// SPDX-License-Identifier: GPL-2.0
/*
 * Driver for Texas Instruments TMP512, TMP513 power monitor chips
 *
 * TMP513:
 * Thermal/Power Management with Triple Remote and
 * Local Temperature Sensor and Current Shunt Monitor
 * Datasheet: https://www.ti.com/lit/gpn/tmp513
 *
 * TMP512:
 * Thermal/Power Management with Dual Remote
 *	and Local Temperature Sensor and Current Shunt Monitor
 * Datasheet: https://www.ti.com/lit/gpn/tmp512
 *
 * Copyright (C) 2019 Eric Tremblay <etremblay@distech-controls.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; version 2 of the License.
 */

#include <linux/bitops.h>
#include <linux/bug.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/hwmon.h>
#include <linux/i2c.h>
#include <linux/init.h>
#include <linux/math.h>
#include <linux/module.h>
#include <linux/property.h>
#include <linux/regmap.h>
#include <linux/slab.h>
#include <linux/types.h>
#include <linux/units.h>

// Common register definition
#define TMP51X_SHUNT_CONFIG		0x00
#define TMP51X_TEMP_CONFIG		0x01
#define TMP51X_STATUS			0x02
#define TMP51X_SMBUS_ALERT		0x03
#define TMP51X_SHUNT_CURRENT_RESULT	0x04
#define TMP51X_BUS_VOLTAGE_RESULT	0x05
#define TMP51X_POWER_RESULT		0x06
#define TMP51X_BUS_CURRENT_RESULT	0x07
#define TMP51X_LOCAL_TEMP_RESULT	0x08
#define TMP51X_REMOTE_TEMP_RESULT_1	0x09
#define TMP51X_REMOTE_TEMP_RESULT_2	0x0A
#define TMP51X_SHUNT_CURRENT_H_LIMIT	0x0C
#define TMP51X_SHUNT_CURRENT_L_LIMIT	0x0D
#define TMP51X_BUS_VOLTAGE_H_LIMIT	0x0E
#define TMP51X_BUS_VOLTAGE_L_LIMIT	0x0F
#define TMP51X_POWER_LIMIT		0x10
#define TMP51X_LOCAL_TEMP_LIMIT	0x11
#define TMP51X_REMOTE_TEMP_LIMIT_1	0x12
#define TMP51X_REMOTE_TEMP_LIMIT_2	0x13
#define TMP51X_SHUNT_CALIBRATION	0x15
#define TMP51X_N_FACTOR_AND_HYST_1	0x16
#define TMP51X_N_FACTOR_2		0x17
#define TMP51X_MAN_ID_REG		0xFE
#define TMP51X_DEVICE_ID_REG		0xFF

// TMP513 specific register definition
#define TMP513_REMOTE_TEMP_RESULT_3	0x0B
#define TMP513_REMOTE_TEMP_LIMIT_3	0x14
#define TMP513_N_FACTOR_3		0x18

// Common attrs, and NULL
#define TMP51X_MANUFACTURER_ID		0x55FF

#define TMP512_DEVICE_ID		0x22FF
#define TMP513_DEVICE_ID		0x23FF

// Default config
#define TMP51X_SHUNT_CONFIG_DEFAULT	0x399F
#define TMP51X_SHUNT_VALUE_DEFAULT	1000
#define TMP51X_VBUS_RANGE_DEFAULT	TMP51X_VBUS_RANGE_32V
#define TMP51X_PGA_DEFAULT		8
#define TMP51X_MAX_REGISTER_ADDR	0xFF

// Mask and shift
#define CURRENT_SENSE_VOLTAGE_320_MASK	0x1800
#define CURRENT_SENSE_VOLTAGE_160_MASK	0x1000
#define CURRENT_SENSE_VOLTAGE_80_MASK	0x0800
#define CURRENT_SENSE_VOLTAGE_40_MASK	0

#define TMP51X_BUS_VOLTAGE_MASK		0x2000
#define TMP51X_NFACTOR_MASK		0xFF00
#define TMP51X_HYST_MASK		0x00FF

