iio: chemical: scd30: add core driver

Add Sensirion SCD30 carbon dioxide core driver.
Signed-off-by: Tomasz Duszynski <tomasz.duszynski@octakon.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Documentation/ABI/testing/sysfs-bus-iio-scd30

+What:		/sys/bus/iio/devices/iio:deviceX/calibration_auto_enable
+Date:		June 2020
+KernelVersion:	5.8
+Contact:	linux-iio@vger.kernel.org
+Description:
+		Contaminants build-up in the measurement chamber or optical
+		elements deterioration leads to sensor drift.
+
+		One can compensate for sensor drift by using automatic self
+		calibration procedure (asc).
+
+		Writing 1 or 0 to this attribute will respectively activate or
+		deactivate asc.
+
+		Upon reading current asc status is returned.
+
+What:		/sys/bus/iio/devices/iio:deviceX/calibration_forced_value
+Date:		June 2020
+KernelVersion:	5.8
+Contact:	linux-iio@vger.kernel.org
+Description:
+		Contaminants build-up in the measurement chamber or optical
+		elements deterioration leads to sensor drift.
+
+		One can compensate for sensor drift by using forced
+		recalibration (frc). This is useful in case there's known
+		co2 reference available nearby the sensor.
+
+		Picking value from the range [400 1 2000] and writing it to the
+		sensor will set frc.
+
+		Upon reading current frc value is returned. Note that after
+		power cycling default value (i.e 400) is returned even though
+		internally sensor had recalibrated itself.

MAINTAINERS

@@ -15351,6 +15351,12 @@ S:	Maintained
 F:	drivers/misc/phantom.c
 F:	include/uapi/linux/phantom.h
 
+SENSIRION SCD30 CARBON DIOXIDE SENSOR DRIVER
+M:	Tomasz Duszynski <tomasz.duszynski@octakon.com>
+S:	Maintained
+F:	drivers/iio/chemical/scd30.h
+F:	drivers/iio/chemical/scd30_core.c
+
 SENSIRION SPS30 AIR POLLUTION SENSOR DRIVER
 M:	Tomasz Duszynski <tduszyns@gmail.com>
 S:	Maintained

drivers/iio/chemical/Kconfig

@@ -85,6 +85,17 @@ config PMS7003
 	  To compile this driver as a module, choose M here: the module will
 	  be called pms7003.
 
+config SCD30_CORE
+	tristate "SCD30 carbon dioxide sensor driver"
+	select IIO_BUFFER
+	select IIO_TRIGGERED_BUFFER
+	help
+	  Say Y here to build support for the Sensirion SCD30 sensor with carbon
+	  dioxide, relative humidity and temperature sensing capabilities.
+
+	  To compile this driver as a module, choose M here: the module will
+	  be called scd30_core.
+
 config SENSIRION_SGP30
 	tristate "Sensirion SGPxx gas sensors"
 	depends on I2C

drivers/iio/chemical/Makefile

@@ -12,6 +12,7 @@ obj-$(CONFIG_BME680_SPI) += bme680_spi.o
 obj-$(CONFIG_CCS811)		+= ccs811.o
 obj-$(CONFIG_IAQCORE)		+= ams-iaq-core.o
 obj-$(CONFIG_PMS7003) += pms7003.o
+obj-$(CONFIG_SCD30_CORE) += scd30_core.o
 obj-$(CONFIG_SENSIRION_SGP30)	+= sgp30.o
 obj-$(CONFIG_SPS30) += sps30.o
 obj-$(CONFIG_VZ89X)		+= vz89x.o

drivers/iio/chemical/scd30.h

+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _SCD30_H
+#define _SCD30_H
+
+#include <linux/completion.h>
+#include <linux/device.h>
+#include <linux/mutex.h>
+#include <linux/pm.h>
+#include <linux/regulator/consumer.h>
+#include <linux/types.h>
+
+struct scd30_state;
+
+enum scd30_cmd {
+	/* start continuous measurement with pressure compensation */
+	CMD_START_MEAS,
+	/* stop continuous measurement */
+	CMD_STOP_MEAS,
+	/* set/get measurement interval */
+	CMD_MEAS_INTERVAL,
+	/* check whether new measurement is ready */
+	CMD_MEAS_READY,
+	/* get measurement */
+	CMD_READ_MEAS,
+	/* turn on/off automatic self calibration */
+	CMD_ASC,
+	/* set/get forced recalibration value */
+	CMD_FRC,
+	/* set/get temperature offset */
+	CMD_TEMP_OFFSET,
+	/* get firmware version */
+	CMD_FW_VERSION,
+	/* reset sensor */
+	CMD_RESET,
+	/*
+	 * Command for altitude compensation was omitted intentionally because
+	 * the same can be achieved by means of CMD_START_MEAS which takes
+	 * pressure above the sea level as an argument.
