[PATCH v2 2/9] usb: phy: nop: Don't use regulator framework for RESET line

[Roger Quadros]

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 <rogerq at ti.com>
---
 .../devicetree/bindings/usb/usb-nop-xceiv.txt      |    7 +-
 drivers/usb/phy/phy-nop.c                          |   71 ++++++++++++++-----
 2 files changed, 55 insertions(+), 23 deletions(-)

diff --git a/Documentation/devicetree/bindings/usb/usb-nop-xceiv.txt b/Documentation/devicetree/bindings/usb/usb-nop-xceiv.txt
index d7e2726..1bd37fa 100644
--- a/Documentation/devicetree/bindings/usb/usb-nop-xceiv.txt
+++ b/Documentation/devicetree/bindings/usb/usb-nop-xceiv.txt
@@ -15,7 +15,7 @@ Optional properties:
 
 - 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:
 
@@ -25,10 +25,9 @@ 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.
diff --git a/drivers/usb/phy/phy-nop.c b/drivers/usb/phy/phy-nop.c
index 55445e5d..1f88c32 100644
--- a/drivers/usb/phy/phy-nop.c
+++ b/drivers/usb/phy/phy-nop.c
@@ -35,6 +35,9 @@
 #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>
 
 struct nop_usb_xceiv {
 	struct usb_phy phy;
@@ -42,6 +45,8 @@ struct nop_usb_xceiv {
 	struct clk *clk;
 	struct regulator *vcc;
 	struct regulator *reset;
+	int gpio_reset;
+	bool reset_active_low;
 };
 
 static struct platform_device *pd;
@@ -70,6 +75,23 @@ static int nop_set_suspend(struct usb_phy *x, int suspend)
 	return 0;
 }
 
+static void nop_reset_set(struct nop_usb_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);
+}
+
 static int nop_init(struct usb_phy *phy)
 {
 	struct nop_usb_xceiv *nop = dev_get_drvdata(phy->dev);
@@ -82,11 +104,8 @@ static int nop_init(struct usb_phy *phy)
 	if (!IS_ERR(nop->clk))
 		clk_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;
 }
@@ -95,11 +114,8 @@ static void nop_shutdown(struct usb_phy *phy)
 {
 	struct nop_usb_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(nop->clk);
@@ -148,7 +164,6 @@ static int nop_usb_xceiv_probe(struct platform_device *pdev)
 	int err;
 	u32 clk_rate = 0;
 	bool needs_vcc = false;
-	bool needs_reset = false;
 
 	nop = devm_kzalloc(&pdev->dev, sizeof(*nop), GFP_KERNEL);
 	if (!nop)
@@ -159,20 +174,28 @@ static int nop_usb_xceiv_probe(struct platform_device *pdev)
 	if (!nop->phy.otg)
 		return -ENOMEM;
 
+	nop->reset_active_low = true;	/* default behaviour */
+
 	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");
-		needs_reset = of_property_read_bool(node, "reset-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;
-		needs_reset = pdata->needs_reset;
+		nop->gpio_reset = pdata->gpio_reset;
 	}
 
 	nop->clk = devm_clk_get(&pdev->dev, "main_clk");
@@ -205,12 +228,22 @@ static int nop_usb_xceiv_probe(struct platform_device *pdev)
 			return -EPROBE_DEFER;
 	}
 
-	nop->reset = devm_regulator_get(&pdev->dev, "reset");
-	if (IS_ERR(nop->reset)) {
-		dev_dbg(&pdev->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_HIGH;
+		else
+			gpio_flags = GPIOF_OUT_INIT_LOW;
+
+		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		= &pdev->dev;
-- 
1.7.4.1