PLL_SYS_FBDIV_FRAC
fbdiv_frac = HREAD4(sc,base + PLL_SYS_FBDIV_FRAC - PLL_SYS_CS);
HWRITE4(sc, base + PLL_SYS_FBDIV_FRAC - PLL_SYS_CS, 0);
HWRITE4(sc, base + PLL_SYS_FBDIV_FRAC - PLL_SYS_CS, fbdiv_frac);