ua101.c

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/*
 * Edirol UA-101/UA-1000 driver
 * Copyright (c) Clemens Ladisch <[email protected]>
 *
 * This driver is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License, version 2.
 *
 * This driver 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 driver.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <linux/init.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/usb.h>
#include <linux/usb/audio.h>
#include <sound/core.h>
#include <sound/initval.h>
#include <sound/pcm.h>
#include <sound/pcm_params.h>
#include "../usbaudio.h"
#include "../midi.h"

MODULE_DESCRIPTION("Edirol UA-101/1000 driver");
MODULE_AUTHOR("Clemens Ladisch <[email protected]>");
MODULE_LICENSE("GPL v2");
MODULE_SUPPORTED_DEVICE("{{Edirol,UA-101},{Edirol,UA-1000}}");

/*
 * Should not be lower than the minimum scheduling delay of the host
 * controller.  Some Intel controllers need more than one frame; as long as
 * that driver doesn't tell us about this, use 1.5 frames just to be sure.
 */
#define MIN_QUEUE_LENGTH    12
/* Somewhat random. */
#define MAX_QUEUE_LENGTH    30
/*
 * This magic value optimizes memory usage efficiency for the UA-101's packet
 * sizes at all sample rates, taking into account the stupid cache pool sizes
 * that usb_alloc_coherent() uses.
 */
#define DEFAULT_QUEUE_LENGTH    21

#define MAX_PACKET_SIZE     672 /* hardware specific */
#define MAX_MEMORY_BUFFERS  DIV_ROUND_UP(MAX_QUEUE_LENGTH, \
                         PAGE_SIZE / MAX_PACKET_SIZE)

static int index[SNDRV_CARDS] = SNDRV_DEFAULT_IDX;
static char *id[SNDRV_CARDS] = SNDRV_DEFAULT_STR;
static bool enable[SNDRV_CARDS] = SNDRV_DEFAULT_ENABLE_PNP;
static unsigned int queue_length = 21;

module_param_array(index, int, NULL, 0444);
MODULE_PARM_DESC(index, "card index");
module_param_array(id, charp, NULL, 0444);
MODULE_PARM_DESC(id, "ID string");
module_param_array(enable, bool, NULL, 0444);
MODULE_PARM_DESC(enable, "enable card");
module_param(queue_length, uint, 0644);
MODULE_PARM_DESC(queue_length, "USB queue length in microframes, "
         __stringify(MIN_QUEUE_LENGTH)"-"__stringify(MAX_QUEUE_LENGTH));

enum {
    INTF_PLAYBACK,
    INTF_CAPTURE,
    INTF_MIDI,

    INTF_COUNT
};

/* bits in struct ua101::states */
enum {
    USB_CAPTURE_RUNNING,
    USB_PLAYBACK_RUNNING,
    ALSA_CAPTURE_OPEN,
    ALSA_PLAYBACK_OPEN,
    ALSA_CAPTURE_RUNNING,
    ALSA_PLAYBACK_RUNNING,
    CAPTURE_URB_COMPLETED,
    PLAYBACK_URB_COMPLETED,
    DISCONNECTED,
};

struct ua101 {
    struct usb_device *dev;
    struct snd_card *card;
    struct usb_interface *intf[INTF_COUNT];
    int card_index;
    struct snd_pcm *pcm;
    struct list_head midi_list;
    u64 format_bit;
    unsigned int rate;
    unsigned int packets_per_second;
    spinlock_t lock;
    struct mutex mutex;
    unsigned long states;

    /* FIFO to synchronize playback rate to capture rate */
    unsigned int rate_feedback_start;
    unsigned int rate_feedback_count;
    u8 rate_feedback[MAX_QUEUE_LENGTH];

    struct list_head ready_playback_urbs;
    struct tasklet_struct playback_tasklet;
    wait_queue_head_t alsa_capture_wait;
    wait_queue_head_t rate_feedback_wait;
    wait_queue_head_t alsa_playback_wait;
    struct ua101_stream {
        struct snd_pcm_substream *substream;
        unsigned int usb_pipe;
        unsigned int channels;
        unsigned int frame_bytes;
        unsigned int max_packet_bytes;
        unsigned int period_pos;
        unsigned int buffer_pos;
        unsigned int queue_length;
        struct ua101_urb {
            struct urb urb;
            struct usb_iso_packet_descriptor iso_frame_desc[1];
            struct list_head ready_list;
        } *urbs[MAX_QUEUE_LENGTH];
        struct {
            unsigned int size;
            void *addr;
            dma_addr_t dma;
        } buffers[MAX_MEMORY_BUFFERS];
    } capture, playback;
};

static DEFINE_MUTEX(devices_mutex);
static unsigned int devices_used;
static struct usb_driver ua101_driver;

static void abort_alsa_playback(struct ua101 *ua);
static void abort_alsa_capture(struct ua101 *ua);

static const char *usb_error_string(int err)
{
    switch (err) {
    case -ENODEV:
        return "no device";
    case -ENOENT:
        return "endpoint not enabled";
    case -EPIPE:
        return "endpoint stalled";
    case -ENOSPC:
        return "not enough bandwidth";
    case -ESHUTDOWN:
        return "device disabled";
    case -EHOSTUNREACH:
        return "device suspended";
    case -EINVAL:
    case -EAGAIN:
    case -EFBIG:
    case -EMSGSIZE:
        return "internal error";
    default:
        return "unknown error";
    }
}

static void abort_usb_capture(struct ua101 *ua)
{
    if (test_and_clear_bit(USB_CAPTURE_RUNNING, &ua->states)) {
        wake_up(&ua->alsa_capture_wait);
        wake_up(&ua->rate_feedback_wait);
    }
}

static void abort_usb_playback(struct ua101 *ua)
{
    if (test_and_clear_bit(USB_PLAYBACK_RUNNING, &ua->states))
        wake_up(&ua->alsa_playback_wait);
}

static void playback_urb_complete(struct urb *usb_urb)
{
    struct ua101_urb *urb = (struct ua101_urb *)usb_urb;
    struct ua101 *ua = urb->urb.context;
    unsigned long flags;