+	 */
+};
+
+#define SCD30_MEAS_COUNT 3
+
+typedef int (*scd30_command_t)(struct scd30_state *state, enum scd30_cmd cmd, u16 arg,
+			       void *response, int size);
+
+struct scd30_state {
+	/* serialize access to the device */
+	struct mutex lock;
+	struct device *dev;
+	struct regulator *vdd;
+	struct completion meas_ready;
+	/*
+	 * priv pointer is solely for serdev driver private data. We keep it
+	 * here because driver_data inside dev has been already used for iio and
+	 * struct serdev_device doesn't have one.
+	 */
+	void *priv;
+	int irq;
+	/*
+	 * no way to retrieve current ambient pressure compensation value from
+	 * the sensor so keep one around
+	 */
+	u16 pressure_comp;
+	u16 meas_interval;
+	int meas[SCD30_MEAS_COUNT];
+
+	scd30_command_t command;
+};
+
+int scd30_suspend(struct device *dev);
+int scd30_resume(struct device *dev);
+
+static __maybe_unused SIMPLE_DEV_PM_OPS(scd30_pm_ops, scd30_suspend, scd30_resume);
+
+int scd30_probe(struct device *dev, int irq, const char *name, void *priv, scd30_command_t command);
+
+#endif

drivers/iio/chemical/scd30_core.c

+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Sensirion SCD30 carbon dioxide sensor core driver
+ *
+ * Copyright (c) 2020 Tomasz Duszynski <tomasz.duszynski@octakon.com>
+ */
+#include <linux/bits.h>
+#include <linux/completion.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/errno.h>
+#include <linux/export.h>
+#include <linux/iio/buffer.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+#include <linux/iio/trigger.h>
+#include <linux/iio/trigger_consumer.h>
+#include <linux/iio/triggered_buffer.h>
+#include <linux/iio/types.h>
+#include <linux/interrupt.h>
+#include <linux/irqreturn.h>
+#include <linux/jiffies.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/regulator/consumer.h>
+#include <linux/string.h>
+#include <linux/sysfs.h>
+#include <linux/types.h>
+#include <asm/byteorder.h>
+
+#include "scd30.h"
+
+#define SCD30_PRESSURE_COMP_MIN_MBAR 700
+#define SCD30_PRESSURE_COMP_MAX_MBAR 1400
+#define SCD30_PRESSURE_COMP_DEFAULT 1013
+#define SCD30_MEAS_INTERVAL_MIN_S 2
+#define SCD30_MEAS_INTERVAL_MAX_S 1800
+#define SCD30_MEAS_INTERVAL_DEFAULT SCD30_MEAS_INTERVAL_MIN_S
+#define SCD30_FRC_MIN_PPM 400
+#define SCD30_FRC_MAX_PPM 2000
+#define SCD30_TEMP_OFFSET_MAX 655360
+#define SCD30_EXTRA_TIMEOUT_PER_S 250
+
+enum {
+	SCD30_CONC,
+	SCD30_TEMP,
+	SCD30_HR,
+};
+
+static int scd30_command_write(struct scd30_state *state, enum scd30_cmd cmd, u16 arg)
+{
+	return state->command(state, cmd, arg, NULL, 0);
+}
+
+static int scd30_command_read(struct scd30_state *state, enum scd30_cmd cmd, u16 *val)
+{
+	__be16 tmp;
+	int ret;
+
+	ret = state->command(state, cmd, 0, &tmp, sizeof(tmp));
+	*val = be16_to_cpup(&tmp);
+
+	return ret;
+}
+
+static int scd30_reset(struct scd30_state *state)
+{
+	int ret;
+	u16 val;
+
+	ret = scd30_command_write(state, CMD_RESET, 0);
+	if (ret)
+		return ret;
+
+	/* sensor boots up within 2 secs */
+	msleep(2000);
+	/*
+	 * Power-on-reset causes sensor to produce some glitch on i2c bus and
+	 * some controllers end up in error state. Try to recover by placing
+	 * any data on the bus.
