// SPDX-License-Identifier: GPL-2.0+
//
// Empiatech em28x1 audio extension
//
// Copyright (C) 2006 Markus Rechberger <mrechberger@gmail.com>
//
// Copyright (C) 2007-2016 Mauro Carvalho Chehab
//      - 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

#include "em28xx.h"

#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/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>

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

#define EM28XX_MAX_AUDIO_BUFS           5
#define EM28XX_MIN_AUDIO_PACKETS        64

#define dprintk(fmt, arg...) do {                                       \
        if (debug)                                              \
                dev_printk(KERN_DEBUG, &dev->intf->dev,                 \
                           "video: %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 < dev->adev.num_urb; i++) {
                struct urb *urb = dev->adev.urb[i];

                if (!irqs_disabled())
                        usb_kill_urb(urb);
                else
                        usb_unlink_urb(urb);
        }

        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;

        if (dev->disconnected) {
                dprintk("device disconnected while streaming. URB status=%d.\n",
                        urb->status);
                atomic_set(&dev->adev.stream_started, 0);
                return;
        }

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

        if (atomic_read(&dev->adev.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++) {
                        unsigned long flags;
                        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_irqsave(substream, flags);

                        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_irqrestore(substream, flags);
                }
                if (period_elapsed)
                        snd_pcm_period_elapsed(substream);
        }
        urb->status = 0;

        status = usb_submit_urb(urb, GFP_ATOMIC);
        if (status < 0)
                dev_err(&dev->intf->dev,
                        "resubmit of audio urb failed (error=%i)\n",
                        status);
}

static int em28xx_init_audio_isoc(struct em28xx *dev)
{
        int       i, err;

        dprintk("Starting isoc transfers\n");

        /* Start streaming */
        for (i = 0; i < dev->adev.num_urb; i++) {
                memset(dev->adev.transfer_buffer[i], 0x80,
                       dev->adev.urb[i]->transfer_buffer_length);

                err = usb_submit_urb(dev->adev.urb[i], GFP_ATOMIC);
                if (err) {
                        dev_err(&dev->intf->dev,
                                "submit of audio urb failed (error=%i)\n",
                                err);
                        em28xx_deinit_isoc_audio(dev);
                        atomic_set(&dev->adev.stream_started, 0);
                        return err;
                }
        }

        return 0;
}

static const 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_48000,

        .rate_min = 48000,
        .rate_max = 48000,
        .channels_min = 2,
        .channels_max = 2,
        .buffer_bytes_max = 62720 * 8,  /* just about the value in usbaudio.c */

        /*
         * The period is 12.288 bytes. Allow a 10% of variation along its
         * value, in order to avoid overruns/underruns due to some clock
         * drift.
         *
         * FIXME: This period assumes 64 packets, and a 48000 PCM rate.
         * Calculate it dynamically.
         */
        .period_bytes_min = 11059,
        .period_bytes_max = 13516,

        .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 nonblock, ret = 0;

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

        if (dev->disconnected)
                return -ENODEV;

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

        nonblock = !!(substream->f_flags & O_NONBLOCK);
        if (nonblock) {
                if (!mutex_trylock(&dev->lock))
                        return -EAGAIN;
        } else {
                mutex_lock(&dev->lock);
        }

        runtime->hw = snd_em28xx_hw_capture;

        if (dev->adev.users == 0) {
                if (!dev->alt || dev->is_audio_only) {
                        struct usb_device *udev;

                        udev = interface_to_usbdev(dev->intf);

                        if (dev->is_audio_only)
                                /* audio is on a separate interface */
                                dev->alt = 1;
                        else
                                /* audio is on the same interface as video */
                                dev->alt = 7;
                                /*
                                 * FIXME: The intention seems to be to select
                                 * the alt setting with the largest
                                 * wMaxPacketSize for the video endpoint.
                                 * At least dev->alt should be used instead, but
                                 * we should probably not touch it at all if it
                                 * is already >0, because wMaxPacketSize of the
                                 * audio endpoints seems to be the same for all.
                                 */
                        dprintk("changing alternate number on interface %d to %d\n",
                                dev->ifnum, dev->alt);
                        usb_set_interface(udev, dev->ifnum, dev->alt);
                }

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

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

        /* Dynamically adjust the period size */
        snd_pcm_hw_constraint_integer(runtime, SNDRV_PCM_HW_PARAM_PERIODS);
        snd_pcm_hw_constraint_minmax(runtime, SNDRV_PCM_HW_PARAM_PERIOD_BYTES,
                                     dev->adev.period * 95 / 100,
                                     dev->adev.period * 105 / 100);

        dev->adev.capture_pcm_substream = substream;

