[9front] [PATCH 4/5] nusb/audio: enumerate streams through control interface

[Michael Forney <mforney@mforney.org>]

USB audio 2.0 splits the sample rate control from the AudioStreaming
alternate settings to a clock entity connected to input/output
terminals associated with the AudioStreaming interfaces. So, in order
to pair endpoints with their corresponding clock, we must have a
better picture of the audio function topology.

The AudioControl interface tells us which streams are available, so we
can go through each one, determining the possible stream parameters
and locating the associated endpoint. This will give us the necessary
context to locate the corresponding terminal (and soon, clock). When
we go to setup input/output endpoints, we now only have to consider
those that we have selected earlier.
---
 sys/src/cmd/nusb/audio/audio.c | 193 ++++++++++++++++++++++++---------
 1 file changed, 139 insertions(+), 54 deletions(-)

diff --git a/sys/src/cmd/nusb/audio/audio.c b/sys/src/cmd/nusb/audio/audio.c
index 09b84b8c48..2cd75f6361 100644
--- a/sys/src/cmd/nusb/audio/audio.c
+++ b/sys/src/cmd/nusb/audio/audio.c
@@ -19,16 +19,21 @@ enum {
 typedef struct Range Range;
 struct Range
 {
-	Range	*next;
-	int	min;
-	int	max;
+	uint	min;
+	uint	max;
 };
 
 typedef struct Aconf Aconf;
 struct Aconf
 {
+	Ep	*ep;
+	int	bits;
+	int	bps;	/* subslot size (bytes per sample) */
+	int	format;
+	int	channels;
+	int	controls;
 	Range	*freq;
-	int	caps;
+	int	nfreq;
 };
 
 int audiodelay = 1764;	/* 40 ms */
@@ -39,62 +44,131 @@ int audiores = 16;
 char user[] = "audio";
 
 Dev *audiodev = nil;
-
+Iface *audiocontrol = nil;
 Ep *audioepin = nil;
 Ep *audioepout = nil;
 
-void
-parsedescr(Desc *dd)
+Iface*
+findiface(Conf *conf, int class, int subclass, int id)
 {
-	Aconf *c;
-	Range *f;
-	uchar *b;
 	int i;
+	Iface *iface;
 
-	if(dd == nil || dd->iface == nil)
-		return;
-	if(Subclass(dd->iface->csp) != 2)
-		return;
+	for(i = 0; i < nelem(conf->iface); i++){
+		iface = conf->iface[i];
+		if(iface == nil || Class(iface->csp) != class || Subclass(iface->csp) != subclass)
+			continue;
+		if(id == -1 || iface->id == id)
+			return iface;
+	}
+	return nil;
+}
+
+Desc*
+findacheader(Usbdev *u, Iface *ac)
+{
+	Desc *dd;
+	uchar *b;
+	int i;
 
-	c = dd->iface->aux;
-	if(c == nil){
-		c = mallocz(sizeof(*c), 1);
-		dd->iface->aux = c;
+	for(i = 0; i < nelem(u->ddesc); i++){
+		dd = u->ddesc[i];
+		if(dd == nil || dd->iface != ac || dd->data.bDescriptorType != 0x24)
+			continue;
+		if(dd->data.bLength < 8 || dd->data.bbytes[0] != 1)
+			continue;
+		b = dd->data.bbytes;
+		if(dd->data.bLength == 8+b[5])
+			return dd;
 	}
+	return nil;
+}
+
+void
+parseasdesc(Desc *dd, Aconf *c)
+{
+	uchar *b;
+	Range *f;
 
-	b = (uchar*)&dd->data;
-	switch(b[1]<<8 | b[2]){
+	b = dd->data.bbytes;
+	switch(dd->data.bDescriptorType<<8 | b[0]){
 	case 0x2501:	/* CS_ENDPOINT, EP_GENERAL */
-		c->caps |= b[3];
+		if(dd->data.bLength != 7)
+			return;
+		c->controls = b[1];
 		break;
 
-	case 0x2402:	/* CS_INTERFACE, FORMAT_TYPE */
-		if(b[4] != audiochan)
-			break;
-		if(b[6] != audiores)
-			break;
+	case 0x2401:	/* CS_INTERFACE, AS_GENERAL */
+		if(dd->data.bLength != 7)
+			return;
+		c->format = GET2(&b[3]);
+		break;
 