+	 */
+	scd30_command_read(state, CMD_MEAS_READY, &val);
+
+	return 0;
+}
+
+/* simplified float to fixed point conversion with a scaling factor of 0.01 */
+static int scd30_float_to_fp(int float32)
+{
+	int fraction, shift,
+	    mantissa = float32 & GENMASK(22, 0),
+	    sign = (float32 & BIT(31)) ? -1 : 1,
+	    exp = (float32 & ~BIT(31)) >> 23;
+
+	/* special case 0 */
+	if (!exp && !mantissa)
+		return 0;
+
+	exp -= 127;
+	if (exp < 0) {
+		exp = -exp;
+		/* return values ranging from 1 to 99 */
+		return sign * ((((BIT(23) + mantissa) * 100) >> 23) >> exp);
+	}
+
+	/* return values starting at 100 */
+	shift = 23 - exp;
+	float32 = BIT(exp) + (mantissa >> shift);
+	fraction = mantissa & GENMASK(shift - 1, 0);
+
+	return sign * (float32 * 100 + ((fraction * 100) >> shift));
+}
+
+static int scd30_read_meas(struct scd30_state *state)
+{
+	int i, ret;
+
+	ret = state->command(state, CMD_READ_MEAS, 0, state->meas, sizeof(state->meas));
+	if (ret)
+		return ret;
+
+	be32_to_cpu_array(state->meas, (__be32 *)state->meas, ARRAY_SIZE(state->meas));
+
+	for (i = 0; i < ARRAY_SIZE(state->meas); i++)
+		state->meas[i] = scd30_float_to_fp(state->meas[i]);
+
+	/*
+	 * co2 is left unprocessed while temperature and humidity are scaled
+	 * to milli deg C and milli percent respectively.
+	 */
+	state->meas[SCD30_TEMP] *= 10;
+	state->meas[SCD30_HR] *= 10;
+
+	return 0;
+}
+
+static int scd30_wait_meas_irq(struct scd30_state *state)
+{
+	int ret, timeout;
+
+	reinit_completion(&state->meas_ready);
+	enable_irq(state->irq);
+	timeout = msecs_to_jiffies(state->meas_interval * (1000 + SCD30_EXTRA_TIMEOUT_PER_S));
+	ret = wait_for_completion_interruptible_timeout(&state->meas_ready, timeout);
+	if (ret > 0)
+		ret = 0;
+	else if (!ret)
+		ret = -ETIMEDOUT;
+
+	disable_irq(state->irq);
+
+	return ret;
+}
+
+static int scd30_wait_meas_poll(struct scd30_state *state)
+{
+	int timeout = state->meas_interval * SCD30_EXTRA_TIMEOUT_PER_S, tries = 5;
+
+	do {
+		int ret;
+		u16 val;
+
+		ret = scd30_command_read(state, CMD_MEAS_READY, &val);
+		if (ret)
+			return -EIO;
+
+		/* new measurement available */
+		if (val)
+			break;
+
+		msleep_interruptible(timeout);
+	} while (--tries);
+
+	return tries ? 0 : -ETIMEDOUT;
+}
+
+static int scd30_read_poll(struct scd30_state *state)
+{
+	int ret;
+
+	ret = scd30_wait_meas_poll(state);
+	if (ret)
+		return ret;
+
+	return scd30_read_meas(state);
+}
+
+static int scd30_read(struct scd30_state *state)
+{
