phy: tegra: xusb: Add usb-role-switch support

If usb-role-switch property is present in USB 2 port, register
usb-role-switch to receive usb role changes.

Signed-off-by: Nagarjuna Kristam <nkristam@nvidia.com>
Acked-by: Kishon Vijay Abraham I <kishon@ti.com>
[treding@nvidia.com: rebase onto Greg's usb-next branch]
Signed-off-by: Thierry Reding <treding@nvidia.com>

drivers/phy/tegra/Kconfig

@@ -2,6 +2,7 @@
 config PHY_TEGRA_XUSB
 	tristate "NVIDIA Tegra XUSB pad controller driver"
 	depends on ARCH_TEGRA
+	select USB_CONN_GPIO
 	help
 	  Choose this option if you have an NVIDIA Tegra SoC.
 

drivers/phy/tegra/xusb.c

@@ -541,6 +541,11 @@ unregister:
 
 static void tegra_xusb_port_unregister(struct tegra_xusb_port *port)
 {
+	if (!IS_ERR_OR_NULL(port->usb_role_sw)) {
+		of_platform_depopulate(&port->dev);
+		usb_role_switch_unregister(port->usb_role_sw);
+	}
+
 	device_unregister(&port->dev);
 }
 
@@ -551,11 +556,64 @@ static const char *const modes[] = {
 	[USB_DR_MODE_OTG] = "otg",
 };
 
+static const char * const usb_roles[] = {
+	[USB_ROLE_NONE]		= "none",
+	[USB_ROLE_HOST]		= "host",
+	[USB_ROLE_DEVICE]	= "device",
+};
+
+static int tegra_xusb_role_sw_set(struct usb_role_switch *sw,
+				  enum usb_role role)
+{
+	struct tegra_xusb_port *port = usb_role_switch_get_drvdata(sw);
+
+	dev_dbg(&port->dev, "%s(): role %s\n", __func__, usb_roles[role]);
+
+	return 0;
+}
+
+static int tegra_xusb_setup_usb_role_switch(struct tegra_xusb_port *port)
+{
+	struct usb_role_switch_desc role_sx_desc = {
+		.fwnode = dev_fwnode(&port->dev),
+		.set = tegra_xusb_role_sw_set,
+	};
+	int err = 0;
+
+	/*
+	 * USB role switch driver needs parent driver owner info. This is a
+	 * suboptimal solution. TODO: Need to revisit this in a follow-up patch
+	 * where an optimal solution is possible with changes to USB role
+	 * switch driver.
+	 */
+	port->dev.driver = devm_kzalloc(&port->dev,
+					sizeof(struct device_driver),
+					GFP_KERNEL);
+	port->dev.driver->owner	 = THIS_MODULE;
+
+	port->usb_role_sw = usb_role_switch_register(&port->dev,
+						     &role_sx_desc);
+	if (IS_ERR(port->usb_role_sw)) {
+		err = PTR_ERR(port->usb_role_sw);
+		dev_err(&port->dev, "failed to register USB role switch: %d",
+			err);
+		return err;
+	}
+
+	usb_role_switch_set_drvdata(port->usb_role_sw, port);
+
+	/* populate connector entry */
+	of_platform_populate(port->dev.of_node, NULL, NULL, &port->dev);
+
+	return err;
+}
+
 static int tegra_xusb_usb2_port_parse_dt(struct tegra_xusb_usb2_port *usb2)
 {
 	struct tegra_xusb_port *port = &usb2->base;
 	struct device_node *np = port->dev.of_node;
 	const char *mode;
+	int err;
 
 	usb2->internal = of_property_read_bool(np, "nvidia,internal");
 
@@ -572,6 +630,20 @@ static int tegra_xusb_usb2_port_parse_dt(struct tegra_xusb_usb2_port *usb2)
 		usb2->mode = USB_DR_MODE_HOST;
 	}
 
+	/* usb-role-switch property is mandatory for OTG/Peripheral modes */
+	if (usb2->mode == USB_DR_MODE_PERIPHERAL ||
+	    usb2->mode == USB_DR_MODE_OTG) {
+		if (of_property_read_bool(np, "usb-role-switch")) {
+			err = tegra_xusb_setup_usb_role_switch(port);
+			if (err < 0)
+				return err;
+		} else {
+			dev_err(&port->dev, "usb-role-switch not found for %s mode",
+				modes[usb2->mode]);
+			return -EINVAL;
+		}
+	}
+
 	usb2->supply = devm_regulator_get(&port->dev, "vbus");
 	return PTR_ERR_OR_ZERO(usb2->supply);
 }

drivers/phy/tegra/xusb.h

@@ -12,6 +12,7 @@
 #include <linux/workqueue.h>
 
 #include <linux/usb/otg.h>
+#include <linux/usb/role.h>
 
 /* legacy entry points for backwards-compatibility */
 int tegra_xusb_padctl_legacy_probe(struct platform_device *pdev);
@@ -266,6 +267,8 @@ struct tegra_xusb_port {
 	struct list_head list;
 	struct device dev;
 
+	struct usb_role_switch *usb_role_sw;
+
 	const struct tegra_xusb_port_ops *ops;
 };