linux 驱动读写文件

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

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

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

static ssize_t device_read(struct file *file, char __user *buffer, size_t length, loff_t *offset) {
    char data[] = "Hello, World!";
    if (*offset >= sizeof(data))
        return 0;
    if (copy_to_user(buffer, data + *offset, sizeof(data) - *offset))
        return -EFAULT;
    *offset += sizeof(data) - *offset;
    return sizeof(data) - *offset;
}

static ssize_t device_write(struct file *file, const char __user *buffer, size_t length, loff_t *offset) {
    char data[length + 1];
    if (copy_from_user(data, buffer, length))
        return -EFAULT;
    data[length] = '\0';
    printk(KERN_INFO "Received data: %s\n", data);
    return length;
}

static const struct file_operations fops = {
    .owner = THIS_MODULE,
    .open = device_open,
    .release = device_release,
    .read = device_read,
    .write = device_write,
};

static int __init hello_init(void) {
    major_number = register_chrdev(0, "hello", &fops);
    if (major_number < 0) {
        printk(KERN_ALERT "Registering char device failed with %d\n", major_number);
        return major_number;
    }
    printk(KERN_INFO "Registered correctly with major number %d\n", major_number);
    return 0;
}

static void __exit hello_exit(void) {
    unregister_chrdev(major_number, "hello");
    printk(KERN_INFO "Device unregistered\n");
}

module_init(hello_init);
module_exit(hello_exit);

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