1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Mediated device Core Driver 4 * 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 21 static struct class_compat *mdev_bus_compat_class; 22 23 static LIST_HEAD(mdev_list); 24 static DEFINE_MUTEX(mdev_list_lock); 25 26 /* Caller must hold parent unreg_sem read or write lock */ 27 static 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 38 static 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 mdevs 47 * @parent: parent structure registered 48 * @dev: device structure representing parent device. 49 * @mdev_driver: Device driver to bind to the newly created mdev 50 * @types: Array of supported mdev types 51 * @nr_types: Number of entries in @types 52 * 53 * Registers the @parent stucture as a parent for mdev types and thus mdev 54 * devices. The caller needs to hold a reference on @dev that must not be 55 * released until after the call to mdev_unregister_parent(). 56 * 57 * Returns a negative value on error, otherwise 0. 58 */ 59 int 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 if (!mdev_bus_compat_class) { 76 mdev_bus_compat_class = class_compat_register("mdev_bus"); 77 if (!mdev_bus_compat_class) 78 return -ENOMEM; 79 } 80 81 ret = parent_create_sysfs_files(parent); 82 if (ret) 83 return ret; 84 85 ret = class_compat_create_link(mdev_bus_compat_class, dev, NULL); 86 if (ret) 87 dev_warn(dev, "Failed to create compatibility class link\n"); 88 89 dev_info(dev, "MDEV: Registered\n"); 90 kobject_uevent_env(&dev->kobj, KOBJ_CHANGE, envp); 91 return 0; 92 } 93 EXPORT_SYMBOL(mdev_register_parent); 94 95 /* 96 * mdev_unregister_parent : Unregister a parent device 97 * @parent: parent structure to unregister 98 */ 99 void mdev_unregister_parent(struct mdev_parent *parent) 100 { 101 char *env_string = "MDEV_STATE=unregistered"; 102 char *envp[] = { env_string, NULL }; 103 104 dev_info(parent->dev, "MDEV: Unregistering\n"); 105 106 down_write(&parent->unreg_sem); 107 class_compat_remove_link(mdev_bus_compat_class, parent->dev, NULL); 108 device_for_each_child(parent->dev, NULL, mdev_device_remove_cb); 109 parent_remove_sysfs_files(parent); 110 up_write(&parent->unreg_sem); 111 112 kobject_uevent_env(&parent->dev->kobj, KOBJ_CHANGE, envp); 113 } 114 EXPORT_SYMBOL(mdev_unregister_parent); 115 116 static void mdev_device_release(struct device *dev) 117 { 118 struct mdev_device *mdev = to_mdev_device(dev); 119 struct mdev_parent *parent = mdev->type->parent; 120 121 mutex_lock(&mdev_list_lock); 122 list_del(&mdev->next); 123 if (!parent->mdev_driver->get_available) 124 atomic_inc(&parent->available_instances); 125 mutex_unlock(&mdev_list_lock); 126 127 /* Pairs with the get in mdev_device_create() */ 128 kobject_put(&mdev->type->kobj); 129 130 dev_dbg(&mdev->dev, "MDEV: destroying\n"); 131 kfree(mdev); 132 } 133 134 int mdev_device_create(struct mdev_type *type, const guid_t *uuid) 135 { 136 int ret; 137 struct mdev_device *mdev, *tmp; 138 struct mdev_parent *parent = type->parent; 139 struct mdev_driver *drv = parent->mdev_driver; 140 141 mutex_lock(&mdev_list_lock); 142 143 /* Check for duplicate */ 144 list_for_each_entry(tmp, &mdev_list, next) { 145 if (guid_equal(&tmp->uuid, uuid)) { 146 mutex_unlock(&mdev_list_lock); 147 return -EEXIST; 148 } 149 } 150 151 if (!drv->get_available) { 152 /* 153 * Note: that non-atomic read and dec is fine here because 154 * all modifications are under mdev_list_lock. 155 */ 156 if (!atomic_read(&parent->available_instances)) { 157 mutex_unlock(&mdev_list_lock); 158 return -EUSERS; 159 } 160 atomic_dec(&parent->available_instances); 161 } 162 163 mdev = kzalloc(sizeof(*mdev), GFP_KERNEL); 164 if (!mdev) { 165 mutex_unlock(&mdev_list_lock); 166 return -ENOMEM; 167 } 168 169 device_initialize(&mdev->dev); 170 mdev->dev.parent = parent->dev; 171 mdev->dev.bus = &mdev_bus_type; 172 mdev->dev.release = mdev_device_release; 173 mdev->dev.groups = mdev_device_groups; 174 mdev->type = type; 175 /* Pairs with the put in mdev_device_release() */ 176 kobject_get(&type->kobj); 177 178 guid_copy(&mdev->uuid, uuid); 179 list_add(&mdev->next, &mdev_list); 180 mutex_unlock(&mdev_list_lock); 181 182 ret = dev_set_name(&mdev->dev, "%pUl", uuid); 183 if (ret) 184 goto out_put_device; 185 186 /* Check if parent unregistration has started */ 187 if (!down_read_trylock(&parent->unreg_sem)) { 188 ret = -ENODEV; 189 goto out_put_device; 190 } 191 192 ret = device_add(&mdev->dev); 193 if (ret) 194 goto out_unlock; 195 196 ret = device_driver_attach(&drv->driver, &mdev->dev); 197 if (ret) 198 goto out_del; 199 200 ret = mdev_create_sysfs_files(mdev); 201 if (ret) 202 goto out_del; 203 204 mdev->active = true; 205 dev_dbg(&mdev->dev, "MDEV: created\n"); 206 up_read(&parent->unreg_sem); 207 208 return 0; 209 210 out_del: 211 device_del(&mdev->dev); 212 out_unlock: 213 up_read(&parent->unreg_sem); 214 out_put_device: 215 put_device(&mdev->dev); 216 return ret; 217 } 218 219 int mdev_device_remove(struct mdev_device *mdev) 220 { 221 struct mdev_device *tmp; 222 struct mdev_parent *parent = mdev->type->parent; 223 224 mutex_lock(&mdev_list_lock); 225 list_for_each_entry(tmp, &mdev_list, next) { 226 if (tmp == mdev) 227 break; 228 } 229 230 if (tmp != mdev) { 231 mutex_unlock(&mdev_list_lock); 232 return -ENODEV; 233 } 234 235 if (!mdev->active) { 236 mutex_unlock(&mdev_list_lock); 237 return -EAGAIN; 238 } 239 240 mdev->active = false; 241 mutex_unlock(&mdev_list_lock); 242 243 /* Check if parent unregistration has started */ 244 if (!down_read_trylock(&parent->unreg_sem)) 245 return -ENODEV; 246 247 mdev_device_remove_common(mdev); 248 up_read(&parent->unreg_sem); 249 return 0; 250 } 251 252 static int __init mdev_init(void) 253 { 254 return bus_register(&mdev_bus_type); 255 } 256 257 static void __exit mdev_exit(void) 258 { 259 if (mdev_bus_compat_class) 260 class_compat_unregister(mdev_bus_compat_class); 261 bus_unregister(&mdev_bus_type); 262 } 263 264 subsys_initcall(mdev_init) 265 module_exit(mdev_exit) 266 267 MODULE_VERSION(DRIVER_VERSION); 268 MODULE_LICENSE("GPL v2"); 269 MODULE_AUTHOR(DRIVER_AUTHOR); 270 MODULE_DESCRIPTION(DRIVER_DESC); 271