// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *      MOTU Midi Timepiece ALSA Main routines
 *      Copyright by Michael T. Mayers (c) Jan 09, 2000
 *      mail: michael@tweakoz.com
 *      Thanks to John Galbraith
 *
 *      This driver is for the 'Mark Of The Unicorn' (MOTU)
 *      MidiTimePiece AV multiport MIDI interface 
 *
 *      IOPORTS
 *      -------
 *      8 MIDI Ins and 8 MIDI outs
 *      Video Sync In (BNC), Word Sync Out (BNC), 
 *      ADAT Sync Out (DB9)
 *      SMPTE in/out (1/4")
 *      2 programmable pedal/footswitch inputs and 4 programmable MIDI controller knobs.
 *      Macintosh RS422 serial port
 *      RS422 "network" port for ganging multiple MTP's
 *      PC Parallel Port ( which this driver currently uses )
 *
 *      MISC FEATURES
 *      -------------
 *      Hardware MIDI routing, merging, and filtering   
 *      MIDI Synchronization to Video, ADAT, SMPTE and other Clock sources
 *      128 'scene' memories, recallable from MIDI program change
 *
 * ChangeLog
 * Jun 11 2001  Takashi Iwai <tiwai@suse.de>
 *      - Recoded & debugged
 *      - Added timer interrupt for midi outputs
 *      - hwports is between 1 and 8, which specifies the number of hardware ports.
 *        The three global ports, computer, adat and broadcast ports, are created
 *        always after h/w and remote ports.
 */

#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/err.h>
#include <linux/platform_device.h>
#include <linux/ioport.h>
#include <linux/io.h>
#include <linux/moduleparam.h>
#include <sound/core.h>
#include <sound/initval.h>
#include <sound/rawmidi.h>
#include <linux/delay.h>

/*
 *      globals
 */
MODULE_AUTHOR("Michael T. Mayers");
MODULE_DESCRIPTION("MOTU MidiTimePiece AV multiport MIDI");
MODULE_LICENSE("GPL");
MODULE_SUPPORTED_DEVICE("{{MOTU,MidiTimePiece AV multiport MIDI}}");

// io resources
#define MTPAV_IOBASE            0x378
#define MTPAV_IRQ               7
#define MTPAV_MAX_PORTS         8

static int index = SNDRV_DEFAULT_IDX1;
static char *id = SNDRV_DEFAULT_STR1;
static long port = MTPAV_IOBASE;        /* 0x378, 0x278 */
static int irq = MTPAV_IRQ;             /* 7, 5 */
static int hwports = MTPAV_MAX_PORTS;   /* use hardware ports 1-8 */

module_param(index, int, 0444);
MODULE_PARM_DESC(index, "Index value for MotuMTPAV MIDI.");
module_param(id, charp, 0444);
MODULE_PARM_DESC(id, "ID string for MotuMTPAV MIDI.");
module_param_hw(port, long, ioport, 0444);
MODULE_PARM_DESC(port, "Parallel port # for MotuMTPAV MIDI.");
module_param_hw(irq, int, irq, 0444);
MODULE_PARM_DESC(irq, "Parallel IRQ # for MotuMTPAV MIDI.");
module_param(hwports, int, 0444);
MODULE_PARM_DESC(hwports, "Hardware ports # for MotuMTPAV MIDI.");

static struct platform_device *device;

/*
 *      defines
 */
//#define USE_FAKE_MTP //       don't actually read/write to MTP device (for debugging without an actual unit) (does not work yet)

// parallel port usage masks
#define SIGS_BYTE 0x08
#define SIGS_RFD 0x80
#define SIGS_IRQ 0x40
#define SIGS_IN0 0x10
#define SIGS_IN1 0x20

#define SIGC_WRITE 0x04
#define SIGC_READ 0x08
#define SIGC_INTEN 0x10

#define DREG 0
#define SREG 1
#define CREG 2

//
#define MTPAV_MODE_INPUT_OPENED         0x01
#define MTPAV_MODE_OUTPUT_OPENED        0x02
#define MTPAV_MODE_INPUT_TRIGGERED      0x04
#define MTPAV_MODE_OUTPUT_TRIGGERED     0x08

#define NUMPORTS (0x12+1)


