blinky/src/battery_module.c

#include <stdbool.h>
#include <stdint.h>

#include <app_event_manager.h>

#define MODULE battery_module
#include <caf/events/module_state_event.h>
#include <caf/events/power_event.h>

#include <zephyr/device.h>
#include <zephyr/devicetree.h>
#include <zephyr/drivers/sensor.h>
#include <zephyr/kernel.h>
#include <zephyr/logging/log.h>
#include <zephyr/pm/device.h>

LOG_MODULE_REGISTER(MODULE, LOG_LEVEL_INF);

#define VBATT_NODE DT_PATH(vbatt)
#define BATTERY_SAMPLE_INTERVAL K_SECONDS(1)

BUILD_ASSERT(DT_NODE_HAS_STATUS(VBATT_NODE, okay),
	     "Missing /vbatt voltage-divider node in devicetree");

static const struct device *const vbatt_dev = DEVICE_DT_GET(VBATT_NODE);
static struct k_work_delayable battery_sample_work;
static bool initialized;
static bool running;

static int sensor_value_to_mv(const struct sensor_value *value)
{
	return (value->val1 * 1000) + (value->val2 / 1000);
}

static int measurement_enable(bool enable)
{
	enum pm_device_action action = enable ? PM_DEVICE_ACTION_RESUME
					      : PM_DEVICE_ACTION_SUSPEND;
	int err = pm_device_action_run(vbatt_dev, action);

	if (err && (err != -EALREADY) && (err != -ENOTSUP)) {
		LOG_ERR("Cannot %s vbatt sensor (%d)", enable ? "resume" : "suspend", err);
		return err;
	}

	return 0;
}

static void battery_sample_fn(struct k_work *work)
{
	struct sensor_value voltage;
	int err;

	ARG_UNUSED(work);

	if (!running) {
		return;
	}

	err = sensor_sample_fetch(vbatt_dev);
	if (err) {
		LOG_WRN("Battery sample fetch failed (%d)", err);
		goto reschedule;
	}

	err = sensor_channel_get(vbatt_dev, SENSOR_CHAN_VOLTAGE, &voltage);
	if (err) {
		LOG_WRN("Battery channel get failed (%d)", err);
		goto reschedule;
	}

	LOG_INF("Battery voltage: %d mV", sensor_value_to_mv(&voltage));

reschedule:
	if (running) {
		k_work_reschedule(&battery_sample_work, BATTERY_SAMPLE_INTERVAL);
	}
}

static int module_init(void)
{
	if (!device_is_ready(vbatt_dev)) {
		LOG_ERR("vbatt device not ready");
		return -ENODEV;
	}

	k_work_init_delayable(&battery_sample_work, battery_sample_fn);

	return 0;
}

static int module_start(void)
{
	int err;

	if (running) {
		return 0;
	}

	err = measurement_enable(true);
	if (err) {
		return err;
	}

	running = true;
	k_work_reschedule(&battery_sample_work, K_NO_WAIT);

	return 0;
}

static void module_pause(void)
{
	if (!running) {
		return;
	}

	(void)k_work_cancel_delayable(&battery_sample_work);
	(void)measurement_enable(false);
	running = false;
}

static bool app_event_handler(const struct app_event_header *aeh)
{
	if (is_module_state_event(aeh)) {
		const struct module_state_event *event = cast_module_state_event(aeh);

		if (check_state(event, MODULE_ID(main), MODULE_STATE_READY)) {
			int err;

			if (!initialized) {
				err = module_init();
				if (err) {
					module_set_state(MODULE_STATE_ERROR);
					return false;
				}

				initialized = true;
			}

			err = module_start();
			if (err) {
				module_set_state(MODULE_STATE_ERROR);
			} else {
				module_set_state(MODULE_STATE_READY);
			}
		}

		return false;
	}

	if (is_power_down_event(aeh)) {
		if (initialized) {
			module_pause();
			module_set_state(MODULE_STATE_STANDBY);
		}

		return false;
	}

	if (is_wake_up_event(aeh)) {
		if (initialized) {
			int err = module_start();

			if (err) {
				module_set_state(MODULE_STATE_ERROR);
			} else {
				module_set_state(MODULE_STATE_READY);
			}
		}

		return false;
	}

	__ASSERT_NO_MSG(false);
	return false;
}

APP_EVENT_LISTENER(MODULE, app_event_handler);
APP_EVENT_SUBSCRIBE(MODULE, module_state_event);
APP_EVENT_SUBSCRIBE_EARLY(MODULE, power_down_event);
APP_EVENT_SUBSCRIBE(MODULE, wake_up_event);