xref: /freebsd/sys/dev/sound/pcm/sound.c (revision 66ef8af5b0e00b074572e81d3ff8c0453b284325)

/*
 * Copyright (c) 1999 Cameron Grant <gandalf@vilnya.demon.co.uk>
 * (C) 1997 Luigi Rizzo (luigi@iet.unipi.it)
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * $FreeBSD$
 */

#include <dev/sound/pcm/sound.h>
#include <sys/sysctl.h>

static dev_t 	status_dev = 0;
static int 	status_isopen = 0;
static int 	status_init(char *buf, int size);
static int 	status_read(struct uio *buf);

static d_open_t sndopen;
static d_close_t sndclose;
static d_ioctl_t sndioctl;
static d_read_t sndread;
static d_write_t sndwrite;
static d_mmap_t sndmmap;
static d_poll_t sndpoll;

#define CDEV_MAJOR 30
static struct cdevsw snd_cdevsw = {
	/* open */	sndopen,
	/* close */	sndclose,
	/* read */	sndread,
	/* write */	sndwrite,
	/* ioctl */	sndioctl,
	/* poll */	sndpoll,
	/* mmap */	sndmmap,
	/* strategy */	nostrategy,
	/* name */	"snd",
	/* maj */	CDEV_MAJOR,
	/* dump */	nodump,
	/* psize */	nopsize,
	/* flags */	D_TRACKCLOSE,
	/* bmaj */	-1
};

/*
PROPOSAL:
each unit needs:
status, mixer, dsp, dspW, audio, sequencer, midi-in, seq2, sndproc = 9 devices
dspW and audio are deprecated.
dsp needs min 64 channels, will give it 256

minor = (unit << 20) + (dev << 16) + channel
currently minor = (channel << 16) + (unit << 4) + dev

nomenclature:
	/dev/pcmX/dsp.(0..255)
	/dev/pcmX/dspW
	/dev/pcmX/audio
	/dev/pcmX/status
	/dev/pcmX/mixer
	[etc.]
*/

#define PCMMINOR(x) (minor(x))
#define PCMCHAN(x) ((PCMMINOR(x) & 0x00ff0000) >> 16)
#define PCMUNIT(x) ((PCMMINOR(x) & 0x000000f0) >> 4)
#define PCMDEV(x)   (PCMMINOR(x) & 0x0000000f)
#define PCMMKMINOR(u, d, c) ((((c) & 0xff) << 16) | (((u) & 0x0f) << 4) | ((d) & 0x0f))

static devclass_t pcm_devclass;

#ifdef USING_DEVFS
int snd_unit;
TUNABLE_INT_DECL("hw.snd.unit", 0, snd_unit);
#endif

SYSCTL_NODE(_hw, OID_AUTO, snd, CTLFLAG_RD, 0, "Sound driver");

void *
snd_mtxcreate(const char *desc)
{
#ifdef USING_MUTEX
	struct mtx *m;

	m = malloc(sizeof(*m), M_DEVBUF, M_WAITOK | M_ZERO);
	if (m == NULL)
		return NULL;
	mtx_init(m, desc, MTX_RECURSE);
	return m;
#else
	return (void *)0xcafebabe;
#endif
}

void
snd_mtxfree(void *m)
{
#ifdef USING_MUTEX
	struct mtx *mtx = m;

	mtx_assert(mtx, MA_OWNED);
	mtx_destroy(mtx);
	free(mtx, M_DEVBUF);
#endif
}

void
snd_mtxassert(void *m)
{
#ifdef USING_MUTEX
	struct mtx *mtx = m;

	mtx_assert(mtx, MA_OWNED);
#endif
}

void
snd_mtxlock(void *m)
{
#ifdef USING_MUTEX
	struct mtx *mtx = m;

	mtx_lock(mtx);
#endif
}

void
snd_mtxunlock(void *m)
{
#ifdef USING_MUTEX
	struct mtx *mtx = m;

	mtx_unlock(mtx);
#endif
}

int
snd_setup_intr(device_t dev, struct resource *res, int flags, driver_intr_t hand, void *param, void **cookiep)
{
#ifdef USING_MUTEX
	flags &= INTR_MPSAFE;
	flags |= INTR_TYPE_TTY;
#else
	flags = INTR_TYPE_TTY;
#endif
	return bus_setup_intr(dev, res, flags, hand, param, cookiep);
}

