usb: dwc2: Add host clock gating support functions

Added host clock gating support functions according
programming guide.

Added function names:
dwc2_host_enter_clock_gating()
dwc2_host_exit_clock_gating()
Acked-by: Minas Harutyunyan <Minas.Harutyunyan@synopsys.com>
Signed-off-by: Artur Petrosyan <Arthur.Petrosyan@synopsys.com>
Link: https://lore.kernel.org/r/20210413073615.B3E84A022E@mailhost.synopsys.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/dwc2/core.h

@@ -1486,6 +1486,8 @@ int dwc2_host_exit_hibernation(struct dwc2_hsotg *hsotg,
 int dwc2_host_enter_partial_power_down(struct dwc2_hsotg *hsotg);
 int dwc2_host_exit_partial_power_down(struct dwc2_hsotg *hsotg,
 				      int rem_wakeup, bool restore);
+void dwc2_host_enter_clock_gating(struct dwc2_hsotg *hsotg);
+void dwc2_host_exit_clock_gating(struct dwc2_hsotg *hsotg, int rem_wakeup);
 bool dwc2_host_can_poweroff_phy(struct dwc2_hsotg *dwc2);
 static inline void dwc2_host_schedule_phy_reset(struct dwc2_hsotg *hsotg)
 { schedule_work(&hsotg->phy_reset_work); }
@@ -1521,6 +1523,9 @@ static inline int dwc2_host_enter_partial_power_down(struct dwc2_hsotg *hsotg)
 static inline int dwc2_host_exit_partial_power_down(struct dwc2_hsotg *hsotg,
 						    int rem_wakeup, bool restore)
 { return 0; }
+static inline void dwc2_host_enter_clock_gating(struct dwc2_hsotg *hsotg) {}
+static inline void dwc2_host_exit_clock_gating(struct dwc2_hsotg *hsotg,
+					       int rem_wakeup) {}
 static inline bool dwc2_host_can_poweroff_phy(struct dwc2_hsotg *dwc2)
 { return false; }
 static inline void dwc2_host_schedule_phy_reset(struct dwc2_hsotg *hsotg) {}

drivers/usb/dwc2/hcd.c

@@ -5821,3 +5821,89 @@ int dwc2_host_exit_partial_power_down(struct dwc2_hsotg *hsotg,
 	dev_dbg(hsotg->dev, "Exiting host partial power down completed.\n");
 	return ret;
 }
+
+/**
+ * dwc2_host_enter_clock_gating() - Put controller in clock gating.
+ *
+ * @hsotg: Programming view of the DWC_otg controller
+ *
+ * This function is for entering Host mode clock gating.
+ */
+void dwc2_host_enter_clock_gating(struct dwc2_hsotg *hsotg)
+{
+	u32 hprt0;
+	u32 pcgctl;
+
+	dev_dbg(hsotg->dev, "Entering host clock gating.\n");
+
+	/* Put this port in suspend mode. */
+	hprt0 = dwc2_read_hprt0(hsotg);
+	hprt0 |= HPRT0_SUSP;
+	dwc2_writel(hsotg, hprt0, HPRT0);
+
+	/* Set the Phy Clock bit as suspend is received. */
+	pcgctl = dwc2_readl(hsotg, PCGCTL);
+	pcgctl |= PCGCTL_STOPPCLK;
+	dwc2_writel(hsotg, pcgctl, PCGCTL);
+	udelay(5);
+
+	/* Set the Gate hclk as suspend is received. */
+	pcgctl = dwc2_readl(hsotg, PCGCTL);
+	pcgctl |= PCGCTL_GATEHCLK;
+	dwc2_writel(hsotg, pcgctl, PCGCTL);
+	udelay(5);
+
+	hsotg->bus_suspended = true;
+	hsotg->lx_state = DWC2_L2;
+}
+
+/**
+ * dwc2_host_exit_clock_gating() - Exit controller from clock gating.
+ *
+ * @hsotg: Programming view of the DWC_otg controller
+ * @rem_wakeup: indicates whether resume is initiated by remote wakeup
+ *
+ * This function is for exiting Host mode clock gating.
+ */
+void dwc2_host_exit_clock_gating(struct dwc2_hsotg *hsotg, int rem_wakeup)
+{
+	u32 hprt0;
+	u32 pcgctl;
+
+	dev_dbg(hsotg->dev, "Exiting host clock gating.\n");
+
+	/* Clear the Gate hclk. */
+	pcgctl = dwc2_readl(hsotg, PCGCTL);
+	pcgctl &= ~PCGCTL_GATEHCLK;
+	dwc2_writel(hsotg, pcgctl, PCGCTL);
+	udelay(5);
+
+	/* Phy Clock bit. */
+	pcgctl = dwc2_readl(hsotg, PCGCTL);
+	pcgctl &= ~PCGCTL_STOPPCLK;
+	dwc2_writel(hsotg, pcgctl, PCGCTL);
+	udelay(5);
+
+	/* Drive resume signaling and exit suspend mode on the port. */
+	hprt0 = dwc2_read_hprt0(hsotg);
+	hprt0 |= HPRT0_RES;
+	hprt0 &= ~HPRT0_SUSP;
+	dwc2_writel(hsotg, hprt0, HPRT0);
+	udelay(5);
+
+	if (!rem_wakeup) {
+		/* In case of port resume need to wait for 40 ms */
+		msleep(USB_RESUME_TIMEOUT);
+
+		/* Stop driveing resume signaling on the port. */
+		hprt0 = dwc2_read_hprt0(hsotg);
+		hprt0 &= ~HPRT0_RES;
+		dwc2_writel(hsotg, hprt0, HPRT0);
+
+		hsotg->bus_suspended = false;
+		hsotg->lx_state = DWC2_L0;
+	} else {
+		mod_timer(&hsotg->wkp_timer,
+			  jiffies + msecs_to_jiffies(71));
+	}
+}