Function: windmove-up

Select the window above the current one.
With no prefix argument, or with prefix argument equal to zero, "up"
is relative to the position of point in the window; otherwise it is
relative to the left edge (for positive ARG) or the right edge (for
negative ARG) of the current window.
If no window is at the desired location, an error is signaled. (fn &optional ARG)