/*
 */

struct mtpav_port {
        u8 number;
        u8 hwport;
        u8 mode;
        u8 running_status;
        struct snd_rawmidi_substream *input;
        struct snd_rawmidi_substream *output;
};

struct mtpav {
        struct snd_card *card;
        unsigned long port;
        struct resource *res_port;
        int irq;                        /* interrupt (for inputs) */
        spinlock_t spinlock;
        int share_irq;                  /* number of accesses to input interrupts */
        int istimer;                    /* number of accesses to timer interrupts */
        struct timer_list timer;        /* timer interrupts for outputs */
        struct snd_rawmidi *rmidi;
        int num_ports;          /* number of hw ports (1-8) */
        struct mtpav_port ports[NUMPORTS];      /* all ports including computer, adat and bc */

        u32 inmidiport;         /* selected input midi port */
        u32 inmidistate;        /* during midi command 0xf5 */

        u32 outmidihwport;      /* selected output midi hw port */
};


/*
 * possible hardware ports (selected by 0xf5 port message)
 *      0x00            all ports
 *      0x01 .. 0x08    this MTP's ports 1..8
 *      0x09 .. 0x10    networked MTP's ports (9..16)
 *      0x11            networked MTP's computer port
 *      0x63            to ADAT
 *
 * mappig:
 *  subdevice 0 - (X-1)    ports
 *            X - (2*X-1)  networked ports
 *            X            computer
 *            X+1          ADAT
 *            X+2          all ports
 *
 *  where X = chip->num_ports
 */

#define MTPAV_PIDX_COMPUTER     0
#define MTPAV_PIDX_ADAT         1
#define MTPAV_PIDX_BROADCAST    2


static int translate_subdevice_to_hwport(struct mtpav *chip, int subdev)
{
        if (subdev < 0)
                return 0x01; /* invalid - use port 0 as default */
        else if (subdev < chip->num_ports)
                return subdev + 1; /* single mtp port */
        else if (subdev < chip->num_ports * 2)
                return subdev - chip->num_ports + 0x09; /* remote port */
        else if (subdev == chip->num_ports * 2 + MTPAV_PIDX_COMPUTER)
                return 0x11; /* computer port */
        else if (subdev == chip->num_ports + MTPAV_PIDX_ADAT)
                return 0x63;            /* ADAT */
        return 0; /* all ports */
}

static int translate_hwport_to_subdevice(struct mtpav *chip, int hwport)
{
        int p;
        if (hwport <= 0x00) /* all ports */
                return chip->num_ports + MTPAV_PIDX_BROADCAST;
        else if (hwport <= 0x08) { /* single port */
                p = hwport - 1;
                if (p >= chip->num_ports)
                        p = 0;
                return p;
        } else if (hwport <= 0x10) { /* remote port */
                p = hwport - 0x09 + chip->num_ports;
                if (p >= chip->num_ports * 2)
                        p = chip->num_ports;
                return p;
        } else if (hwport == 0x11)  /* computer port */
                return chip->num_ports + MTPAV_PIDX_COMPUTER;
        else  /* ADAT */
                return chip->num_ports + MTPAV_PIDX_ADAT;
}


/*
 */

static u8 snd_mtpav_getreg(struct mtpav *chip, u16 reg)
{
        u8 rval = 0;

        if (reg == SREG) {
                rval = inb(chip->port + SREG);
                rval = (rval & 0xf8);
        } else if (reg == CREG) {
                rval = inb(chip->port + CREG);
                rval = (rval & 0x1c);
        }

        return rval;
}

/*
 */

static inline void snd_mtpav_mputreg(struct mtpav *chip, u16 reg, u8 val)
{
        if (reg == DREG || reg == CREG)
                outb(val, chip->port + reg);
}

/*
 */

static void snd_mtpav_wait_rfdhi(struct mtpav *chip)
{
        int counts = 10000;
        u8 sbyte;

        sbyte = snd_mtpav_getreg(chip, SREG);
        while (!(sbyte & SIGS_RFD) && counts--) {
                sbyte = snd_mtpav_getreg(chip, SREG);
                udelay(10);
        }
}

static void snd_mtpav_send_byte(struct mtpav *chip, u8 byte)
{
        u8 tcbyt;
        u8 clrwrite;
        u8 setwrite;

        snd_mtpav_wait_rfdhi(chip);

