac97_codec.h>
#include <media/v4l2-common.h>
#include "em28xx.h"

static int debug;
module_param(debug, int, 0644);
MODULE_PARM_DESC(debug, "activates debug info");

#define dprintk(fmt, arg...) do {                   \
        if (debug)                          \
        printk(KERN_INFO "em28xx-audio %s: " fmt,       \
                  __func__, ##arg);         \
    } while (0)

static int index[SNDRV_CARDS] = SNDRV_DEFAULT_IDX;

static int em28xx_deinit_isoc_audio(struct em28xx *dev)
{
    int i;

    dprintk("Stopping isoc\n");
    for (i = 0; i < EM28XX_AUDIO_BUFS; i++) {
        if (!irqs_disabled())
            usb_kill_urb(dev->adev.urb[i]);
        else
            usb_unlink_urb(dev->adev.urb[i]);

        usb_free_urb(dev->adev.urb[i]);
        dev->adev.urb[i] = NULL;

        kfree(dev->adev.transfer_buffer[i]);
        dev->adev.transfer_buffer[i] = NULL;
    }

    return 0;
}

static void em28xx_audio_isocirq(struct urb *urb)
{
    struct em28xx            *dev = urb->context;
    int                      i;
    unsigned int             oldptr;
    int                      period_elapsed = 0;
    int                      status;
    unsigned char            *cp;
    unsigned int             stride;
    struct snd_pcm_substream *substream;
    struct snd_pcm_runtime   *runtime;

    switch (urb->status) {
    case 0:             /* success */
    case -ETIMEDOUT:    /* NAK */
        break;
    case -ECONNRESET:   /* kill */
    case -ENOENT:
    case -ESHUTDOWN:
        return;
    default:            /* error */
        dprintk("urb completition error %d.\n", urb->status);
        break;
    }

    if (atomic_read(&dev->stream_started) == 0)
        return;

    if (dev->adev.capture_pcm_substream) {
        substream = dev->adev.capture_pcm_substream;
        runtime = substream->runtime;
        stride = runtime->frame_bits >> 3;

        for (i = 0; i < urb->number_of_packets; i++) {
            int length =
                urb->iso_frame_desc[i].actual_length / stride;
            cp = (unsigned char *)urb->transfer_buffer +
                urb->iso_frame_desc[i].offset;

            if (!length)
                continue;

            oldptr = dev->adev.hwptr_done_capture;
            if (oldptr + length >= runtime->buffer_size) {
                unsigned int cnt =
                    runtime->buffer_size - oldptr;
                memcpy(runtime->dma_area + oldptr * stride, cp,
                       cnt * stride);
                memcpy(runtime->dma_area, cp + cnt * stride,
                       length * stride - cnt * stride);
            } else {
                memcpy(runtime->dma_area + oldptr * stride, cp,
                       length * stride);
            }

            snd_pcm_stream_lock(substream);

            dev->adev.hwptr_done_capture += length;
            if (dev->adev.hwptr_done_capture >=
                runtime->buffer_size)
                dev->adev.hwptr_done_capture -=
                    runtime->buffer_size;

            dev->adev.capture_transfer_done += length;
            if (dev->adev.capture_transfer_done >=
                runtime->period_size) {
                dev->adev.capture_transfer_done -=
                    runtime->period_size;
                period_elapsed = 1;
            }

            snd_pcm_stream_unlock(substream);
        }
        if (period_elapsed)
            snd_pcm_period_elapsed(substream);
    }
    urb->status = 0;

    status = usb_submit_urb(urb, GFP_ATOMIC);
    if (status < 0) {
        em28xx_errdev("resubmit of audio urb failed (error=%i)\n",
                  status);
    }
    return;
}

static int em28xx_init_audio_isoc(struct em28xx *dev)
{
    int       i, errCode;
    const int sb_size = EM28XX_NUM_AUDIO_PACKETS *
                EM28XX_AUDIO_MAX_PACKET_SIZE;

    dprintk("Starting isoc transfers\n");

