path: root/drivers/hwmon/ina238.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Driver for Texas Instruments INA238 power monitor chip
 * Datasheet: https://www.ti.com/product/ina238
 *
 * Copyright (C) 2021 Nathan Rossi <nathan.rossi@digi.com>
 */

#include <linux/bitops.h>
#include <linux/err.h>
#include <linux/hwmon.h>
#include <linux/i2c.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/regmap.h>

/* INA238 register definitions */
#define INA238_CONFIG			0x0
#define INA238_ADC_CONFIG		0x1
#define INA238_SHUNT_CALIBRATION	0x2
#define SQ52206_SHUNT_TEMPCO		0x3
#define INA238_SHUNT_VOLTAGE		0x4
#define INA238_BUS_VOLTAGE		0x5
#define INA238_DIE_TEMP			0x6
#define INA238_CURRENT			0x7
#define INA238_POWER			0x8
#define SQ52206_ENERGY			0x9
#define SQ52206_CHARGE			0xa
#define INA238_DIAG_ALERT		0xb
#define INA238_SHUNT_OVER_VOLTAGE	0xc
#define INA238_SHUNT_UNDER_VOLTAGE	0xd
#define INA238_BUS_OVER_VOLTAGE		0xe
#define INA238_BUS_UNDER_VOLTAGE	0xf
#define INA238_TEMP_LIMIT		0x10
#define INA238_POWER_LIMIT		0x11
#define SQ52206_POWER_PEAK		0x20
#define INA238_DEVICE_ID		0x3f /* not available on INA237 */

#define INA238_CONFIG_ADCRANGE		BIT(4)
#define SQ52206_CONFIG_ADCRANGE_HIGH	BIT(4)
#define SQ52206_CONFIG_ADCRANGE_LOW	BIT(3)

#define INA238_DIAG_ALERT_TMPOL		BIT(7)
#define INA238_DIAG_ALERT_SHNTOL	BIT(6)
#define INA238_DIAG_ALERT_SHNTUL	BIT(5)
#define INA238_DIAG_ALERT_BUSOL		BIT(4)
#define INA238_DIAG_ALERT_BUSUL		BIT(3)
#define INA238_DIAG_ALERT_POL		BIT(2)

#define INA238_REGISTERS		0x20

#define INA238_RSHUNT_DEFAULT		2500	/* uOhm */

/* Default configuration of device on reset. */
#define INA238_CONFIG_DEFAULT		0
#define SQ52206_CONFIG_DEFAULT		0x0005
/* 16 sample averaging, 1052us conversion time, continuous mode */
#define INA238_ADC_CONFIG_DEFAULT	0xfb6a
/* Configure alerts to be based on averaged value (SLOWALERT) */
#define INA238_DIAG_ALERT_DEFAULT	0x2000
#define INA238_DIAG_ALERT_APOL		BIT(12)
/*
 * This driver uses a fixed calibration value in order to scale current/power
 * based on a fixed shunt resistor value. This allows for conversion within the
 * device to avoid integer limits whilst current/power accuracy is scaled
 * relative to the shunt resistor value within the driver. This is similar to
 * how the ina2xx driver handles current/power scaling.
 *
 * To achieve the best possible dynamic range, the value of the shunt voltage
 * register should match the value of the current register. With that, the shunt
 * voltage of 0x7fff = 32,767 uV = 163,785 uV matches the maximum current,
 * and no accuracy is lost. Experiments with a real chip show that this is
 * achieved by setting the SHUNT_CAL register to a value of 0x1000 = 4,096.
 * Per datasheet,
 *  SHUNT_CAL = 819.2 x 10^6 x CURRENT_LSB x Rshunt
 *            = 819,200,000 x CURRENT_LSB x Rshunt
 * With SHUNT_CAL set to 4,096, we get
 *  CURRENT_LSB = 4,096 / (819,200,000 x Rshunt)
 * Assuming an Rshunt value of 5 mOhm, we get
 *  CURRENT_LSB = 4,096 / (819,200,000 x 0.005) = 1mA
 * and thus a dynamic range of 1mA ... 32,767mA, which is sufficient for most
 * applications. The actual dynamic range is of course determined by the actual
 * shunt resistor value.
 *
 * Power and energy values are scaled accordingly.
 */
#define INA238_CALIBRATION_VALUE	4096
#define INA238_FIXED_SHUNT		5000

