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/device.h>
12 #include <linux/slab.h>
13 #include <linux/uuid.h>
14 #include <linux/sysfs.h>
15 #include <linux/mdev.h>
16 
17 #include "mdev_private.h"
18 
19 #define DRIVER_VERSION		"0.1"
20 #define DRIVER_AUTHOR		"NVIDIA Corporation"
21 #define DRIVER_DESC		"Mediated device Core Driver"
22 
23 static LIST_HEAD(parent_list);
24 static DEFINE_MUTEX(parent_list_lock);
25 static struct class_compat *mdev_bus_compat_class;
26 
27 static LIST_HEAD(mdev_list);
28 static DEFINE_MUTEX(mdev_list_lock);
29 
mdev_parent_dev(struct mdev_device * mdev)30 struct device *mdev_parent_dev(struct mdev_device *mdev)
31 {
32 	return mdev->type->parent->dev;
33 }
34 EXPORT_SYMBOL(mdev_parent_dev);
35 
36 /*
37  * Return the index in supported_type_groups that this mdev_device was created
38  * from.
39  */
mdev_get_type_group_id(struct mdev_device * mdev)40 unsigned int mdev_get_type_group_id(struct mdev_device *mdev)
41 {
42 	return mdev->type->type_group_id;
43 }
44 EXPORT_SYMBOL(mdev_get_type_group_id);
45 
46 /*
47  * Used in mdev_type_attribute sysfs functions to return the index in the
48  * supported_type_groups that the sysfs is called from.
49  */
mtype_get_type_group_id(struct mdev_type * mtype)50 unsigned int mtype_get_type_group_id(struct mdev_type *mtype)
51 {
52 	return mtype->type_group_id;
53 }
54 EXPORT_SYMBOL(mtype_get_type_group_id);
55 
56 /*
57  * Used in mdev_type_attribute sysfs functions to return the parent struct
58  * device
59  */
mtype_get_parent_dev(struct mdev_type * mtype)60 struct device *mtype_get_parent_dev(struct mdev_type *mtype)
61 {
62 	return mtype->parent->dev;
63 }
64 EXPORT_SYMBOL(mtype_get_parent_dev);
65 
66 /* Should be called holding parent_list_lock */
__find_parent_device(struct device * dev)67 static struct mdev_parent *__find_parent_device(struct device *dev)
68 {
69 	struct mdev_parent *parent;
70 
71 	list_for_each_entry(parent, &parent_list, next) {
72 		if (parent->dev == dev)
73 			return parent;
74 	}
75 	return NULL;
76 }
77 
mdev_release_parent(struct kref * kref)78 void mdev_release_parent(struct kref *kref)
79 {
80 	struct mdev_parent *parent = container_of(kref, struct mdev_parent,
81 						  ref);
82 	struct device *dev = parent->dev;
83 
84 	kfree(parent);
85 	put_device(dev);
86 }
87 
88 /* Caller must hold parent unreg_sem read or write lock */
mdev_device_remove_common(struct mdev_device * mdev)89 static void mdev_device_remove_common(struct mdev_device *mdev)
90 {
91 	struct mdev_parent *parent = mdev->type->parent;
92 
93 	mdev_remove_sysfs_files(mdev);
94 	device_del(&mdev->dev);
95 	lockdep_assert_held(&parent->unreg_sem);
96 	/* Balances with device_initialize() */
97 	put_device(&mdev->dev);
98 }
99 
mdev_device_remove_cb(struct device * dev,void * data)100 static int mdev_device_remove_cb(struct device *dev, void *data)
101 {
102 	struct mdev_device *mdev = mdev_from_dev(dev);
103 
104 	if (mdev)
105 		mdev_device_remove_common(mdev);
106 	return 0;
107 }
108 
109 /*
110  * mdev_register_device : Register a device
111  * @dev: device structure representing parent device.
112  * @mdev_driver: Device driver to bind to the newly created mdev
113  *
114  * Add device to list of registered parent devices.
115  * Returns a negative value on error, otherwise 0.
