2017-2018-1 20155329 实验四 外设驱动程序设计

2017-2018-1 20155329 实验四 外设驱动程序设计

实验目的

任务一

实验要求


实验截图

#### 任务二

关于代码

本部分就是敲代码，理解最基础的kernel编程，代码在PDF首页上。

注意一切都要在老师给的环境中进行。

实验代码如下

test_drv.c代码如下所示：

#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

static struct cdev test_dev;

unsigned int major =0;

static char *data = NULL;

/*º¯ÊýÉùÃ÷*/

static ssize_t test_read(struct file *file, char *buf, size_t count, loff_t *f_pos);

static ssize_t test_write(struct file *file,const char *buffer, size_t count,loff_t *f_pos);

static int test_open(struct inode *inode, struct file *file);

static int test_release(struct inode *inode,struct file *file);

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))

{

return -EFAULT;

}

return count;

}

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))

{

return -EFAULT;

}

return count;

}

static int test_open(struct inode *inode, struct file *file)

{

printk("This is open operation\n");

data = (char*)kmalloc(sizeof(char) * BUFF_SZ, GFP_KERNEL);

if (!data)

{

return -ENOMEM;

}

memset(data, 0, BUFF_SZ);

return 0;

}

static int test_release(struct inode *inode,struct file *file)

{

printk("This is release operation\n");

if (data)

{

kfree(data);

data = NULL;

}

return 0;

}

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);

}

}

static struct file_operations test_fops =

{

.owner   = THIS_MODULE,

.read    = test_read,

.write   = test_write,

.open    = test_open,

.release = test_release,

};

int init_module(void)

{

int result;

dev_t dev = MKDEV(major, 0);

if (major)

{

result = register_chrdev_region(dev, 1, TEST_DEVICE_NAME);

}

else

{

result = alloc_chrdev_region(&dev, 0, 1, TEST_DEVICE_NAME);

major = MAJOR(dev);

}

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;

}

void cleanup_module(void)

{

cdev_del(&test_dev);

unregister_chrdev_region(MKDEV(major, 0), 1);

printk("Test device uninstalled\n");

}

test.c代码如下：

#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/test_dev"

#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);

}

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_drv_load脚本：

#!/bin/sh
module="test_drv"
device="test_dev"
mode="664"
group="david"

# remove stale nodes
rm -f /dev/${device}

# invoke insmod with all arguments we got
# and use a pathname, as newer modutils don't look in . by default
/sbin/insmod -f ./$module.ko $* || exit 1

major=`cat /proc/devices | awk "\\$2==\"$device\" {print \\$1}"`

mknod /dev/${device} c $major 0

# give appropriate group/permissions
chgrp $group /dev/${device}
chmod $mode  /dev/${device}

test_drv_unload脚本

#!/bin/sh
module="test_drv"
device="test_dev"

# invoke rmmod with all arguments we got
/sbin/rmmod $module $* || exit 1

# remove nodes
rm -f /dev/${device}

exit 0

实验截图

加载模块

先给脚本文件增加可执行权限：chmod +x ./test_drv_load

再以管理员身份运行加载脚本：sudo ./test_drv_load

编译运行test.c

卸载模块

先给脚本文件增加可执行权限：chmod +x ./test_drv_unload

再以管理员身份运行加载脚本：sudo ./test_drv_unload

实验中遇见的错误

insmod: error inserting 'hello.ko': -1 Invalid module format

解决办法 在网上找到相关博客

问题2：运行load脚本出现错误“insmod: error inserting './test_drv.ko': -1 File exists

”

解决：重启电脑

实验中学到的知识

设备驱动程序概念

Linux对设备驱动的处理

字符设备驱动程序编写流程及GPIO驱动实例

块设备驱动程序的编写流程及

相关的重要数据结构

设备驱动程序的组成

proc文件系统

中断编程及按键驱动程序实例

简单虚拟设备驱动程序编写、编译、加载、卸载

查看内核打印信息

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