Linux字符设备驱动

/*Linux字符设备驱动源代码scdd.c*/#include <linux/init.h> /*模块头文件*/#include <linux/module.h>#include <linux/types.h> /*dev_t头文件*/#include <linux/kdev_t.h> /*MAJOR和MINOR宏头文件*/#include <linux/fs.h> /*register_chrdev_region等函数 file_operations结构体*/#include <linux/cdev.h> /*struct cdev结构体*/#include <asm/uaccess.h> /*copy_to_user函数*/ #define DEVICE_NAME "scdd" /*定义设备名*/#define DEVICE_MAJOR 250 struct cdev my_cdev; int scdd_open（struct inode *inode,structfile *filp）{ return0; }int scdd_close（struct inode *inode,structfile *filp）{ return0; }ssize_t scdd_read（struct file *filp,char__user *buff,size_t size,loff_t *offp）{ intleft; chardata=1; for（left=size;left>0;left--） { /*拷贝数据到用户空间*/ copy_to_user（buff,&data,1）; buff++; } returnsize;}ssize_t scdd_write（struct file *filp,char__user *buff,size_t size,loff_t *offp）{ return0;}/*file_operations结构体*/struct file_operations scdd_fops={ .owner=THIS_MODULE, .read=scdd_read, .write=scdd_write, .open=scdd_open, .release=scdd_close,};static int __init scdd_init（void）{ /*模块初始化函数*/ intsmajor; smajor=DEVICE_MAJOR; dev_tdev_n=MKDEV（smajor,0）; /*申请设备号*/ if（！register_chrdev_region（dev_n,1,DEVICE_NAME）） { /*静态申请*/ printk（"registersuccess "）; }else { gotoregister_error; } /*else { /*动态申请*/ /*alloc_chrdev_region（&dev_n,0,1,DEVICE_NAME）; smajor=MAJOR（dev_n）; }*/ /*初始化cdev结构体*/ cdev_init（&my_cdev,&scdd_fops）; my_cdev.owner=THIS_MODULE; my_cdev.ops=&scdd_fops; /*注册字符设备*/ cdev_add（&my_cdev,dev_n,1）; return0; register_error: unregister_chrdev_region（MKDEV（DEVICE_MAJOR,0）,1）; return0;}static void __exit scdd_exit（void）{ /*模块卸载函数*/ cdev_del（&my_cdev）; unregister_chrdev_region（MKDEV（DEVICE_MAJOR,0）,1）;} module_init（scdd_init）;module_exit（scdd_exit）;MODULE_LICENSE（"Dual BSD/GPL"）;
这个程序只是简单演示字符注册的一个完整过程，并不带有复杂的操作，调用read时向用户空间写全1