path: root/drivers/iio/adc/pac1921.c

// SPDX-License-Identifier: GPL-2.0+
/*
 * IIO driver for PAC1921 High-Side Power/Current Monitor
 *
 * Copyright (C) 2024 Matteo Martelli <matteomartelli3@gmail.com>
 */

#include <linux/unaligned.h>
#include <linux/bitfield.h>
#include <linux/i2c.h>
#include <linux/iio/events.h>
#include <linux/iio/iio.h>
#include <linux/iio/trigger_consumer.h>
#include <linux/iio/triggered_buffer.h>
#include <linux/regmap.h>
#include <linux/units.h>

/* pac1921 registers */
#define PAC1921_REG_GAIN_CFG		0x00
#define PAC1921_REG_INT_CFG		0x01
#define PAC1921_REG_CONTROL		0x02
#define PAC1921_REG_VBUS		0x10
#define PAC1921_REG_VSENSE		0x12
#define PAC1921_REG_OVERFLOW_STS	0x1C
#define PAC1921_REG_VPOWER		0x1D

/* pac1921 gain configuration bits */
#define PAC1921_GAIN_DI_GAIN_MASK	GENMASK(5, 3)
#define PAC1921_GAIN_DV_GAIN_MASK	GENMASK(2, 0)

/* pac1921 integration configuration bits */
#define PAC1921_INT_CFG_SMPL_MASK	GENMASK(7, 4)
#define PAC1921_INT_CFG_VSFEN		BIT(3)
#define PAC1921_INT_CFG_VBFEN		BIT(2)
#define PAC1921_INT_CFG_RIOV		BIT(1)
#define PAC1921_INT_CFG_INTEN		BIT(0)

/* pac1921 control bits */
#define PAC1921_CONTROL_MXSL_MASK	GENMASK(7, 6)
enum pac1921_mxsl {
	PAC1921_MXSL_VPOWER_PIN = 0,
	PAC1921_MXSL_VSENSE_FREE_RUN = 1,
	PAC1921_MXSL_VBUS_FREE_RUN = 2,
	PAC1921_MXSL_VPOWER_FREE_RUN = 3,
};
#define PAC1921_CONTROL_SLEEP		BIT(2)

/* pac1921 result registers mask and resolution */
#define PAC1921_RES_MASK		GENMASK(15, 6)
#define PAC1921_RES_RESOLUTION		1023

/* pac1921 overflow status bits */
#define PAC1921_OVERFLOW_VSOV		BIT(2)
#define PAC1921_OVERFLOW_VBOV		BIT(1)
#define PAC1921_OVERFLOW_VPOV		BIT(0)

/* pac1921 constants */
#define PAC1921_MAX_VSENSE_MV		100
#define PAC1921_MAX_VBUS_V		32
/* Time to first communication after power up (tINT_T) */
#define PAC1921_POWERUP_TIME_MS		20
/* Time from Sleep State to Start of Integration Period (tSLEEP_TO_INT) */
#define PAC1921_SLEEP_TO_INT_TIME_US	86

/* pac1921 defaults */
#define PAC1921_DEFAULT_DV_GAIN		0 /* 2^(value): 1x gain (HW default) */
#define PAC1921_DEFAULT_DI_GAIN		0 /* 2^(value): 1x gain (HW default) */
#define PAC1921_DEFAULT_NUM_SAMPLES	0 /* 2^(value): 1 sample (HW default) */

/*
 * Pre-computed scale factors for BUS voltage
 * format: IIO_VAL_INT_PLUS_NANO
 * unit: mV
 *
 * Vbus scale (mV) = max_vbus (mV) / dv_gain / resolution
 */
static const int pac1921_vbus_scales[][2] = {
	{ 31, 280547409 },	/* dv_gain x1 */
	{ 15, 640273704 },	/* dv_gain x2 */
	{ 7, 820136852 },	/* dv_gain x4 */
	{ 3, 910068426 },	/* dv_gain x8 */
	{ 1, 955034213 },	/* dv_gain x16 */
	{ 0, 977517106 },	/* dv_gain x32 */
};

/*
 * Pre-computed scales for SENSE voltage
 * format: IIO_VAL_INT_PLUS_NANO
 * unit: mV
 *
 * Vsense scale (mV) = max_vsense (mV) / di_gain / resolution
 */
static const int pac1921_vsense_scales[][2] = {
	{ 0, 97751710 },	/* di_gain x1 */
	{ 0, 48875855 },	/* di_gain x2 */
	{ 0, 24437927 },	/* di_gain x4 */
	{ 0, 12218963 },	/* di_gain x8 */
	{ 0, 6109481 },		/* di_gain x16 */
	{ 0, 3054740 },		/* di_gain x32 */
	{ 0, 1527370 },		/* di_gain x64 */
	{ 0, 763685 },		/* di_gain x128 */
};

/*
 * Numbers of samples used to integrate measurements at the end of an
 * integration period.
 *
 * Changing the number of samples affects the integration period: higher the
 * number of samples, longer the integration period.
 *
 * These correspond to the oversampling ratios available exposed to userspace.
 */
static const int pac1921_int_num_samples[] = {
	1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048
};

/*
 * The integration period depends on the configuration of number of integration
 * samples, measurement resolution and post filters. The following array
 * contains integration periods, in microsecs unit, based on table 4-5 from
 * datasheet considering power integration mode, 14-Bit resolution and post
 * filters on. Each index corresponds to a specific number of samples from 1
 * to 2048.
 */
static const unsigned int pac1921_int_periods_usecs[] = {
	2720,		/* 1 sample */
	4050,		/* 2 samples */
	6790,		/* 4 samples */
	12200,		/* 8 samples */
	23000,		/* 16 samples */
	46000,		/* 32 samples */
	92000,		/* 64 samples */
	184000,		/* 128 samples */
	368000,		/* 256 samples */
	736000,		/* 512 samples */
	1471000,	/* 1024 samples */
	2941000		/* 2048 samples */
};

/* pac1921 regmap configuration */
static const struct regmap_range pac1921_regmap_wr_ranges[] = {
	regmap_reg_range(PAC1921_REG_GAIN_CFG, PAC1921_REG_CONTROL),
};

static const struct regmap_access_table pac1921_regmap_wr_table = {
	.yes_ranges = pac1921_regmap_wr_ranges,
	.n_yes_ranges = ARRAY_SIZE(pac1921_regmap_wr_ranges),
};

static const struct regmap_range pac1921_regmap_rd_ranges[] = {
	regmap_reg_range(PAC1921_REG_GAIN_CFG, PAC1921_REG_CONTROL),
	regmap_reg_range(PAC1921_REG_VBUS, PAC1921_REG_VPOWER + 1),