// 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/slab.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 struct class_compat *mdev_bus_compat_class; static LIST_HEAD(mdev_list);static DEFINE_MUTEX(mdev_list_lock); /* 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; 	mdev_remove_sysfs_files(mdev);	device_del(&mdev->dev);	lockdep_assert_held(&parent->unreg_sem);	/* Balances with device_initialize() */	put_device(&mdev->dev);} static int mdev_device_remove_cb(struct device *dev, void *data){	if (dev->bus == &mdev_bus_type)		mdev_device_remove_common(to_mdev_device(dev));	return 0;} /* * mdev_register_parent: Register a device as parent for mdevs * @parent: parent structure registered * @dev: device structure representing parent device. * @mdev_driver: Device driver to bind to the newly created mdev * @types: Array of supported mdev types * @nr_types: Number of entries in @types * * Registers the @parent stucture as a parent for mdev types and thus mdev * devices.  The caller needs to hold a reference on @dev that must not be * released until after the call to mdev_unregister_parent(). * * Returns a negative value on error, otherwise 0. */int mdev_register_parent(struct mdev_parent *parent, struct device *dev,		struct mdev_driver *mdev_driver, struct mdev_type **types,		unsigned int nr_types){	char *env_string = "MDEV_STATE=registered";	char *envp[] = { env_string, NULL };	int ret; 	memset(parent, 0, sizeof(*parent));	init_rwsem(&parent->unreg_sem);	parent->dev = dev;	parent->mdev_driver = mdev_driver;	parent->types = types;	parent->nr_types = nr_types;	atomic_set(&parent->available_instances, mdev_driver->max_instances); 	ret = parent_create_sysfs_files(parent);	if (ret)		return ret; 	ret = class_compat_create_link(mdev_bus_compat_class, dev);	if (ret)		dev_warn(dev, "Failed to create compatibility class link\n"); 	dev_info(dev, "MDEV: Registered\n");	kobject_uevent_env(&dev->kobj, KOBJ_CHANGE, envp);	return 0;}EXPORT_SYMBOL(mdev_register_parent); /* * mdev_unregister_parent : Unregister a parent device * @parent: parent structure to unregister */void mdev_unregister_parent(struct mdev_parent *parent){	char *env_string = "MDEV_STATE=unregistered";	char *envp[] = { env_string, NULL }; 	dev_info(parent->dev, "MDEV: Unregistering\n"); 	down_write(&parent->unreg_sem);	class_compat_remove_link(mdev_bus_compat_class, parent->dev);	device_for_each_child(parent->dev, NULL, mdev_device_remove_cb);	parent_remove_sysfs_files(parent);	up_write(&parent->unreg_sem); 	kobject_uevent_env(&parent->dev->kobj, KOBJ_CHANGE, envp);}EXPORT_SYMBOL(mdev_unregister_parent); static void mdev_device_release(struct device *dev){	struct mdev_device *mdev = to_mdev_device(dev);	struct mdev_parent *parent = mdev->type->parent; 	mutex_lock(&mdev_list_lock);	list_del(&mdev->next);	if (!parent->mdev_driver->get_available)		atomic_inc(&parent->available_instances);	mutex_unlock(&mdev_list_lock); 	/* Pairs with the get in mdev_device_create() */	kobject_put(&mdev->type->kobj); 	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->mdev_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;		}	} 	if (!drv->get_available) {		/*		 * Note: that non-atomic read and dec is fine here because		 * all modifications are under mdev_list_lock.		 */		if (!atomic_read(&parent->available_instances)) {			mutex_unlock(&mdev_list_lock);			return -EUSERS;		}		atomic_dec(&parent->available_instances);	} 	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 = mdev_device_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;	} 	ret = device_add(&mdev->dev);	if (ret)		goto out_unlock; 	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_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 ret; 	ret = bus_register(&mdev_bus_type);	if (ret)		return ret; 	mdev_bus_compat_class = class_compat_register("mdev_bus");	if (!mdev_bus_compat_class) {		bus_unregister(&mdev_bus_type);		return -ENOMEM;	} 	return 0;} static void __exit mdev_exit(void){	class_compat_unregister(mdev_bus_compat_class);	bus_unregister(&mdev_bus_type);} subsys_initcall(mdev_init)module_exit(mdev_exit) MODULE_VERSION(DRIVER_VERSION);MODULE_LICENSE("GPL v2");MODULE_AUTHOR(DRIVER_AUTHOR);MODULE_DESCRIPTION(DRIVER_DESC);