+	if (state->irq > 0)
+		return scd30_wait_meas_irq(state);
+
+	return scd30_read_poll(state);
+}
+
+static int scd30_read_raw(struct iio_dev *indio_dev, struct iio_chan_spec const *chan,
+			  int *val, int *val2, long mask)
+{
+	struct scd30_state *state = iio_priv(indio_dev);
+	int ret = -EINVAL;
+	u16 tmp;
+
+	mutex_lock(&state->lock);
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+	case IIO_CHAN_INFO_PROCESSED:
+		if (chan->output) {
+			*val = state->pressure_comp;
+			ret = IIO_VAL_INT;
+			break;
+		}
+
+		ret = iio_device_claim_direct_mode(indio_dev);
+		if (ret)
+			break;
+
+		ret = scd30_read(state);
+		if (ret) {
+			iio_device_release_direct_mode(indio_dev);
+			break;
+		}
+
+		*val = state->meas[chan->address];
+		iio_device_release_direct_mode(indio_dev);
+		ret = IIO_VAL_INT;
+		break;
+	case IIO_CHAN_INFO_SCALE:
+		*val = 0;
+		*val2 = 1;
+		ret = IIO_VAL_INT_PLUS_MICRO;
+		break;
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		ret = scd30_command_read(state, CMD_MEAS_INTERVAL, &tmp);
+		if (ret)
+			break;
+
+		*val = 0;
+		*val2 = 1000000000 / tmp;
+		ret = IIO_VAL_INT_PLUS_NANO;
+		break;
+	case IIO_CHAN_INFO_CALIBBIAS:
+		ret = scd30_command_read(state, CMD_TEMP_OFFSET, &tmp);
+		if (ret)
+			break;
+
+		*val = tmp;
+		ret = IIO_VAL_INT;
+		break;
+	}
+	mutex_unlock(&state->lock);
+
+	return ret;
+}
+
+static int scd30_write_raw(struct iio_dev *indio_dev, struct iio_chan_spec const *chan,
+			   int val, int val2, long mask)
+{
+	struct scd30_state *state = iio_priv(indio_dev);
+	int ret = -EINVAL;
+
+	mutex_lock(&state->lock);
+	switch (mask) {
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		if (val)
+			break;
+
+		val = 1000000000 / val2;
+		if (val < SCD30_MEAS_INTERVAL_MIN_S || val > SCD30_MEAS_INTERVAL_MAX_S)
+			break;
+
+		ret = scd30_command_write(state, CMD_MEAS_INTERVAL, val);
+		if (ret)
+			break;
+
+		state->meas_interval = val;
+		break;
+	case IIO_CHAN_INFO_RAW:
+		switch (chan->type) {
+		case IIO_PRESSURE:
+			if (val < SCD30_PRESSURE_COMP_MIN_MBAR ||
+			    val > SCD30_PRESSURE_COMP_MAX_MBAR)
+				break;
+
+			ret = scd30_command_write(state, CMD_START_MEAS, val);
+			if (ret)
+				break;
+
+			state->pressure_comp = val;
+			break;
+		default:
+			break;
+		}
+		break;
+	case IIO_CHAN_INFO_CALIBBIAS:
+		if (val < 0 || val > SCD30_TEMP_OFFSET_MAX)
+			break;
+		/*
+		 * Manufacturer does not explicitly specify min/max sensible
+		 * values hence check is omitted for simplicity.
