int class_device_register(struct class_device *class_dev)
{
/* [cgw]: 初始化一个struct class_device */
class_device_initialize(class_dev);
/* [cgw]: 添加一个struct class_device */
return class_device_add(class_dev);
}
/**
* class_device_create - creates a class device and registers it with sysfs
* @cls: pointer to the struct class that this device should be registered to.
* @parent: pointer to the parent struct class_device of this new device, if any.
* @devt: the dev_t for the char device to be added.
* @device: a pointer to a struct device that is assiociated with this class device.
* @fmt: string for the class device's name
*
* This function can be used by char device classes. A struct
* class_device will be created in sysfs, registered to the specified
* class.
* A "dev" file will be created, showing the dev_t for the device, if
* the dev_t is not 0,0.
* If a pointer to a parent struct class_device is passed in, the newly
* created struct class_device will be a child of that device in sysfs.
* The pointer to the struct class_device will be returned from the
* call. Any further sysfs files that might be required can be created
* using this pointer.
*
* Note: the struct class passed to this function must have previously
* been created with a call to class_create().
*/
struct class_device *class_device_create(struct class *cls,
struct class_device *parent,
dev_t devt,
struct device *device,
const char *fmt, ...)
{
va_list args;
struct class_device *class_dev = NULL;
int retval = -ENODEV;
/* [cgw]: cls为空或错误 */
if (cls == NULL || IS_ERR(cls))
goto error;
/* [cgw]: 分配sizeof(*class_dev)字节大小的内存空间 */
class_dev = kzalloc(sizeof(*class_dev), GFP_KERNEL);
/* [cgw]: 分配失败 */
if (!class_dev) {
retval = -ENOMEM;
goto error;
}
/* [cgw]: 分配设备号 */
class_dev->devt = devt;
/* [cgw]: 分配一个struct device */
class_dev->dev = device;
/* [cgw]: 分配一个struct class */
class_dev->class = cls;
/* [cgw]: 分配一个parent struct class_device */
class_dev->parent = parent;
/* [cgw]: 分配release方法 */
class_dev->release = class_device_create_release;
/* [cgw]: 分配uevent方法 */
class_dev->uevent = class_device_create_uevent;
va_start(args, fmt);
/* [cgw]: 把args格式化到字符串fmt中，填装到class_dev->class_id */
vsnprintf(class_dev->class_id, BUS_ID_SIZE, fmt, args);
va_end(args);
/* [cgw]: 注册一个class_dev */
retval = class_device_register(class_dev);
if (retval)
goto error;
return class_dev;
error:
/* [cgw]: 释放class_dev的内存空间 */
kfree(class_dev);
return ERR_PTR(retval);
}
void class_device_del(struct class_device *class_dev)
{
struct class *parent_class = class_dev->class;
struct class_device *parent_device = class_dev->parent;
struct class_interface *class_intf;
/* [cgw]: parent_class不为空 */
if (parent_class) {
/* [cgw]: 获取信号量 */
down(&parent_class->sem);
/* [cgw]: 删除class_dev->node节点 */
list_del_init(&class_dev->node);
/* [cgw]: 历遍class_intf->node链表，直到回到parent_class->interfaces节点 */
list_for_each_entry(class_intf, &parent_class->interfaces, node)
/* [cgw]: class_intf->remove指针不为空 */
if (class_intf->remove)
/* [cgw]: 调用remove方法 */
class_intf->remove(class_dev, class_intf);
/* [cgw]: 释放信号量 */
up(&parent_class->sem);
