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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * Mediated device Core Driver4 *5 * Copyright (c) 2016, NVIDIA CORPORATION. All rights reserved.6 * Author: Neo Jia <cjia@nvidia.com>7 * Kirti Wankhede <kwankhede@nvidia.com>8 */9 10#include <linux/module.h>11#include <linux/slab.h>12#include <linux/sysfs.h>13#include <linux/mdev.h>14 15#include "mdev_private.h"16 17#define DRIVER_VERSION "0.1"18#define DRIVER_AUTHOR "NVIDIA Corporation"19#define DRIVER_DESC "Mediated device Core Driver"20 21static struct class_compat *mdev_bus_compat_class;22 23static LIST_HEAD(mdev_list);24static DEFINE_MUTEX(mdev_list_lock);25 26/* Caller must hold parent unreg_sem read or write lock */27static void mdev_device_remove_common(struct mdev_device *mdev)28{29 struct mdev_parent *parent = mdev->type->parent;30 31 mdev_remove_sysfs_files(mdev);32 device_del(&mdev->dev);33 lockdep_assert_held(&parent->unreg_sem);34 /* Balances with device_initialize() */35 put_device(&mdev->dev);36}37 38static int mdev_device_remove_cb(struct device *dev, void *data)39{40 if (dev->bus == &mdev_bus_type)41 mdev_device_remove_common(to_mdev_device(dev));42 return 0;43}44 45/*46 * mdev_register_parent: Register a device as parent for mdevs47 * @parent: parent structure registered48 * @dev: device structure representing parent device.49 * @mdev_driver: Device driver to bind to the newly created mdev50 * @types: Array of supported mdev types51 * @nr_types: Number of entries in @types52 *53 * Registers the @parent stucture as a parent for mdev types and thus mdev54 * devices. The caller needs to hold a reference on @dev that must not be55 * released until after the call to mdev_unregister_parent().56 *57 * Returns a negative value on error, otherwise 0.58 */59int mdev_register_parent(struct mdev_parent *parent, struct device *dev,60 struct mdev_driver *mdev_driver, struct mdev_type **types,61 unsigned int nr_types)62{63 char *env_string = "MDEV_STATE=registered";64 char *envp[] = { env_string, NULL };65 int ret;66 67 memset(parent, 0, sizeof(*parent));68 init_rwsem(&parent->unreg_sem);69 parent->dev = dev;70 parent->mdev_driver = mdev_driver;71 parent->types = types;72 parent->nr_types = nr_types;73 atomic_set(&parent->available_instances, mdev_driver->max_instances);74 75 ret = parent_create_sysfs_files(parent);76 if (ret)77 return ret;78 79 ret = class_compat_create_link(mdev_bus_compat_class, dev, NULL);80 if (ret)81 dev_warn(dev, "Failed to create compatibility class link\n");82 83 dev_info(dev, "MDEV: Registered\n");84 kobject_uevent_env(&dev->kobj, KOBJ_CHANGE, envp);85 return 0;86}87EXPORT_SYMBOL(mdev_register_parent);88 89/*90 * mdev_unregister_parent : Unregister a parent device91 * @parent: parent structure to unregister92 */93void mdev_unregister_parent(struct mdev_parent *parent)94{95 char *env_string = "MDEV_STATE=unregistered";96 char *envp[] = { env_string, NULL };97 98 dev_info(parent->dev, "MDEV: Unregistering\n");99 100 down_write(&parent->unreg_sem);101 class_compat_remove_link(mdev_bus_compat_class, parent->dev, NULL);102 device_for_each_child(parent->dev, NULL, mdev_device_remove_cb);103 parent_remove_sysfs_files(parent);104 up_write(&parent->unreg_sem);105 106 kobject_uevent_env(&parent->dev->kobj, KOBJ_CHANGE, envp);107}108EXPORT_SYMBOL(mdev_unregister_parent);109 110static void mdev_device_release(struct device *dev)111{112 struct mdev_device *mdev = to_mdev_device(dev);113 struct mdev_parent *parent = mdev->type->parent;114 115 mutex_lock(&mdev_list_lock);116 list_del(&mdev->next);117 if (!parent->mdev_driver->get_available)118 