SV_ADCMULT
if (rate < 625000 / SV_ADCMULT)
rate = 625000 / SV_ADCMULT;
if (rate > 150000000 / SV_ADCMULT)
rate = 150000000 / SV_ADCMULT;
for (r = 0; rate < 75000000 / SV_ADCMULT; r += 0x20, rate <<= 1);
xr = ((SV_REFFREQUENCY / SV_ADCMULT) * xm) / xn;
snd_BUG_ON(SV_ADCMULT % 512);
params->rate_den = (SV_ADCMULT/512) * (m+2);