ltr390_register_read
ret = ltr390_register_read(data, LTR390_UVS_DATA);
ret = ltr390_register_read(data, LTR390_ALS_DATA);
ret = ltr390_register_read(data, LTR390_THRESH_UP);
ret = ltr390_register_read(data, LTR390_THRESH_LOW);