#define TMP51X_BUS_VOLTAGE_SHIFT	3
#define TMP51X_TEMP_SHIFT		3

// Alarms
#define TMP51X_SHUNT_CURRENT_H_LIMIT_POS	15
#define TMP51X_SHUNT_CURRENT_L_LIMIT_POS	14
#define TMP51X_BUS_VOLTAGE_H_LIMIT_POS		13
#define TMP51X_BUS_VOLTAGE_L_LIMIT_POS		12
#define TMP51X_POWER_LIMIT_POS			11
#define TMP51X_LOCAL_TEMP_LIMIT_POS		10
#define TMP51X_REMOTE_TEMP_LIMIT_1_POS		9
#define TMP51X_REMOTE_TEMP_LIMIT_2_POS		8
#define TMP513_REMOTE_TEMP_LIMIT_3_POS		7

#define TMP51X_VBUS_RANGE_32V		(32 * MICRO)
#define TMP51X_VBUS_RANGE_16V		(16 * MICRO)

// Max and Min value
#define MAX_BUS_VOLTAGE_32_LIMIT	32764
#define MAX_BUS_VOLTAGE_16_LIMIT	16382

// Max possible value is -256 to +256 but datasheet indicated -40 to 125.
#define MAX_TEMP_LIMIT			125000
#define MIN_TEMP_LIMIT			-40000

#define MAX_TEMP_HYST			127500

#define TMP512_MAX_CHANNELS		3
#define TMP513_MAX_CHANNELS		4

#define TMP51X_TEMP_CONFIG_CONV_RATE	GENMASK(9, 7)
#define TMP51X_TEMP_CONFIG_RC		BIT(10)
#define TMP51X_TEMP_CHANNEL_MASK(n)	(GENMASK((n) - 1, 0) << 11)
#define TMP51X_TEMP_CONFIG_CONT		BIT(15)
#define TMP51X_TEMP_CONFIG_DEFAULT(n)					\
	(TMP51X_TEMP_CHANNEL_MASK(n) | TMP51X_TEMP_CONFIG_CONT |	\
	 TMP51X_TEMP_CONFIG_CONV_RATE | TMP51X_TEMP_CONFIG_RC)

static const u8 TMP51X_TEMP_INPUT[4] = {
	TMP51X_LOCAL_TEMP_RESULT,
	TMP51X_REMOTE_TEMP_RESULT_1,
	TMP51X_REMOTE_TEMP_RESULT_2,
	TMP513_REMOTE_TEMP_RESULT_3
};

static const u8 TMP51X_TEMP_CRIT[4] = {
	TMP51X_LOCAL_TEMP_LIMIT,
	TMP51X_REMOTE_TEMP_LIMIT_1,
	TMP51X_REMOTE_TEMP_LIMIT_2,
	TMP513_REMOTE_TEMP_LIMIT_3
};

static const u8 TMP51X_TEMP_CRIT_ALARM[4] = {
	TMP51X_LOCAL_TEMP_LIMIT_POS,
	TMP51X_REMOTE_TEMP_LIMIT_1_POS,
	TMP51X_REMOTE_TEMP_LIMIT_2_POS,
	TMP513_REMOTE_TEMP_LIMIT_3_POS
};

static const u8 TMP51X_TEMP_CRIT_HYST[4] = {
	TMP51X_N_FACTOR_AND_HYST_1,
	TMP51X_N_FACTOR_AND_HYST_1,
	TMP51X_N_FACTOR_AND_HYST_1,
	TMP51X_N_FACTOR_AND_HYST_1
};

static const u8 TMP51X_CURR_INPUT[2] = {
	TMP51X_SHUNT_CURRENT_RESULT,
	TMP51X_BUS_CURRENT_RESULT
};

static const struct regmap_config tmp51x_regmap_config = {
	.reg_bits = 8,
	.val_bits = 16,
	.max_register = TMP51X_MAX_REGISTER_ADDR,
};

struct tmp51x_data {
	u16 shunt_config;
	u16 pga_gain;
	u32 vbus_range_uvolt;

	u16 temp_config;
	u32 nfactor[3];

	u32 shunt_uohms;

	u32 curr_lsb_ua;
	u32 pwr_lsb_uw;

	u8 max_channels;
	struct regmap *regmap;
};

