2 files changed, 306 insertions, 0 deletions

diff --git a/drivers/usb/common/Makefile b/drivers/usb/common/Makefile
index 0a7c45e85481..fb4d5ef4165c 100644
--- a/drivers/usb/common/Makefile
+++ b/drivers/usb/common/Makefile
@@ -9,3 +9,4 @@ usb-common-$(CONFIG_USB_LED_TRIG) += led.o
 
 obj-$(CONFIG_USB_OTG_FSM) += usb-otg-fsm.o
 obj-$(CONFIG_USB_ULPI_BUS)	+= ulpi.o
+obj-$(CONFIG_USB_ROLE_SWITCH)	+= roles.o
diff --git a/drivers/usb/common/roles.c b/drivers/usb/common/roles.c
new file mode 100644
index 000000000000..15cc76e22123
--- /dev/null
+++ b/drivers/usb/common/roles.c
@@ -0,0 +1,305 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * USB Role Switch Support
+ *
+ * Copyright (C) 2018 Intel Corporation
+ * Author: Heikki Krogerus <heikki.krogerus@linux.intel.com>
+ *         Hans de Goede <hdegoede@redhat.com>
+ */
+
+#include <linux/usb/role.h>
+#include <linux/device.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/slab.h>
+
+static struct class *role_class;
+
+struct usb_role_switch {
+	struct device dev;
+	struct mutex lock; /* device lock*/
+	enum usb_role role;
+
+	/* From descriptor */
+	struct device *usb2_port;
+	struct device *usb3_port;
+	struct device *udc;
+	usb_role_switch_set_t set;
+	usb_role_switch_get_t get;
+	bool allow_userspace_control;
+};
+
+#define to_role_switch(d)	container_of(d, struct usb_role_switch, dev)
+
+/**
+ * usb_role_switch_set_role - Set USB role for a switch
+ * @sw: USB role switch
+ * @role: USB role to be switched to
+ *
+ * Set USB role @role for @sw.
+ */
+int usb_role_switch_set_role(struct usb_role_switch *sw, enum usb_role role)
+{
+	int ret;
+
+	if (IS_ERR_OR_NULL(sw))
+		return 0;
+
+	mutex_lock(&sw->lock);
+
+	ret = sw->set(sw->dev.parent, role);
+	if (!ret)
+		sw->role = role;
+
+	mutex_unlock(&sw->lock);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(usb_role_switch_set_role);
+
+/**
+ * usb_role_switch_get_role - Get the USB role for a switch
+ * @sw: USB role switch
+ *
+ * Depending on the role-switch-driver this function returns either a cached
+ * value of the last set role, or reads back the actual value from the hardware.
+ */
+enum usb_role usb_role_switch_get_role(struct usb_role_switch *sw)
+{
+	enum usb_role role;
+
+	if (IS_ERR_OR_NULL(sw))
+		return USB_ROLE_NONE;
+
+	mutex_lock(&sw->lock);
+
+	if (sw->get)
+		role = sw->get(sw->dev.parent);
+	else
+		role = sw->role;
+
+	mutex_unlock(&sw->lock);
+
+	return role;
+}
+EXPORT_SYMBOL_GPL(usb_role_switch_get_role);
+
+static int __switch_match(struct device *dev, const void *name)
+{
+	return !strcmp((const char *)name, dev_name(dev));
+}
+
+static void *usb_role_switch_match(struct device_connection *con, int ep,
+				   void *data)
+{
+	struct device *dev;
+
+	dev = class_find_device(role_class, NULL, con->endpoint[ep],
+				__switch_match);
+
+	return dev ? to_role_switch(dev) : ERR_PTR(-EPROBE_DEFER);
+}
+
+/**
+ * usb_role_switch_get - Find USB role switch linked with the caller
+ * @dev: The caller device
+ *
+ * Finds and returns role switch linked with @dev. The reference count for the
+ * found switch is incremented.
+ */
+struct usb_role_switch *usb_role_switch_get(struct device *dev)
+{
+	return device_connection_find_match(dev, "usb-role-switch", NULL,
+					    usb_role_switch_match);
+}
+EXPORT_SYMBOL_GPL(usb_role_switch_get);
+
+/**
+ * usb_role_switch_put - Release handle to a switch
+ * @sw: USB Role Switch
+ *
+ * Decrement reference count for @sw.