    if (unlikely(urb->urb.status == -ENOENT ||  /* unlinked */
             urb->urb.status == -ENODEV ||  /* device removed */
             urb->urb.status == -ECONNRESET ||  /* unlinked */
             urb->urb.status == -ESHUTDOWN)) {  /* device disabled */
        abort_usb_playback(ua);
        abort_alsa_playback(ua);
        return;
    }

    if (test_bit(USB_PLAYBACK_RUNNING, &ua->states)) {
        /* append URB to FIFO */
        spin_lock_irqsave(&ua->lock, flags);
        list_add_tail(&urb->ready_list, &ua->ready_playback_urbs);
        if (ua->rate_feedback_count > 0)
            tasklet_schedule(&ua->playback_tasklet);
        ua->playback.substream->runtime->delay -=
                urb->urb.iso_frame_desc[0].length /
                        ua->playback.frame_bytes;
        spin_unlock_irqrestore(&ua->lock, flags);
    }
}

static void first_playback_urb_complete(struct urb *urb)
{
    struct ua101 *ua = urb->context;

    urb->complete = playback_urb_complete;
    playback_urb_complete(urb);

    set_bit(PLAYBACK_URB_COMPLETED, &ua->states);
    wake_up(&ua->alsa_playback_wait);
}

/* copy data from the ALSA ring buffer into the URB buffer */
static bool copy_playback_data(struct ua101_stream *stream, struct urb *urb,
                   unsigned int frames)
{
    struct snd_pcm_runtime *runtime;
    unsigned int frame_bytes, frames1;
    const u8 *source;

    runtime = stream->substream->runtime;
    frame_bytes = stream->frame_bytes;
    source = runtime->dma_area + stream->buffer_pos * frame_bytes;
    if (stream->buffer_pos + frames <= runtime->buffer_size) {
        memcpy(urb->transfer_buffer, source, frames * frame_bytes);
    } else {
        /* wrap around at end of ring buffer */
        frames1 = runtime->buffer_size - stream->buffer_pos;
        memcpy(urb->transfer_buffer, source, frames1 * frame_bytes);
        memcpy(urb->transfer_buffer + frames1 * frame_bytes,
               runtime->dma_area, (frames - frames1) * frame_bytes);
    }

    stream->buffer_pos += frames;
    if (stream->buffer_pos >= runtime->buffer_size)
        stream->buffer_pos -= runtime->buffer_size;
    stream->period_pos += frames;
    if (stream->period_pos >= runtime->period_size) {
        stream->period_pos -= runtime->period_size;
        return true;
    }
    return false;
}

static inline void add_with_wraparound(struct ua101 *ua,
                       unsigned int *value, unsigned int add)
{
    *value += add;
    if (*value >= ua->playback.queue_length)
        *value -= ua->playback.queue_length;
}

static void playback_tasklet(unsigned long data)
{
    struct ua101 *ua = (void *)data;
    unsigned long flags;
    unsigned int frames;
    struct ua101_urb *urb;
    bool do_period_elapsed = false;
    int err;

    if (unlikely(!test_bit(USB_PLAYBACK_RUNNING, &ua->states)))
        return;

    /*
     * Synchronizing the playback rate to the capture rate is done by using
     * the same sequence of packet sizes for both streams.
     * Submitting a playback URB therefore requires both a ready URB and
     * the size of the corresponding capture packet, i.e., both playback
     * and capture URBs must have been completed.  Since the USB core does
     * not guarantee that playback and capture complete callbacks are
     * called alternately, we use two FIFOs for packet sizes and read URBs;
     * submitting playback URBs is possible as long as both FIFOs are
     * nonempty.
     */
    spin_lock_irqsave(&ua->lock, flags);
    while (ua->rate_feedback_count > 0 &&
           !list_empty(&ua->ready_playback_urbs)) {
        /* take packet size out of FIFO */
        frames = ua->rate_feedback[ua->rate_feedback_start];
        add_with_wraparound(ua, &ua->rate_feedback_start, 1);
        ua->rate_feedback_count--;

        /* take URB out of FIFO */
        urb = list_first_entry(&ua->ready_playback_urbs,
                       struct ua101_urb, ready_list);
        list_del(&urb->ready_list);

        /* fill packet with data or silence */
        urb->urb.iso_frame_desc[0].length =
            frames * ua->playback.frame_bytes;
        if (test_bit(ALSA_PLAYBACK_RUNNING, &ua->states))
            do_period_elapsed |= copy_playback_data(&ua->playback,
                                &urb->urb,
                                frames);
        else
            memset(urb->urb.transfer_buffer, 0,
                   urb->urb.iso_frame_desc[0].length);

        /* and off you go ... */
        err = usb_submit_urb(&urb->urb, GFP_ATOMIC);
        if (unlikely(err < 0)) {
            spin_unlock_irqrestore(&ua->lock, flags);
            abort_usb_playback(ua);
            abort_alsa_playback(ua);
            dev_err(&ua->dev->dev, "USB request error %d: %s\n",
                err, usb_error_string(err));
            return;
        }
        ua->playback.substream->runtime->delay += frames;
    }
    spin_unlock_irqrestore(&ua->lock, flags);
    if (do_period_elapsed)
        snd_pcm_period_elapsed(ua->playback.substream);
}

/* copy data from the URB buffer into the ALSA ring buffer */
static bool copy_capture_data(struct ua101_stream *stream, struct urb *urb,
                  unsigned int frames)
{
    struct snd_pcm_runtime *runtime;
    unsigned int frame_bytes, frames1;
    u8 *dest;

    runtime = stream->substream->runtime;
    frame_bytes = stream->frame_bytes;
    dest = runtime->dma_area + stream->buffer_pos * frame_bytes;
    if (stream->buffer_pos + frames <= runtime->buffer_size) {
        memcpy(dest, urb->transfer_buffer, frames * frame_bytes);
    } else {
        /* wrap around at end of ring buffer */
        frames1 = runtime->buffer_size - stream->buffer_pos;
        memcpy(dest, urb->transfer_buffer, frames1 * frame_bytes);
        memcpy(runtime->dma_area,
               urb->transfer_buffer + frames1 * frame_bytes,
               (frames - frames1) * frame_bytes);
    }

