drivers: sensor: STS4x Add driver

This adds support for Sensirion's STS4x temperature sensor.

Signed-off-by: Jan Faeh <jan.faeh@sensirion.com>

drivers/sensor/sensirion/CMakeLists.txt

@@ -6,4 +6,5 @@ add_subdirectory_ifdef(CONFIG_SGP40 sgp40)
 add_subdirectory_ifdef(CONFIG_SHT3XD sht3xd)
 add_subdirectory_ifdef(CONFIG_SHT4X sht4x)
 add_subdirectory_ifdef(CONFIG_SHTCX shtcx)
+add_subdirectory_ifdef(CONFIG_STS4X sts4x)
 # zephyr-keep-sorted-stop

drivers/sensor/sensirion/Kconfig

@@ -6,4 +6,5 @@ source "drivers/sensor/sensirion/sgp40/Kconfig"
 source "drivers/sensor/sensirion/sht3xd/Kconfig"
 source "drivers/sensor/sensirion/sht4x/Kconfig"
 source "drivers/sensor/sensirion/shtcx/Kconfig"
+source "drivers/sensor/sensirion/sts4x/Kconfig"
 # zephyr-keep-sorted-stop

drivers/sensor/sensirion/sts4x/CMakeLists.txt

@@ -0,0 +1,5 @@
+# SPDX-License-Identifier: Apache-2.0
+
+zephyr_library()
+
+zephyr_library_sources(sts4x.c)

drivers/sensor/sensirion/sts4x/Kconfig

@@ -0,0 +1,13 @@
+# Drivers configuration options for Sensirion STS4x
+
+# Copyright (c) 2024 Jan Fäh
+# SPDX-License-Identifier: Apache-2.0
+
+config STS4X
+	bool "STS4x Temperature Sensor"
+	default y
+	depends on DT_HAS_SENSIRION_STS4X_ENABLED
+	select I2C
+	select CRC
+	help
+	  Enable driver for the Sensirion STS4x temperature sensors.

