PLL_REF_CLK_FREQ_MHZ
return (pll_ratio * PLL_REF_CLK_FREQ_MHZ * 2) / 3;
return (pll_ratio * PLL_REF_CLK_FREQ_MHZ) / 2;
return clamp_t(u32, freq_mhz / (PLL_REF_CLK_FREQ_MHZ / 2), 0, U8_MAX);