oxygen_read_eeprom
u16 oxygen_read_eeprom(struct oxygen *chip, unsigned int index);
subdevice = oxygen_read_eeprom(chip, 2);
if (subdevice == 0xffff && oxygen_read_eeprom(chip, 1) == 0xffff)
eeprom_id = oxygen_read_eeprom(chip, 0);