// Set the shift based on the gain 8=4, 4=3, 2=2, 1=1
static inline u8 tmp51x_get_pga_shift(struct tmp51x_data *data)
{
	return 5 - ffs(data->pga_gain);
}

static int tmp51x_get_value(struct tmp51x_data *data, u8 reg, u8 pos,
			    unsigned int regval, long *val)
{
	switch (reg) {
	case TMP51X_STATUS:
		*val = (regval >> pos) & 1;
		break;
	case TMP51X_SHUNT_CURRENT_RESULT:
	case TMP51X_SHUNT_CURRENT_H_LIMIT:
	case TMP51X_SHUNT_CURRENT_L_LIMIT:
		/*
		 * The valus is read in voltage in the chip but reported as
		 * current to the user.
		 * 2's complement number shifted by one to four depending
		 * on the pga gain setting. 1lsb = 10uV
		 */
		*val = sign_extend32(regval, 17 - tmp51x_get_pga_shift(data));
		*val = DIV_ROUND_CLOSEST(*val * 10 * MILLI, data->shunt_uohms);
		break;
	case TMP51X_BUS_VOLTAGE_RESULT:
	case TMP51X_BUS_VOLTAGE_H_LIMIT:
	case TMP51X_BUS_VOLTAGE_L_LIMIT:
		// 1lsb = 4mV
		*val = (regval >> TMP51X_BUS_VOLTAGE_SHIFT) * 4;
		break;
	case TMP51X_POWER_RESULT:
	case TMP51X_POWER_LIMIT:
		// Power = (current * BusVoltage) / 5000
		*val = regval * data->pwr_lsb_uw;
		break;
	case TMP51X_BUS_CURRENT_RESULT:
		// Current = (ShuntVoltage * CalibrationRegister) / 4096
		*val = sign_extend32(regval, 16) * data->curr_lsb_ua;
		*val = DIV_ROUND_CLOSEST(*val, MILLI);
		break;
	case TMP51X_LOCAL_TEMP_RESULT:
	case TMP51X_REMOTE_TEMP_RESULT_1:
	case TMP51X_REMOTE_TEMP_RESULT_2:
	case TMP513_REMOTE_TEMP_RESULT_3:
	case TMP51X_LOCAL_TEMP_LIMIT:
	case TMP51X_REMOTE_TEMP_LIMIT_1:
	case TMP51X_REMOTE_TEMP_LIMIT_2:
	case TMP513_REMOTE_TEMP_LIMIT_3:
		// 1lsb = 0.0625 degrees centigrade
		*val = sign_extend32(regval, 16) >> TMP51X_TEMP_SHIFT;
		*val = DIV_ROUND_CLOSEST(*val * 625, 10);
		break;
	case TMP51X_N_FACTOR_AND_HYST_1:
		// 1lsb = 0.5 degrees centigrade
		*val = (regval & TMP51X_HYST_MASK) * 500;
		break;
	default:
		// Programmer goofed
		WARN_ON_ONCE(1);
		*val = 0;
		return -EOPNOTSUPP;
	}

	return 0;
}

static int tmp51x_set_value(struct tmp51x_data *data, u8 reg, long val)
{
	int regval, max_val;
	u32 mask = 0;

	switch (reg) {
	case TMP51X_SHUNT_CURRENT_H_LIMIT:
	case TMP51X_SHUNT_CURRENT_L_LIMIT:
		/*
		 * The user enter current value and we convert it to
		 * voltage. 1lsb = 10uV
		 */
		val = DIV_ROUND_CLOSEST(val * data->shunt_uohms, 10 * MILLI);
		max_val = U16_MAX >> tmp51x_get_pga_shift(data);
		regval = clamp_val(val, -max_val, max_val);
		break;
	case TMP51X_BUS_VOLTAGE_H_LIMIT:
	case TMP51X_BUS_VOLTAGE_L_LIMIT:
		// 1lsb = 4mV
		max_val = (data->vbus_range_uvolt == TMP51X_VBUS_RANGE_32V) ?
			MAX_BUS_VOLTAGE_32_LIMIT : MAX_BUS_VOLTAGE_16_LIMIT;

