linux设备驱动编程第三版

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

#define DEVICE_NAME "mychardev"
#define CLASS_NAME "mycharclass"

static int major_number;
static struct class* mycharclass;
static struct device* mychardevice;

static ssize_t device_read(struct file* filp, char* buffer, size_t length, loff_t* offset) {
    printk(KERN_INFO "Reading from device\n");
    return 0;
}

static ssize_t device_write(struct file* filp, const char* buffer, size_t length, loff_t* offset) {
    printk(KERN_INFO "Writing to device\n");
    return length;
}

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

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

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

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

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

module_init(mychardev_init);
module_exit(mychardev_exit);

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