    for (i = 0; i < EM28XX_AUDIO_BUFS; i++) {
        struct urb *urb;
        int j, k;

        dev->adev.transfer_buffer[i] = kmalloc(sb_size, GFP_ATOMIC);
        if (!dev->adev.transfer_buffer[i])
            return -ENOMEM;

        memset(dev->adev.transfer_buffer[i], 0x80, sb_size);
        urb = usb_alloc_urb(EM28XX_NUM_AUDIO_PACKETS, GFP_ATOMIC);
        if (!urb) {
            em28xx_errdev("usb_alloc_urb failed!\n");
            for (j = 0; j < i; j++) {
                usb_free_urb(dev->adev.urb[j]);
                kfree(dev->adev.transfer_buffer[j]);
            }
            return -ENOMEM;
        }

        urb->dev = dev->udev;
        urb->context = dev;
        urb->pipe = usb_rcvisocpipe(dev->udev, EM28XX_EP_AUDIO);
        urb->transfer_flags = URB_ISO_ASAP;
        urb->transfer_buffer = dev->adev.transfer_buffer[i];
        urb->interval = 1;
        urb->complete = em28xx_audio_isocirq;
        urb->number_of_packets = EM28XX_NUM_AUDIO_PACKETS;
        urb->transfer_buffer_length = sb_size;

        for (j = k = 0; j < EM28XX_NUM_AUDIO_PACKETS;
                 j++, k += EM28XX_AUDIO_MAX_PACKET_SIZE) {
            urb->iso_frame_desc[j].offset = k;
            urb->iso_frame_desc[j].length =
                EM28XX_AUDIO_MAX_PACKET_SIZE;
        }
        dev->adev.urb[i] = urb;
    }

    for (i = 0; i < EM28XX_AUDIO_BUFS; i++) {
        errCode = usb_submit_urb(dev->adev.urb[i], GFP_ATOMIC);
        if (errCode) {
            em28xx_errdev("submit of audio urb failed\n");
            em28xx_deinit_isoc_audio(dev);
            atomic_set(&dev->stream_started, 0);
            return errCode;
        }

    }

    return 0;
}

static int snd_pcm_alloc_vmalloc_buffer(struct snd_pcm_substream *subs,
                    size_t size)
{
    struct snd_pcm_runtime *runtime = subs->runtime;

    dprintk("Allocating vbuffer\n");
    if (runtime->dma_area) {
        if (runtime->dma_bytes > size)
            return 0;

        vfree(runtime->dma_area);
    }
    runtime->dma_area = vmalloc(size);
    if (!runtime->dma_area)
        return -ENOMEM;

    runtime->dma_bytes = size;

    return 0;
}

static struct snd_pcm_hardware snd_em28xx_hw_capture = {
    .info = SNDRV_PCM_INFO_BLOCK_TRANSFER |
        SNDRV_PCM_INFO_MMAP           |
        SNDRV_PCM_INFO_INTERLEAVED    |
        SNDRV_PCM_INFO_BATCH          |
        SNDRV_PCM_INFO_MMAP_VALID,

    .formats = SNDRV_PCM_FMTBIT_S16_LE,

    .rates = SNDRV_PCM_RATE_CONTINUOUS | SNDRV_PCM_RATE_KNOT,

    .rate_min = 48000,
    .rate_max = 48000,
    .channels_min = 2,
    .channels_max = 2,
    .buffer_bytes_max = 62720 * 8,  /* just about the value in usbaudio.c */
    .period_bytes_min = 64,     /* 12544/2, */
    .period_bytes_max = 12544,
    .periods_min = 2,
    .periods_max = 98,      /* 12544, */
};

static int snd_em28xx_capture_open(struct snd_pcm_substream *substream)
{
    struct em28xx *dev = snd_pcm_substream_chip(substream);
    struct snd_pcm_runtime *runtime = substream->runtime;
    int ret = 0;

    dprintk("opening device and trying to acquire exclusive lock\n");

    if (!dev) {
        em28xx_err("BUG: em28xx can't find device struct."
                " Can't proceed with open\n");
        return -ENODEV;
    }

    runtime->hw = snd_em28xx_hw_capture;
    if ((dev->alt == 0 || dev->audio_ifnum) && dev->adev.users == 0) {
        if (dev->audio_ifnum)
            dev->alt = 1;
        else
            dev->alt = 7;

        dprintk("changing alternate number on interface %d to %d\n",
            dev->audio_ifnum, dev->alt);
        usb_set_interface(dev->udev, dev->audio_ifnum, dev->alt);

