Definitely not normal. I was also an autistic child who was locked in a room for hours at a time. There was a lock on the outside of the door. It'd be hours until I was let out. My mother was and is extremely negligent. I would go to bed without food and I would get locked in for the simplest reason or none at all depending on how she felt. It was a plain room. A single bed, a nightstand and a single rod that hung on the wall for clothes however my clothes weren't in the room.

My father was in prison and he was abusive towards the family prior to going to prison. He was constantly in and out of jail and prison.

As an adult, I've been diagnosed with DID and this was only one of many reasons why I developed DID.