source: GPL/trunk/alsa-kernel/drivers/virmidi.c@ 679

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *  Dummy soundcard for virtual rawmidi devices
 *
 *  Copyright (c) 2000 by Takashi Iwai <tiwai@suse.de>
 */

/*
 * 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 <tiwai@suse.de>");
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 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_new(&devptr->dev, 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;

                err = snd_virmidi_new(card, idx, &rmidi);
                if (err < 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);

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

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

#define SND_VIRMIDI_DRIVER      "snd_virmidi"

static struct platform_driver snd_virmidi_driver = {
        .probe          = snd_virmidi_probe,
        .remove         = snd_virmidi_remove,
        .driver         = {
                .name   = SND_VIRMIDI_DRIVER,
        },
};

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;

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