fuel_gauge: composite: more flexible data sourcing

JordanYates · JordanYates · commit ad56be565e0c · 2025-04-10T12:29:44.000+10:00
Instead of explicitly specifying the source for the voltage and current
channels, specify primary and secondary data sources. If the requested
sensor channel does not exist on the primary source, the secondary
source will be tried.

Signed-off-by: Jordan Yates &lt;jordan@embeint.com&gt;
diff --git a/boards/nordic/thingy53/thingy53_nrf5340_common.dtsi b/boards/nordic/thingy53/thingy53_nrf5340_common.dtsi
@@ -95,7 +95,7 @@
 
 	fuel_gauge: fuel_gauge {
 		compatible = "zephyr,fuel-gauge-composite";
-		battery-voltage = <&vbatt>;
+		source-primary = <&vbatt>;
 		device-chemistry = "lithium-ion-polymer";
 		ocv-capacity-table-0 = <BATTERY_OCV_CURVE_LITHIUM_ION_POLYMER_DEFAULT>;
 		charge-full-design-microamp-hours = <1350000>;
diff --git a/drivers/fuel_gauge/composite/fuel_gauge_composite.c b/drivers/fuel_gauge/composite/fuel_gauge_composite.c
@@ -14,8 +14,8 @@
 #include <zephyr/kernel.h>
 
 struct composite_config {
-	const struct device *battery_voltage;
-	const struct device *battery_current;
+	const struct device *source_primary;
+	const struct device *source_secondary;
 	int32_t ocv_lookup_table[BATTERY_OCV_TABLE_LEN];
 	uint32_t charge_capacity_microamp_hours;
 	enum battery_chemistry chemistry;
@@ -40,6 +40,19 @@ static int composite_fetch(const struct device *dev)
 	return pm_device_runtime_put(dev);
 }
 
+static int composite_channel_get(const struct device *dev, enum sensor_channel chan,
+				 struct sensor_value *val)
+{
+	const struct composite_config *config = dev->config;
+	int rc;
+
+	rc = sensor_channel_get(config->source_primary, chan, val);
+	if ((rc == -ENOTSUP) && config->source_secondary) {
+		rc = sensor_channel_get(config->source_secondary, chan, val);
+	}
+	return rc;
+}
+
 static int composite_get_prop(const struct device *dev, fuel_gauge_prop_t prop,
 			      union fuel_gauge_prop_val *val)
 {
@@ -61,9 +74,9 @@ static int composite_get_prop(const struct device *dev, fuel_gauge_prop_t prop,
 
 	if (now >= data->next_reading) {
 		/* Trigger a sample on the input devices */
-		rc = composite_fetch(config->battery_voltage);
-		if ((rc == 0) && config->battery_current) {
-			rc = composite_fetch(config->battery_current);
+		rc = composite_fetch(config->source_primary);
+		if ((rc == 0) && config->source_secondary) {
+			rc = composite_fetch(config->source_secondary);
 		}
 		if (rc != 0) {
 			return rc;
@@ -87,7 +100,7 @@ static int composite_get_prop(const struct device *dev, fuel_gauge_prop_t prop,
 		val->full_charge_capacity = config->charge_capacity_microamp_hours / 1000;
 		break;
 	case FUEL_GAUGE_VOLTAGE:
-		rc = sensor_channel_get(config->battery_voltage, SENSOR_CHAN_VOLTAGE, &sensor_val);
+		rc = composite_channel_get(dev, SENSOR_CHAN_VOLTAGE, &sensor_val);
 		val->voltage = sensor_value_to_micro(&sensor_val);
 		break;
 	case FUEL_GAUGE_ABSOLUTE_STATE_OF_CHARGE:
@@ -96,7 +109,7 @@ static int composite_get_prop(const struct device *dev, fuel_gauge_prop_t prop,
 			return -ENOTSUP;
 		}
 		/* Fetch the voltage from the sensor */
-		rc = sensor_channel_get(config->battery_voltage, SENSOR_CHAN_VOLTAGE, &sensor_val);
+		rc = composite_channel_get(dev, SENSOR_CHAN_VOLTAGE, &sensor_val);
 		voltage = sensor_value_to_micro(&sensor_val);
 		if (rc == 0) {
 			/* Convert voltage to state of charge */
@@ -106,10 +119,7 @@ static int composite_get_prop(const struct device *dev, fuel_gauge_prop_t prop,
 		break;
 	case FUEL_GAUGE_CURRENT:
 	case FUEL_GAUGE_AVG_CURRENT:
-		if (config->battery_current == NULL) {
-			return -ENOTSUP;
-		}
-		rc = sensor_channel_get(config->battery_current, SENSOR_CHAN_CURRENT, &sensor_val);
+		rc = composite_channel_get(dev, SENSOR_CHAN_CURRENT, &sensor_val);
 		val->current = sensor_value_to_micro(&sensor_val);
 		break;
 	default:
@@ -119,22 +129,36 @@ static int composite_get_prop(const struct device *dev, fuel_gauge_prop_t prop,
 	return rc;
 }
 
