usb: gadget: dummy_hcd: add support for USB_DT_BOS on rh

Without a reply for USB_DT_BOS the USB3 mode does not work since
448b6eb ("USB: Make sure to fetch the BOS desc for roothubs.).

Cc: stable@vger.kernel.org #v3.5
Signed-off-by: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/gadget/dummy_hcd.c

@@ -1916,6 +1916,27 @@ static int dummy_hub_status(struct usb_hcd *hcd, char *buf)
 	return retval;
 }
 
+/* usb 3.0 root hub device descriptor */
+struct {
+	struct usb_bos_descriptor bos;
+	struct usb_ss_cap_descriptor ss_cap;
+} __packed usb3_bos_desc = {
+
+	.bos = {
+		.bLength		= USB_DT_BOS_SIZE,
+		.bDescriptorType	= USB_DT_BOS,
+		.wTotalLength		= cpu_to_le16(sizeof(usb3_bos_desc)),
+		.bNumDeviceCaps		= 1,
+	},
+	.ss_cap = {
+		.bLength		= USB_DT_USB_SS_CAP_SIZE,
+		.bDescriptorType	= USB_DT_DEVICE_CAPABILITY,
+		.bDevCapabilityType	= USB_SS_CAP_TYPE,
+		.wSpeedSupported	= cpu_to_le16(USB_5GBPS_OPERATION),
+		.bFunctionalitySupport	= ilog2(USB_5GBPS_OPERATION),
+	},
+};
+
 static inline void
 ss_hub_descriptor(struct usb_hub_descriptor *desc)
 {
@@ -2006,6 +2027,18 @@ static int dummy_hub_control(
 		else
 			hub_descriptor((struct usb_hub_descriptor *) buf);
 		break;
+
+	case DeviceRequest | USB_REQ_GET_DESCRIPTOR:
+		if (hcd->speed != HCD_USB3)
+			goto error;
+
+		if ((wValue >> 8) != USB_DT_BOS)
+			goto error;
+
+		memcpy(buf, &usb3_bos_desc, sizeof(usb3_bos_desc));
+		retval = sizeof(usb3_bos_desc);
+		break;
+
 	case GetHubStatus:
 		*(__le32 *) buf = cpu_to_le32(0);
 		break;