// 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");