NAL: You should go and speak to an attorney about this after the holidays. I am assuming you got the officers name, badge number, etc. I am also assuming the officer did not knock, or attempt to notify you of intent to enter or made any interaction with you at all. If the officer simply crawled under the partially open garage door without notification or permission from you, then yes it would be unlawful entry. More than likely, someone made a complaint about your smoking weed in the garage and the officer went in to check it out. Either way, talk to an attorney and make sure there isnt any weed left on the premises and maybe give smoking it a break for a little while.