usb: dwc3: Validate the maximum_speed parameter

Check that dwc->maximum_speed is set to a valid value. Also add an error
when we use it later if we encounter an invalid value.

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

drivers/usb/dwc3/core.c

@@ -1012,8 +1012,20 @@ static int dwc3_probe(struct platform_device *pdev)
 		goto err1;
 	}
 
-	/* default to superspeed if no maximum_speed passed */
-	if (dwc->maximum_speed == USB_SPEED_UNKNOWN) {
+	/* Check the maximum_speed parameter */
+	switch (dwc->maximum_speed) {
+	case USB_SPEED_LOW:
+	case USB_SPEED_FULL:
+	case USB_SPEED_HIGH:
+	case USB_SPEED_SUPER:
+	case USB_SPEED_SUPER_PLUS:
+		break;
+	default:
+		dev_err(dev, "invalid maximum_speed parameter %d\n",
+			dwc->maximum_speed);
+		/* fall through */
+	case USB_SPEED_UNKNOWN:
+		/* default to superspeed */
 		dwc->maximum_speed = USB_SPEED_SUPER;
 
 		/*
@@ -1023,6 +1035,8 @@ static int dwc3_probe(struct platform_device *pdev)
 		    (DWC3_GHWPARAMS3_SSPHY_IFC(dwc->hwparams.hwparams3) ==
 		     DWC3_GHWPARAMS3_SSPHY_IFC_GEN2))
 			dwc->maximum_speed = USB_SPEED_SUPER_PLUS;
+
+		break;
 	}
 
 	/* Adjust Frame Length */

drivers/usb/dwc3/gadget.c

@@ -1670,10 +1670,13 @@ static int dwc3_gadget_start(struct usb_gadget *g,
 		case USB_SPEED_SUPER_PLUS:
 			reg |= DWC3_DSTS_SUPERSPEED_PLUS;
 			break;
-		case USB_SPEED_SUPER:	/* FALLTHROUGH */
-		case USB_SPEED_UNKNOWN:	/* FALTHROUGH */
 		default:
-			reg |= DWC3_DSTS_SUPERSPEED;
+			dev_err(dwc->dev, "invalid dwc->maximum_speed (%d)\n",
+				dwc->maximum_speed);
+			/* fall through */
+		case USB_SPEED_SUPER:
+			reg |= DWC3_DCFG_SUPERSPEED;
+			break;
 		}
 	}
 	dwc3_writel(dwc->regs, DWC3_DCFG, reg);