usb: Add USB 3.1 Precision time measurement capability descriptor support

USB 3.1 devices that support precision time measurement have an
additional PTM cabaility descriptor as part of the full BOS descriptor

Look for this descriptor while parsing the BOS descriptor, and store it in
struct usb_hub_bos if it exists.
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/core/config.c

@@ -894,6 +894,9 @@ int usb_get_bos_descriptor(struct usb_device *dev)
 			dev->bos->ss_id =
 				(struct usb_ss_container_id_descriptor *)buffer;
 			break;
+		case USB_PTM_CAP_TYPE:
+			dev->bos->ptm_cap =
+				(struct usb_ptm_cap_descriptor *)buffer;
 		default:
 			break;
 		}

include/linux/usb.h

@@ -332,6 +332,7 @@ struct usb_host_bos {
 	struct usb_ss_cap_descriptor	*ss_cap;
 	struct usb_ssp_cap_descriptor	*ssp_cap;
 	struct usb_ss_container_id_descriptor	*ss_id;
+	struct usb_ptm_cap_descriptor	*ptm_cap;
 };
 
 int __usb_get_extra_descriptor(char *buffer, unsigned size,

include/uapi/linux/usb/ch9.h

@@ -912,6 +912,16 @@ struct usb_ssp_cap_descriptor {
 #define USB_SSP_SUBLINK_SPEED_LSM	(0xff << 16)	/* Lanespeed mantissa */
 } __attribute__((packed));
 
+/*
+ * Precision time measurement capability descriptor: advertised by devices and
+ * hubs that support PTM
+ */
+#define	USB_PTM_CAP_TYPE	0xb
+struct usb_ptm_cap_descriptor {
+	__u8  bLength;
+	__u8  bDescriptorType;
+	__u8  bDevCapabilityType;
+} __attribute__((packed));
 
 /*-------------------------------------------------------------------------*/