Basic PMBus querying from userspace

Credits for this code go to David Brownell who sent this to lm-sensors in 2008. Adopted by Jan Kundrát.

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vout Value

Hi,
thanks for your efforts @jktjkt .

After checking 4 different repos in order to get some pmbus readings at all, this here was the only one which worked for me.

I'm using it for a Dell D1600E-S0

which seems to be the same as DS1600SPE-3 - detailed documentation can be found here:
https://www.artesyn.com/power-supplies/product-docs/508/ds1600spe/trn_ac-dc_ds1600spe-3_trn_rele1413032695_techref.pdf

I had an issue with the vout value (screenshot attached).
And solved it by dividing the value by 512. I changed the code like this:

... (@line ~1710) of pmbus_peek.c

case 0:
  if (op->units == BITS) {
          printf("(BITMAP)");
  } else {
          double  d = value & 0x03ff;

Change:

         if (strstr(name, "vout")) {
                  d = value / 512.0;
          } else {

(Unchanged, just added the corresponding bracket "}" )

                  /* LINEAR encoding:
                  *  - 11 LSBs are signed mantissa
                  *  - 5 LSBs are signed exponent
                  */
                  if (value & 0x0400)
                          d = -d;
                  if (value & 0x8000)
                          d /= 1 <<
                                  (0x0f + 1 - (value >> 11) & 0x0f);
                  else if (value & 0x7100)
                          d *= 1 << (value >> 11);
          }
          printf("%g", d);
  }
  break;

Bests
Konrad