    stream->buffer_pos += frames;
    if (stream->buffer_pos >= runtime->buffer_size)
        stream->buffer_pos -= runtime->buffer_size;
    stream->period_pos += frames;
    if (stream->period_pos >= runtime->period_size) {
        stream->period_pos -= runtime->period_size;
        return true;
    }
    return false;
}

static void capture_urb_complete(struct urb *urb)
{
    struct ua101 *ua = urb->context;
    struct ua101_stream *stream = &ua->capture;
    unsigned long flags;
    unsigned int frames, write_ptr;
    bool do_period_elapsed;
    int err;

    if (unlikely(urb->status == -ENOENT ||      /* unlinked */
             urb->status == -ENODEV ||      /* device removed */
             urb->status == -ECONNRESET ||  /* unlinked */
             urb->status == -ESHUTDOWN))    /* device disabled */
        goto stream_stopped;

    if (urb->status >= 0 && urb->iso_frame_desc[0].status >= 0)
        frames = urb->iso_frame_desc[0].actual_length /
            stream->frame_bytes;
    else
        frames = 0;

    spin_lock_irqsave(&ua->lock, flags);

    if (frames > 0 && test_bit(ALSA_CAPTURE_RUNNING, &ua->states))
        do_period_elapsed = copy_capture_data(stream, urb, frames);
    else
        do_period_elapsed = false;

    if (test_bit(USB_CAPTURE_RUNNING, &ua->states)) {
        err = usb_submit_urb(urb, GFP_ATOMIC);
        if (unlikely(err < 0)) {
            spin_unlock_irqrestore(&ua->lock, flags);
            dev_err(&ua->dev->dev, "USB request error %d: %s\n",
                err, usb_error_string(err));
            goto stream_stopped;
        }

        /* append packet size to FIFO */
        write_ptr = ua->rate_feedback_start;
        add_with_wraparound(ua, &write_ptr, ua->rate_feedback_count);
        ua->rate_feedback[write_ptr] = frames;
        if (ua->rate_feedback_count < ua->playback.queue_length) {
            ua->rate_feedback_count++;
            if (ua->rate_feedback_count ==
                        ua->playback.queue_length)
                wake_up(&ua->rate_feedback_wait);
        } else {
            /*
             * Ring buffer overflow; this happens when the playback
             * stream is not running.  Throw away the oldest entry,
             * so that the playback stream, when it starts, sees
             * the most recent packet sizes.
             */
            add_with_wraparound(ua, &ua->rate_feedback_start, 1);
        }
        if (test_bit(USB_PLAYBACK_RUNNING, &ua->states) &&
            !list_empty(&ua->ready_playback_urbs))
            tasklet_schedule(&ua->playback_tasklet);
    }

    spin_unlock_irqrestore(&ua->lock, flags);

    if (do_period_elapsed)
        snd_pcm_period_elapsed(stream->substream);

    return;

stream_stopped:
    abort_usb_playback(ua);
    abort_usb_capture(ua);
    abort_alsa_playback(ua);
    abort_alsa_capture(ua);
}

static void first_capture_urb_complete(struct urb *urb)
{
    struct ua101 *ua = urb->context;

    urb->complete = capture_urb_complete;
    capture_urb_complete(urb);

    set_bit(CAPTURE_URB_COMPLETED, &ua->states);
    wake_up(&ua->alsa_capture_wait);
}

static int submit_stream_urbs(struct ua101 *ua, struct ua101_stream *stream)
{
    unsigned int i;

    for (i = 0; i < stream->queue_length; ++i) {
        int err = usb_submit_urb(&stream->urbs[i]->urb, GFP_KERNEL);
        if (err < 0) {
            dev_err(&ua->dev->dev, "USB request error %d: %s\n",
                err, usb_error_string(err));
            return err;
        }
    }
    return 0;
}

static void kill_stream_urbs(struct ua101_stream *stream)
{
    unsigned int i;

    for (i = 0; i < stream->queue_length; ++i)
        if (stream->urbs[i])
            usb_kill_urb(&stream->urbs[i]->urb);
}

static int enable_iso_interface(struct ua101 *ua, unsigned int intf_index)
{
    struct usb_host_interface *alts;

    alts = ua->intf[intf_index]->cur_altsetting;
    if (alts->desc.bAlternateSetting != 1) {
        int err = usb_set_interface(ua->dev,
                        alts->desc.bInterfaceNumber, 1);
        if (err < 0) {
            dev_err(&ua->dev->dev,
                "cannot initialize interface; error %d: %s\n",
                err, usb_error_string(err));
            return err;
        }
    }
    return 0;
}

static void disable_iso_interface(struct ua101 *ua, unsigned int intf_index)
{
    struct usb_host_interface *alts;

    if (!ua->intf[intf_index])
        return;

    alts = ua->intf[intf_index]->cur_altsetting;
    if (alts->desc.bAlternateSetting != 0) {
        int err = usb_set_interface(ua->dev,
                        alts->desc.bInterfaceNumber, 0);
        if (err < 0 && !test_bit(DISCONNECTED, &ua->states))
            dev_warn(&ua->dev->dev,
                 "interface reset failed; error %d: %s\n",
                 err, usb_error_string(err));
    }
}

static void stop_usb_capture(struct ua101 *ua)
{
    clear_bit(USB_CAPTURE_RUNNING, &ua->states);

    kill_stream_urbs(&ua->capture);

    disable_iso_interface(ua, INTF_CAPTURE);
}

static int start_usb_capture(struct ua101 *ua)
{
    int err;

    if (test_bit(DISCONNECTED, &ua->states))
        return -ENODEV;

    if (test_bit(USB_CAPTURE_RUNNING, &ua->states))
        return 0;

    kill_stream_urbs(&ua->capture);

    err = enable_iso_interface(ua, INTF_CAPTURE);
    if (err < 0)
        return err;

    clear_bit(CAPTURE_URB_COMPLETED, &ua->states);
    ua->capture.urbs[0]->urb.complete = first_capture_urb_complete;
    ua->rate_feedback_start = 0;
    ua->rate_feedback_count = 0;

