[PATCH v3 0/4] Add support for SCD30 sensor

[PATCH v3 0/4] Add support for SCD30 sensor

[Tomasz Duszynski]

Following series adds support for Sensirion SCD30 sensor module capable of
measuring carbon dioxide, temperature and relative humidity. CO2 measurements
base on NDIR principle while temperature and relative humidity are measured by
the on board SHT31. As for sensor communication, both I2C and serial interfaces
are supported.

v3:
* simplify code by scaling temperature & humidity in _read_meas()
* update realbits in scan types
* s/adjecent/adjacent
* drop IIO_CHAN_INFO_RAW from _write_raw_get_fmt because there's no raw
  output channel
* rework locking in _read_raw
* fix endianess problem on BE machine
* align timestamp properly before pushing to buffers
* explain why interrupt gets disabled after registration
* add trigger validation
* drop SCALE for temperature and humidity channel as they are processed
* register action which stops measuring after starting measurements
* spit generic calibration attr into two doing specific things
* add comment explaining why priv in struct scd30_state is for
* rename node in binding example to co2-sensor

v2:
* move asm/byteorder.h towards the bottom of include list
* make channel address names in enum more specific
* add postfixes to defines and extra comments
* drop unneeded i2c include from scd30 header
* break generic command sending function into specialized options
* expose automatic calibration and forced calibration via the same attr
* use SAMP_FREQ to set frequency instead of meas_interval attr
* use CALISCALE to set pressure compensation instead of pressure_comp attr
* use CALIBBIAS to set temperature offset instead of temp_offset attr
* fix order in MAINTAINERS
* drop attribute allowing one to reset sensor
* as we have dt probing drop board file based probing (i2c_device_id)
* merge patches touching related files
* use fwnode API to retrieve interrupt from dt
* fix interrupt-parent spelling
* change binding license
* drop supply from required property

Tomasz Duszynski (4):
  iio: chemical: scd30: add core driver
  iio: chemical: scd30: add I2C interface driver
  iio: chemical: scd30: add serial interface driver
  dt-bindings: iio: scd30: add device binding file

 Documentation/ABI/testing/sysfs-bus-iio-scd30 |  34 +
 .../iio/chemical/sensirion,scd30.yaml         |  68 ++
 MAINTAINERS                                   |   9 +
 drivers/iio/chemical/Kconfig                  |  33 +
 drivers/iio/chemical/Makefile                 |   3 +
 drivers/iio/chemical/scd30.h                  |  80 ++
 drivers/iio/chemical/scd30_core.c             | 783 ++++++++++++++++++
 drivers/iio/chemical/scd30_i2c.c              | 134 +++
 drivers/iio/chemical/scd30_serial.c           | 266 ++++++
 9 files changed, 1410 insertions(+)
 create mode 100644 Documentation/ABI/testing/sysfs-bus-iio-scd30
 create mode 100644 Documentation/devicetree/bindings/iio/chemical/sensirion,scd30.yaml
 create mode 100644 drivers/iio/chemical/scd30.h
 create mode 100644 drivers/iio/chemical/scd30_core.c
 create mode 100644 drivers/iio/chemical/scd30_i2c.c
 create mode 100644 drivers/iio/chemical/scd30_serial.c

--
2.26.2

[PATCH v3 1/4] iio: chemical: scd30: add core driver

[Tomasz Duszynski]

Add Sensirion SCD30 carbon dioxide core driver.

Signed-off-by: Tomasz Duszynski <tomasz.duszynski@octakon.com>
---
 Documentation/ABI/testing/sysfs-bus-iio-scd30 |  34 +
 MAINTAINERS                                   |   6 +
 drivers/iio/chemical/Kconfig                  |  11 +
 drivers/iio/chemical/Makefile                 |   1 +
 drivers/iio/chemical/scd30.h                  |  80 ++
 drivers/iio/chemical/scd30_core.c             | 783 ++++++++++++++++++
 6 files changed, 915 insertions(+)
 create mode 100644 Documentation/ABI/testing/sysfs-bus-iio-scd30
 create mode 100644 drivers/iio/chemical/scd30.h
 create mode 100644 drivers/iio/chemical/scd30_core.c

