linux驱动分析

#include <linux/module.h>
#include <linux/fs.h>

// 设备号
static dev_t dev_num;
// 设备类
static struct class *cls;
// 设备文件
static struct device *dev;

// 打开设备文件
static int my_open(struct inode *inode, struct file *file) {
    printk(KERN_INFO "Device opened
");
    return 0;
}

// 关闭设备文件
static int my_release(struct inode *inode, struct file *file) {
    printk(KERN_INFO "Device closed
");
    return 0;
}

// 文件操作结构体
static struct file_operations fops = {
    .open = my_open,
    .release = my_release,
};

// 驱动入口函数
static int __init my_init(void) {
    // 分配设备号
    alloc_chrdev_region(&dev_num, 0, 1, "my_device");
    // 创建设备类
    cls = class_create(THIS_MODULE, "my_device_class");
    // 创建设备文件
    dev = device_create(cls, NULL, dev_num, NULL, "my_device");
    // 注册驱动
    cdev_init(&my_cdev, &fops);
    cdev_add(&my_cdev, dev_num, 1);
    printk(KERN_INFO "Driver loaded
");
    return 0;
}

// 驱动出口函数
static void __exit my_exit(void) {
    // 注销驱动
    cdev_del(&my_cdev);
    // 销毁设备文件
    device_destroy(cls, dev_num);
    // 销毁设备类
    class_destroy(cls);
    // 释放设备号
    unregister_chrdev_region(dev_num, 1);
    printk(KERN_INFO "Driver unloaded
");
}

module_init(my_init);
module_exit(my_exit);

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