USB: Parse and store the SuperSpeed endpoint companion descriptors.

The USB 3.0 bus specification added an "Endpoint Companion" descriptor that is
supposed to follow all SuperSpeed Endpoint descriptors.  This descriptor is used
to extend the bus protocol to allow more packets to be sent to an endpoint per
"microframe".  The word microframe was removed from the USB 3.0 specification
because the host controller does not send Start Of Frame (SOF) symbols down the
USB 3.0 wires.

The descriptor defines a bMaxBurst field, which indicates the number of packets
of wMaxPacketSize that a SuperSpeed device can send or recieve in a service
interval.  All non-control endpoints may set this value as high as 16 packets
(bMaxBurst = 15).

The descriptor also allows isochronous endpoints to further specify that they
can send and receive multiple bursts per service interval.  The bmAttributes
allows them to specify a "Mult" of up to 3 (bmAttributes = 2).

Bulk endpoints use bmAttributes to report the number of "Streams" they support.
This was an extension of the endpoint pipe concept to allow multiple mass
storage device commands to be outstanding for one bulk endpoint at a time.  This
should allow USB 3.0 mass storage devices to support SCSI command queueing.
Bulk endpoints can say they support up to 2^16 (65,536) streams.

The information in the endpoint companion descriptor must be stored with the
other device, config, interface, and endpoint descriptors because the host
controller needs to access them quickly, and we need to install some default
values if a SuperSpeed device doesn't provide an endpoint companion descriptor.

Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 180 insertions, 9 deletions

diff --git a/drivers/usb/core/config.c b/drivers/usb/core/config.c
index e9426acf568..7103758bb48 100644
--- a/drivers/usb/core/config.c
+++ b/drivers/usb/core/config.c
@@ -19,6 +19,32 @@ static inline const char *plural(int n)
 	return (n == 1 ? "" : "s");
 }
 
+/* FIXME: this is a kludge */
+static int find_next_descriptor_more(unsigned char *buffer, int size,
+    int dt1, int dt2, int dt3, int *num_skipped)
+{
+	struct usb_descriptor_header *h;
+	int n = 0;
+	unsigned char *buffer0 = buffer;
+
+	/* Find the next descriptor of type dt1 or dt2 or dt3 */
+	while (size > 0) {
+		h = (struct usb_descriptor_header *) buffer;
+		if (h->bDescriptorType == dt1 || h->bDescriptorType == dt2 ||
+				h->bDescriptorType == dt3)
+			break;
+		buffer += h->bLength;
+		size -= h->bLength;
+		++n;
+	}
+
+	/* Store the number of descriptors skipped and return the
+	 * number of bytes skipped */
+	if (num_skipped)
+		*num_skipped = n;
+	return buffer - buffer0;
+}
+
 static int find_next_descriptor(unsigned char *buffer, int size,
     int dt1, int dt2, int *num_skipped)
 {
@@ -43,6 +69,128 @@ static int find_next_descriptor(unsigned char *buffer, int size,
 	return buffer - buffer0;
 }
 
