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
45  * gain_get_scale_fraction - get the gain or time based on scale and known one
50  * @scale:	Linearized scale to compute the gain/time for.
51  * @known:	Either integration time or gain depending on which one is known
52  * @unknown:	Pointer to variable where the computed gain/time is stored
54  * Internal helper for computing unknown fraction of total gain.
55  * Compute either gain or time based on scale and either the gain or time
71 	/* We require total gain to be exact multiple of known * unknown */  in gain_get_scale_fraction()
114  * iio_gts_total_gain_to_scale - convert gain to scale
115  * @gts:	Gain time scale descriptor
116  * @total_gain:	the gain to be converted
120  * Convert the total gain value to scale. NOTE: This does not separate gain
121  * generated by HW-gain or integration time. It is up to caller to decide what
122  * part of the total gain is due to integration time and what due to HW-gain.
141  * @gts:	Gain time scale descriptor
261  * @gts:	Gain time scale descriptor
264  * originally given gain and time tables. When both time and gain tables are
302 			per_time_gains[i][j] = gts->hwgain_table[j].gain *  in iio_gts_build_avail_scale_table()
342  * @gts:	Gain time scale descriptor
408  * @gts:	Gain time scale descriptor
423  * @gts:	Gain time scale descriptor
427  * given gain and given time tables.
429  * When both time and gain tables are
463  * @gts:	Gain time scale descriptor
482  * @gts:	Gain time scale descriptor
486  * given gain and given time tables.
488  * When both time and gain tables are given this results:
525 	if (g->sel < 0 || g->gain <= 0)  in sanity_check_gain()
552 			int gain, mul, res;  in iio_gts_sanity_check()  local
554 			gain = gts->hwgain_table[g].gain;  in iio_gts_sanity_check()
557 			if (check_mul_overflow(gain, mul, &res))  in iio_gts_sanity_check()
588  * devm_iio_init_iio_gts - Initialize the gain-time-scale helper
594  * @num_gain:		number of gains in the gain table
604  * Initialize the gain-time-scale helper for use. Note, gains, times, selectors
606  * checking. The total gain (maximum gain * maximum time multiplier) must not
629  * @gts:	Gain time scale descriptor
652  * @gts:	Gain time scale descriptor
686  * @gts:	Gain time scale descriptor
708  * iio_gts_find_sel_by_gain - find selector corresponding to a HW-gain
709  * @gts:	Gain time scale descriptor
710  * @gain:	HW-gain for which matching selector is searched for
712  * Return:	a selector matching given HW-gain or -EINVAL if selector was
715 int iio_gts_find_sel_by_gain(struct iio_gts *gts, int gain)  in iio_gts_find_sel_by_gain()  argument
720 		if (gts->hwgain_table[i].gain == gain)  in iio_gts_find_sel_by_gain()
728  * iio_gts_find_gain_by_sel - find HW-gain corresponding to a selector
729  * @gts:	Gain time scale descriptor
730  * @sel:	selector for which matching HW-gain is searched for
732  * Return:	a HW-gain matching given selector or -EINVAL if HW-gain was not
741 			return gts->hwgain_table[i].gain;  in iio_gts_find_gain_by_sel()
748  * iio_gts_get_min_gain - find smallest valid HW-gain
749  * @gts:	Gain time scale descriptor
751  * Return:	The smallest HW-gain -EINVAL if no HW-gains were in the tables.
758 		int gain = gts->hwgain_table[i].gain;  in iio_gts_get_min_gain()  local
761 			min = gain;  in iio_gts_get_min_gain()
763 			min = min(min, gain);  in iio_gts_get_min_gain()
771  * iio_find_closest_gain_low - Find the closest lower matching gain
772  * @gts:	Gain time scale descriptor
773  * @gain:	HW-gain for which the closest match is searched
774  * @in_range:	indicate if the @gain was actually in the range of
777  * Search for closest supported gain that is lower than or equal to the
778  * gain given as a parameter. This is usable for drivers which do not require
779  * user to request exact matching gain but rather for rounding to a supported
780  * gain value which is equal or lower (setting lower gain is typical for
783  * Return:	The closest matching supported gain or -EINVAL if @gain
784  *		was smaller than the smallest supported gain.
