2017-2018-1 20155327 實驗四 外設驅動程序設計
題目一
學習資源中全課中的“hqyj.嵌入式Linux應用程序開發標準教程.pdf”中的第十一章
提交康奈爾筆記的照片（可以多張）
題目二
在Ubuntu完成資源中全課中的“hqyj.嵌入式Linux應用程序開發標準教程.pdf”中的第十一章的test試驗
提交編譯，加載模塊，卸載模塊，測試運行的截圖（要多張，全屏，體現學號信息）
實驗過程
#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/*全局變量*/
static struct cdev test_dev;
unsigned int major =0;
static char *data = NULL;/*讀函數*/
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)) /* 將內核緩沖的數據拷貝到用戶空間*/{return -EFAULT;}return count;
}/*寫函數*/
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)) /* 將用戶緩沖的數據復制到內核空間*/{return -EFAULT;}return count;
}/*打開函數*/
static int test_open(struct inode *inode, struct file *file)
{printk("This is open operation\n");/* 分配并初始化緩沖區*/data = (char*)kmalloc(sizeof(char) * BUFF_SZ, GFP_KERNEL);if (!data){return -ENOMEM;}memset(data, 0, BUFF_SZ); return 0;
}/*關閉函數*/
static int test_release(struct inode *inode,struct file *file){printk("This is release operation\n");if (data){kfree(data); /* 釋放緩沖區*/data = NULL; /* 防止出現野指針 */}return 0;
}/* 創建、初始化字符設備，并且注冊到系統*/
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);}
}/* 虛擬設備的file_operations結構 */
static struct file_operations test_fops =
{.owner = THIS_MODULE,.read = test_read,.write = test_write,.open = test_open,.release = test_release,
};/*模塊注冊入口*/
int init_module(void)
{int result;dev_t dev = MKDEV(major, 0);if (major){/* 靜態注冊一個設備，設備號先前指定好，并設定設備名，用cat /proc/devices來查看 */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\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;
}/*卸載模塊*/
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" /* 設備文件名*/
#define BUFF_SZ 1024 /* 緩沖大小 */int main()
{int fd, nwrite, nread;char buff[BUFF_SZ]; /*緩沖區*//* 打開設備文件 */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) /* 向設備寫入數據 */{perror("write");break;}if (read(fd, buff, BUFF_SZ) < 0) /* 從設備讀取數據 */{perror("read");break;}else{printf("The read string is from kernel:%s\n", buff);}} while(strncmp(buff, "quit", 4));close(fd);exit(0);}
實驗截圖
實驗中遇到的問題及解決方法
- 實驗時遇到權限不夠時輸入sudo來以管理員身份運行
轉載于:https://www.cnblogs.com/l97----/p/7967948.html
總結
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