+static int fuel_gauge_composite_init(const struct device *dev)
+{
+	const struct composite_config *config = dev->config;
+
+	/* Validate sources are ready */
+	if (!device_is_ready(config->source_primary)) {
+		return -ENODEV;
+	}
+	if (config->source_secondary && !!device_is_ready(config->source_secondary)) {
+		return -ENODEV;
+	}
+	return 0;
+}
+
 static DEVICE_API(fuel_gauge, composite_api) = {
 	.get_property = composite_get_prop,
 };
 
 #define COMPOSITE_INIT(inst)                                                                       \
 	static const struct composite_config composite_##inst##_config = {                         \
-		.battery_voltage = DEVICE_DT_GET(DT_INST_PROP(inst, battery_voltage)),             \
-		.battery_current = DEVICE_DT_GET_OR_NULL(DT_INST_PROP(inst, battery_current)),     \
+		.source_primary = DEVICE_DT_GET(DT_INST_PROP(inst, source_primary)),               \
+		.source_secondary = DEVICE_DT_GET_OR_NULL(DT_INST_PROP(inst, source_secondary)),   \
 		.ocv_lookup_table =                                                                \
 			BATTERY_OCV_TABLE_DT_GET(DT_DRV_INST(inst), ocv_capacity_table_0),         \
 		.charge_capacity_microamp_hours =                                                  \
 			DT_INST_PROP_OR(inst, charge_full_design_microamp_hours, 0),               \
 		.chemistry = BATTERY_CHEMISTRY_DT_GET(inst),                                       \
 	};                                                                                         \
 	static struct composite_data composite_##inst##_data;                                      \
-	DEVICE_DT_INST_DEFINE(inst, NULL, NULL, &composite_##inst##_data,                          \
+	DEVICE_DT_INST_DEFINE(inst, fuel_gauge_composite_init, NULL, &composite_##inst##_data,     \
 			      &composite_##inst##_config, POST_KERNEL,                             \
 			      CONFIG_SENSOR_INIT_PRIORITY, &composite_api);
 
diff --git a/dts/bindings/fuel-gauge/zephyr,fuel-gauge-composite.yaml b/dts/bindings/fuel-gauge/zephyr,fuel-gauge-composite.yaml
@@ -2,29 +2,28 @@
 # SPDX-License-Identifier: Apache-2.0
 
 description: |
-  Composite fuel-gauge constructed from analog input values
+  Composite fuel-gauge constructed from sensor devices
 
 compatible: "zephyr,fuel-gauge-composite"
 
 include: [fuel-gauge.yaml, battery.yaml]
 
 properties:
-  battery-voltage:
+  source-primary:
     type: phandle
     required: true
     description: |
-      Device to read battery voltage from.
+      Primary device to read sensor data from.
+      Device must implement the sensor API.
 
-      Device must implement the sensor API and provide the
-      `SENSOR_CHAN_VOLTAGE` channel.
-
-  battery-current:
+  source-secondary:
     type: phandle
     description: |
-      Device to read battery current from.
+      Secondary device to read sensor data from.
+      This device will be used if input-primary does not expose
+      a channel.
 
-      Device must implement the sensor API and provide the
-      `SENSOR_CHAN_CURRENT` channel.
+      Device must implement the sensor API.
 
   device-chemistry:
     required: true
diff --git a/tests/drivers/build_all/fuel_gauge/app.overlay b/tests/drivers/build_all/fuel_gauge/app.overlay
@@ -56,7 +56,7 @@
 		test_fuel_gauge: fuel_gauge {
 			compatible = "zephyr,fuel-gauge-composite";
 			status = "okay";
-			battery-voltage = <&test_vbatt>;
+			source-primary = <&test_vbatt>;
 			device-chemistry = "lithium-ion-polymer";
 			ocv-capacity-table-0 = <0>;
 			charge-full-design-microamp-hours = <1350000>;
diff --git a/tests/drivers/build_all/sensor/adc.dtsi b/tests/drivers/build_all/sensor/adc.dtsi
@@ -39,8 +39,8 @@ test_current: current_amp {
 test_composite_fuel_gauge: composite_fuel_gauge {
 	compatible = "zephyr,fuel-gauge-composite";
 	status = "okay";
-	battery-voltage = <&test_voltage>;
-	battery-current = <&test_current>;
+	source-primary = <&test_voltage>;
+	source-secondary = <&test_current>;
 	device-chemistry = "lithium-ion-polymer";
 	ocv-capacity-table-0 = <BATTERY_OCV_CURVE_LITHIUM_ION_POLYMER_DEFAULT>;
 	charge-full-design-microamp-hours = <1000000>;
