// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *   (Tentative) USB Audio Driver for ALSA
 *
 *   Copyright (c) 2002 by Takashi Iwai <tiwai@suse.de>
 *
 *   Many codes borrowed from audio.c by
 *          Alan Cox (alan@lxorguk.ukuu.org.uk)
 *          Thomas Sailer (sailer@ife.ee.ethz.ch)
 *
 *   Audio Class 3.0 support by Ruslan Bilovol <ruslan.bilovol@gmail.com>
 *
 *  NOTES:
 *
 *   - the linked URBs would be preferred but not used so far because of
 *     the instability of unlinking.
 *   - type II is not supported properly.  there is no device which supports
 *     this type *correctly*.  SB extigy looks as if it supports, but it's
 *     indeed an AC3 stream packed in SPDIF frames (i.e. no real AC3 stream).
 */


#include <linux/bitops.h>
#include <linux/init.h>
#include <linux/list.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/ctype.h>
#include <linux/usb.h>
#include <linux/moduleparam.h>
#include <linux/mutex.h>
#include <linux/usb/audio.h>
#include <linux/usb/audio-v2.h>
#include <linux/usb/audio-v3.h>
#include <linux/module.h>

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

#include "usbaudio.h"
#include "card.h"
#include "midi.h"
#include "mixer.h"
#include "proc.h"
#include "quirks.h"
#include "endpoint.h"
#include "helper.h"
#include "debug.h"
#include "pcm.h"
#include "format.h"
#include "power.h"
#include "stream.h"
#include "media.h"

MODULE_AUTHOR("Takashi Iwai <tiwai@suse.de>");
MODULE_DESCRIPTION("USB Audio");
MODULE_LICENSE("GPL");
MODULE_SUPPORTED_DEVICE("{{Generic,USB Audio}}");


static int index[SNDRV_CARDS] = SNDRV_DEFAULT_IDX;      /* Index 0-MAX */
static char *id[SNDRV_CARDS] = SNDRV_DEFAULT_STR;       /* ID for this card */
static bool enable[SNDRV_CARDS] = SNDRV_DEFAULT_ENABLE_PNP;/* Enable this card */
/* Vendor/product IDs for this card */
static int vid[SNDRV_CARDS] = { [0 ... (SNDRV_CARDS-1)] = -1 };
static int pid[SNDRV_CARDS] = { [0 ... (SNDRV_CARDS-1)] = -1 };
static int device_setup[SNDRV_CARDS]; /* device parameter for this card */
static bool ignore_ctl_error;
static bool autoclock = true;
static char *quirk_alias[SNDRV_CARDS];
static char *delayed_register[SNDRV_CARDS];

bool snd_usb_use_vmalloc = true;
bool snd_usb_skip_validation;

module_param_array(index, int, NULL, 0444);
MODULE_PARM_DESC(index, "Index value for the USB audio adapter.");
module_param_array(id, charp, NULL, 0444);
MODULE_PARM_DESC(id, "ID string for the USB audio adapter.");
module_param_array(enable, bool, NULL, 0444);
MODULE_PARM_DESC(enable, "Enable USB audio adapter.");
module_param_array(vid, int, NULL, 0444);
MODULE_PARM_DESC(vid, "Vendor ID for the USB audio device.");
module_param_array(pid, int, NULL, 0444);
MODULE_PARM_DESC(pid, "Product ID for the USB audio device.");
module_param_array(device_setup, int, NULL, 0444);
MODULE_PARM_DESC(device_setup, "Specific device setup (if needed).");
module_param(ignore_ctl_error, bool, 0444);
MODULE_PARM_DESC(ignore_ctl_error,
                 "Ignore errors from USB controller for mixer interfaces.");
module_param(autoclock, bool, 0444);
MODULE_PARM_DESC(autoclock, "Enable auto-clock selection for UAC2 devices (default: yes).");
module_param_array(quirk_alias, charp, NULL, 0444);
MODULE_PARM_DESC(quirk_alias, "Quirk aliases, e.g. 0123abcd:5678beef.");
module_param_array(delayed_register, charp, NULL, 0444);
MODULE_PARM_DESC(delayed_register, "Quirk for delayed registration, given by id:iface, e.g. 0123abcd:4.");
module_param_named(use_vmalloc, snd_usb_use_vmalloc, bool, 0444);
MODULE_PARM_DESC(use_vmalloc, "Use vmalloc for PCM intermediate buffers (default: yes).");
module_param_named(skip_validation, snd_usb_skip_validation, bool, 0444);
MODULE_PARM_DESC(skip_validation, "Skip unit descriptor validation (default: no).");

