drivers: Add fuel gauge max17043

drivers/fuel_gauge/CMakeLists.txt

@@ -5,6 +5,7 @@ zephyr_syscall_header(${ZEPHYR_BASE}/include/zephyr/drivers/fuel_gauge.h)
 add_subdirectory_ifdef(CONFIG_SBS_GAUGE_NEW_API		sbs_gauge)
 add_subdirectory_ifdef(CONFIG_FUEL_GAUGE_COMPOSITE	composite)
 add_subdirectory_ifdef(CONFIG_MAX17048		max17048)
+add_subdirectory_ifdef(CONFIG_MAX17043		max17043)
 add_subdirectory_ifdef(CONFIG_BQ27Z746		bq27z746)
 add_subdirectory_ifdef(CONFIG_FUEL_GAUGE_AXP2101	axp2101)
 add_subdirectory_ifdef(CONFIG_LC709203F		lc709203f)

drivers/fuel_gauge/Kconfig

@@ -19,6 +19,7 @@ config FUEL_GAUGE_INIT_PRIORITY
 	help
 	  Battery fuel gauge initialization priority.
 
+source "drivers/fuel_gauge/max17043/Kconfig"
 source "drivers/fuel_gauge/max17048/Kconfig"
 source "drivers/fuel_gauge/sbs_gauge/Kconfig"
 source "drivers/fuel_gauge/bq27z746/Kconfig"

drivers/fuel_gauge/max17043/Kconfig

@@ -0,0 +1,13 @@
+# MAX17043 Li-Ion battery fuel gauge
+
+# Copyright (c) 2025, Mohammed Billoo <mab@mab-labs.com>
+# SPDX-License-Identifier: Apache-2.0
+
+
+config MAX17043
+	bool "MAX17043 Li-Po fuel gauge"
+	default y
+	depends on DT_HAS_MAXIM_MAX17043_ENABLED
+	select I2C
+	help
+	  Enable driver for the MAX17043 fuel gauge device.

