Who got up/ did get up?

Subject-auxiliary inversion does not apply to questions headed by an interrogative pronoun representing the subject of the question, so there is no need for the dummy auxiliary do.

Whom did you get up? ... Here the interrogative pronoun Whom represents the object of get, so did is inserted to accomplish inversion with the subject, you.

Who got up? ... Here the interrogative pronoun Who represents the subject of get, so inversion is not required, and do is not inserted to accomplish it.