usb: dwc3: Enable SuperSpeedPlus

Enable SuperSpeedPlus by programming the DCFG.speed and after
enumerating, set gadget->speed appropriately.

Signed-off-by: John Youn <johnyoun@synopsys.com>
Signed-off-by: Felipe Balbi <balbi@kernel.org>

drivers/usb/dwc3/gadget.c

@@ -1667,6 +1667,9 @@ static int dwc3_gadget_start(struct usb_gadget *g,
 		case USB_SPEED_HIGH:
 			reg |= DWC3_DSTS_HIGHSPEED;
 			break;
+		case USB_SPEED_SUPER_PLUS:
+			reg |= DWC3_DSTS_SUPERSPEED_PLUS;
+			break;
 		case USB_SPEED_SUPER:	/* FALLTHROUGH */
 		case USB_SPEED_UNKNOWN:	/* FALTHROUGH */
 		default:
@@ -2371,6 +2374,11 @@ static void dwc3_gadget_conndone_interrupt(struct dwc3 *dwc)
 	dwc3_update_ram_clk_sel(dwc, speed);
 
 	switch (speed) {
+	case DWC3_DCFG_SUPERSPEED_PLUS:
+		dwc3_gadget_ep0_desc.wMaxPacketSize = cpu_to_le16(512);
+		dwc->gadget.ep0->maxpacket = 512;
+		dwc->gadget.speed = USB_SPEED_SUPER_PLUS;
+		break;
 	case DWC3_DCFG_SUPERSPEED:
 		/*
 		 * WORKAROUND: DWC3 revisions <1.90a have an issue which