virmidi.c

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/*
 *  Dummy soundcard for virtual rawmidi devices
 *
 *  Copyright (c) 2000 by Takashi Iwai <[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 DEVICE CARDS
 *
 * This dummy card contains up to 4 virtual rawmidi devices.
 * They are not real rawmidi devices but just associated with sequencer
 * clients, so that any input/output sources can be connected as a raw
 * MIDI device arbitrary.
 * Also, multiple access is allowed to a single rawmidi device.
 *
 * Typical usage is like following:
 * - Load snd-virmidi module.
 *  # modprobe snd-virmidi index=2
 *   Then, sequencer clients 72:0 to 75:0 will be created, which are
 *   mapped from /dev/snd/midiC1D0 to /dev/snd/midiC1D3, respectively.
 *
 * - Connect input/output via aconnect.
 *  % aconnect 64:0 72:0    # keyboard input redirection 64:0 -> 72:0
 *  % aconnect 72:0 65:0    # output device redirection 72:0 -> 65:0
 *
 * - Run application using a midi device (eg. /dev/snd/midiC1D0)
 */

#include <linux/init.h>
#include <linux/wait.h>
#include <linux/err.h>
#include <linux/platform_device.h>
#include <linux/module.h>
#include <sound/core.h>
#include <sound/seq_kernel.h>
#include <sound/seq_virmidi.h>
#include <sound/initval.h>

/* hack: OSS defines midi_devs, so undefine it (versioned symbols) */
#undef midi_devs

MODULE_AUTHOR("Takashi Iwai <[email protected]>");
MODULE_DESCRIPTION("Dummy soundcard for virtual rawmidi devices");
MODULE_LICENSE("GPL");
MODULE_SUPPORTED_DEVICE("{{ALSA,Virtual rawmidi device}}");

#define MAX_MIDI_DEVICES    4

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] = {1, [1 ... (SNDRV_CARDS - 1)] = 0};
static int midi_devs[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS - 1)] = 4};

module_param_array(index, int, NULL, 0444);
MODULE_PARM_DESC(index, "Index value for virmidi soundcard.");
module_param_array(id, charp, NULL, 0444);
MODULE_PARM_DESC(id, "ID string for virmidi soundcard.");
module_param_array(enable, bool, NULL, 0444);
MODULE_PARM_DESC(enable, "Enable this soundcard.");
module_param_array(midi_devs, int, NULL, 0444);
MODULE_PARM_DESC(midi_devs, "MIDI devices # (1-4)");

struct snd_card_virmidi {
    struct snd_card *card;
    struct snd_rawmidi *midi[MAX_MIDI_DEVICES];
};

static struct platform_device *devices[SNDRV_CARDS];


static int __devinit snd_virmidi_probe(struct platform_device *devptr)
{
    struct snd_card *card;
    struct snd_card_virmidi *vmidi;
    int idx, err;
    int dev = devptr->id;

    err = snd_card_create(index[dev], id[dev], THIS_MODULE,
                  sizeof(struct snd_card_virmidi), &card);
    if (err < 0)
        return err;
    vmidi = card->private_data;
    vmidi->card = card;

    if (midi_devs[dev] > MAX_MIDI_DEVICES) {
        snd_printk(KERN_WARNING
               "too much midi devices for virmidi %d: "
               "force to use %d\n", dev, MAX_MIDI_DEVICES);
        midi_devs[dev] = MAX_MIDI_DEVICES;
    }
    for (idx = 0; idx < midi_devs[dev]; idx++) {
        struct snd_rawmidi *rmidi;
        struct snd_virmidi_dev *rdev;
        if ((err = snd_virmidi_new(card, idx, &rmidi)) < 0)
            goto __nodev;
        rdev = rmidi->private_data;
        vmidi->midi[idx] = rmidi;
        strcpy(rmidi->name, "Virtual Raw MIDI");
        rdev->seq_mode = SNDRV_VIRMIDI_SEQ_DISPATCH;
    }
    
    strcpy(card->driver, "VirMIDI");
    strcpy(card->shortname, "VirMIDI");
    sprintf(card->longname, "Virtual MIDI Card %i", dev + 1);

    snd_card_set_dev(card, &devptr->dev);

    if ((err = snd_card_register(card)) == 0) {
        platform_set_drvdata(devptr, card);
        return 0;
    }
      __nodev:
    snd_card_free(card);
    return err;
}

static int __devexit snd_virmidi_remove(struct platform_device *devptr)
{
    snd_card_free(platform_get_drvdata(devptr));
    platform_set_drvdata(devptr, NULL);
    return 0;
}

#define SND_VIRMIDI_DRIVER  "snd_virmidi"

static struct platform_driver snd_virmidi_driver = {
    .probe      = snd_virmidi_probe,
    .remove     = __devexit_p(snd_virmidi_remove),
    .driver     = {
        .name   = SND_VIRMIDI_DRIVER,
        .owner  = THIS_MODULE,
    },
};

static void snd_virmidi_unregister_all(void)
{
    int i;

    for (i = 0; i < ARRAY_SIZE(devices); ++i)
        platform_device_unregister(devices[i]);
    platform_driver_unregister(&snd_virmidi_driver);
}

static int __init alsa_card_virmidi_init(void)
{
    int i, cards, err;

    if ((err = platform_driver_register(&snd_virmidi_driver)) < 0)
        return err;

    cards = 0;
    for (i = 0; i < SNDRV_CARDS; i++) {
        struct platform_device *device;
        if (! enable[i])
            continue;
        device = platform_device_register_simple(SND_VIRMIDI_DRIVER,
                             i, NULL, 0);
        if (IS_ERR(device))
            continue;
        if (!platform_get_drvdata(device)) {
            platform_device_unregister(device);
            continue;
        }
        devices[i] = device;
        cards++;
    }
    if (!cards) {
#ifdef MODULE
        printk(KERN_ERR "Card-VirMIDI soundcard not found or device busy\n");
#endif
        snd_virmidi_unregister_all();
        return -ENODEV;
    }
    return 0;
}

static void __exit alsa_card_virmidi_exit(void)
{
    snd_virmidi_unregister_all();
}

module_init(alsa_card_virmidi_init)
module_exit(alsa_card_virmidi_exit)