Is it legal to lock your kids out of the house?

My parents are divorced I'm 17 and a week ago I came home from school (walking 2.5 miles in the hot Florida sun mind you) and my mother wasn't home and refused to let me inside when I called her. I usually get in and out using the garage door we hardly ever use the front door. The garage door has a code on it but my mother had changed it and refused to tell me what the new code was. That's how she refused to let me in. She said she'd be home soon. Anyway I called my dad and he told me I should call the cops because its not legal to refuse entrance to someone living in your house. So I did and when the cop finally showed up he pretty much said it was perfectly acceptable to do this. I didn't go into the whole walking from school and possible heat stoke thing cause I could tell he didn't care. So I went back to sitting on the porch and waiting. A little while later my neighbor brought me water which I was really thankful for. Anyway my mothers "soon" ended up being an hour and eighteen minutes, I know I'm weird to have it timed exactly but what else are you supposed to do when you're trapped outside? She still won't give me the code or a key and she actually gave our spare key away. I feel really degraded too cause her boyfriend (who does not live with us) is allowed full entrance to the house, but me, her own daughter gets purposely locked outside. It's worse that I don't even want to live with her but that's beside the point. So is it legal?