    set_bit(USB_CAPTURE_RUNNING, &ua->states);
    err = submit_stream_urbs(ua, &ua->capture);
    if (err < 0)
        stop_usb_capture(ua);
    return err;
}

static void stop_usb_playback(struct ua101 *ua)
{
    clear_bit(USB_PLAYBACK_RUNNING, &ua->states);

    kill_stream_urbs(&ua->playback);

    tasklet_kill(&ua->playback_tasklet);

    disable_iso_interface(ua, INTF_PLAYBACK);
}

static int start_usb_playback(struct ua101 *ua)
{
    unsigned int i, frames;
    struct urb *urb;
    int err = 0;

    if (test_bit(DISCONNECTED, &ua->states))
        return -ENODEV;

    if (test_bit(USB_PLAYBACK_RUNNING, &ua->states))
        return 0;

    kill_stream_urbs(&ua->playback);
    tasklet_kill(&ua->playback_tasklet);

    err = enable_iso_interface(ua, INTF_PLAYBACK);
    if (err < 0)
        return err;

    clear_bit(PLAYBACK_URB_COMPLETED, &ua->states);
    ua->playback.urbs[0]->urb.complete =
        first_playback_urb_complete;
    spin_lock_irq(&ua->lock);
    INIT_LIST_HEAD(&ua->ready_playback_urbs);
    spin_unlock_irq(&ua->lock);

    /*
     * We submit the initial URBs all at once, so we have to wait for the
     * packet size FIFO to be full.
     */
    wait_event(ua->rate_feedback_wait,
           ua->rate_feedback_count >= ua->playback.queue_length ||
           !test_bit(USB_CAPTURE_RUNNING, &ua->states) ||
           test_bit(DISCONNECTED, &ua->states));
    if (test_bit(DISCONNECTED, &ua->states)) {
        stop_usb_playback(ua);
        return -ENODEV;
    }
    if (!test_bit(USB_CAPTURE_RUNNING, &ua->states)) {
        stop_usb_playback(ua);
        return -EIO;
    }

    for (i = 0; i < ua->playback.queue_length; ++i) {
        /* all initial URBs contain silence */
        spin_lock_irq(&ua->lock);
        frames = ua->rate_feedback[ua->rate_feedback_start];
        add_with_wraparound(ua, &ua->rate_feedback_start, 1);
        ua->rate_feedback_count--;
        spin_unlock_irq(&ua->lock);
        urb = &ua->playback.urbs[i]->urb;
        urb->iso_frame_desc[0].length =
            frames * ua->playback.frame_bytes;
        memset(urb->transfer_buffer, 0,
               urb->iso_frame_desc[0].length);
    }

    set_bit(USB_PLAYBACK_RUNNING, &ua->states);
    err = submit_stream_urbs(ua, &ua->playback);
    if (err < 0)
        stop_usb_playback(ua);
    return err;
}

static void abort_alsa_capture(struct ua101 *ua)
{
    if (test_bit(ALSA_CAPTURE_RUNNING, &ua->states))
        snd_pcm_stop(ua->capture.substream, SNDRV_PCM_STATE_XRUN);
}

static void abort_alsa_playback(struct ua101 *ua)
{
    if (test_bit(ALSA_PLAYBACK_RUNNING, &ua->states))
        snd_pcm_stop(ua->playback.substream, SNDRV_PCM_STATE_XRUN);
}

static int set_stream_hw(struct ua101 *ua, struct snd_pcm_substream *substream,
             unsigned int channels)
{
    int err;

    substream->runtime->hw.info =
        SNDRV_PCM_INFO_MMAP |
        SNDRV_PCM_INFO_MMAP_VALID |
        SNDRV_PCM_INFO_BATCH |
        SNDRV_PCM_INFO_INTERLEAVED |
        SNDRV_PCM_INFO_BLOCK_TRANSFER |
        SNDRV_PCM_INFO_FIFO_IN_FRAMES;
    substream->runtime->hw.formats = ua->format_bit;
    substream->runtime->hw.rates = snd_pcm_rate_to_rate_bit(ua->rate);
    substream->runtime->hw.rate_min = ua->rate;
    substream->runtime->hw.rate_max = ua->rate;
    substream->runtime->hw.channels_min = channels;
    substream->runtime->hw.channels_max = channels;
    substream->runtime->hw.buffer_bytes_max = 45000 * 1024;
    substream->runtime->hw.period_bytes_min = 1;
    substream->runtime->hw.period_bytes_max = UINT_MAX;
    substream->runtime->hw.periods_min = 2;
    substream->runtime->hw.periods_max = UINT_MAX;
    err = snd_pcm_hw_constraint_minmax(substream->runtime,
                       SNDRV_PCM_HW_PARAM_PERIOD_TIME,
                       1500000 / ua->packets_per_second,
                       UINT_MAX);
    if (err < 0)
        return err;
    err = snd_pcm_hw_constraint_msbits(substream->runtime, 0, 32, 24);
    return err;
}

static int capture_pcm_open(struct snd_pcm_substream *substream)
{
    struct ua101 *ua = substream->private_data;
    int err;

    ua->capture.substream = substream;
    err = set_stream_hw(ua, substream, ua->capture.channels);
    if (err < 0)
        return err;
    substream->runtime->hw.fifo_size =
        DIV_ROUND_CLOSEST(ua->rate, ua->packets_per_second);
    substream->runtime->delay = substream->runtime->hw.fifo_size;

    mutex_lock(&ua->mutex);
    err = start_usb_capture(ua);
    if (err >= 0)
        set_bit(ALSA_CAPTURE_OPEN, &ua->states);
    mutex_unlock(&ua->mutex);
    return err;
}

static int playback_pcm_open(struct snd_pcm_substream *substream)
{
    struct ua101 *ua = substream->private_data;
    int err;

    ua->playback.substream = substream;
    err = set_stream_hw(ua, substream, ua->playback.channels);
    if (err < 0)
        return err;
    substream->runtime->hw.fifo_size =
        DIV_ROUND_CLOSEST(ua->rate * ua->playback.queue_length,
                  ua->packets_per_second);

