seq_virmidi.c

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/*
 *  Virtual Raw MIDI client on Sequencer
 *
 *  Copyright (c) 2000 by Takashi Iwai <[email protected]>,
 *                        Jaroslav Kysela <[email protected]>
 *
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation; either version 2 of the License, or
 *   (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program; if not, write to the Free Software
 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
 *
 */

/*
 * Virtual Raw MIDI client
 *
 * The virtual rawmidi client is a sequencer client which associate
 * a rawmidi device file.  The created rawmidi device file can be
 * accessed as a normal raw midi, but its MIDI source and destination
 * are arbitrary.  For example, a user-client software synth connected
 * to this port can be used as a normal midi device as well.
 *
 * The virtual rawmidi device accepts also multiple opens.  Each file
 * has its own input buffer, so that no conflict would occur.  The drain
 * of input/output buffer acts only to the local buffer.
 *
 */

#include <linux/init.h>
#include <linux/wait.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <sound/core.h>
#include <sound/rawmidi.h>
#include <sound/info.h>
#include <sound/control.h>
#include <sound/minors.h>
#include <sound/seq_kernel.h>
#include <sound/seq_midi_event.h>
#include <sound/seq_virmidi.h>

MODULE_AUTHOR("Takashi Iwai <[email protected]>");
MODULE_DESCRIPTION("Virtual Raw MIDI client on Sequencer");
MODULE_LICENSE("GPL");

/*
 * initialize an event record
 */
static void snd_virmidi_init_event(struct snd_virmidi *vmidi,
                   struct snd_seq_event *ev)
{
    memset(ev, 0, sizeof(*ev));
    ev->source.port = vmidi->port;
    switch (vmidi->seq_mode) {
    case SNDRV_VIRMIDI_SEQ_DISPATCH:
        ev->dest.client = SNDRV_SEQ_ADDRESS_SUBSCRIBERS;
        break;
    case SNDRV_VIRMIDI_SEQ_ATTACH:
        /* FIXME: source and destination are same - not good.. */
        ev->dest.client = vmidi->client;
        ev->dest.port = vmidi->port;
        break;
    }
    ev->type = SNDRV_SEQ_EVENT_NONE;
}

/*
 * decode input event and put to read buffer of each opened file
 */
static int snd_virmidi_dev_receive_event(struct snd_virmidi_dev *rdev,
                     struct snd_seq_event *ev)
{
    struct snd_virmidi *vmidi;
    unsigned char msg[4];
    int len;

    read_lock(&rdev->filelist_lock);
    list_for_each_entry(vmidi, &rdev->filelist, list) {
        if (!vmidi->trigger)
            continue;
        if (ev->type == SNDRV_SEQ_EVENT_SYSEX) {
            if ((ev->flags & SNDRV_SEQ_EVENT_LENGTH_MASK) != SNDRV_SEQ_EVENT_LENGTH_VARIABLE)
                continue;
            snd_seq_dump_var_event(ev, (snd_seq_dump_func_t)snd_rawmidi_receive, vmidi->substream);
        } else {
            len = snd_midi_event_decode(vmidi->parser, msg, sizeof(msg), ev);
            if (len > 0)
                snd_rawmidi_receive(vmidi->substream, msg, len);
        }
    }
    read_unlock(&rdev->filelist_lock);

    return 0;
}

/*
 * receive an event from the remote virmidi port
 *
 * for rawmidi inputs, you can call this function from the event
 * handler of a remote port which is attached to the virmidi via
 * SNDRV_VIRMIDI_SEQ_ATTACH.
 */
#if 0
int snd_virmidi_receive(struct snd_rawmidi *rmidi, struct snd_seq_event *ev)
{
    struct snd_virmidi_dev *rdev;

    rdev = rmidi->private_data;
    return snd_virmidi_dev_receive_event(rdev, ev);
}
#endif  /*  0  */

/*
 * event handler of virmidi port
 */
static int snd_virmidi_event_input(struct snd_seq_event *ev, int direct,
                   void *private_data, int atomic, int hop)
{
    struct snd_virmidi_dev *rdev;

    rdev = private_data;
    if (!(rdev->flags & SNDRV_VIRMIDI_USE))
        return 0; /* ignored */
    return snd_virmidi_dev_receive_event(rdev, ev);
}

/*
 * trigger rawmidi stream for input
 */
static void snd_virmidi_input_trigger(struct snd_rawmidi_substream *substream, int up)
{
    struct snd_virmidi *vmidi = substream->runtime->private_data;

    if (up) {
        vmidi->trigger = 1;
    } else {
        vmidi->trigger = 0;
    }
}