diff --git a/Documentation/ABI/testing/sysfs-bus-iio-scd30 b/Documentation/ABI/testing/sysfs-bus-iio-scd30
new file mode 100644
index 000000000000..b9712f390bec
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-bus-iio-scd30
@@ -0,0 +1,34 @@
+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.
diff --git a/MAINTAINERS b/MAINTAINERS
index 60ed2963efaa..41a509cca6f1 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -15137,6 +15137,12 @@ 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
diff --git a/drivers/iio/chemical/Kconfig b/drivers/iio/chemical/Kconfig
index 7f21afd73b1c..99e852b67e55 100644
--- a/drivers/iio/chemical/Kconfig
+++ b/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
diff --git a/drivers/iio/chemical/Makefile b/drivers/iio/chemical/Makefile
index aba4167db745..c9804b041ecd 100644
--- a/drivers/iio/chemical/Makefile
+++ b/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
diff --git a/drivers/iio/chemical/scd30.h b/drivers/iio/chemical/scd30.h
new file mode 100644
index 000000000000..38dcf5647d7f
--- /dev/null
+++ b/drivers/iio/chemical/scd30.h
@@ -0,0 +1,80 @@
+/* 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
diff --git a/drivers/iio/chemical/scd30_core.c b/drivers/iio/chemical/scd30_core.c
new file mode 100644
index 000000000000..a41a09e7a513
--- /dev/null
+++ b/drivers/iio/chemical/scd30_core.c
@@ -0,0 +1,783 @@
+// 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, 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;
+
+	timeout = state->meas_interval * (1000 + SCD30_EXTRA_TIMEOUT_PER_S);
+	timeout = msecs_to_jiffies(timeout);
+	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 timeout = state->meas_interval * SCD30_EXTRA_TIMEOUT_PER_S;
+	int 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:
+		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_CALIBSCALE:
+		*val = state->pressure_comp / 10;
+		*val2 = (state->pressure_comp % 10) * 100000;
+		ret = IIO_VAL_INT_PLUS_MICRO;
+		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_CALIBSCALE:
+		val = (val * 1000000 + val2) / 100000;
+		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;
+	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_CALIBSCALE:
+		return IIO_VAL_INT_PLUS_MICRO;
+	case IIO_CHAN_INFO_CALIBBIAS:
+		return IIO_VAL_INT;
+	}
+
+	return -EINVAL;
+}
+
+static const int scd30_pressure_calibscale_available[] = {
+	SCD30_PRESSURE_COMP_MIN_MBAR / 10, 0,
+	0, 100000,
+	SCD30_PRESSURE_COMP_MAX_MBAR / 10, 0,
+};
+
+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_CALIBSCALE:
+		*vals = scd30_pressure_calibscale_available;
+		*type = IIO_VAL_INT_PLUS_MICRO;
+
+		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);
+	int ret;
+	u16 val;
+
+	ret = kstrtou16(buf, 0, &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[] = {
+	{
+		.type = IIO_PRESSURE,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_CALIBSCALE),
+		.info_mask_separate_available = BIT(IIO_CHAN_INFO_CALIBSCALE),
+		.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 = { 0, };
+	int ret;
+
+	mutex_lock(&state->lock);
+	if (!iio_trigger_using_own(indio_dev))
+		ret = scd30_read_poll(state);
+	else
+		ret = scd30_read_meas(state);
+	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->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)) {
+		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");
-- 
2.26.2

[PATCH v3 2/4] iio: chemical: scd30: add I2C interface driver

[Tomasz Duszynski]

Add I2C interface driver for the SCD30 sensor.

Signed-off-by: Tomasz Duszynski <tomasz.duszynski@octakon.com>
---
 MAINTAINERS                      |   1 +
 drivers/iio/chemical/Kconfig     |  11 +++
 drivers/iio/chemical/Makefile    |   1 +
 drivers/iio/chemical/scd30_i2c.c | 134 +++++++++++++++++++++++++++++++
 4 files changed, 147 insertions(+)
 create mode 100644 drivers/iio/chemical/scd30_i2c.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 41a509cca6f1..13aed3473b7e 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -15142,6 +15142,7 @@ M:	Tomasz Duszynski <tomasz.duszynski@octakon.com>
 S:	Maintained
 F:	drivers/iio/chemical/scd30.h
 F:	drivers/iio/chemical/scd30_core.c
+F:	drivers/iio/chemical/scd30_i2c.c
 
 SENSIRION SPS30 AIR POLLUTION SENSOR DRIVER
 M:	Tomasz Duszynski <tduszyns@gmail.com>
diff --git a/drivers/iio/chemical/Kconfig b/drivers/iio/chemical/Kconfig
index 99e852b67e55..970d34888c2e 100644
--- a/drivers/iio/chemical/Kconfig
+++ b/drivers/iio/chemical/Kconfig
@@ -96,6 +96,17 @@ config SCD30_CORE
 	  To compile this driver as a module, choose M here: the module will
 	  be called scd30_core.
 
