file_operation

struct file_operations ***_ops={

 .owner =  THIS_MODULE,

 .llseek =  ***_llseek,

 .read =  ***_read,

 .write =  ***_write,

 .ioctl =  ***_ioctl,

 .open =  ***_open,

 .release = ***_release, 

};

loff_t (*llseek) (struct file * filp , loff_t  p,  int  orig);

ssize_t (*read) (struct file * filp, char __user * buffer, size_t    size , loff_t *  p);

ssize_t (*write) (struct file *  filp, const char __user *   buffer, size_t  count, loff_t * ppos);

int (*ioctl) (struct file *filp, unsigned int cmd, unsigned long arg);

int (*open) (struct inode * inode , struct file *  filp ) ;

int (*release) (struct inode *, struct file *);

unsigned long copy_to_user(void __user *to, const void *from, unsigned long n);

unsigned long copy_from_user(void * to, const void __user * from, unsigned long n);

void cdev_init(struct cdev *cdev, const struct file_operations *fops)

int alloc_chrdev_region(dev_t *dev,unsigned int firstminor,unsigned int count,char *name);

Firstminor : 通常为0; 

*dev:存放返回的设备号; 

int cdev_add(struct cdev* dev,dev_t num,unsigned int count)

num设备号 count设备数

void cdev_del(struct cdev *p)

引用 void unregister_chrdev_region(dev_t first, unsigned int count);

first为第一个设备号，count为申请的设备数量