#ifdef USING_DEVFS
static void
pcm_makelinks(void *dummy)
{
	int unit;
	dev_t pdev;
	static dev_t dsp = 0, dspW = 0, audio = 0, mixer = 0;

	if (pcm_devclass == NULL || devfs_present == 0)
		return;
	if (dsp) {
		destroy_dev(dsp);
		dsp = 0;
	}
	if (dspW) {
		destroy_dev(dspW);
		dspW = 0;
	}
	if (audio) {
		destroy_dev(audio);
		audio = 0;
	}
	if (mixer) {
		destroy_dev(mixer);
		mixer = 0;
	}

	unit = snd_unit;
	if (unit < 0 || unit > devclass_get_maxunit(pcm_devclass))
		return;
	if (devclass_get_softc(pcm_devclass, unit) == NULL)
		return;

	pdev = makedev(CDEV_MAJOR, PCMMKMINOR(unit, SND_DEV_DSP, 0));
	dsp = make_dev_alias(pdev, "dsp");
	pdev = makedev(CDEV_MAJOR, PCMMKMINOR(unit, SND_DEV_DSP16, 0));
	dspW = make_dev_alias(pdev, "dspW");
	pdev = makedev(CDEV_MAJOR, PCMMKMINOR(unit, SND_DEV_AUDIO, 0));
	audio = make_dev_alias(pdev, "audio");
	pdev = makedev(CDEV_MAJOR, PCMMKMINOR(unit, SND_DEV_CTL, 0));
	mixer = make_dev_alias(pdev, "mixer");
}

static int
sysctl_hw_sndunit(SYSCTL_HANDLER_ARGS)
{
	int error, unit;

	unit = snd_unit;
	error = sysctl_handle_int(oidp, &unit, sizeof(unit), req);
	if (error == 0 && req->newptr != NULL) {
		snd_unit = unit;
		pcm_makelinks(NULL);
	}
	return (error);
}
SYSCTL_PROC(_hw_snd, OID_AUTO, unit, CTLTYPE_INT | CTLFLAG_RW,
            0, sizeof(int), sysctl_hw_sndunit, "I", "");
#endif

int
pcm_addchan(device_t dev, int dir, kobj_class_t cls, void *devinfo)
{
    	int unit = device_get_unit(dev), idx;
    	struct snddev_info *d = device_get_softc(dev);
	struct pcm_channel *chns, *ch;
	char *dirs;
	int err;

	dirs = ((dir == PCMDIR_PLAY)? "play" : "record");
	chns = ((dir == PCMDIR_PLAY)? d->play : d->rec);
	idx = ((dir == PCMDIR_PLAY)? d->playcount++ : d->reccount++);

	if (chns == NULL) {
		device_printf(dev, "bad channel add (%s:%d)\n", dirs, idx);
		return 1;
	}
	ch = &chns[idx];
	ch->methods = kobj_create(cls, M_DEVBUF, M_WAITOK);
	ch->parent = d;
	snprintf(ch->name, 32, "%s:%s:%d", device_get_nameunit(dev), dirs, idx);
	err = chn_init(ch, devinfo, dir);
	if (err) {
		device_printf(dev, "chn_init() for (%s:%d) failed: err = %d\n", dirs, idx, err);
		return 1;
	}
	make_dev(&snd_cdevsw, PCMMKMINOR(unit, SND_DEV_DSP, d->chancount),
		 UID_ROOT, GID_WHEEL, 0666, "dsp%d.%d", unit, d->chancount);
	make_dev(&snd_cdevsw, PCMMKMINOR(unit, SND_DEV_DSP16, d->chancount),
		 UID_ROOT, GID_WHEEL, 0666, "dspW%d.%d", unit, d->chancount);
	make_dev(&snd_cdevsw, PCMMKMINOR(unit, SND_DEV_AUDIO, d->chancount),
		 UID_ROOT, GID_WHEEL, 0666, "audio%d.%d", unit, d->chancount);
	/* XXX SND_DEV_NORESET? */
	d->chancount++;
#ifdef USING_DEVFS
    	if (d->chancount == 1)
		pcm_makelinks(NULL);
#endif
	return 0;
}