}
/* [cgw]: class_dev->dev指针不为空 */
if (class_dev->dev) {
/* [cgw] : 从class_dev->dev->kobj对象目录下删除一个名字为
* class_dev->class->name+class_dev->kobj->k_name的链表
*/
remove_deprecated_class_device_links(class_dev);
/* [cgw]: class_dev->kobj目录下，删除名为device的链表 */
sysfs_remove_link(&class_dev->kobj, "device");
}
/* [cgw]: class_dev->kobj目录下，删除名为subsystem的链表 */
sysfs_remove_link(&class_dev->kobj, "subsystem");
/* [cgw]: 删除class_dev->kobj对象对应的一个class_dev->uevent_attr->attr
* 属性文件
*/
class_device_remove_file(class_dev, &class_dev->uevent_attr);
/* [cgw]: class_dev->devt_attr指针不为空 */
if (class_dev->devt_attr)
/* [cgw]: 删除class_dev->kobj对象对应的一个class_dev->devt_attr->attr
* 属性文件
*/
class_device_remove_file(class_dev, class_dev->devt_attr);
/* [cgw]: 历遍class_dev->class->class_dev_attrs[]数组，如果该属性名字不为空，
* 则对应地删除一个属性文件
*/
class_device_remove_attrs(class_dev);
/* [cgw]: 历遍class_dev->groups[]，删除所有属性组 */
class_device_remove_groups(class_dev);
/* [cgw]: 通知用户空间，产生一个KOBJ_REMOVE事件 */
kobject_uevent(&class_dev->kobj, KOBJ_REMOVE);
/* [cgw]: 删除kobj对象目录，从kset链表中删除class_dev->kobj */
kobject_del(&class_dev->kobj);
/* [cgw]: parent_device->kobj引用计数-1 */
class_device_put(parent_device);
/* [cgw]: parent_class->kobj引用计数-1 */
class_put(parent_class);
}
void class_device_unregister(struct class_device *class_dev)
{
pr_debug("CLASS: Unregistering class device. ID = '%s'\n",
class_dev->class_id);
/* [cgw]: 删除struct class_device */
class_device_del(class_dev);
/* [cgw]: class_dev->kobj引用计数-1 */
class_device_put(class_dev);
}
/**
* class_device_destroy - removes a class device that was created with class_device_create()
* @cls: the pointer to the struct class that this device was registered * with.
* @devt: the dev_t of the device that was previously registered.
*
* This call unregisters and cleans up a class device that was created with a
* call to class_device_create()
*/
void class_device_destroy(struct class *cls, dev_t devt)
{
struct class_device *class_dev = NULL;
struct class_device *class_dev_tmp;
/* [cgw]: 获得信号量 */
down(&cls->sem);
/* [cgw]: 返回class_dev_tmp指针，历遍class_dev_tmp链表，
* 查找与cls->children相等的节点class_dev_tmp->node
*/
list_for_each_entry(class_dev_tmp, &cls->children, node) {
/* [cgw]: 找到该节点，设备号为devt */
if (class_dev_tmp->devt == devt) {
/* [cgw]: class_dev指向class_dev_tmp */
class_dev = class_dev_tmp;
break;
}
}
/* [cgw]: 释放信号量 */
up(&cls->sem);
/* [cgw]: class_dev指针不为空 */
if (class_dev)
/* [cgw]: 注销这个class_dev */
class_device_unregister(class_dev);
}
struct class_device * class_device_get(struct class_device *class_dev)
{
/* [cgw]: class_dev指针不为空 */
if (class_dev)
/* [cgw]: class_dev->kobj引用计数+1
* 并根据kobj找到包含这个kobj的结构体指针
*/
return to_class_dev(kobject_get(&class_dev->kobj));
return NULL;
}
void class_device_put(struct class_device *class_dev)
{
/* [cgw]: class_dev指针不为空 */
if (class_dev)
/* [cgw]: class_dev->kobj引用计数-1 */
kobject_put(&class_dev->kobj);
}
int class_interface_register(struct class_interface *class_intf)
{
struct class *parent;
struct class_device *class_dev;
struct device *dev;
/* [cgw]: class_intf或class_intf->class指针为空 */
if (!class_intf || !class_intf->class)