        /* Sets volume, mute, etc */
        dev->mute = 0;
        mutex_lock(&dev->lock);
        ret = em28xx_audio_analog_set(dev);
        if (ret < 0)
            goto err;

        dev->adev.users++;
        mutex_unlock(&dev->lock);
    }

    snd_pcm_hw_constraint_integer(runtime, SNDRV_PCM_HW_PARAM_PERIODS);
    dev->adev.capture_pcm_substream = substream;

    return 0;
err:
    mutex_unlock(&dev->lock);

    em28xx_err("Error while configuring em28xx mixer\n");
    return ret;
}

static int snd_em28xx_pcm_close(struct snd_pcm_substream *substream)
{
    struct em28xx *dev = snd_pcm_substream_chip(substream);

    dprintk("closing device\n");

    dev->mute = 1;
    mutex_lock(&dev->lock);
    dev->adev.users--;
    if (atomic_read(&dev->stream_started) > 0) {
        atomic_set(&dev->stream_started, 0);
        schedule_work(&dev->wq_trigger);
    }

    em28xx_audio_analog_set(dev);
    if (substream->runtime->dma_area) {
        dprintk("freeing\n");
        vfree(substream->runtime->dma_area);
        substream->runtime->dma_area = NULL;
    }
    mutex_unlock(&dev->lock);

    return 0;
}

static int snd_em28xx_hw_capture_params(struct snd_pcm_substream *substream,
                    struct snd_pcm_hw_params *hw_params)
{
    int ret;

    dprintk("Setting capture parameters\n");

    ret = snd_pcm_alloc_vmalloc_buffer(substream,
                params_buffer_bytes(hw_params));
    if (ret < 0)
        return ret;
#if 0
    /* TODO: set up em28xx audio chip to deliver the correct audio format,
       current default is 48000hz multiplexed => 96000hz mono
       which shouldn't matter since analogue TV only supports mono */
    unsigned int channels, rate, format;

    format = params_format(hw_params);
    rate = params_rate(hw_params);
    channels = params_channels(hw_params);
#endif

    return 0;
}

static int snd_em28xx_hw_capture_free(struct snd_pcm_substream *substream)
{
    struct em28xx *dev = snd_pcm_substream_chip(substream);

    dprintk("Stop capture, if needed\n");

    if (atomic_read(&dev->stream_started) > 0) {
        atomic_set(&dev->stream_started, 0);
        schedule_work(&dev->wq_trigger);
    }

    return 0;
}

static int snd_em28xx_prepare(struct snd_pcm_substream *substream)
{
    struct em28xx *dev = snd_pcm_substream_chip(substream);

    dev->adev.hwptr_done_capture = 0;
    dev->adev.capture_transfer_done = 0;

    return 0;
}

static void audio_trigger(struct work_struct *work)
{
    struct em28xx *dev = container_of(work, struct em28xx, wq_trigger);

    if (atomic_read(&dev->stream_started)) {
        dprintk("starting capture");
        em28xx_init_audio_isoc(dev);
    } else {
        dprintk("stopping capture");
        em28xx_deinit_isoc_audio(dev);
    }
}

static int snd_em28xx_capture_trigger(struct snd_pcm_substream *substream,
                      int cmd)
{
    struct em28xx *dev = snd_pcm_substream_chip(substream);
    int retval = 0;