/*
 * trigger rawmidi stream for output
 */
static void snd_virmidi_output_trigger(struct snd_rawmidi_substream *substream, int up)
{
    struct snd_virmidi *vmidi = substream->runtime->private_data;
    int count, res;
    unsigned char buf[32], *pbuf;

    if (up) {
        vmidi->trigger = 1;
        if (vmidi->seq_mode == SNDRV_VIRMIDI_SEQ_DISPATCH &&
            !(vmidi->rdev->flags & SNDRV_VIRMIDI_SUBSCRIBE)) {
            snd_rawmidi_transmit_ack(substream, substream->runtime->buffer_size - substream->runtime->avail);
            return;     /* ignored */
        }
        if (vmidi->event.type != SNDRV_SEQ_EVENT_NONE) {
            if (snd_seq_kernel_client_dispatch(vmidi->client, &vmidi->event, in_atomic(), 0) < 0)
                return;
            vmidi->event.type = SNDRV_SEQ_EVENT_NONE;
        }
        while (1) {
            count = snd_rawmidi_transmit_peek(substream, buf, sizeof(buf));
            if (count <= 0)
                break;
            pbuf = buf;
            while (count > 0) {
                res = snd_midi_event_encode(vmidi->parser, pbuf, count, &vmidi->event);
                if (res < 0) {
                    snd_midi_event_reset_encode(vmidi->parser);
                    continue;
                }
                snd_rawmidi_transmit_ack(substream, res);
                pbuf += res;
                count -= res;
                if (vmidi->event.type != SNDRV_SEQ_EVENT_NONE) {
                    if (snd_seq_kernel_client_dispatch(vmidi->client, &vmidi->event, in_atomic(), 0) < 0)
                        return;
                    vmidi->event.type = SNDRV_SEQ_EVENT_NONE;
                }
            }
        }
    } else {
        vmidi->trigger = 0;
    }
}

/*
 * open rawmidi handle for input
 */
static int snd_virmidi_input_open(struct snd_rawmidi_substream *substream)
{
    struct snd_virmidi_dev *rdev = substream->rmidi->private_data;
    struct snd_rawmidi_runtime *runtime = substream->runtime;
    struct snd_virmidi *vmidi;
    unsigned long flags;

    vmidi = kzalloc(sizeof(*vmidi), GFP_KERNEL);
    if (vmidi == NULL)
        return -ENOMEM;
    vmidi->substream = substream;
    if (snd_midi_event_new(0, &vmidi->parser) < 0) {
        kfree(vmidi);
        return -ENOMEM;
    }
    vmidi->seq_mode = rdev->seq_mode;
    vmidi->client = rdev->client;
    vmidi->port = rdev->port;   
    runtime->private_data = vmidi;
    write_lock_irqsave(&rdev->filelist_lock, flags);
    list_add_tail(&vmidi->list, &rdev->filelist);
    write_unlock_irqrestore(&rdev->filelist_lock, flags);
    vmidi->rdev = rdev;
    return 0;
}

/*
 * open rawmidi handle for output
 */
static int snd_virmidi_output_open(struct snd_rawmidi_substream *substream)
{
    struct snd_virmidi_dev *rdev = substream->rmidi->private_data;
    struct snd_rawmidi_runtime *runtime = substream->runtime;
    struct snd_virmidi *vmidi;

    vmidi = kzalloc(sizeof(*vmidi), GFP_KERNEL);
    if (vmidi == NULL)
        return -ENOMEM;
    vmidi->substream = substream;
    if (snd_midi_event_new(MAX_MIDI_EVENT_BUF, &vmidi->parser) < 0) {
        kfree(vmidi);
        return -ENOMEM;
    }
    vmidi->seq_mode = rdev->seq_mode;
    vmidi->client = rdev->client;
    vmidi->port = rdev->port;
    snd_virmidi_init_event(vmidi, &vmidi->event);
    vmidi->rdev = rdev;
    runtime->private_data = vmidi;
    return 0;
}

/*
 * close rawmidi handle for input
 */
static int snd_virmidi_input_close(struct snd_rawmidi_substream *substream)
{
    struct snd_virmidi *vmidi = substream->runtime->private_data;
    snd_midi_event_free(vmidi->parser);
    list_del(&vmidi->list);
    substream->runtime->private_data = NULL;
    kfree(vmidi);
    return 0;
}

