zephyr/drivers/sensor/max17055/max17055.c

/*
 * Copyright 2020 Google LLC
 *
 * SPDX-License-Identifier: Apache-2.0
 */

#include <drivers/i2c.h>
#include <drivers/sensor.h>

#include <logging/log.h>
LOG_MODULE_REGISTER(max17055, CONFIG_SENSOR_LOG_LEVEL);

#include "max17055.h"

#define DT_DRV_COMPAT maxim_max17055

/**
 * @brief Read a register value
 *
 * Registers have an address and a 16-bit value
 *
 * @param priv Private data for the driver
 * @param reg_addr Register address to read
 * @param val Place to put the value on success
 * @return 0 if successful, or negative error code from I2C API
 */
static int max17055_reg_read(struct max17055_data *priv, int reg_addr,
			     int16_t *valp)
{
	uint8_t i2c_data[2];
	int rc;

	rc = i2c_burst_read(priv->i2c, DT_INST_REG_ADDR(0), reg_addr,
			    i2c_data, 2);
	if (rc < 0) {
		LOG_ERR("Unable to read register");
		return rc;
	}
	*valp = (i2c_data[1] << 8) | i2c_data[0];

	return 0;
}

/**
 * @brief Convert capacity in MAX17055 units to milliamps
 *
 * @param rsense_mohms Value of Rsense in milliohms
 * @param val Value to convert (taken from a MAX17055 register)
 * @return corresponding value in milliamps
 */
static int capacity_to_ma(unsigned int rsense_mohms, int16_t val)
{
	int lsb_units, rem;

	/* Get units for the LSB in uA */
	lsb_units = 5 * 1000 / rsense_mohms;
	/* Get remaining capacity in uA */
	rem = val * lsb_units;

	return rem;
}

static void set_millis(struct sensor_value *val, int val_millis)
{
	val->val1 = val_millis / 1000;
	val->val2 = (val_millis % 1000) * 1000;
}

/**
 * @brief sensor value get
 *
 * @param dev MAX17055 device to access
 * @param chan Channel number to read
 * @param valp Returns the sensor value read on success
 * @return 0 if successful
 * @return -ENOTSUP for unsupported channels
 */
static int max17055_channel_get(struct device *dev, enum sensor_channel chan,
				struct sensor_value *valp)
{
	const struct max17055_config *const config = dev->config_info;
	struct max17055_data *const priv = dev->driver_data;
	unsigned int tmp;

	switch (chan) {
	case SENSOR_CHAN_GAUGE_VOLTAGE:
		/* Get voltage in uV */
		tmp = priv->voltage * 1250 / 16;
		valp->val1 = tmp / 1000000;
		valp->val2 = tmp % 1000000;
		break;
	case SENSOR_CHAN_GAUGE_AVG_CURRENT: {
		int cap_ma;

		cap_ma = capacity_to_ma(config->rsense_mohms,
					priv->avg_current);
		set_millis(valp, cap_ma);
		break;
	}
	case SENSOR_CHAN_GAUGE_STATE_OF_CHARGE:
		valp->val1 = priv->state_of_charge / 256;
		valp->val2 = priv->state_of_charge % 256 * 1000000 / 256;
		break;
	case SENSOR_CHAN_GAUGE_TEMP:
		valp->val1 = priv->internal_temp / 256;
		valp->val2 = priv->internal_temp % 256 * 1000000 / 256;
		break;
	case SENSOR_CHAN_GAUGE_FULL_CHARGE_CAPACITY:
		tmp = capacity_to_ma(config->rsense_mohms, priv->full_cap);
		set_millis(valp, tmp);
		break;
	case SENSOR_CHAN_GAUGE_REMAINING_CHARGE_CAPACITY:
		tmp = capacity_to_ma(config->rsense_mohms, priv->remaining_cap);
		set_millis(valp, tmp);
		break;
	case SENSOR_CHAN_GAUGE_TIME_TO_EMPTY:
		/* Get time in ms */
		if (priv->time_to_empty == 0xffff) {
			valp->val1 = 0;
			valp->val2 = 0;
		} else {
			tmp = priv->time_to_empty * 5625;
			set_millis(valp, tmp);
		}
		break;
	case SENSOR_CHAN_GAUGE_TIME_TO_FULL:
		if (priv->time_to_full == 0xffff) {
			valp->val1 = 0;
			valp->val2 = 0;
		} else {
			/* Get time in ms */
			tmp = priv->time_to_full * 5625;
			set_millis(valp, tmp);
		}
		break;
	case SENSOR_CHAN_GAUGE_CYCLE_COUNT:
		valp->val1 = priv->cycle_count / 100;
		valp->val2 = priv->cycle_count % 100 * 10000;
		break;
	case SENSOR_CHAN_GAUGE_NOM_AVAIL_CAPACITY:
		tmp = capacity_to_ma(config->rsense_mohms, priv->design_cap);
		set_millis(valp, tmp);
		break;
	case SENSOR_CHAN_GAUGE_DESIGN_VOLTAGE:
		set_millis(valp, config->design_voltage);
		break;
	case SENSOR_CHAN_GAUGE_DESIRED_VOLTAGE:
		set_millis(valp, config->desired_voltage);
		break;
	case SENSOR_CHAN_GAUGE_DESIRED_CHARGING_CURRENT:
		valp->val1 = config->desired_charging_current;
		valp->val2 = 0;
		break;
	default:
		return -ENOTSUP;
	}