    switch (cmd) {
    case SNDRV_PCM_TRIGGER_PAUSE_RELEASE: /* fall through */
    case SNDRV_PCM_TRIGGER_RESUME: /* fall through */
    case SNDRV_PCM_TRIGGER_START:
        atomic_set(&dev->stream_started, 1);
        break;
    case SNDRV_PCM_TRIGGER_PAUSE_PUSH: /* fall through */
    case SNDRV_PCM_TRIGGER_SUSPEND: /* fall through */
    case SNDRV_PCM_TRIGGER_STOP:
        atomic_set(&dev->stream_started, 0);
        break;
    default:
        retval = -EINVAL;
    }
    schedule_work(&dev->wq_trigger);
    return retval;
}

static snd_pcm_uframes_t snd_em28xx_capture_pointer(struct snd_pcm_substream
                            *substream)
{
    unsigned long flags;
    struct em28xx *dev;
    snd_pcm_uframes_t hwptr_done;

    dev = snd_pcm_substream_chip(substream);
    spin_lock_irqsave(&dev->adev.slock, flags);
    hwptr_done = dev->adev.hwptr_done_capture;
    spin_unlock_irqrestore(&dev->adev.slock, flags);

    return hwptr_done;
}

static struct page *snd_pcm_get_vmalloc_page(struct snd_pcm_substream *subs,
                         unsigned long offset)
{
    void *pageptr = subs->runtime->dma_area + offset;

    return vmalloc_to_page(pageptr);
}

/*
 * AC97 volume control support
 */
static int em28xx_vol_info(struct snd_kcontrol *kcontrol,
                struct snd_ctl_elem_info *info)
{
    info->type = SNDRV_CTL_ELEM_TYPE_INTEGER;
    info->count = 2;
    info->value.integer.min = 0;
    info->value.integer.max = 0x1f;

    return 0;
}

static int em28xx_vol_put(struct snd_kcontrol *kcontrol,
                   struct snd_ctl_elem_value *value)
{
    struct em28xx *dev = snd_kcontrol_chip(kcontrol);
    u16 val = (0x1f - (value->value.integer.value[0] & 0x1f)) |
          (0x1f - (value->value.integer.value[1] & 0x1f)) << 8;
    int rc;

    mutex_lock(&dev->lock);
    rc = em28xx_read_ac97(dev, kcontrol->private_value);
    if (rc < 0)
        goto err;

    val |= rc & 0x8000; /* Preserve the mute flag */

    rc = em28xx_write_ac97(dev, kcontrol->private_value, val);
    if (rc < 0)
        goto err;

    dprintk("%sleft vol %d, right vol %d (0x%04x) to ac97 volume control 0x%04x\n",
        (val & 0x8000) ? "muted " : "",
        0x1f - ((val >> 8) & 0x1f), 0x1f - (val & 0x1f),
        val, (int)kcontrol->private_value);

err:
    mutex_unlock(&dev->lock);
    return rc;
}

static int em28xx_vol_get(struct snd_kcontrol *kcontrol,
                   struct snd_ctl_elem_value *value)
{
    struct em28xx *dev = snd_kcontrol_chip(kcontrol);
    int val;

    mutex_lock(&dev->lock);
    val = em28xx_read_ac97(dev, kcontrol->private_value);
    mutex_unlock(&dev->lock);
    if (val < 0)
        return val;

    dprintk("%sleft vol %d, right vol %d (0x%04x) from ac97 volume control 0x%04x\n",
        (val & 0x8000) ? "muted " : "",
        0x1f - ((val >> 8) & 0x1f), 0x1f - (val & 0x1f),
        val, (int)kcontrol->private_value);

    value->value.integer.value[0] = 0x1f - (val & 0x1f);
    value->value.integer.value[1] = 0x1f - ((val << 8) & 0x1f);

    return 0;
}

static int em28xx_vol_put_mute(struct snd_kcontrol *kcontrol,
                   struct snd_ctl_elem_value *value)
{
    struct em28xx *dev = snd_kcontrol_chip(kcontrol);
    u16 val = value->value.integer.value[0];
    int rc;

    mutex_lock(&dev->lock);
    rc = em28xx_read_ac97(dev, kcontrol->private_value);
    if (rc < 0)
        goto err;

