beginnings of virtual playback channel support

instead of using two malloced arrays for storing channel lists, use an
slist.  convert the sndstat device to use sbufs and optionally provide more
detail about channel state.

vchans are software mixed playback channels.  they are not enabled by this
commit.  they use the feeder infrastructure to emulate normal playback
channels in a manner transparent to applications, whilst providing as many
channels are desired, especially suitable for devices with only one hardware
playback channel.  in the future they will provide additional features.

those wishing to test this functionality will need to add vchan.c to
sys/conf/files and use 'sysctl -w hw.snd.pcm0.vchans' to enable it.

blocksize and auto-rate selection are not yet supported.

1 files changed, 113 insertions, 22 deletions

diff --git a/sys/dev/sound/pcm/channel.c b/sys/dev/sound/pcm/channel.c
index 8eec52832d09..727c509b805a 100644
--- a/sys/dev/sound/pcm/channel.c
+++ b/sys/dev/sound/pcm/channel.c
@@ -121,6 +121,7 @@ chn_dmaupdate(struct pcm_channel *c)
 	struct snd_dbuf *b = c->bufhard;
 	unsigned int delta, old, hwptr, amt;
 
+	KASSERT(sndbuf_getsize(b) > 0, ("bufsize == 0"));
 	CHN_LOCKASSERT(c);
 	old = sndbuf_gethwptr(b);
 	hwptr = chn_getptr(c);
@@ -130,7 +131,7 @@ chn_dmaupdate(struct pcm_channel *c)
 	DEB(
 	if (delta >= ((sndbuf_getsize(b) * 15) / 16)) {
 		if (!(c->flags & (CHN_F_CLOSING | CHN_F_ABORTING)))
-			device_printf(c->parent->dev, "hwptr went backwards %d -> %d\n", old, hwptr);
+			device_printf(c->parentsnddev->dev, "hwptr went backwards %d -> %d\n", old, hwptr);
 	}
 	);
 
@@ -231,13 +232,13 @@ chn_write(struct pcm_channel *c, struct uio *buf)
 	 * the write operation avoids blocking.
 	 */
 	if ((c->flags & CHN_F_NBIO) && buf->uio_resid > sndbuf_getblksz(bs)) {
-		DEB(device_printf(c->parent->dev, "broken app, nbio and tried to write %d bytes with fragsz %d\n",
+		DEB(device_printf(c->parentsnddev->dev, "broken app, nbio and tried to write %d bytes with fragsz %d\n",
 			buf->uio_resid, sndbuf_getblksz(bs)));
 		newsize = 16;
 		while (newsize < min(buf->uio_resid, CHN_2NDBUFMAXSIZE / 2))
 			newsize <<= 1;
 		chn_setblocksize(c, sndbuf_getblkcnt(bs), newsize);
-		DEB(device_printf(c->parent->dev, "frags reset to %d x %d\n", sndbuf_getblkcnt(bs), sndbuf_getblksz(bs)));
+		DEB(device_printf(c->parentsnddev->dev, "frags reset to %d x %d\n", sndbuf_getblkcnt(bs), sndbuf_getblksz(bs)));
 	}
 
 	ret = 0;
@@ -271,7 +272,7 @@ chn_write(struct pcm_channel *c, struct uio *buf)
 
 	if (count <= 0) {
 		c->flags |= CHN_F_DEAD;
-		device_printf(c->parent->dev, "play interrupt timeout, channel dead\n");
+		device_printf(c->parentsnddev->dev, "play interrupt timeout, channel dead\n");
 	}
 
 	return ret;
@@ -391,7 +392,7 @@ chn_read(struct pcm_channel *c, struct uio *buf)
 
 	if (count <= 0) {
 		c->flags |= CHN_F_DEAD;
-		device_printf(c->parent->dev, "record interrupt timeout, channel dead\n");
+		device_printf(c->parentsnddev->dev, "record interrupt timeout, channel dead\n");
 	}
 
