飛凌嵌入式ElfBoard ELF 1板卡-內(nèi)核空間與用戶(hù)空間的數(shù)據(jù)拷貝之獲取用戶(hù)空間數(shù)據(jù)

#define DEVICE_NAME "copy_form_user" ?// 設(shè)備名稱(chēng)

static char user_buffer[BUFFER_SIZE] = "";

static ssize_t device_write(struct file *file, const char __user *buffer, size_t length, loff_t *offset)

{

????????ssize_t bytes_written = 0;

// 在這里處理設(shè)備寫(xiě)入的操作

????????printk(KERN_INFO "This is device_write.n");

?

????????if (*offset >= BUFFER_SIZE)

????????????????return -ENOSPC;

?????????if (*offset + length > BUFFER_SIZE)

?????????????????length = BUFFER_SIZE - *offset;

?????????if (copy_from_user(user_buffer + *offset, buffer, length))

?????????????????return -EFAULT;

?????????*offset += length;

?????????bytes_written = length;

?????????printk(KERN_INFO "Received from user: %s", user_buffer);

?

?????????return bytes_written;

}

#include <linux/module.h> ??????// 包含模塊相關(guān)函數(shù)的頭文件

#include <linux/fs.h> ??????????// 包含文件系統(tǒng)相關(guān)函數(shù)的頭文件

#include <linux/uaccess.h> ?????// 包含用戶(hù)空間數(shù)據(jù)訪(fǎng)問(wèn)函數(shù)的頭文件

#include <linux/cdev.h> ????????//包含字符設(shè)備頭文件

#include <linux/device.h>

#include <linux/uaccess.h>

#define DEVICE_NAME "copy_form_user" ?// 設(shè)備名稱(chēng)

static dev_t dev_num; ??//分配的設(shè)備號(hào)

struct ?cdev my_cdev; ?????????//字符設(shè)備指針

int major; ?//主設(shè)備號(hào)

int minor; ?//次設(shè)備號(hào)

static struct class *my_class;

static struct device *my_device;

?

#define BUFFER_SIZE 1024

static char kernel_buffer[BUFFER_SIZE] = "Hello, User! This is kernel_buffer!";

static char user_buffer[BUFFER_SIZE] = "";

?

static int device_open(struct inode *inode, struct file *file)

{

// 在這里處理設(shè)備打開(kāi)的操作

printk(KERN_INFO "This is device_open.n");

????return 0;

}

?

static int device_release(struct inode *inode, struct file *file)

{

// 在這里處理設(shè)備關(guān)閉的操作

printk(KERN_INFO "This is device_release.n");

????return 0;

}

static ssize_t device_read(struct file *file, char __user *buffer, size_t length, loff_t *offset)

{

????????ssize_t bytes_read = 0;

// 在這里處理設(shè)備讀取的操作

????????printk(KERN_INFO "This is device_read.n");

?

????????if (*offset >= BUFFER_SIZE)

????????????????return 0;

????????if (*offset + length > BUFFER_SIZE)

????????????????length = BUFFER_SIZE - *offset;

????????if (copy_to_user(buffer, kernel_buffer + *offset, length))

????????????????return -EFAULT;

????????*offset += length;

????????bytes_read = length;

????????return bytes_read;

?

?

}

?

static ssize_t device_write(struct file *file, const char __user *buffer, size_t length, loff_t *offset)

{

???ssize_t bytes_written = 0;

?

// 在這里處理設(shè)備寫(xiě)入的操作

????????printk(KERN_INFO "This is device_write.n");

?

????????if (*offset >= BUFFER_SIZE)

????????????????return -ENOSPC;

?????????if (*offset + length > BUFFER_SIZE)

?????????????????length = BUFFER_SIZE - *offset;

?????????if (copy_from_user(user_buffer + *offset, buffer, length))

?????????????????return -EFAULT;

?????????*offset += length;

?????????bytes_written = length;

?????????printk(KERN_INFO "Received from user: %s", user_buffer);

?

?????????return bytes_written;

}

?

static struct file_operations fops = {

????.owner = THIS_MODULE,

????.open = device_open,

????.release = device_release,

????.read = device_read,

????.write = device_write,

};

static int __init mydevice_init(void)

{

????int ret;

?

????// 在這里執(zhí)行驅(qū)動(dòng)程序的初始化操作

?

