1 int class_device_register(struct class_device *class_dev)
2 {
3 /* [cgw]: 初始化一个struct class_device */
4 class_device_initialize(class_dev);
5 /* [cgw]: 添加一个struct class_device */
6 return class_device_add(class_dev);
7 }
8
9 /**
10 * class_device_create - creates a class device and registers it with sysfs
11 * @cls: pointer to the struct class that this device should be registered to.
12 * @parent: pointer to the parent struct class_device of this new device, if any.
13 * @devt: the dev_t for the char device to be added.
14 * @device: a pointer to a struct device that is assiociated with this class device.
15 * @fmt: string for the class device's name
16 *
17 * This function can be used by char device classes. A struct
18 * class_device will be created in sysfs, registered to the specified
19 * class.
20 * A "dev" file will be created, showing the dev_t for the device, if
21 * the dev_t is not 0,0.
22 * If a pointer to a parent struct class_device is passed in, the newly
23 * created struct class_device will be a child of that device in sysfs.
24 * The pointer to the struct class_device will be returned from the
25 * call. Any further sysfs files that might be required can be created
26 * using this pointer.
27 *
28 * Note: the struct class passed to this function must have previously
29 * been created with a call to class_create().
30 */
31 struct class_device *class_device_create(struct class *cls,
32 struct class_device *parent,
33 dev_t devt,
34 struct device *device,
35 const char *fmt, ...)
36 {
37 va_list args;
38 struct class_device *class_dev = NULL;
39 int retval = -ENODEV;
40
41 /* [cgw]: cls为空或错误 */
42 if (cls == NULL || IS_ERR(cls))
43 goto error;
44
45 /* [cgw]: 分配sizeof(*class_dev)字节大小的内存空间 */
46 class_dev = kzalloc(sizeof(*class_dev), GFP_KERNEL);
47 /* [cgw]: 分配失败 */
48 if (!class_dev) {
49 retval = -ENOMEM;
50 goto error;
51 }
52
53 /* [cgw]: 分配设备号 */
54 class_dev->devt = devt;
55 /* [cgw]: 分配一个struct device */
56 class_dev->dev = device;
57 /* [cgw]: 分配一个struct class */
58 class_dev->class = cls;
59 /* [cgw]: 分配一个parent struct class_device */
60 class_dev->parent = parent;
61 /* [cgw]: 分配release方法 */
62 class_dev->release = class_device_create_release;
63 /* [cgw]: 分配uevent方法 */
64 class_dev->uevent = class_device_create_uevent;
65
66 va_start(args, fmt);
67 /* [cgw]: 把args格式化到字符串fmt中，填装到class_dev->class_id */
68 vsnprintf(class_dev->class_id, BUS_ID_SIZE, fmt, args);
69 va_end(args);
70 /* [cgw]: 注册一个class_dev */
71 retval = class_device_register(class_dev);
72 if (retval)
73 goto error;
74
75 return class_dev;
76
77 error:
78 /* [cgw]: 释放class_dev的内存空间 */
79 kfree(class_dev);
80 return ERR_PTR(retval);
81 }
82
83 void class_device_del(struct class_device *class_dev)
84 {
85 struct class *parent_class = class_dev->class;
86 struct class_device *parent_device = class_dev->parent;
87 struct class_interface *class_intf;
88
89 /* [cgw]: parent_class不为空 */
90 if (parent_class) {
91 /* [cgw]: 获取信号量 */
92 down(&parent_class->sem);
93 /* [cgw]: 删除class_dev->node节点 */
94 list_del_init(&class_dev->node);
95 /* [cgw]: 历遍class_intf->node链表，直到回到parent_class->interfaces节点 */
96 list_for_each_entry(class_intf, &parent_class->interfaces, node)
97 /* [cgw]: class_intf->remove指针不为空 */
98 if (class_intf->remove)
99 /* [cgw]: 调用remove方法 */
100 class_intf->remove(class_dev, class_intf);
101 /* [cgw]: 释放信号量 */
102 up(&parent_class->sem);
103 }
104
105 /* [cgw]: class_dev->dev指针不为空 */
106 if (class_dev->dev) {
107 /* [cgw] : 从class_dev->dev->kobj对象目录下删除一个名字为
