AW_PWM_MAX_FREQ
if (period_freq > AW_PWM_MAX_FREQ)
clk_rate = AW_PWM_MAX_FREQ;
div = AW_PWM_MAX_FREQ / period_freq;
div = AW_PWM_MAX_FREQ / aw_pwm_clk_prescaler[i] / period_freq;
clk_rate = AW_PWM_MAX_FREQ / aw_pwm_clk_prescaler[i];