if (serio->private != NULL) return -EBUSY;
if (serio_get_drvdata(serio) != NULL) return -EBUSY;
static int hil_mlc_serio_open(struct serio *serio) {	struct hil_mlc_serio_map *map;	struct hil_mlc *mlc;	if (serio->private != NULL) return -EBUSY;	map = serio->port_data;	if (map == NULL) {		BUG();		return -ENODEV;	}	mlc = map->mlc;	if (mlc == NULL) {		BUG();		return -ENODEV;	}	return 0;}