18  * 2) calculate an estimated absolute voc index (0 - 500 index points) for
20  *    For this purpose the value of the resistance for which the voc index
35  * floating point calculation of voc is done as integer
140 static int sgp40_calc_voc(struct sgp40_data *data, u16 resistance_raw, int *voc)  in sgp40_calc_voc()  argument
150 	/* voc = 500 / (1 + e^x) */  in sgp40_calc_voc()
152 	*voc = 500 * ((1 << (SGP40_CALC_POWER * 2)) / ((1<<SGP40_CALC_POWER) + exp));  in sgp40_calc_voc()
154 	dev_dbg(data->dev, "raw: %d res_calibbias: %d x: %d exp: %d voc: %d\n",  in sgp40_calc_voc()
155 				resistance_raw, data->res_calibbias, x, exp, *voc);  in sgp40_calc_voc()
215 	int ret, voc;  in sgp40_read_raw()  local
246 		ret = sgp40_calc_voc(data, resistance_raw, &voc);  in sgp40_read_raw()
250 		*val = voc / (1 << SGP40_CALC_POWER);  in sgp40_read_raw()
253 		 * voc <= (500 * 2^SGP40_CALC_POWER) = 8192000  in sgp40_read_raw()
256 		*val2 = ((voc % (1 << SGP40_CALC_POWER)) * 244) / (1 << (SGP40_CALC_POWER - 12));  in sgp40_read_raw()
257 		dev_dbg(data->dev, "voc: %d val: %d.%06d\n", voc, *val, *val2);  in sgp40_read_raw()
337 	data->res_calibbias = 30000;	/* resistance raw value for voc index of 250 */  in sgp40_probe()