static int
pcm_killchan(device_t dev, int dir)
{
    	int unit = device_get_unit(dev), idx;
    	struct snddev_info *d = device_get_softc(dev);
	struct pcm_channel *chns, *ch;
	char *dirs;
	dev_t pdev;

	dirs = ((dir == PCMDIR_PLAY)? "play" : "record");
	chns = ((dir == PCMDIR_PLAY)? d->play : d->rec);
	idx = ((dir == PCMDIR_PLAY)? --d->playcount : --d->reccount);

	if (chns == NULL || idx < 0) {
		device_printf(dev, "bad channel kill (%s:%d)\n", dirs, idx);
		return 1;
	}
	ch = &chns[idx];
	if (chn_kill(ch)) {
		device_printf(dev, "chn_kill() for (%s:%d) failed\n", dirs, idx);
		return 1;
	}
	kobj_delete(ch->methods, M_DEVBUF);
	ch->methods = NULL;
	d->chancount--;
	pdev = makedev(CDEV_MAJOR, PCMMKMINOR(unit, SND_DEV_DSP, d->chancount));
	destroy_dev(pdev);
	pdev = makedev(CDEV_MAJOR, PCMMKMINOR(unit, SND_DEV_DSP16, d->chancount));
	destroy_dev(pdev);
	pdev = makedev(CDEV_MAJOR, PCMMKMINOR(unit, SND_DEV_AUDIO, d->chancount));
	destroy_dev(pdev);
	return 0;
}

int
pcm_setstatus(device_t dev, char *str)
{
    	struct snddev_info *d = device_get_softc(dev);
	strncpy(d->status, str, SND_STATUSLEN);
	return 0;
}

u_int32_t
pcm_getflags(device_t dev)
{
    	struct snddev_info *d = device_get_softc(dev);
	return d->flags;
}

void
pcm_setflags(device_t dev, u_int32_t val)
{
    	struct snddev_info *d = device_get_softc(dev);
	d->flags = val;
}

void *
pcm_getdevinfo(device_t dev)
{
    	struct snddev_info *d = device_get_softc(dev);
	return d->devinfo;
}

/* This is the generic init routine */
int
pcm_register(device_t dev, void *devinfo, int numplay, int numrec)
{
    	int sz, unit = device_get_unit(dev);
    	struct snddev_info *d = device_get_softc(dev);

    	if (!pcm_devclass) {
    		pcm_devclass = device_get_devclass(dev);
		status_dev = make_dev(&snd_cdevsw, PCMMKMINOR(0, SND_DEV_STATUS, 0),
			 UID_ROOT, GID_WHEEL, 0444, "sndstat");
	}
	make_dev(&snd_cdevsw, PCMMKMINOR(unit, SND_DEV_CTL, 0),
		 UID_ROOT, GID_WHEEL, 0666, "mixer%d", unit);
	d->dev = dev;
	d->devinfo = devinfo;
	d->chancount = d->playcount = d->reccount = 0;
	d->maxchans = numplay + numrec;
    	sz = (numplay + numrec) * sizeof(struct pcm_channel *);

	if (sz > 0) {
		d->aplay = (struct pcm_channel **)malloc(sz, M_DEVBUF, M_NOWAIT);
    		if (!d->aplay) goto no;
    		bzero(d->aplay, sz);

    		d->arec = (struct pcm_channel **)malloc(sz, M_DEVBUF, M_NOWAIT);
    		if (!d->arec) goto no;
    		bzero(d->arec, sz);

    		sz = (numplay + numrec) * sizeof(int);
		d->ref = (int *)malloc(sz, M_DEVBUF, M_NOWAIT);
    		if (!d->ref) goto no;
    		bzero(d->ref, sz);
	}

	if (numplay > 0) {
    		d->play = (struct pcm_channel *)malloc(numplay * sizeof(struct pcm_channel),
						M_DEVBUF, M_NOWAIT);
    		if (!d->play) goto no;
    		bzero(d->play, numplay * sizeof(struct pcm_channel));
	} else
		d->play = NULL;

	if (numrec > 0) {
	  	d->rec = (struct pcm_channel *)malloc(numrec * sizeof(struct pcm_channel),
				       	M_DEVBUF, M_NOWAIT);
    		if (!d->rec) goto no;
    		bzero(d->rec, numrec * sizeof(struct pcm_channel));
	} else
		d->rec = NULL;

