mul_u64_u64_div_u64_roundup
wf->period_length_ns = mul_u64_u64_div_u64_roundup(((u64)wfhw->psc + 1) * (wfhw->arr + 1),
ccr_ns = mul_u64_u64_div_u64_roundup(((u64)wfhw->psc + 1) * wfhw->ccr, NSEC_PER_SEC, rate);
mul_u64_u64_div_u64_roundup(((u64)wfhw->psc + 1) * (wfhw->arr + 1 - wfhw->ccr),
result_up = mul_u64_u64_div_u64_roundup(a, b, d);