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

        dev_err(&dev->intf->dev,
                "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->adev.stream_started) > 0) {
                atomic_set(&dev->adev.stream_started, 0);
                schedule_work(&dev->adev.wq_trigger);
        }

        em28xx_audio_analog_set(dev);
        mutex_unlock(&dev->lock);
        kref_put(&dev->ref, em28xx_free_device);

        return 0;
}

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

        if (dev->disconnected)
                return -ENODEV;

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

        return 0;
}

static void audio_trigger(struct work_struct *work)
{
        struct em28xx_audio *adev =
                            container_of(work, struct em28xx_audio, wq_trigger);
        struct em28xx *dev = container_of(adev, struct em28xx, adev);

        if (atomic_read(&adev->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;

        if (dev->disconnected)
                return -ENODEV;

        switch (cmd) {
        case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:
        case SNDRV_PCM_TRIGGER_RESUME:
        case SNDRV_PCM_TRIGGER_START:
                atomic_set(&dev->adev.stream_started, 1);
                break;
        case SNDRV_PCM_TRIGGER_PAUSE_PUSH:
        case SNDRV_PCM_TRIGGER_SUSPEND:
        case SNDRV_PCM_TRIGGER_STOP:
                atomic_set(&dev->adev.stream_started, 0);
                break;
        default:
                retval = -EINVAL;
        }
        schedule_work(&dev->adev.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);
        if (dev->disconnected)
                return SNDRV_PCM_POS_XRUN;

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

        return hwptr_done;
}

/*
 * AC97 volume control support
 */
static int em28xx_vol_info(struct snd_kcontrol *kcontrol,
                           struct snd_ctl_elem_info *info)
{
        struct em28xx *dev = snd_kcontrol_chip(kcontrol);

        if (dev->disconnected)
                return -ENODEV;

        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);
        struct snd_pcm_substream *substream = dev->adev.capture_pcm_substream;
        u16 val = (0x1f - (value->value.integer.value[0] & 0x1f)) |
                  (0x1f - (value->value.integer.value[1] & 0x1f)) << 8;
        int nonblock = 0;
        int rc;

        if (dev->disconnected)
                return -ENODEV;

        if (substream)
                nonblock = !!(substream->f_flags & O_NONBLOCK);
        if (nonblock) {
                if (!mutex_trylock(&dev->lock))
                        return -EAGAIN;
        } else {
                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);
        struct snd_pcm_substream *substream = dev->adev.capture_pcm_substream;
        int nonblock = 0;
        int val;

        if (dev->disconnected)
                return -ENODEV;

        if (substream)
                nonblock = !!(substream->f_flags & O_NONBLOCK);
        if (nonblock) {
                if (!mutex_trylock(&dev->lock))
                        return -EAGAIN;
        } else {
                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];
        struct snd_pcm_substream *substream = dev->adev.capture_pcm_substream;
        int nonblock = 0;
        int rc;

        if (dev->disconnected)
                return -ENODEV;

        if (substream)
                nonblock = !!(substream->f_flags & O_NONBLOCK);
        if (nonblock) {
                if (!mutex_trylock(&dev->lock))
                        return -EAGAIN;
        } else {
                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);
        struct snd_pcm_substream *substream = dev->adev.capture_pcm_substream;
        int nonblock = 0;
        int val;

        if (dev->disconnected)
                return -ENODEV;

        if (substream)
                nonblock = !!(substream->f_flags & O_NONBLOCK);
        if (nonblock) {
                if (!mutex_trylock(&dev->lock))
                        return -EAGAIN;
        } else {
                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 const struct snd_pcm_ops snd_em28xx_pcm_capture = {
        .open      = snd_em28xx_capture_open,
        .close     = snd_em28xx_pcm_close,
        .prepare   = snd_em28xx_prepare,
        .trigger   = snd_em28xx_capture_trigger,
        .pointer   = snd_em28xx_capture_pointer,
};

static void em28xx_audio_free_urb(struct em28xx *dev)
{
        struct usb_device *udev = interface_to_usbdev(dev->intf);
        int i;

        for (i = 0; i < dev->adev.num_urb; i++) {
                struct urb *urb = dev->adev.urb[i];

                if (!urb)
                        continue;

                usb_free_coherent(udev, urb->transfer_buffer_length,
                                  dev->adev.transfer_buffer[i],
                                  urb->transfer_dma);

                usb_free_urb(urb);
        }
        kfree(dev->adev.urb);
        kfree(dev->adev.transfer_buffer);
        dev->adev.num_urb = 0;
}

