// SPDX-License-Identifier: GPL-2.0-only
/*
 * Mediated device Core Driver
 *
 * Copyright (c) 2016, NVIDIA CORPORATION. All rights reserved.
 *     Author: Neo Jia <cjia@nvidia.com>
 *             Kirti Wankhede <kwankhede@nvidia.com>
 */

#include <linux/module.h>
#include <linux/device.h>
#include <linux/slab.h>
#include <linux/uuid.h>
#include <linux/sysfs.h>
#include <linux/mdev.h>

#include "mdev_private.h"

#define DRIVER_VERSION          "0.1"
#define DRIVER_AUTHOR           "NVIDIA Corporation"
#define DRIVER_DESC             "Mediated device Core Driver"

static LIST_HEAD(parent_list);
static DEFINE_MUTEX(parent_list_lock);
static struct class_compat *mdev_bus_compat_class;

static LIST_HEAD(mdev_list);
static DEFINE_MUTEX(mdev_list_lock);

struct device *mdev_parent_dev(struct mdev_device *mdev)
{
        return mdev->type->parent->dev;
}
EXPORT_SYMBOL(mdev_parent_dev);

/*
 * Return the index in supported_type_groups that this mdev_device was created
 * from.
 */
unsigned int mdev_get_type_group_id(struct mdev_device *mdev)
{
        return mdev->type->type_group_id;
}
EXPORT_SYMBOL(mdev_get_type_group_id);

/*
 * Used in mdev_type_attribute sysfs functions to return the index in the
 * supported_type_groups that the sysfs is called from.
 */
unsigned int mtype_get_type_group_id(struct mdev_type *mtype)
{
        return mtype->type_group_id;
}
EXPORT_SYMBOL(mtype_get_type_group_id);

/*
 * Used in mdev_type_attribute sysfs functions to return the parent struct
 * device
 */
struct device *mtype_get_parent_dev(struct mdev_type *mtype)
{
        return mtype->parent->dev;
}
EXPORT_SYMBOL(mtype_get_parent_dev);

/* Should be called holding parent_list_lock */
static struct mdev_parent *__find_parent_device(struct device *dev)
{
        struct mdev_parent *parent;

        list_for_each_entry(parent, &parent_list, next) {
                if (parent->dev == dev)
                        return parent;
        }
        return NULL;
}

void mdev_release_parent(struct kref *kref)
{
        struct mdev_parent *parent = container_of(kref, struct mdev_parent,
                                                  ref);
        struct device *dev = parent->dev;

        kfree(parent);
        put_device(dev);
}

/* Caller must hold parent unreg_sem read or write lock */
static void mdev_device_remove_common(struct mdev_device *mdev)
{
        struct mdev_parent *parent = mdev->type->parent;
        int ret;

        mdev_remove_sysfs_files(mdev);
        device_del(&mdev->dev);
        lockdep_assert_held(&parent->unreg_sem);
        if (parent->ops->remove) {
                ret = parent->ops->remove(mdev);
                if (ret)
                        dev_err(&mdev->dev, "Remove failed: err=%d\n", ret);
        }

        /* Balances with device_initialize() */
        put_device(&mdev->dev);
}

static int mdev_device_remove_cb(struct device *dev, void *data)
{
        struct mdev_device *mdev = mdev_from_dev(dev);

        if (mdev)
                mdev_device_remove_common(mdev);
        return 0;
}

/*
 * mdev_register_device : Register a device
 * @dev: device structure representing parent device.
 * @ops: Parent device operation structure to be registered.
 *
 * Add device to list of registered parent devices.
 * Returns a negative value on error, otherwise 0.
 */
int mdev_register_device(struct device *dev, const struct mdev_parent_ops *ops)
{
        int ret;
        struct mdev_parent *parent;
        char *env_string = "MDEV_STATE=registered";
        char *envp[] = { env_string, NULL };

        /* check for mandatory ops */
        if (!ops || !ops->supported_type_groups)
                return -EINVAL;
        if (!ops->device_driver && (!ops->create || !ops->remove))
                return -EINVAL;

        dev = get_device(dev);
        if (!dev)
                return -EINVAL;

        mutex_lock(&parent_list_lock);

        /* Check for duplicate */
        parent = __find_parent_device(dev);
        if (parent) {
                parent = NULL;
                ret = -EEXIST;
                goto add_dev_err;
        }

        parent = kzalloc(sizeof(*parent), GFP_KERNEL);
        if (!parent) {
                ret = -ENOMEM;
                goto add_dev_err;
        }

        kref_init(&parent->ref);
        init_rwsem(&parent->unreg_sem);

        parent->dev = dev;
        parent->ops = ops;

        if (!mdev_bus_compat_class) {
                mdev_bus_compat_class = class_compat_register("mdev_bus");
                if (!mdev_bus_compat_class) {
                        ret = -ENOMEM;
                        goto add_dev_err;
                }
        }

        ret = parent_create_sysfs_files(parent);
        if (ret)
                goto add_dev_err;

        ret = class_compat_create_link(mdev_bus_compat_class, dev, NULL);
        if (ret)
                dev_warn(dev, "Failed to create compatibility class link\n");

        list_add(&parent->next, &parent_list);
        mutex_unlock(&parent_list_lock);

        dev_info(dev, "MDEV: Registered\n");
        kobject_uevent_env(&dev->kobj, KOBJ_CHANGE, envp);

        return 0;

add_dev_err:
        mutex_unlock(&parent_list_lock);
        if (parent)
                mdev_put_parent(parent);
        else
                put_device(dev);
        return ret;
}
EXPORT_SYMBOL(mdev_register_device);

