PLL2550XX_S_SHIFT
sdiv = (pll_con >> PLL2550XX_S_SHIFT) & PLL2550XX_S_MASK;
tmp &= ~(PLL2550XX_S_MASK << PLL2550XX_S_SHIFT);
tmp |= rate->sdiv << PLL2550XX_S_SHIFT;
(PLL2550XX_S_MASK << PLL2550XX_S_SHIFT));
(rate->sdiv << PLL2550XX_S_SHIFT);