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

#define DEVICE_NAME "my_char_device"
#define CLASS_NAME "my_char_class"

static int majorNumber;                  // 设备号
static struct class* myCharClass = NULL; // 设备类
// 打开设备
static int dev_open(struct inode *inodep, struct file *filep) {
    printk(KERN_INFO "my_char_device: Device opened\n");
    return 0;
}

// 读取设备
static ssize_t dev_read(struct file *filep, char *buffer, size_t len, loff_t *offset) {
    printk(KERN_INFO "my_char_device: Read from device\n");
    return 0; // 返回0表示没有读取任何数据
}

// 写入设备
static ssize_t dev_write(struct file *filep, const char *buffer, size_t len, loff_t *offset) {
    printk(KERN_INFO "my_char_device: Write to device\n");
    return len; // 返回写入的字节数
}

// 释放设备
static int dev_release(struct inode *inodep, struct file *filep) {
    printk(KERN_INFO "my_char_device: Device closed\n");
    return 0;
}

// 文件操作结构体
static struct file_operations fops = {
    .owner = THIS_MODULE,
    .open = dev_open,
    .read = dev_read,
    .write = dev_write,
    .release = dev_release,
};

// 模块初始化
static int __init my_char_init(void) {
    // 自动申请设备号
    majorNumber = register_chrdev(0, DEVICE_NAME, &fops);
    if (majorNumber < 0) {
        printk(KERN_ALERT "my_char_device failed to register a major number\n");
        return majorNumber;
    }
    printk(KERN_INFO "my_char_device: registered correctly with major number %d\n", majorNumber);

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

    // 创建设备
    device_create(myCharClass, NULL, MKDEV(majorNumber, 0), NULL, DEVICE_NAME);
    printk(KERN_INFO "my_char_device: device class created correctly\n");
    return 0;
}

// 模块退出
static void __exit my_char_exit(void) {
    device_destroy(myCharClass, MKDEV(majorNumber, 0)); // 删除设备
    class_unregister(myCharClass);                       // 取消设备类注册
    class_destroy(myCharClass);                          // 销毁设备类
    unregister_chrdev(majorNumber, DEVICE_NAME);        // 注销设备号
    printk(KERN_INFO "my_char_device: Goodbye from the LKM!\n");
}

module_init(my_char_init);
module_exit(my_char_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Your Name");
MODULE_DESCRIPTION("A simple Linux char driver");
MODULE_VERSION("0.1");