+		 */
+		ret = scd30_command_write(state, CMD_TEMP_OFFSET / 10, val);
+	}
+	mutex_unlock(&state->lock);
+
+	return ret;
+}
+
+static int scd30_write_raw_get_fmt(struct iio_dev *indio_dev, struct iio_chan_spec const *chan,
+				   long mask)
+{
+	switch (mask) {
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		return IIO_VAL_INT_PLUS_NANO;
+	case IIO_CHAN_INFO_RAW:
+	case IIO_CHAN_INFO_CALIBBIAS:
+		return IIO_VAL_INT;
+	}
+
+	return -EINVAL;
+}
+
+static const int scd30_pressure_raw_available[] = {
+	SCD30_PRESSURE_COMP_MIN_MBAR, 1, SCD30_PRESSURE_COMP_MAX_MBAR,
+};
+
+static const int scd30_temp_calibbias_available[] = {
+	0, 10, SCD30_TEMP_OFFSET_MAX,
+};
+
+static int scd30_read_avail(struct iio_dev *indio_dev, struct iio_chan_spec const *chan,
+			    const int **vals, int *type, int *length, long mask)
+{
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		*vals = scd30_pressure_raw_available;
+		*type = IIO_VAL_INT;
+
+		return IIO_AVAIL_RANGE;
+	case IIO_CHAN_INFO_CALIBBIAS:
+		*vals = scd30_temp_calibbias_available;
+		*type = IIO_VAL_INT;
+
+		return IIO_AVAIL_RANGE;
+	}
+
+	return -EINVAL;
+}
+
+static ssize_t sampling_frequency_available_show(struct device *dev, struct device_attribute *attr,
+						 char *buf)
+{
+	int i = SCD30_MEAS_INTERVAL_MIN_S;
+	ssize_t len = 0;
+
+	do {
+		len += scnprintf(buf + len, PAGE_SIZE - len, "0.%09u ", 1000000000 / i);
+		/*
+		 * Not all values fit PAGE_SIZE buffer hence print every 6th
+		 * (each frequency differs by 6s in time domain from the
+		 * adjacent). Unlisted but valid ones are still accepted.
+		 */
+		i += 6;
+	} while (i <= SCD30_MEAS_INTERVAL_MAX_S);
+
+	buf[len - 1] = '\n';
+
+	return len;
+}
+
+static ssize_t calibration_auto_enable_show(struct device *dev, struct device_attribute *attr,
+					    char *buf)
+{
+	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
+	struct scd30_state *state = iio_priv(indio_dev);
+	int ret;
+	u16 val;
+
+	mutex_lock(&state->lock);
+	ret = scd30_command_read(state, CMD_ASC, &val);
+	mutex_unlock(&state->lock);
+
+	return ret ?: sprintf(buf, "%d\n", val);
+}
+
+static ssize_t calibration_auto_enable_store(struct device *dev, struct device_attribute *attr,
+					     const char *buf, size_t len)
+{
+	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
+	struct scd30_state *state = iio_priv(indio_dev);
+	bool val;
+	int ret;
+
+	ret = kstrtobool(buf, &val);
+	if (ret)
+		return ret;
+
+	mutex_lock(&state->lock);
+	ret = scd30_command_write(state, CMD_ASC, val);
+	mutex_unlock(&state->lock);
+
+	return ret ?: len;
+}
+
+static ssize_t calibration_forced_value_show(struct device *dev, struct device_attribute *attr,
+					     char *buf)
+{
+	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
+	struct scd30_state *state = iio_priv(indio_dev);
+	int ret;
+	u16 val;
+
+	mutex_lock(&state->lock);
+	ret = scd30_command_read(state, CMD_FRC, &val);
+	mutex_unlock(&state->lock);
+
+	return ret ?: sprintf(buf, "%d\n", val);
+}
+
+static ssize_t calibration_forced_value_store(struct device *dev, struct device_attribute *attr,
+					      const char *buf, size_t len)
+{
+	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
