drivers/iio/adc/qcom-vadc-common.c

// SPDX-License-Identifier: GPL-2.0
#include <linux/bug.h>
#include <linux/kernel.h>
#include <linux/bitops.h>
#include <linux/math64.h>
#include <linux/log2.h>
#include <linux/err.h>
#include <linux/module.h>

#include "qcom-vadc-common.h"

/* Voltage to temperature */
static const struct vadc_map_pt adcmap_100k_104ef_104fb[] = {
	{1758,	-40},
	{1742,	-35},
	{1719,	-30},
	{1691,	-25},
	{1654,	-20},
	{1608,	-15},
	{1551,	-10},
	{1483,	-5},
	{1404,	0},
	{1315,	5},
	{1218,	10},
	{1114,	15},
	{1007,	20},
	{900,	25},
	{795,	30},
	{696,	35},
	{605,	40},
	{522,	45},
	{448,	50},
	{383,	55},
	{327,	60},
	{278,	65},
	{237,	70},
	{202,	75},
	{172,	80},
	{146,	85},
	{125,	90},
	{107,	95},
	{92,	100},
	{79,	105},
	{68,	110},
	{59,	115},
	{51,	120},
	{44,	125}
};

static int qcom_vadc_map_voltage_temp(const struct vadc_map_pt *pts,
				      u32 tablesize, s32 input, s64 *output)
{
	bool descending = 1;
	u32 i = 0;

	if (!pts)
		return -EINVAL;

	/* Check if table is descending or ascending */
	if (tablesize > 1) {
		if (pts[0].x < pts[1].x)
			descending = 0;
	}

	while (i < tablesize) {
		if ((descending) && (pts[i].x < input)) {
			/* table entry is less than measured*/
			 /* value and table is descending, stop */
			break;
		} else if ((!descending) &&
				(pts[i].x > input)) {
			/* table entry is greater than measured*/
			/*value and table is ascending, stop */
			break;
		}
		i++;
	}

	if (i == 0) {
		*output = pts[0].y;
	} else if (i == tablesize) {
		*output = pts[tablesize - 1].y;
	} else {
		/* result is between search_index and search_index-1 */
		/* interpolate linearly */
		*output = (((s32)((pts[i].y - pts[i - 1].y) *
			(input - pts[i - 1].x)) /
			(pts[i].x - pts[i - 1].x)) +
			pts[i - 1].y);
	}

	return 0;
}

static void qcom_vadc_scale_calib(const struct vadc_linear_graph *calib_graph,
				  u16 adc_code,
				  bool absolute,
				  s64 *scale_voltage)
{
	*scale_voltage = (adc_code - calib_graph->gnd);
	*scale_voltage *= calib_graph->dx;
	*scale_voltage = div64_s64(*scale_voltage, calib_graph->dy);
	if (absolute)
		*scale_voltage += calib_graph->dx;

	if (*scale_voltage < 0)
		*scale_voltage = 0;
}

static int qcom_vadc_scale_volt(const struct vadc_linear_graph *calib_graph,
				const struct vadc_prescale_ratio *prescale,
				bool absolute, u16 adc_code,
				int *result_uv)
{
	s64 voltage = 0, result = 0;

	qcom_vadc_scale_calib(calib_graph, adc_code, absolute, &voltage);

	voltage = voltage * prescale->den;
	result = div64_s64(voltage, prescale->num);
	*result_uv = result;

	return 0;
}

static int qcom_vadc_scale_therm(const struct vadc_linear_graph *calib_graph,
				 const struct vadc_prescale_ratio *prescale,
				 bool absolute, u16 adc_code,
				 int *result_mdec)
{
	s64 voltage = 0, result = 0;
	int ret;

	qcom_vadc_scale_calib(calib_graph, adc_code, absolute, &voltage);

	if (absolute)
		voltage = div64_s64(voltage, 1000);

	ret = qcom_vadc_map_voltage_temp(adcmap_100k_104ef_104fb,
					 ARRAY_SIZE(adcmap_100k_104ef_104fb),
					 voltage, &result);
	if (ret)
		return ret;

	result *= 1000;
	*result_mdec = result;

	return 0;
}

static int qcom_vadc_scale_die_temp(const struct vadc_linear_graph *calib_graph,
				    const struct vadc_prescale_ratio *prescale,
				    bool absolute,
				    u16 adc_code, int *result_mdec)
{
	s64 voltage = 0;
	u64 temp; /* Temporary variable for do_div */

	qcom_vadc_scale_calib(calib_graph, adc_code, absolute, &voltage);

	if (voltage > 0) {
		temp = voltage * prescale->den;
		do_div(temp, prescale->num * 2);
		voltage = temp;
	} else {
		voltage = 0;
	}

	voltage -= KELVINMIL_CELSIUSMIL;
	*result_mdec = voltage;

	return 0;
}

static int qcom_vadc_scale_chg_temp(const struct vadc_linear_graph *calib_graph,
				    const struct vadc_prescale_ratio *prescale,
				    bool absolute,
				    u16 adc_code, int *result_mdec)
{
	s64 voltage = 0, result = 0;

	qcom_vadc_scale_calib(calib_graph, adc_code, absolute, &voltage);

	voltage = voltage * prescale->den;
	voltage = div64_s64(voltage, prescale->num);
	voltage = ((PMI_CHG_SCALE_1) * (voltage * 2));
	voltage = (voltage + PMI_CHG_SCALE_2);
	result =  div64_s64(voltage, 1000000);
	*result_mdec = result;

	return 0;
}

int qcom_vadc_scale(enum vadc_scale_fn_type scaletype,
		    const struct vadc_linear_graph *calib_graph,
		    const struct vadc_prescale_ratio *prescale,
		    bool absolute,
		    u16 adc_code, int *result)
{
	switch (scaletype) {
	case SCALE_DEFAULT:
		return qcom_vadc_scale_volt(calib_graph, prescale,
					    absolute, adc_code,
					    result);
	case SCALE_THERM_100K_PULLUP:
	case SCALE_XOTHERM:
		return qcom_vadc_scale_therm(calib_graph, prescale,
					     absolute, adc_code,
					     result);
	case SCALE_PMIC_THERM:
		return qcom_vadc_scale_die_temp(calib_graph, prescale,
						absolute, adc_code,
						result);
	case SCALE_PMI_CHG_TEMP:
		return qcom_vadc_scale_chg_temp(calib_graph, prescale,
						absolute, adc_code,
						result);
	default:
		return -EINVAL;
	}
}
EXPORT_SYMBOL(qcom_vadc_scale);

int qcom_vadc_decimation_from_dt(u32 value)
{
	if (!is_power_of_2(value) || value < VADC_DECIMATION_MIN ||
	    value > VADC_DECIMATION_MAX)
		return -EINVAL;

	return __ffs64(value / VADC_DECIMATION_MIN);
}
EXPORT_SYMBOL(qcom_vadc_decimation_from_dt);

MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("Qualcomm ADC common functionality");