/*
 * we keep the snd_usb_audio_t instances by ourselves for merging
 * the all interfaces on the same card as one sound device.
 */

static DEFINE_MUTEX(register_mutex);
static struct snd_usb_audio *usb_chip[SNDRV_CARDS];
static struct usb_driver usb_audio_driver;

/*
 * disconnect streams
 * called from usb_audio_disconnect()
 */
static void snd_usb_stream_disconnect(struct snd_usb_stream *as)
{
        int idx;
        struct snd_usb_substream *subs;

        for (idx = 0; idx < 2; idx++) {
                subs = &as->substream[idx];
                if (!subs->num_formats)
                        continue;
                subs->interface = -1;
                subs->data_endpoint = NULL;
                subs->sync_endpoint = NULL;
        }
}

static int snd_usb_create_stream(struct snd_usb_audio *chip, int ctrlif, int interface)
{
        struct usb_device *dev = chip->dev;
        struct usb_host_interface *alts;
        struct usb_interface_descriptor *altsd;
        struct usb_interface *iface = usb_ifnum_to_if(dev, interface);

        if (!iface) {
                dev_err(&dev->dev, "%u:%d : does not exist\n",
                        ctrlif, interface);
                return -EINVAL;
        }

        alts = &iface->altsetting[0];
        altsd = get_iface_desc(alts);

        /*
         * Android with both accessory and audio interfaces enabled gets the
         * interface numbers wrong.
         */
        if ((chip->usb_id == USB_ID(0x18d1, 0x2d04) ||
             chip->usb_id == USB_ID(0x18d1, 0x2d05)) &&
            interface == 0 &&
            altsd->bInterfaceClass == USB_CLASS_VENDOR_SPEC &&
            altsd->bInterfaceSubClass == USB_SUBCLASS_VENDOR_SPEC) {
                interface = 2;
                iface = usb_ifnum_to_if(dev, interface);
                if (!iface)
                        return -EINVAL;
                alts = &iface->altsetting[0];
                altsd = get_iface_desc(alts);
        }

        if (usb_interface_claimed(iface)) {
                dev_dbg(&dev->dev, "%d:%d: skipping, already claimed\n",
                        ctrlif, interface);
                return -EINVAL;
        }

        if ((altsd->bInterfaceClass == USB_CLASS_AUDIO ||
             altsd->bInterfaceClass == USB_CLASS_VENDOR_SPEC) &&
            altsd->bInterfaceSubClass == USB_SUBCLASS_MIDISTREAMING) {
                int err = __snd_usbmidi_create(chip->card, iface,
                                             &chip->midi_list, NULL,
                                             chip->usb_id);
                if (err < 0) {
                        dev_err(&dev->dev,
                                "%u:%d: cannot create sequencer device\n",
                                ctrlif, interface);
                        return -EINVAL;
                }
                usb_driver_claim_interface(&usb_audio_driver, iface, (void *)-1L);

                return 0;
        }

        if ((altsd->bInterfaceClass != USB_CLASS_AUDIO &&
             altsd->bInterfaceClass != USB_CLASS_VENDOR_SPEC) ||
            altsd->bInterfaceSubClass != USB_SUBCLASS_AUDIOSTREAMING) {
                dev_dbg(&dev->dev,
                        "%u:%d: skipping non-supported interface %d\n",
                        ctrlif, interface, altsd->bInterfaceClass);
                /* skip non-supported classes */
                return -EINVAL;
        }

        if (snd_usb_get_speed(dev) == USB_SPEED_LOW) {
                dev_err(&dev->dev, "low speed audio streaming not supported\n");
                return -EINVAL;
        }

        if (! snd_usb_parse_audio_interface(chip, interface)) {
                usb_set_interface(dev, interface, 0); /* reset the current interface */
                usb_driver_claim_interface(&usb_audio_driver, iface, (void *)-1L);
        }

        return 0;
}

/*
 * parse audio control descriptor and create pcm/midi streams
 */
static int snd_usb_create_streams(struct snd_usb_audio *chip, int ctrlif)
{
        struct usb_device *dev = chip->dev;
        struct usb_host_interface *host_iface;
        struct usb_interface_descriptor *altsd;
        int i, protocol;

