usb: phy: generic: Don't use regulator framework for RESET line

Modelling the RESET line as a regulator supply wasn't a good idea
as it kind of abuses the regulator framework and also makes adaptation
code more complex.

Instead, manage the RESET gpio line directly in the driver. Update
the device tree binding information.

This also makes us easy to migrate to a dedicated GPIO RESET controller
whenever it becomes available.

Signed-off-by: Roger Quadros <[e-mail]>
Signed-off-by: Felipe Balbi <[e-mail]>

Documentation/devicetree/bindings/usb/usb-nop-xceiv.txt

···
 
 - vcc-supply: phandle to the regulator that provides RESET to the PHY.
 
-- reset-supply: phandle to the regulator that provides power to the PHY.
+- reset-gpios: Should specify the GPIO for reset.
 
 Example:
 
···
 		clocks = <&osc 0>;
 		clock-names = "main_clk";
 		vcc-supply = <&hsusb1_vcc_regulator>;
-		reset-supply = <&hsusb1_reset_regulator>;
+		reset-gpios = <&gpio1 7 GPIO_ACTIVE_LOW>;
 	};
 
 hsusb1_phy is a NOP USB PHY device that gets its clock from an oscillator
 and expects that clock to be configured to 19.2MHz by the NOP PHY driver.
-hsusb1_vcc_regulator provides power to the PHY and hsusb1_reset_regulator
-controls RESET.
+hsusb1_vcc_regulator provides power to the PHY and GPIO 7 controls RESET.

drivers/usb/phy/phy-am335x.c

···
 	}
 
 	ret = usb_phy_gen_create_phy(dev, &am_phy->usb_phy_gen,
-			USB_PHY_TYPE_USB2, 0, false, false);
+			USB_PHY_TYPE_USB2, 0, false);
 	if (ret)
 		return ret;
 

drivers/usb/phy/phy-generic.c

···
 #include <linux/clk.h>
 #include <linux/regulator/consumer.h>
 #include <linux/of.h>
+#include <linux/of_gpio.h>
+#include <linux/gpio.h>
+#include <linux/delay.h>
 
 #include "phy-generic.h"
 
···
 	return 0;
 }
 
+static void nop_reset_set(struct usb_phy_gen_xceiv *nop, int asserted)
+{
+	int value;
+
+	if (!gpio_is_valid(nop->gpio_reset))
+		return;
+
+	value = asserted;
+	if (nop->reset_active_low)
+		value = !value;
+
+	gpio_set_value_cansleep(nop->gpio_reset, value);
+
+	if (!asserted)
+		usleep_range(10000, 20000);
+}
+
 int usb_gen_phy_init(struct usb_phy *phy)
 {
 	struct usb_phy_gen_xceiv *nop = dev_get_drvdata(phy->dev);
···
 	if (!IS_ERR(nop->clk))
 		clk_prepare_enable(nop->clk);
 
-	if (!IS_ERR(nop->reset)) {
-		/* De-assert RESET */
-		if (regulator_enable(nop->reset))
-			dev_err(phy->dev, "Failed to de-assert reset\n");
-	}
+	/* De-assert RESET */
+	nop_reset_set(nop, 0);
 
 	return 0;
 }
···
 {
 	struct usb_phy_gen_xceiv *nop = dev_get_drvdata(phy->dev);
 
-	if (!IS_ERR(nop->reset)) {
-		/* Assert RESET */
-		if (regulator_disable(nop->reset))
-			dev_err(phy->dev, "Failed to assert reset\n");
-	}
+	/* Assert RESET */
+	nop_reset_set(nop, 1);
 
 	if (!IS_ERR(nop->clk))
 		clk_disable_unprepare(nop->clk);
···
 }
 
 int usb_phy_gen_create_phy(struct device *dev, struct usb_phy_gen_xceiv *nop,
-		enum usb_phy_type type, u32 clk_rate, bool needs_vcc,
-		bool needs_reset)
+		enum usb_phy_type type, u32 clk_rate, bool needs_vcc)
 {
 	int err;
 
