linux字符设备的创建

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

#define DEVICE_NAME "mychardev"
#define MAJOR_NUM 240

static int device_open(struct inode *inode, struct file *file) {
    printk(KERN_INFO "Device opened\n");
    return 0;
}

static ssize_t device_read(struct file *file, char __user *buffer, size_t length, loff_t *offset) {
    printk(KERN_INFO "Device read\n");
    return 0;
}

static ssize_t device_write(struct file *file, const char __user *buffer, size_t length, loff_t *offset) {
    printk(KERN_INFO "Device write\n");
    return length;
}

static struct file_operations fops = {
    .open = device_open,
    .read = device_read,
    .write = device_write,
};

static int __init mychardev_init(void) {
    int ret;
    ret = register_chrdev(MAJOR_NUM, DEVICE_NAME, &fops);
    if (ret < 0) {
        printk(KERN_ALERT "Failed to register device, error code: %d\n", ret);
        return ret;
    }
    printk(KERN_INFO "Device registered with major number %d\n", MAJOR_NUM);
    return 0;
}

static void __exit mychardev_exit(void) {
    unregister_chrdev(MAJOR_NUM, DEVICE_NAME);
    printk(KERN_INFO "Device unregistered\n");
}

module_init(mychardev_init);
module_exit(mychardev_exit);

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

sudo mknod /dev/mychardev c 240 0
sudo chmod 666 /dev/mychardev

KERNEL=="mychardev", NAME="mychardev", MODE="0666"

sudo udevadm control --reload-rules && sudo udevadm trigger