786 int iio_find_closest_gain_low(struct iio_gts *gts, int gain, bool *in_range)  in iio_find_closest_gain_low()  argument
794 		if (gain == gts->hwgain_table[i].gain) {  in iio_find_closest_gain_low()
796 			return gain;  in iio_find_closest_gain_low()
799 		if (gain > gts->hwgain_table[i].gain) {  in iio_find_closest_gain_low()
801 				diff = gain - gts->hwgain_table[i].gain;  in iio_find_closest_gain_low()
804 				int tmp = gain - gts->hwgain_table[i].gain;  in iio_find_closest_gain_low()
813 			 * We found valid HW-gain which is greater than  in iio_find_closest_gain_low()
815 			 * will have found an in-range gain  in iio_find_closest_gain_low()
820 	/* The requested gain was smaller than anything we support */  in iio_find_closest_gain_low()
827 	return gts->hwgain_table[best].gain;  in iio_find_closest_gain_low()
844  * iio_gts_find_gain_for_scale_using_time - Find gain by time and scale
845  * @gts:	Gain time scale descriptor
846  * @time_sel:	Integration time selector corresponding to the time gain is
850  * @gain:	Pointer to value where gain is stored.
852  * In some cases the light sensors may want to find a gain setting which
854  * gain and time tables may use this helper to retrieve the gain.
856  * Return:	0 on success. -EINVAL if gain matching the parameters is not
861 						  int *gain)  in iio_gts_find_gain_for_scale_using_time()  argument
876 	ret = gain_get_scale_fraction(gts->max_scale, scale_linear, mul, gain);  in iio_gts_find_gain_for_scale_using_time()
880 	if (!iio_gts_valid_gain(gts, *gain))  in iio_gts_find_gain_for_scale_using_time()
887  * iio_gts_find_gain_sel_for_scale_using_time - Fetch gain selector.
888  * @gts:	Gain time scale descriptor
889  * @time_sel:	Integration time selector corresponding to the time gain is
893  * @gain_sel:	Pointer to value where gain selector is stored.
901 	int gain, ret;  in iio_gts_find_gain_sel_for_scale_using_time()  local
904 						     scale_nano, &gain);  in iio_gts_find_gain_sel_for_scale_using_time()
908 	ret = iio_gts_find_sel_by_gain(gts, gain);  in iio_gts_find_gain_sel_for_scale_using_time()
918 static int iio_gts_get_total_gain(struct iio_gts *gts, int gain, int time)  in iio_gts_get_total_gain()  argument
922 	if (!iio_gts_valid_gain(gts, gain))  in iio_gts_get_total_gain()
926 		return gain;  in iio_gts_get_total_gain()
932 	return gain * itime->mul;  in iio_gts_get_total_gain()
935 static int iio_gts_get_scale_linear(struct iio_gts *gts, int gain, int time,  in iio_gts_get_scale_linear()  argument
941 	total_gain = iio_gts_get_total_gain(gts, gain, time);  in iio_gts_get_scale_linear()
955  * iio_gts_get_scale - get scale based on integration time and HW-gain
956  * @gts:	Gain time scale descriptor
957  * @gain:	HW-gain for which the scale is computed
962  * Compute scale matching the integration time and HW-gain given as parameter.
966 int iio_gts_get_scale(struct iio_gts *gts, int gain, int time, int *scale_int,  in iio_gts_get_scale()  argument
972 	ret = iio_gts_get_scale_linear(gts, gain, time, &lin_scale);  in iio_gts_get_scale()
982  * @gts:		Gain time scale descriptor
983  * @old_gain:		Previously set gain
986  * @new_gain:		Pointer to value where new gain is to be written
989  * time (for a light sensor) by also updating the (HW)gain. This helper computes
990  * new gain value to maintain the scale with new integration time.
992  * Return: 0 if an exactly matching supported new gain was found. When a
994  * positive value. The negative value means that no gain could be computed.
995  * Positive value will be the "best possible new gain there could be". There
996  * can be two reasons why finding the "best possible" new gain is not deemed
998  * gain required to maintain the scale would not be an integer. In this case,
999  * the "best possible" new gain will be a floored optimal gain, which may or
1039  * @gts:		Gain time scale descriptor
1040  * @old_gain:		Previously set gain
1043  * @new_gain:		Pointer to value where new gain is to be written
1046  * time (for a light sensor) by also updating the (HW)gain. This helper computes
1047  * new gain value to maintain the scale with new integration time.
1049  * Return: 0 if an exactly matching supported new gain was found. When a
1051  * positive value. The negative value means that no gain could be computed.
1052  * Positive value will be the "best possible new gain there could be". There
1053  * can be two reasons why finding the "best possible" new gain is not deemed
1055  * gain required to maintain the scale would not be an integer. In this case,
1056  * the "best possible" new gain will be a floored optimal gain, which may or
1091 MODULE_DESCRIPTION("IIO light sensor gain-time-scale helpers");