usb: dwc2: Add enter partial power down when port is suspended

Adds flow of entering Partial Power Down in
"dwc2_port_suspend()" function when core receives suspend.

NOTE: Switch case statement is used for hibernation partial
power down and clock gating mode determination. In this patch
only Partial Power Down is implemented the Hibernation and
clock gating implementations are planned to be added.
Acked-by: Minas Harutyunyan <Minas.Harutyunyan@synopsys.com>
Signed-off-by: Artur Petrosyan <Arthur.Petrosyan@synopsys.com>
Link: https://lore.kernel.org/r/20210408094510.6C4E9A022E@mailhost.synopsys.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/dwc2/core.h

@@ -1470,7 +1470,7 @@ void dwc2_hcd_connect(struct dwc2_hsotg *hsotg);
 void dwc2_hcd_disconnect(struct dwc2_hsotg *hsotg, bool force);
 void dwc2_hcd_start(struct dwc2_hsotg *hsotg);
 int dwc2_core_init(struct dwc2_hsotg *hsotg, bool initial_setup);
-void dwc2_port_suspend(struct dwc2_hsotg *hsotg, u16 windex);
+int dwc2_port_suspend(struct dwc2_hsotg *hsotg, u16 windex);
 void dwc2_port_resume(struct dwc2_hsotg *hsotg);
 int dwc2_backup_host_registers(struct dwc2_hsotg *hsotg);
 int dwc2_restore_host_registers(struct dwc2_hsotg *hsotg);
@@ -1495,7 +1495,8 @@ static inline void dwc2_hcd_start(struct dwc2_hsotg *hsotg) {}
 static inline void dwc2_hcd_remove(struct dwc2_hsotg *hsotg) {}
 static inline int dwc2_core_init(struct dwc2_hsotg *hsotg, bool initial_setup)
 { return 0; }
-static inline void dwc2_port_suspend(struct dwc2_hsotg *hsotg, u16 windex) {}
+static inline int dwc2_port_suspend(struct dwc2_hsotg *hsotg, u16 windex)
+{ return 0; }
 static inline void dwc2_port_resume(struct dwc2_hsotg *hsotg) {}
 static inline int dwc2_hcd_init(struct dwc2_hsotg *hsotg)
 { return 0; }

drivers/usb/dwc2/hcd.c

@@ -3281,15 +3281,18 @@ static int dwc2_host_is_b_hnp_enabled(struct dwc2_hsotg *hsotg)
  * @hsotg: Programming view of the DWC_otg controller
  * @windex: The control request wIndex field
  *
+ * Return: non-zero if failed to enter suspend mode for host.
+ *
  * This function is for entering Host mode suspend.
  * Must NOT be called with interrupt disabled or spinlock held.
  */
-void dwc2_port_suspend(struct dwc2_hsotg *hsotg, u16 windex)
+int dwc2_port_suspend(struct dwc2_hsotg *hsotg, u16 windex)
 {
 	unsigned long flags;
 	u32 hprt0;
 	u32 pcgctl;
 	u32 gotgctl;
+	int ret = 0;
 
 	dev_dbg(hsotg->dev, "%s()\n", __func__);
 
@@ -3302,22 +3305,31 @@ void dwc2_port_suspend(struct dwc2_hsotg *hsotg, u16 windex)
 		hsotg->op_state = OTG_STATE_A_SUSPEND;
 	}
 
-	hprt0 = dwc2_read_hprt0(hsotg);
-	hprt0 |= HPRT0_SUSP;
-	dwc2_writel(hsotg, hprt0, HPRT0);
-
-	hsotg->bus_suspended = true;
-
-	/*
-	 * If power_down is supported, Phy clock will be suspended
-	 * after registers are backuped.
-	 */
-	if (!hsotg->params.power_down) {
-		/* Suspend the Phy Clock */
-		pcgctl = dwc2_readl(hsotg, PCGCTL);
-		pcgctl |= PCGCTL_STOPPCLK;
-		dwc2_writel(hsotg, pcgctl, PCGCTL);
-		udelay(10);
+	switch (hsotg->params.power_down) {
+	case DWC2_POWER_DOWN_PARAM_PARTIAL:
+		ret = dwc2_enter_partial_power_down(hsotg);
+		if (ret)
+			dev_err(hsotg->dev,
+				"enter partial_power_down failed.\n");
+		break;
+	case DWC2_POWER_DOWN_PARAM_HIBERNATION:
+	case DWC2_POWER_DOWN_PARAM_NONE:
+	default:
+		hprt0 = dwc2_read_hprt0(hsotg);
+		hprt0 |= HPRT0_SUSP;
+		dwc2_writel(hsotg, hprt0, HPRT0);
+		hsotg->bus_suspended = true;
+		/*
+		 * If power_down is supported, Phy clock will be suspended
+		 * after registers are backuped.
+		 */
+		if (!hsotg->params.power_down) {
+			/* Suspend the Phy Clock */
+			pcgctl = dwc2_readl(hsotg, PCGCTL);
+			pcgctl |= PCGCTL_STOPPCLK;
+			dwc2_writel(hsotg, pcgctl, PCGCTL);
+			udelay(10);
+		}
 	}
 
 	/* For HNP the bus must be suspended for at least 200ms */
@@ -3332,6 +3344,8 @@ void dwc2_port_suspend(struct dwc2_hsotg *hsotg, u16 windex)
 	} else {
 		spin_unlock_irqrestore(&hsotg->lock, flags);
 	}
+
+	return ret;
 }
 
 /**