source: GPL/alsa-kernel/drivers/virmidi.c@ 1

/*
 *  Dummy soundcard for virtual rawmidi devices
 *
 *  Copyright (c) 2000 by Takashi Iwai <tiwai@suse.de>
 *
 *   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., 675 Mass Ave, Cambridge, MA 02139, 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-card-virmidi module.
 *      # modprobe snd-card-virmidi snd_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)
 */

#define SNDRV_MAIN_OBJECT_FILE
#include <sound/driver.h>
#include <sound/seq_kernel.h>
#include <sound/seq_virmidi.h>
#define SNDRV_GET_ID
#include <sound/initval.h>

EXPORT_NO_SYMBOLS;
MODULE_DESCRIPTION("Dummy soundcard for virtual rawmidi devices");
MODULE_CLASSES("{sound}");
MODULE_DEVICES("{{ALSA,Virtual rawmidi device}}");

#define MAX_MIDI_DEVICES        8

static int snd_index[SNDRV_CARDS] = SNDRV_DEFAULT_IDX;  /* Index 0-MAX */
static char *snd_id[SNDRV_CARDS] = SNDRV_DEFAULT_STR;   /* ID for this card */
#ifdef TARGET_OS2
static int snd_enable[SNDRV_CARDS] = SNDRV_DEFAULT_ENABLE;
static int snd_midi_devs[SNDRV_CARDS] = SNDDRV_DEFAULT_MIDI_DEVS
#else
    static int snd_enable[SNDRV_CARDS] = {1, [1 ... (SNDRV_CARDS - 1)] = 0};
static int snd_midi_devs[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS - 1)] = 4};
#endif

MODULE_PARM(snd_index, "1-" __MODULE_STRING(SNDRV_CARDS) "i");
MODULE_PARM_DESC(snd_index, "Index value for virmidi soundcard.");
MODULE_PARM_SYNTAX(snd_index, SNDRV_INDEX_DESC);
MODULE_PARM(snd_id, "1-" __MODULE_STRING(SNDRV_CARDS) "s");
MODULE_PARM_DESC(snd_id, "ID string for virmidi soundcard.");
MODULE_PARM_SYNTAX(snd_id, SNDRV_ID_DESC);
MODULE_PARM(snd_enable, "1-" __MODULE_STRING(SNDRV_CARDS) "i");
MODULE_PARM_DESC(snd_enable, "Enable this soundcard.");
MODULE_PARM_SYNTAX(snd_enable, SNDRV_ENABLE_DESC);
MODULE_PARM(snd_midi_devs, "1-" __MODULE_STRING(SNDRV_CARDS) "i");
MODULE_PARM_DESC(snd_midi_devs, "MIDI devices # (1-8)");
MODULE_PARM_SYNTAX(snd_midi_devs, SNDRV_ENABLED ",allows:{{1,8}}");

typedef struct snd_card_virmidi {
    snd_card_t *card;
    snd_rawmidi_t *midi[MAX_MIDI_DEVICES];
} snd_card_virmidi_t;

static snd_card_t *snd_virmidi_cards[SNDRV_CARDS] = SNDRV_DEFAULT_PTR;


static int __init snd_card_virmidi_probe(int dev)
{
    snd_card_t *card;
    struct snd_card_virmidi *vmidi;
    int idx, err;

    if (!snd_enable[dev])
        return -ENODEV;
    card = snd_card_new(snd_index[dev], snd_id[dev], THIS_MODULE,
                        sizeof(struct snd_card_virmidi));
    if (card == NULL)
        return -ENOMEM;
    vmidi = (struct snd_card_virmidi *)card->private_data;
    vmidi->card = card;

    if (snd_midi_devs[dev] > MAX_MIDI_DEVICES) {
        snd_printk("too much midi devices for virmidi %d: force to use %d\n", dev, MAX_MIDI_DEVICES);
        snd_midi_devs[dev] = MAX_MIDI_DEVICES;
    }
    for (idx = 0; idx < snd_midi_devs[dev]; idx++) {
        snd_rawmidi_t *rmidi;
        snd_virmidi_dev_t *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);
    if ((err = snd_card_register(card)) == 0) {
        snd_virmidi_cards[dev] = card;
        return 0;
    }
__nodev:
    snd_card_free(card);
    return err;
}

static int __init alsa_card_virmidi_init(void)
{
    int dev, cards;

    for (dev = cards = 0; dev < SNDRV_CARDS && snd_enable[dev]; dev++) {
        if (snd_card_virmidi_probe(dev) < 0) {
#ifdef MODULE
            snd_printk("Card-VirMIDI #%i not found or device busy\n", dev + 1);
#endif
            break;
        }
        cards++;
    }
    if (!cards) {
#ifdef MODULE
        snd_printk("Card-VirMIDI soundcard not found or device busy\n");
#endif
        return -ENODEV;
    }
    return 0;
}

static void __exit alsa_card_virmidi_exit(void)
{
    int dev;

    for (dev = 0; dev < SNDRV_CARDS; dev++)
        snd_card_free(snd_virmidi_cards[dev]);
}

module_init(alsa_card_virmidi_init)
module_exit(alsa_card_virmidi_exit)

#ifndef MODULE

/* format is: snd-card-virmidi=snd_enable,snd_index,snd_id,snd_midi_devs */

static int __init alsa_card_virmidi_setup(char *str)
{
    static unsigned __initdata nr_dev = 0;

    if (nr_dev >= SNDRV_CARDS)
        return 0;
    (void)(get_option(&str,&snd_enable[nr_dev]) == 2 &&
           get_option(&str,&snd_index[nr_dev]) == 2 &&
           get_id(&str,&snd_id[nr_dev]) == 2 &&
           get_option(&str,&snd_midi_devs[nr_dev]) == 2);
    nr_dev++;
    return 1;
}

__setup("snd-card-virmidi=", alsa_card_virmidi_setup);

#endif /* ifndef MODULE */