[PATCH 1/6] iio: chemical: scd30: add core driver

[Tomasz Duszynski <tomasz.duszynski@octakon.com>]

Add Sensirion SCD30 carbon dioxide core driver.

Signed-off-by: Tomasz Duszynski <tomasz.duszynski@octakon.com>
---
 drivers/iio/chemical/Kconfig      |  11 +
 drivers/iio/chemical/Makefile     |   1 +
 drivers/iio/chemical/scd30.h      |  72 +++
 drivers/iio/chemical/scd30_core.c | 796 ++++++++++++++++++++++++++++++
 4 files changed, 880 insertions(+)
 create mode 100644 drivers/iio/chemical/scd30.h
 create mode 100644 drivers/iio/chemical/scd30_core.c

diff --git a/drivers/iio/chemical/Kconfig b/drivers/iio/chemical/Kconfig
index 0b91de4df8f4..55f249333fa2 100644
--- a/drivers/iio/chemical/Kconfig
+++ b/drivers/iio/chemical/Kconfig
@@ -74,6 +74,17 @@ 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
diff --git a/drivers/iio/chemical/Makefile b/drivers/iio/chemical/Makefile
index 33d3a595dda9..54abcb641262 100644
--- a/drivers/iio/chemical/Makefile
+++ b/drivers/iio/chemical/Makefile
@@ -11,6 +11,7 @@ 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
diff --git a/drivers/iio/chemical/scd30.h b/drivers/iio/chemical/scd30.h
new file mode 100644
index 000000000000..814782f5e71a
--- /dev/null
+++ b/drivers/iio/chemical/scd30.h
@@ -0,0 +1,72 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _SCD30_H
+#define _SCD30_H
+
+#include <linux/completion.h>
+#include <linux/device.h>
+#include <linux/i2c.h>
+#include <linux/mutex.h>
+#include <linux/pm.h>
+#include <linux/regulator/consumer.h>
+#include <linux/types.h>
+
+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
+
+struct scd30_state {
+	/* serialize access to the device */
+	struct mutex lock;
+	struct device *dev;
+	struct regulator *vdd;
+	struct completion meas_ready;
+	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];
+
+	int (*command)(struct scd30_state *state, enum scd30_cmd cmd, u16 arg,
+		       char *rsp, int size);
+};
+
+int scd30_suspend(struct device *dev);
+int scd30_resume(struct device *dev);
+
+static SIMPLE_DEV_PM_OPS(scd30_pm_ops, scd30_suspend, scd30_resume);
+
+int scd30_probe(struct device *dev, int irq, const char *name, void *priv,
+		int (*command)(struct scd30_state *state, enum scd30_cmd cmd,
+			       u16 arg, char *rsp, int size));
+
+#endif
diff --git a/drivers/iio/chemical/scd30_core.c b/drivers/iio/chemical/scd30_core.c
new file mode 100644
index 000000000000..4dc7e8f9a4f1
--- /dev/null
+++ b/drivers/iio/chemical/scd30_core.c
@@ -0,0 +1,796 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Sensirion SCD30 carbon dioxide sensor core driver
+ *
+ * Copyright (c) Tomasz Duszynski <tomasz.duszynski@octakon.com>
+ */
+#include <asm/byteorder.h>
+#include <linux/bits.h>
+#include <linux/compiler.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 "scd30.h"
+
+/* pressure compensation in millibars */
+#define SCD30_PRESSURE_COMP_MIN 700
+#define SCD30_PRESSURE_COMP_MAX 1400
+#define SCD30_PRESSURE_COMP_DEFAULT 1013
+/* measurement interval in seconds */
+#define SCD30_MEAS_INTERVAL_MIN 2
+#define SCD30_MEAS_INTERVAL_MAX 1800
+#define SCD30_MEAS_INTERVAL_DEFAULT SCD30_MEAS_INTERVAL_MIN
+/* reference CO2 concentration in ppm */
+#define SCD30_FRC_MIN 400
+#define SCD30_FRC_MAX 2000
+
+enum {
+	CONC,
+	TEMP,
+	HR,
+};
+
+static int scd30_command(struct scd30_state *state, enum scd30_cmd cmd, u16 arg,
+			 char *rsp, int size)
+{
+	int ret;
+
+	ret = state->command(state, cmd, arg, rsp, size);
+	if (ret)
+		return ret;
+
+	/*
+	 * assumption holds that response buffer pointer has been already
+	 * properly aligned so casts are safe
+	 */
+	while (size >= sizeof(u32)) {
+		*(u32 *)rsp = be32_to_cpup((__be32 *)rsp);
+		rsp += sizeof(u32);
+		size -= sizeof(u32);
+	}
+
+	if (size)
+		*(u16 *)rsp = be16_to_cpup((__be16 *)rsp);
+
+	return 0;
+}
+
+static int scd30_reset(struct scd30_state *state)
+{
+	int ret;
+	u16 val;
+
+	ret = scd30_command(state, CMD_RESET, 0, NULL, 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(state, CMD_MEAS_READY, 0, (char *)&val, sizeof(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 = scd30_command(state, CMD_READ_MEAS, 0, (char *)state->meas,
+			    sizeof(state->meas));
+	if (ret)
+		return ret;
+
+	for (i = 0; i < ARRAY_SIZE(state->meas); i++)
+		state->meas[i] = scd30_float_to_fp(state->meas[i]);
+
+	/*
+	 * Accuracy within calibrated operating range is
+	 * +-(30ppm + 3% measurement) so fractional part does
+	 * not add real value. Moreover, ppm is an integer.
