drivers/sensor/stm32_temp/stm32_temp.c

/*
 * Copyright (c) 2021 Eug Krashtan
 * Copyright (c) 2022 Wouter Cappelle
 *
 * SPDX-License-Identifier: Apache-2.0
 */

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

LOG_MODULE_REGISTER(stm32_temp, CONFIG_SENSOR_LOG_LEVEL);
#define CAL_RES 12
#if DT_HAS_COMPAT_STATUS_OKAY(st_stm32_temp)
#define DT_DRV_COMPAT st_stm32_temp
#define HAS_CALIBRATION 0
#elif DT_HAS_COMPAT_STATUS_OKAY(st_stm32_temp_cal)
#define DT_DRV_COMPAT st_stm32_temp_cal
#define HAS_CALIBRATION 1
#else
#error "No compatible devicetree node found"
#endif

struct stm32_temp_data {
	const struct device *adc;
	const struct adc_channel_cfg adc_cfg;
	struct adc_sequence adc_seq;
	struct k_mutex mutex;
	int16_t sample_buffer;
	int16_t raw; /* raw adc Sensor value */
};

struct stm32_temp_config {
#if HAS_CALIBRATION
	uint16_t *cal1_addr;
	uint16_t *cal2_addr;
	int cal1_temp;
	int cal2_temp;
	int cal_vrefanalog;
	int ts_cal_shift;
#else
	int avgslope;
	int v25_mv;
	bool is_ntc;
#endif
};

static int stm32_temp_sample_fetch(const struct device *dev, enum sensor_channel chan)
{
	struct stm32_temp_data *data = dev->data;
	struct adc_sequence *sp = &data->adc_seq;
	int rc;

	if (chan != SENSOR_CHAN_ALL && chan != SENSOR_CHAN_DIE_TEMP) {
		return -ENOTSUP;
	}

	k_mutex_lock(&data->mutex, K_FOREVER);

	rc = adc_channel_setup(data->adc, &data->adc_cfg);
	if (rc) {
		LOG_DBG("Setup AIN%u got %d", data->adc_cfg.channel_id, rc);
		goto unlock;
	}

	rc = adc_read(data->adc, sp);
	if (rc == 0) {
		data->raw = data->sample_buffer;
	}

unlock:
	k_mutex_unlock(&data->mutex);

	return rc;
}

static int stm32_temp_channel_get(const struct device *dev, enum sensor_channel chan,
				  struct sensor_value *val)
{
	struct stm32_temp_data *data = dev->data;
	const struct stm32_temp_config *cfg = dev->config;
	float temp;

	if (chan != SENSOR_CHAN_DIE_TEMP) {
		return -ENOTSUP;
	}

#if HAS_CALIBRATION
	temp = ((float)data->raw * adc_ref_internal(data->adc)) / cfg->cal_vrefanalog;
	temp -= (*cfg->cal1_addr >> cfg->ts_cal_shift);
	temp *= (cfg->cal2_temp - cfg->cal1_temp);
	temp /= ((*cfg->cal2_addr - *cfg->cal1_addr) >> cfg->ts_cal_shift);
	temp += cfg->cal1_temp;
#else
	/* Sensor value in millivolts */
	int32_t mv = data->raw * adc_ref_internal(data->adc) / 0x0FFF;

	if (cfg->is_ntc) {
		temp = (float)(cfg->v25_mv - mv);
	} else {
		temp = (float)(mv - cfg->v25_mv);
	}
	temp = (temp / cfg->avgslope) * 10;
	temp += 25;
#endif

	return sensor_value_from_double(val, temp);
}

static const struct sensor_driver_api stm32_temp_driver_api = {
	.sample_fetch = stm32_temp_sample_fetch,
	.channel_get = stm32_temp_channel_get,
};

static int stm32_temp_init(const struct device *dev)
{
	struct stm32_temp_data *data = dev->data;
	struct adc_sequence *asp = &data->adc_seq;

	k_mutex_init(&data->mutex);

	if (!device_is_ready(data->adc)) {
		LOG_ERR("Device %s is not ready", data->adc->name);
		return -ENODEV;
	}

	*asp = (struct adc_sequence){
		.channels = BIT(data->adc_cfg.channel_id),
		.buffer = &data->sample_buffer,
		.buffer_size = sizeof(data->sample_buffer),
		.resolution = 12U,
	};

	return 0;
}


#define STM32_TEMP_DEFINE(inst)									\
	static struct stm32_temp_data stm32_temp_dev_data_##inst = {				\
		.adc = DEVICE_DT_GET(DT_INST_IO_CHANNELS_CTLR(inst)),				\
		.adc_cfg = {									\
			.gain = ADC_GAIN_1,							\
			.reference = ADC_REF_INTERNAL,						\
			.acquisition_time = ADC_ACQ_TIME_MAX,					\
			.channel_id = DT_INST_IO_CHANNELS_INPUT(inst),				\
			.differential = 0							\
		},										\
	};											\
												\
	static const struct stm32_temp_config stm32_temp_dev_config_##inst = {			\
		COND_CODE_1(HAS_CALIBRATION,							\
			    (.cal1_addr = (uint16_t *)DT_INST_PROP(inst, ts_cal1_addr),		\
			     .cal2_addr = (uint16_t *)DT_INST_PROP(inst, ts_cal2_addr),		\
			     .cal1_temp = DT_INST_PROP(inst, ts_cal1_temp),			\
			     .cal2_temp = DT_INST_PROP(inst, ts_cal2_temp),			\
			     .ts_cal_shift = (DT_INST_PROP(inst, ts_cal_resolution) - CAL_RES),	\
			     .cal_vrefanalog = DT_INST_PROP(inst, ts_cal_vrefanalog),),		\
			    (.avgslope = DT_INST_PROP(inst, avgslope),				\
			     .v25_mv = DT_INST_PROP(inst, v25),					\
			     .is_ntc = DT_INST_PROP(inst, ntc)))				\
	};											\
												\
	DEVICE_DT_INST_DEFINE(inst, stm32_temp_init, NULL,					\
			      &stm32_temp_dev_data_##inst, &stm32_temp_dev_config_##inst,	\
			      POST_KERNEL, CONFIG_SENSOR_INIT_PRIORITY,				\
			      &stm32_temp_driver_api);						\

DT_INST_FOREACH_STATUS_OKAY(STM32_TEMP_DEFINE)