+	struct scd30_state *state = iio_priv(indio_dev);
+	int ret;
+	u16 val;
+
+	ret = kstrtou16(buf, 0, &val);
+	if (ret)
+		return ret;
+
+	if (val < SCD30_FRC_MIN_PPM || val > SCD30_FRC_MAX_PPM)
+		return -EINVAL;
+
+	mutex_lock(&state->lock);
+	ret = scd30_command_write(state, CMD_FRC, val);
+	mutex_unlock(&state->lock);
+
+	return ret ?: len;
+}
+
+static IIO_DEVICE_ATTR_RO(sampling_frequency_available, 0);
+static IIO_DEVICE_ATTR_RW(calibration_auto_enable, 0);
+static IIO_DEVICE_ATTR_RW(calibration_forced_value, 0);
+
+static struct attribute *scd30_attrs[] = {
+	&iio_dev_attr_sampling_frequency_available.dev_attr.attr,
+	&iio_dev_attr_calibration_auto_enable.dev_attr.attr,
+	&iio_dev_attr_calibration_forced_value.dev_attr.attr,
+	NULL
+};
+
+static const struct attribute_group scd30_attr_group = {
+	.attrs = scd30_attrs,
+};
+
+static const struct iio_info scd30_info = {
+	.attrs = &scd30_attr_group,
+	.read_raw = scd30_read_raw,
+	.write_raw = scd30_write_raw,
+	.write_raw_get_fmt = scd30_write_raw_get_fmt,
+	.read_avail = scd30_read_avail,
+};
+
+#define SCD30_CHAN_SCAN_TYPE(_sign, _realbits) .scan_type = { \
+	.sign = _sign, \
+	.realbits = _realbits, \
+	.storagebits = 32, \
+	.endianness = IIO_CPU, \
+}
+
+static const struct iio_chan_spec scd30_channels[] = {
+	{
+		/*
+		 * this channel is special in a sense we are pretending that
+		 * sensor is able to change measurement chamber pressure but in
+		 * fact we're just setting pressure compensation value
+		 */
+		.type = IIO_PRESSURE,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+		.info_mask_separate_available = BIT(IIO_CHAN_INFO_RAW),
+		.output = 1,
+		.scan_index = -1,
+	},
+	{
+		.type = IIO_CONCENTRATION,
+		.channel2 = IIO_MOD_CO2,
+		.address = SCD30_CONC,
+		.scan_index = SCD30_CONC,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+				      BIT(IIO_CHAN_INFO_SCALE),
+		.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ),
+		.modified = 1,
+
+		SCD30_CHAN_SCAN_TYPE('u', 20),
+	},
+	{
+		.type = IIO_TEMP,
+		.address = SCD30_TEMP,
+		.scan_index = SCD30_TEMP,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED) |
+				      BIT(IIO_CHAN_INFO_CALIBBIAS),
+		.info_mask_separate_available = BIT(IIO_CHAN_INFO_CALIBBIAS),
+		.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ),
+
+		SCD30_CHAN_SCAN_TYPE('s', 18),
+	},
+	{
+		.type = IIO_HUMIDITYRELATIVE,
+		.address = SCD30_HR,
+		.scan_index = SCD30_HR,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
+		.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ),
+
+		SCD30_CHAN_SCAN_TYPE('u', 17),
+	},
+	IIO_CHAN_SOFT_TIMESTAMP(3),
+};
+
+int __maybe_unused scd30_suspend(struct device *dev)
+{
+	struct iio_dev *indio_dev = dev_get_drvdata(dev);
+	struct scd30_state *state  = iio_priv(indio_dev);
+	int ret;
+
+	ret = scd30_command_write(state, CMD_STOP_MEAS, 0);
+	if (ret)
+		return ret;
+
+	return regulator_disable(state->vdd);
+}
+EXPORT_SYMBOL(scd30_suspend);
+
+int __maybe_unused scd30_resume(struct device *dev)
+{
+	struct iio_dev *indio_dev = dev_get_drvdata(dev);
+	struct scd30_state *state = iio_priv(indio_dev);
+	int ret;
+
