SLEW_SYSDIV_SHIFT
div = (readl(sclk->slew_reg) >> SLEW_SYSDIV_SHIFT) & SLEW_SYSDIV;
v &= ~(SLEW_SYSDIV << SLEW_SYSDIV_SHIFT);
v |= (div - 1) << SLEW_SYSDIV_SHIFT;