		val = clamp_val(DIV_ROUND_CLOSEST(val, 4), 0, max_val);
		regval = val << TMP51X_BUS_VOLTAGE_SHIFT;
		break;
	case TMP51X_POWER_LIMIT:
		regval = clamp_val(DIV_ROUND_CLOSEST(val, data->pwr_lsb_uw), 0,
				   U16_MAX);
		break;
	case TMP51X_LOCAL_TEMP_LIMIT:
	case TMP51X_REMOTE_TEMP_LIMIT_1:
	case TMP51X_REMOTE_TEMP_LIMIT_2:
	case TMP513_REMOTE_TEMP_LIMIT_3:
		// 1lsb = 0.0625 degrees centigrade
		val = clamp_val(val, MIN_TEMP_LIMIT, MAX_TEMP_LIMIT);
		regval = DIV_ROUND_CLOSEST(val * 10, 625) << TMP51X_TEMP_SHIFT;
		break;
	case TMP51X_N_FACTOR_AND_HYST_1:
		// 1lsb = 0.5 degrees centigrade
		val = clamp_val(val, 0, MAX_TEMP_HYST);
		regval = DIV_ROUND_CLOSEST(val, 500);
		mask = TMP51X_HYST_MASK;
		break;
	default:
		// Programmer goofed
		WARN_ON_ONCE(1);
		return -EOPNOTSUPP;
	}

	if (mask == 0)
		return regmap_write(data->regmap, reg, regval);
	else
		return regmap_update_bits(data->regmap, reg, mask, regval);
}

static u8 tmp51x_get_reg(enum hwmon_sensor_types type, u32 attr, int channel)
{
	switch (type) {
	case hwmon_temp:
		switch (attr) {
		case hwmon_temp_input:
			return TMP51X_TEMP_INPUT[channel];
		case hwmon_temp_crit_alarm:
			return TMP51X_STATUS;
		case hwmon_temp_crit:
			return TMP51X_TEMP_CRIT[channel];
		case hwmon_temp_crit_hyst:
			return TMP51X_TEMP_CRIT_HYST[channel];
		}
		break;
	case hwmon_in:
		switch (attr) {
		case hwmon_in_input:
			return TMP51X_BUS_VOLTAGE_RESULT;
		case hwmon_in_lcrit_alarm:
		case hwmon_in_crit_alarm:
			return TMP51X_STATUS;
		case hwmon_in_lcrit:
			return TMP51X_BUS_VOLTAGE_L_LIMIT;
		case hwmon_in_crit:
			return TMP51X_BUS_VOLTAGE_H_LIMIT;
		}
		break;
	case hwmon_curr:
		switch (attr) {
		case hwmon_curr_input:
			return TMP51X_CURR_INPUT[channel];
		case hwmon_curr_lcrit_alarm:
		case hwmon_curr_crit_alarm:
			return TMP51X_STATUS;
		case hwmon_curr_lcrit:
			return TMP51X_SHUNT_CURRENT_L_LIMIT;
		case hwmon_curr_crit:
			return TMP51X_SHUNT_CURRENT_H_LIMIT;
		}
		break;
	case hwmon_power:
		switch (attr) {
		case hwmon_power_input:
			return TMP51X_POWER_RESULT;
		case hwmon_power_crit_alarm:
			return TMP51X_STATUS;
		case hwmon_power_crit:
			return TMP51X_POWER_LIMIT;
		}
		break;
	default:
		break;
	}

	return 0;
}

static u8 tmp51x_get_status_pos(enum hwmon_sensor_types type, u32 attr,
				int channel)
{
	switch (type) {
	case hwmon_temp:
		switch (attr) {
		case hwmon_temp_crit_alarm:
			return TMP51X_TEMP_CRIT_ALARM[channel];
		}
		break;
	case hwmon_in:
		switch (attr) {
		case hwmon_in_lcrit_alarm:
			return TMP51X_BUS_VOLTAGE_L_LIMIT_POS;
		case hwmon_in_crit_alarm:
			return TMP51X_BUS_VOLTAGE_H_LIMIT_POS;
		}
		break;
	case hwmon_curr:
		switch (attr) {
		case hwmon_curr_lcrit_alarm:
			return TMP51X_SHUNT_CURRENT_L_LIMIT_POS;
		case hwmon_curr_crit_alarm:
			return TMP51X_SHUNT_CURRENT_H_LIMIT_POS;
		}
		break;
	case hwmon_power:
		switch (attr) {
		case hwmon_power_crit_alarm:
			return TMP51X_POWER_LIMIT_POS;
		}
		break;
	default:
		break;
	}