#ifdef SND_DYNSYSCTL
	sysctl_ctx_init(&d->sysctl_tree);
	d->sysctl_tree_top = SYSCTL_ADD_NODE(&d->sysctl_tree,
				 SYSCTL_STATIC_CHILDREN(_hw_snd), OID_AUTO,
				 device_get_nameunit(dev), CTLFLAG_RD, 0, "");
	if (d->sysctl_tree_top == NULL) {
		sysctl_ctx_free(&d->sysctl_tree);
		goto no;
	}
#endif

	if (numplay == 0 || numrec == 0)
		d->flags |= SD_F_SIMPLEX;

	d->fakechan = fkchan_setup(dev);
	chn_init(d->fakechan, NULL, 0);

    	return 0;
no:
	if (d->aplay) free(d->aplay, M_DEVBUF);
	if (d->play) free(d->play, M_DEVBUF);
	if (d->arec) free(d->arec, M_DEVBUF);
	if (d->rec) free(d->rec, M_DEVBUF);
	if (d->ref) free(d->ref, M_DEVBUF);
	return ENXIO;
}

int
pcm_unregister(device_t dev)
{
    	int r, i, unit = device_get_unit(dev);
    	struct snddev_info *d = device_get_softc(dev);
	dev_t pdev;

	r = 0;
	for (i = 0; i < d->chancount; i++)
		if (d->ref[i]) r = EBUSY;
	if (r) {
		device_printf(dev, "unregister: channel busy");
		return r;
	}
	if (mixer_isbusy(d->mixer)) {
		device_printf(dev, "unregister: mixer busy");
		return EBUSY;
	}

#ifdef SND_DYNSYSCTL
	d->sysctl_tree_top = NULL;
	sysctl_ctx_free(&d->sysctl_tree);
#endif

	pdev = makedev(CDEV_MAJOR, PCMMKMINOR(unit, SND_DEV_CTL, 0));
	destroy_dev(pdev);
	mixer_uninit(dev);

	while (d->playcount > 0)
		pcm_killchan(dev, PCMDIR_PLAY);
	while (d->reccount > 0)
		pcm_killchan(dev, PCMDIR_REC);

	if (d->aplay) free(d->aplay, M_DEVBUF);
	if (d->play) free(d->play, M_DEVBUF);
	if (d->arec) free(d->arec, M_DEVBUF);
	if (d->rec) free(d->rec, M_DEVBUF);
	if (d->ref) free(d->ref, M_DEVBUF);

	chn_kill(d->fakechan);
	fkchan_kill(d->fakechan);

#ifdef USING_DEVFS
	pcm_makelinks(NULL);
#endif
	return 0;
}

/*
 * a small utility function which, given a device number, returns
 * a pointer to the associated struct snddev_info struct, and sets the unit
 * number.
 */
static struct snddev_info *
get_snddev_info(dev_t i_dev, int *unit, int *dev, int *chan)
{
	struct snddev_info *sc;
    	int u, d, c;

    	u = PCMUNIT(i_dev);
    	d = PCMDEV(i_dev);
    	c = PCMCHAN(i_dev);
    	if (u > devclass_get_maxunit(pcm_devclass)) u = -1;
    	if (unit) *unit = u;
    	if (dev) *dev = d;
    	if (chan) *chan = c;
    	if (u < 0) return NULL;

	sc = devclass_get_softc(pcm_devclass, u);
	if (sc == NULL) return NULL;

	switch(d) {
    	case SND_DEV_CTL:	/* /dev/mixer handled by pcm */
    	case SND_DEV_STATUS: /* /dev/sndstat handled by pcm */
    	case SND_DEV_DSP:
    	case SND_DEV_DSP16:
    	case SND_DEV_AUDIO:
		return sc;

    	case SND_DEV_SEQ: /* XXX when enabled... */
    	case SND_DEV_SEQ2:
    	case SND_DEV_MIDIN:
    	case SND_DEV_SNDPROC:	/* /dev/sndproc handled by pcm */
    	default:
		printf("unsupported subdevice %d\n", d);
		return NULL;
    	}
}

static int
sndopen(dev_t i_dev, int flags, int mode, struct proc *p)
{
    	int dev, unit, chan;
    	struct snddev_info *d = get_snddev_info(i_dev, &unit, &dev, &chan);

