linux驱动自动添加设备节点

大概思路：

先在驱动初始化的代码里调用class_create(...)为该设备创建一个class

再为每个设备调用device_create(...)( 在2.6较早的内核中用class_device_create)创建对应的设备

驱动退出函数时先删除设备，再删除类

下面以一个简单字符设备驱动来展示如何使用这几个函数

#include <linux/module.h>

#include <linux/kernel.h>

#include <linux/init.h>

#include <linux/fs.h>

#include <linux/cdev.h>

#include <linux/device.h>

int HELLO_MAJOR = 210;

int HELLO_MINOR = 0;

int NUMBER_OF_DEVICES = 2;

struct class *my_class;

struct cdev cdev;

dev_t devno;

struct file_operations hello_fops = {

.owner = THIS_MODULE

};

static int __init hello_init (void)

{

int result;

devno = MKDEV(HELLO_MAJOR, HELLO_MINOR);

if (HELLO_MAJOR)

result = register_chrdev_region(devno, 2, "memdev");

else

{

result = alloc_chrdev_region(&devno, 0, 2, "memdev");

HELLO_MAJOR = MAJOR(devno);

}

printk("MAJOR IS %d\n",HELLO_MAJOR);

my_class = class_create(THIS_MODULE,"hello_char_class"); //类名为hello_char_class

if(IS_ERR(my_class))

{

printk("Err: failed in creating class.\n");

return -1;

}

device_create(my_class,NULL,devno,NULL,"memdev"); //设备名为memdev

if (result<0)

{

printk (KERN_WARNING "hello: can't get major number %d\n", HELLO_MAJOR);

return result;

}

cdev_init(&cdev, &hello_fops);

cdev.owner = THIS_MODULE;

cdev_add(&cdev, devno, NUMBER_OF_DEVICES);

printk (KERN_INFO "Character driver Registered\n");

return 0;

}

static void __exit hello_exit (void)

{

cdev_del (&cdev);

device_destroy(my_class, devno); //delete device node under 必须先删除设备，再删除class类

class_destroy(my_class); //delete class created by us

unregister_chrdev_region (devno,NUMBER_OF_DEVICES);

printk (KERN_INFO "char driver cleaned up\n");

}

module_init (hello_init);

module_exit (hello_exit);

MODULE_LICENSE ("GPL");