+config SCD30_I2C
+	tristate "SCD30 carbon dioxide sensor I2C driver"
+	depends on SCD30_CORE && I2C
+	select CRC8
+	help
+	  Say Y here to build support for the Sensirion SCD30 I2C interface
+	  driver.
+
+	  To compile this driver as a module, choose M here: the module will
+	  be called scd30_i2c.
+
 config SENSIRION_SGP30
 	tristate "Sensirion SGPxx gas sensors"
 	depends on I2C
diff --git a/drivers/iio/chemical/Makefile b/drivers/iio/chemical/Makefile
index c9804b041ecd..0966ca34e34b 100644
--- a/drivers/iio/chemical/Makefile
+++ b/drivers/iio/chemical/Makefile
@@ -13,6 +13,7 @@ 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-$(CONFIG_SCD30_I2C) += scd30_i2c.o
 obj-$(CONFIG_SENSIRION_SGP30)	+= sgp30.o
 obj-$(CONFIG_SPS30) += sps30.o
 obj-$(CONFIG_VZ89X)		+= vz89x.o
diff --git a/drivers/iio/chemical/scd30_i2c.c b/drivers/iio/chemical/scd30_i2c.c
new file mode 100644
index 000000000000..a6b532b83669
--- /dev/null
+++ b/drivers/iio/chemical/scd30_i2c.c
@@ -0,0 +1,134 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Sensirion SCD30 carbon dioxide sensor i2c driver
+ *
+ * Copyright (c) 2020 Tomasz Duszynski <tomasz.duszynski@octakon.com>
+ *
+ * I2C slave address: 0x61
+ */
+#include <linux/crc8.h>
+#include <linux/device.h>
+#include <linux/errno.h>
+#include <linux/i2c.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/types.h>
+#include <asm/unaligned.h>
+
+#include "scd30.h"
+
+#define SCD30_I2C_MAX_BUF_SIZE 18
+#define SCD30_I2C_CRC8_POLYNOMIAL 0x31
+
+static u16 scd30_i2c_cmd_lookup_tbl[] = {
+	[CMD_START_MEAS] = 0x0010,
+	[CMD_STOP_MEAS] = 0x0104,
+	[CMD_MEAS_INTERVAL] = 0x4600,
+	[CMD_MEAS_READY] = 0x0202,
+	[CMD_READ_MEAS] = 0x0300,
+	[CMD_ASC] = 0x5306,
+	[CMD_FRC] = 0x5204,
+	[CMD_TEMP_OFFSET] = 0x5403,
+	[CMD_FW_VERSION] = 0xd100,
+	[CMD_RESET] = 0xd304,
+};
+
+DECLARE_CRC8_TABLE(scd30_i2c_crc8_tbl);
+
+static int scd30_i2c_xfer(struct scd30_state *state, char *txbuf, int txsize,
+			  char *rxbuf, int rxsize)
+{
+	struct i2c_client *client = to_i2c_client(state->dev);
+	int ret;
+
+	/*
+	 * repeated start is not supported hence instead of sending two i2c
+	 * messages in a row we send one by one
+	 */
+	ret = i2c_master_send(client, txbuf, txsize);
+	if (ret != txsize)
+		return ret < 0 ? ret : -EIO;
+
+	if (!rxbuf)
+		return 0;
+
+	ret = i2c_master_recv(client, rxbuf, rxsize);
+	if (ret != rxsize)
+		return ret < 0 ? ret : -EIO;
+
+	return 0;
+}
+
+static int scd30_i2c_command(struct scd30_state *state, enum scd30_cmd cmd,
+			     u16 arg, void *response, int size)
+{
+	char crc, buf[SCD30_I2C_MAX_BUF_SIZE], *rsp = response;
+	int i, ret;
+
+	put_unaligned_be16(scd30_i2c_cmd_lookup_tbl[cmd], buf);
+	i = 2;
+
+	if (rsp) {
+		/* each two bytes are followed by a crc8 */
+		size += size / 2;
+	} else {
+		put_unaligned_be16(arg, buf + i);
+		crc = crc8(scd30_i2c_crc8_tbl, buf + i, 2, CRC8_INIT_VALUE);
+		i += 2;
+		buf[i] = crc;
+		i += 1;
+
+		/* commands below don't take an argument */
+		if ((cmd == CMD_STOP_MEAS) || (cmd == CMD_RESET))
+			i -= 3;
+	}
+
+	ret = scd30_i2c_xfer(state, buf, i, buf, size);
+	if (ret)
+		return ret;
+
+	/* validate received data and strip off crc bytes */
+	for (i = 0; i < size; i += 3) {
+		crc = crc8(scd30_i2c_crc8_tbl, buf + i, 2, CRC8_INIT_VALUE);
+		if (crc != buf[i + 2]) {
+			dev_err(state->dev, "data integrity check failed\n");
+			return -EIO;
+		}
+
+		*rsp++ = buf[i];
+		*rsp++ = buf[i + 1];
+	}
+
+	return 0;
+}
+
+static int scd30_i2c_probe(struct i2c_client *client)
+{
+	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
+		return -EOPNOTSUPP;
+
+	crc8_populate_msb(scd30_i2c_crc8_tbl, SCD30_I2C_CRC8_POLYNOMIAL);
+
+	return scd30_probe(&client->dev, client->irq, client->name, NULL,
+			   scd30_i2c_command);
+}
+
+static const struct of_device_id scd30_i2c_of_match[] = {
+	{ .compatible = "sensirion,scd30" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, scd30_i2c_of_match);
+
+static struct i2c_driver scd30_i2c_driver = {
+	.driver = {
+		.name = KBUILD_MODNAME,
+		.of_match_table = scd30_i2c_of_match,
+		.pm = &scd30_pm_ops,
+	},
+	.probe_new = scd30_i2c_probe,
+};
+module_i2c_driver(scd30_i2c_driver);
+
+MODULE_AUTHOR("Tomasz Duszynski <tomasz.duszynski@octakon.com>");
+MODULE_DESCRIPTION("Sensirion SCD30 carbon dioxide sensor i2c driver");
+MODULE_LICENSE("GPL v2");
-- 
2.26.2