drivers/sensor/sensirion/sts4x/sts4x.c

@@ -0,0 +1,168 @@
+/*
+ * Copyright (c) 2024 Jan Fäh
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#define DT_DRV_COMPAT sensirion_sts4x
+
+#include <zephyr/device.h>
+#include <zephyr/kernel.h>
+#include <zephyr/drivers/sensor.h>
+#include <zephyr/drivers/i2c.h>
+#include <zephyr/logging/log.h>
+#include <zephyr/sys/__assert.h>
+#include <zephyr/sys/byteorder.h>
+#include <zephyr/sys/crc.h>
+#include <zephyr/devicetree.h>
+
+LOG_MODULE_REGISTER(STS4X, CONFIG_SENSOR_LOG_LEVEL);
+
+#define STS4X_CMD_RESET 0x94
+
+#define STS4X_RESET_TIME 1
+
+#define STS4X_CRC_POLY 0x31
+#define STS4X_CRC_INIT 0xFF
+
+#define STS4X_MAX_TEMP 175
+#define STS4X_MIN_TEMP -45
+
+struct sts4x_config {
+	struct i2c_dt_spec bus;
+	uint8_t repeatability;
+};
+
+struct sts4x_data {
+	uint16_t temp_sample;
+};
+
+static const uint8_t measure_cmds[3] = {0xE0, 0xF6, 0xFD};
+static const uint16_t measure_time_us[3] = {1600, 4500, 8300};
+
+static int sts4x_crc_check(uint16_t value, uint8_t sensor_crc)
+{
+	uint8_t buf[2];
+
+	sys_put_be16(value, buf);
+
+	uint8_t calculated_crc = crc8(buf, 2, STS4X_CRC_POLY, STS4X_CRC_INIT, false);
+
+	if (calculated_crc == sensor_crc) {
+		return 0;
+	}
+
+	return -EIO;
+}
+
+static int sts4x_write_command(const struct device *dev, uint8_t cmd)
+{
+	const struct sts4x_config *cfg = dev->config;
+	uint8_t tx_buf = cmd;
+
+	return i2c_write_dt(&cfg->bus, &tx_buf, 1);
+}
+
+static int sts4x_read_sample(const struct device *dev, uint16_t *temp_sample)
+{
+	const struct sts4x_config *cfg = dev->config;
+	uint8_t rx_buf[3];
+	int ret;
+
+	ret = i2c_read_dt(&cfg->bus, rx_buf, sizeof(rx_buf));
+	if (ret < 0) {
+		LOG_ERR("Failed to read data.");
+		return ret;
+	}
+
+	*temp_sample = sys_get_be16(rx_buf);
+	ret = sts4x_crc_check(*temp_sample, rx_buf[2]);
+	if (ret < 0) {
+		LOG_ERR("Invalid CRC.");
+		return ret;
+	}
+
+	return 0;
+}
+
+static int sts4x_sample_fetch(const struct device *dev, enum sensor_channel chan)
+{
+	struct sts4x_data *data = dev->data;
+	const struct sts4x_config *cfg = dev->config;
+	int ret;
+
+	if (chan == SENSOR_CHAN_ALL || chan == SENSOR_CHAN_AMBIENT_TEMP) {
+		ret = sts4x_write_command(dev, measure_cmds[cfg->repeatability]);
+		if (ret < 0) {
+			LOG_ERR("Failed to write measure command.");
+			return ret;
+		}
+
+		k_usleep(measure_time_us[cfg->repeatability]);
+
+		ret = sts4x_read_sample(dev, &data->temp_sample);
+		if (ret < 0) {
+			LOG_ERR("Failed to get temperature data.");
+			return ret;
+		}
+
+		return 0;
+	} else {
+		return -ENOTSUP;
+	}
+}
+
+static int sts4x_channel_get(const struct device *dev, enum sensor_channel chan,
+			     struct sensor_value *val)
+{
+	const struct sts4x_data *data = dev->data;
+
+	if (chan == SENSOR_CHAN_AMBIENT_TEMP) {
+		int64_t temp;
+
+		temp = data->temp_sample * STS4X_MAX_TEMP;
+		val->val1 = (int32_t)(temp / 0xFFFF) + STS4X_MIN_TEMP;
+		val->val2 = ((temp % 0xFFFF) * 1000000) / 0xFFFF;
+	} else {
+		return -ENOTSUP;
+	}
+	return 0;
+}
+
+static int sts4x_init(const struct device *dev)
+{
+	const struct sts4x_config *cfg = dev->config;
+	int ret;
+
+	if (!i2c_is_ready_dt(&cfg->bus)) {
+		LOG_ERR("Device not ready.");
+		return -ENODEV;
+	}
+
+	ret = sts4x_write_command(dev, STS4X_CMD_RESET);
+	if (ret < 0) {
+		LOG_ERR("Failed to reset the device.");
+		return ret;
+	}
+
+	k_msleep(STS4X_RESET_TIME);
+
+	return 0;
+}
+
+static const struct sensor_driver_api sts4x_api_funcs = {
+	.sample_fetch = sts4x_sample_fetch,
+	.channel_get = sts4x_channel_get,
+};
+
+#define STS4X_INIT(inst)                                                                           \
+	static struct sts4x_data sts4x_data_##inst;                                                \
+	static const struct sts4x_config sts4x_config_##inst = {                                   \
+		.bus = I2C_DT_SPEC_INST_GET(inst),                                                 \
+		.repeatability = DT_INST_PROP(inst, repeatability),                                \
+	};                                                                                         \
+	SENSOR_DEVICE_DT_INST_DEFINE(inst, sts4x_init, NULL, &sts4x_data_##inst,                   \
+				     &sts4x_config_##inst, POST_KERNEL,                            \
+				     CONFIG_SENSOR_INIT_PRIORITY, &sts4x_api_funcs);
+
+DT_INST_FOREACH_STATUS_OKAY(STS4X_INIT)

dts/bindings/sensor/sensirion,sts4x.yaml

@@ -0,0 +1,22 @@
+# Copyright (c) 2024, Jan Fäh
+# SPDX-License-Identifier: Apache-2.0
+
+description: Sensirion STS4x temperature sensor
+
+compatible: "sensirion,sts4x"
+
+include: [sensor-device.yaml, i2c-device.yaml]
+
+properties:
+  repeatability:
+    type: int
+    required: true
+    description: |
+      Repeatability of the T Measurement
+      0 = low -> 1.6 ms
+      1 = med -> 4.5 ms
+      2 = high -> 8.3 ms
+    enum:
+      - 0
+      - 1
+      - 2

tests/drivers/build_all/sensor/i2c.dtsi

@@ -1125,3 +1125,9 @@ test_i2c_ilps22qs: ilps22qs@9c {
 	avg = <LPS2xDF_DT_AVG_128_SAMPLES>;
 	fs = <ILPS22QS_DT_FS_MODE_1_1260>;
 };
+
+test_i2c_sts4x: sts4x@9d {
+	compatible = "sensirion,sts4x";
+	reg = <0x99>;
+	repeatability = <2>;
+};