RPM_PFC_CLASS_MASK
cfg = FIELD_SET(RPM_PFC_CLASS_MASK, 0, cfg);
pfc_en |= FIELD_GET(RPM_PFC_CLASS_MASK, class_en);
class_en = FIELD_SET(RPM_PFC_CLASS_MASK, pfc_en, class_en);
class_en = FIELD_SET(RPM_PFC_CLASS_MASK, 0, class_en);