108 * class_dev->class->name+class_dev->kobj->k_name的链表
109 */
110 remove_deprecated_class_device_links(class_dev);
111 /* [cgw]: class_dev->kobj目录下，删除名为device的链表 */
112 sysfs_remove_link(&class_dev->kobj, "device");
113 }
114 /* [cgw]: class_dev->kobj目录下，删除名为subsystem的链表 */
115 sysfs_remove_link(&class_dev->kobj, "subsystem");
116
117 /* [cgw]: 删除class_dev->kobj对象对应的一个class_dev->uevent_attr->attr
118 * 属性文件
119 */
120 class_device_remove_file(class_dev, &class_dev->uevent_attr);
121 /* [cgw]: class_dev->devt_attr指针不为空 */
122 if (class_dev->devt_attr)
123 /* [cgw]: 删除class_dev->kobj对象对应的一个class_dev->devt_attr->attr
124 * 属性文件
125 */
126 class_device_remove_file(class_dev, class_dev->devt_attr);
127 /* [cgw]: 历遍class_dev->class->class_dev_attrs[]数组，如果该属性名字不为空，
128 * 则对应地删除一个属性文件
129 */
130 class_device_remove_attrs(class_dev);
131 /* [cgw]: 历遍class_dev->groups[]，删除所有属性组 */
132 class_device_remove_groups(class_dev);
133
134 /* [cgw]: 通知用户空间，产生一个KOBJ_REMOVE事件 */
135 kobject_uevent(&class_dev->kobj, KOBJ_REMOVE);
136 /* [cgw]: 删除kobj对象目录，从kset链表中删除class_dev->kobj */
137 kobject_del(&class_dev->kobj);
138
139 /* [cgw]: parent_device->kobj引用计数-1 */
140 class_device_put(parent_device);
141 /* [cgw]: parent_class->kobj引用计数-1 */
142 class_put(parent_class);
143 }
144
145 void class_device_unregister(struct class_device *class_dev)
146 {
147 pr_debug("CLASS: Unregistering class device. ID = '%s'\n",
148 class_dev->class_id);
149 /* [cgw]: 删除struct class_device */
150 class_device_del(class_dev);
151 /* [cgw]: class_dev->kobj引用计数-1 */
152 class_device_put(class_dev);
153 }
154
155 /**
156 * class_device_destroy - removes a class device that was created with class_device_create()
157 * @cls: the pointer to the struct class that this device was registered * with.
158 * @devt: the dev_t of the device that was previously registered.
159 *
160 * This call unregisters and cleans up a class device that was created with a
161 * call to class_device_create()
162 */
163 void class_device_destroy(struct class *cls, dev_t devt)
164 {
165 struct class_device *class_dev = NULL;
166 struct class_device *class_dev_tmp;
167
168 /* [cgw]: 获得信号量 */
169 down(&cls->sem);
170 /* [cgw]: 返回class_dev_tmp指针，历遍class_dev_tmp链表，
171 * 查找与cls->children相等的节点class_dev_tmp->node
172 */
173 list_for_each_entry(class_dev_tmp, &cls->children, node) {
174 /* [cgw]: 找到该节点，设备号为devt */
175 if (class_dev_tmp->devt == devt) {
176 /* [cgw]: class_dev指向class_dev_tmp */
177 class_dev = class_dev_tmp;
178 break;
179 }
180 }
181 /* [cgw]: 释放信号量 */
182 up(&cls->sem);
183
184 /* [cgw]: class_dev指针不为空 */
185 if (class_dev)
186 /* [cgw]: 注销这个class_dev */
187 class_device_unregister(class_dev);
188 }
189
190 struct class_device * class_device_get(struct class_device *class_dev)
191 {
192 /* [cgw]: class_dev指针不为空 */
193 if (class_dev)
194 /* [cgw]: class_dev->kobj引用计数+1
195 * 并根据kobj找到包含这个kobj的结构体指针
196 */
197 return to_class_dev(kobject_get(&class_dev->kobj));
198 return NULL;
199 }
200
201 void class_device_put(struct class_device *class_dev)
202 {
203 /* [cgw]: class_dev指针不为空 */
204 if (class_dev)
205 /* [cgw]: class_dev->kobj引用计数-1 */
206 kobject_put(&class_dev->kobj);
207 }
208
209
210 int class_interface_register(struct class_interface *class_intf)
211 {
212 struct class *parent;
213 struct class_device *class_dev;
214 struct device *dev;
215
216 /* [cgw]: class_intf或class_intf->class指针为空 */
217 if (!class_intf || !class_intf->class)
218 return -ENODEV;
219
220 /* [cgw]: class_intf->class->subsys->kset.kobj引用计数+1，
221 * parent指向class_intf->class