	return 0;
}

static int max17055_sample_fetch(struct device *dev, enum sensor_channel chan)
{
	struct max17055_data *priv = dev->driver_data;
	struct {
		int reg_addr;
		int16_t *dest;
	} regs[] = {
		{ VCELL, &priv->voltage },
		{ AVG_CURRENT, &priv->avg_current },
		{ REP_SOC, &priv->state_of_charge },
		{ INT_TEMP, &priv->internal_temp },
		{ REP_CAP, &priv->remaining_cap },
		{ FULL_CAP_REP, &priv->full_cap },
		{ TTE, &priv->time_to_empty },
		{ TTF, &priv->time_to_full },
		{ CYCLES, &priv->cycle_count },
		{ DESIGN_CAP, &priv->design_cap },
	};

	__ASSERT_NO_MSG(chan == SENSOR_CHAN_ALL);
	for (size_t i = 0; i < ARRAY_SIZE(regs); i++) {
		int rc;

		rc = max17055_reg_read(priv, regs[i].reg_addr, regs[i].dest);
		if (rc != 0) {
			LOG_ERR("Failed to read channel %d", chan);
			return rc;
		}
	}

	return 0;
}

/**
 * @brief initialise the fuel gauge
 *
 * @return 0 for success
 * @return -EINVAL if the I2C controller could not be found
 */
static int max17055_gauge_init(struct device *dev)
{
	struct max17055_data *priv = dev->driver_data;
	const struct max17055_config *const config = dev->config_info;

	priv->i2c = device_get_binding(config->bus_name);
	if (!priv->i2c) {
		LOG_ERR("Could not get pointer to %s device", config->bus_name);
		return -EINVAL;
	}

	return 0;
}

static const struct sensor_driver_api max17055_battery_driver_api = {
	.sample_fetch = max17055_sample_fetch,
	.channel_get = max17055_channel_get,
};

#define MAX17055_INIT(index)						\
	static struct max17055_data max17055_driver_##index;		\
									\
	static const struct max17055_config max17055_config_##index = { \
		.bus_name = DT_INST_BUS_LABEL(index),			\
		.rsense_mohms = DT_INST_PROP(index, rsense_mohms),	\
		.design_voltage = DT_INST_PROP(index, design_voltage),	\
		.desired_voltage = DT_INST_PROP(index, desired_voltage), \
		.desired_charging_current =				\
			DT_INST_PROP(index, desired_charging_current),	\
	};								\
									\
	DEVICE_AND_API_INIT(max17055_##index, DT_INST_LABEL(index),	\
			    &max17055_gauge_init, &max17055_driver_##index, \
			    &max17055_config_##index, POST_KERNEL,	\
			    CONFIG_SENSOR_INIT_PRIORITY,		\
			    &max17055_battery_driver_api)

DT_INST_FOREACH_STATUS_OKAY(MAX17055_INIT);