Commit eb13959e authored by Matti Vaittinen's avatar Matti Vaittinen Committed by Jonathan Cameron
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bu27034: ROHM BU27034ANUC correct lux calculation 



The ROHM BU27034NUC was cancelled and BU27034ANUC is replacing this
sensor. The lux computation based on the data from a BU27034ANUC is
different from the computation for the data from an old BU27034NUC.

Fix the lux computation.

Signed-off-by: default avatarMatti Vaittinen <mazziesaccount@gmail.com>
Link: https://patch.msgid.link/b7bea76b54b28eb354dc523771a0e0a8b6f26095.1720176341.git.mazziesaccount@gmail.com


Signed-off-by: default avatarJonathan Cameron <Jonathan.Cameron@huawei.com>
parent bb105981

drivers/iio/light/rohm-bu27034.c

+31 −126
Original line number Diff line number Diff line
@@ -573,102 +573,21 @@ static int bu27034_set_scale(struct bu27034_data *data, int chan, 
}



/*

 * for (D1/D0 < 0.87):

 * lx = 0.004521097 * D1 - 0.002663996 * D0 +

 *	0.00012213 * D1 * D1 / D0

 * for (D1/D0 < 1.5):

 *    lx = (0.001193 * D0 + (-0.0000747) * D1) * ((D1/D0 – 1.5) * (0.25) + 1)

 *

 * =>	115.7400832 * ch1 / gain1 / mt -

 *	68.1982976 * ch0 / gain0 / mt +

 *	0.00012213 * 25600 * (ch1 / gain1 / mt) * 25600 *

 *	(ch1 /gain1 / mt) / (25600 * ch0 / gain0 / mt)

 *    => -0.000745625 * D0 + 0.0002515625 * D1 + -0.000018675 * D1 * D1 / D0

 *

 * A =	0.00012213 * 25600 * (ch1 /gain1 / mt) * 25600 *

 *	(ch1 /gain1 / mt) / (25600 * ch0 / gain0 / mt)

 * =>	0.00012213 * 25600 * (ch1 /gain1 / mt) *

 *	(ch1 /gain1 / mt) / (ch0 / gain0 / mt)

 * =>	0.00012213 * 25600 * (ch1 / gain1) * (ch1 /gain1 / mt) /

 *	(ch0 / gain0)

 * =>	0.00012213 * 25600 * (ch1 / gain1) * (ch1 /gain1 / mt) *

 *	gain0 / ch0

 * =>	3.126528 * ch1 * ch1 * gain0 / gain1 / gain1 / mt /ch0

 *

 * lx = (115.7400832 * ch1 / gain1 - 68.1982976 * ch0 / gain0) /

 *	mt + A

 * =>	(115.7400832 * ch1 / gain1 - 68.1982976 * ch0 / gain0) /

 *	mt + 3.126528 * ch1 * ch1 * gain0 / gain1 / gain1 / mt /

 *	ch0

 *

 * =>	(115.7400832 * ch1 / gain1 - 68.1982976 * ch0 / gain0 +

 *	  3.126528 * ch1 * ch1 * gain0 / gain1 / gain1 / ch0) /

 *    => (6.44 * ch1 / gain1 + 19.088 * ch0 / gain0 -

 *       0.47808 * ch1 * ch1 * gain0 / gain1 / gain1 / ch0) /

 *       mt

 *

 * For (0.87 <= D1/D0 < 1.00)

 * lx = (0.001331* D0 + 0.0000354 * D1) * ((D1/D0 – 0.87) * (0.385) + 1)

 * =>	(0.001331 * 256 * 100 * ch0 / gain0 / mt + 0.0000354 * 256 *

 *	100 * ch1 / gain1 / mt) * ((D1/D0 -  0.87) * (0.385) + 1)

 * =>	(34.0736 * ch0 / gain0 / mt + 0.90624 * ch1 / gain1 / mt) *

 *	((D1/D0 -  0.87) * (0.385) + 1)

 * =>	(34.0736 * ch0 / gain0 / mt + 0.90624 * ch1 / gain1 / mt) *

 *	(0.385 * D1/D0 - 0.66505)

