2017-2018-1 20155239 实验四 外设驱动程序设计

2017-2018-1 20155239 实验四 外设驱动程序设计

任务一

实验要求

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

2）提交康奈尔笔记的照片

完成情况



任务二

实验要求

1）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

2）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）

实验目的

该实验是编写最简单的字符驱动程序，这里的设备也就是一段内存，实现简单的读写功能，并列出常用格式的Makefile以及驱动的加载和卸载脚本。读者可以熟悉字符设备驱动的整个编写流程

实验内容

该实验要求实现对虚拟设备（一段内存）的打开、关闭、读写的操作，并要通过编写测试程序来测试虚拟设备及其驱动运行是否正常。

完成情况

1.编写驱动程序源代码

 #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");
}



  #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);

}

 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

#!/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}
 
 #!/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