    mutex_lock(&ua->mutex);
    err = start_usb_capture(ua);
    if (err < 0)
        goto error;
    err = start_usb_playback(ua);
    if (err < 0) {
        if (!test_bit(ALSA_CAPTURE_OPEN, &ua->states))
            stop_usb_capture(ua);
        goto error;
    }
    set_bit(ALSA_PLAYBACK_OPEN, &ua->states);
error:
    mutex_unlock(&ua->mutex);
    return err;
}

static int capture_pcm_close(struct snd_pcm_substream *substream)
{
    struct ua101 *ua = substream->private_data;

    mutex_lock(&ua->mutex);
    clear_bit(ALSA_CAPTURE_OPEN, &ua->states);
    if (!test_bit(ALSA_PLAYBACK_OPEN, &ua->states))
        stop_usb_capture(ua);
    mutex_unlock(&ua->mutex);
    return 0;
}

static int playback_pcm_close(struct snd_pcm_substream *substream)
{
    struct ua101 *ua = substream->private_data;

    mutex_lock(&ua->mutex);
    stop_usb_playback(ua);
    clear_bit(ALSA_PLAYBACK_OPEN, &ua->states);
    if (!test_bit(ALSA_CAPTURE_OPEN, &ua->states))
        stop_usb_capture(ua);
    mutex_unlock(&ua->mutex);
    return 0;
}

static int capture_pcm_hw_params(struct snd_pcm_substream *substream,
                 struct snd_pcm_hw_params *hw_params)
{
    struct ua101 *ua = substream->private_data;
    int err;

    mutex_lock(&ua->mutex);
    err = start_usb_capture(ua);
    mutex_unlock(&ua->mutex);
    if (err < 0)
        return err;

    return snd_pcm_lib_alloc_vmalloc_buffer(substream,
                        params_buffer_bytes(hw_params));
}

static int playback_pcm_hw_params(struct snd_pcm_substream *substream,
                  struct snd_pcm_hw_params *hw_params)
{
    struct ua101 *ua = substream->private_data;
    int err;

    mutex_lock(&ua->mutex);
    err = start_usb_capture(ua);
    if (err >= 0)
        err = start_usb_playback(ua);
    mutex_unlock(&ua->mutex);
    if (err < 0)
        return err;

    return snd_pcm_lib_alloc_vmalloc_buffer(substream,
                        params_buffer_bytes(hw_params));
}

static int ua101_pcm_hw_free(struct snd_pcm_substream *substream)
{
    return snd_pcm_lib_free_vmalloc_buffer(substream);
}

static int capture_pcm_prepare(struct snd_pcm_substream *substream)
{
    struct ua101 *ua = substream->private_data;
    int err;

    mutex_lock(&ua->mutex);
    err = start_usb_capture(ua);
    mutex_unlock(&ua->mutex);
    if (err < 0)
        return err;

    /*
     * The EHCI driver schedules the first packet of an iso stream at 10 ms
     * in the future, i.e., no data is actually captured for that long.
     * Take the wait here so that the stream is known to be actually
     * running when the start trigger has been called.
     */
    wait_event(ua->alsa_capture_wait,
           test_bit(CAPTURE_URB_COMPLETED, &ua->states) ||
           !test_bit(USB_CAPTURE_RUNNING, &ua->states));
    if (test_bit(DISCONNECTED, &ua->states))
        return -ENODEV;
    if (!test_bit(USB_CAPTURE_RUNNING, &ua->states))
        return -EIO;

    ua->capture.period_pos = 0;
    ua->capture.buffer_pos = 0;
    return 0;
}

static int playback_pcm_prepare(struct snd_pcm_substream *substream)
{
    struct ua101 *ua = substream->private_data;
    int err;

    mutex_lock(&ua->mutex);
    err = start_usb_capture(ua);
    if (err >= 0)
        err = start_usb_playback(ua);
    mutex_unlock(&ua->mutex);
    if (err < 0)
        return err;

    /* see the comment in capture_pcm_prepare() */
    wait_event(ua->alsa_playback_wait,
           test_bit(PLAYBACK_URB_COMPLETED, &ua->states) ||
           !test_bit(USB_PLAYBACK_RUNNING, &ua->states));
    if (test_bit(DISCONNECTED, &ua->states))
        return -ENODEV;
    if (!test_bit(USB_PLAYBACK_RUNNING, &ua->states))
        return -EIO;

    substream->runtime->delay = 0;
    ua->playback.period_pos = 0;
    ua->playback.buffer_pos = 0;
    return 0;
}

static int capture_pcm_trigger(struct snd_pcm_substream *substream, int cmd)
{
    struct ua101 *ua = substream->private_data;

    switch (cmd) {
    case SNDRV_PCM_TRIGGER_START:
        if (!test_bit(USB_CAPTURE_RUNNING, &ua->states))
            return -EIO;
        set_bit(ALSA_CAPTURE_RUNNING, &ua->states);
        return 0;
    case SNDRV_PCM_TRIGGER_STOP:
        clear_bit(ALSA_CAPTURE_RUNNING, &ua->states);
        return 0;
    default:
        return -EINVAL;
    }
}

static int playback_pcm_trigger(struct snd_pcm_substream *substream, int cmd)
{
    struct ua101 *ua = substream->private_data;

    switch (cmd) {
    case SNDRV_PCM_TRIGGER_START:
        if (!test_bit(USB_PLAYBACK_RUNNING, &ua->states))
            return -EIO;
        set_bit(ALSA_PLAYBACK_RUNNING, &ua->states);
        return 0;
    case SNDRV_PCM_TRIGGER_STOP:
        clear_bit(ALSA_PLAYBACK_RUNNING, &ua->states);
        return 0;
    default:
        return -EINVAL;
    }
}

static inline snd_pcm_uframes_t ua101_pcm_pointer(struct ua101 *ua,
                          struct ua101_stream *stream)
{
    unsigned long flags;
    unsigned int pos;

    spin_lock_irqsave(&ua->lock, flags);
    pos = stream->buffer_pos;
    spin_unlock_irqrestore(&ua->lock, flags);
    return pos;
}

static snd_pcm_uframes_t capture_pcm_pointer(struct snd_pcm_substream *subs)
{
    struct ua101 *ua = subs->private_data;

