how to stop an Interval function in my jquery jquery plugin

how to stop an Interval function in my jquery jquery plugin

i wrote a jquery plugin to make a div auto scroll,i used function
setInterval to make the div stop for a while and then keeps on scroll.
here is the code
(function($){
"use strict";
function scrolltotop(obj,height,speed){
var ch=parseInt($(obj).css("margin-top"))+29;
$(obj).parent().find(".moving").remove();
$(obj).after($(obj).clone().addClass("copy"));
$(obj).addClass("moving").removeClass("copy").animate({
"margin-top":-27
},speed);
loop=setInterval(function(){
ch+=27;
if(ch < height+27){
$(obj).animate({
"margin-top":-ch
},speed,function(){
loop;
})
}else{
clearInterval(loop);
scrolltotop($(obj).next(".copy"),height,speed);
}
},4000)
}
$.fn.extend({
autoscroll: function(options) {
var defaults = {
speed: 1000,
scroller : '#scroller',
scroller_container : '#scroller_container'
}
var options = $.extend(defaults, options);
var height=$(options.scroller).height();
var stop=stopscroll();
//console.log(height)
scrolltotop(options.scroller,height,options.speed);
},
});
}(jQuery));
$("#list2").autoscroll({scroller:"#list2",scroller_container:"#container_2"});
it works well,but idont know how to make the div stop scroll after i init
the plugin.