new file mode 100644
@@ -0,0 +1,21 @@
+What: /sys/class/usb_role/
+Date: Jan 2018
+Contact: Heikki Krogerus <heikki.krogerus@linux.intel.com>
+Description:
+ Place in sysfs for USB Role Switches. USB Role Switch is a
+ device that can select the data role (host or device) for USB
+ port.
+
+What: /sys/class/usb_role/<switch>/role
+Date: Jan 2018
+Contact: Heikki Krogerus <heikki.krogerus@linux.intel.com>
+Description:
+ The current role of the switch. This attribute can be used for
+ requesting role swapping with non-USB Type-C ports. With USB
+ Type-C ports, the ABI defined for USB Type-C connector class
+ must be used.
+
+ Valid values:
+ - none
+ - host
+ - device
@@ -197,4 +197,7 @@ config USB_ULPI_BUS
To compile this driver as a module, choose M here: the module will
be called ulpi.
+config USB_ROLE_SWITCH
+ tristate
+
endif # USB_SUPPORT
@@ -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
new file mode 100644
@@ -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/connection.h>
+#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 (!sw || IS_ERR(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 devcon *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_find_connection(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)
+ ret = size;
+
+ return ret;
+}
+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 (sw && !IS_ERR(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");
new file mode 100644
@@ -0,0 +1,51 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#ifndef __LINUX_USB_ROLE_H
+#define __LINUX_USB_ROLE_H
+
+struct usb_role_switch;
+
+enum usb_role {
+ USB_ROLE_NONE,
+ USB_ROLE_HOST,
+ USB_ROLE_DEVICE,
+};
+
+typedef int (*usb_role_switch_set_t)(struct device *dev, enum usb_role role);
+typedef enum usb_role (*usb_role_switch_get_t)(struct device *dev);
+
+/**
+ * struct usb_role_switch_desc - USB Role Switch Descriptor
+ * @usb2_port: Optional reference to the host controller port device (USB2)
+ * @usb3_port: Optional reference to the host controller port device (USB3)
+ * @udc: Optional reference to the peripheral controller device
+ * @set: Callback for setting the role
+ * @get: Callback for getting the role (optional)
+ * @allow_userspace_control: If true userspace may change the role through sysfs
+ *
+ * @usb2_port and @usb3_port will point to the USB host port and @udc to the USB
+ * device controller behind the USB connector with the role switch. If
+ * @usb2_port, @usb3_port and @udc are included in the description, the
+ * reference count for them should be incremented by the caller of
+ * usb_role_switch_register() before registering the switch.
+ */
+struct usb_role_switch_desc {
+ 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;
+};
+
+int usb_role_switch_set_role(struct usb_role_switch *sw, enum usb_role role);
+enum usb_role usb_role_switch_get_role(struct usb_role_switch *sw);
+struct usb_role_switch *usb_role_switch_get(struct device *dev);
+void usb_role_switch_put(struct usb_role_switch *sw);
+
+struct usb_role_switch *
+usb_role_switch_register(struct device *parent,
+ const struct usb_role_switch_desc *desc);
+void usb_role_switch_unregister(struct usb_role_switch *sw);
+
+#endif /* __LINUX_USB_ROLE_H */