+	 */
+	state->meas[CONC] /= 100;
+
+	return 0;
+}
+
+static int scd30_wait_meas_irq(struct scd30_state *state)
+{
+	int ret, timeout = msecs_to_jiffies(state->meas_interval * 1250);
+
+	reinit_completion(&state->meas_ready);
+	enable_irq(state->irq);
+	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 tries = 5;
+
+	while (tries--) {
+		int ret;
+		u16 val;
+
+		ret = scd30_command(state, CMD_MEAS_READY, 0, (char *)&val,
+				    sizeof(val));
+		if (ret)
+			return -EIO;
+
+		/* new measurement available */
+		if (val)
+			break;
+
+		msleep_interruptible(state->meas_interval * 250);
+	}
+
+	if (tries == -1)
+		return -ETIMEDOUT;
+
+	return 0;
+}
+
+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, meas[SCD30_MEAS_COUNT];
+
+	switch (mask) {
+	case IIO_CHAN_INFO_PROCESSED:
+		ret = iio_device_claim_direct_mode(indio_dev);
+		if (ret)
+			return ret;
+
+		mutex_lock(&state->lock);
+		ret = scd30_read(state);
+		memcpy(meas, state->meas, sizeof(meas));
+		mutex_unlock(&state->lock);
+		iio_device_release_direct_mode(indio_dev);
+		if (ret)
+			return ret;
+
+		switch (chan->type) {
+		case IIO_CONCENTRATION:
+			*val = meas[chan->address] / 10000;
+			*val2 = (meas[chan->address] % 10000) * 100;
+			return IIO_VAL_INT_PLUS_MICRO;
+		case IIO_TEMP:
+		case IIO_HUMIDITYRELATIVE:
+			*val = meas[chan->address] * 10;
+			return IIO_VAL_INT;
+		default:
+			return -EINVAL;
+		}
+	case IIO_CHAN_INFO_SCALE:
+		switch (chan->type) {
+		case IIO_CONCENTRATION:
+			*val = 0;
+			*val2 = 100;
+			return IIO_VAL_INT_PLUS_MICRO;
+		case IIO_TEMP:
+		case IIO_HUMIDITYRELATIVE:
+			*val = 10;
+			return IIO_VAL_INT;
+		default:
+			return -EINVAL;
+		}
+	}
+
+	return -EINVAL;
+}
+
+static ssize_t pressure_comp_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;
+
+	mutex_lock(&state->lock);
+	ret = sprintf(buf, "%d\n", state->pressure_comp);
+	mutex_unlock(&state->lock);
+
+	return ret;
+}
+
+static ssize_t pressure_comp_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;
+
+	if (kstrtou16(buf, 0, &val))
+		return -EINVAL;
+
+	if ((val < SCD30_PRESSURE_COMP_MIN) || (val > SCD30_PRESSURE_COMP_MAX))
+		return -EINVAL;
+
+	mutex_lock(&state->lock);
+	ret = scd30_command(state, CMD_START_MEAS, val, NULL, 0);
+	if (ret)
+		goto out;
+
+	state->pressure_comp = val;
+out:
+	mutex_unlock(&state->lock);
+
+	return ret ?: len;
+}
+
+static ssize_t pressure_comp_available_show(struct device *dev,
+					    struct device_attribute *attr,
+					    char *buf)
+{
+	return sprintf(buf, "[%d %d %d]\n", SCD30_PRESSURE_COMP_MIN, 1,
+		       SCD30_PRESSURE_COMP_MAX);
+}
+