	return 0;
}

static int tmp51x_read(struct device *dev, enum hwmon_sensor_types type,
		       u32 attr, int channel, long *val)
{
	struct tmp51x_data *data = dev_get_drvdata(dev);
	int ret;
	u32 regval;
	u8 pos = 0, reg = 0;

	reg = tmp51x_get_reg(type, attr, channel);
	if (reg == 0)
		return -EOPNOTSUPP;

	if (reg == TMP51X_STATUS)
		pos = tmp51x_get_status_pos(type, attr, channel);

	ret = regmap_read(data->regmap, reg, &regval);
	if (ret < 0)
		return ret;

	return tmp51x_get_value(data, reg, pos, regval, val);
}

static int tmp51x_write(struct device *dev, enum hwmon_sensor_types type,
			u32 attr, int channel, long val)
{
	u8 reg = 0;

	reg = tmp51x_get_reg(type, attr, channel);
	if (reg == 0)
		return -EOPNOTSUPP;

	return tmp51x_set_value(dev_get_drvdata(dev), reg, val);
}

static umode_t tmp51x_is_visible(const void *_data,
				 enum hwmon_sensor_types type, u32 attr,
				 int channel)
{
	const struct tmp51x_data *data = _data;

	switch (type) {
	case hwmon_temp:
		if (channel >= data->max_channels)
			return 0;
		switch (attr) {
		case hwmon_temp_input:
		case hwmon_temp_crit_alarm:
			return 0444;
		case hwmon_temp_crit:
			return 0644;
		case hwmon_temp_crit_hyst:
			if (channel == 0)
				return 0644;
			return 0444;
		}
		break;
	case hwmon_in:
		switch (attr) {
		case hwmon_in_input:
		case hwmon_in_lcrit_alarm:
		case hwmon_in_crit_alarm:
			return 0444;
		case hwmon_in_lcrit:
		case hwmon_in_crit:
			return 0644;
		}
		break;
	case hwmon_curr:
		if (!data->shunt_uohms)
			return 0;

		switch (attr) {
		case hwmon_curr_input:
		case hwmon_curr_lcrit_alarm:
		case hwmon_curr_crit_alarm:
			return 0444;
		case hwmon_curr_lcrit:
		case hwmon_curr_crit:
			return 0644;
		}
		break;
	case hwmon_power:
		if (!data->shunt_uohms)
			return 0;

		switch (attr) {
		case hwmon_power_input:
		case hwmon_power_crit_alarm:
			return 0444;
		case hwmon_power_crit:
			return 0644;
		}
		break;
	default:
		break;
	}
	return 0;
}

static const struct hwmon_channel_info * const tmp51x_info[] = {
	HWMON_CHANNEL_INFO(temp,
			   HWMON_T_INPUT | HWMON_T_CRIT | HWMON_T_CRIT_ALARM |
			   HWMON_T_CRIT_HYST,
			   HWMON_T_INPUT | HWMON_T_CRIT | HWMON_T_CRIT_ALARM |
			   HWMON_T_CRIT_HYST,
			   HWMON_T_INPUT | HWMON_T_CRIT | HWMON_T_CRIT_ALARM |
			   HWMON_T_CRIT_HYST,
			   HWMON_T_INPUT | HWMON_T_CRIT | HWMON_T_CRIT_ALARM |
			   HWMON_T_CRIT_HYST),
	HWMON_CHANNEL_INFO(in,
			   HWMON_I_INPUT | HWMON_I_LCRIT | HWMON_I_LCRIT_ALARM |
			   HWMON_I_CRIT | HWMON_I_CRIT_ALARM),
	HWMON_CHANNEL_INFO(curr,
			   HWMON_C_INPUT | HWMON_C_LCRIT | HWMON_C_LCRIT_ALARM |
			   HWMON_C_CRIT | HWMON_C_CRIT_ALARM,
			   HWMON_C_INPUT),
	HWMON_CHANNEL_INFO(power,
			   HWMON_P_INPUT | HWMON_P_CRIT | HWMON_P_CRIT_ALARM),
	NULL
};

static const struct hwmon_ops tmp51x_hwmon_ops = {
	.is_visible = tmp51x_is_visible,
	.read = tmp51x_read,
	.write = tmp51x_write,
};

static const struct hwmon_chip_info tmp51x_chip_info = {
	.ops = &tmp51x_hwmon_ops,
	.info = tmp51x_info,
};