/*
 * close rawmidi handle for output
 */
static int snd_virmidi_output_close(struct snd_rawmidi_substream *substream)
{
    struct snd_virmidi *vmidi = substream->runtime->private_data;
    snd_midi_event_free(vmidi->parser);
    substream->runtime->private_data = NULL;
    kfree(vmidi);
    return 0;
}

/*
 * subscribe callback - allow output to rawmidi device
 */
static int snd_virmidi_subscribe(void *private_data,
                 struct snd_seq_port_subscribe *info)
{
    struct snd_virmidi_dev *rdev;

    rdev = private_data;
    if (!try_module_get(rdev->card->module))
        return -EFAULT;
    rdev->flags |= SNDRV_VIRMIDI_SUBSCRIBE;
    return 0;
}

/*
 * unsubscribe callback - disallow output to rawmidi device
 */
static int snd_virmidi_unsubscribe(void *private_data,
                   struct snd_seq_port_subscribe *info)
{
    struct snd_virmidi_dev *rdev;

    rdev = private_data;
    rdev->flags &= ~SNDRV_VIRMIDI_SUBSCRIBE;
    module_put(rdev->card->module);
    return 0;
}


/*
 * use callback - allow input to rawmidi device
 */
static int snd_virmidi_use(void *private_data,
               struct snd_seq_port_subscribe *info)
{
    struct snd_virmidi_dev *rdev;

    rdev = private_data;
    if (!try_module_get(rdev->card->module))
        return -EFAULT;
    rdev->flags |= SNDRV_VIRMIDI_USE;
    return 0;
}

/*
 * unuse callback - disallow input to rawmidi device
 */
static int snd_virmidi_unuse(void *private_data,
                 struct snd_seq_port_subscribe *info)
{
    struct snd_virmidi_dev *rdev;

    rdev = private_data;
    rdev->flags &= ~SNDRV_VIRMIDI_USE;
    module_put(rdev->card->module);
    return 0;
}


/*
 *  Register functions
 */

static struct snd_rawmidi_ops snd_virmidi_input_ops = {
    .open = snd_virmidi_input_open,
    .close = snd_virmidi_input_close,
    .trigger = snd_virmidi_input_trigger,
};

static struct snd_rawmidi_ops snd_virmidi_output_ops = {
    .open = snd_virmidi_output_open,
    .close = snd_virmidi_output_close,
    .trigger = snd_virmidi_output_trigger,
};

/*
 * create a sequencer client and a port
 */
static int snd_virmidi_dev_attach_seq(struct snd_virmidi_dev *rdev)
{
    int client;
    struct snd_seq_port_callback pcallbacks;
    struct snd_seq_port_info *pinfo;
    int err;

    if (rdev->client >= 0)
        return 0;

    pinfo = kzalloc(sizeof(*pinfo), GFP_KERNEL);
    if (!pinfo) {
        err = -ENOMEM;
        goto __error;
    }

    client = snd_seq_create_kernel_client(rdev->card, rdev->device,
                          "%s %d-%d", rdev->rmidi->name,
                          rdev->card->number,
                          rdev->device);
    if (client < 0) {
        err = client;
        goto __error;
    }
    rdev->client = client;

    /* create a port */
    pinfo->addr.client = client;
    sprintf(pinfo->name, "VirMIDI %d-%d", rdev->card->number, rdev->device);
    /* set all capabilities */
    pinfo->capability |= SNDRV_SEQ_PORT_CAP_WRITE | SNDRV_SEQ_PORT_CAP_SYNC_WRITE | SNDRV_SEQ_PORT_CAP_SUBS_WRITE;
    pinfo->capability |= SNDRV_SEQ_PORT_CAP_READ | SNDRV_SEQ_PORT_CAP_SYNC_READ | SNDRV_SEQ_PORT_CAP_SUBS_READ;
    pinfo->capability |= SNDRV_SEQ_PORT_CAP_DUPLEX;
    pinfo->type = SNDRV_SEQ_PORT_TYPE_MIDI_GENERIC
        | SNDRV_SEQ_PORT_TYPE_SOFTWARE
        | SNDRV_SEQ_PORT_TYPE_PORT;
    pinfo->midi_channels = 16;
    memset(&pcallbacks, 0, sizeof(pcallbacks));
    pcallbacks.owner = THIS_MODULE;
    pcallbacks.private_data = rdev;
    pcallbacks.subscribe = snd_virmidi_subscribe;
    pcallbacks.unsubscribe = snd_virmidi_unsubscribe;
    pcallbacks.use = snd_virmidi_use;
    pcallbacks.unuse = snd_virmidi_unuse;
    pcallbacks.event_input = snd_virmidi_event_input;
    pinfo->kernel = &pcallbacks;
    err = snd_seq_kernel_client_ctl(client, SNDRV_SEQ_IOCTL_CREATE_PORT, pinfo);
    if (err < 0) {
        snd_seq_delete_kernel_client(client);
        rdev->client = -1;
        goto __error;
    }

