PWMCON_CLKDIV
if (cnt_period >= ((FIELD_MAX(PWMDWIDTH_PERIOD) + 1) << FIELD_MAX(PWMCON_CLKDIV))) {
clkdiv = FIELD_MAX(PWMCON_CLKDIV);
clkdiv = FIELD_GET(PWMCON_CLKDIV, wfhw->con);
clkdiv = FIELD_GET(PWMCON_CLKDIV, pwm_mediatek_readl(pc, pwm->hwpwm, PWMCON));