drivers: sensor: adxl345: add device PM support

Add support for the Zephyr device power management framework to
enable runtime power control of the ADXL345 accelerometer.

This implementation adds a pm_device_action callback that handles
SUSPEND and RESUME actions. When suspended, the sensor enters
standby mode for low power operation. On resume, it returns to
measurement mode.

The implementation follows the standard pattern used by other
sensor drivers (lis2dh, bme280, vcnl4040) and integrates with
the PM_DEVICE_DT_INST_DEFINE macro for automatic PM setup.

Tested on nRF52832 with CONFIG_PM_DEVICE enabled.

Signed-off-by: Tobias Kässer <t.kaesser@gmail.com>

Author: kaessert

drivers/sensor/adi/adxl345/adxl345.c

@@ -11,6 +11,7 @@
 #include <zephyr/drivers/gpio.h>
 #include <zephyr/drivers/i2c.h>
 #include <zephyr/logging/log.h>
+#include <zephyr/pm/device.h>
 #include <zephyr/sys/__assert.h>
 
 #include "adxl345.h"
@@ -472,6 +473,9 @@ static int adxl345_init(const struct device *dev)
 		return -EIO;
 	}
 
+	/* Initialize op_mode to reflect current state */
+	data->op_mode = ADXL345_MEASURE;
+
 #ifdef CONFIG_ADXL345_TRIGGER
 	rc = adxl345_init_interrupt(dev);
 	if (rc < 0) {
@@ -500,6 +504,34 @@ static int adxl345_init(const struct device *dev)
 	return 0;
 }
 
+#ifdef CONFIG_PM_DEVICE
+static int adxl345_pm_action(const struct device *dev,
+			     enum pm_device_action action)
+{
+	struct adxl345_dev_data *data = dev->data;
+	int rc;
+
+	switch (action) {
+	case PM_DEVICE_ACTION_RESUME:
+		/* Resume to measurement mode */
+		rc = adxl345_set_op_mode(dev, ADXL345_MEASURE);
+		if (rc == 0) {
+			data->op_mode = ADXL345_MEASURE;
+		}
+		return rc;
+	case PM_DEVICE_ACTION_SUSPEND:
+		/* Enter standby mode for low power */
+		rc = adxl345_set_op_mode(dev, ADXL345_STANDBY);
+		if (rc == 0) {
+			data->op_mode = ADXL345_STANDBY;
+		}
+		return rc;
+	default:
+		return -ENOTSUP;
+	}
+}
+#endif /* CONFIG_PM_DEVICE */
+
 #ifdef CONFIG_ADXL345_TRIGGER
 
 #define ADXL345_CFG_IRQ(inst)									   \
@@ -604,7 +636,8 @@ static int adxl345_init(const struct device *dev)
 		COND_CODE_1(DT_INST_ON_BUS(inst, spi), (ADXL345_CONFIG_SPI(inst)),		   \
 			    (ADXL345_CONFIG_I2C(inst)));					   \
 												   \
-	SENSOR_DEVICE_DT_INST_DEFINE(inst, adxl345_init, NULL,					   \
+	PM_DEVICE_DT_INST_DEFINE(inst, adxl345_pm_action);					   \
+	SENSOR_DEVICE_DT_INST_DEFINE(inst, adxl345_init, PM_DEVICE_DT_INST_GET(inst),		   \
 			      &adxl345_data_##inst, &adxl345_config_##inst, POST_KERNEL,	   \
 			      CONFIG_SENSOR_INIT_PRIORITY, &adxl345_api_funcs);
 

drivers/sensor/adi/adxl345/adxl345.h

@@ -170,6 +170,7 @@ struct adxl345_dev_data {
 	uint8_t is_full_res;
 	uint8_t selected_range;
 	enum adxl345_odr odr;
+	enum adxl345_op_mode op_mode;
 #ifdef CONFIG_ADXL345_TRIGGER
 	struct gpio_callback gpio_cb;