(Tualatin, OR)  --  Police say a homeless man is accused of punching a TriMet bus driver who refused to give him a free ride.  Authorities say 24-year-old Song Sushumna Landis punched the driver yesterday morning after being refused the free ride.  Police say the driver had asked Landis to leave a Tualatin bus shelter where he had been sleeping.  Landis is charged with third-degree assault and interfering with public transportation.