        /////////////////

        tcbyt = snd_mtpav_getreg(chip, CREG);
        clrwrite = tcbyt & (SIGC_WRITE ^ 0xff);
        setwrite = tcbyt | SIGC_WRITE;

        snd_mtpav_mputreg(chip, DREG, byte);
        snd_mtpav_mputreg(chip, CREG, clrwrite);        // clear write bit

        snd_mtpav_mputreg(chip, CREG, setwrite);        // set write bit

}


/*
 */

/* call this with spin lock held */
static void snd_mtpav_output_port_write(struct mtpav *mtp_card,
                                        struct mtpav_port *portp,
                                        struct snd_rawmidi_substream *substream)
{
        u8 outbyte;

        // Get the outbyte first, so we can emulate running status if
        // necessary
        if (snd_rawmidi_transmit(substream, &outbyte, 1) != 1)
                return;

        // send port change command if necessary

        if (portp->hwport != mtp_card->outmidihwport) {
                mtp_card->outmidihwport = portp->hwport;

                snd_mtpav_send_byte(mtp_card, 0xf5);
                snd_mtpav_send_byte(mtp_card, portp->hwport);
                /*
                snd_printk(KERN_DEBUG "new outport: 0x%x\n",
                           (unsigned int) portp->hwport);
                */
                if (!(outbyte & 0x80) && portp->running_status)
                        snd_mtpav_send_byte(mtp_card, portp->running_status);
        }

        // send data

        do {
                if (outbyte & 0x80)
                        portp->running_status = outbyte;
                
                snd_mtpav_send_byte(mtp_card, outbyte);
        } while (snd_rawmidi_transmit(substream, &outbyte, 1) == 1);
}

static void snd_mtpav_output_write(struct snd_rawmidi_substream *substream)
{
        struct mtpav *mtp_card = substream->rmidi->private_data;
        struct mtpav_port *portp = &mtp_card->ports[substream->number];
        unsigned long flags;

        spin_lock_irqsave(&mtp_card->spinlock, flags);
        snd_mtpav_output_port_write(mtp_card, portp, substream);
        spin_unlock_irqrestore(&mtp_card->spinlock, flags);
}


/*
 *      mtpav control
 */

static void snd_mtpav_portscan(struct mtpav *chip)      // put mtp into smart routing mode
{
        u8 p;

        for (p = 0; p < 8; p++) {
                snd_mtpav_send_byte(chip, 0xf5);
                snd_mtpav_send_byte(chip, p);
                snd_mtpav_send_byte(chip, 0xfe);
        }
}

/*
 */

static int snd_mtpav_input_open(struct snd_rawmidi_substream *substream)
{
        struct mtpav *mtp_card = substream->rmidi->private_data;
        struct mtpav_port *portp = &mtp_card->ports[substream->number];
        unsigned long flags;

        spin_lock_irqsave(&mtp_card->spinlock, flags);
        portp->mode |= MTPAV_MODE_INPUT_OPENED;
        portp->input = substream;
        if (mtp_card->share_irq++ == 0)
                snd_mtpav_mputreg(mtp_card, CREG, (SIGC_INTEN | SIGC_WRITE));   // enable pport interrupts
        spin_unlock_irqrestore(&mtp_card->spinlock, flags);
        return 0;
}

/*
 */

static int snd_mtpav_input_close(struct snd_rawmidi_substream *substream)
{
        struct mtpav *mtp_card = substream->rmidi->private_data;
        struct mtpav_port *portp = &mtp_card->ports[substream->number];
        unsigned long flags;

        spin_lock_irqsave(&mtp_card->spinlock, flags);
        portp->mode &= ~MTPAV_MODE_INPUT_OPENED;
        portp->input = NULL;
        if (--mtp_card->share_irq == 0)
                snd_mtpav_mputreg(mtp_card, CREG, 0);   // disable pport interrupts
        spin_unlock_irqrestore(&mtp_card->spinlock, flags);
        return 0;
}

/*
 */

static void snd_mtpav_input_trigger(struct snd_rawmidi_substream *substream, int up)
{
        struct mtpav *mtp_card = substream->rmidi->private_data;
        struct mtpav_port *portp = &mtp_card->ports[substream->number];
        unsigned long flags;

        spin_lock_irqsave(&mtp_card->spinlock, flags);
        if (up)
                portp->mode |= MTPAV_MODE_INPUT_TRIGGERED;
        else
                portp->mode &= ~MTPAV_MODE_INPUT_TRIGGERED;
        spin_unlock_irqrestore(&mtp_card->spinlock, flags);