    return ua101_pcm_pointer(ua, &ua->capture);
}

static snd_pcm_uframes_t playback_pcm_pointer(struct snd_pcm_substream *subs)
{
    struct ua101 *ua = subs->private_data;

    return ua101_pcm_pointer(ua, &ua->playback);
}

static struct snd_pcm_ops capture_pcm_ops = {
    .open = capture_pcm_open,
    .close = capture_pcm_close,
    .ioctl = snd_pcm_lib_ioctl,
    .hw_params = capture_pcm_hw_params,
    .hw_free = ua101_pcm_hw_free,
    .prepare = capture_pcm_prepare,
    .trigger = capture_pcm_trigger,
    .pointer = capture_pcm_pointer,
    .page = snd_pcm_lib_get_vmalloc_page,
    .mmap = snd_pcm_lib_mmap_vmalloc,
};

static struct snd_pcm_ops playback_pcm_ops = {
    .open = playback_pcm_open,
    .close = playback_pcm_close,
    .ioctl = snd_pcm_lib_ioctl,
    .hw_params = playback_pcm_hw_params,
    .hw_free = ua101_pcm_hw_free,
    .prepare = playback_pcm_prepare,
    .trigger = playback_pcm_trigger,
    .pointer = playback_pcm_pointer,
    .page = snd_pcm_lib_get_vmalloc_page,
    .mmap = snd_pcm_lib_mmap_vmalloc,
};

static const struct uac_format_type_i_discrete_descriptor *
find_format_descriptor(struct usb_interface *interface)
{
    struct usb_host_interface *alt;
    u8 *extra;
    int extralen;

    if (interface->num_altsetting != 2) {
        dev_err(&interface->dev, "invalid num_altsetting\n");
        return NULL;
    }

    alt = &interface->altsetting[0];
    if (alt->desc.bNumEndpoints != 0) {
        dev_err(&interface->dev, "invalid bNumEndpoints\n");
        return NULL;
    }

    alt = &interface->altsetting[1];
    if (alt->desc.bNumEndpoints != 1) {
        dev_err(&interface->dev, "invalid bNumEndpoints\n");
        return NULL;
    }

    extra = alt->extra;
    extralen = alt->extralen;
    while (extralen >= sizeof(struct usb_descriptor_header)) {
        struct uac_format_type_i_discrete_descriptor *desc;

        desc = (struct uac_format_type_i_discrete_descriptor *)extra;
        if (desc->bLength > extralen) {
            dev_err(&interface->dev, "descriptor overflow\n");
            return NULL;
        }
        if (desc->bLength == UAC_FORMAT_TYPE_I_DISCRETE_DESC_SIZE(1) &&
            desc->bDescriptorType == USB_DT_CS_INTERFACE &&
            desc->bDescriptorSubtype == UAC_FORMAT_TYPE) {
            if (desc->bFormatType != UAC_FORMAT_TYPE_I_PCM ||
                desc->bSamFreqType != 1) {
                dev_err(&interface->dev,
                    "invalid format type\n");
                return NULL;
            }
            return desc;
        }
        extralen -= desc->bLength;
        extra += desc->bLength;
    }
    dev_err(&interface->dev, "sample format descriptor not found\n");
    return NULL;
}

static int detect_usb_format(struct ua101 *ua)
{
    const struct uac_format_type_i_discrete_descriptor *fmt_capture;
    const struct uac_format_type_i_discrete_descriptor *fmt_playback;
    const struct usb_endpoint_descriptor *epd;
    unsigned int rate2;

    fmt_capture = find_format_descriptor(ua->intf[INTF_CAPTURE]);
    fmt_playback = find_format_descriptor(ua->intf[INTF_PLAYBACK]);
    if (!fmt_capture || !fmt_playback)
        return -ENXIO;

    switch (fmt_capture->bSubframeSize) {
    case 3:
        ua->format_bit = SNDRV_PCM_FMTBIT_S24_3LE;
        break;
    case 4:
        ua->format_bit = SNDRV_PCM_FMTBIT_S32_LE;
        break;
    default:
        dev_err(&ua->dev->dev, "sample width is not 24 or 32 bits\n");
        return -ENXIO;
    }
    if (fmt_capture->bSubframeSize != fmt_playback->bSubframeSize) {
        dev_err(&ua->dev->dev,
            "playback/capture sample widths do not match\n");
        return -ENXIO;
    }

    if (fmt_capture->bBitResolution != 24 ||
        fmt_playback->bBitResolution != 24) {
        dev_err(&ua->dev->dev, "sample width is not 24 bits\n");
        return -ENXIO;
    }

    ua->rate = combine_triple(fmt_capture->tSamFreq[0]);
    rate2 = combine_triple(fmt_playback->tSamFreq[0]);
    if (ua->rate != rate2) {
        dev_err(&ua->dev->dev,
            "playback/capture rates do not match: %u/%u\n",
            rate2, ua->rate);
        return -ENXIO;
    }

    switch (ua->dev->speed) {
    case USB_SPEED_FULL:
        ua->packets_per_second = 1000;
        break;
    case USB_SPEED_HIGH:
        ua->packets_per_second = 8000;
        break;
    default:
        dev_err(&ua->dev->dev, "unknown device speed\n");
        return -ENXIO;
    }

    ua->capture.channels = fmt_capture->bNrChannels;
    ua->playback.channels = fmt_playback->bNrChannels;
    ua->capture.frame_bytes =
        fmt_capture->bSubframeSize * ua->capture.channels;
    ua->playback.frame_bytes =
        fmt_playback->bSubframeSize * ua->playback.channels;

    epd = &ua->intf[INTF_CAPTURE]->altsetting[1].endpoint[0].desc;
    if (!usb_endpoint_is_isoc_in(epd)) {
        dev_err(&ua->dev->dev, "invalid capture endpoint\n");
        return -ENXIO;
    }
    ua->capture.usb_pipe = usb_rcvisocpipe(ua->dev, usb_endpoint_num(epd));
    ua->capture.max_packet_bytes = le16_to_cpu(epd->wMaxPacketSize);

    epd = &ua->intf[INTF_PLAYBACK]->altsetting[1].endpoint[0].desc;
    if (!usb_endpoint_is_isoc_out(epd)) {
        dev_err(&ua->dev->dev, "invalid playback endpoint\n");
        return -ENXIO;
    }
    ua->playback.usb_pipe = usb_sndisocpipe(ua->dev, usb_endpoint_num(epd));
    ua->playback.max_packet_bytes = le16_to_cpu(epd->wMaxPacketSize);
    return 0;
}

static int alloc_stream_buffers(struct ua101 *ua, struct ua101_stream *stream)
{
    unsigned int remaining_packets, packets, packets_per_page, i;
    size_t size;

    stream->queue_length = queue_length;
    stream->queue_length = max(stream->queue_length,
                   (unsigned int)MIN_QUEUE_LENGTH);
    stream->queue_length = min(stream->queue_length,
                   (unsigned int)MAX_QUEUE_LENGTH);

