linux字符设备驱动模块

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

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

static int major_number;
static struct class* my_char_class = NULL;
static struct device* my_char_device = NULL;

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

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

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

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

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

static int __init my_char_device_init(void) {
    major_number = register_chrdev(0, DEVICE_NAME, &fops);
    if (major_number < 0) {
        printk(KERN_ALERT "Failed to register device
");
        return major_number;
    }
    printk(KERN_INFO "Registered correctly with major number %d
", major_number);

    my_char_class = class_create(THIS_MODULE, CLASS_NAME);
    if (IS_ERR(my_char_class)) {
        unregister_chrdev(major_number, DEVICE_NAME);
        printk(KERN_ALERT "Failed to register device class
");
        return PTR_ERR(my_char_class);
    }
    printk(KERN_INFO "Device class registered correctly
");

    my_char_device = device_create(my_char_class, NULL, MKDEV(major_number, 0), NULL, DEVICE_NAME);
    if (IS_ERR(my_char_device)) {
        class_destroy(my_char_class);
        unregister_chrdev(major_number, DEVICE_NAME);
        printk(KERN_ALERT "Failed to create the device
");
        return PTR_ERR(my_char_device);
    }
    printk(KERN_INFO "Device class created correctly
");
    return 0;
}

static void __exit my_char_device_exit(void) {
    device_destroy(my_char_class, MKDEV(major_number, 0));
    class_unregister(my_char_class);
    class_destroy(my_char_class);
    unregister_chrdev(major_number, DEVICE_NAME);
    printk(KERN_INFO "Goodbye, World!
");
}

module_init(my_char_device_init);
module_exit(my_char_device_exit);

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