116  */
mdev_register_device(struct device * dev,struct mdev_driver * mdev_driver)117 int mdev_register_device(struct device *dev, struct mdev_driver *mdev_driver)
118 {
119 	int ret;
120 	struct mdev_parent *parent;
121 	char *env_string = "MDEV_STATE=registered";
122 	char *envp[] = { env_string, NULL };
123 
124 	/* check for mandatory ops */
125 	if (!mdev_driver->supported_type_groups)
126 		return -EINVAL;
127 
128 	dev = get_device(dev);
129 	if (!dev)
130 		return -EINVAL;
131 
132 	mutex_lock(&parent_list_lock);
133 
134 	/* Check for duplicate */
135 	parent = __find_parent_device(dev);
136 	if (parent) {
137 		parent = NULL;
138 		ret = -EEXIST;
139 		goto add_dev_err;
140 	}
141 
142 	parent = kzalloc(sizeof(*parent), GFP_KERNEL);
143 	if (!parent) {
144 		ret = -ENOMEM;
145 		goto add_dev_err;
146 	}
147 
148 	kref_init(&parent->ref);
149 	init_rwsem(&parent->unreg_sem);
150 
151 	parent->dev = dev;
152 	parent->mdev_driver = mdev_driver;
153 
154 	if (!mdev_bus_compat_class) {
155 		mdev_bus_compat_class = class_compat_register("mdev_bus");
156 		if (!mdev_bus_compat_class) {
157 			ret = -ENOMEM;
158 			goto add_dev_err;
159 		}
160 	}
161 
162 	ret = parent_create_sysfs_files(parent);
163 	if (ret)
164 		goto add_dev_err;
165 
166 	ret = class_compat_create_link(mdev_bus_compat_class, dev, NULL);
167 	if (ret)
168 		dev_warn(dev, "Failed to create compatibility class link\n");
169 
170 	list_add(&parent->next, &parent_list);
171 	mutex_unlock(&parent_list_lock);
172 
173 	dev_info(dev, "MDEV: Registered\n");
174 	kobject_uevent_env(&dev->kobj, KOBJ_CHANGE, envp);
175 
176 	return 0;
177 
178 add_dev_err:
179 	mutex_unlock(&parent_list_lock);
180 	if (parent)
181 		mdev_put_parent(parent);
182 	else
183 		put_device(dev);
184 	return ret;
185 }
186 EXPORT_SYMBOL(mdev_register_device);
187 
188 /*
189  * mdev_unregister_device : Unregister a parent device
190  * @dev: device structure representing parent device.
191  *
192  * Remove device from list of registered parent devices. Give a chance to free
193  * existing mediated devices for given device.
194  */
195 
mdev_unregister_device(struct device * dev)196 void mdev_unregister_device(struct device *dev)
197 {
198 	struct mdev_parent *parent;
199 	char *env_string = "MDEV_STATE=unregistered";
200 	char *envp[] = { env_string, NULL };
201 
202 	mutex_lock(&parent_list_lock);
203 	parent = __find_parent_device(dev);
204 
205 	if (!parent) {
206 		mutex_unlock(&parent_list_lock);
207 		return;
208 	}
209 	dev_info(dev, "MDEV: Unregistering\n");
210 
211 	list_del(&parent->next);
212 	mutex_unlock(&parent_list_lock);
213 
214 	down_write(&parent->unreg_sem);
215 
216 	class_compat_remove_link(mdev_bus_compat_class, dev, NULL);
217 
218 	device_for_each_child(dev, NULL, mdev_device_remove_cb);
219 
220 	parent_remove_sysfs_files(parent);
221 	up_write(&parent->unreg_sem);
222 
223 	mdev_put_parent(parent);
224 
225 	/* We still have the caller's reference to use for the uevent */
226 	kobject_uevent_env(&dev->kobj, KOBJ_CHANGE, envp);
227 }
228 EXPORT_SYMBOL(mdev_unregister_device);
229 
mdev_device_release(struct device * dev)230 static void mdev_device_release(struct device *dev)
231 {
232 	struct mdev_device *mdev = to_mdev_device(dev);
233 
234 	/* Pairs with the get in mdev_device_create() */
235 	kobject_put(&mdev->type->kobj);
236 
237 	mutex_lock(&mdev_list_lock);