atomic_inc(&parent->available_instances);119 mutex_unlock(&mdev_list_lock);120 121 /* Pairs with the get in mdev_device_create() */122 kobject_put(&mdev->type->kobj);123 124 dev_dbg(&mdev->dev, "MDEV: destroying\n");125 kfree(mdev);126}127 128int mdev_device_create(struct mdev_type *type, const guid_t *uuid)129{130 int ret;131 struct mdev_device *mdev, *tmp;132 struct mdev_parent *parent = type->parent;133 struct mdev_driver *drv = parent->mdev_driver;134 135 mutex_lock(&mdev_list_lock);136 137 /* Check for duplicate */138 list_for_each_entry(tmp, &mdev_list, next) {139 if (guid_equal(&tmp->uuid, uuid)) {140 mutex_unlock(&mdev_list_lock);141 return -EEXIST;142 }143 }144 145 if (!drv->get_available) {146 /*147 * Note: that non-atomic read and dec is fine here because148 * all modifications are under mdev_list_lock.149 */150 if (!atomic_read(&parent->available_instances)) {151 mutex_unlock(&mdev_list_lock);152 return -EUSERS;153 }154 atomic_dec(&parent->available_instances);155 }156 157 mdev = kzalloc(sizeof(*mdev), GFP_KERNEL);158 if (!mdev) {159 mutex_unlock(&mdev_list_lock);160 return -ENOMEM;161 }162 163 device_initialize(&mdev->dev);164 mdev->dev.parent = parent->dev;165 mdev->dev.bus = &mdev_bus_type;166 mdev->dev.release = mdev_device_release;167 mdev->dev.groups = mdev_device_groups;168 mdev->type = type;169 /* Pairs with the put in mdev_device_release() */170 kobject_get(&type->kobj);171 172 guid_copy(&mdev->uuid, uuid);173 list_add(&mdev->next, &mdev_list);174 mutex_unlock(&mdev_list_lock);175 176 ret = dev_set_name(&mdev->dev, "%pUl", uuid);177 if (ret)178 goto out_put_device;179 180 /* Check if parent unregistration has started */181 if (!down_read_trylock(&parent->unreg_sem)) {182 ret = -ENODEV;183 goto out_put_device;184 }185 186 ret = device_add(&mdev->dev);187 if (ret)188 goto out_unlock;189 190 ret = device_driver_attach(&drv->driver, &mdev->dev);191 if (ret)192 goto out_del;193 194 ret = mdev_create_sysfs_files(mdev);195 if (ret)196 goto out_del;197 198 mdev->active = true;199 dev_dbg(&mdev->dev, "MDEV: created\n");200 up_read(&parent->unreg_sem);201 202 return 0;203 204out_del:205 device_del(&mdev->dev);206out_unlock:207 up_read(&parent->unreg_sem);208out_put_device:209 put_device(&mdev->dev);210 return ret;211}212 213int mdev_device_remove(struct mdev_device *mdev)214{215 struct mdev_device *tmp;216 struct mdev_parent *parent = mdev->type->parent;217 218 mutex_lock(&mdev_list_lock);219 list_for_each_entry(tmp, &mdev_list, next) {220 if (tmp == mdev)221 break;222 }223 224 if (tmp != mdev) {225 mutex_unlock(&mdev_list_lock);226 return -ENODEV;227 }228 229 if (!mdev->active) {230 mutex_unlock(&mdev_list_lock);231 return -EAGAIN;232 }233 234 mdev->active = false;235 mutex_unlock(&mdev_list_lock);236 237 /* Check if parent unregistration has started */238 if (!down_read_trylock(&parent->unreg_sem))239 return -ENODEV;240 241 mdev_device_remove_common(mdev);242 up_read(&parent->unreg_sem);243 return 0;244}245 246static int __init mdev_init(void)247{248 int ret;249 250 ret = bus_register(&mdev_bus_type);251 if (ret)252 return ret;253 254 mdev_bus_compat_class = class_compat_register("mdev_bus");255 if (!mdev_bus_compat_class) {256 bus_unregister(&mdev_bus_type);257 return -ENOMEM;258 }259 260 return 0;261}262 263static void __exit mdev_exit(void)264{265 class_compat_unregister(mdev_bus_compat_class);266 bus_unregister(&mdev_bus_type);267}268 269subsys_initcall(mdev_init)270module_exit(mdev_exit)271 272MODULE_VERSION(DRIVER_VERSION);273MODULE_LICENSE("GPL v2");274MODULE_AUTHOR(DRIVER_AUTHOR);275MODULE_DESCRIPTION(DRIVER_DESC);276