嵌入式实验六

实验六嵌入式设备驱动程序设计班级：计算机14-1 学号：140344123139 姓名：23223 成绩：一、实验目的1. 掌握设备驱动程序的基本框架结构；2. 掌握设备进入点的创建、查看、删除方法；3. 掌握设备驱动程序模块的加载、查看、卸载方法；4. 编写简单字符设备驱动程序，并测试运行。

二、实验内容1.编写一个字符设备驱动程序，可实现字符串的读、写操作，再编写一个调用该设备驱动程序功能接口(打开、关闭、读、写)的用户程序，测试该驱动程序是否能正常运行。

2.对上述驱动程序进行修改，实现设备的互斥访问(设备上锁)。

（1）编译（2）装载模块（3）创建设备进入点（4）测试驱动程序(5) 程序代码如下devDrv.c#include "linux/kernel.h"#include "linux/module.h"#include "linux/fs.h"#include "linux/init.h"#include "linux/types.h"#include "linux/errno.h"#include "linux/uaccess.h"#include "linux/kdev_t.h"#define MAX_SIZE 1024static int my_open(struct inode *inode, struct file *file);static int my_release(struct inode *inode, struct file *file);static ssize_t my_read(struct file *file, char __user *user, size_t t, loff_t *f); static ssize_t my_write(struct file *file, const char __user *user, size_t t, loff_t *f);static char message[MAX_SIZE] = "-------congratulations--------!";static int device_num = 0;//设备号static int counter = 0;//计数用static int mutex = 0;//互斥用static char* devName = "myDevice";//设备名struct file_operations pStruct ={ open:my_open, release:my_release, read:my_read, write:my_write, };/* 注册模块*/int init_module(){int ret;/* 函数中第一个参数是告诉系统，新注册的设备的主设备号由系统分配，* 第二个参数是新设备注册时的设备名字，* 第三个参数是指向file_operations的指针，* 当用设备号为0创建时，系统一个可以用的设备号创建模块*/ret = register_chrdev(0, devName, &pStruct);if (ret < 0){printk("regist failure!\n");return -1;}else{printk("the device has been registered!\n");device_num = ret;printk("<1>the virtual device's major number %d.\n", device_num);printk("<1>Or you can see it by using\n");printk("<1>------more /proc/devices-------\n");printk("<1>To talk to the driver,create a dev file with\n");printk("<1>------'mknod /dev/myDevice c %d 0'-------\n", device_num);printk("<1>Use \"rmmode\" to remove the module\n");return 0;}}/* 注销模块，函数名很特殊*/void cleanup_module(){unregister_chrdev(device_num, devName);printk("unregister it success!\n");}static int my_open(struct inode *inode, struct file *file){if(mutex)return -EBUSY;mutex = 1;//上锁printk("<1>main device : %d\n", MAJOR(inode->i_rdev));printk("<1>slave device : %d\n", MINOR(inode->i_rdev));printk("<1>%d times to call the device\n", ++counter);try_module_get(THIS_MODULE);return 0;}/* 每次使用完后会release */static int my_release(struct inode *inode, struct file *file){printk("Device released!\n");module_put(THIS_MODULE);mutex = 0;//开锁return 0;}static ssize_t my_read(struct file *file, char __user *user, size_t t, loff_t *f){if(copy_to_user(user,message,sizeof(message))){return -EFAULT;}return sizeof(message);}static ssize_t my_write(struct file *file, const char __user *user, size_t t, loff_t *f) {if(copy_from_user(message,user,sizeof(message))){return -EFAULT;}return sizeof(message);}测试程序test.c#include <sys/types.h>#include <sys/stat.h>#include <stdlib.h>#include <string.h>#include <stdio.h>#include <fcntl.h>#include <unistd.h>#define MAX_SIZE 1024int main(void){int fd;char buf[MAX_SIZE];char get[MAX_SIZE];char devName[20], dir[50] = "/dev/";system("ls /dev/");printf("Please input the device's name you wanna to use :");gets(devName);strcat(dir, devName);fd = open(dir, O_RDWR | O_NONBLOCK);if (fd != -1){read(fd, buf, sizeof(buf));printf("The device was inited with a string : %s\n", buf);/* 测试写*/printf("Please input a string :\n");gets(get);write(fd, get, sizeof(get));/* 测试读*/read(fd, buf, sizeof(buf));system("dmesg");printf("\nThe string in the device now is : %s\n", buf);close(fd);return 0;}else{printf("Device open failed\n");return -1;}}Makefile# If KERNELRELEASE is defined, we've been invoked from the# kernel build system and can use its language.ifeq ($(KERNELRELEASE),)# Assume the source tree is where the running kernel was built # You should set KERNELDIR in the environment if it's elsewhere KERNELDIR ?= /lib/modules/$(shell uname -r)/build# The current directory is passed to sub-makes as argumentPWD := $(shell pwd)modules:$(MAKE) -C $(KERNELDIR) M=$(PWD) modulesmodules_install:$(MAKE) -C $(KERNELDIR) M=$(PWD) modules_installclean:rm -rf *.o *~ core .depend .*.cmd *.ko *.mod.c .tmp_versions.PHONY: modules modules_install cleanelse# called from kernel build system: just declare what our modules areobj-m := devDrv.oendif三、实验总结这一次的实验主要是实现一个驱动程序，虽然之前上课时讲过相关知识，但实现起来还是有点难，好在最后有参考程序，终于完成了这次实验，虽然对程序还是有一些不懂得地方，但把主要的函数先弄懂就行了。