/* high bandwidth multiplier, as encoded in highspeed endpoint descriptors */
static int em28xx_audio_ep_packet_size(struct usb_device *udev,
                                       struct usb_endpoint_descriptor *e)
{
        int size = le16_to_cpu(e->wMaxPacketSize);

        if (udev->speed == USB_SPEED_HIGH)
                return (size & 0x7ff) *  (1 + (((size) >> 11) & 0x03));

        return size & 0x7ff;
}

static int em28xx_audio_urb_init(struct em28xx *dev)
{
        struct usb_interface *intf;
        struct usb_endpoint_descriptor *e, *ep = NULL;
        struct usb_device *udev = interface_to_usbdev(dev->intf);
        int                 i, ep_size, interval, num_urb, npackets;
        int                 urb_size, bytes_per_transfer;
        u8 alt;

        if (dev->ifnum)
                alt = 1;
        else
                alt = 7;

        intf = usb_ifnum_to_if(udev, dev->ifnum);

        if (intf->num_altsetting <= alt) {
                dev_err(&dev->intf->dev, "alt %d doesn't exist on interface %d\n",
                        dev->ifnum, alt);
                return -ENODEV;
        }

        for (i = 0; i < intf->altsetting[alt].desc.bNumEndpoints; i++) {
                e = &intf->altsetting[alt].endpoint[i].desc;
                if (!usb_endpoint_dir_in(e))
                        continue;
                if (e->bEndpointAddress == EM28XX_EP_AUDIO) {
                        ep = e;
                        break;
                }
        }

        if (!ep) {
                dev_err(&dev->intf->dev, "Couldn't find an audio endpoint");
                return -ENODEV;
        }

        ep_size = em28xx_audio_ep_packet_size(udev, ep);
        interval = 1 << (ep->bInterval - 1);

        dev_info(&dev->intf->dev,
                 "Endpoint 0x%02x %s on intf %d alt %d interval = %d, size %d\n",
                 EM28XX_EP_AUDIO, usb_speed_string(udev->speed),
                 dev->ifnum, alt, interval, ep_size);

        /* Calculate the number and size of URBs to better fit the audio samples */

        /*
         * Estimate the number of bytes per DMA transfer.
         *
         * This is given by the bit rate (for now, only 48000 Hz) multiplied
         * by 2 channels and 2 bytes/sample divided by the number of microframe
         * intervals and by the microframe rate (125 us)
         */
        bytes_per_transfer = DIV_ROUND_UP(48000 * 2 * 2, 125 * interval);

        /*
         * Estimate the number of transfer URBs. Don't let it go past the
         * maximum number of URBs that is known to be supported by the device.
         */
        num_urb = DIV_ROUND_UP(bytes_per_transfer, ep_size);
        if (num_urb > EM28XX_MAX_AUDIO_BUFS)
                num_urb = EM28XX_MAX_AUDIO_BUFS;

        /*
         * Now that we know the number of bytes per transfer and the number of
         * URBs, estimate the typical size of an URB, in order to adjust the
         * minimal number of packets.
         */
        urb_size = bytes_per_transfer / num_urb;

        /*
         * Now, calculate the amount of audio packets to be filled on each
         * URB. In order to preserve the old behaviour, use a minimal
         * threshold for this value.
         */
        npackets = EM28XX_MIN_AUDIO_PACKETS;
        if (urb_size > ep_size * npackets)
                npackets = DIV_ROUND_UP(urb_size, ep_size);

        dev_info(&dev->intf->dev,
                 "Number of URBs: %d, with %d packets and %d size\n",
                 num_urb, npackets, urb_size);

        /* Estimate the bytes per period */
        dev->adev.period = urb_size * npackets;

        /* Allocate space to store the number of URBs to be used */

        dev->adev.transfer_buffer = kcalloc(num_urb,
                                            sizeof(*dev->adev.transfer_buffer),
                                            GFP_KERNEL);
        if (!dev->adev.transfer_buffer)
                return -ENOMEM;

        dev->adev.urb = kzalloc_objs(*dev->adev.urb, num_urb);
        if (!dev->adev.urb) {
                kfree(dev->adev.transfer_buffer);
                return -ENOMEM;
        }

        /* Alloc memory for each URB and for each transfer buffer */
        dev->adev.num_urb = num_urb;
        for (i = 0; i < num_urb; i++) {
                struct urb *urb;
                int j, k;
                void *buf;

                urb = usb_alloc_urb(npackets, GFP_KERNEL);
                if (!urb) {
                        em28xx_audio_free_urb(dev);
                        return -ENOMEM;
                }
                dev->adev.urb[i] = urb;

                buf = usb_alloc_coherent(udev, npackets * ep_size, GFP_KERNEL,
                                         &urb->transfer_dma);
                if (!buf) {
                        dev_err(&dev->intf->dev,
                                "usb_alloc_coherent failed!\n");
                        em28xx_audio_free_urb(dev);
                        return -ENOMEM;
                }
                dev->adev.transfer_buffer[i] = buf;