        /* find audiocontrol interface */
        host_iface = &usb_ifnum_to_if(dev, ctrlif)->altsetting[0];
        altsd = get_iface_desc(host_iface);
        protocol = altsd->bInterfaceProtocol;

        switch (protocol) {
        default:
                dev_warn(&dev->dev,
                         "unknown interface protocol %#02x, assuming v1\n",
                         protocol);
                fallthrough;

        case UAC_VERSION_1: {
                struct uac1_ac_header_descriptor *h1;
                int rest_bytes;

                h1 = snd_usb_find_csint_desc(host_iface->extra,
                                                         host_iface->extralen,
                                                         NULL, UAC_HEADER);
                if (!h1 || h1->bLength < sizeof(*h1)) {
                        dev_err(&dev->dev, "cannot find UAC_HEADER\n");
                        return -EINVAL;
                }

                rest_bytes = (void *)(host_iface->extra +
                                host_iface->extralen) - (void *)h1;

                /* just to be sure -- this shouldn't hit at all */
                if (rest_bytes <= 0) {
                        dev_err(&dev->dev, "invalid control header\n");
                        return -EINVAL;
                }

                if (rest_bytes < sizeof(*h1)) {
                        dev_err(&dev->dev, "too short v1 buffer descriptor\n");
                        return -EINVAL;
                }

                if (!h1->bInCollection) {
                        dev_info(&dev->dev, "skipping empty audio interface (v1)\n");
                        return -EINVAL;
                }

                if (rest_bytes < h1->bLength) {
                        dev_err(&dev->dev, "invalid buffer length (v1)\n");
                        return -EINVAL;
                }

                if (h1->bLength < sizeof(*h1) + h1->bInCollection) {
                        dev_err(&dev->dev, "invalid UAC_HEADER (v1)\n");
                        return -EINVAL;
                }

                for (i = 0; i < h1->bInCollection; i++)
                        snd_usb_create_stream(chip, ctrlif, h1->baInterfaceNr[i]);

                break;
        }

        case UAC_VERSION_2:
        case UAC_VERSION_3: {
                struct usb_interface_assoc_descriptor *assoc =
                        usb_ifnum_to_if(dev, ctrlif)->intf_assoc;

                if (!assoc) {
                        /*
                         * Firmware writers cannot count to three.  So to find
                         * the IAD on the NuForce UDH-100, also check the next
                         * interface.
                         */
                        struct usb_interface *iface =
                                usb_ifnum_to_if(dev, ctrlif + 1);
                        if (iface &&
                            iface->intf_assoc &&
                            iface->intf_assoc->bFunctionClass == USB_CLASS_AUDIO &&
                            iface->intf_assoc->bFunctionProtocol == UAC_VERSION_2)
                                assoc = iface->intf_assoc;
                }

                if (!assoc) {
                        dev_err(&dev->dev, "Audio class v2/v3 interfaces need an interface association\n");
                        return -EINVAL;
                }

                if (protocol == UAC_VERSION_3) {
                        int badd = assoc->bFunctionSubClass;

                        if (badd != UAC3_FUNCTION_SUBCLASS_FULL_ADC_3_0 &&
                            (badd < UAC3_FUNCTION_SUBCLASS_GENERIC_IO ||
                             badd > UAC3_FUNCTION_SUBCLASS_SPEAKERPHONE)) {
                                dev_err(&dev->dev,
                                        "Unsupported UAC3 BADD profile\n");
                                return -EINVAL;
                        }

                        chip->badd_profile = badd;
                }

                for (i = 0; i < assoc->bInterfaceCount; i++) {
                        int intf = assoc->bFirstInterface + i;

