Linux驱动模块加载：如何实现

5月 7th, 2025

在Linux中，驱动模块（也称为内核模块）是可以在运行时加载和卸载的代码片段，用于扩展内核的功能。以下是实现Linux驱动模块加载的基本步骤：

1. 编写驱动模块代码

首先，你需要编写驱动模块的源代码。以下是一个简单的示例，展示了一个基本的字符设备驱动模块：

#include <linux/module.h>   // 包含模块相关的宏和函数
#include <linux/kernel.h>   // 包含内核打印函数
#include <linux/init.h>     // 包含模块初始化和退出函数
#include <linux/fs.h>       // 包含文件系统相关函数
#include <linux/cdev.h>     // 包含字符设备相关函数

#define DEVICE_NAME "mydevice"
#define CLASS_NAME "myclass"

static int major_number;
static struct class* mydevice_class = NULL;
static struct cdev mydevice_cdev;

// 模块初始化函数
static int __init mydevice_init(void) {
    printk(KERN_INFO "%s: Initializing %s\n", DEVICE_NAME, DEVICE_NAME);

    // 注册字符设备
    major_number = register_chrdev(0, DEVICE_NAME, &mydevice_fops);
    if (major_number < 0) {
        printk(KERN_ALERT "%s: Failed to register a major number\n", DEVICE_NAME);
        return major_number;
    }

    // 创建设备类
    mydevice_class = class_create(THIS_MODULE, CLASS_NAME);
    if (IS_ERR(mydevice_class)) {
        unregister_chrdev(major_number, DEVICE_NAME);
        printk(KERN_ALERT "%s: Failed to register device class\n", DEVICE_NAME);
        return PTR_ERR(mydevice_class);
    }

    // 创建设备文件
    if (device_create(mydevice_class, NULL, MKDEV(major_number, 0), NULL, DEVICE_NAME) == NULL) {
        class_destroy(mydevice_class);
        unregister_chrdev(major_number, DEVICE_NAME);
        printk(KERN_ALERT "%s: Failed to create the device\n", DEVICE_NAME);
        return -1;
    }

    // 初始化字符设备
    cdev_init(&mydevice_cdev, &mydevice_fops);
    if (cdev_add(&mydevice_cdev, MKDEV(major_number, 0), 1) < 0) {
        device_destroy(mydevice_class, MKDEV(major_number, 0));
        class_destroy(mydevice_class);
        unregister_chrdev(major_number, DEVICE_NAME);
        printk(KERN_ALERT "%s: Failed to add cdev\n", DEVICE_NAME);
        return -1;
    }

    printk(KERN_INFO "%s: Device class created correctly\n", DEVICE_NAME);
    return 0;
}

// 模块退出函数
static void __exit mydevice_exit(void) {
    cdev_del(&mydevice_cdev);
    device_destroy(mydevice_class, MKDEV(major_number, 0));
    class_unregister(mydevice_class);
    class_destroy(mydevice_class);
    unregister_chrdev(major_number, DEVICE_NAME);
    printk(KERN_INFO "%s: Goodbye from %s!\n", DEVICE_NAME, DEVICE_NAME);
}

// 文件操作结构体
static struct file_operations mydevice_fops = {
    .owner = THIS_MODULE,
};

module_init(mydevice_init);
module_exit(mydevice_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Your Name");
MODULE_DESCRIPTION("A simple Linux character device driver");
MODULE_VERSION("0.1");

2. 编译驱动模块

使用Makefile来编译驱动模块。以下是一个简单的Makefile示例：

obj-m += mydevice.o

all:
	make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules

clean:
	make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean