Untested basic SCD30 driver

boards/xtensa/minico2/minico2-pinctrl.dtsi

@@ -17,7 +17,7 @@
 	i2c0_default: i2c0_default {
 		group1 {
 			pinmux = <I2C0_SDA_GPIO32>,
-				 <I2C0_SDA_GPIO33>;
+				 <I2C0_SCL_GPIO33>;
 			bias-pull-up;
 			drive-open-drain;
 			output-high;

drivers/sensor/scd30/scd30.c

@@ -0,0 +1,176 @@
+#define DT_DRV_COMPAT sensirion_scd30
+
+#include <zephyr/device.h>
+#include <zephyr/drivers/i2c.h>
+#include <zephyr/drivers/sensor.h>
+#include <zephyr/kernel.h>
+#include <zephyr/logging/log.h>
+#include <zephyr/sys/byteorder.h>
+#include <zephyr/sys/crc.h>
+
+#include "scd30.h"
+
+LOG_MODULE_REGISTER(SCD30, CONFIG_SENSOR_LOG_LEVEL);
+
+/*
+ * Checksum used when recieving data. Used on several
+ * Sensirion devices, including SCD30
+ */
+static uint8_t scd30_compute_checksum(uint16_t value)
+{
+	uint8_t buf[2];
+	sys_put_be16(value, buf);
+	return crc8(buf, 2, 0x31, 0xff, false);
+}
+
+/*
+ * Check if the Sensirion checksum recieved is valid
+ * Takes a pointer to an array and uses 3 bytes
+ */
+static bool scd30_verify_checksum(uint8_t *buf)
+{
+	return crc8(buf, 2, 0x31, 0xff, false) == buf[2];
+}
+
+/*
+ * Extract a float from a measurement response buffer
+ * Takes a pointer to an array and uses 6 bytes
+ */
+static float scd30_extract_float(uint8_t *buf)
+{
+	uint32_t upper = sys_get_be16(buf);
+	uint32_t lower = sys_get_be16(&buf[3]);
+	uint32_t full = upper << 16 | lower;
+	return *((float *)&full);
+}
+
+static int scd30_write(const struct device *dev, uint16_t cmd, uint16_t data, bool has_data)
+{
+	const struct scd30_config *config = dev->config;
+	uint8_t tx_buf[5];
+
+	sys_put_be16(cmd, tx_buf);
+	if (has_data) {
+		sys_put_be16(data, &tx_buf[2]);
+		tx_buf[4] = scd30_compute_checksum(data);
+	}
+
+	return i2c_write_dt(&config->bus, tx_buf, has_data ? 5 : 2);
+}
+
+static int scd30_read(const struct device *dev, uint16_t cmd, uint8_t *buf, size_t buf_size)
+{
+	const struct scd30_config *config = dev->config;
+
+	if (scd30_write(dev, cmd, 0, false) < 0) {
+		LOG_ERR("Unable to write command while reading!");
+		return -EIO;
+	}
+
+	k_sleep(SCD30_READ_DELAY);
+
+	if (i2c_read_dt(&config->bus, buf, buf_size) < 0) {
+		LOG_ERR("Unable to read data!");
+		return -EIO;
+	}
+
+	for (size_t i = 0; i * 3 < buf_size - 2; i++) {
+		if (!scd30_verify_checksum(&buf[i * 3])) {
+			LOG_ERR("Recieved invalid CRC!");
+			return -EIO;
+		}
+	}
+
+	return 0;
+}
+
+static int scd30_sample_fetch(const struct device *dev, enum sensor_channel chan)
+{
+	struct scd30_data *data = dev->data;
+
+	__ASSERT_NO_MSG(chan == SENSOR_CHAN_ALL);
+	uint8_t rx_buf[18];
+
+	// Make sure there's a sample ready for us and clear the ready flag
+	if (scd30_read(dev, SCD30_CMD_CHECK_DATA_READY, rx_buf, 3) < 0) {
+		LOG_ERR("Unable to check if measurement is ready!");
+		return -EIO;
+	}
+
+	// Now actually read
+	if (scd30_read(dev, SCD30_CMD_READ_MEASUREMENT, rx_buf, 18) < 0) {
+		LOG_ERR("Unable to read measurement!");
+		return -EIO;
+	}
+
+	data->co2_sample = scd30_extract_float(rx_buf);
+	data->t_sample = scd30_extract_float(&rx_buf[6]);
+	data->rh_sample = scd30_extract_float(&rx_buf[12]);
+
+	return 0;
+}
+
+static int scd30_channel_get(const struct device *dev, enum sensor_channel chan,
+			     struct sensor_value *val)
+{
+	struct scd30_data *data = dev->data;
+	switch (chan) {
+	case SENSOR_CHAN_CO2:
+		return sensor_value_from_float(val, data->co2_sample);
+	case SENSOR_CHAN_AMBIENT_TEMP:
+		return sensor_value_from_float(val, data->t_sample);
+	case SENSOR_CHAN_HUMIDITY:
+		return sensor_value_from_float(val, data->rh_sample);
+	default:
+		return -ENOTSUP;
+	}
+}
+
+static const struct sensor_driver_api scd30_driver_api = {
+	.sample_fetch = scd30_sample_fetch,
+	.channel_get = scd30_channel_get,
+};
+
+static int scd30_init(const struct device *dev)
+{
+	const struct scd30_config *cfg = dev->config;
+
+	if (!device_is_ready(cfg->bus.bus)) {
+		LOG_ERR("I2C bus %s is not ready!", cfg->bus.bus->name);
+		return -EINVAL;
+	}
+
+	if (cfg->sampling_interval != 0) {
+		if (scd30_write(dev, SCD30_CMD_INTERVAL, cfg->sampling_interval, true) < 0) {
+			LOG_ERR("Failed to set SCD30 sampling interval!");
+			return -EIO;
+		}
+	}
+
+	if (cfg->asc_enabled < 2) {
+		if (scd30_write(dev, SCD30_CMD_ASC, cfg->asc_enabled, true) < 0) {
+			LOG_ERR("Failed to set SCD30 ASC!");
+			return -EIO;
+		}
+	}
+
+	if (scd30_write(dev, SCD30_CMD_START, 0, 1) < 0) {
+		LOG_ERR("Could not start SCD30!");
+		return -EIO;
+	}
+
+	return 0;
+};
+
+#define SCD30_DEFINE(inst)                                                                         \
+	struct scd30_data scd30_data_##inst;                                                       \
+	static const struct scd30_config scd30_cfg_##inst = {                                      \
+		.bus = I2C_DT_SPEC_INST_GET(inst),                                                 \
+		.asc_enabled = DT_INST_PROP_OR(inst, asc_enabled, 2),                              \
+		.sampling_interval = DT_INST_PROP_OR(inst, sampling_interval, 0),                  \
+		.rdy_gpio = GPIO_DT_SPEC_INST_GET_OR(inst, int_gpios, {0})};                       \
+	SENSOR_DEVICE_DT_INST_DEFINE(inst, scd30_init, NULL, &scd30_data_##inst,                   \
+				     &scd30_cfg_##inst, POST_KERNEL, CONFIG_SENSOR_INIT_PRIORITY,  \
+				     &scd30_driver_api);
+
+DT_INST_FOREACH_STATUS_OKAY(SCD30_DEFINE)

drivers/sensor/scd30/scd30.h

@@ -0,0 +1,30 @@
+#pragma once
+
+#include <zephyr/drivers/i2c.h>
+#include <zephyr/drivers/gpio.h>
+
+#define SCD30_READ_DELAY K_MSEC(3)
+
+#define SCD30_CMD_START            0x0010
+#define SCD30_CMD_STOP             0x0104
+#define SCD30_CMD_INTERVAL         0x4600
+#define SCD30_CMD_CHECK_DATA_READY 0x0202
+#define SCD30_CMD_READ_MEASUREMENT 0x0300
+#define SCD30_CMD_ASC              0x5306
+#define SCD30_CMD_SET_TEMP_OFFSET  0x5403
+#define SCD30_CMD_SET_ALTITUDE     0x5102
+#define SCD30_CMD_READ_VERSION     0xd100
+#define SCD30_CMD_SOFT_RESET       0xd304
+
+struct scd30_config {
+	struct i2c_dt_spec bus;
+	struct gpio_dt_spec rdy_gpio;
+	uint8_t asc_enabled;
+	uint16_t sampling_interval;
+};
+
+struct scd30_data {
+	float t_sample;
+	float rh_sample;
+	float co2_sample;
+};

dts/bindings/sensirion,scd30.yaml

@@ -1,3 +1,18 @@
 description: Sensirion SCD30 CO2, humidity, and temperature sensor
 compatible: "sensirion,scd30"
 include: [sensor-device.yaml, i2c-device.yaml]
+properties:
+  int-gpios:
+    type: phandle-array
+    description: |
+      GPIO pin connected to the SCD30 RDY pin. Without this async reads are unavailable
+  asc-enabled:
+    type: boolean
+    description: |
+      Enable automatic self calibration. If this property is not set then the value in the SCD30's
+      nonvolatile storage will be used.
+  sampling-interval:
+    type: int
+    description: |
+      How often to sample at bootup. If this property is not set then the value in the SCD30's
+      nonvolatile storage will be used.