????// 注冊(cè)字符設(shè)備驅(qū)動(dòng)程序

????ret = alloc_chrdev_region(&dev_num,0,1,DEVICE_NAME);

????if (ret < 0) {

????????printk(KERN_ALERT "Failed to allocate device number: %dn", ret);

????????return ret;

}

???major=MAJOR(dev_num);

???minor=MINOR(dev_num);

printk(KERN_INFO "major number: %dn",major);

printk(KERN_INFO "minor number: %dn",minor);

?

my_cdev.owner = THIS_MODULE;

????????cdev_init(&my_cdev,&fops);

????????cdev_add(&my_cdev,dev_num,1);

?

???????// 創(chuàng)建設(shè)備類(lèi)

????my_class = class_create(THIS_MODULE, "my_class");

????if (IS_ERR(my_class)) {

????????pr_err("Failed to create classn");

????????return PTR_ERR(my_class);

}

??// 創(chuàng)建設(shè)備節(jié)點(diǎn)并關(guān)聯(lián)到設(shè)備類(lèi)

????my_device = device_create(my_class, NULL, MKDEV(major, minor), NULL, DEVICE_NAME);

????if (IS_ERR(my_device)) {

????????pr_err("Failed to create devicen");

????????class_destroy(my_class);

????????return PTR_ERR(my_device);

????}

???????????printk(KERN_INFO "Device registered successfully.n");

????return 0;

}

static void __exit mydevice_exit(void)

{

// 在這里執(zhí)行驅(qū)動(dòng)程序的清理操作

// 銷(xiāo)毀設(shè)備節(jié)點(diǎn)

?device_destroy(my_class, MKDEV(major, minor));

// 銷(xiāo)毀設(shè)備類(lèi)

?class_destroy(my_class);

// 刪除字符設(shè)備

????cdev_del(&my_cdev);

????// 注銷(xiāo)字符設(shè)備驅(qū)動(dòng)程序

????unregister_chrdev(0, DEVICE_NAME);

?

????printk(KERN_INFO "Device unregistered.n");

}

?

module_init(mydevice_init);

module_exit(mydevice_exit);

?

MODULE_LICENSE("GPL"); ?????// 指定模塊的許可證信息

MODULE_AUTHOR("Your Name"); // 指定模塊的作者信息

MODULE_DESCRIPTION("A simple character device driver"); // 指定模塊的描述信息

. /opt/fsl-imx-x11/4.1.15-2.0.0/environment-setup-cortexa7hf-neon-poky-linux-gnueabi

elf@ubuntu:~/work/test/03_內(nèi)核空間與用戶(hù)空間的數(shù)據(jù)拷貝/copy_form_user$ make

#include <stdio.h>

#include <stdlib.h>

#include <unistd.h>

#include <sys/ioctl.h>

#include <errno.h>

#include <fcntl.h>

#include <string.h>

?

#define DEV_NAME "/dev/copy_form_user"

#define BUFFER_SIZE 1024

?

int main(int argc, char *argv[])

{

int reg;

int fd = 0;

char *write_buffer="Hello,kernel!This is user_buffer!";

?

?fd = open (DEV_NAME, O_RDWR);

?if (fd < 0) {

?perror("Open "DEV_NAME" Failed!n");

?exit(1);

?}

?

if (write(fd, write_buffer, strlen(write_buffer)) < 0) {

?????????printf("Failed to write to device file: %sn", DEV_NAME);

?????????close(fd);

?????????exit(1);

?}

?

?printf("Wrote to device file: %sn", DEV_NAME);

?close(fd);

?return 0;

?}

. /opt/fsl-imx-x11/4.1.15-2.0.0/environment-setup-cortexa7hf-neon-poky-linux-gnueabi ?

elf@ubuntu:~/work/test/03_內(nèi)核空間與用戶(hù)空間的數(shù)據(jù)拷貝/copy_form_user_app$ $CC copy_form_user.c -o copy_form_user

root@ELF1:~# insmod copy_form_user.ko

major number: 248

minor number: 0

Device registered successfully.

root@ELF1:~# ./copy_form_user

This is device_open.

This is device_write.

Received from user: Hello,kernel!This is user_buffer!Wrote to device file: /dev/copy_f

orm_user

This is device_release.

root@ELF1:~# rmmod copy_form_user.ko

Device unregistered.