-		if(b[7] == 0){
-			f = mallocz(sizeof(*f), 1);
-			f->min = b[8] | b[9]<<8 | b[10]<<16;
-			f->max = b[11] | b[12]<<8 | b[13]<<16;
-
-			f->next = c->freq;
-			c->freq = f;
-		} else {
-			for(i=0; i<b[7]; i++){
-				f = mallocz(sizeof(*f), 1);
-				f->min = b[8+3*i] | b[9+3*i]<<8 | b[10+3*i]<<16;
+	case 0x2402:	/* CS_INTERFACE, FORMAT_TYPE */
+		if(dd->data.bLength < 8 || b[1] != 1)
+			return;
+		c->channels = b[2];
+		c->bps = b[3];
+		c->bits = b[4];
+		if(b[5] == 0){	/* continuous frequency range */
+			c->nfreq = 1;
+			c->freq = emallocz(sizeof(*f), 1);
+			c->freq->min = b[6] | b[7]<<8 | b[8]<<16;
+			c->freq->max = b[9] | b[10]<<8 | b[11]<<16;
+		}else{		/* discrete sampling frequencies */
+			c->nfreq = b[5];
+			c->freq = emallocz(c->nfreq * sizeof(*f), 1);
+			b += 6;
+			for(f = c->freq; f < c->freq+c->nfreq; f++, b += 3){
+				f->min = b[0] | b[1]<<8 | b[2]<<16;
 				f->max = f->min;
-
-				f->next = c->freq;
-				c->freq = f;
 			}
 		}
 		break;
 	}
 }
 
+void
+parsestream(Dev *d, int id)
+{
+	Iface *as;
+	Desc *dd;
+	Ep *e;
+	Aconf *c;
+	int i;
+
+	/* find AS interface */
+	as = findiface(d->usb->conf[0], Claudio, 2, id);
+
+	/* enumerate through alt. settings */
+	for(; as != nil; as = as->next){
+		c = emallocz(sizeof(*c), 1);
+		as->aux = c;
+
+		/* find AS endpoint */
+		for(i = 0; i < nelem(as->ep); i++){
+			e = as->ep[i];
+			if(e != nil && e->type == Eiso && (e->attrib>>4 & 3) == Edata){
+				c->ep = e;
+				break;
+			}
+		}
+		if(c->ep == nil){
+			free(c);
+			as->aux = nil;
+			continue;
+		}
+
+		/* parse AS descriptors */
+		for(i = 0; i < nelem(d->usb->ddesc); i++){
+			dd = d->usb->ddesc[i];
+			if(dd == nil || dd->iface != as)
+				continue;
+			parseasdesc(dd, c);
+		}
+	}
+}
+
 Dev*
 setupep(Dev *d, Ep *e, int speed)
 {
@@ -103,12 +177,12 @@ setupep(Dev *d, Ep *e, int speed)
 	Range *f;
 
 	for(;e != nil; e = e->next){
-		if(e->dir!=dir)
-			continue;
 		c = e->iface->aux;
-		if(c == nil)
+		if(c == nil || e != c->ep || e->dir != dir)
 			continue;
-		for(f = c->freq; f != nil; f = f->next)
+		if(c->format != 1 || c->bits != audiores || 8*c->bps != audiores || c->channels != audiochan)
+			continue;
+		for(f = c->freq; f != c->freq+c->nfreq; f++)
 			if(speed >= f->min && speed <= f->max)
 				goto Foundaltc;
 	}
@@ -119,7 +193,7 @@ Foundaltc:
 	if(setalt(d, e->iface) < 0)
 		return nil;
 
-	if(c->caps & 1){
+	if(c->controls & 1){
 		uchar b[4];
 
 		b[0] = speed;
@@ -207,6 +281,10 @@ main(int argc, char *argv[])
 {
 	char buf[32];
 	Dev *d, *ed;
+	Desc *dd;
+	Conf *conf;
+	Iface *ac;
+	Aconf *c;
 	Ep *e;
 	int i;
 
@@ -226,15 +304,22 @@ main(int argc, char *argv[])
 		sysfatal("getdev: %r");
 	audiodev = d;
 
-	/* parse descriptors, mark valid altc */
-	for(i = 0; i < nelem(d->usb->ddesc); i++)
-		parsedescr(d->usb->ddesc[i]);
+	conf = d->usb->conf[0];
+	ac = findiface(conf, Claudio, 1, -1);
+	if(ac == nil)
+		sysfatal("no audio control interface");
+	audiocontrol = ac;
+
+	dd = findacheader(d->usb, ac);
+	if(dd == nil)
+		sysfatal("no audio control header");
+	for(i = 6; i < dd->data.bLength-2; i++)
+		parsestream(d, dd->data.bbytes[i]);
+
 	for(i = 0; i < nelem(d->usb->ep); i++){
-		e = d->usb->ep[i];
-		if(e == nil || e->type != Eiso || e->iface->csp != CSP(Claudio, 2, 0))
-			continue;
-		for(; e != nil; e = e->next){
-			if((e->attrib>>4 & 3) == Edata)
+		for(e = d->usb->ep[i]; e != nil; e = e->next){
+			c = e->iface->aux;
+			if(c != nil && c->ep == e)
 				break;
 		}
 		if(e == nil)
@@ -263,7 +348,7 @@ main(int argc, char *argv[])
 		closedev(ed);
 	}
 	if(audioepout == nil)
-		sysfatal("no endpoints found");
+		sysfatal("no output stream found");
 
 	fs.tree = alloctree(user, "usb", DMDIR|0555, nil);
 	createfile(fs.tree->root, "volume", user, 0666, nil);
-- 
2.37.3