238 	list_del(&mdev->next);
239 	mutex_unlock(&mdev_list_lock);
240 
241 	dev_dbg(&mdev->dev, "MDEV: destroying\n");
242 	kfree(mdev);
243 }
244 
mdev_device_create(struct mdev_type * type,const guid_t * uuid)245 int mdev_device_create(struct mdev_type *type, const guid_t *uuid)
246 {
247 	int ret;
248 	struct mdev_device *mdev, *tmp;
249 	struct mdev_parent *parent = type->parent;
250 	struct mdev_driver *drv = parent->mdev_driver;
251 
252 	mutex_lock(&mdev_list_lock);
253 
254 	/* Check for duplicate */
255 	list_for_each_entry(tmp, &mdev_list, next) {
256 		if (guid_equal(&tmp->uuid, uuid)) {
257 			mutex_unlock(&mdev_list_lock);
258 			return -EEXIST;
259 		}
260 	}
261 
262 	mdev = kzalloc(sizeof(*mdev), GFP_KERNEL);
263 	if (!mdev) {
264 		mutex_unlock(&mdev_list_lock);
265 		return -ENOMEM;
266 	}
267 
268 	device_initialize(&mdev->dev);
269 	mdev->dev.parent  = parent->dev;
270 	mdev->dev.bus = &mdev_bus_type;
271 	mdev->dev.release = mdev_device_release;
272 	mdev->dev.groups = mdev_device_groups;
273 	mdev->type = type;
274 	/* Pairs with the put in mdev_device_release() */
275 	kobject_get(&type->kobj);
276 
277 	guid_copy(&mdev->uuid, uuid);
278 	list_add(&mdev->next, &mdev_list);
279 	mutex_unlock(&mdev_list_lock);
280 
281 	ret = dev_set_name(&mdev->dev, "%pUl", uuid);
282 	if (ret)
283 		goto out_put_device;
284 
285 	/* Check if parent unregistration has started */
286 	if (!down_read_trylock(&parent->unreg_sem)) {
287 		ret = -ENODEV;
288 		goto out_put_device;
289 	}
290 
291 	ret = device_add(&mdev->dev);
292 	if (ret)
293 		goto out_unlock;
294 
295 	ret = device_driver_attach(&drv->driver, &mdev->dev);
296 	if (ret)
297 		goto out_del;
298 
299 	ret = mdev_create_sysfs_files(mdev);
300 	if (ret)
301 		goto out_del;
302 
303 	mdev->active = true;
304 	dev_dbg(&mdev->dev, "MDEV: created\n");
305 	up_read(&parent->unreg_sem);
306 
307 	return 0;
308 
309 out_del:
310 	device_del(&mdev->dev);
311 out_unlock:
312 	up_read(&parent->unreg_sem);
313 out_put_device:
314 	put_device(&mdev->dev);
315 	return ret;
316 }
317 
mdev_device_remove(struct mdev_device * mdev)318 int mdev_device_remove(struct mdev_device *mdev)
319 {
320 	struct mdev_device *tmp;
321 	struct mdev_parent *parent = mdev->type->parent;
322 
323 	mutex_lock(&mdev_list_lock);
324 	list_for_each_entry(tmp, &mdev_list, next) {
325 		if (tmp == mdev)
326 			break;
327 	}
328 
329 	if (tmp != mdev) {
330 		mutex_unlock(&mdev_list_lock);
331 		return -ENODEV;
332 	}
333 
334 	if (!mdev->active) {
335 		mutex_unlock(&mdev_list_lock);
336 		return -EAGAIN;
337 	}
338 
339 	mdev->active = false;
340 	mutex_unlock(&mdev_list_lock);
341 
342 	/* Check if parent unregistration has started */
343 	if (!down_read_trylock(&parent->unreg_sem))
344 		return -ENODEV;
345 
346 	mdev_device_remove_common(mdev);
347 	up_read(&parent->unreg_sem);
348 	return 0;
349 }
350 
mdev_init(void)351 static int __init mdev_init(void)
352 {
353 	return bus_register(&mdev_bus_type);
354 }
355 
mdev_exit(void)356 static void __exit mdev_exit(void)
357 {
358 	if (mdev_bus_compat_class)
359 		class_compat_unregister(mdev_bus_compat_class);
360 	bus_unregister(&mdev_bus_type);
361 }
362 
363 subsys_initcall(mdev_init)
364 module_exit(mdev_exit)
365 
366 MODULE_VERSION(DRIVER_VERSION);
367 MODULE_LICENSE("GPL v2");
368 MODULE_AUTHOR(DRIVER_AUTHOR);
369 MODULE_DESCRIPTION(DRIVER_DESC);
370