struct mcp251x {
    struct cdev cdev; 
    struct device sdev;
    struct class *cclass;
    int dev; /* device number */
}
static struct mcp251x *mcp251x_dev;
static int mcp251x_count=2；
static int __init mcp251x_init(void)
{
    mcp251x_dev = kmalloc(sizeof(struct mcp251x)*mcp251x_count,GFP_KERNEL);
    for (i=0; i<mcp251x_count; i++) {
        chip = &mcp251x_dev[i];
        alloc_chrdev_region(&chip->dev,/*base minor*/ 0, 1, DRIVER_NAME);//这里是不是重复申请了设备号，应该就一个主设备号啊
        chip->cclass = class_create(THIS_MODULE, DRIVER_NAME);
        cdev_init(&chip->cdev, &mcp251x_fops);
        chip->cdev.owner = THIS_MODULE;
        chip->cdev.ops = &mcp251x_fops;
        ret = cdev_add (&chip->cdev, chip->dev, 1);
        /* Fail gracefully if need be */
        if (ret)
            printk (KERN_NOTICE "Error %d adding can_lpc2xxx\n", ret);
        if (device_create(chip->cclass, NULL, 
            MKDEV(MAJOR(chip->dev), i), chip, DRIVER_NAME) == NULL) {
            printk("err----%s %d \n",__FILE__,__LINE__);
        }

    }

}