mtd_div_by_ws
start_page = mtd_div_by_ws(start, mtd);
end_page = mtd_div_by_ws(start + ops->len - 1, mtd);
maxooblen = ((size_t)(mtd_div_by_ws(mtd->size, mtd) -
mtd_div_by_ws(offs, mtd)) *
info.pair = mtd_div_by_ws(ebofs, mtd);
int mod = mtd_div_by_ws(mtd->erasesize, mtd);
return mtd_div_by_ws(mtd_mod_by_eb(offs, mtd), mtd);