PMBUS_REVISION
ret = i2c_smbus_read_byte_data(client, PMBUS_REVISION);
if (pmbus_check_byte_register(client, 0, PMBUS_REVISION)) {
entries[idx].reg = PMBUS_REVISION;
rc = i2c_smbus_read_byte_data(psu->client, PMBUS_REVISION);
ret = pmbus_read_byte_data(client, 0, PMBUS_REVISION);