/*
 * Calibrate the tmp51x following the datasheet method
 */
static int tmp51x_calibrate(struct tmp51x_data *data)
{
	int vshunt_max = data->pga_gain * 40;
	u64 max_curr_ma;
	u32 div;

	/*
	 * If shunt_uohms is equal to 0, the calibration should be set to 0.
	 * The consequence will be that the current and power measurement engine
	 * of the sensor will not work. Temperature and voltage sensing will
	 * continue to work.
	 */
	if (data->shunt_uohms == 0)
		return regmap_write(data->regmap, TMP51X_SHUNT_CALIBRATION, 0);

	max_curr_ma = DIV_ROUND_CLOSEST_ULL(vshunt_max * MICRO, data->shunt_uohms);

	/*
	 * Calculate the minimal bit resolution for the current and the power.
	 * Those values will be used during register interpretation.
	 */
	data->curr_lsb_ua = DIV_ROUND_CLOSEST_ULL(max_curr_ma * MILLI, 32767);
	data->pwr_lsb_uw = 20 * data->curr_lsb_ua;

	div = DIV_ROUND_CLOSEST_ULL(data->curr_lsb_ua * data->shunt_uohms, MICRO);

	return regmap_write(data->regmap, TMP51X_SHUNT_CALIBRATION,
			    DIV_ROUND_CLOSEST(40960, div));
}

/*
 * Initialize the configuration and calibration registers.
 */
static int tmp51x_init(struct tmp51x_data *data)
{
	unsigned int regval;
	int ret = regmap_write(data->regmap, TMP51X_SHUNT_CONFIG,
			       data->shunt_config);
	if (ret < 0)
		return ret;

	ret = regmap_write(data->regmap, TMP51X_TEMP_CONFIG, data->temp_config);
	if (ret < 0)
		return ret;

	// nFactor configuration
	ret = regmap_update_bits(data->regmap, TMP51X_N_FACTOR_AND_HYST_1,
				 TMP51X_NFACTOR_MASK, data->nfactor[0] << 8);
	if (ret < 0)
		return ret;

	ret = regmap_write(data->regmap, TMP51X_N_FACTOR_2,
			   data->nfactor[1] << 8);
	if (ret < 0)
		return ret;

	if (data->max_channels == TMP513_MAX_CHANNELS) {
		ret = regmap_write(data->regmap, TMP513_N_FACTOR_3,
				   data->nfactor[2] << 8);
		if (ret < 0)
			return ret;
	}

	ret = tmp51x_calibrate(data);
	if (ret < 0)
		return ret;

	// Read the status register before using as the datasheet propose
	return regmap_read(data->regmap, TMP51X_STATUS, &regval);
}

static const struct i2c_device_id tmp51x_id[] = {
	{ "tmp512", TMP512_MAX_CHANNELS },
	{ "tmp513", TMP513_MAX_CHANNELS },
	{ }
};
MODULE_DEVICE_TABLE(i2c, tmp51x_id);

static const struct of_device_id tmp51x_of_match[] = {
	{ .compatible = "ti,tmp512", .data = (void *)TMP512_MAX_CHANNELS },
	{ .compatible = "ti,tmp513", .data = (void *)TMP513_MAX_CHANNELS },
	{ }
};
MODULE_DEVICE_TABLE(of, tmp51x_of_match);

static int tmp51x_vbus_range_to_reg(struct device *dev,
				    struct tmp51x_data *data)
{
	if (data->vbus_range_uvolt == TMP51X_VBUS_RANGE_32V) {
		data->shunt_config |= TMP51X_BUS_VOLTAGE_MASK;
	} else if (data->vbus_range_uvolt == TMP51X_VBUS_RANGE_16V) {
		data->shunt_config &= ~TMP51X_BUS_VOLTAGE_MASK;
	} else {
		return dev_err_probe(dev, -EINVAL,
				     "ti,bus-range-microvolt is invalid: %u\n",
				     data->vbus_range_uvolt);
	}
	return 0;
}

