usb: Parse the new USB 3.1 SuperSpeedPlus Isoc endpoint companion descriptor

USB 3.1 devices can return a new SuperSpeedPlus isoc endpoint companion
descriptor for a isochronous endpoint that requires more than 48K bytes
per Service Interval.

The new descriptor immediately follows the old USB 3.0 SuperSpeed Endpoint
Companion and will provide a new BytesPerInterval value.

It is parsed and stored in struct usb_host_endpoint with the other endpoint
related descriptors, and should be used by USB3.1 capable hosts to reserve
bus time in the schedule.

Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/core/config.c

@@ -43,6 +43,27 @@ static int find_next_descriptor(unsigned char *buffer, int size,
 	return buffer - buffer0;
 }
 
+static void usb_parse_ssp_isoc_endpoint_companion(struct device *ddev,
+		int cfgno, int inum, int asnum, struct usb_host_endpoint *ep,
+		unsigned char *buffer, int size)
+{
+	struct usb_ssp_isoc_ep_comp_descriptor *desc;
+
+	/*
+	 * The SuperSpeedPlus Isoc endpoint companion descriptor immediately
+	 * follows the SuperSpeed Endpoint Companion descriptor
+	 */
+	desc = (struct usb_ssp_isoc_ep_comp_descriptor *) buffer;
+	if (desc->bDescriptorType != USB_DT_SSP_ISOC_ENDPOINT_COMP ||
+	    size < USB_DT_SSP_ISOC_EP_COMP_SIZE) {
+		dev_warn(ddev, "Invalid SuperSpeedPlus isoc endpoint companion"
+			 "for config %d interface %d altsetting %d ep %d.\n",
+			 cfgno, inum, asnum, ep->desc.bEndpointAddress);
+		return;
+	}
+	memcpy(&ep->ssp_isoc_ep_comp, desc, USB_DT_SSP_ISOC_EP_COMP_SIZE);
+}
+
 static void usb_parse_ss_endpoint_companion(struct device *ddev, int cfgno,
 		int inum, int asnum, struct usb_host_endpoint *ep,
 		unsigned char *buffer, int size)
@@ -54,6 +75,9 @@ static void usb_parse_ss_endpoint_companion(struct device *ddev, int cfgno,
 	 * be the first thing immediately following the endpoint descriptor.
 	 */
 	desc = (struct usb_ss_ep_comp_descriptor *) buffer;
+	buffer += desc->bLength;
+	size -= desc->bLength;
+
 	if (desc->bDescriptorType != USB_DT_SS_ENDPOINT_COMP ||
 			size < USB_DT_SS_EP_COMP_SIZE) {
 		dev_warn(ddev, "No SuperSpeed endpoint companion for config %d "
@@ -112,6 +136,7 @@ static void usb_parse_ss_endpoint_companion(struct device *ddev, int cfgno,
 				cfgno, inum, asnum, ep->desc.bEndpointAddress);
 		ep->ss_ep_comp.bmAttributes = 16;
 	} else if (usb_endpoint_xfer_isoc(&ep->desc) &&
+		   !USB_SS_SSP_ISOC_COMP(desc->bmAttributes) &&
 		   USB_SS_MULT(desc->bmAttributes) > 3) {
 		dev_warn(ddev, "Isoc endpoint has Mult of %d in "
 				"config %d interface %d altsetting %d ep %d: "
@@ -121,6 +146,12 @@ static void usb_parse_ss_endpoint_companion(struct device *ddev, int cfgno,
 		ep->ss_ep_comp.bmAttributes = 2;
 	}
 
+	/* Parse a possible SuperSpeedPlus isoc ep companion descriptor */
+	if (usb_endpoint_xfer_isoc(&ep->desc) &&
+	    USB_SS_SSP_ISOC_COMP(desc->bmAttributes))
+		usb_parse_ssp_isoc_endpoint_companion(ddev, cfgno, inum, asnum,
+							ep, buffer, size);
+
 	if (usb_endpoint_xfer_isoc(&ep->desc))
 		max_tx = (desc->bMaxBurst + 1) *
 			(USB_SS_MULT(desc->bmAttributes)) *

include/linux/usb.h

@@ -50,6 +50,7 @@ struct ep_device;
  * struct usb_host_endpoint - host-side endpoint descriptor and queue
  * @desc: descriptor for this endpoint, wMaxPacketSize in native byteorder
  * @ss_ep_comp: SuperSpeed companion descriptor for this endpoint
+ * @ssp_isoc_ep_comp: SuperSpeedPlus isoc companion descriptor for this endpoint
  * @urb_list: urbs queued to this endpoint; maintained by usbcore
  * @hcpriv: for use by HCD; typically holds hardware dma queue head (QH)
  *	with one or more transfer descriptors (TDs) per urb
@@ -65,6 +66,7 @@ struct ep_device;
 struct usb_host_endpoint {
 	struct usb_endpoint_descriptor		desc;
 	struct usb_ss_ep_comp_descriptor	ss_ep_comp;
+	struct usb_ssp_isoc_ep_comp_descriptor	ssp_isoc_ep_comp;
 	struct list_head		urb_list;
 	void				*hcpriv;
 	struct ep_device		*ep_dev;	/* For sysfs info */