#define INA238_SHUNT_VOLTAGE_LSB	5000	/* 5 uV/lsb, in nV */
#define INA238_BUS_VOLTAGE_LSB		3125000	/* 3.125 mV/lsb, in nV */
#define SQ52206_BUS_VOLTAGE_LSB		3750000	/* 3.75 mV/lsb, in nV */

#define NUNIT_PER_MUNIT		1000000	/* n[AV] -> m[AV] */

static const struct regmap_config ina238_regmap_config = {
	.max_register = INA238_REGISTERS,
	.reg_bits = 8,
	.val_bits = 16,
};

enum ina238_ids { ina228, ina237, ina238, ina700, ina780, sq52206 };

struct ina238_config {
	bool has_20bit_voltage_current; /* vshunt, vbus and current are 20-bit fields */
	bool has_power_highest;		/* chip detection power peak */
	bool has_energy;		/* chip detection energy */
	u8 temp_resolution;		/* temperature register resolution in bit */
	u16 config_default;		/* Power-on default state */
	u32 power_calculate_factor;	/* fixed parameter for power calculation, from datasheet */
	u32 bus_voltage_lsb;		/* bus voltage LSB, in nV */
	int current_lsb;		/* current LSB, in uA */
};

struct ina238_data {
	const struct ina238_config *config;
	struct i2c_client *client;
	struct regmap *regmap;
	u32 rshunt;
	int gain;
	u32 voltage_lsb[2];		/* shunt, bus voltage LSB, in nV */
	int current_lsb;		/* current LSB, in uA */
	int power_lsb;			/* power LSB, in uW */
	int energy_lsb;			/* energy LSB, in uJ */
};

static const struct ina238_config ina238_config[] = {
	[ina228] = {
		.has_20bit_voltage_current = true,
		.has_energy = true,
		.has_power_highest = false,
		.power_calculate_factor = 20,
		.config_default = INA238_CONFIG_DEFAULT,
		.bus_voltage_lsb = INA238_BUS_VOLTAGE_LSB,
		.temp_resolution = 16,
	},
	[ina237] = {
		.has_20bit_voltage_current = false,
		.has_energy = false,
		.has_power_highest = false,
		.power_calculate_factor = 20,
		.config_default = INA238_CONFIG_DEFAULT,
		.bus_voltage_lsb = INA238_BUS_VOLTAGE_LSB,
		.temp_resolution = 12,
	},
	[ina238] = {
		.has_20bit_voltage_current = false,
		.has_energy = false,
		.has_power_highest = false,
		.power_calculate_factor = 20,
		.config_default = INA238_CONFIG_DEFAULT,
		.bus_voltage_lsb = INA238_BUS_VOLTAGE_LSB,
		.temp_resolution = 12,
	},
	[ina700] = {
		.has_20bit_voltage_current = false,
		.has_energy = true,
		.has_power_highest = false,
		.power_calculate_factor = 20,
		.config_default = INA238_CONFIG_DEFAULT,
		.bus_voltage_lsb = INA238_BUS_VOLTAGE_LSB,
		.temp_resolution = 12,
		.current_lsb = 480,
	},
	[ina780] = {
		.has_20bit_voltage_current = false,
		.has_energy = true,
		.has_power_highest = false,
		.power_calculate_factor = 20,
		.config_default = INA238_CONFIG_DEFAULT,
		.bus_voltage_lsb = INA238_BUS_VOLTAGE_LSB,
		.temp_resolution = 12,
		.current_lsb = 2400,
	},
	[sq52206] = {
		.has_20bit_voltage_current = false,
		.has_energy = true,
		.has_power_highest = true,
		.power_calculate_factor = 24,
		.config_default = SQ52206_CONFIG_DEFAULT,
		.bus_voltage_lsb = SQ52206_BUS_VOLTAGE_LSB,
		.temp_resolution = 16,
	},
};

static int ina238_read_reg24(const struct i2c_client *client, u8 reg, u32 *val)
{
	u8 data[3];
	int err;

	/* 24-bit register read */
	err = i2c_smbus_read_i2c_block_data(client, reg, 3, data);
	if (err < 0)
		return err;
	if (err != 3)
		return -EIO;
	*val = (data[0] << 16)