linux 设备节点 驱动

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

#define DEVICE_NAME "my_char_dev"
#define CLASS_NAME "my_char_class"

static int major_num;
static struct class *my_class;
static struct device *my_device;

static int my_open(struct inode *inode, struct file *file) {
    printk(KERN_INFO "My char device opened\n");
    return 0;
}

static int my_release(struct inode *inode, struct file *file) {
    printk(KERN_INFO "My char device closed\n");
    return 0;
}

static ssize_t my_read(struct file *file, char __user *buffer, size_t count, loff_t *ppos) {
    printk(KERN_INFO "Reading from my char device\n");
    return 0;
}

static ssize_t my_write(struct file *file, const char __user *buffer, size_t count, loff_t *ppos) {
    printk(KERN_INFO "Writing to my char device\n");
    return count;
}

static struct file_operations fops = {
    .open = my_open,
    .release = my_release,
    .read = my_read,
    .write = my_write,
};

static int __init my_init(void) {
    major_num = register_chrdev(0, DEVICE_NAME, &fops);
    if (major_num < 0) {
        printk(KERN_ALERT "Failed to register a major number\n");
        return major_num;
    }

    my_class = class_create(THIS_MODULE, CLASS_NAME);
    if (IS_ERR(my_class)) {
        unregister_chrdev(major_num, DEVICE_NAME);
        printk(KERN_ALERT "Failed to register device class\n");
        return PTR_ERR(my_class);
    }

    my_device = device_create(my_class, NULL, MKDEV(major_num, 0), NULL, DEVICE_NAME);
    if (IS_ERR(my_device)) {
        class_destroy(my_class);
        unregister_chrdev(major_num, DEVICE_NAME);
        printk(KERN_ALERT "Failed to create the device\n");
        return PTR_ERR(my_device);
    }

    printk(KERN_INFO "My char device registered correctly with major number %d\n", major_num);
    return 0;
}

static void __exit my_exit(void) {
    device_destroy(my_class, MKDEV(major_num, 0));
    class_unregister(my_class);
    class_destroy(my_class);
    unregister_chrdev(major_num, DEVICE_NAME);
    printk(KERN_INFO "My char device unregistered\n");
}

module_init(my_init);
module_exit(my_exit);

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