// 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/property.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_fwnode_match(struct device *dev, const void *fwnode)
{
        return dev_fwnode(dev) == fwnode;
}

static int switch_name_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;

        if (con->fwnode) {
                if (!fwnode_property_present(con->fwnode, con->id))
                        return NULL;

                dev = class_find_device(role_class, NULL, con->fwnode,
                                        switch_fwnode_match);
        } else {
                dev = class_find_device(role_class, NULL, con->endpoint[ep],
                                        switch_name_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.fwnode = desc->fwnode;
        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");