}


/*
 * timer interrupt for outputs
 */

static void snd_mtpav_output_timer(struct timer_list *t)
{
        unsigned long flags;
        struct mtpav *chip = from_timer(chip, t, timer);
        int p;

        spin_lock_irqsave(&chip->spinlock, flags);
        /* reprogram timer */
        mod_timer(&chip->timer, 1 + jiffies);
        /* process each port */
        for (p = 0; p <= chip->num_ports * 2 + MTPAV_PIDX_BROADCAST; p++) {
                struct mtpav_port *portp = &chip->ports[p];
                if ((portp->mode & MTPAV_MODE_OUTPUT_TRIGGERED) && portp->output)
                        snd_mtpav_output_port_write(chip, portp, portp->output);
        }
        spin_unlock_irqrestore(&chip->spinlock, flags);
}

/* spinlock held! */
static void snd_mtpav_add_output_timer(struct mtpav *chip)
{
        mod_timer(&chip->timer, 1 + jiffies);
}

/* spinlock held! */
static void snd_mtpav_remove_output_timer(struct mtpav *chip)
{
        del_timer(&chip->timer);
}

/*
 */

static int snd_mtpav_output_open(struct snd_rawmidi_substream *substream)
{
        struct mtpav *mtp_card = substream->rmidi->private_data;
        struct mtpav_port *portp = &mtp_card->ports[substream->number];
        unsigned long flags;

        spin_lock_irqsave(&mtp_card->spinlock, flags);
        portp->mode |= MTPAV_MODE_OUTPUT_OPENED;
        portp->output = substream;
        spin_unlock_irqrestore(&mtp_card->spinlock, flags);
        return 0;
};

/*
 */

static int snd_mtpav_output_close(struct snd_rawmidi_substream *substream)
{
        struct mtpav *mtp_card = substream->rmidi->private_data;
        struct mtpav_port *portp = &mtp_card->ports[substream->number];
        unsigned long flags;

        spin_lock_irqsave(&mtp_card->spinlock, flags);
        portp->mode &= ~MTPAV_MODE_OUTPUT_OPENED;
        portp->output = NULL;
        spin_unlock_irqrestore(&mtp_card->spinlock, flags);
        return 0;
};

/*
 */

static void snd_mtpav_output_trigger(struct snd_rawmidi_substream *substream, int up)
{
        struct mtpav *mtp_card = substream->rmidi->private_data;
        struct mtpav_port *portp = &mtp_card->ports[substream->number];
        unsigned long flags;

        spin_lock_irqsave(&mtp_card->spinlock, flags);
        if (up) {
                if (! (portp->mode & MTPAV_MODE_OUTPUT_TRIGGERED)) {
                        if (mtp_card->istimer++ == 0)
                                snd_mtpav_add_output_timer(mtp_card);
                        portp->mode |= MTPAV_MODE_OUTPUT_TRIGGERED;
                }
        } else {
                portp->mode &= ~MTPAV_MODE_OUTPUT_TRIGGERED;
                if (--mtp_card->istimer == 0)
                        snd_mtpav_remove_output_timer(mtp_card);
        }
        spin_unlock_irqrestore(&mtp_card->spinlock, flags);

        if (up)
                snd_mtpav_output_write(substream);
}

/*
 * midi interrupt for inputs
 */

static void snd_mtpav_inmidi_process(struct mtpav *mcrd, u8 inbyte)
{
        struct mtpav_port *portp;

        if ((int)mcrd->inmidiport > mcrd->num_ports * 2 + MTPAV_PIDX_BROADCAST)
                return;

        portp = &mcrd->ports[mcrd->inmidiport];
        if (portp->mode & MTPAV_MODE_INPUT_TRIGGERED)
                snd_rawmidi_receive(portp->input, &inbyte, 1);
}

static void snd_mtpav_inmidi_h(struct mtpav *mcrd, u8 inbyte)
{
        if (inbyte >= 0xf8) {
                /* real-time midi code */
                snd_mtpav_inmidi_process(mcrd, inbyte);
                return;
        }

        if (mcrd->inmidistate == 0) {   // awaiting command
                if (inbyte == 0xf5)     // MTP port #
                        mcrd->inmidistate = 1;
                else
                        snd_mtpav_inmidi_process(mcrd, inbyte);
        } else if (mcrd->inmidistate) {
                mcrd->inmidiport = translate_hwport_to_subdevice(mcrd, inbyte);
                mcrd->inmidistate = 0;
        }
}

static void snd_mtpav_read_bytes(struct mtpav *mcrd)
{
        u8 clrread, setread;
        u8 mtp_read_byte;
        u8 sr, cbyt;
        int i;

        u8 sbyt = snd_mtpav_getreg(mcrd, SREG);

