PWM_ASPEED_DUTY_CYCLE_PERIOD
duty_cycle_period = FIELD_GET(PWM_ASPEED_DUTY_CYCLE_PERIOD, val);
val &= ~PWM_ASPEED_DUTY_CYCLE_PERIOD;
val |= FIELD_PREP(PWM_ASPEED_DUTY_CYCLE_PERIOD,
#define PWM_ASPEED_FIXED_PERIOD FIELD_MAX(PWM_ASPEED_DUTY_CYCLE_PERIOD)