+	ret = regulator_enable(state->vdd);
+	if (ret)
+		return ret;
+
+	return scd30_command_write(state, CMD_START_MEAS, state->pressure_comp);
+}
+EXPORT_SYMBOL(scd30_resume);
+
+static void scd30_stop_meas(void *data)
+{
+	struct scd30_state *state = data;
+
+	scd30_command_write(state, CMD_STOP_MEAS, 0);
+}
+
+static void scd30_disable_regulator(void *data)
+{
+	struct scd30_state *state = data;
+
+	regulator_disable(state->vdd);
+}
+
+static irqreturn_t scd30_irq_handler(int irq, void *priv)
+{
+	struct iio_dev *indio_dev = priv;
+
+	if (iio_buffer_enabled(indio_dev)) {
+		iio_trigger_poll(indio_dev->trig);
+
+		return IRQ_HANDLED;
+	}
+
+	return IRQ_WAKE_THREAD;
+}
+
+static irqreturn_t scd30_irq_thread_handler(int irq, void *priv)
+{
+	struct iio_dev *indio_dev = priv;
+	struct scd30_state *state = iio_priv(indio_dev);
+	int ret;
+
+	ret = scd30_read_meas(state);
+	if (ret)
+		goto out;
+
+	complete_all(&state->meas_ready);
+out:
+	return IRQ_HANDLED;
+}
+
+static irqreturn_t scd30_trigger_handler(int irq, void *p)
+{
+	struct iio_poll_func *pf = p;
+	struct iio_dev *indio_dev = pf->indio_dev;
+	struct scd30_state *state = iio_priv(indio_dev);
+	struct {
+		int data[SCD30_MEAS_COUNT];
+		s64 ts __aligned(8);
+	} scan;
+	int ret;
+
+	mutex_lock(&state->lock);
+	if (!iio_trigger_using_own(indio_dev))
+		ret = scd30_read_poll(state);
+	else
+		ret = scd30_read_meas(state);
+	memset(&scan, 0, sizeof(scan));
+	memcpy(scan.data, state->meas, sizeof(state->meas));
+	mutex_unlock(&state->lock);
+	if (ret)
+		goto out;
+
+	iio_push_to_buffers_with_timestamp(indio_dev, &scan, iio_get_time_ns(indio_dev));
+out:
+	iio_trigger_notify_done(indio_dev->trig);
+	return IRQ_HANDLED;
+}
+
+static int scd30_set_trigger_state(struct iio_trigger *trig, bool state)
+{
+	struct iio_dev *indio_dev = iio_trigger_get_drvdata(trig);
+	struct scd30_state *st = iio_priv(indio_dev);
+
+	if (state)
+		enable_irq(st->irq);
+	else
+		disable_irq(st->irq);
+
+	return 0;
+}
+
+static const struct iio_trigger_ops scd30_trigger_ops = {
+	.set_trigger_state = scd30_set_trigger_state,
+	.validate_device = iio_trigger_validate_own_device,
+};
+
+static int scd30_setup_trigger(struct iio_dev *indio_dev)
+{
+	struct scd30_state *state = iio_priv(indio_dev);
+	struct device *dev = indio_dev->dev.parent;
+	struct iio_trigger *trig;
+	int ret;
+
+	trig = devm_iio_trigger_alloc(dev, "%s-dev%d", indio_dev->name, indio_dev->id);
+	if (!trig) {
+		dev_err(dev, "failed to allocate trigger\n");
+		return -ENOMEM;
+	}
+
+	trig->dev.parent = dev;
+	trig->ops = &scd30_trigger_ops;
+	iio_trigger_set_drvdata(trig, indio_dev);
+
+	ret = devm_iio_trigger_register(dev, trig);
+	if (ret)
+		return ret;
+
+	indio_dev->trig = iio_trigger_get(trig);
+
+	ret = devm_request_threaded_irq(dev, state->irq, scd30_irq_handler,
+					scd30_irq_thread_handler, IRQF_TRIGGER_HIGH | IRQF_ONESHOT,
+					indio_dev->name, indio_dev);
+	if (ret)
+		dev_err(dev, "failed to request irq\n");
+
+	/*
+	 * Interrupt is enabled just before taking a fresh measurement
+	 * and disabled afterwards. This means we need to disable it here
+	 * to keep calls to enable/disable balanced.
