Power up a 2nd core?

[WhiteHexagon]

I can see a PRCM register for CPU1_PWR_CLAMP that looks relevant for powering up a 2nd core.  But I cant find any info about this, and since it seems to be an 8 bit value I am very relucatant to hack it.  Is it documented anywhere please? or in general the whole 2nd core startup would be useful.  I can take a guess at some of the steps, but it would be nice to follow something official and not melt my chip

[WhiteHexagon]

I went with the following values, which I found as being used by the original allwinner code.  No idea if this is still the best way, but it seems to work     

const POWER_UP = [_]u8{0xFE, 0xF8, 0xE0, 0x80, 0x00};