usb: dwc3: keystone: Turn on USB3 PHY before controller

The Local Power Sleep Controller (LPSC) dependency on AM65
requires SERDES0 to be powered on before USB.

We need to power up SERDES0 power domain and hold it on
throughout the reset, init, power on sequence.
Signed-off-by: Roger Quadros <rogerq@ti.com>
Signed-off-by: Felipe Balbi <balbi@kernel.org>

drivers/usb/dwc3/dwc3-keystone.c

@@ -14,6 +14,7 @@
 #include <linux/dma-mapping.h>
 #include <linux/io.h>
 #include <linux/of_platform.h>
+#include <linux/phy/phy.h>
 #include <linux/pm_runtime.h>
 
 /* USBSS register offsets */
@@ -34,6 +35,7 @@
 struct dwc3_keystone {
 	struct device			*dev;
 	void __iomem			*usbss;
+	struct phy			*usb3_phy;
 };
 
 static inline u32 kdwc3_readl(void __iomem *base, u32 offset)
@@ -95,8 +97,38 @@ static int kdwc3_probe(struct platform_device *pdev)
 	if (IS_ERR(kdwc->usbss))
 		return PTR_ERR(kdwc->usbss);
 
-	pm_runtime_enable(kdwc->dev);
+	/* PSC dependency on AM65 needs SERDES0 to be powered before USB0 */
+	kdwc->usb3_phy = devm_phy_optional_get(dev, "usb3-phy");
+	if (IS_ERR(kdwc->usb3_phy)) {
+		error = PTR_ERR(kdwc->usb3_phy);
+		if (error != -EPROBE_DEFER)
+			dev_err(dev, "couldn't get usb3 phy: %d\n", error);
+
+		return error;
+	}
+
+	phy_pm_runtime_get_sync(kdwc->usb3_phy);
 
+	error = phy_reset(kdwc->usb3_phy);
+	if (error < 0) {
+		dev_err(dev, "usb3 phy reset failed: %d\n", error);
+		return error;
+	}
+
+	error = phy_init(kdwc->usb3_phy);
+	if (error < 0) {
+		dev_err(dev, "usb3 phy init failed: %d\n", error);
+		return error;
+	}
+
+	error = phy_power_on(kdwc->usb3_phy);
+	if (error < 0) {
+		dev_err(dev, "usb3 phy power on failed: %d\n", error);
+		phy_exit(kdwc->usb3_phy);
+		return error;
+	}
+
+	pm_runtime_enable(kdwc->dev);
 	error = pm_runtime_get_sync(kdwc->dev);
 	if (error < 0) {
 		dev_err(kdwc->dev, "pm_runtime_get_sync failed, error %d\n",
@@ -138,6 +170,9 @@ static int kdwc3_probe(struct platform_device *pdev)
 err_irq:
 	pm_runtime_put_sync(kdwc->dev);
 	pm_runtime_disable(kdwc->dev);
+	phy_power_off(kdwc->usb3_phy);
+	phy_exit(kdwc->usb3_phy);
+	phy_pm_runtime_put_sync(kdwc->usb3_phy);
 
 	return error;
 }
@@ -163,6 +198,10 @@ static int kdwc3_remove(struct platform_device *pdev)
 	pm_runtime_put_sync(kdwc->dev);
 	pm_runtime_disable(kdwc->dev);
 
+	phy_power_off(kdwc->usb3_phy);
+	phy_exit(kdwc->usb3_phy);
+	phy_pm_runtime_put_sync(kdwc->usb3_phy);
+
 	platform_set_drvdata(pdev, NULL);
 
 	return 0;