2018-2019-1 20165207 20165209 20165215 实验四外设驱动程序设计

实验内容和要求

1.外设驱动程序设计-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）
2.外设驱动程序设计-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（要多张，全屏，体现学号信息）

实验步骤

（一）康奈尔笔记

（二）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

按照书上要求，建立驱动代码源程序

   /*test_drv.c*/
  #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)
  {
      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.
");
      data = (char*)kmalloc(sizeof(char) * BUFF_SZ, GFP_KERNEL);
      if (!data)
      {
          return -ENOMEM;
      }
      return 0;
  }
  static int test_release(struct inode *inode, struct file *file)
  {
      printk("This is release operation.
");
      if (data)
      {
          kfree(data);
          data = NULL;
      }
      return 0;
  }
  static void test_setup_cdev(struct cdev *dev, int minor, struct file_operation *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);
      }
      if (result < 0)
      {
          printk(KERN_WARNING "Test device: unable to get major %d
",major);
          return result;
      }
      test_setup_cdev(&test_dev, 0, &test_fops);
      printk("The major of the test device is %d
", major);
      return 0;
  }
  void cleanup_module(void)
  {
      cdev_del(&test_dev);
      unregister_chrdev_region(MKDEV(major, 0), 1);
      printk("Test device uninstalled.
");
  }

Makefile文件

        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
  # 驱动模块名称
  module="test_drv"
  # 设备名称。在/proc/devices中出现
  device="test_dev"
  # 设备文件的属性
  mode="664"
  group="david"
  # 删除已存在的设备节点
  rm -f /dev/${device}
  # 加载驱动模块
  /sbin/insmod -f ./$module.ko $* || exit 1
  # 查到创建设备的主设备号
  major='cat /proc/devices | awk "\$2=="$device" {print \$1}"'
  # 创建设备文件节点
  mknod /dev/${device} c $major 0
  # 设备文件属性
  chgrp $group /dev/${device}
  chomd $mode /dev/${device}

test_drv_unload脚本

  # !/bin/sh
  module="test_drv"
  device="test_dev"
  # 卸载驱动模块
  /sbin/rmmod $module $* || exit 1
  # 删除设备文件
  rm -f /dev/${device}
  exit 0

测试代码test.c

      /* 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] = '';
          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
", buff);
          }
      } while(strncmp(buff, "quit", 4));
      close(fd);
      exit(0);
  }