                        if (intf != ctrlif)
                                snd_usb_create_stream(chip, ctrlif, intf);
                }

                break;
        }
        }

        return 0;
}

/*
 * free the chip instance
 *
 * here we have to do not much, since pcm and controls are already freed
 *
 */

static void snd_usb_audio_free(struct snd_card *card)
{
        struct snd_usb_audio *chip = card->private_data;
        struct snd_usb_endpoint *ep, *n;

        list_for_each_entry_safe(ep, n, &chip->ep_list, list)
                snd_usb_endpoint_free(ep);

        mutex_destroy(&chip->mutex);
        if (!atomic_read(&chip->shutdown))
                dev_set_drvdata(&chip->dev->dev, NULL);
}

static void usb_audio_make_shortname(struct usb_device *dev,
                                     struct snd_usb_audio *chip,
                                     const struct snd_usb_audio_quirk *quirk)
{
        struct snd_card *card = chip->card;

        if (quirk && quirk->product_name && *quirk->product_name) {
                strlcpy(card->shortname, quirk->product_name,
                        sizeof(card->shortname));
                return;
        }

        /* retrieve the device string as shortname */
        if (!dev->descriptor.iProduct ||
            usb_string(dev, dev->descriptor.iProduct,
                       card->shortname, sizeof(card->shortname)) <= 0) {
                /* no name available from anywhere, so use ID */
                sprintf(card->shortname, "USB Device %#04x:%#04x",
                        USB_ID_VENDOR(chip->usb_id),
                        USB_ID_PRODUCT(chip->usb_id));
        }

        strim(card->shortname);
}

static void usb_audio_make_longname(struct usb_device *dev,
                                    struct snd_usb_audio *chip,
                                    const struct snd_usb_audio_quirk *quirk)
{
        struct snd_card *card = chip->card;
        int len;

        /* shortcut - if any pre-defined string is given, use it */
        if (quirk && quirk->profile_name && *quirk->profile_name) {
                strlcpy(card->longname, quirk->profile_name,
                        sizeof(card->longname));
                return;
        }

        if (quirk && quirk->vendor_name && *quirk->vendor_name) {
                len = strlcpy(card->longname, quirk->vendor_name, sizeof(card->longname));
        } else {
                /* retrieve the vendor and device strings as longname */
                if (dev->descriptor.iManufacturer)
                        len = usb_string(dev, dev->descriptor.iManufacturer,
                                         card->longname, sizeof(card->longname));
                else
                        len = 0;
                /* we don't really care if there isn't any vendor string */
        }
        if (len > 0) {
                strim(card->longname);
                if (*card->longname)
                        strlcat(card->longname, " ", sizeof(card->longname));
        }

        strlcat(card->longname, card->shortname, sizeof(card->longname));

        len = strlcat(card->longname, " at ", sizeof(card->longname));

        if (len < sizeof(card->longname))
                usb_make_path(dev, card->longname + len, sizeof(card->longname) - len);

        switch (snd_usb_get_speed(dev)) {
        case USB_SPEED_LOW:
                strlcat(card->longname, ", low speed", sizeof(card->longname));
                break;
        case USB_SPEED_FULL:
                strlcat(card->longname, ", full speed", sizeof(card->longname));
                break;
        case USB_SPEED_HIGH:
                strlcat(card->longname, ", high speed", sizeof(card->longname));
                break;
        case USB_SPEED_SUPER:
                strlcat(card->longname, ", super speed", sizeof(card->longname));
                break;
        case USB_SPEED_SUPER_PLUS:
                strlcat(card->longname, ", super speed plus", sizeof(card->longname));
                break;
        default:
                break;
        }
}

/*
 * create a chip instance and set its names.
 */
static int snd_usb_audio_create(struct usb_interface *intf,
                                struct usb_device *dev, int idx,
                                const struct snd_usb_audio_quirk *quirk,
                                unsigned int usb_id,
                                struct snd_usb_audio **rchip)
{
        struct snd_card *card;
        struct snd_usb_audio *chip;
        int err;
        char component[14];