 	return ret;
@@ -423,8 +424,19 @@ chn_start(struct pcm_channel *c, int force)
 	i = (c->direction == PCMDIR_PLAY)? sndbuf_getready(bs) : sndbuf_getfree(bs);
 	if (force || (i >= sndbuf_getblksz(b))) {
 		c->flags |= CHN_F_TRIGGERED;
-		if (c->direction == PCMDIR_PLAY)
-			chn_wrfeed(c);
+		/*
+		 * if we're starting because a vchan started, don't feed any data
+		 * or it becomes impossible to start vchans synchronised with the
+		 * first one.  the hardbuf should be empty so we top it up with
+		 * silence to give it something to chew.  the real data will be
+		 * fed at the first irq.
+		 */
+		if (c->direction == PCMDIR_PLAY) {
+			if (SLIST_EMPTY(&c->children))
+				chn_wrfeed(c);
+			else
+				sndbuf_fillsilence(b);
+		}
 		sndbuf_setrun(b, 1);
 	    	chn_trigger(c, PCMTRIG_START);
 		return 0;
@@ -458,7 +470,6 @@ chn_sync(struct pcm_channel *c, int threshold)
 
 	CHN_LOCKASSERT(c);
     	for (;;) {
-		chn_wrupdate(c);
 		rdy = (c->direction == PCMDIR_PLAY)? sndbuf_getfree(bs) : sndbuf_getready(bs);
 		if (rdy <= threshold) {
 	    		ret = chn_sleep(c, "pcmsyn", 1);
@@ -495,7 +506,7 @@ chn_poll(struct pcm_channel *c, int ev, struct proc *p)
  * chn_abort terminates a running dma transfer.  it may sleep up to 200ms.
  * it returns the number of bytes that have not been transferred.
  *
- * called from: dsp_close, dsp_ioctl, with both bufhards locked
+ * called from: dsp_close, dsp_ioctl, with channel locked
  */
 int
 chn_abort(struct pcm_channel *c)
@@ -509,7 +520,10 @@ chn_abort(struct pcm_channel *c)
 		return 0;
 	c->flags |= CHN_F_ABORTING;
 
-	/* wait up to 200ms for the secondary bufhard to empty */
+	/*
+	 * wait up to 200ms for the secondary buffer to empty-
+	 * a vchan will never have data in the secondary buffer so we won't sleep
+	 */
 	cnt = 10;
 	while ((sndbuf_getready(bs) > 0) && (cnt-- > 0)) {
 		chn_sleep(c, "pcmabr", hz / 50);
@@ -649,7 +663,7 @@ chn_init(struct pcm_channel *c, void *devinfo, int dir)
 		sndbuf_destroy(b);
 		return ENODEV;
 	}
-	if (sndbuf_getsize(b) == 0) {
+	if ((sndbuf_getsize(b) == 0) && ((c->flags & CHN_F_VIRTUAL) == 0)) {
 		sndbuf_destroy(bs);
 		sndbuf_destroy(b);
 		return ENOMEM;
@@ -714,6 +728,7 @@ chn_tryspeed(struct pcm_channel *c, int speed)
 	int r, delta;
 
 	CHN_LOCKASSERT(c);
+	DEB(printf("setspeed, channel %s\n", c->name));
 	DEB(printf("want speed %d, ", speed));
 	if (speed <= 0)
 		return EINVAL;
@@ -724,7 +739,7 @@ chn_tryspeed(struct pcm_channel *c, int speed)
 		RANGE(speed, chn_getcaps(c)->minspeed, chn_getcaps(c)->maxspeed);
 		DEB(printf("try speed %d, ", speed));
 		sndbuf_setspd(b, CHANNEL_SETSPEED(c->methods, c->devinfo, speed));
-		DEB(printf("got speed %d, ", sndbuf_getspd(b)));
+		DEB(printf("got speed %d\n", sndbuf_getspd(b)));
 
 		delta = sndbuf_getspd(b) - sndbuf_getspd(bs);
 		if (delta < 0)
@@ -762,6 +777,7 @@ chn_tryspeed(struct pcm_channel *c, int speed)
 		r = FEEDER_SET(f, FEEDRATE_DST, sndbuf_getspd(b));
 		DEB(printf("feeder_set(FEEDRATE_DST, %d) = %d\n", sndbuf_getspd(b), r));
 out:
+		DEB(printf("setspeed done, r = %d\n", r));
 		return r;
 	} else
 		return EINVAL;
@@ -957,17 +973,32 @@ chn_buildfeeder(struct pcm_channel *c)
 
 	c->align = sndbuf_getalign(c->bufsoft);
 