    /*
     * The cache pool sizes used by usb_alloc_coherent() (128, 512, 2048) are
     * quite bad when used with the packet sizes of this device (e.g. 280,
     * 520, 624).  Therefore, we allocate and subdivide entire pages, using
     * a smaller buffer only for the last chunk.
     */
    remaining_packets = stream->queue_length;
    packets_per_page = PAGE_SIZE / stream->max_packet_bytes;
    for (i = 0; i < ARRAY_SIZE(stream->buffers); ++i) {
        packets = min(remaining_packets, packets_per_page);
        size = packets * stream->max_packet_bytes;
        stream->buffers[i].addr =
            usb_alloc_coherent(ua->dev, size, GFP_KERNEL,
                       &stream->buffers[i].dma);
        if (!stream->buffers[i].addr)
            return -ENOMEM;
        stream->buffers[i].size = size;
        remaining_packets -= packets;
        if (!remaining_packets)
            break;
    }
    if (remaining_packets) {
        dev_err(&ua->dev->dev, "too many packets\n");
        return -ENXIO;
    }
    return 0;
}

static void free_stream_buffers(struct ua101 *ua, struct ua101_stream *stream)
{
    unsigned int i;

    for (i = 0; i < ARRAY_SIZE(stream->buffers); ++i)
        usb_free_coherent(ua->dev,
                  stream->buffers[i].size,
                  stream->buffers[i].addr,
                  stream->buffers[i].dma);
}

static int alloc_stream_urbs(struct ua101 *ua, struct ua101_stream *stream,
                 void (*urb_complete)(struct urb *))
{
    unsigned max_packet_size = stream->max_packet_bytes;
    struct ua101_urb *urb;
    unsigned int b, u = 0;

    for (b = 0; b < ARRAY_SIZE(stream->buffers); ++b) {
        unsigned int size = stream->buffers[b].size;
        u8 *addr = stream->buffers[b].addr;
        dma_addr_t dma = stream->buffers[b].dma;

        while (size >= max_packet_size) {
            if (u >= stream->queue_length)
                goto bufsize_error;
            urb = kmalloc(sizeof(*urb), GFP_KERNEL);
            if (!urb)
                return -ENOMEM;
            usb_init_urb(&urb->urb);
            urb->urb.dev = ua->dev;
            urb->urb.pipe = stream->usb_pipe;
            urb->urb.transfer_flags = URB_ISO_ASAP |
                    URB_NO_TRANSFER_DMA_MAP;
            urb->urb.transfer_buffer = addr;
            urb->urb.transfer_dma = dma;
            urb->urb.transfer_buffer_length = max_packet_size;
            urb->urb.number_of_packets = 1;
            urb->urb.interval = 1;
            urb->urb.context = ua;
            urb->urb.complete = urb_complete;
            urb->urb.iso_frame_desc[0].offset = 0;
            urb->urb.iso_frame_desc[0].length = max_packet_size;
            stream->urbs[u++] = urb;
            size -= max_packet_size;
            addr += max_packet_size;
            dma += max_packet_size;
        }
    }
    if (u == stream->queue_length)
        return 0;
bufsize_error:
    dev_err(&ua->dev->dev, "internal buffer size error\n");
    return -ENXIO;
}

static void free_stream_urbs(struct ua101_stream *stream)
{
    unsigned int i;

    for (i = 0; i < stream->queue_length; ++i) {
        kfree(stream->urbs[i]);
        stream->urbs[i] = NULL;
    }
}

static void free_usb_related_resources(struct ua101 *ua,
                       struct usb_interface *interface)
{
    unsigned int i;
    struct usb_interface *intf;

    mutex_lock(&ua->mutex);
    free_stream_urbs(&ua->capture);
    free_stream_urbs(&ua->playback);
    mutex_unlock(&ua->mutex);
    free_stream_buffers(ua, &ua->capture);
    free_stream_buffers(ua, &ua->playback);

    for (i = 0; i < ARRAY_SIZE(ua->intf); ++i) {
        mutex_lock(&ua->mutex);
        intf = ua->intf[i];
        ua->intf[i] = NULL;
        mutex_unlock(&ua->mutex);
        if (intf) {
            usb_set_intfdata(intf, NULL);
            if (intf != interface)
                usb_driver_release_interface(&ua101_driver,
                                 intf);
        }
    }
}

static void ua101_card_free(struct snd_card *card)
{
    struct ua101 *ua = card->private_data;

    mutex_destroy(&ua->mutex);
}

static int ua101_probe(struct usb_interface *interface,
               const struct usb_device_id *usb_id)
{
    static const struct snd_usb_midi_endpoint_info midi_ep = {
        .out_cables = 0x0001,
        .in_cables = 0x0001
    };
    static const struct snd_usb_audio_quirk midi_quirk = {
        .type = QUIRK_MIDI_FIXED_ENDPOINT,
        .data = &midi_ep
    };
    static const int intf_numbers[2][3] = {
        {   /* UA-101 */
            [INTF_PLAYBACK] = 0,
            [INTF_CAPTURE] = 1,
            [INTF_MIDI] = 2,
        },
        {   /* UA-1000 */
            [INTF_CAPTURE] = 1,
            [INTF_PLAYBACK] = 2,
            [INTF_MIDI] = 3,
        },
    };
    struct snd_card *card;
    struct ua101 *ua;
    unsigned int card_index, i;
    int is_ua1000;
    const char *name;
    char usb_path[32];
    int err;

