usb: dwc2: Update exit clock gating when port is resumed

Updates the implementation of exiting clock gating mode
when core receives port resume.
Instead of setting the required bit fields of the registers
inline, called the "dwc2_host_exit_clock_gating()" function.

Signed-off-by: Artur Petrosyan <Arthur.Petrosyan@synopsys.com>
Link: https://lore.kernel.org/r/20210413073701.367E0A022E@mailhost.synopsys.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/dwc2/hcd.c

@@ -3359,8 +3359,6 @@ int dwc2_port_suspend(struct dwc2_hsotg *hsotg, u16 windex)
 int dwc2_port_resume(struct dwc2_hsotg *hsotg)
 {
 	unsigned long flags;
-	u32 hprt0;
-	u32 pcgctl;
 	int ret = 0;
 
 	spin_lock_irqsave(&hsotg->lock, flags);
@@ -3374,33 +3372,14 @@ int dwc2_port_resume(struct dwc2_hsotg *hsotg)
 		break;
 	case DWC2_POWER_DOWN_PARAM_HIBERNATION:
 	case DWC2_POWER_DOWN_PARAM_NONE:
-	default:
 		/*
-		 * If power_down is supported, Phy clock is already resumed
-		 * after registers restore.
+		 * If not hibernation nor partial power down are supported,
+		 * port resume is done using the clock gating programming flow.
 		 */
-		if (!hsotg->params.power_down) {
-			pcgctl = dwc2_readl(hsotg, PCGCTL);
-			pcgctl &= ~PCGCTL_STOPPCLK;
-			dwc2_writel(hsotg, pcgctl, PCGCTL);
-			spin_unlock_irqrestore(&hsotg->lock, flags);
-			msleep(20);
-			spin_lock_irqsave(&hsotg->lock, flags);
-		}
-
-		hprt0 = dwc2_read_hprt0(hsotg);
-		hprt0 |= HPRT0_RES;
-		hprt0 &= ~HPRT0_SUSP;
-		dwc2_writel(hsotg, hprt0, HPRT0);
 		spin_unlock_irqrestore(&hsotg->lock, flags);
-
-		msleep(USB_RESUME_TIMEOUT);
-
+		dwc2_host_exit_clock_gating(hsotg, 0);
 		spin_lock_irqsave(&hsotg->lock, flags);
-		hprt0 = dwc2_read_hprt0(hsotg);
-		hprt0 &= ~(HPRT0_RES | HPRT0_SUSP);
-		dwc2_writel(hsotg, hprt0, HPRT0);
-		hsotg->bus_suspended = false;
+		break;
 	}
 
 	spin_unlock_irqrestore(&hsotg->lock, flags);