SMSC47M1_REG_FANDIV
i = smsc47m1_read_value(data, SMSC47M1_REG_FANDIV);
tmp = smsc47m1_read_value(data, SMSC47M1_REG_FANDIV)
smsc47m1_write_value(data, SMSC47M1_REG_FANDIV, tmp);