register_chrdev函数简单使用

register_chrdev函数网上介绍的文章比较多，就不概述了。

以下是例子。

#include<linux/module.h>
#include<linux/kernel.h>
#include<linux/init.h>
#include<linux/fs.h>
#include<linux/slab.h>
#include<linux/timer.h>
#include<linux/sched.h>
#include<linux/list.h>
#include<linux/interrupt.h>
#include<linux/cdev.h> //cdev_init() cdev_add() cdev_del()
#include<linux/types.h> //dev_t
#include<linux/kdev_t.h> //有两个宏获取主设备号和次设备号#include<linux/uaccess.h> //container_of
MODULE_AUTHOR("Tan xujia");
MODULE_LICENSE("Dual BSD/GPL");/*设备的操作方法*/
int
char_open(struct inode *inode, struct file *filp)
{printk("open\n");return 0;
}ssize_t
char_read(struct file *filp, char __user *buf, size_t count, loff_t *fpos)
{printk("read\n");return 0;
}ssize_t
char_write(struct file *filp, const char __user *buf, size_t count, loff_t *fpos)
{printk("write\n");return 1;
}int
char_release(struct inode *inode, struct file *filp)
{printk("release\n");return 0;
}struct file_operations char_fops = {.owner = THIS_MODULE,.read = char_read,.write = char_write,.open = char_open,.release = char_release,
};int megasas_mgmt_majorno;
static
int __init hello_init (void)
{int rval = register_chrdev(0, "megaraid_sas_ioctl", &char_fops);if (rval < 0) {printk(KERN_DEBUG "megasas: failed to open device node\n");return rval;}megasas_mgmt_majorno = rval; //返回值是主设备号printk("rval = %d\n", rval);return 0;
}static
void __exit hello_exit (void)
{unregister_chrdev(megasas_mgmt_majorno, "megaraid_sas_ioctl");
}module_init(hello_init);
module_exit(hello_exit);