    if (val)
        rc &= 0x1f1f;
    else
        rc |= 0x8000;

    rc = em28xx_write_ac97(dev, kcontrol->private_value, rc);
    if (rc < 0)
        goto err;

    dprintk("%sleft vol %d, right vol %d (0x%04x) to ac97 volume control 0x%04x\n",
        (val & 0x8000) ? "muted " : "",
        0x1f - ((val >> 8) & 0x1f), 0x1f - (val & 0x1f),
        val, (int)kcontrol->private_value);

err:
    mutex_unlock(&dev->lock);
    return rc;
}

static int em28xx_vol_get_mute(struct snd_kcontrol *kcontrol,
                   struct snd_ctl_elem_value *value)
{
    struct em28xx *dev = snd_kcontrol_chip(kcontrol);
    int val;

    mutex_lock(&dev->lock);
    val = em28xx_read_ac97(dev, kcontrol->private_value);
    mutex_unlock(&dev->lock);
    if (val < 0)
        return val;

    if (val & 0x8000)
        value->value.integer.value[0] = 0;
    else
        value->value.integer.value[0] = 1;

    dprintk("%sleft vol %d, right vol %d (0x%04x) from ac97 volume control 0x%04x\n",
        (val & 0x8000) ? "muted " : "",
        0x1f - ((val >> 8) & 0x1f), 0x1f - (val & 0x1f),
        val, (int)kcontrol->private_value);

    return 0;
}

static const DECLARE_TLV_DB_SCALE(em28xx_db_scale, -3450, 150, 0);

static int em28xx_cvol_new(struct snd_card *card, struct em28xx *dev,
               char *name, int id)
{
    int err;
    char ctl_name[44];
    struct snd_kcontrol *kctl;
    struct snd_kcontrol_new tmp;

    memset (&tmp, 0, sizeof(tmp));
    tmp.iface = SNDRV_CTL_ELEM_IFACE_MIXER,
    tmp.private_value = id,
    tmp.name  = ctl_name,

    /* Add Mute Control */
    sprintf(ctl_name, "%s Switch", name);
    tmp.get  = em28xx_vol_get_mute;
    tmp.put  = em28xx_vol_put_mute;
    tmp.info = snd_ctl_boolean_mono_info;
    kctl = snd_ctl_new1(&tmp, dev);
    err = snd_ctl_add(card, kctl);
    if (err < 0)
        return err;
    dprintk("Added control %s for ac97 volume control 0x%04x\n",
        ctl_name, id);

    memset (&tmp, 0, sizeof(tmp));
    tmp.iface = SNDRV_CTL_ELEM_IFACE_MIXER,
    tmp.private_value = id,
    tmp.name  = ctl_name,

    /* Add Volume Control */
    sprintf(ctl_name, "%s Volume", name);
    tmp.get   = em28xx_vol_get;
    tmp.put   = em28xx_vol_put;
    tmp.info  = em28xx_vol_info;
    tmp.tlv.p = em28xx_db_scale,
    kctl = snd_ctl_new1(&tmp, dev);
    err = snd_ctl_add(card, kctl);
    if (err < 0)
        return err;
    dprintk("Added control %s for ac97 volume control 0x%04x\n",
        ctl_name, id);

    return 0;
}

/*
 * register/unregister code and data
 */
static struct snd_pcm_ops snd_em28xx_pcm_capture = {
    .open      = snd_em28xx_capture_open,
    .close     = snd_em28xx_pcm_close,
    .ioctl     = snd_pcm_lib_ioctl,
    .hw_params = snd_em28xx_hw_capture_params,
    .hw_free   = snd_em28xx_hw_capture_free,
    .prepare   = snd_em28xx_prepare,
    .trigger   = snd_em28xx_capture_trigger,
    .pointer   = snd_em28xx_capture_pointer,
    .page      = snd_pcm_get_vmalloc_page,
};

static int em28xx_audio_init(struct em28xx *dev)
{
    struct em28xx_audio *adev = &dev->adev;
    struct snd_pcm      *pcm;
    struct snd_card     *card;
    static int          devnr;
    int                 err;

