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 */
mdev_device_remove_common(struct mdev_device * mdev)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
mdev_device_remove_cb(struct device * dev,void * data)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 */
mdev_register_parent(struct mdev_parent * parent,struct device * dev,struct mdev_driver * mdev_driver,struct mdev_type ** types,unsigned int nr_types)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 */
mdev_unregister_parent(struct mdev_parent * parent)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
mdev_device_release(struct device * dev)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
mdev_device_create(struct mdev_type * type,const guid_t * uuid)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
mdev_device_remove(struct mdev_device * mdev)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
mdev_init(void)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
mdev_exit(void)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