(a) As used in this Code section, the term "penal institution" means any place of confinement for persons accused of or convicted of violating a law of this state or an ordinance of a municipality or political subdivision of this state.
(b) No person legally confined to a penal institution shall commit an unlawful act of violence or any other act in a violent or tumultuous manner in a penal institution.
(c) Any person who violates this Code section shall be guilty of a felony and, upon conviction thereof, shall be punished by imprisonment of not less than one year nor more than 20 years.