drivers: sensor: STM32 die temperature driver

STM32 internal temperature sensor driver.
This sensor can be used to measure the temperature of the CPU
and its surroundings.

Signed-off-by: Eug Krashtan <eug.krashtan@gmail.com>

drivers/sensor/CMakeLists.txt

@@ -74,6 +74,7 @@ add_subdirectory_ifdef(CONFIG_SI7055		si7055)
 add_subdirectory_ifdef(CONFIG_SI7060		si7060)
 add_subdirectory_ifdef(CONFIG_SM351LT		sm351lt)
 add_subdirectory_ifdef(CONFIG_HAS_STMEMSC	stmemsc)
+add_subdirectory_ifdef(CONFIG_STM32_TEMP	stm32_temp)
 add_subdirectory_ifdef(CONFIG_STTS751		stts751)
 add_subdirectory_ifdef(CONFIG_SX9500		sx9500)
 add_subdirectory_ifdef(CONFIG_TH02		    th02)

drivers/sensor/Kconfig

@@ -186,6 +186,8 @@ source "drivers/sensor/si7060/Kconfig"
 
 source "drivers/sensor/sm351lt/Kconfig"
 
+source "drivers/sensor/stm32_temp/Kconfig"
+
 source "drivers/sensor/stts751/Kconfig"
 
 source "drivers/sensor/sx9500/Kconfig"

drivers/sensor/stm32_temp/CMakeLists.txt

@@ -0,0 +1,5 @@
+# SPDX-License-Identifier: Apache-2.0
+
+zephyr_library()
+
+zephyr_library_sources_ifdef(CONFIG_STM32_TEMP stm32_temp.c)

drivers/sensor/stm32_temp/Kconfig

@@ -0,0 +1,10 @@
+# STM32 temperature sensor configuration options
+
+# Copyright (c) 2021 Eug Krashtan
+# SPDX-License-Identifier: Apache-2.0
+
+config STM32_TEMP
+	bool "STM32 Temperature Sensor"
+	depends on (ADC && SOC_FAMILY_STM32)
+	help
+	  Enable driver for STM32 temperature sensor.

