2 /* gain-time-scale conversion helpers for IIO light sensors
22  * iio_gts_get_gain - Convert scale to total gain
24  * Internal helper for converting scale to total gain.
29  * @scale:	Linearized scale to compute the gain for.
31  * Return:	(floored) gain corresponding to the scale. -EINVAL if scale
58  * gain_get_scale_fraction - get the gain or time based on scale and known one
63  * @scale:	Linearized scale to compute the gain/time for.
64  * @known:	Either integration time or gain depending on which one is known
65  * @unknown:	Pointer to variable where the computed gain/time is stored
67  * Internal helper for computing unknown fraction of total gain.
68  * Compute either gain or time based on scale and either the gain or time
84 	/* We require total gain to be exact multiple of known * unknown */  in gain_get_scale_fraction()
127  * iio_gts_total_gain_to_scale - convert gain to scale
128  * @gts:	Gain time scale descriptor
129  * @total_gain:	the gain to be converted
133  * Convert the total gain value to scale. NOTE: This does not separate gain
134  * generated by HW-gain or integration time. It is up to caller to decide what
135  * part of the total gain is due to integration time and what due to HW-gain.
154  * @gts:	Gain time scale descriptor
274  * @gts:	Gain time scale descriptor
277  * originally given gain and time tables. When both time and gain tables are
315 			per_time_gains[i][j] = gts->hwgain_table[j].gain *  in iio_gts_build_avail_scale_table()
353  * @gts:	Gain time scale descriptor
416  * @gts:	Gain time scale descriptor
431  * @gts:	Gain time scale descriptor
435  * given gain and given time tables.
437  * When both time and gain tables are
471  * @gts:	Gain time scale descriptor
490  * @gts:	Gain time scale descriptor
494  * given gain and given time tables.
496  * When both time and gain tables are given this results:
533 	if (g->sel < 0 || g->gain <= 0)  in sanity_check_gain()
560 			int gain, mul, res;  in iio_gts_sanity_check()  local
562 			gain = gts->hwgain_table[g].gain;  in iio_gts_sanity_check()
565 			if (check_mul_overflow(gain, mul, &res))  in iio_gts_sanity_check()
596  * devm_iio_init_iio_gts - Initialize the gain-time-scale helper
602  * @num_gain:		number of gains in the gain table
612  * Initialize the gain-time-scale helper for use. Note, gains, times, selectors
614  * checking. The total gain (maximum gain * maximum time multiplier) must not
637  * @gts:	Gain time scale descriptor
660  * @gts:	Gain time scale descriptor
694  * @gts:	Gain time scale descriptor
716  * iio_gts_find_sel_by_gain - find selector corresponding to a HW-gain
717  * @gts:	Gain time scale descriptor
718  * @gain:	HW-gain for which matching selector is searched for
720  * Return:	a selector matching given HW-gain or -EINVAL if selector was
723 int iio_gts_find_sel_by_gain(struct iio_gts *gts, int gain)  in iio_gts_find_sel_by_gain()  argument
728 		if (gts->hwgain_table[i].gain == gain)  in iio_gts_find_sel_by_gain()
736  * iio_gts_find_gain_by_sel - find HW-gain corresponding to a selector
737  * @gts:	Gain time scale descriptor
738  * @sel:	selector for which matching HW-gain is searched for
740  * Return:	a HW-gain matching given selector or -EINVAL if HW-gain was not
749 			return gts->hwgain_table[i].gain;  in iio_gts_find_gain_by_sel()
756  * iio_gts_get_min_gain - find smallest valid HW-gain
757  * @gts:	Gain time scale descriptor
759  * Return:	The smallest HW-gain -EINVAL if no HW-gains were in the tables.
766 		int gain = gts->hwgain_table[i].gain;  in iio_gts_get_min_gain()  local
769 			min = gain;  in iio_gts_get_min_gain()
771 			min = min(min, gain);  in iio_gts_get_min_gain()
779  * iio_find_closest_gain_low - Find the closest lower matching gain
780  * @gts:	Gain time scale descriptor
781  * @gain:	HW-gain for which the closest match is searched
782  * @in_range:	indicate if the @gain was actually in the range of
785  * Search for closest supported gain that is lower than or equal to the
786  * gain given as a parameter. This is usable for drivers which do not require
787  * user to request exact matching gain but rather for rounding to a supported
788  * gain value which is equal or lower (setting lower gain is typical for
791  * Return:	The closest matching supported gain or -EINVAL if @gain
792  *		was smaller than the smallest supported gain.
