# 2017-2018-1 20155332 实验四 外设驱动程序设计

2017-2018-1 20155332 实验四 外设驱动程序设计

实验目的

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
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

实验步骤

1.阅读hqyj.嵌入式Linux应用程序开发标准教程.pdf中的十一章，记录学习笔记。
笔记照片已经在蓝墨云班课提交
2.在VMware虚拟机中创建文件夹
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

3.根据书第十一章最后关于字符设备的test实验中代码，将test_drv.c，test.c，Makefile，test_drv_load，test_drv_unload文件敲入，保存在文件夹内。

截图见蓝墨云班课

书上代码如下：
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

#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_loa