    	DEB(printf("open snd%d subdev %d flags 0x%08x mode 0x%08x\n",
		unit, dev, flags, mode));

    	switch(dev) {
    	case SND_DEV_STATUS:
		if (status_isopen) return EBUSY;
		status_isopen = 1;
		return 0;

    	case SND_DEV_CTL:
		return d? mixer_busy(d->mixer, 1) : ENXIO;

    	case SND_DEV_AUDIO:
    	case SND_DEV_DSP:
    	case SND_DEV_DSP16:
	case SND_DEV_NORESET:
		return d? dsp_open(d, chan, flags, dev) : ENXIO;

    	default:
    		return ENXIO;
    	}
}

static int
sndclose(dev_t i_dev, int flags, int mode, struct proc *p)
{
    	int dev, unit, chan;
    	struct snddev_info *d = get_snddev_info(i_dev, &unit, &dev, &chan);

    	DEB(printf("close snd%d subdev %d\n", unit, dev));

    	switch(dev) { /* only those for which close makes sense */
    	case SND_DEV_STATUS:
		if (!status_isopen) return EBADF;
		status_isopen = 0;
		return 0;

    	case SND_DEV_CTL:
		return d? mixer_busy(d->mixer, 0) : ENXIO;

    	case SND_DEV_AUDIO:
    	case SND_DEV_DSP:
    	case SND_DEV_DSP16:
		return d? dsp_close(d, chan, dev) : ENXIO;

    	default:
		return ENXIO;
    	}
}

static int
sndread(dev_t i_dev, struct uio *buf, int flag)
{
    	int dev, unit, chan;
    	struct snddev_info *d = get_snddev_info(i_dev, &unit, &dev, &chan);
    	DEB(printf("read snd%d subdev %d flag 0x%08x\n", unit, dev, flag));

    	switch(dev) {
    	case SND_DEV_STATUS:
		return status_isopen? status_read(buf) : EBADF;

    	case SND_DEV_AUDIO:
    	case SND_DEV_DSP:
    	case SND_DEV_DSP16:
        	return d? dsp_read(d, chan, buf, flag) : EBADF;

    	default:
    		return ENXIO;
    	}
}

static int
sndwrite(dev_t i_dev, struct uio *buf, int flag)
{
    	int dev, unit, chan;
    	struct snddev_info *d = get_snddev_info(i_dev, &unit, &dev, &chan);

    	DEB(printf("write snd%d subdev %d flag 0x%08x\n", unit, dev & 0xf, flag));

    	switch(dev) {	/* only writeable devices */
    	case SND_DEV_DSP:
    	case SND_DEV_DSP16:
    	case SND_DEV_AUDIO:
		return d? dsp_write(d, chan, buf, flag) : EBADF;

    	default:
		return EPERM; /* for non-writeable devices ; */
    	}
}

static int
sndioctl(dev_t i_dev, u_long cmd, caddr_t arg, int mode, struct proc * p)
{
    	int dev, chan;
    	struct snddev_info *d = get_snddev_info(i_dev, NULL, &dev, &chan);

    	if (d == NULL) return ENXIO;

    	switch(dev) {
    	case SND_DEV_CTL:
		return mixer_ioctl(d, cmd, arg);

    	case SND_DEV_AUDIO:
    	case SND_DEV_DSP:
    	case SND_DEV_DSP16:
		if (IOCGROUP(cmd) == 'M')
			return mixer_ioctl(d, cmd, arg);
		else
			return dsp_ioctl(d, chan, cmd, arg);

    	default:
    		return ENXIO;
    	}
}

static int
sndpoll(dev_t i_dev, int events, struct proc *p)
{
    	int dev, chan;
    	struct snddev_info *d = get_snddev_info(i_dev, NULL, &dev, &chan);

