2019-2020 20175207- 20175235 实验四 外设驱动程序设计
20175207-20175235 实验四 外设驱动程序设计
20175207冷南
20175235泽仁拉措
目录:
任务详情
学习资源中全课中的“hqyj.嵌入式Linux应用程序开发标准教程.pdf”中的第十一章
提交康奈尔笔记的照片(可以多张)
![](https://img2018.cnblogs.com/blog/1592071/201911/1592071-20191128111432542-785301309.jpg)
![](https://img2018.cnblogs.com/blog/1592071/201911/1592071-20191128113203715-1564048585.jpg)
![](https://img2018.cnblogs.com/blog/1592071/201911/1592071-20191128113037214-362791208.jpg)
任务详情
在Ubuntu完成资源中全课中的“hqyj.嵌入式Linux应用程序开发标准教程.pdf”中的第十一章的test试验
提交编译,加载模块,卸载模块,测试运行的截图(要多张,全屏,体现学号信息)
- Makefile
ifeq ($(KERNELRELEASE),)
KERNELDIR ?= /lib/modules/$(shell uname -r)/build
PWD := $(shell pwd)
modules:
$(MAKE) -C $(KERNELDIR) M=$(PWD) modules
modules_install:
$(MAKE) -C $(KERNELDIR) M=$(PWD) modules_install
clean:
rm -rf *.o *~ core .depend .*.cmd *.ko *.mod.c .tmp_versions
.PHONY: modules modules_install clean
else
obj-m := test_drv.o
endif
- test.c
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
#include <fcntl.h>
#define TEST_DEVICE_FILENAME "/dev/stdout"
#define BUFF_SZ 1024
int main()
{
int fd,nwrite,nread;
char buff[BUFF_SZ];
fd = open(TEST_DEVICE_FILENAME, O_RDWR);
if(fd<0)
{
perror("open");
exit(1);
}
do
{
printf("Input some words to kernel(enter 'quit' to exit):");
memset(buff,0,BUFF_SZ);
if(fgets(buff,BUFF_SZ,stdin) == NULL)
{
perror("fgets");
break;
}
buff[strlen(buff) - 1] = '\0';
if(write(fd,buff,strlen(buff)) < 0)
{
perror("write");
break;
}
if(read(fd,buff,BUFF_SZ) < 0)
{
perror("read");
break;
}
else
{
printf("The read string is from kernel:%s\n",buff);
}
} while(strncmp(buff,"quit",4));
close(fd);
exit(0);
}
- test_drv.c
#include <linux/module.h>
#include <linux/init.h>
#include <linux/fs.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/cdev.h>
#include <asm/uaccess.h>
#define TEST_DEVICE_NAME "test_dev"
#define BUFF_SZ 1024
/*全局变量*/
static struct cdev test_dev;
unsigned int major =0;
static char *data = NULL;
/*读函数*/
static ssize_t test_read(struct file *file,
char *buf, size_t count, loff_t *f_pos)
{
int len;
if (count < 0 )
{
return -EINVAL;
}
len = strlen(data);
count = (len > count)?count:len;
if (copy_to_user(buf, data, count)) /* ?内核??的数????用户??*/
{
return -EFAULT;
}
return count;
}
/*写函数*/
static ssize_t test_write(struct file *file, const char *buffer,
size_t count, loff_t *f_pos)
{
if(count < 0)
{
return -EINVAL;
}
memset(data, 0, BUFF_SZ);
count = (BUFF_SZ > count)?count:BUFF_SZ;
if (copy_from_user(data, buffer, count)) /* 将用户缓冲的数据复制到内核空间*/
{
return -EFAULT;
}
return count;
}
/*打开函数*/
static int test_open(struct inode *inode, struct file *file)
{
printk("This is open operation\n");
/* 分配并初始化缓冲区*/
data = (char*)kmalloc(sizeof(char) * BUFF_SZ, GFP_KERNEL);
if (!data)
{
return -ENOMEM;
}
memset(data, 0, BUFF_SZ);
return 0;
}
/*关闭函数*/
static int test_release(struct inode *inode,struct file *file)
{
printk("This is release operation\n");
if (data)
{
kfree(data); /* 释放缓冲区*/
data = NULL; /* 防止出现野指针*/
}
return 0;
}
/* 创建、初始化字符设备,并且注册到系统*/
static void test_setup_cdev(struct cdev *dev, int minor,
struct file_operations *fops)
{
int err, devno = MKDEV(major, minor);
cdev_init(dev, fops);
dev->owner = THIS_MODULE;
dev->ops = fops;
err = cdev_add (dev, devno, 1);
if (err)
{
printk (KERN_NOTICE "Error %d adding test %d", err, minor);
}
}
/* 虚拟设备的 file_operations 结构 */
static struct file_operations test_fops =
{
.owner = THIS_MODULE,
.read = test_read,
.write = test_write,
.open = test_open,
.release = test_release,
};
/*模块注册入口*/
int init_module(void)
{
int result;
dev_t dev = MKDEV(major, 0);
if (major)
{/* 静态注册一个设备,设备号先前指定好,并设定设备名,用cat /proc/devices 来查看 */
result = register_chrdev_region(dev, 1, TEST_DEVICE_NAME);
}
else
{
result = alloc_chrdev_region(&dev, 0, 1, TEST_DEVICE_NAME);
}
if (result < 0)
{
printk(KERN_WARNING "Test device: unable to get major %d\n", major);
return result;
}
test_setup_cdev(&test_dev, 0, &test_fops);
printk("The major of the test device is %d\n", major);
return 0;
}
/*卸载模块*/
void cleanup_module(void)
{
cdev_del(&test_dev);
unregister_chrdev_region(MKDEV(major, 0), 1);
printk("Test device uninstalled\n");
}
-
命令行:
- 在虚拟设备驱动源码目录下编译并加载驱动模块
make clean;make
;./test_drv_load
- 编译并运行测试程序
gcc –o test test.c
;./test
- 卸载驱动程序
./test_drv_unload
- 在虚拟设备驱动源码目录下编译并加载驱动模块
-
测试结果
-
安装驱动后
-
卸载后
-
遇到的问题:
-
使用
make
命令编译代码时报错Makefile ...(行号) ... 遗漏分隔符...停止
解决方法:命令行前缺少Tab
反斜线后多了空格
配置文件vimrc中有set expandtab(使用空格代替制表符)
参考链接:makefile报错