Facing the players game object (upward, downward, left, right) on Android phone using joystick

I am creating a 2d top down game and its going good. But i have a problem with my controller joystick. As of now, i have only a left and right movement which has an animation. But i need to have a upward and downward also to make the player game object more flexible.

             x_position = transform.position.x;
             y_position = transform.position.y;
             if (x_position < transform.position.x) {
                   facing = "left";
             } else if (x_position > transform.position.x){
                 facing = "right";
             }
                     x_position = transform.position.x;
                     y_position = transform.position.y;

If my game is only for pc, I can use Input.GetAxis() to do the logic. But this is for mobile and im having a hard time solving this problem. How can i fix this?