+	 */
+	disable_irq(state->irq);
+
+	return ret;
+}
+
+int scd30_probe(struct device *dev, int irq, const char *name, void *priv,
+		scd30_command_t command)
+{
+	static const unsigned long scd30_scan_masks[] = { 0x07, 0x00 };
+	struct scd30_state *state;
+	struct iio_dev *indio_dev;
+	int ret;
+	u16 val;
+
+	indio_dev = devm_iio_device_alloc(dev, sizeof(*state));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	state = iio_priv(indio_dev);
+	state->dev = dev;
+	state->priv = priv;
+	state->irq = irq;
+	state->pressure_comp = SCD30_PRESSURE_COMP_DEFAULT;
+	state->meas_interval = SCD30_MEAS_INTERVAL_DEFAULT;
+	state->command = command;
+	mutex_init(&state->lock);
+	init_completion(&state->meas_ready);
+
+	dev_set_drvdata(dev, indio_dev);
+
+	indio_dev->info = &scd30_info;
+	indio_dev->name = name;
+	indio_dev->channels = scd30_channels;
+	indio_dev->num_channels = ARRAY_SIZE(scd30_channels);
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->available_scan_masks = scd30_scan_masks;
+
+	state->vdd = devm_regulator_get(dev, "vdd");
+	if (IS_ERR(state->vdd)) {
+		if (PTR_ERR(state->vdd) == -EPROBE_DEFER)
+			return -EPROBE_DEFER;
+
+		dev_err(dev, "failed to get regulator\n");
+		return PTR_ERR(state->vdd);
+	}
+
+	ret = regulator_enable(state->vdd);
+	if (ret)
+		return ret;
+
+	ret = devm_add_action_or_reset(dev, scd30_disable_regulator, state);
+	if (ret)
+		return ret;
+
+	ret = scd30_reset(state);
+	if (ret) {
+		dev_err(dev, "failed to reset device: %d\n", ret);
+		return ret;
+	}
+
+	if (state->irq > 0) {
+		ret = scd30_setup_trigger(indio_dev);
+		if (ret) {
+			dev_err(dev, "failed to setup trigger: %d\n", ret);
+			return ret;
+		}
+	}
+
+	ret = devm_iio_triggered_buffer_setup(dev, indio_dev, NULL, scd30_trigger_handler, NULL);
+	if (ret)
+		return ret;
+
+	ret = scd30_command_read(state, CMD_FW_VERSION, &val);
+	if (ret) {
+		dev_err(dev, "failed to read firmware version: %d\n", ret);
+		return ret;
+	}
+	dev_info(dev, "firmware version: %d.%d\n", val >> 8, (char)val);
+
+	ret = scd30_command_write(state, CMD_MEAS_INTERVAL, state->meas_interval);
+	if (ret) {
+		dev_err(dev, "failed to set measurement interval: %d\n", ret);
+		return ret;
+	}
+
+	ret = scd30_command_write(state, CMD_START_MEAS, state->pressure_comp);
+	if (ret) {
+		dev_err(dev, "failed to start measurement: %d\n", ret);
+		return ret;
+	}
+
+	ret = devm_add_action_or_reset(dev, scd30_stop_meas, state);
+	if (ret)
+		return ret;
+
+	return devm_iio_device_register(dev, indio_dev);
+}
+EXPORT_SYMBOL(scd30_probe);
+
+MODULE_AUTHOR("Tomasz Duszynski <tomasz.duszynski@octakon.com>");
+MODULE_DESCRIPTION("Sensirion SCD30 carbon dioxide sensor core driver");
+MODULE_LICENSE("GPL v2");