[anarmus]

Решил вот так:

function scrollUp() {
	window.scrollBy(0,-20);
	document.addEventListener("wheel", function() {a = 0;}, false);
	if (( a == 0) || (window.pageYOffset == 0)) {return;}
	else {requestAnimationFrame(scrollUp);}
}
document.getElementById('scrollUp').addEventListener('click', function(e) {
	e.preventDefault();
	a=1;
	scrollUp();
}, false);