static int tmp51x_pga_gain_to_reg(struct device *dev, struct tmp51x_data *data)
{
	if (data->pga_gain == 8) {
		data->shunt_config |= CURRENT_SENSE_VOLTAGE_320_MASK;
	} else if (data->pga_gain == 4) {
		data->shunt_config |= CURRENT_SENSE_VOLTAGE_160_MASK;
	} else if (data->pga_gain == 2) {
		data->shunt_config |= CURRENT_SENSE_VOLTAGE_80_MASK;
	} else if (data->pga_gain == 1) {
		data->shunt_config |= CURRENT_SENSE_VOLTAGE_40_MASK;
	} else {
		return dev_err_probe(dev, -EINVAL,
				     "ti,pga-gain is invalid: %u\n", data->pga_gain);
	}
	return 0;
}

static int tmp51x_read_properties(struct device *dev, struct tmp51x_data *data)
{
	int ret;
	u32 val;

	ret = device_property_read_u32(dev, "shunt-resistor-micro-ohms", &val);
	data->shunt_uohms = (ret >= 0) ? val : TMP51X_SHUNT_VALUE_DEFAULT;

	ret = device_property_read_u32(dev, "ti,bus-range-microvolt", &val);
	data->vbus_range_uvolt = (ret >= 0) ? val : TMP51X_VBUS_RANGE_DEFAULT;
	ret = tmp51x_vbus_range_to_reg(dev, data);
	if (ret < 0)
		return ret;

	ret = device_property_read_u32(dev, "ti,pga-gain", &val);
	data->pga_gain = (ret >= 0) ? val : TMP51X_PGA_DEFAULT;
	ret = tmp51x_pga_gain_to_reg(dev, data);
	if (ret < 0)
		return ret;

	device_property_read_u32_array(dev, "ti,nfactor", data->nfactor,
				       data->max_channels - 1);

	// Check if shunt value is compatible with pga-gain
	if (data->shunt_uohms > data->pga_gain * 40 * MICRO) {
		return dev_err_probe(dev, -EINVAL,
				     "shunt-resistor: %u too big for pga_gain: %u\n",
				     data->shunt_uohms, data->pga_gain);
	}

	return 0;
}

static void tmp51x_use_default(struct tmp51x_data *data)
{
	data->vbus_range_uvolt = TMP51X_VBUS_RANGE_DEFAULT;
	data->pga_gain = TMP51X_PGA_DEFAULT;
	data->shunt_uohms = TMP51X_SHUNT_VALUE_DEFAULT;
}

static int tmp51x_configure(struct device *dev, struct tmp51x_data *data)
{
	data->shunt_config = TMP51X_SHUNT_CONFIG_DEFAULT;
	data->temp_config = TMP51X_TEMP_CONFIG_DEFAULT(data->max_channels);

	if (dev->of_node)
		return tmp51x_read_properties(dev, data);

	tmp51x_use_default(data);

	return 0;
}

static int tmp51x_probe(struct i2c_client *client)
{
	struct device *dev = &client->dev;
	struct tmp51x_data *data;
	struct device *hwmon_dev;
	int ret;

	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
	if (!data)
		return -ENOMEM;

	data->max_channels = (uintptr_t)i2c_get_match_data(client);

	ret = tmp51x_configure(dev, data);
	if (ret < 0)
		return dev_err_probe(dev, ret, "error configuring the device\n");

	data->regmap = devm_regmap_init_i2c(client, &tmp51x_regmap_config);
	if (IS_ERR(data->regmap))
		return dev_err_probe(dev, PTR_ERR(data->regmap),
				     "failed to allocate register map\n");

	ret = tmp51x_init(data);
	if (ret < 0)
		return dev_err_probe(dev, ret, "error configuring the device\n");

	hwmon_dev = devm_hwmon_device_register_with_info(dev, client->name,
							 data,
							 &tmp51x_chip_info,
							 NULL);
	if (IS_ERR(hwmon_dev))
		return PTR_ERR(hwmon_dev);

	dev_dbg(dev, "power monitor %s\n", client->name);

	return 0;
}

static struct i2c_driver tmp51x_driver = {
	.driver = {
		.name	= "tmp51x",
		.of_match_table = tmp51x_of_match,
	},
	.probe		= tmp51x_probe,
	.id_table	= tmp51x_id,
};

module_i2c_driver(tmp51x_driver);

MODULE_AUTHOR("Eric Tremblay <etremblay@distechcontrols.com>");
MODULE_DESCRIPTION("tmp51x driver");
MODULE_LICENSE("GPL");