REG_INV
sc->cache.inv[gp->grpnum] = nct_read_reg(sc, REG_INV, gp->grpnum);
case REG_INV: return ("inv");
KASSERT(reg == REG_IOR || reg == REG_INV,
nct_set_pin_reg(sc, REG_INV, pin_num, val);