phy: exynos-usb2: add vbus regulator support

Exynos USB2 PHY has separate power supply, which is usually provided by
VBUS regulator. This patch adds support for it. VBUS regulator is
optional, to keep compatibility with boards, which have VBUS provided
from some always-on power source.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Tested-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>

Documentation/devicetree/bindings/phy/samsung-phy.txt

@@ -44,6 +44,9 @@ Required properties:
 	- the "ref" clock is used to get the rate of the clock provided to the
 	  PHY module
 
+Optional properties:
+- vbus-supply: power-supply phandle for vbus power source
+
 The first phandle argument in the PHY specifier identifies the PHY, its
 meaning is compatible dependent. For the currently supported SoCs (Exynos 4210
 and Exynos 4212) it is as follows:

drivers/phy/phy-samsung-usb2.c

@@ -27,6 +27,13 @@ static int samsung_usb2_phy_power_on(struct phy *phy)
 
 	dev_dbg(drv->dev, "Request to power_on \"%s\" usb phy\n",
 		inst->cfg->label);
+
+	if (drv->vbus) {
+		ret = regulator_enable(drv->vbus);
+		if (ret)
+			goto err_regulator;
+	}
+
 	ret = clk_prepare_enable(drv->clk);
 	if (ret)
 		goto err_main_clk;
@@ -48,6 +55,9 @@ err_power_on:
 err_instance_clk:
 	clk_disable_unprepare(drv->clk);
 err_main_clk:
+	if (drv->vbus)
+		regulator_disable(drv->vbus);
+err_regulator:
 	return ret;
 }
 
@@ -55,7 +65,7 @@ static int samsung_usb2_phy_power_off(struct phy *phy)
 {
 	struct samsung_usb2_phy_instance *inst = phy_get_drvdata(phy);
 	struct samsung_usb2_phy_driver *drv = inst->drv;
-	int ret;
+	int ret = 0;
 
 	dev_dbg(drv->dev, "Request to power_off \"%s\" usb phy\n",
 		inst->cfg->label);
@@ -68,7 +78,10 @@ static int samsung_usb2_phy_power_off(struct phy *phy)
 	}
 	clk_disable_unprepare(drv->ref_clk);
 	clk_disable_unprepare(drv->clk);
-	return 0;
+	if (drv->vbus)
+		ret = regulator_disable(drv->vbus);
+
+	return ret;
 }
 
 static const struct phy_ops samsung_usb2_phy_ops = {
@@ -203,6 +216,14 @@ static int samsung_usb2_phy_probe(struct platform_device *pdev)
 			return ret;
 	}
 
+	drv->vbus = devm_regulator_get(dev, "vbus");
+	if (IS_ERR(drv->vbus)) {
+		ret = PTR_ERR(drv->vbus);
+		if (ret == -EPROBE_DEFER)
+			return ret;
+		drv->vbus = NULL;
+	}
+
 	for (i = 0; i < drv->cfg->num_phys; i++) {
 		char *label = drv->cfg->phys[i].label;
 		struct samsung_usb2_phy_instance *p = &drv->instances[i];

drivers/phy/phy-samsung-usb2.h

@@ -17,6 +17,7 @@
 #include <linux/device.h>
 #include <linux/regmap.h>
 #include <linux/spinlock.h>
+#include <linux/regulator/consumer.h>
 
 #define KHZ 1000
 #define MHZ (KHZ * KHZ)
@@ -37,6 +38,7 @@ struct samsung_usb2_phy_driver {
 	const struct samsung_usb2_phy_config *cfg;
 	struct clk *clk;
 	struct clk *ref_clk;
+	struct regulator *vbus;
 	unsigned long ref_rate;
 	u32 ref_reg_val;
 	struct device *dev;