【linux字符设备驱动，带设备节点创建】

 

#include <linux/module.h> // module_init module_exit

#include <linux/init.h> // __init __exit

#include <linux/cdev.h>

#include <linux/fs.h>

#define MYNAME "chardev_test_longyh"

 

 

//DEVICE ID

dev_t devid;

static struct class *cls;

static struct device *test_device;

 

static int chardev_open(struct inode *inode, struct file *file)

{

printk(KERN_INFO "chardev open\n");

return 0;

}

 

static ssize_t chardev_read(struct file *file, char __user *buf,

size_t size, loff_t *ppos)

{

return 0;

}

 

 

static const struct file_operations chardev_fops = {

 

.open = chardev_open,

.read = chardev_read,

};

 

static struct

{

struct cdev cdev;

}chardev;

 

static int __init mymodule_init(void)

{

printk(KERN_INFO "chrdev_init helloworld init\n");

cdev_init(&chardev.cdev,&chardev_fops);

 

alloc_chrdev_region(&devid,2,1,MYNAME);

printk(KERN_INFO "MAJOR Number is %d\n",MAJOR(devid));

printk(KERN_INFO "MINOR Number is %d\n",MINOR(devid));

cdev_add(&chardev.cdev,devid,1);

cls = class_create(THIS_MODULE, MYNAME);

    if(IS_ERR(cls))

    {

cdev_del(&chardev.cdev);

unregister_chrdev_region(devid,1);

        return -EBUSY;

    }

test_device = device_create(cls,NULL,devid,NULL,MYNAME);//mknod /dev/hello

    if(IS_ERR(test_device))

    {

        class_destroy(cls);

cdev_del(&chardev.cdev);

unregister_chrdev_region(devid,1);

        return -EBUSY;

    }   

 

return 0;

}

static void __exit mymodule_exit(void)

{

printk(KERN_INFO "chrdev_exit helloworld exit\n");

cdev_del(&chardev.cdev);

unregister_chrdev_region(devid,1);

 

}

 

 

module_init(mymodule_init);

module_exit(mymodule_exit);

 

// MODULE_xxx这种宏作用是用来添加模块描述信息

MODULE_LICENSE("GPL"); // 描述模块的许可证

MODULE_AUTHOR("longyh"); // 描述模块的作者

MODULE_DESCRIPTION("module test"); // 描述模块的介绍信息

MODULE_ALIAS("alias xxx"); // 描述模块的别名信息