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 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 } 87 EXPORT_SYMBOL(mdev_register_parent); 88 89 /* 90 * mdev_unregister_parent : Unregister a parent device 91 * @parent: parent structure to unregister 92 */ 93 void 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 } 108 EXPORT_SYMBOL(mdev_unregister_parent); 109 110 static 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 } 127 128 int 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 because 148 * 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; 203 204 out_del: 205 device_del(&mdev->dev); 206 out_unlock: 207 up_read(&parent->unreg_sem); 208 out_put_device: 209 put_device(&mdev->dev); 210 return ret; 211 } 212 213 int 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 } 245 246 static 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 } 262 263 static void __exit mdev_exit(void) 264 { 265 class_compat_unregister(mdev_bus_compat_class); 266 bus_unregister(&mdev_bus_type); 267 } 268 269 subsys_initcall(mdev_init) 270 module_exit(mdev_exit) 271 272 MODULE_VERSION(DRIVER_VERSION); 273 MODULE_LICENSE("GPL v2"); 274 MODULE_AUTHOR(DRIVER_AUTHOR); 275 MODULE_DESCRIPTION(DRIVER_DESC); 276