linux字符驱动例子

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

#define DEVICE_NAME "char_device"
#define CLASS_NAME "char_class"

static int major_number;
static struct class *char_class;
static struct device *device;
static struct cdev char_cdev;

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

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

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

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

static struct file_operations fops = {
    .owner = THIS_MODULE,
    .open = char_open,
    .release = char_release,
    .read = char_read,
    .write = char_write,
};

static int __init char_init(void) {
    major_number = register_chrdev(0, DEVICE_NAME, &fops);
    if (major_number < 0) {
        printk(KERN_ALERT "char device registration failed\n");
        return major_number;
    }
    printk(KERN_INFO "char device registered with major number %d\n", major_number);

    char_class = class_create(THIS_MODULE, CLASS_NAME);
    if (IS_ERR(char_class)) {
        unregister_chrdev(major_number, DEVICE_NAME);
        printk(KERN_ALERT "class creation failed\n");
        return PTR_ERR(char_class);
    }
    printk(KERN_INFO "class created\n");

    device = device_create(char_class, NULL, MKDEV(major_number, 0), NULL, DEVICE_NAME);
    if (IS_ERR(device)) {
        class_destroy(char_class);
        unregister_chrdev(major_number, DEVICE_NAME);
        printk(KERN_ALERT "device creation failed\n");
        return PTR_ERR(device);
    }
    printk(KERN_INFO "device created\n");

    cdev_init(&char_cdev, &fops);
    char_cdev.owner = THIS_MODULE;
    cdev_add(&char_cdev, MKDEV(major_number, 0), 1);

    return 0;
}

static void __exit char_exit(void) {
    device_destroy(char_class, MKDEV(major_number, 0));
    class_unregister(char_class);
    class_destroy(char_class);
    unregister_chrdev(major_number, DEVICE_NAME);
    printk(KERN_INFO "char device unregistered\n");
}

module_init(char_init);
module_exit(char_exit);

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