+static int usb_parse_endpoint_companion(struct device *ddev, int cfgno,
+		int inum, int asnum, struct usb_host_endpoint *ep,
+		int num_ep, unsigned char *buffer, int size)
+{
+	unsigned char *buffer_start = buffer;
+	struct usb_ep_comp_descriptor	*desc;
+	int retval;
+	int num_skipped;
+	int max_tx;
+	int i;
+
+	/* Allocate space for the companion descriptor */
+	ep->ep_comp = kzalloc(sizeof(struct usb_host_ep_comp), GFP_KERNEL);
+	if (!ep->ep_comp)
+		return -ENOMEM;
+	desc = (struct usb_ep_comp_descriptor *) buffer;
+	if (desc->bDescriptorType != USB_DT_SS_ENDPOINT_COMP) {
+		dev_warn(ddev, "No SuperSpeed endpoint companion for config %d "
+				" interface %d altsetting %d ep %d: "
+				"using minimum values\n",
+				cfgno, inum, asnum, ep->desc.bEndpointAddress);
+		ep->ep_comp->desc.bLength = USB_DT_EP_COMP_SIZE;
+		ep->ep_comp->desc.bDescriptorType = USB_DT_SS_ENDPOINT_COMP;
+		ep->ep_comp->desc.bMaxBurst = 0;
+		/*
+		 * Leave bmAttributes as zero, which will mean no streams for
+		 * bulk, and isoc won't support multiple bursts of packets.
+		 * With bursts of only one packet, and a Mult of 1, the max
+		 * amount of data moved per endpoint service interval is one
+		 * packet.
+		 */
+		if (usb_endpoint_xfer_isoc(&ep->desc) ||
+				usb_endpoint_xfer_int(&ep->desc))
+			ep->ep_comp->desc.wBytesPerInterval =
+				ep->desc.wMaxPacketSize;
+		/*
+		 * The next descriptor is for an Endpoint or Interface,
+		 * no extra descriptors to copy into the companion structure,
+		 * and we didn't eat up any of the buffer.
+		 */
+		retval = 0;
+		goto valid;
+	}
+	memcpy(&ep->ep_comp->desc, desc, USB_DT_EP_COMP_SIZE);
+	desc = &ep->ep_comp->desc;
+	buffer += desc->bLength;
+	size -= desc->bLength;
+
+	/* Eat up the other descriptors we don't care about */
+	ep->ep_comp->extra = buffer;
+	i = find_next_descriptor(buffer, size, USB_DT_ENDPOINT,
+			USB_DT_INTERFACE, &num_skipped);
+	ep->ep_comp->extralen = i;
+	buffer += i;
+	size -= i;
+	retval = buffer - buffer_start + i;
+	if (num_skipped > 0)
+		dev_dbg(ddev, "skipped %d descriptor%s after %s\n",
+				num_skipped, plural(num_skipped),
+				"SuperSpeed endpoint companion");
+
+	/* Check the various values */
+	if (usb_endpoint_xfer_control(&ep->desc) && desc->bMaxBurst != 0) {
+		dev_warn(ddev, "Control endpoint with bMaxBurst = %d in "
+				"config %d interface %d altsetting %d ep %d: "
+				"setting to zero\n", desc->bMaxBurst,
+				cfgno, inum, asnum, ep->desc.bEndpointAddress);
+		desc->bMaxBurst = 0;
+	}
+	if (desc->bMaxBurst > 15) {
+		dev_warn(ddev, "Endpoint with bMaxBurst = %d in "
+				"config %d interface %d altsetting %d ep %d: "
+				"setting to 15\n", desc->bMaxBurst,
+				cfgno, inum, asnum, ep->desc.bEndpointAddress);
+		desc->bMaxBurst = 15;
+	}
+	if ((usb_endpoint_xfer_control(&ep->desc) || usb_endpoint_xfer_int(&ep->desc))
+			&& desc->bmAttributes != 0) {
+		dev_warn(ddev, "%s endpoint with bmAttributes = %d in "
+				"config %d interface %d altsetting %d ep %d: "
+				"setting to zero\n",
+				usb_endpoint_xfer_control(&ep->desc) ? "Control" : "Bulk",
+				desc->bmAttributes,
+				cfgno, inum, asnum, ep->desc.bEndpointAddress);
+		desc->bmAttributes = 0;
+	}
+	if (usb_endpoint_xfer_bulk(&ep->desc) && desc->bmAttributes > 16) {
+		dev_warn(ddev, "Bulk endpoint with more than 65536 streams in "
+				"config %d interface %d altsetting %d ep %d: "
+				"setting to max\n",
+				cfgno, inum, asnum, ep->desc.bEndpointAddress);
+		desc->bmAttributes = 16;
+	}
+	if (usb_endpoint_xfer_isoc(&ep->desc) && desc->bmAttributes > 2) {
+		dev_warn(ddev, "Isoc endpoint has Mult of %d in "
+				"config %d interface %d altsetting %d ep %d: "
+				"setting to 3\n", desc->bmAttributes + 1,
+				cfgno, inum, asnum, ep->desc.bEndpointAddress);
+		desc->bmAttributes = 2;
+	}
+	if (usb_endpoint_xfer_isoc(&ep->desc)) {
+		max_tx = ep->desc.wMaxPacketSize * (desc->bMaxBurst + 1) *
+			(desc->bmAttributes + 1);
+	} else if (usb_endpoint_xfer_int(&ep->desc)) {
+		max_tx = ep->desc.wMaxPacketSize * (desc->bMaxBurst + 1);
+	} else {
+		goto valid;
+	}
+	if (desc->wBytesPerInterval > max_tx) {
+		dev_warn(ddev, "%s endpoint with wBytesPerInterval of %d in "
+				"config %d interface %d altsetting %d ep %d: "
+				"setting to %d\n",
+				usb_endpoint_xfer_isoc(&ep->desc) ? "Isoc" : "Int",
+				desc->wBytesPerInterval,
+				cfgno, inum, asnum, ep->desc.bEndpointAddress,
+				max_tx);
+		desc->wBytesPerInterval = max_tx;
+	}
+valid:
+	return retval;
+}
+
 static int usb_parse_endpoint(struct device *ddev, int cfgno, int inum,
     int asnum, struct usb_host_interface *ifp, int num_ep,
     unsigned char *buffer, int size)
@@ -50,7 +198,7 @@ static int usb_parse_endpoint(struct device *ddev, int cfgno, int inum,
 	unsigned char *buffer0 = buffer;
 	struct usb_endpoint_descriptor *d;
 	struct usb_host_endpoint *endpoint;
-	int n, i, j;
+	int n, i, j, retval;
 