    if (!dev->has_alsa_audio || dev->audio_ifnum < 0) {
        /* This device does not support the extension (in this case
           the device is expecting the snd-usb-audio module or
           doesn't have analog audio support at all) */
        return 0;
    }

    printk(KERN_INFO "em28xx-audio.c: probing for em28xx Audio Vendor Class\n");
    printk(KERN_INFO "em28xx-audio.c: Copyright (C) 2006 Markus "
             "Rechberger\n");
    printk(KERN_INFO "em28xx-audio.c: Copyright (C) 2007-2011 Mauro Carvalho Chehab\n");

    err = snd_card_create(index[devnr], "Em28xx Audio", THIS_MODULE, 0,
                  &card);
    if (err < 0)
        return err;

    spin_lock_init(&adev->slock);
    err = snd_pcm_new(card, "Em28xx Audio", 0, 0, 1, &pcm);
    if (err < 0) {
        snd_card_free(card);
        return err;
    }

    snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_CAPTURE, &snd_em28xx_pcm_capture);
    pcm->info_flags = 0;
    pcm->private_data = dev;
    strcpy(pcm->name, "Empia 28xx Capture");

    snd_card_set_dev(card, &dev->udev->dev);
    strcpy(card->driver, "Em28xx-Audio");
    strcpy(card->shortname, "Em28xx Audio");
    strcpy(card->longname, "Empia Em28xx Audio");

    INIT_WORK(&dev->wq_trigger, audio_trigger);

    if (dev->audio_mode.ac97 != EM28XX_NO_AC97) {
        em28xx_cvol_new(card, dev, "Video", AC97_VIDEO);
        em28xx_cvol_new(card, dev, "Line In", AC97_LINE);
        em28xx_cvol_new(card, dev, "Phone", AC97_PHONE);
        em28xx_cvol_new(card, dev, "Microphone", AC97_MIC);
        em28xx_cvol_new(card, dev, "CD", AC97_CD);
        em28xx_cvol_new(card, dev, "AUX", AC97_AUX);
        em28xx_cvol_new(card, dev, "PCM", AC97_PCM);

        em28xx_cvol_new(card, dev, "Master", AC97_MASTER);
        em28xx_cvol_new(card, dev, "Line", AC97_HEADPHONE);
        em28xx_cvol_new(card, dev, "Mono", AC97_MASTER_MONO);
        em28xx_cvol_new(card, dev, "LFE", AC97_CENTER_LFE_MASTER);
        em28xx_cvol_new(card, dev, "Surround", AC97_SURROUND_MASTER);
    }

    err = snd_card_register(card);
    if (err < 0) {
        snd_card_free(card);
        return err;
    }
    adev->sndcard = card;
    adev->udev = dev->udev;

    return 0;
}

static int em28xx_audio_fini(struct em28xx *dev)
{
    if (dev == NULL)
        return 0;

    if (dev->has_alsa_audio != 1) {
        /* This device does not support the extension (in this case
           the device is expecting the snd-usb-audio module or
           doesn't have analog audio support at all) */
        return 0;
    }

    if (dev->adev.sndcard) {
        snd_card_free(dev->adev.sndcard);
        dev->adev.sndcard = NULL;
    }

    return 0;
}

static struct em28xx_ops audio_ops = {
    .id   = EM28XX_AUDIO,
    .name = "Em28xx Audio Extension",
    .init = em28xx_audio_init,
    .fini = em28xx_audio_fini,
};

static int __init em28xx_alsa_register(void)
{
    return em28xx_register_extension(&audio_ops);
}

static void __exit em28xx_alsa_unregister(void)
{
    em28xx_unregister_extension(&audio_ops);
}

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Markus Rechberger <[email protected]>");
MODULE_AUTHOR("Mauro Carvalho Chehab <[email protected]>");
MODULE_DESCRIPTION("Em28xx Audio driver");

module_init(em28xx_alsa_register);
module_exit(em28xx_alsa_unregister);