    is_ua1000 = usb_id->idProduct == 0x0044;

    if (interface->altsetting->desc.bInterfaceNumber !=
        intf_numbers[is_ua1000][0])
        return -ENODEV;

    mutex_lock(&devices_mutex);

    for (card_index = 0; card_index < SNDRV_CARDS; ++card_index)
        if (enable[card_index] && !(devices_used & (1 << card_index)))
            break;
    if (card_index >= SNDRV_CARDS) {
        mutex_unlock(&devices_mutex);
        return -ENOENT;
    }
    err = snd_card_create(index[card_index], id[card_index], THIS_MODULE,
                  sizeof(*ua), &card);
    if (err < 0) {
        mutex_unlock(&devices_mutex);
        return err;
    }
    card->private_free = ua101_card_free;
    ua = card->private_data;
    ua->dev = interface_to_usbdev(interface);
    ua->card = card;
    ua->card_index = card_index;
    INIT_LIST_HEAD(&ua->midi_list);
    spin_lock_init(&ua->lock);
    mutex_init(&ua->mutex);
    INIT_LIST_HEAD(&ua->ready_playback_urbs);
    tasklet_init(&ua->playback_tasklet,
             playback_tasklet, (unsigned long)ua);
    init_waitqueue_head(&ua->alsa_capture_wait);
    init_waitqueue_head(&ua->rate_feedback_wait);
    init_waitqueue_head(&ua->alsa_playback_wait);

    ua->intf[0] = interface;
    for (i = 1; i < ARRAY_SIZE(ua->intf); ++i) {
        ua->intf[i] = usb_ifnum_to_if(ua->dev,
                          intf_numbers[is_ua1000][i]);
        if (!ua->intf[i]) {
            dev_err(&ua->dev->dev, "interface %u not found\n",
                intf_numbers[is_ua1000][i]);
            err = -ENXIO;
            goto probe_error;
        }
        err = usb_driver_claim_interface(&ua101_driver,
                         ua->intf[i], ua);
        if (err < 0) {
            ua->intf[i] = NULL;
            err = -EBUSY;
            goto probe_error;
        }
    }

    snd_card_set_dev(card, &interface->dev);

    err = detect_usb_format(ua);
    if (err < 0)
        goto probe_error;

    name = usb_id->idProduct == 0x0044 ? "UA-1000" : "UA-101";
    strcpy(card->driver, "UA-101");
    strcpy(card->shortname, name);
    usb_make_path(ua->dev, usb_path, sizeof(usb_path));
    snprintf(ua->card->longname, sizeof(ua->card->longname),
         "EDIROL %s (serial %s), %u Hz at %s, %s speed", name,
         ua->dev->serial ? ua->dev->serial : "?", ua->rate, usb_path,
         ua->dev->speed == USB_SPEED_HIGH ? "high" : "full");

    err = alloc_stream_buffers(ua, &ua->capture);
    if (err < 0)
        goto probe_error;
    err = alloc_stream_buffers(ua, &ua->playback);
    if (err < 0)
        goto probe_error;

    err = alloc_stream_urbs(ua, &ua->capture, capture_urb_complete);
    if (err < 0)
        goto probe_error;
    err = alloc_stream_urbs(ua, &ua->playback, playback_urb_complete);
    if (err < 0)
        goto probe_error;

    err = snd_pcm_new(card, name, 0, 1, 1, &ua->pcm);
    if (err < 0)
        goto probe_error;
    ua->pcm->private_data = ua;
    strcpy(ua->pcm->name, name);
    snd_pcm_set_ops(ua->pcm, SNDRV_PCM_STREAM_PLAYBACK, &playback_pcm_ops);
    snd_pcm_set_ops(ua->pcm, SNDRV_PCM_STREAM_CAPTURE, &capture_pcm_ops);

    err = snd_usbmidi_create(card, ua->intf[INTF_MIDI],
                 &ua->midi_list, &midi_quirk);
    if (err < 0)
        goto probe_error;

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

    usb_set_intfdata(interface, ua);
    devices_used |= 1 << card_index;

    mutex_unlock(&devices_mutex);
    return 0;

probe_error:
    free_usb_related_resources(ua, interface);
    snd_card_free(card);
    mutex_unlock(&devices_mutex);
    return err;
}

static void ua101_disconnect(struct usb_interface *interface)
{
    struct ua101 *ua = usb_get_intfdata(interface);
    struct list_head *midi;

    if (!ua)
        return;

    mutex_lock(&devices_mutex);

    set_bit(DISCONNECTED, &ua->states);
    wake_up(&ua->rate_feedback_wait);

    /* make sure that userspace cannot create new requests */
    snd_card_disconnect(ua->card);

    /* make sure that there are no pending USB requests */
    __list_for_each(midi, &ua->midi_list)
        snd_usbmidi_disconnect(midi);
    abort_alsa_playback(ua);
    abort_alsa_capture(ua);
    mutex_lock(&ua->mutex);
    stop_usb_playback(ua);
    stop_usb_capture(ua);
    mutex_unlock(&ua->mutex);

    free_usb_related_resources(ua, interface);

    devices_used &= ~(1 << ua->card_index);

    snd_card_free_when_closed(ua->card);

    mutex_unlock(&devices_mutex);
}

static struct usb_device_id ua101_ids[] = {
    { USB_DEVICE(0x0582, 0x0044) }, /* UA-1000 high speed */
    { USB_DEVICE(0x0582, 0x007d) }, /* UA-101 high speed */
    { USB_DEVICE(0x0582, 0x008d) }, /* UA-101 full speed */
    { }
};
MODULE_DEVICE_TABLE(usb, ua101_ids);

static struct usb_driver ua101_driver = {
    .name = "snd-ua101",
    .id_table = ua101_ids,
    .probe = ua101_probe,
    .disconnect = ua101_disconnect,
#if 0
    .suspend = ua101_suspend,
    .resume = ua101_resume,
#endif
};

module_usb_driver(ua101_driver);