usb: dwc3: gadget: implement ->udc_set_speed()

Use this method to make sure we don't try to connect on speeds not
supported by the gadget driver.
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

drivers/usb/dwc3/gadget.c

@@ -1827,49 +1827,6 @@ static int __dwc3_gadget_start(struct dwc3 *dwc)
 		dwc3_writel(dwc->regs, DWC3_DEV_IMOD(0), 0);
 	}
 
-	reg = dwc3_readl(dwc->regs, DWC3_DCFG);
-	reg &= ~(DWC3_DCFG_SPEED_MASK);
-
-	/*
-	 * WORKAROUND: DWC3 revision < 2.20a have an issue
-	 * which would cause metastability state on Run/Stop
-	 * bit if we try to force the IP to USB2-only mode.
-	 *
-	 * Because of that, we cannot configure the IP to any
-	 * speed other than the SuperSpeed
-	 *
-	 * Refers to:
-	 *
-	 * STAR#9000525659: Clock Domain Crossing on DCTL in
-	 * USB 2.0 Mode
-	 */
-	if (dwc->revision < DWC3_REVISION_220A) {
-		reg |= DWC3_DCFG_SUPERSPEED;
-	} else {
-		switch (dwc->maximum_speed) {
-		case USB_SPEED_LOW:
-			reg |= DWC3_DCFG_LOWSPEED;
-			break;
-		case USB_SPEED_FULL:
-			reg |= DWC3_DCFG_FULLSPEED;
-			break;
-		case USB_SPEED_HIGH:
-			reg |= DWC3_DCFG_HIGHSPEED;
-			break;
-		case USB_SPEED_SUPER_PLUS:
-			reg |= DWC3_DCFG_SUPERSPEED_PLUS;
-			break;
-		default:
-			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);
-
 	/*
 	 * We are telling dwc3 that we want to use DCFG.NUMP as ACK TP's NUMP
 	 * field instead of letting dwc3 itself calculate that automatically.
@@ -2001,6 +1958,63 @@ static int dwc3_gadget_stop(struct usb_gadget *g)
 	return 0;
 }
 
+static void dwc3_gadget_set_speed(struct usb_gadget *g,
+				  enum usb_device_speed speed)
+{
+	struct dwc3		*dwc = gadget_to_dwc(g);
+	unsigned long		flags;
+	u32			reg;
+
+	spin_lock_irqsave(&dwc->lock, flags);
+	reg = dwc3_readl(dwc->regs, DWC3_DCFG);
+	reg &= ~(DWC3_DCFG_SPEED_MASK);
+
+	/*
+	 * WORKAROUND: DWC3 revision < 2.20a have an issue
+	 * which would cause metastability state on Run/Stop
+	 * bit if we try to force the IP to USB2-only mode.
+	 *
+	 * Because of that, we cannot configure the IP to any
+	 * speed other than the SuperSpeed
+	 *
+	 * Refers to:
+	 *
+	 * STAR#9000525659: Clock Domain Crossing on DCTL in
+	 * USB 2.0 Mode
+	 */
+	if (dwc->revision < DWC3_REVISION_220A) {
+		reg |= DWC3_DCFG_SUPERSPEED;
+	} else {
+		switch (speed) {
+		case USB_SPEED_LOW:
+			reg |= DWC3_DCFG_LOWSPEED;
+			break;
+		case USB_SPEED_FULL:
+			reg |= DWC3_DCFG_FULLSPEED;
+			break;
+		case USB_SPEED_HIGH:
+			reg |= DWC3_DCFG_HIGHSPEED;
+			break;
+		case USB_SPEED_SUPER:
+			reg |= DWC3_DCFG_SUPERSPEED;
+			break;
+		case USB_SPEED_SUPER_PLUS:
+			reg |= DWC3_DCFG_SUPERSPEED_PLUS;
+			break;
+		default:
+			dev_err(dwc->dev, "invalid speed (%d)\n", speed);
+
+			if (dwc->revision & DWC3_REVISION_IS_DWC31)
+				reg |= DWC3_DCFG_SUPERSPEED_PLUS;
+			else
+				reg |= DWC3_DCFG_SUPERSPEED;
+		}
+	}
+	dwc3_writel(dwc->regs, DWC3_DCFG, reg);
+
+	spin_unlock_irqrestore(&dwc->lock, flags);
+}
+
 static const struct usb_gadget_ops dwc3_gadget_ops = {
 	.get_frame		= dwc3_gadget_get_frame,
 	.wakeup			= dwc3_gadget_wakeup,
@@ -2008,6 +2022,7 @@ static const struct usb_gadget_ops dwc3_gadget_ops = {
 	.pullup			= dwc3_gadget_pullup,
 	.udc_start		= dwc3_gadget_start,
 	.udc_stop		= dwc3_gadget_stop,
+	.udc_set_speed		= dwc3_gadget_set_speed,
 };
 
 /* -------------------------------------------------------------------------- */