PWM_ASPEED_FIXED_PERIOD
divisor = (u64)NSEC_PER_SEC * (PWM_ASPEED_FIXED_PERIOD + 1) *
divisor = ((u64)NSEC_PER_SEC * (PWM_ASPEED_FIXED_PERIOD + 1)) << div_h;
PWM_ASPEED_FIXED_PERIOD);
if (duty_pt >= (PWM_ASPEED_FIXED_PERIOD + 1))