/*
 * mdev_unregister_device : Unregister a parent device
 * @dev: device structure representing parent device.
 *
 * Remove device from list of registered parent devices. Give a chance to free
 * existing mediated devices for given device.
 */

void mdev_unregister_device(struct device *dev)
{
        struct mdev_parent *parent;
        char *env_string = "MDEV_STATE=unregistered";
        char *envp[] = { env_string, NULL };

        mutex_lock(&parent_list_lock);
        parent = __find_parent_device(dev);

        if (!parent) {
                mutex_unlock(&parent_list_lock);
                return;
        }
        dev_info(dev, "MDEV: Unregistering\n");

        list_del(&parent->next);
        mutex_unlock(&parent_list_lock);

        down_write(&parent->unreg_sem);

        class_compat_remove_link(mdev_bus_compat_class, dev, NULL);

        device_for_each_child(dev, NULL, mdev_device_remove_cb);

        parent_remove_sysfs_files(parent);
        up_write(&parent->unreg_sem);

        mdev_put_parent(parent);

        /* We still have the caller's reference to use for the uevent */
        kobject_uevent_env(&dev->kobj, KOBJ_CHANGE, envp);
}
EXPORT_SYMBOL(mdev_unregister_device);

static void mdev_device_release(struct device *dev)
{
        struct mdev_device *mdev = to_mdev_device(dev);

        /* Pairs with the get in mdev_device_create() */
        kobject_put(&mdev->type->kobj);

        mutex_lock(&mdev_list_lock);
        list_del(&mdev->next);
        mutex_unlock(&mdev_list_lock);

        dev_dbg(&mdev->dev, "MDEV: destroying\n");
        kfree(mdev);
}

int mdev_device_create(struct mdev_type *type, const guid_t *uuid)
{
        int ret;
        struct mdev_device *mdev, *tmp;
        struct mdev_parent *parent = type->parent;
        struct mdev_driver *drv = parent->ops->device_driver;

        mutex_lock(&mdev_list_lock);

        /* Check for duplicate */
        list_for_each_entry(tmp, &mdev_list, next) {
                if (guid_equal(&tmp->uuid, uuid)) {
                        mutex_unlock(&mdev_list_lock);
                        return -EEXIST;
                }
        }

        mdev = kzalloc(sizeof(*mdev), GFP_KERNEL);
        if (!mdev) {
                mutex_unlock(&mdev_list_lock);
                return -ENOMEM;
        }

        device_initialize(&mdev->dev);
        mdev->dev.parent  = parent->dev;
        mdev->dev.bus = &mdev_bus_type;
        mdev->dev.release = mdev_device_release;
        mdev->dev.groups = parent->ops->mdev_attr_groups;
        mdev->type = type;
        /* Pairs with the put in mdev_device_release() */
        kobject_get(&type->kobj);

        guid_copy(&mdev->uuid, uuid);
        list_add(&mdev->next, &mdev_list);
        mutex_unlock(&mdev_list_lock);

        ret = dev_set_name(&mdev->dev, "%pUl", uuid);
        if (ret)
                goto out_put_device;

        /* Check if parent unregistration has started */
        if (!down_read_trylock(&parent->unreg_sem)) {
                ret = -ENODEV;
                goto out_put_device;
        }

        if (parent->ops->create) {
                ret = parent->ops->create(mdev);
                if (ret)
                        goto out_unlock;
        }

        ret = device_add(&mdev->dev);
        if (ret)
                goto out_remove;

        if (!drv)
                drv = &vfio_mdev_driver;
        ret = device_driver_attach(&drv->driver, &mdev->dev);
        if (ret)
                goto out_del;

        ret = mdev_create_sysfs_files(mdev);
        if (ret)
                goto out_del;

        mdev->active = true;
        dev_dbg(&mdev->dev, "MDEV: created\n");
        up_read(&parent->unreg_sem);

        return 0;

out_del:
        device_del(&mdev->dev);
out_remove:
        if (parent->ops->remove)
                parent->ops->remove(mdev);
out_unlock:
        up_read(&parent->unreg_sem);
out_put_device:
        put_device(&mdev->dev);
        return ret;
}

int mdev_device_remove(struct mdev_device *mdev)
{
        struct mdev_device *tmp;
        struct mdev_parent *parent = mdev->type->parent;

        mutex_lock(&mdev_list_lock);
        list_for_each_entry(tmp, &mdev_list, next) {
                if (tmp == mdev)
                        break;
        }

        if (tmp != mdev) {
                mutex_unlock(&mdev_list_lock);
                return -ENODEV;
        }

        if (!mdev->active) {
                mutex_unlock(&mdev_list_lock);
                return -EAGAIN;
        }

        mdev->active = false;
        mutex_unlock(&mdev_list_lock);

        /* Check if parent unregistration has started */
        if (!down_read_trylock(&parent->unreg_sem))
                return -ENODEV;

        mdev_device_remove_common(mdev);
        up_read(&parent->unreg_sem);
        return 0;
}

static int __init mdev_init(void)
{
        int rc;

        rc = mdev_bus_register();
        if (rc)
                return rc;
        rc = mdev_register_driver(&vfio_mdev_driver);
        if (rc)
                goto err_bus;
        return 0;
err_bus:
        mdev_bus_unregister();
        return rc;
}

static void __exit mdev_exit(void)
{
        mdev_unregister_driver(&vfio_mdev_driver);

        if (mdev_bus_compat_class)
                class_compat_unregister(mdev_bus_compat_class);

        mdev_bus_unregister();
}

subsys_initcall(mdev_init)
module_exit(mdev_exit)

MODULE_VERSION(DRIVER_VERSION);
MODULE_LICENSE("GPL v2");
MODULE_AUTHOR(DRIVER_AUTHOR);
MODULE_DESCRIPTION(DRIVER_DESC);