实验目的:
1.学习Linux环境下虚拟设备驱动程序的设计。
2.学习如何将字符设备挂载到Liunx中,
实验内容:
1.编写一个虚拟字符设备的驱动程序模块demo.c,编译并通过
2.将的到的设备模块挂载到Linux环境下。
3.编写测试程序test.c对字符设备模块进行测试。
4.卸载该模块。
- demo.c
#include <linux/module.h>
#include <linux/init.h>
#include <linux/kernel.h> /* printk() */
#include <linux/fs.h> /* everything... */
#include <linux/errno.h> /* error codes */
#include <linux/types.h> /* size_t */
#include <linux/proc_fs.h>
#include <linux/fcntl.h> /* O_ACCMODE */
#include <linux/poll.h> /* COPY_TO_USER */
#include <linux/version.h>
#if LINUX_VERSION_CODE > KERNEL_VERSION(3,3,0)
#include <asm/switch_to.h>
#else
#include<asm/system.h>
#endif
#define DEVICE_NAME "char"
#define demo_MAJOR 300
#define demo_MINOR 0
#define MAX_BUF_LEN 20
static char drv_buf[32];
static int char_open(struct inode * inode,struct file*file)
{
//MOD_INC_USE_COUNT;
sprintf(drv_buf,"device open sucess!\n");
printk("device open sucess!\n");
return 0;
}
static int char_release(struct inode *inode, struct file *filp) {
//MOD_DEC_USE_COUNT;
printk("device release\n");
return 0;
}
/********************************************************************/
static ssize_t char_read(struct file *filp, char *buffer, size_t count, loff_t *ppos) {
if(count > MAX_BUF_LEN)
count=MAX_BUF_LEN;
copy_to_user(buffer, drv_buf,count);
printk("user read data from driver\n");
return count;
}
static ssize_t char_write(struct file *filp,const char *buffer, size_t count, loff_t *ppos) {
copy_from_user(drv_buf , buffer, count);
printk("user write data to driver\n");
//your code here
return count;
}
/******************************************************************/
//现在的版本没有ioctl函数,用unlocked_ioctl代替
static int char_unlocked_ioctl(struct file *file,
unsigned int cmd, unsigned long arg)
{
switch(cmd){
case 1:{printk("ioctl runing \n");
printk("runing command 1 \n");
break;}
case 2:{printk("ioctl runing \n");
printk("runing command 2 \n");
break;}
default:
printk("error cmd number\n");break;
}
return 0;
}
/*******************************************************************/
static struct file_operations char_fops = {
owner: THIS_MODULE,
write: demo_write,
read: demo_read,
ioctl: demo_unloced_ioctl,//注意
open: demo_open,
release: demo_release,
};
static int __init char_init(void) {
int result;
//SET_MODULE_OWNER(&demo_fops);
result = register_chrdev(demo_MAJOR, "char", &char_fops);
if (result < 0) return result;
printk(DEVICE_NAME " initialized\n");
return 0;
}
//模块的出口函数
static void __exit demo_exit(void) {
unregister_chrdev(char_MAJOR, "char");
printk(DEVICE_NAME " unloaded\n");
}
module_init(demo_init);
module_exit(demo_exit);