222 */
223 parent = class_get(class_intf->class);
224 /* [cgw]: parent指针为空 */
225 if (!parent)
226 return -EINVAL;
227
228 /* [cgw]: 获取信号量 */
229 down(&parent->sem);
230 /* [cgw]: 添加一个新节点class_intf->node，位于parent->interfaces节点前 */
231 list_add_tail(&class_intf->node, &parent->interfaces);
232
233 /* [cgw]: class_intf->add指针不为空 */
234 if (class_intf->add) {
235 /* [cgw]: 返回class_dev指针，历遍class_dev链表，
236 * 调用每个节点node对应的add方法
237 */
238 list_for_each_entry(class_dev, &parent->children, node)
239 /* [cgw]: 调用与node (class_dev)对应的add方法 */
240 class_intf->add(class_dev, class_intf);
241 }
242
243 /* [cgw]: class_intf->add_dev指针不为空 */
244 if (class_intf->add_dev) {
245 /* [cgw]: 返回dev指针，历遍dev链表，
246 * 调用每个节点node对应的add_dev方法
247 */
248 list_for_each_entry(dev, &parent->devices, node)
249 /* [cgw]: 调用与node (dev)对应的add_dev方法 */
250 class_intf->add_dev(dev, class_intf);
251 }
252 /* [cgw]: 释放信号量 */
253 up(&parent->sem);
254
255 return 0;
256 }
257
258 void class_interface_unregister(struct class_interface *class_intf)
259 {
260 /* [cgw]: parent指针指向class_intf->class */
261 struct class * parent = class_intf->class;
262 struct class_device *class_dev;
263 struct device *dev;
264
265 /* [cgw]: parent指针为空 */
266 if (!parent)
267 return;
268
269 /* [cgw]: 获取信号量 */
270 down(&parent->sem);
271 /* [cgw]: 删除一个节点class_intf->node */
272 list_del_init(&class_intf->node);
273 /* [cgw]: class_intf->remove指针不为空 */
274 if (class_intf->remove) {
275 /* [cgw]: 返回class_dev指针，历遍class_dev链表，
276 * 调用每个节点node对应的remove方法
277 */
278 list_for_each_entry(class_dev, &parent->children, node)
279 /* [cgw]: 调用与node (class_dev)对应的remove方法 */
280 class_intf->remove(class_dev, class_intf);
281 }
282
283 /* [cgw]: class_intf->remove_dev指针不为空 */
284 if (class_intf->remove_dev) {
285 /* [cgw]: 返回dev指针，历遍dev链表，
286 * 调用每个节点node对应的remove_dev方法
287 */
288 list_for_each_entry(dev, &parent->devices, node)
289 /* [cgw]: 调用与node (class_dev)对应的remove_dev方法 */
290 class_intf->remove_dev(dev, class_intf);
291 }
292 /* [cgw]: 释放信号量 */
293 up(&parent->sem);
294
295 /* [cgw]: parent->subsys->kobj引用计数-1 */
296 class_put(parent);
297 }
298
299 int __init classes_init(void)
300 {
301 int retval;
302
303 retval = subsystem_register(&class_subsys);
304 if (retval)
305 return retval;
306
307 /* ick, this is ugly, the things we go through to keep from showing up
308 * in sysfs... */
309 subsystem_init(&class_obj_subsys);
310 if (!class_obj_subsys.kobj.parent)
311 class_obj_subsys.kobj.parent = &class_obj_subsys.kobj;
312 return 0;
313 }
314
315 EXPORT_SYMBOL_GPL(class_create_file);
316 EXPORT_SYMBOL_GPL(class_remove_file);
317 EXPORT_SYMBOL_GPL(class_register);
318 EXPORT_SYMBOL_GPL(class_unregister);
319 EXPORT_SYMBOL_GPL(class_create);
320 EXPORT_SYMBOL_GPL(class_destroy);
321
322 EXPORT_SYMBOL_GPL(class_device_register);
323 EXPORT_SYMBOL_GPL(class_device_unregister);
324 EXPORT_SYMBOL_GPL(class_device_initialize);
325 EXPORT_SYMBOL_GPL(class_device_add);
326 EXPORT_SYMBOL_GPL(class_device_del);
327 EXPORT_SYMBOL_GPL(class_device_get);
328 EXPORT_SYMBOL_GPL(class_device_put);
329 EXPORT_SYMBOL_GPL(class_device_create);
330 EXPORT_SYMBOL_GPL(class_device_destroy);
331 EXPORT_SYMBOL_GPL(class_device_create_file);
332 EXPORT_SYMBOL_GPL(class_device_remove_file);
333 EXPORT_SYMBOL_GPL(class_device_create_bin_file);
334 EXPORT_SYMBOL_GPL(class_device_remove_bin_file);
335
336 EXPORT_SYMBOL_GPL(class_interface_register);
337 EXPORT_SYMBOL_GPL(class_interface_unregister);
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