        *rchip = NULL;

        switch (snd_usb_get_speed(dev)) {
        case USB_SPEED_LOW:
        case USB_SPEED_FULL:
        case USB_SPEED_HIGH:
        case USB_SPEED_WIRELESS:
        case USB_SPEED_SUPER:
        case USB_SPEED_SUPER_PLUS:
                break;
        default:
                dev_err(&dev->dev, "unknown device speed %d\n", snd_usb_get_speed(dev));
                return -ENXIO;
        }

        err = snd_card_new(&intf->dev, index[idx], id[idx], THIS_MODULE,
                           sizeof(*chip), &card);
        if (err < 0) {
                dev_err(&dev->dev, "cannot create card instance %d\n", idx);
                return err;
        }

        chip = card->private_data;
        mutex_init(&chip->mutex);
        init_waitqueue_head(&chip->shutdown_wait);
        chip->index = idx;
        chip->dev = dev;
        chip->card = card;
        chip->setup = device_setup[idx];
        chip->autoclock = autoclock;
        atomic_set(&chip->active, 1); /* avoid autopm during probing */
        atomic_set(&chip->usage_count, 0);
        atomic_set(&chip->shutdown, 0);

        chip->usb_id = usb_id;
        INIT_LIST_HEAD(&chip->pcm_list);
        INIT_LIST_HEAD(&chip->ep_list);
        INIT_LIST_HEAD(&chip->midi_list);
        INIT_LIST_HEAD(&chip->mixer_list);

        card->private_free = snd_usb_audio_free;

        strcpy(card->driver, "USB-Audio");
        sprintf(component, "USB%04x:%04x",
                USB_ID_VENDOR(chip->usb_id), USB_ID_PRODUCT(chip->usb_id));
        snd_component_add(card, component);

        usb_audio_make_shortname(dev, chip, quirk);
        usb_audio_make_longname(dev, chip, quirk);

        snd_usb_audio_create_proc(chip);

        *rchip = chip;
        return 0;
}

/* look for a matching quirk alias id */
static bool get_alias_id(struct usb_device *dev, unsigned int *id)
{
        int i;
        unsigned int src, dst;

        for (i = 0; i < ARRAY_SIZE(quirk_alias); i++) {
                if (!quirk_alias[i] ||
                    sscanf(quirk_alias[i], "%x:%x", &src, &dst) != 2 ||
                    src != *id)
                        continue;
                dev_info(&dev->dev,
                         "device (%04x:%04x): applying quirk alias %04x:%04x\n",
                         USB_ID_VENDOR(*id), USB_ID_PRODUCT(*id),
                         USB_ID_VENDOR(dst), USB_ID_PRODUCT(dst));
                *id = dst;
                return true;
        }

        return false;
}

static bool check_delayed_register_option(struct snd_usb_audio *chip, int iface)
{
        int i;
        unsigned int id, inum;

        for (i = 0; i < ARRAY_SIZE(delayed_register); i++) {
                if (delayed_register[i] &&
                    sscanf(delayed_register[i], "%x:%x", &id, &inum) == 2 &&
                    id == chip->usb_id)
                        return inum != iface;
        }

        return false;
}

static const struct usb_device_id usb_audio_ids[]; /* defined below */

/* look for the corresponding quirk */
static const struct snd_usb_audio_quirk *
get_alias_quirk(struct usb_device *dev, unsigned int id)
{
        const struct usb_device_id *p;

        for (p = usb_audio_ids; p->match_flags; p++) {
                /* FIXME: this checks only vendor:product pair in the list */
                if ((p->match_flags & USB_DEVICE_ID_MATCH_DEVICE) ==
                    USB_DEVICE_ID_MATCH_DEVICE &&
                    p->idVendor == USB_ID_VENDOR(id) &&
                    p->idProduct == USB_ID_PRODUCT(id))
                        return (const struct snd_usb_audio_quirk *)p->driver_info;
        }

        return NULL;
}

/*
 * probe the active usb device
 *
 * note that this can be called multiple times per a device, when it
 * includes multiple audio control interfaces.
 *
 * thus we check the usb device pointer and creates the card instance
 * only at the first time.  the successive calls of this function will
 * append the pcm interface to the corresponding card.
 */
static int usb_audio_probe(struct usb_interface *intf,
                           const struct usb_device_id *usb_id)
{
        struct usb_device *dev = interface_to_usbdev(intf);
        const struct snd_usb_audio_quirk *quirk =
                (const struct snd_usb_audio_quirk *)usb_id->driver_info;
        struct snd_usb_audio *chip;
        int i, err;
        struct usb_host_interface *alts;
        int ifnum;
        u32 id;

