2017-2018-1 20155211 实验四 外设驱动程序设计

实验步骤

4-1

  • 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)

4-2

  • 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(体现学号信息)
  • 实验代码

/* 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

static struct cdev test_dev;

unsigned int major =0;

static char *data = NULL;

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:
/* 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/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

#!/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

#!/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

截图

遇到的问题

  • 按照步骤运行时,Makefile文件出现了问题,后发现是格式问题。按照步骤运行时,Makefile文件出现了问题,后发现是格式问题。

posted on 2017-12-03 14:28  20155211  阅读(99)  评论(0编辑  收藏  举报