linux字符驱动 设备id

#include <linux/fs.h>
#include <linux/module.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 __init my_char_init(void) {
    // 分配主设备号
    major_number = alloc_chrdev_region(&major_number, 0, 1, DEVICE_NAME);
    if (major_number < 0) {
        printk(KERN_ALERT "Failed to allocate major number
");
        return major_number;
    }

    // 创建设备类
    my_char_class = class_create(THIS_MODULE, CLASS_NAME);
    if (IS_ERR(my_char_class)) {
        unregister_chrdev_region(major_number, 1);
        printk(KERN_ALERT "Failed to create device class
");
        return PTR_ERR(my_char_class);
    }

    // 创建设备节点
    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_region(major_number, 1);
        printk(KERN_ALERT "Failed to create device node
");
        return PTR_ERR(my_char_device);
    }

    printk(KERN_INFO "Character device %s initialized with major number %d
", DEVICE_NAME, major_number);
    return 0;
}

static void __exit my_char_exit(void) {
    device_destroy(my_char_class, MKDEV(major_number, 0));
    class_unregister(my_char_class);
    class_destroy(my_char_class);
    unregister_chrdev_region(major_number, 1);
    printk(KERN_INFO "Character device %s removed
", DEVICE_NAME);
}

module_init(my_char_init);
module_exit(my_char_exit);

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