        /* printk(KERN_DEBUG "snd_mtpav_read_bytes() sbyt: 0x%x\n", sbyt); */

        if (!(sbyt & SIGS_BYTE))
                return;

        cbyt = snd_mtpav_getreg(mcrd, CREG);
        clrread = cbyt & (SIGC_READ ^ 0xff);
        setread = cbyt | SIGC_READ;

        do {

                mtp_read_byte = 0;
                for (i = 0; i < 4; i++) {
                        snd_mtpav_mputreg(mcrd, CREG, setread);
                        sr = snd_mtpav_getreg(mcrd, SREG);
                        snd_mtpav_mputreg(mcrd, CREG, clrread);

                        sr &= SIGS_IN0 | SIGS_IN1;
                        sr >>= 4;
                        mtp_read_byte |= sr << (i * 2);
                }

                snd_mtpav_inmidi_h(mcrd, mtp_read_byte);

                sbyt = snd_mtpav_getreg(mcrd, SREG);

        } while (sbyt & SIGS_BYTE);
}

static irqreturn_t snd_mtpav_irqh(int irq, void *dev_id)
{
        struct mtpav *mcard = dev_id;

        spin_lock(&mcard->spinlock);
        snd_mtpav_read_bytes(mcard);
        spin_unlock(&mcard->spinlock);
        return IRQ_HANDLED;
}

/*
 * get ISA resources
 */
static int snd_mtpav_get_ISA(struct mtpav *mcard)
{
        if ((mcard->res_port = request_region(port, 3, "MotuMTPAV MIDI")) == NULL) {
                snd_printk(KERN_ERR "MTVAP port 0x%lx is busy\n", port);
                return -EBUSY;
        }
        mcard->port = port;
        if (request_irq(irq, snd_mtpav_irqh, 0, "MOTU MTPAV", mcard)) {
                snd_printk(KERN_ERR "MTVAP IRQ %d busy\n", irq);
                return -EBUSY;
        }
        mcard->irq = irq;
        return 0;
}


/*
 */

static const struct snd_rawmidi_ops snd_mtpav_output = {
        .open =         snd_mtpav_output_open,
        .close =        snd_mtpav_output_close,
        .trigger =      snd_mtpav_output_trigger,
};

static const struct snd_rawmidi_ops snd_mtpav_input = {
        .open =         snd_mtpav_input_open,
        .close =        snd_mtpav_input_close,
        .trigger =      snd_mtpav_input_trigger,
};


/*
 * get RAWMIDI resources
 */

static void snd_mtpav_set_name(struct mtpav *chip,
                               struct snd_rawmidi_substream *substream)
{
        if (substream->number >= 0 && substream->number < chip->num_ports)
                sprintf(substream->name, "MTP direct %d", (substream->number % chip->num_ports) + 1);
        else if (substream->number >= 8 && substream->number < chip->num_ports * 2)
                sprintf(substream->name, "MTP remote %d", (substream->number % chip->num_ports) + 1);
        else if (substream->number == chip->num_ports * 2)
                strcpy(substream->name, "MTP computer");
        else if (substream->number == chip->num_ports * 2 + 1)
                strcpy(substream->name, "MTP ADAT");
        else
                strcpy(substream->name, "MTP broadcast");
}

static int snd_mtpav_get_RAWMIDI(struct mtpav *mcard)
{
        int rval;
        struct snd_rawmidi *rawmidi;
        struct snd_rawmidi_substream *substream;
        struct list_head *list;

        if (hwports < 1)
                hwports = 1;
        else if (hwports > 8)
                hwports = 8;
        mcard->num_ports = hwports;

        if ((rval = snd_rawmidi_new(mcard->card, "MotuMIDI", 0,
                                    mcard->num_ports * 2 + MTPAV_PIDX_BROADCAST + 1,
                                    mcard->num_ports * 2 + MTPAV_PIDX_BROADCAST + 1,
                                    &mcard->rmidi)) < 0)
                return rval;
        rawmidi = mcard->rmidi;
        rawmidi->private_data = mcard;

