What is "upelluri"

In Hurrian mythology, Upelluri was the "dreaming god". Kumarbi placed the stone giant Ullikummi on Upelluri's shoulders to grow up. In his slumber, Upelluri was unaware of his burden. He has been compared to Atlas from Greek mythology. The Hittite counterpart was Ubelluris, a mountain god who carried the western edge of the sky on his shoulders.