+static ssize_t meas_interval_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(state, CMD_MEAS_INTERVAL, 0, (char *)&val,
+			    sizeof(val));
+	mutex_unlock(&state->lock);
+
+	return ret ?: sprintf(buf, "%d\n", val);
+}
+
+static ssize_t meas_interval_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;
+
+	if (kstrtou16(buf, 0, &val))
+		return -EINVAL;
+
+	if ((val < SCD30_MEAS_INTERVAL_MIN) || (val > SCD30_MEAS_INTERVAL_MAX))
+		return -EINVAL;
+
+	mutex_lock(&state->lock);
+	ret = scd30_command(state, CMD_MEAS_INTERVAL, val, NULL, 0);
+	if (ret)
+		goto out;
+
+	state->meas_interval = val;
+out:
+	mutex_unlock(&state->lock);
+
+	return ret ?: len;
+}
+
+static ssize_t meas_interval_available_show(struct device *dev,
+					    struct device_attribute *attr,
+					    char *buf)
+{
+	return sprintf(buf, "[%d %d %d]\n", SCD30_MEAS_INTERVAL_MIN, 1,
+		       SCD30_MEAS_INTERVAL_MAX);
+}
+
+static ssize_t asc_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(state, CMD_ASC, 0, (char *)&val, sizeof(val));
+	mutex_unlock(&state->lock);
+
+	return ret ?: sprintf(buf, "%d\n", val);
+}
+
+static ssize_t asc_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;
+
+	if (kstrtou16(buf, 0, &val))
+		return -EINVAL;
+
+	val = !!val;
+	mutex_lock(&state->lock);
+	ret = scd30_command(state, CMD_ASC, val, NULL, 0);
+	mutex_unlock(&state->lock);
+
+	return ret ?: len;
+}
+
+static ssize_t frc_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);
+	u16 val;
+	int ret;
+
+	mutex_lock(&state->lock);
+	ret = scd30_command(state, CMD_FRC, 0, (char *)&val, sizeof(val));
+	mutex_unlock(&state->lock);
+
+	return ret ?: sprintf(buf, "%d\n", val);
+}
+
+static ssize_t frc_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;
+
+	if (kstrtou16(buf, 0, &val))
+		return -EINVAL;
+
+	if ((val < SCD30_FRC_MIN) || (val > SCD30_FRC_MAX))
+		return -EINVAL;
+
+	mutex_lock(&state->lock);
+	ret = scd30_command(state, CMD_FRC, val, NULL, 0);
+	mutex_unlock(&state->lock);
+
+	return ret ?: len;
+}
+
+static ssize_t frc_available_show(struct device *dev,
+				  struct device_attribute *attr, char *buf)
+{
+	return sprintf(buf, "[%d %d %d]\n", SCD30_FRC_MIN, 1, SCD30_FRC_MAX);
+}
+
+static ssize_t temp_offset_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(state, CMD_TEMP_OFFSET, 0, (char *)&val,
+			    sizeof(val));
+	mutex_unlock(&state->lock);
+
+	return ret ?: sprintf(buf, "%d\n", val);
+}
+
+static ssize_t temp_offset_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;
+
+	if (kstrtou16(buf, 0, &val))
+		return -EINVAL;
+
+	/*
+	 * Manufacturer does not explicitly specify min/max sensible values
+	 * hence check is omitted for simplicity.