return -ENODEV;
/* [cgw]: class_intf->class->subsys->kset.kobj引用计数+1，
* parent指向class_intf->class
*/
parent = class_get(class_intf->class);
/* [cgw]: parent指针为空 */
if (!parent)
return -EINVAL;
/* [cgw]: 获取信号量 */
down(&parent->sem);
/* [cgw]: 添加一个新节点class_intf->node，位于parent->interfaces节点前 */
list_add_tail(&class_intf->node, &parent->interfaces);
/* [cgw]: class_intf->add指针不为空 */
if (class_intf->add) {
/* [cgw]: 返回class_dev指针，历遍class_dev链表，
* 调用每个节点node对应的add方法
*/
list_for_each_entry(class_dev, &parent->children, node)
/* [cgw]: 调用与node (class_dev)对应的add方法 */
class_intf->add(class_dev, class_intf);
}
/* [cgw]: class_intf->add_dev指针不为空 */
if (class_intf->add_dev) {
/* [cgw]: 返回dev指针，历遍dev链表，
* 调用每个节点node对应的add_dev方法
*/
list_for_each_entry(dev, &parent->devices, node)
/* [cgw]: 调用与node (dev)对应的add_dev方法 */
class_intf->add_dev(dev, class_intf);
}
/* [cgw]: 释放信号量 */
up(&parent->sem);
return 0;
}
void class_interface_unregister(struct class_interface *class_intf)
{
/* [cgw]: parent指针指向class_intf->class */
struct class * parent = class_intf->class;
struct class_device *class_dev;
struct device *dev;
/* [cgw]: parent指针为空 */
if (!parent)
return;
/* [cgw]: 获取信号量 */
down(&parent->sem);
/* [cgw]: 删除一个节点class_intf->node */
list_del_init(&class_intf->node);
/* [cgw]: class_intf->remove指针不为空 */
if (class_intf->remove) {
/* [cgw]: 返回class_dev指针，历遍class_dev链表，
* 调用每个节点node对应的remove方法
*/
list_for_each_entry(class_dev, &parent->children, node)
/* [cgw]: 调用与node (class_dev)对应的remove方法 */
class_intf->remove(class_dev, class_intf);
}
/* [cgw]: class_intf->remove_dev指针不为空 */
if (class_intf->remove_dev) {
/* [cgw]: 返回dev指针，历遍dev链表，
* 调用每个节点node对应的remove_dev方法
*/
list_for_each_entry(dev, &parent->devices, node)
/* [cgw]: 调用与node (class_dev)对应的remove_dev方法 */
class_intf->remove_dev(dev, class_intf);
}
/* [cgw]: 释放信号量 */
up(&parent->sem);
/* [cgw]: parent->subsys->kobj引用计数-1 */
class_put(parent);
}
int __init classes_init(void)
{
int retval;
retval = subsystem_register(&class_subsys);
if (retval)
return retval;
/* ick, this is ugly, the things we go through to keep from showing up
* in sysfs... */
subsystem_init(&class_obj_subsys);
if (!class_obj_subsys.kobj.parent)
class_obj_subsys.kobj.parent = &class_obj_subsys.kobj;
return 0;
}
EXPORT_SYMBOL_GPL(class_create_file);
EXPORT_SYMBOL_GPL(class_remove_file);
EXPORT_SYMBOL_GPL(class_register);
EXPORT_SYMBOL_GPL(class_unregister);
EXPORT_SYMBOL_GPL(class_create);
EXPORT_SYMBOL_GPL(class_destroy);
EXPORT_SYMBOL_GPL(class_device_register);
EXPORT_SYMBOL_GPL(class_device_unregister);
EXPORT_SYMBOL_GPL(class_device_initialize);
EXPORT_SYMBOL_GPL(class_device_add);
EXPORT_SYMBOL_GPL(class_device_del);
EXPORT_SYMBOL_GPL(class_device_get);
EXPORT_SYMBOL_GPL(class_device_put);
EXPORT_SYMBOL_GPL(class_device_create);
EXPORT_SYMBOL_GPL(class_device_destroy);
EXPORT_SYMBOL_GPL(class_device_create_file);
EXPORT_SYMBOL_GPL(class_device_remove_file);
EXPORT_SYMBOL_GPL(class_device_create_bin_file);
EXPORT_SYMBOL_GPL(class_device_remove_bin_file);
EXPORT_SYMBOL_GPL(class_interface_register);
EXPORT_SYMBOL_GPL(class_interface_unregister);
