| // 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) |
| { |
| struct usb_role_switch *sw; |
| |
| sw = device_connection_find_match(dev, "usb-role-switch", NULL, |
| usb_role_switch_match); |
| |
| if (!IS_ERR_OR_NULL(sw)) |
| WARN_ON(!try_module_get(sw->dev.parent->driver->owner)); |
| |
| return sw; |
| } |
| 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); |
| module_put(sw->dev.parent->driver->owner); |
| } |
| } |
| 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"); |