drivers/sensor/stm32_temp/stm32_temp.c

@@ -0,0 +1,144 @@
+/*
+ * Copyright (c) 2021 Eug Krashtan
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <device.h>
+#include <drivers/sensor.h>
+#include <drivers/adc.h>
+#include <logging/log.h>
+
+LOG_MODULE_REGISTER(stm32_temp, CONFIG_SENSOR_LOG_LEVEL);
+
+#define DT_DRV_COMPAT st_stm32_temp
+
+struct stm32_temp_data {
+	const struct device *adc;
+	uint8_t channel;
+	struct adc_channel_cfg adc_cfg;
+	struct adc_sequence adc_seq;
+	struct k_mutex mutex;
+	int16_t sample_buffer;
+	int32_t mv; /* Sensor value in millivolts */
+};
+
+struct stm32_temp_config {
+	int avgslope;
+	int v25_mv;
+	int tsv_mv;
+	bool is_ntc;
+};
+
+static int stm32_temp_sample_fetch(const struct device *dev,
+				  enum sensor_channel chan)
+{
+	const struct stm32_temp_config *cfg = dev->config;
+	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_read(data->adc, sp);
+	sp->calibrate = false;
+	if (rc == 0) {
+		data->mv = data->sample_buffer * cfg->tsv_mv /	0x0FFF;
+	}
+
+	k_mutex_unlock(&data->mutex);
+
+	return 0;
+}
+
+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 (cfg->is_ntc) {
+		temp = (float)(cfg->v25_mv - data->mv);
+	} else {
+		temp = (float)(data->mv - cfg->v25_mv);
+	}
+	temp = (temp/cfg->avgslope)*10;
+	temp += 25;
+	sensor_value_from_double(val, temp);
+
+	return 0;
+}
+
+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_channel_cfg *accp = &data->adc_cfg;
+	struct adc_sequence *asp = &data->adc_seq;
+	int rc;
+
+	k_mutex_init(&data->mutex);
+
+	if (!device_is_ready(data->adc)) {
+		LOG_ERR("Device %s is not ready", data->adc->name);
+		return -ENODEV;
+	}
+
+	*accp = (struct adc_channel_cfg){
+		.gain = ADC_GAIN_1,
+		.reference = ADC_REF_INTERNAL,
+		.acquisition_time = ADC_ACQ_TIME_MAX,
+		.channel_id = data->channel,
+		.differential = 0
+	};
+	rc = adc_channel_setup(data->adc, accp);
+	LOG_DBG("Setup AIN%u got %d", data->channel, rc);
+
+	*asp = (struct adc_sequence){
+		.channels = BIT(data->channel),
+		.buffer = &data->sample_buffer,
+		.buffer_size = sizeof(data->sample_buffer),
+		.resolution = 12,
+		.calibrate = true,
+	};
+
+	return 0;
+}
+
+#define STM32_TEMP_INST(idx)    \
+	static struct stm32_temp_data inst_##idx##_data = {  \
+		.adc = DEVICE_DT_GET(DT_IO_CHANNELS_CTLR(  \
+						DT_INST(idx, st_stm32_temp))), \
+		.channel = DT_IO_CHANNELS_INPUT( \
+						DT_INST(idx, st_stm32_temp)) \
+	};  \
+	static const struct stm32_temp_config inst_##idx##_config = { \
+		.avgslope = DT_INST_PROP(idx, avgslope),  \
+		.v25_mv = DT_INST_PROP(idx, v25),  \
+		.tsv_mv = DT_INST_PROP(idx, ts_voltage_mv),  \
+		.is_ntc = DT_INST_PROP(idx, ntc)  \
+	};  \
+	DEVICE_DT_INST_DEFINE(idx,  \
+		    stm32_temp_init,    \
+		    NULL,               \
+		    &inst_##idx##_data, \
+			&inst_##idx##_config,  \
+		    POST_KERNEL,           \
+		    CONFIG_SENSOR_INIT_PRIORITY, \
+		    &stm32_temp_driver_api);
+
+DT_INST_FOREACH_STATUS_OKAY(STM32_TEMP_INST)

dts/bindings/sensor/st,stm32-temp.yaml

@@ -0,0 +1,44 @@
+# Copyright (c) 2021, Eug Krashtan
+# SPDX-License-Identifier: Apache-2.0
+
+description: STM32 family TEMP node
+
+compatible: "st,stm32-temp"
+
+include: base.yaml
+
+properties:
+    label:
+      required: true
+
+    io-channels:
+      required: true
+      description: ADC channel for temperature sensor
+
+    ts-voltage-mv:
+      type: int
+      default: 3300
+      description: Temperature sensor voltage in millivolts
+
+    avgslope:
+      type: int
+      default: 25
+      description: >
+        Average slope of T-V chart (in mV/C x10) according to
+        datasheet "Electrical characteristics/Operating conditions"
+        STM32F1 Table 5.3.19 (min 4 mV/C, max 4.6, default 4.3)
+        STM32F4 Table 6.3.21 default 2.5
+
+    v25:
+      type: int
+      default: 760
+      description: >
+        Voltage of temperature sensor at 25C in mV according to
+        datasheet "Electrical characteristics/Operating conditions"
+        STM32F1 Table 5.3.19 (min 1340, max 1520, default 1430)
+        STM32F4 Table 6.3.21 default 760
+
+    ntc:
+      type: boolean
+      description: >
+        Negative Temperature Coefficient. True if STM32F1

tests/drivers/build_all/sensors_i_z.conf

@@ -37,6 +37,7 @@ CONFIG_SI7006=y
 CONFIG_SI7055=y
 CONFIG_SI7060=y
 CONFIG_SM351LT=y
+CONFIG_STM32_TEMP=y
 CONFIG_SX9500=y
 CONFIG_TACH_NPCX=y
 CONFIG_TEMP_NRF5=y