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
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 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 */
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 device
91 * @parent: parent structure to unregister
92 */
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 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
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