    rdev->port = pinfo->addr.port;
    err = 0; /* success */

 __error:
    kfree(pinfo);
    return err;
}


/*
 * release the sequencer client
 */
static void snd_virmidi_dev_detach_seq(struct snd_virmidi_dev *rdev)
{
    if (rdev->client >= 0) {
        snd_seq_delete_kernel_client(rdev->client);
        rdev->client = -1;
    }
}

/*
 * register the device
 */
static int snd_virmidi_dev_register(struct snd_rawmidi *rmidi)
{
    struct snd_virmidi_dev *rdev = rmidi->private_data;
    int err;

    switch (rdev->seq_mode) {
    case SNDRV_VIRMIDI_SEQ_DISPATCH:
        err = snd_virmidi_dev_attach_seq(rdev);
        if (err < 0)
            return err;
        break;
    case SNDRV_VIRMIDI_SEQ_ATTACH:
        if (rdev->client == 0)
            return -EINVAL;
        /* should check presence of port more strictly.. */
        break;
    default:
        snd_printk(KERN_ERR "seq_mode is not set: %d\n", rdev->seq_mode);
        return -EINVAL;
    }
    return 0;
}


/*
 * unregister the device
 */
static int snd_virmidi_dev_unregister(struct snd_rawmidi *rmidi)
{
    struct snd_virmidi_dev *rdev = rmidi->private_data;

    if (rdev->seq_mode == SNDRV_VIRMIDI_SEQ_DISPATCH)
        snd_virmidi_dev_detach_seq(rdev);
    return 0;
}

/*
 *
 */
static struct snd_rawmidi_global_ops snd_virmidi_global_ops = {
    .dev_register = snd_virmidi_dev_register,
    .dev_unregister = snd_virmidi_dev_unregister,
};

/*
 * free device
 */
static void snd_virmidi_free(struct snd_rawmidi *rmidi)
{
    struct snd_virmidi_dev *rdev = rmidi->private_data;
    kfree(rdev);
}

/*
 * create a new device
 *
 */
/* exported */
int snd_virmidi_new(struct snd_card *card, int device, struct snd_rawmidi **rrmidi)
{
    struct snd_rawmidi *rmidi;
    struct snd_virmidi_dev *rdev;
    int err;
    
    *rrmidi = NULL;
    if ((err = snd_rawmidi_new(card, "VirMidi", device,
                   16,  /* may be configurable */
                   16,  /* may be configurable */
                   &rmidi)) < 0)
        return err;
    strcpy(rmidi->name, rmidi->id);
    rdev = kzalloc(sizeof(*rdev), GFP_KERNEL);
    if (rdev == NULL) {
        snd_device_free(card, rmidi);
        return -ENOMEM;
    }
    rdev->card = card;
    rdev->rmidi = rmidi;
    rdev->device = device;
    rdev->client = -1;
    rwlock_init(&rdev->filelist_lock);
    INIT_LIST_HEAD(&rdev->filelist);
    rdev->seq_mode = SNDRV_VIRMIDI_SEQ_DISPATCH;
    rmidi->private_data = rdev;
    rmidi->private_free = snd_virmidi_free;
    rmidi->ops = &snd_virmidi_global_ops;
    snd_rawmidi_set_ops(rmidi, SNDRV_RAWMIDI_STREAM_INPUT, &snd_virmidi_input_ops);
    snd_rawmidi_set_ops(rmidi, SNDRV_RAWMIDI_STREAM_OUTPUT, &snd_virmidi_output_ops);
    rmidi->info_flags = SNDRV_RAWMIDI_INFO_INPUT |
                SNDRV_RAWMIDI_INFO_OUTPUT |
                SNDRV_RAWMIDI_INFO_DUPLEX;
    *rrmidi = rmidi;
    return 0;
}

/*
 *  ENTRY functions
 */

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

static void __exit alsa_virmidi_exit(void)
{
}

module_init(alsa_virmidi_init)
module_exit(alsa_virmidi_exit)

EXPORT_SYMBOL(snd_virmidi_new);