CPSW_INTPRESCALE_MASK
int_ctrl &= ~(CPSW_INTPRESCALE_MASK | CPSW_INTPACEEN);
addnl_dvdr = CPSW_INTPRESCALE_MASK / prescale;
int_ctrl &= (~CPSW_INTPRESCALE_MASK);
int_ctrl |= (prescale & CPSW_INTPRESCALE_MASK);