linux驱动 创建设备文件

c - 字符设备
b - 块设备

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

#define DEVICE_NAME "mydevice"
#define CLASS_NAME "mydevice_class"

static int major_number;
static struct class *myclass = NULL;
static struct device *mydevice = NULL;

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

static int mydevice_release(struct inode *inode, struct file *file) {
    printk(KERN_INFO "mydevice: Device closed.\n");
    return 0;
}

static ssize_t mydevice_read(struct file *file, char __user *buffer, size_t length, loff_t *offset) {
    printk(KERN_INFO "mydevice: Read operation.\n");
    return 0;
}

static ssize_t mydevice_write(struct file *file, const char __user *buffer, size_t length, loff_t *offset) {
    printk(KERN_INFO "mydevice: Write operation.\n");
    return length;
}

static struct file_operations fops = {
    .open = mydevice_open,
    .release = mydevice_release,
    .read = mydevice_read,
    .write = mydevice_write,
};

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

    printk(KERN_INFO "mydevice: registered correctly with major number %d\n", major_number);

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

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

    return 0;
}

static void __exit mydevice_exit(void) {
    device_destroy(myclass, MKDEV(major_number, 0));
    class_unregister(myclass);
    class_destroy(myclass);
    unregister_chrdev(major_number, DEVICE_NAME);
    printk(KERN_INFO "mydevice: Goodbye, World!\n");
}

module_init(mydevice_init);
module_exit(mydevice_exit);

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

mknod /dev/mydevice c <major_number> 0
chmod 666 /dev/mydevice