// SPDX-License-Identifier: GPL-2.0
/*
* USB Role Switch Support
*
* Copyright (C) 2018 Intel Corporation
* Author: Heikki Krogerus <[email protected]>
* Hans de Goede <[email protected]>
*/
#include <linux/component.h>
#include <linux/usb/role.h>
#include <linux/property.h>
#include <linux/device.h>
#include <linux/lockdep.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/slab.h>
static const struct class role_class = {
.name = "usb_role",
};
struct usb_role_switch {
struct device dev;
struct lock_class_key key;
struct mutex lock; /* device lock*/
struct module *module; /* the module this device depends on */
enum usb_role role;
bool registered;
/* 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)
static int connector_bind(struct device *dev, struct device *connector, void *data)
{
int ret;
ret = sysfs_create_link(&dev->kobj, &connector->kobj, "connector");
if (ret)
return ret;
ret = sysfs_create_link(&connector->kobj, &dev->kobj, "usb-role-switch");
if (ret)
sysfs_remove_link(&dev->kobj, "connector");
return ret;
}
static void connector_unbind(struct device *dev, struct device *connector, void *data)
{
sysfs_remove_link(&connector->kobj, "usb-role-switch");
sysfs_remove_link(&dev->kobj, "connector");
}
static const struct component_ops connector_ops = {
.bind = connector_bind,
.unbind = connector_unbind,
};
/**
* 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;
if (!sw->registered)
return -EOPNOTSUPP;
mutex_lock(&sw->lock);
ret = sw->set(sw, role);
if (!ret) {
sw->role = role;
kobject_uevent(&sw->dev.kobj, KOBJ_CHANGE);
}
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) || !sw->registered)
return USB_ROLE_NONE;
mutex_lock(&sw->lock);
if (sw->get)
role = sw->get(sw);
else
role = sw->role;
mutex_unlock(&sw->lock);
return role;
}
EXPORT_SYMBOL_GPL(usb_role_switch_get_role);
static void *usb_role_switch_match(const struct fwnode_handle *fwnode, const char *id,
void *data)
{
struct device *dev;
if (id && !fwnode_property_present(fwnode, id))
return NULL;
dev = class_find_device_by_fwnode(&role_class, fwnode);
return dev ? to_role_switch(dev) : ERR_PTR(-EPROBE_DEFER);
}
static struct usb_role_switch *
usb_role_switch_is_parent(struct fwnode_handle *fwnode)
{
struct fwnode_handle *parent = fwnode_get_parent(fwnode);
struct device *dev;
if (!fwnode_property_present(parent, "usb-role-switch")) {
fwnode_handle_put(parent);
return NULL;
}
dev = class_find_device_by_fwnode(&role_class, parent);
fwnode_handle_put(parent);
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 = usb_role_switch_is_parent(dev_fwnode(dev));
if (!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->module));
return sw;
}
EXPORT_SYMBOL_GPL(usb_role_switch_get);
/**
* fwnode_usb_role_switch_get - Find USB role switch linked with the caller
* @fwnode: The caller device node
*
* This is similar to the usb_role_switch_get() function above, but it searches
* the switch using fwnode instead of device entry.
*/
struct usb_role_switch *fwnode_usb_role_switch_get(struct fwnode_handle *fwnode)
{
struct usb_role_switch *sw;
sw = usb_role_switch_is_parent(fwnode);
if (!sw)
sw = fwnode_connection_find_match(fwnode, "usb-role-switch",
NULL, usb_role_switch_match);
if (!IS_ERR_OR_NULL(sw))
WARN_ON(!try_module_get(sw->module));
return sw;
}
EXPORT_SYMBOL_GPL(fwnode_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)) {
module_put(sw->module);
put_device(&sw->dev);
}
}
EXPORT_SYMBOL_GPL(usb_role_switch_put);
/**
* usb_role_switch_find_by_fwnode - Find USB role switch with its fwnode
* @fwnode: fwnode of the USB Role Switch
*
* Finds and returns role switch with @fwnode. The reference count for the
* found switch is incremented.
*/
struct usb_role_switch *
usb_role_switch_find_by_fwnode(const struct fwnode_handle *fwnode)
{
struct device *dev;
struct usb_role_switch *sw = NULL;
if (!fwnode)
return NULL;
dev = class_find_device_by_fwnode(&role_class, fwnode);
if (dev) {
sw = to_role_switch(dev);
WARN_ON(!try_module_get(sw->module));
}
return sw;
}
EXPORT_SYMBOL_GPL(usb_role_switch_find_by_fwnode);
static umode_t
usb_role_switch_is_visible(struct kobject *kobj, struct attribute *attr, int n)
{
struct device *dev = kobj_to_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",
};
const char *usb_role_string(enum usb_role role)
{
if (role < 0 || role >= ARRAY_SIZE(usb_roles))
return "unknown";
return usb_roles[role];
}
EXPORT_SYMBOL_GPL(usb_role_string);
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(const 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);
mutex_destroy(&sw->lock);
lockdep_unregister_key(&sw->key);
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);
lockdep_register_key(&sw->key);
mutex_init_with_key(&sw->lock, &sw->key);
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->module = parent->driver->owner;
sw->dev.parent = parent;
sw->dev.fwnode = desc->fwnode;
sw->dev.class = &role_class;
sw->dev.type = &usb_role_dev_type;
dev_set_drvdata(&sw->dev, desc->driver_data);
dev_set_name(&sw->dev, "%s-role-switch",
desc->name ? desc->name : dev_name(parent));
ret = device_register(&sw->dev);
if (ret) {
put_device(&sw->dev);
return ERR_PTR(ret);
}
if (dev_fwnode(&sw->dev)) {
ret = component_add(&sw->dev, &connector_ops);
if (ret)
dev_warn(&sw->dev, "failed to add component\n");
}
sw->registered = true;
/* 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))
return;
sw->registered = false;
if (dev_fwnode(&sw->dev))
component_del(&sw->dev, &connector_ops);
device_unregister(&sw->dev);
}
EXPORT_SYMBOL_GPL(usb_role_switch_unregister);
/**
* usb_role_switch_set_drvdata - Assign private data pointer to a switch
* @sw: USB Role Switch
* @data: Private data pointer
*/
void usb_role_switch_set_drvdata(struct usb_role_switch *sw, void *data)
{
dev_set_drvdata(&sw->dev, data);
}
EXPORT_SYMBOL_GPL(usb_role_switch_set_drvdata);
/**
* usb_role_switch_get_drvdata - Get the private data pointer of a switch
* @sw: USB Role Switch
*/
void *usb_role_switch_get_drvdata(struct usb_role_switch *sw)
{
return dev_get_drvdata(&sw->dev);
}
EXPORT_SYMBOL_GPL(usb_role_switch_get_drvdata);
static int __init usb_roles_init(void)
{
return class_register(&role_class);
}
subsys_initcall(usb_roles_init);
static void __exit usb_roles_exit(void)
{
class_unregister(&role_class);
}
module_exit(usb_roles_exit);
MODULE_AUTHOR("Heikki Krogerus <[email protected]>");
MODULE_AUTHOR("Hans de Goede <[email protected]>");
MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("USB Role Class");
Codebase Browser
linux