 	d = (struct usb_endpoint_descriptor *) buffer;
 	buffer += d->bLength;
@@ -162,17 +310,38 @@ static int usb_parse_endpoint(struct device *ddev, int cfgno, int inum,
 				cfgno, inum, asnum, d->bEndpointAddress,
 				maxp);
 	}
-
-	/* Skip over any Class Specific or Vendor Specific descriptors;
-	 * find the next endpoint or interface descriptor */
-	endpoint->extra = buffer;
-	i = find_next_descriptor(buffer, size, USB_DT_ENDPOINT,
-	    USB_DT_INTERFACE, &n);
-	endpoint->extralen = i;
+	/* Allocate room for and parse any endpoint companion descriptors */
+	if (to_usb_device(ddev)->speed == USB_SPEED_SUPER) {
+		endpoint->extra = buffer;
+		i = find_next_descriptor_more(buffer, size, USB_DT_SS_ENDPOINT_COMP,
+				USB_DT_ENDPOINT, USB_DT_INTERFACE, &n);
+		endpoint->extralen = i;
+		buffer += i;
+		size -= i;
+
+		if (size > 0) {
+			retval = usb_parse_endpoint_companion(ddev, cfgno, inum, asnum,
+					endpoint, num_ep, buffer, size);
+			if (retval >= 0) {
+				buffer += retval;
+				retval = buffer - buffer0;
+			}
+		} else {
+			retval = buffer - buffer0;
+		}
+	} else {
+		/* Skip over any Class Specific or Vendor Specific descriptors;
+		 * find the next endpoint or interface descriptor */
+		endpoint->extra = buffer;
+		i = find_next_descriptor(buffer, size, USB_DT_ENDPOINT,
+				USB_DT_INTERFACE, &n);
+		endpoint->extralen = i;
+		retval = buffer - buffer0 + i;
+	}
 	if (n > 0)
 		dev_dbg(ddev, "skipped %d descriptor%s after %s\n",
 		    n, plural(n), "endpoint");
-	return buffer - buffer0 + i;
+	return retval;
 
 skip_to_next_endpoint_or_interface_descriptor:
 	i = find_next_descriptor(buffer, size, USB_DT_ENDPOINT,
@@ -453,6 +622,8 @@ static int usb_parse_configuration(struct device *ddev, int cfgidx,
 		kref_init(&intfc->ref);
 	}
 
+	/* FIXME: parse the BOS descriptor */
+
 	/* Skip over any Class Specific or Vendor Specific descriptors;
 	 * find the first interface descriptor */
 	config->extra = buffer;