-	fc = feeder_getclass(NULL);
-	if (fc == NULL) {
-		DEB(printf("can't find root feeder\n"));
-		return EINVAL;
-	}
-	if (chn_addfeeder(c, fc, NULL)) {
-		DEB(printf("can't add root feeder\n"));
-		return EINVAL;
+	if (SLIST_EMPTY(&c->children)) {
+		fc = feeder_getclass(NULL);
+		if (fc == NULL) {
+			DEB(printf("can't find root feeder\n"));
+			return EINVAL;
+		}
+		if (chn_addfeeder(c, fc, NULL)) {
+			DEB(printf("can't add root feeder\n"));
+			return EINVAL;
+		}
+		c->feeder->desc->out = c->format;
+	} else {
+		desc.type = FEEDER_MIXER;
+		desc.in = 0;
+		desc.out = c->format;
+		desc.flags = 0;
+		fc = feeder_getclass(&desc);
+		if (fc == NULL) {
+			DEB(printf("can't find vchan feeder\n"));
+			return EINVAL;
+		}
+		if (chn_addfeeder(c, fc, &desc)) {
+			DEB(printf("can't add vchan feeder\n"));
+			return EINVAL;
+		}
 	}
-	c->feeder->desc->out = c->format;
-
 	flags = c->feederflags;
 
 	if ((c->flags & CHN_F_MAPPED) && (flags != 0)) {
@@ -1020,3 +1051,63 @@ chn_buildfeeder(struct pcm_channel *c)
 	return 0;
 }
 
+int
+chn_notify(struct pcm_channel *c, u_int32_t flags)
+{
+	struct pcmchan_children *pce;
+	struct pcm_channel *child;
+
+	if (SLIST_EMPTY(&c->children))
+		return ENODEV;
+
+	if (flags & CHN_N_RATE) {
+		/*
+		 * we could do something here, like scan children and decide on
+		 * the most appropriate rate to mix at, but we don't for now
+		 */
+	}
+	if (flags & CHN_N_FORMAT) {
+		/*
+		 * we could do something here, like scan children and decide on
+		 * the most appropriate mixer feeder to use, but we don't for now
+		 */
+	}
+	if (flags & CHN_N_VOLUME) {
+		/*
+		 * we could do something here but we don't for now
+		 */
+	}
+	if (flags & CHN_N_BLOCKSIZE) {
+		int blksz;
+		/*
+		 * scan the children, find the lowest blocksize and use that
+		 * for the hard blocksize
+		 */
+		blksz = sndbuf_getmaxsize(c->bufhard) / 2;
+		SLIST_FOREACH(pce, &c->children, link) {
+			child = pce->channel;
+			if (sndbuf_getblksz(child->bufhard) < blksz)
+				blksz = sndbuf_getblksz(child->bufhard);
+		}
+		chn_setblocksize(c, 2, blksz);
+	}
+	if (flags & CHN_N_TRIGGER) {
+		int run;
+		/*
+		 * scan the children, and figure out if any are running
+		 * if so, we need to be running, otherwise we need to be stopped
+		 * if we aren't in our target sstate, move to it
+		 */
+		run = 0;
+		SLIST_FOREACH(pce, &c->children, link) {
+			child = pce->channel;
+			if (child->flags & CHN_F_TRIGGERED)
+				run = 1;
+		}
+		if (run && !(c->flags & CHN_F_TRIGGERED))
+			chn_start(c, 1);
+		if (!run && (c->flags & CHN_F_TRIGGERED))
+			chn_abort(c);
+	}
+	return 0;
+}