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字符設備驅動框架編寫流程如下：

（1）創(chuàng)建并注冊設備號

1—創(chuàng)建設備號dev_t
        static int hello_major = 250; //主設備號
        static int hello_minor = 0; //次設備號
        dev_t devno = MKDEV(hello_major, hello_minor);

2—申請設備號
        ret = register_chrdev_region(devno, number_of_device, "hello");
        if (ret < 0) {
        printk("failed from register_chrdev_region\n");
        return ret;
        }

3—釋放設備號
        unregister_chrdev_region(devno, 1)；

（2）設置操作集合ops
        定義file_operations 
        struct file_operations hello_ops = {
        .owner = THIS_MODULE,
        };

（3）注冊字符設備結構體cdev
        1、定義 
        a、struct cdev cdev; ----推薦
        b、struct cdev *cdev;
        cdev = cdev_alloc();
        2、初始化
        cdev_init(&cdev, &hello_ops);
        cdev.owner = THIS_MODULES;
        3、字符設備注冊
        cdev_add(&cdev, devno, 1);
        4、字符設備的注銷
        cdev_del(&cdev);

程序如下：

#include < linux/module.h>
　　#include < linux/kernel.h>
　　#include < linux/init.h>
　　#include < linux/fs.h>
　　#include < linux/cdev.h>
　　MODULE_LICENSE ("GPL");
　　int hello_major = 250;
　　int hello_minor = 0;
　　int number_of_devices = 1;
　　struct cdev cdev;
　　dev_t dev = 0;
　　struct file_operations hello_fops = {
　　 .owner = THIS_MODULE
　　};
　　static void char_reg_setup_cdev (void)
　　{
　　int error, devno = MKDEV (hello_major, hello_minor);
　　cdev_init (&cdev, &hello_fops);
　　cdev.owner = THIS_MODULE;
　　cdev.ops = &hello_fops;
　　error = cdev_add (&cdev, devno , 1);
　　if (error)
　　printk (KERN_NOTICE "Error %d adding char_reg_setup_cdev", error);
　　}
　　static int __init hello_2_init (void)
　　{
　　int result;
　　dev = MKDEV (hello_major, hello_minor);
　　result = register_chrdev_region (dev, number_of_devices, "hello");
　　if (result< 0) {
　　printk (KERN_WARNING "hello: can't get major number %d\n", hello_major);
　　return result;
　　}
　　char_reg_setup_cdev ();
　　printk (KERN_INFO "Registered character driver\n");
　　return 0;
　　}
　　static void __exit hello_2_exit (void)
　　{
　　dev_t devno = MKDEV (hello_major, hello_minor);
　　cdev_del (&cdev);
　　unregister_chrdev_region (devno, number_of_devices);
　　printk (KERN_INFO "char driver cleaned up\n");
　　}
　　module_init (hello_2_init);
　　module_exit (hello_2_exit);