drivers/fuel_gauge/max17043/max17043.c

@@ -0,0 +1,177 @@
+/* max17043.c - Driver for max17043 battery fuel gauge */
+
+/*
+ * Copyright (c) 2025  Mohammed Billoo <mab@mab-labs.com>
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#define DT_DRV_COMPAT maxim_max17043
+
+#include "max17043.h"
+
+#include <zephyr/logging/log.h>
+#include <zephyr/drivers/fuel_gauge.h>
+#include <zephyr/kernel.h>
+#include <zephyr/init.h>
+#include <zephyr/pm/device.h>
+#include <zephyr/sys/byteorder.h>
+#include <zephyr/sys/__assert.h>
+
+LOG_MODULE_REGISTER(MAX17043);
+
+#if DT_NUM_INST_STATUS_OKAY(DT_DRV_COMPAT) == 0
+#warning "MAX17043 driver enabled without any devices"
+#endif
+
+/**
+ * Storage for the fuel gauge basic information
+ */
+struct max17043_data {
+	/* Charge as percentage */
+	uint8_t charge;
+	/* Voltage as uV */
+	uint32_t voltage;
+};
+
+/**
+ * I2C communication
+ * The way we read a value is first writing the address we want to read and then
+ * wait for 2 bytes containing the data.
+ */
+int max17043_read_register(const struct device *dev, uint8_t registerId, uint16_t *response)
+{
+	uint8_t max17043_buffer[2];
+	const struct max17043_config *cfg = dev->config;
+	int rc = i2c_write_read_dt(&cfg->i2c, &registerId, sizeof(registerId), max17043_buffer,
+				   sizeof(max17043_buffer));
+	if (rc != 0) {
+		LOG_ERR("Unable to read register, error %d", rc);
+		return rc;
+	}
+
+	*response = sys_get_be16(max17043_buffer);
+	return 0;
+}
+
+/**
+ * Raw value from the internal ADC
+ */
+int max17043_adc(const struct device *i2c_dev, uint16_t *response)
+{
+	return max17043_read_register(i2c_dev, REGISTER_VCELL, response);
+}
+
+/**
+ * Battery voltage
+ */
+int max17043_voltage(const struct device *i2c_dev, uint32_t *response)
+{
+	uint16_t raw_voltage;
+	int rc = max17043_adc(i2c_dev, &raw_voltage);
+
+	if (rc < 0) {
+		return rc;
+	}
+	/**
+	 * Once the value is read, it has to be converted to volts. The datasheet
+	 * https://www.analog.com/media/en/technical-documentation/data-sheets/
+	 * MAX17043-MAX17049.pdf
+	 * Page 10, Table 2. Register Summary: 78.125µV/cell
+	 * Max17043 only supports one cell so we just have to multiply the value by 78.125 to
+	 * obtain µV
+	 */
+
+	*response = (uint32_t)raw_voltage * 78.125;
+	return 0;
+}
+
+/**
+ * Battery percentage still available
+ */
+int max17043_percent(const struct device *i2c_dev, uint8_t *response)
+{
+	uint16_t data;
+	int rc = max17043_read_register(i2c_dev, REGISTER_SOC, &data);
+
+	if (rc < 0) {
+		return rc;
+	}
+	/**
+	 * Once the value is read, it has to be converted to percentage. The datasheet
+	 * Page 8, Table 2. Register Summary: 1%/256
+	 * So to obtain the total percentaje we just divide the read value by 256
+	 */
+	*response = data / 256;
+	return 0;
+}
+
+static int max17043_init(const struct device *dev)
+{
+	const struct max17043_config *cfg = dev->config;
+	uint16_t version;
+	int rc = max17043_read_register(dev, REGISTER_VERSION, &version);
+
+	if (!device_is_ready(cfg->i2c.bus)) {
+		LOG_ERR("Bus device is not ready");
+		return -ENODEV;
+	}
+
+	if (rc < 0) {
+		LOG_ERR("Cannot read from I2C");
+		return rc;
+	}
+
+	LOG_INF("MAX17043 version: %x", version);
+
+	return 0;
+}
+
+/**
+ * Get a single property from the fuel gauge
+ */
+int max17043_get_single_prop(const struct device *dev, fuel_gauge_prop_t prop,
+			     union fuel_gauge_prop_val *val)
+{
+	struct max17043_data *data = dev->data;
+	int rc = 0;
+
+	switch (prop) {
+	case FUEL_GAUGE_RELATIVE_STATE_OF_CHARGE:
+		rc = max17043_percent(dev, &data->charge);
+
+		if (rc < 0) {
+			return rc;
+		}
+
+		val->relative_state_of_charge = data->charge;
+		break;
+	case FUEL_GAUGE_VOLTAGE:
+		rc = max17043_voltage(dev, &data->voltage);
+		if (rc < 0) {
+			return rc;
+		}
+		val->voltage = data->voltage;
+		break;
+	default:
+		rc = -ENOTSUP;
+	}
+
+	return rc;
+}
+
+static const struct fuel_gauge_driver_api max17043_driver_api = {
+	.get_property = &max17043_get_single_prop,
+};
+
+#define MAX17043_DEFINE(inst)                                                                      \
+	static struct max17043_data max17043_data_##inst;                                          \
+                                                                                                   \
+	static const struct max17043_config max17043_config_##inst = {                             \
+		.i2c = I2C_DT_SPEC_INST_GET(inst)};                                                \
+                                                                                                   \
+	DEVICE_DT_INST_DEFINE(inst, &max17043_init, NULL, &max17043_data_##inst,                   \
+			      &max17043_config_##inst, POST_KERNEL,                                \
+			      CONFIG_FUEL_GAUGE_INIT_PRIORITY, &max17043_driver_api);
+
+DT_INST_FOREACH_STATUS_OKAY(MAX17043_DEFINE)

drivers/fuel_gauge/max17043/max17043.h

@@ -0,0 +1,24 @@
+/*
+ * Copyright (c) 2025 Mohammed Billoo <mab@mab-labs.com>
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#pragma once
+
+#include <zephyr/drivers/i2c.h>
+
+#define REGISTER_VCELL   0x02
+#define REGISTER_SOC     0x04
+#define REGISTER_MODE    0x06
+#define REGISTER_VERSION 0x08
+#define REGISTER_HIBRT   0x0A
+#define REGISTER_CONFIG  0x0C
+#define REGISTER_COMMAND 0xFE
+
+#define RESET_COMMAND   0x5400
+#define QUICKSTART_MODE 0x4000
+
+struct max17043_config {
+	struct i2c_dt_spec i2c;
+};

dts/bindings/fuel-gauge/maxim,max17043.yaml

@@ -0,0 +1,10 @@
+# Copyright (c) 2025 Mohammed Billoo <mab@mab-labs.com>
+# SPDX-License-Identifier: Apache-2.0
+
+description: |
+  Maxim MAX17043 Fuel Gauge with ModelGauge. See more info at:
+  https://www.analog.com/media/en/technical-documentation/data-sheets/max17043-max17044.pdf
+
+compatible: "maxim,max17043"
+
+include: [i2c-device.yaml, fuel-gauge.yaml]