                urb->dev = udev;
                urb->context = dev;
                urb->pipe = usb_rcvisocpipe(udev, EM28XX_EP_AUDIO);
                urb->transfer_flags = URB_ISO_ASAP | URB_NO_TRANSFER_DMA_MAP;
                urb->transfer_buffer = buf;
                urb->interval = interval;
                urb->complete = em28xx_audio_isocirq;
                urb->number_of_packets = npackets;
                urb->transfer_buffer_length = ep_size * npackets;

                for (j = k = 0; j < npackets; j++, k += ep_size) {
                        urb->iso_frame_desc[j].offset = k;
                        urb->iso_frame_desc[j].length = ep_size;
                }
        }

        return 0;
}

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

        if (dev->usb_audio_type != EM28XX_USB_AUDIO_VENDOR) {
                /*
                 * 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;
        }

        dev_info(&dev->intf->dev, "Binding audio extension\n");

        kref_get(&dev->ref);

        dev_info(&dev->intf->dev,
                 "em28xx-audio.c: Copyright (C) 2006 Markus Rechberger\n");
        dev_info(&dev->intf->dev,
                 "em28xx-audio.c: Copyright (C) 2007-2016 Mauro Carvalho Chehab\n");

        err = snd_card_new(&dev->intf->dev, index[devnr], "Em28xx Audio",
                           THIS_MODULE, 0, &card);
        if (err < 0)
                return err;

        spin_lock_init(&adev->slock);
        adev->sndcard = card;
        adev->udev = udev;

        err = snd_pcm_new(card, "Em28xx Audio", 0, 0, 1, &pcm);
        if (err < 0)
                goto card_free;

        snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_CAPTURE, &snd_em28xx_pcm_capture);
        snd_pcm_set_managed_buffer_all(pcm, SNDRV_DMA_TYPE_VMALLOC, NULL, 0, 0);
        pcm->info_flags = 0;
        pcm->private_data = dev;
        strscpy(pcm->name, "Empia 28xx Capture", sizeof(pcm->name));

        strscpy(card->driver, "Em28xx-Audio", sizeof(card->driver));
        strscpy(card->shortname, "Em28xx Audio", sizeof(card->shortname));
        strscpy(card->longname, "Empia Em28xx Audio", sizeof(card->longname));

        INIT_WORK(&adev->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 = em28xx_audio_urb_init(dev);
        if (err)
                goto card_free;

        err = snd_card_register(card);
        if (err < 0)
                goto urb_free;

        dev_info(&dev->intf->dev, "Audio extension successfully initialized\n");
        return 0;

urb_free:
        em28xx_audio_free_urb(dev);

card_free:
        snd_card_free(card);
        adev->sndcard = NULL;

        return err;
}

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

        if (dev->usb_audio_type != EM28XX_USB_AUDIO_VENDOR) {
                /*
                 * 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;
        }

        dev_info(&dev->intf->dev, "Closing audio extension\n");

        if (dev->adev.sndcard) {
                snd_card_disconnect(dev->adev.sndcard);
                flush_work(&dev->adev.wq_trigger);

                em28xx_audio_free_urb(dev);

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

        kref_put(&dev->ref, em28xx_free_device);
        return 0;
}

static int em28xx_audio_suspend(struct em28xx *dev)
{
        if (!dev)
                return 0;

        if (dev->usb_audio_type != EM28XX_USB_AUDIO_VENDOR)
                return 0;

        dev_info(&dev->intf->dev, "Suspending audio extension\n");
        em28xx_deinit_isoc_audio(dev);
        atomic_set(&dev->adev.stream_started, 0);
        return 0;
}

static int em28xx_audio_resume(struct em28xx *dev)
{
        if (!dev)
                return 0;

        if (dev->usb_audio_type != EM28XX_USB_AUDIO_VENDOR)
                return 0;

        dev_info(&dev->intf->dev, "Resuming audio extension\n");
        /* Nothing to do other than schedule_work() ?? */
        schedule_work(&dev->adev.wq_trigger);
        return 0;
}

static struct em28xx_ops audio_ops = {
        .id   = EM28XX_AUDIO,
        .name = "Em28xx Audio Extension",
        .init = em28xx_audio_init,
        .fini = em28xx_audio_fini,
        .suspend = em28xx_audio_suspend,
        .resume = em28xx_audio_resume,
};

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 v2");
MODULE_AUTHOR("Markus Rechberger <mrechberger@gmail.com>");
MODULE_AUTHOR("Mauro Carvalho Chehab");
MODULE_DESCRIPTION(DRIVER_DESC " - audio interface");
MODULE_VERSION(EM28XX_VERSION);

module_init(em28xx_alsa_register);
module_exit(em28xx_alsa_unregister);