        alts = &intf->altsetting[0];
        ifnum = get_iface_desc(alts)->bInterfaceNumber;
        id = USB_ID(le16_to_cpu(dev->descriptor.idVendor),
                    le16_to_cpu(dev->descriptor.idProduct));
        if (get_alias_id(dev, &id))
                quirk = get_alias_quirk(dev, id);
        if (quirk && quirk->ifnum >= 0 && ifnum != quirk->ifnum)
                return -ENXIO;

        err = snd_usb_apply_boot_quirk(dev, intf, quirk, id);
        if (err < 0)
                return err;

        /*
         * found a config.  now register to ALSA
         */

        /* check whether it's already registered */
        chip = NULL;
        mutex_lock(&register_mutex);
        for (i = 0; i < SNDRV_CARDS; i++) {
                if (usb_chip[i] && usb_chip[i]->dev == dev) {
                        if (atomic_read(&usb_chip[i]->shutdown)) {
                                dev_err(&dev->dev, "USB device is in the shutdown state, cannot create a card instance\n");
                                err = -EIO;
                                goto __error;
                        }
                        chip = usb_chip[i];
                        atomic_inc(&chip->active); /* avoid autopm */
                        break;
                }
        }
        if (! chip) {
                err = snd_usb_apply_boot_quirk_once(dev, intf, quirk, id);
                if (err < 0)
                        goto __error;

                /* it's a fresh one.
                 * now look for an empty slot and create a new card instance
                 */
                for (i = 0; i < SNDRV_CARDS; i++)
                        if (!usb_chip[i] &&
                            (vid[i] == -1 || vid[i] == USB_ID_VENDOR(id)) &&
                            (pid[i] == -1 || pid[i] == USB_ID_PRODUCT(id))) {
                                if (enable[i]) {
                                        err = snd_usb_audio_create(intf, dev, i, quirk,
                                                                   id, &chip);
                                        if (err < 0)
                                                goto __error;
                                        break;
                                } else if (vid[i] != -1 || pid[i] != -1) {
                                        dev_info(&dev->dev,
                                                 "device (%04x:%04x) is disabled\n",
                                                 USB_ID_VENDOR(id),
                                                 USB_ID_PRODUCT(id));
                                        err = -ENOENT;
                                        goto __error;
                                }
                        }
                if (!chip) {
                        dev_err(&dev->dev, "no available usb audio device\n");
                        err = -ENODEV;
                        goto __error;
                }
        }

        if (chip->num_interfaces >= MAX_CARD_INTERFACES) {
                dev_info(&dev->dev, "Too many interfaces assigned to the single USB-audio card\n");
                err = -EINVAL;
                goto __error;
        }

        dev_set_drvdata(&dev->dev, chip);

        /*
         * For devices with more than one control interface, we assume the
         * first contains the audio controls. We might need a more specific
         * check here in the future.
         */
        if (!chip->ctrl_intf)
                chip->ctrl_intf = alts;

        chip->txfr_quirk = 0;
        err = 1; /* continue */
        if (quirk && quirk->ifnum != QUIRK_NO_INTERFACE) {
                /* need some special handlings */
                err = snd_usb_create_quirk(chip, intf, &usb_audio_driver, quirk);
                if (err < 0)
                        goto __error;
        }

        if (err > 0) {
                /* create normal USB audio interfaces */
                err = snd_usb_create_streams(chip, ifnum);
                if (err < 0)
                        goto __error;
                err = snd_usb_create_mixer(chip, ifnum, ignore_ctl_error);
                if (err < 0)
                        goto __error;
        }

        if (chip->need_delayed_register) {
                dev_info(&dev->dev,
                         "Found post-registration device assignment: %08x:%02x\n",
                         chip->usb_id, ifnum);
                chip->need_delayed_register = false; /* clear again */
        }