	DEB(printf("sndpoll d 0x%p dev 0x%04x events 0x%08x\n", d, dev, events));

    	if (d == NULL) return ENXIO;

    	switch(dev) {
    	case SND_DEV_AUDIO:
    	case SND_DEV_DSP:
    	case SND_DEV_DSP16:
		return dsp_poll(d, chan, events, p);

    	default:
    		return (events &
       		       (POLLIN | POLLOUT | POLLRDNORM | POLLWRNORM)) | POLLHUP;
    	}
}

/*
 * The mmap interface allows access to the play and read buffer,
 * plus the device descriptor.
 * The various blocks are accessible at the following offsets:
 *
 * 0x00000000 ( 0   ) : write buffer ;
 * 0x01000000 (16 MB) : read buffer ;
 * 0x02000000 (32 MB) : device descriptor (dangerous!)
 *
 * WARNING: the mmap routines assume memory areas are aligned. This
 * is true (probably) for the dma buffers, but likely false for the
 * device descriptor. As a consequence, we do not know where it is
 * located in the requested area.
 */
static int
sndmmap(dev_t i_dev, vm_offset_t offset, int nprot)
{
    	int unit, dev, chan;
    	struct snddev_info *d = get_snddev_info(i_dev, &unit, &dev, &chan);

    	DEB(printf("sndmmap d 0x%p dev 0x%04x ofs 0x%08x nprot 0x%08x\n",
		   d, dev, offset, nprot));

    	if (d == NULL || nprot & PROT_EXEC)	return -1; /* forbidden */

    	switch(dev) {
    	case SND_DEV_AUDIO:
    	case SND_DEV_DSP:
    	case SND_DEV_DSP16:
		return dsp_mmap(d, chan, offset, nprot);

    	default:
    		return -1;
    	}
}

static int
status_init(char *buf, int size)
{
    	int             i;
    	device_t	    dev;
    	struct snddev_info     *d;

    	snprintf(buf, size, "FreeBSD Audio Driver (newpcm) %s %s\n"
		 "Installed devices:\n", __DATE__, __TIME__);

    	for (i = 0; i <= devclass_get_maxunit(pcm_devclass); i++) {
		d = devclass_get_softc(pcm_devclass, i);
		if (!d) continue;
		dev = devclass_get_device(pcm_devclass, i);
        	if (1) {
			snprintf(buf + strlen(buf), size - strlen(buf),
		            	"pcm%d: <%s> %s",
		            	i, device_get_desc(dev), d->status);
			if (d->chancount > 0)
				snprintf(buf + strlen(buf), size - strlen(buf),
				" (%dp/%dr channels%s)\n",
			    	d->playcount, d->reccount,
			    	(!(d->flags & SD_F_SIMPLEX))? " duplex" : "");
			else
				snprintf(buf + strlen(buf), size - strlen(buf),
				" (mixer only)\n");
		}
    	}
    	return strlen(buf);
}

static int
status_read(struct uio *buf)
{
    	static char	status_buf[4096];
    	static int 	bufptr = 0, buflen = 0;
    	int l;

    	if (status_isopen == 1) {
		status_isopen++;
		bufptr = 0;
		buflen = status_init(status_buf, sizeof status_buf);
    	}

    	l = min(buf->uio_resid, buflen - bufptr);
    	bufptr += l;
    	return (l > 0)? uiomove(status_buf + bufptr - l, l, buf) : 0;
}

static int
sndpcm_modevent(module_t mod, int type, void *data)
{

	switch (type) {
	case MOD_LOAD:
		break;
	case MOD_UNLOAD:
		if (status_isopen)
			return EBUSY;
		if (status_dev)
			destroy_dev(status_dev);
		status_dev = 0;
		break;
	default:
		break;
	}
	return 0;
}

static moduledata_t sndpcm_mod = {
	"snd_pcm",
	sndpcm_modevent,
	NULL
};
DECLARE_MODULE(snd_pcm, sndpcm_mod, SI_SUB_DRIVERS, SI_ORDER_MIDDLE);
MODULE_VERSION(snd_pcm, PCM_MODVER);