···
 			return -EPROBE_DEFER;
 	}
 
-	nop->reset = devm_regulator_get(dev, "reset");
-	if (IS_ERR(nop->reset)) {
-		dev_dbg(dev, "Error getting reset regulator: %ld\n",
-					PTR_ERR(nop->reset));
-		if (needs_reset)
-			return -EPROBE_DEFER;
+	if (gpio_is_valid(nop->gpio_reset)) {
+		unsigned long gpio_flags;
+
+		/* Assert RESET */
+		if (nop->reset_active_low)
+			gpio_flags = GPIOF_OUT_INIT_LOW;
+		else
+			gpio_flags = GPIOF_OUT_INIT_HIGH;
+
+		err = devm_gpio_request_one(dev, nop->gpio_reset,
+						gpio_flags, dev_name(dev));
+		if (err) {
+			dev_err(dev, "Error requesting RESET GPIO %d\n",
+					nop->gpio_reset);
+			return err;
+		}
 	}
 
 	nop->dev		= dev;
···
 	int err;
 	u32 clk_rate = 0;
 	bool needs_vcc = false;
-	bool needs_reset = false;
-
-	if (dev->of_node) {
-		struct device_node *node = dev->of_node;
-
-		if (of_property_read_u32(node, "clock-frequency", &clk_rate))
-			clk_rate = 0;
-
-		needs_vcc = of_property_read_bool(node, "vcc-supply");
-		needs_reset = of_property_read_bool(node, "reset-supply");
-
-	} else if (pdata) {
-		type = pdata->type;
-		clk_rate = pdata->clk_rate;
-		needs_vcc = pdata->needs_vcc;
-		needs_reset = pdata->needs_reset;
-	}
 
 	nop = devm_kzalloc(dev, sizeof(*nop), GFP_KERNEL);
 	if (!nop)
 		return -ENOMEM;
 
+	nop->reset_active_low = true;	/* default behaviour */
 
-	err = usb_phy_gen_create_phy(dev, nop, type, clk_rate, needs_vcc,
-			needs_reset);
+	if (dev->of_node) {
+		struct device_node *node = dev->of_node;
+		enum of_gpio_flags flags;
+
+		if (of_property_read_u32(node, "clock-frequency", &clk_rate))
+			clk_rate = 0;
+
+		needs_vcc = of_property_read_bool(node, "vcc-supply");
+		nop->gpio_reset = of_get_named_gpio_flags(node, "reset-gpios",
+								0, &flags);
+		if (nop->gpio_reset == -EPROBE_DEFER)
+			return -EPROBE_DEFER;
+
+		nop->reset_active_low = flags & OF_GPIO_ACTIVE_LOW;
+
+	} else if (pdata) {
+		type = pdata->type;
+		clk_rate = pdata->clk_rate;
+		needs_vcc = pdata->needs_vcc;
+		nop->gpio_reset = pdata->gpio_reset;
+	}
+
+	err = usb_phy_gen_create_phy(dev, nop, type, clk_rate, needs_vcc);
 	if (err)
 		return err;
 

drivers/usb/phy/phy-generic.h

···
 	struct device *dev;
 	struct clk *clk;
 	struct regulator *vcc;
-	struct regulator *reset;
+	int gpio_reset;
+	bool reset_active_low;
 };
 
 int usb_gen_phy_init(struct usb_phy *phy);
 void usb_gen_phy_shutdown(struct usb_phy *phy);
 
 int usb_phy_gen_create_phy(struct device *dev, struct usb_phy_gen_xceiv *nop,
-		enum usb_phy_type type, u32 clk_rate, bool needs_vcc,
-		bool needs_reset);
+		enum usb_phy_type type, u32 clk_rate, bool needs_vcc);
 
 #endif