        /* we are allowed to call snd_card_register() many times, but first
         * check to see if a device needs to skip it or do anything special
         */
        if (!snd_usb_registration_quirk(chip, ifnum) &&
            !check_delayed_register_option(chip, ifnum)) {
                err = snd_card_register(chip->card);
                if (err < 0)
                        goto __error;
        }

        if (quirk && quirk->shares_media_device) {
                /* don't want to fail when snd_media_device_create() fails */
                snd_media_device_create(chip, intf);
        }

        usb_chip[chip->index] = chip;
        chip->intf[chip->num_interfaces] = intf;
        chip->num_interfaces++;
        usb_set_intfdata(intf, chip);
        atomic_dec(&chip->active);
        mutex_unlock(&register_mutex);
        return 0;

 __error:
        if (chip) {
                /* chip->active is inside the chip->card object,
                 * decrement before memory is possibly returned.
                 */
                atomic_dec(&chip->active);
                if (!chip->num_interfaces)
                        snd_card_free(chip->card);
        }
        mutex_unlock(&register_mutex);
        return err;
}

/*
 * we need to take care of counter, since disconnection can be called also
 * many times as well as usb_audio_probe().
 */
static void usb_audio_disconnect(struct usb_interface *intf)
{
        struct snd_usb_audio *chip = usb_get_intfdata(intf);
        struct snd_card *card;
        struct list_head *p;

        if (chip == (void *)-1L)
                return;

        card = chip->card;

        mutex_lock(&register_mutex);
        if (atomic_inc_return(&chip->shutdown) == 1) {
                struct snd_usb_stream *as;
                struct snd_usb_endpoint *ep;
                struct usb_mixer_interface *mixer;

                /* wait until all pending tasks done;
                 * they are protected by snd_usb_lock_shutdown()
                 */
                wait_event(chip->shutdown_wait,
                           !atomic_read(&chip->usage_count));
                snd_card_disconnect(card);
                /* release the pcm resources */
                list_for_each_entry(as, &chip->pcm_list, list) {
                        snd_usb_stream_disconnect(as);
                }
                /* release the endpoint resources */
                list_for_each_entry(ep, &chip->ep_list, list) {
                        snd_usb_endpoint_release(ep);
                }
                /* release the midi resources */
                list_for_each(p, &chip->midi_list) {
                        snd_usbmidi_disconnect(p);
                }
                /*
                 * Nice to check quirk && quirk->shares_media_device and
                 * then call the snd_media_device_delete(). Don't have
                 * access to the quirk here. snd_media_device_delete()
                 * accesses mixer_list
                 */
                snd_media_device_delete(chip);

                /* release mixer resources */
                list_for_each_entry(mixer, &chip->mixer_list, list) {
                        snd_usb_mixer_disconnect(mixer);
                }
        }

        chip->num_interfaces--;
        if (chip->num_interfaces <= 0) {
                usb_chip[chip->index] = NULL;
                mutex_unlock(&register_mutex);
                snd_card_free_when_closed(card);
        } else {
                mutex_unlock(&register_mutex);
        }
}

/* lock the shutdown (disconnect) task and autoresume */
int snd_usb_lock_shutdown(struct snd_usb_audio *chip)
{
        int err;

        atomic_inc(&chip->usage_count);
        if (atomic_read(&chip->shutdown)) {
                err = -EIO;
                goto error;
        }
        err = snd_usb_autoresume(chip);
        if (err < 0)
                goto error;
        return 0;

 error:
        if (atomic_dec_and_test(&chip->usage_count))
                wake_up(&chip->shutdown_wait);
        return err;
}

/* autosuspend and unlock the shutdown */
void snd_usb_unlock_shutdown(struct snd_usb_audio *chip)
{
        snd_usb_autosuspend(chip);
        if (atomic_dec_and_test(&chip->usage_count))
                wake_up(&chip->shutdown_wait);
}