794 int iio_find_closest_gain_low(struct iio_gts *gts, int gain, bool *in_range)  in iio_find_closest_gain_low()  argument
802 		if (gain == gts->hwgain_table[i].gain) {  in iio_find_closest_gain_low()
804 			return gain;  in iio_find_closest_gain_low()
807 		if (gain > gts->hwgain_table[i].gain) {  in iio_find_closest_gain_low()
809 				diff = gain - gts->hwgain_table[i].gain;  in iio_find_closest_gain_low()
812 				int tmp = gain - gts->hwgain_table[i].gain;  in iio_find_closest_gain_low()
821 			 * We found valid HW-gain which is greater than  in iio_find_closest_gain_low()
823 			 * will have found an in-range gain  in iio_find_closest_gain_low()
828 	/* The requested gain was smaller than anything we support */  in iio_find_closest_gain_low()
835 	return gts->hwgain_table[best].gain;  in iio_find_closest_gain_low()
852  * iio_gts_find_gain_for_scale_using_time - Find gain by time and scale
853  * @gts:	Gain time scale descriptor
854  * @time_sel:	Integration time selector corresponding to the time gain is
858  * @gain:	Pointer to value where gain is stored.
860  * In some cases the light sensors may want to find a gain setting which
862  * gain and time tables may use this helper to retrieve the gain.
864  * Return:	0 on success. -EINVAL if gain matching the parameters is not
869 						  int *gain)  in iio_gts_find_gain_for_scale_using_time()  argument
884 	ret = gain_get_scale_fraction(gts->max_scale, scale_linear, mul, gain);  in iio_gts_find_gain_for_scale_using_time()
888 	if (!iio_gts_valid_gain(gts, *gain))  in iio_gts_find_gain_for_scale_using_time()
895  * iio_gts_find_gain_sel_for_scale_using_time - Fetch gain selector.
896  * @gts:	Gain time scale descriptor
897  * @time_sel:	Integration time selector corresponding to the time gain is
901  * @gain_sel:	Pointer to value where gain selector is stored.
909 	int gain, ret;  in iio_gts_find_gain_sel_for_scale_using_time()  local
912 						     scale_nano, &gain);  in iio_gts_find_gain_sel_for_scale_using_time()
916 	ret = iio_gts_find_sel_by_gain(gts, gain);  in iio_gts_find_gain_sel_for_scale_using_time()
926 static int iio_gts_get_total_gain(struct iio_gts *gts, int gain, int time)  in iio_gts_get_total_gain()  argument
930 	if (!iio_gts_valid_gain(gts, gain))  in iio_gts_get_total_gain()
934 		return gain;  in iio_gts_get_total_gain()
940 	return gain * itime->mul;  in iio_gts_get_total_gain()
943 static int iio_gts_get_scale_linear(struct iio_gts *gts, int gain, int time,  in iio_gts_get_scale_linear()  argument
949 	total_gain = iio_gts_get_total_gain(gts, gain, time);  in iio_gts_get_scale_linear()
963  * iio_gts_get_scale - get scale based on integration time and HW-gain
964  * @gts:	Gain time scale descriptor
965  * @gain:	HW-gain for which the scale is computed
970  * Compute scale matching the integration time and HW-gain given as parameter.
974 int iio_gts_get_scale(struct iio_gts *gts, int gain, int time, int *scale_int,  in iio_gts_get_scale()  argument
980 	ret = iio_gts_get_scale_linear(gts, gain, time, &lin_scale);  in iio_gts_get_scale()
990  * @gts:		Gain time scale descriptor
991  * @old_gain:		Previously set gain
994  * @new_gain:		Pointer to value where new gain is to be written
997  * time (for a light sensor) by also updating the (HW)gain. This helper computes
998  * new gain value to maintain the scale with new integration time.
1000  * Return: 0 if an exactly matching supported new gain was found. When a
1002  * positive value. The negative value means that no gain could be computed.
1003  * Positive value will be the "best possible new gain there could be". There
1004  * can be two reasons why finding the "best possible" new gain is not deemed
1006  * gain required to maintain the scale would not be an integer. In this case,
1007  * the "best possible" new gain will be a floored optimal gain, which may or
1047  * @gts:		Gain time scale descriptor
1048  * @old_gain:		Previously set gain
1051  * @new_gain:		Pointer to value where new gain is to be written
1054  * time (for a light sensor) by also updating the (HW)gain. This helper computes
1055  * new gain value to maintain the scale with new integration time.
1057  * Return: 0 if an exactly matching supported new gain was found. When a
1059  * positive value. The negative value means that no gain could be computed.
1060  * Positive value will be the "best possible new gain there could be". There
1061  * can be two reasons why finding the "best possible" new gain is not deemed
1063  * gain required to maintain the scale would not be an integer. In this case,
1064  * the "best possible" new gain will be a floored optimal gain, which may or
1099 MODULE_DESCRIPTION("IIO light sensor gain-time-scale helpers");