+	 */
+	mutex_lock(&state->lock);
+	ret = scd30_command(state, CMD_TEMP_OFFSET, val, NULL, 0);
+	mutex_unlock(&state->lock);
+
+	return ret ?: len;
+}
+
+static ssize_t reset_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;
+
+	mutex_lock(&state->lock);
+	/* after reset previous sensor state will be restored automatically */
+	ret = scd30_reset(state);
+	mutex_unlock(&state->lock);
+
+	return ret ?: len;
+}
+
+static IIO_DEVICE_ATTR_RW(pressure_comp, 0);
+static IIO_DEVICE_ATTR_RO(pressure_comp_available, 0);
+static IIO_DEVICE_ATTR_RW(meas_interval, 0);
+static IIO_DEVICE_ATTR_RO(meas_interval_available, 0);
+static IIO_DEVICE_ATTR_RW(asc, 0);
+static IIO_DEVICE_ATTR_RW(frc, 0);
+static IIO_DEVICE_ATTR_RO(frc_available, 0);
+static IIO_DEVICE_ATTR_RW(temp_offset, 0);
+static IIO_CONST_ATTR(temp_offset_available, "[0 1 65535]");
+static IIO_DEVICE_ATTR_WO(reset, 0);
+
+static struct attribute *scd30_attrs[] = {
+	&iio_dev_attr_pressure_comp.dev_attr.attr,
+	&iio_dev_attr_pressure_comp_available.dev_attr.attr,
+	&iio_dev_attr_meas_interval.dev_attr.attr,
+	&iio_dev_attr_meas_interval_available.dev_attr.attr,
+	&iio_dev_attr_asc.dev_attr.attr,
+	&iio_dev_attr_frc.dev_attr.attr,
+	&iio_dev_attr_frc_available.dev_attr.attr,
+	&iio_dev_attr_temp_offset.dev_attr.attr,
+	&iio_const_attr_temp_offset_available.dev_attr.attr,
+	&iio_dev_attr_reset.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,
+};
+
+#define SCD30_CHAN(_type, _index) \
+	.type = _type, \
+	.address = _index, \
+	.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED), \
+	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
+	.scan_index = _index
+
+#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[] = {
+	{
+		SCD30_CHAN(IIO_CONCENTRATION, CONC),
+		SCD30_CHAN_SCAN_TYPE('u', 16),
+	},
+	{
+		SCD30_CHAN(IIO_TEMP, TEMP),
+		SCD30_CHAN_SCAN_TYPE('s', 14),
+	},
+	{
+		SCD30_CHAN(IIO_HUMIDITYRELATIVE, HR),
+		SCD30_CHAN_SCAN_TYPE('u', 14),
+	},
+	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(state, CMD_STOP_MEAS, 0, NULL, 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(state, CMD_START_MEAS, state->pressure_comp,
+			     NULL, 0);
+}
+EXPORT_SYMBOL(scd30_resume);
+
+static void scd30_exit(void *data)
+{
+	struct scd30_state *state = data;
+
+	scd30_command(state, CMD_STOP_MEAS, 0, NULL, 0);
+	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);
+	/* co2 concentration, temperature, rh, padding, timestamp */
+	int data[SCD30_MEAS_COUNT + 1 + 2], ret = 0;
+
+	mutex_lock(&state->lock);
+	if (!iio_trigger_using_own(indio_dev))
+		ret = scd30_read_poll(state);
+	else
+		ret = scd30_read_meas(state);
+	memcpy(data, state->meas, sizeof(state->meas));
+	mutex_unlock(&state->lock);
+	if (ret)
+		goto out;
+
+	iio_push_to_buffers_with_timestamp(indio_dev, data,
+					   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,
+};
+
+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");
+
+	disable_irq(state->irq);
+
+	return ret;
+}
+
+int scd30_probe(struct device *dev, int irq, const char *name, void *priv,
+		int (*command)(struct scd30_state *state, enum scd30_cmd cmd,
+			       u16 arg, char *rsp, int size))
+{
+	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;
+
+	dev_set_drvdata(dev, indio_dev);
+
+	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);
+
+	indio_dev->dev.parent = 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)) {
+		dev_err(dev, "failed to get vdd regulator\n");
+		return PTR_ERR(state->vdd);
+	}
+
+	ret = regulator_enable(state->vdd);
+	if (ret) {
+		dev_err(dev, "failed to enable vdd regulator\n");
+		return ret;
+	}
+
+	ret = devm_add_action_or_reset(dev, scd30_exit, 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(state, CMD_FW_VERSION, 0, (char *)&val,
+			    sizeof(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(state, CMD_MEAS_INTERVAL, state->meas_interval,
+			    NULL, 0);
+	if (ret) {
+		dev_err(dev, "failed to set measurement interval: %d\n", ret);
+		return ret;
+	}
+
+	ret = scd30_command(state, CMD_START_MEAS, state->pressure_comp,
+			    NULL, 0);
+	if (ret) {
+		dev_err(dev, "failed to start measurement: %d\n", 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");
-- 
2.26.1