#ifdef CONFIG_PM

int snd_usb_autoresume(struct snd_usb_audio *chip)
{
        int i, err;

        if (atomic_read(&chip->shutdown))
                return -EIO;
        if (atomic_inc_return(&chip->active) != 1)
                return 0;

        for (i = 0; i < chip->num_interfaces; i++) {
                err = usb_autopm_get_interface(chip->intf[i]);
                if (err < 0) {
                        /* rollback */
                        while (--i >= 0)
                                usb_autopm_put_interface(chip->intf[i]);
                        atomic_dec(&chip->active);
                        return err;
                }
        }
        return 0;
}

void snd_usb_autosuspend(struct snd_usb_audio *chip)
{
        int i;

        if (atomic_read(&chip->shutdown))
                return;
        if (!atomic_dec_and_test(&chip->active))
                return;

        for (i = 0; i < chip->num_interfaces; i++)
                usb_autopm_put_interface(chip->intf[i]);
}

static int usb_audio_suspend(struct usb_interface *intf, pm_message_t message)
{
        struct snd_usb_audio *chip = usb_get_intfdata(intf);
        struct snd_usb_stream *as;
        struct usb_mixer_interface *mixer;
        struct list_head *p;

        if (chip == (void *)-1L)
                return 0;

        if (!chip->num_suspended_intf++) {
                list_for_each_entry(as, &chip->pcm_list, list) {
                        snd_usb_pcm_suspend(as);
                        as->substream[0].need_setup_ep =
                                as->substream[1].need_setup_ep = true;
                }
                list_for_each(p, &chip->midi_list)
                        snd_usbmidi_suspend(p);
                list_for_each_entry(mixer, &chip->mixer_list, list)
                        snd_usb_mixer_suspend(mixer);
        }

        if (!PMSG_IS_AUTO(message) && !chip->system_suspend) {
                snd_power_change_state(chip->card, SNDRV_CTL_POWER_D3hot);
                chip->system_suspend = chip->num_suspended_intf;
        }

        return 0;
}

static int __usb_audio_resume(struct usb_interface *intf, bool reset_resume)
{
        struct snd_usb_audio *chip = usb_get_intfdata(intf);
        struct snd_usb_stream *as;
        struct usb_mixer_interface *mixer;
        struct list_head *p;
        int err = 0;

        if (chip == (void *)-1L)
                return 0;

        atomic_inc(&chip->active); /* avoid autopm */
        if (chip->num_suspended_intf > 1)
                goto out;

        list_for_each_entry(as, &chip->pcm_list, list) {
                err = snd_usb_pcm_resume(as);
                if (err < 0)
                        goto err_out;
        }

        /*
         * ALSA leaves material resumption to user space
         * we just notify and restart the mixers
         */
        list_for_each_entry(mixer, &chip->mixer_list, list) {
                err = snd_usb_mixer_resume(mixer, reset_resume);
                if (err < 0)
                        goto err_out;
        }

        list_for_each(p, &chip->midi_list) {
                snd_usbmidi_resume(p);
        }

 out:
        if (chip->num_suspended_intf == chip->system_suspend) {
                snd_power_change_state(chip->card, SNDRV_CTL_POWER_D0);
                chip->system_suspend = 0;
        }
        chip->num_suspended_intf--;

err_out:
        atomic_dec(&chip->active); /* allow autopm after this point */
        return err;
}

static int usb_audio_resume(struct usb_interface *intf)
{
        return __usb_audio_resume(intf, false);
}

static int usb_audio_reset_resume(struct usb_interface *intf)
{
        return __usb_audio_resume(intf, true);
}
#else
#define usb_audio_suspend       NULL
#define usb_audio_resume        NULL
#define usb_audio_reset_resume  NULL
#endif          /* CONFIG_PM */

static const struct usb_device_id usb_audio_ids [] = {
#include "quirks-table.h"
    { .match_flags = (USB_DEVICE_ID_MATCH_INT_CLASS | USB_DEVICE_ID_MATCH_INT_SUBCLASS),
      .bInterfaceClass = USB_CLASS_AUDIO,
      .bInterfaceSubClass = USB_SUBCLASS_AUDIOCONTROL },
    { }                                         /* Terminating entry */
};
MODULE_DEVICE_TABLE(usb, usb_audio_ids);

/*
 * entry point for linux usb interface
 */

static struct usb_driver usb_audio_driver = {
        .name =         "snd-usb-audio",
        .probe =        usb_audio_probe,
        .disconnect =   usb_audio_disconnect,
        .suspend =      usb_audio_suspend,
        .resume =       usb_audio_resume,
        .reset_resume = usb_audio_reset_resume,
        .id_table =     usb_audio_ids,
        .supports_autosuspend = 1,
};

module_usb_driver(usb_audio_driver);