usb: gadget: mv_udc: refine suspend/resume function

This patch impletments system suspend/resume functions for Marvell
otg controller.
If OTG is enabled, OTG driver will do most of the work.
If not, we will check clock gating.
  If clock gating is enabled, the UDC will be start/stop automatically.
  If not, UDC will be start/stop in suspend/resume functions.
Signed-off-by: Neil Zhang <zhangwm@marvell.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/gadget/mv_udc_core.c

@@ -2447,7 +2447,30 @@ static int mv_udc_suspend(struct device *_dev)
 {
 	struct mv_udc *udc = the_controller;
 
-	udc_stop(udc);
+	/* if OTG is enabled, the following will be done in OTG driver*/
+	if (udc->transceiver)
+		return 0;
+
+	if (udc->pdata->vbus && udc->pdata->vbus->poll)
+		if (udc->pdata->vbus->poll() == VBUS_HIGH) {
+			dev_info(&udc->dev->dev, "USB cable is connected!\n");
+			return -EAGAIN;
+		}
+
+	/*
+	 * only cable is unplugged, udc can suspend.
+	 * So do not care about clock_gating == 1.
+	 */
+	if (!udc->clock_gating) {
+		udc_stop(udc);
+
+		spin_lock_irq(&udc->lock);
+		/* stop all usb activities */
+		stop_activity(udc, udc->driver);
+		spin_unlock_irq(&udc->lock);
+
+		mv_udc_disable_internal(udc);
+	}
 
 	return 0;
 }
@@ -2457,20 +2480,22 @@ static int mv_udc_resume(struct device *_dev)
 	struct mv_udc *udc = the_controller;
 	int retval;
 
-	if (udc->pdata->phy_init) {
-		retval = udc->pdata->phy_init(udc->phy_regs);
-		if (retval) {
-			dev_err(&udc->dev->dev,
-				"init phy error %d when resume back\n",
-				retval);
+	/* if OTG is enabled, the following will be done in OTG driver*/
+	if (udc->transceiver)
+		return 0;
+
+	if (!udc->clock_gating) {
+		retval = mv_udc_enable_internal(udc);
+		if (retval)
 			return retval;
+
+		if (udc->driver && udc->softconnect) {
+			udc_reset(udc);
+			ep0_reset(udc);
+			udc_start(udc);
 		}
 	}
 
-	udc_reset(udc);
-	ep0_reset(udc);
-	udc_start(udc);
-
 	return 0;
 }