        list_for_each(list, &rawmidi->streams[SNDRV_RAWMIDI_STREAM_INPUT].substreams) {
                substream = list_entry(list, struct snd_rawmidi_substream, list);
                snd_mtpav_set_name(mcard, substream);
                substream->ops = &snd_mtpav_input;
        }
        list_for_each(list, &rawmidi->streams[SNDRV_RAWMIDI_STREAM_OUTPUT].substreams) {
                substream = list_entry(list, struct snd_rawmidi_substream, list);
                snd_mtpav_set_name(mcard, substream);
                substream->ops = &snd_mtpav_output;
                mcard->ports[substream->number].hwport = translate_subdevice_to_hwport(mcard, substream->number);
        }
        rawmidi->info_flags |= SNDRV_RAWMIDI_INFO_OUTPUT | SNDRV_RAWMIDI_INFO_INPUT |
                               SNDRV_RAWMIDI_INFO_DUPLEX;
        sprintf(rawmidi->name, "MTP AV MIDI");
        return 0;
}

/*
 */

static void snd_mtpav_free(struct snd_card *card)
{
        struct mtpav *crd = card->private_data;
        unsigned long flags;

        spin_lock_irqsave(&crd->spinlock, flags);
        if (crd->istimer > 0)
                snd_mtpav_remove_output_timer(crd);
        spin_unlock_irqrestore(&crd->spinlock, flags);
        if (crd->irq >= 0)
                free_irq(crd->irq, (void *)crd);
        release_and_free_resource(crd->res_port);
}

/*
 */
static int snd_mtpav_probe(struct platform_device *dev)
{
        struct snd_card *card;
        int err;
        struct mtpav *mtp_card;

        err = snd_card_new(&dev->dev, index, id, THIS_MODULE,
                           sizeof(*mtp_card), &card);
        if (err < 0)
                return err;

        mtp_card = card->private_data;
        spin_lock_init(&mtp_card->spinlock);
        mtp_card->card = card;
        mtp_card->irq = -1;
        mtp_card->share_irq = 0;
        mtp_card->inmidistate = 0;
        mtp_card->outmidihwport = 0xffffffff;
        timer_setup(&mtp_card->timer, snd_mtpav_output_timer, 0);

        card->private_free = snd_mtpav_free;

        err = snd_mtpav_get_RAWMIDI(mtp_card);
        if (err < 0)
                goto __error;

        mtp_card->inmidiport = mtp_card->num_ports + MTPAV_PIDX_BROADCAST;

        err = snd_mtpav_get_ISA(mtp_card);
        if (err < 0)
                goto __error;

        strcpy(card->driver, "MTPAV");
        strcpy(card->shortname, "MTPAV on parallel port");
        snprintf(card->longname, sizeof(card->longname),
                 "MTPAV on parallel port at 0x%lx", port);

        snd_mtpav_portscan(mtp_card);

        err = snd_card_register(mtp_card->card);
        if (err < 0)
                goto __error;

        platform_set_drvdata(dev, card);
        printk(KERN_INFO "Motu MidiTimePiece on parallel port irq: %d ioport: 0x%lx\n", irq, port);
        return 0;

 __error:
        snd_card_free(card);
        return err;
}

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

#define SND_MTPAV_DRIVER        "snd_mtpav"

static struct platform_driver snd_mtpav_driver = {
        .probe          = snd_mtpav_probe,
        .remove         = snd_mtpav_remove,
        .driver         = {
                .name   = SND_MTPAV_DRIVER,
        },
};

static int __init alsa_card_mtpav_init(void)
{
        int err;

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

        device = platform_device_register_simple(SND_MTPAV_DRIVER, -1, NULL, 0);
        if (!IS_ERR(device)) {
                if (platform_get_drvdata(device))
                        return 0;
                platform_device_unregister(device);
                err = -ENODEV;
        } else
                err = PTR_ERR(device);
        platform_driver_unregister(&snd_mtpav_driver);
        return err;
}

static void __exit alsa_card_mtpav_exit(void)
{
        platform_device_unregister(device);
        platform_driver_unregister(&snd_mtpav_driver);
}

module_init(alsa_card_mtpav_init)
module_exit(alsa_card_mtpav_exit)