 * =>	(34.0736 * ch0 / gain0 / mt + 0.90624 * ch1 / gain1 / mt) *

 *	(0.385 * 256 * 100 * ch1 / gain1 / mt / (256 * 100 * ch0 / gain0 / mt) - 0.66505)

 * =>	(34.0736 * ch0 / gain0 / mt + 0.90624 * ch1 / gain1 / mt) *

 *	(9856 * ch1 / gain1 / mt / (25600 * ch0 / gain0 / mt) + 0.66505)

 * =>	13.118336 * ch1 / (gain1 * mt)

 *	+ 22.66064768 * ch0 / (gain0 * mt)

 *	+ 8931.90144 * ch1 * ch1 * gain0 /

 *	  (25600 * ch0 * gain1 * gain1 * mt)

 *	+ 0.602694912 * ch1 / (gain1 * mt)

 *

 * =>	[0.3489024 * ch1 * ch1 * gain0 / (ch0 * gain1 * gain1)

 *	 + 22.66064768 * ch0 / gain0

 *	 + 13.721030912 * ch1 / gain1

 *	] / mt

 *

 * For (D1/D0 >= 1.00)

 *

 * lx	= (0.001331* D0 + 0.0000354 * D1) * ((D1/D0 – 2.0) * (-0.05) + 1)

 *	=> (0.001331* D0 + 0.0000354 * D1) * (-0.05D1/D0 + 1.1)

 *	=> (0.001331 * 256 * 100 * ch0 / gain0 / mt + 0.0000354 * 256 *

 *	   100 * ch1 / gain1 / mt) * (-0.05D1/D0 + 1.1)

 *	=> (34.0736 * ch0 / gain0 / mt + 0.90624 * ch1 / gain1 / mt) *

 *	   (-0.05 * 256 * 100 * ch1 / gain1 / mt / (256 * 100 * ch0 / gain0 / mt) + 1.1)

 *	=> (34.0736 * ch0 / gain0 / mt + 0.90624 * ch1 / gain1 / mt) *

 *	   (-1280 * ch1 / (gain1 * mt * 25600 * ch0 / gain0 / mt) + 1.1)

 *	=> (34.0736 * ch0 * -1280 * ch1 * gain0 * mt /( gain0 * mt * gain1 * mt * 25600 * ch0)

 *	    + 34.0736 * 1.1 * ch0 / (gain0 * mt)

 *	    + 0.90624 * ch1 * -1280 * ch1 *gain0 * mt / (gain1 * mt *gain1 * mt * 25600 * ch0)

 *	    + 1.1 * 0.90624 * ch1 / (gain1 * mt)

 *	=> -43614.208 * ch1 / (gain1 * mt * 25600)

 *	    + 37.48096  ch0 / (gain0 * mt)

 *	    - 1159.9872 * ch1 * ch1 * gain0 / (gain1 * gain1 * mt * 25600 * ch0)

 *	    + 0.996864 ch1 / (gain1 * mt)

 *	=> [

 *		- 0.045312 * ch1 * ch1 * gain0 / (gain1 * gain1 * ch0)

 *		- 0.706816 * ch1 / gain1

 *		+ 37.48096  ch0 /gain0

 *	   ] * mt

 *

 *

 * So, the first case (D1/D0 < 0.87) can be computed to a form:

 *

 * lx = (3.126528 * ch1 * ch1 * gain0 / (ch0 * gain1 * gain1) +

 *	 115.7400832 * ch1 / gain1 +

 *	-68.1982976 * ch0 / gain0

 *	 / mt

 *

 * Second case (0.87 <= D1/D0 < 1.00) goes to form:

 * Else

 *    lx = 0.001193 * D0 - 0.0000747 * D1

 *

 *	=> [0.3489024 * ch1 * ch1 * gain0 / (ch0 * gain1 * gain1) +

 *	    13.721030912 * ch1 / gain1 +

 *	    22.66064768 * ch0 / gain0

 *	   ] / mt

 *

 * Third case (D1/D0 >= 1.00) goes to form:

 *	=> [-0.045312 * ch1 * ch1 * gain0 / (ch0 * gain1 * gain1) +

 *	    -0.706816 * ch1 / gain1 +

 *	    37.48096  ch0 /(gain0

 *	   ] / mt

 *    => (1.91232 * ch1 / gain1 + 30.5408 * ch0 / gain0 +

 *        [0 * ch1 * ch1 * gain0 / gain1 / gain1 / ch0] ) /

 *        mt

 *

 * This can be unified to format:

 * lx = [
@@ -678,19 +597,14 @@ static int bu27034_set_scale(struct bu27034_data *data, int chan, 
 *	] / mt

 *

 * For case 1:

 * A = 3.126528,

 * B = 115.7400832

 * C = -68.1982976

 * A = -0.47808,

 * B = 6.44,

 * C = 19.088

 *

 * For case 2:

 * A = 0.3489024

 * B = 13.721030912

 * C = 22.66064768

 *

 * For case 3:

 * A = -0.045312

 * B = -0.706816

 * C = 37.48096

 * A = 0

 * B = 1.91232

 * C = 30.5408

 */



struct bu27034_lx_coeff {
@@ -795,21 +709,16 @@ static int bu27034_fixp_calc_lx(unsigned int ch0, unsigned int ch1, 
{

	static const struct bu27034_lx_coeff coeff[] = {

		{

			.A = 31265280,		/* 3.126528 */

			.B = 1157400832,	/*115.7400832 */

			.C = 681982976,		/* -68.1982976 */

			.is_neg = {false, false, true},

			.A = 4780800,		/* -0.47808 */

			.B = 64400000,		/* 6.44 */

			.C = 190880000,		/* 19.088 */

			.is_neg = { true, false, false },

		}, {

			.A = 3489024,		/* 0.3489024 */

			.B = 137210309,		/* 13.721030912 */

			.C = 226606476,		/* 22.66064768 */

			.A = 0,			/* 0 */

			.B = 19123200,		/* 1.91232 */

			.C = 305408000,		/* 30.5408 */

			/* All terms positive */

		}, {

			.A = 453120,		/* -0.045312 */

			.B = 7068160,		/* -0.706816 */

			.C = 374809600,		/* 37.48096 */

			.is_neg = {true, true, false},

		}

		},

	};

	const struct bu27034_lx_coeff *c = &coeff[coeff_idx];

	u64 res = 0, terms[3];
@@ -972,12 +881,10 @@ static int bu27034_get_single_result(struct bu27034_data *data, int chan, 
 * D1 = data1/ch1_gain/meas_time_ms * 25600

 *

 * Then:

 * if (D1/D0 < 0.87)

 *	lx = (0.001331 * D0 + 0.0000354 * D1) * ((D1 / D0 - 0.87) * 3.45 + 1)

 * else if (D1/D0 < 1)

 *	lx = (0.001331 * D0 + 0.0000354 * D1) * ((D1 / D0 - 0.87) * 0.385 + 1)

 * else

 *	lx = (0.001331 * D0 + 0.0000354 * D1) * ((D1 / D0 - 2) * -0.05 + 1)

 * If (D1/D0 < 1.5)

 *    lx = (0.001193 * D0 + (-0.0000747) * D1) * ((D1 / D0 – 1.5) * 0.25 + 1)

 * Else

 *    lx = (0.001193 * D0 + (-0.0000747) * D1)

 *

 * We use it here. Users who have for example some colored lens

 * need to modify the calculation but I hope this gives a starting point for
@@ -1028,12 +935,10 @@ static int bu27034_calc_mlux(struct bu27034_data *data, __le16 *res, int *val) 
		d1_d0_ratio_scaled /= ch0 * gain1;

	}



	if (d1_d0_ratio_scaled < 87)

	if (d1_d0_ratio_scaled < 150)

		ret = bu27034_fixp_calc_lx(ch0, ch1, gain0, gain1, meastime, 0);

	else if (d1_d0_ratio_scaled < 100)

		ret = bu27034_fixp_calc_lx(ch0, ch1, gain0, gain1, meastime, 1);

	else

		ret = bu27034_fixp_calc_lx(ch0, ch1, gain0, gain1, meastime, 2);

		ret = bu27034_fixp_calc_lx(ch0, ch1, gain0, gain1, meastime, 1);



	if (ret < 0)

		return ret;