We have a 10 year old who from age of 2 woke up very early, and demanded to go downstairs and have breakfast. Like your son he expected the morning to follow a very clear routine and would not be deviated from it. In our case from 2-6 yrs it consisted of make a Brio train track, and have breakfast (other children still fast asleep at 6.30-7.30 which was his waking time), chat to Dad. As he has got older he still wakes very early, and we are now having the problem that he immediately comes downstairs and switches on the telly or computer (which I now hide, or take fuse out of)
He was diagnosed with ASD, and I am now discerning a sort of pattern, in that although he was perfectly well behaved, the ROUTINE was everything to him, Dad, downstairs, train track, breakfast, and he now has a new ROUTINE which is less holistic, and more screen-orientated, and we don't like it at all! And we don't like him waking early, when he clearly tired (and he is 10)
So the task is to change his expectation of what the routine consists of. I think by punishing him by withdrawing his toys, or ipad you aren't really teaching him what a new routine is. So you have to introduce the ROUTINE YOU WANT, just as another poster said, which consists of no screaming and some sort of compromise where he gets some attention first thing, but on your terms not his.
This could consist of you slowly moving the waking time forward, and teaching him that you will come in to his room to wake HIM, and he is to stay in his room with his toys till then.
I think one of the things we had to teach our son, who was eventually diagnosed with ASD at 8, that he could have a lovely little "haven" of time first thing, and it was for him to decide whether he wanted to sleep or read, or play, as long as he didn't disturb anyone else, or switch telly on. And this was reasonable, because we weren't going to leave him for long, and we would appear and have a lovely breakfast with him in due course, at a time mutually agreed. The nicer we were to him at breakfast, the more it re-inforced the idea that it was a good routine to wait. And I think he felt more relaxed knowing we were pleased with him, so that had a positive effect on his sleeping habits.
BUT, We are having to re-set his mornings atm so it is something that you have to be prepared to work at longterm (we have got lazy by allowing him to switch on telly, we thought he was no longer a problem in the mornings), but the most important thing is that you might actually making his behavioural issues WORSE if he is long term knackered, and he will be, if he gets up at 5am every morning. You can do it, and it is worth perservering with some sort of positive re-inforcement like the other poster said. Then tackle the time he gets up, after he has good associations with getting up itself. It is so sad to see them when they wake up, dog tired, not knowing what they want, and just so grumpy, and thinking they are hungry when in fact you know they just need to go back to sleep for a little longer...