+ */
+void usb_role_switch_put(struct usb_role_switch *sw)
+{
+	if (!IS_ERR_OR_NULL(sw))
+		put_device(&sw->dev);
+}
+EXPORT_SYMBOL_GPL(usb_role_switch_put);
+
+static umode_t
+usb_role_switch_is_visible(struct kobject *kobj, struct attribute *attr, int n)
+{
+	struct device *dev = container_of(kobj, typeof(*dev), kobj);
+	struct usb_role_switch *sw = to_role_switch(dev);
+
+	if (sw->allow_userspace_control)
+		return attr->mode;
+
+	return 0;
+}
+
+static const char * const usb_roles[] = {
+	[USB_ROLE_NONE]		= "none",
+	[USB_ROLE_HOST]		= "host",
+	[USB_ROLE_DEVICE]	= "device",
+};
+
+static ssize_t
+role_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	struct usb_role_switch *sw = to_role_switch(dev);
+	enum usb_role role = usb_role_switch_get_role(sw);
+
+	return sprintf(buf, "%s\n", usb_roles[role]);
+}
+
+static ssize_t role_store(struct device *dev, struct device_attribute *attr,
+			  const char *buf, size_t size)
+{
+	struct usb_role_switch *sw = to_role_switch(dev);
+	int ret;
+
+	ret = sysfs_match_string(usb_roles, buf);
+	if (ret < 0) {
+		bool res;
+
+		/* Extra check if the user wants to disable the switch */
+		ret = kstrtobool(buf, &res);
+		if (ret || res)
+			return -EINVAL;
+	}
+
+	ret = usb_role_switch_set_role(sw, ret);
+	if (ret)
+		return ret;
+
+	return size;
+}
+static DEVICE_ATTR_RW(role);
+
+static struct attribute *usb_role_switch_attrs[] = {
+	&dev_attr_role.attr,
+	NULL,
+};
+
+static const struct attribute_group usb_role_switch_group = {
+	.is_visible = usb_role_switch_is_visible,
+	.attrs = usb_role_switch_attrs,
+};
+
+static const struct attribute_group *usb_role_switch_groups[] = {
+	&usb_role_switch_group,
+	NULL,
+};
+
+static int
+usb_role_switch_uevent(struct device *dev, struct kobj_uevent_env *env)
+{
+	int ret;
+
+	ret = add_uevent_var(env, "USB_ROLE_SWITCH=%s", dev_name(dev));
+	if (ret)
+		dev_err(dev, "failed to add uevent USB_ROLE_SWITCH\n");
+
+	return ret;
+}
+
+static void usb_role_switch_release(struct device *dev)
+{
+	struct usb_role_switch *sw = to_role_switch(dev);
+
+	kfree(sw);
+}
+
+static const struct device_type usb_role_dev_type = {
+	.name = "usb_role_switch",
+	.groups = usb_role_switch_groups,
+	.uevent = usb_role_switch_uevent,
+	.release = usb_role_switch_release,
+};
+
+/**
+ * usb_role_switch_register - Register USB Role Switch
+ * @parent: Parent device for the switch
+ * @desc: Description of the switch
+ *
+ * USB Role Switch is a device capable or choosing the role for USB connector.
+ * On platforms where the USB controller is dual-role capable, the controller
+ * driver will need to register the switch. On platforms where the USB host and
+ * USB device controllers behind the connector are separate, there will be a
+ * mux, and the driver for that mux will need to register the switch.
+ *
+ * Returns handle to a new role switch or ERR_PTR. The content of @desc is
+ * copied.
+ */
+struct usb_role_switch *
+usb_role_switch_register(struct device *parent,
+			 const struct usb_role_switch_desc *desc)
+{
+	struct usb_role_switch *sw;
+	int ret;
+
+	if (!desc || !desc->set)
+		return ERR_PTR(-EINVAL);
+
+	sw = kzalloc(sizeof(*sw), GFP_KERNEL);
+	if (!sw)
+		return ERR_PTR(-ENOMEM);
+
+	mutex_init(&sw->lock);
+
+	sw->allow_userspace_control = desc->allow_userspace_control;
+	sw->usb2_port = desc->usb2_port;
+	sw->usb3_port = desc->usb3_port;
+	sw->udc = desc->udc;
+	sw->set = desc->set;
+	sw->get = desc->get;
+
+	sw->dev.parent = parent;
+	sw->dev.class = role_class;
+	sw->dev.type = &usb_role_dev_type;
+	dev_set_name(&sw->dev, "%s-role-switch", dev_name(parent));
+
+	ret = device_register(&sw->dev);
+	if (ret) {
+		put_device(&sw->dev);
+		return ERR_PTR(ret);
+	}
+
+	/* TODO: Symlinks for the host port and the device controller. */
+
+	return sw;
+}
+EXPORT_SYMBOL_GPL(usb_role_switch_register);
+
+/**
+ * usb_role_switch_unregister - Unregsiter USB Role Switch
+ * @sw: USB Role Switch
+ *
+ * Unregister switch that was registered with usb_role_switch_register().
+ */
+void usb_role_switch_unregister(struct usb_role_switch *sw)
+{
+	if (!IS_ERR_OR_NULL(sw))
+		device_unregister(&sw->dev);
+}
+EXPORT_SYMBOL_GPL(usb_role_switch_unregister);
+
+static int __init usb_roles_init(void)
+{
+	role_class = class_create(THIS_MODULE, "usb_role");
+	return PTR_ERR_OR_ZERO(role_class);
+}
+subsys_initcall(usb_roles_init);
+
+static void __exit usb_roles_exit(void)
+{
+	class_destroy(role_class);
+}
+module_exit(usb_roles_exit);
+
+MODULE_AUTHOR("Heikki Krogerus <heikki.krogerus@linux.intel.com>");
+MODULE_AUTHOR("Hans de Goede <hdegoede@redhat.com>");
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("USB Role Class");