[PATCH v3 3/4] iio: chemical: scd30: add serial interface driver

[Tomasz Duszynski]

Add serial interface driver for the SCD30 sensor.

Signed-off-by: Tomasz Duszynski <tomasz.duszynski@octakon.com>
---
 MAINTAINERS                         |   1 +
 drivers/iio/chemical/Kconfig        |  11 ++
 drivers/iio/chemical/Makefile       |   1 +
 drivers/iio/chemical/scd30_serial.c | 266 ++++++++++++++++++++++++++++
 4 files changed, 279 insertions(+)
 create mode 100644 drivers/iio/chemical/scd30_serial.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 13aed3473b7e..5db4b446c8ba 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -15143,6 +15143,7 @@ S:	Maintained
 F:	drivers/iio/chemical/scd30.h
 F:	drivers/iio/chemical/scd30_core.c
 F:	drivers/iio/chemical/scd30_i2c.c
+F:	drivers/iio/chemical/scd30_serial.c
 
 SENSIRION SPS30 AIR POLLUTION SENSOR DRIVER
 M:	Tomasz Duszynski <tduszyns@gmail.com>
diff --git a/drivers/iio/chemical/Kconfig b/drivers/iio/chemical/Kconfig
index 970d34888c2e..10bb431bc3ce 100644
--- a/drivers/iio/chemical/Kconfig
+++ b/drivers/iio/chemical/Kconfig
@@ -107,6 +107,17 @@ config SCD30_I2C
 	  To compile this driver as a module, choose M here: the module will
 	  be called scd30_i2c.
 
+config SCD30_SERIAL
+	tristate "SCD30 carbon dioxide sensor serial driver"
+	depends on SCD30_CORE && SERIAL_DEV_BUS
+	select CRC16
+	help
+	  Say Y here to build support for the Sensirion SCD30 serial interface
+	  driver.
+
+	  To compile this driver as a module, choose M here: the module will
+	  be called scd30_serial.
+
 config SENSIRION_SGP30
 	tristate "Sensirion SGPxx gas sensors"
 	depends on I2C
diff --git a/drivers/iio/chemical/Makefile b/drivers/iio/chemical/Makefile
index 0966ca34e34b..fef63dd5bf92 100644
--- a/drivers/iio/chemical/Makefile
+++ b/drivers/iio/chemical/Makefile
@@ -14,6 +14,7 @@ obj-$(CONFIG_IAQCORE)		+= ams-iaq-core.o
 obj-$(CONFIG_PMS7003) += pms7003.o
 obj-$(CONFIG_SCD30_CORE) += scd30_core.o
 obj-$(CONFIG_SCD30_I2C) += scd30_i2c.o
+obj-$(CONFIG_SCD30_SERIAL) += scd30_serial.o
 obj-$(CONFIG_SENSIRION_SGP30)	+= sgp30.o
 obj-$(CONFIG_SPS30) += sps30.o
 obj-$(CONFIG_VZ89X)		+= vz89x.o
diff --git a/drivers/iio/chemical/scd30_serial.c b/drivers/iio/chemical/scd30_serial.c
new file mode 100644
index 000000000000..07d7d3110fe0
--- /dev/null
+++ b/drivers/iio/chemical/scd30_serial.c
@@ -0,0 +1,266 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Sensirion SCD30 carbon dioxide sensor serial driver
+ *
+ * Copyright (c) 2020 Tomasz Duszynski <tomasz.duszynski@octakon.com>
+ */
+#include <linux/crc16.h>
+#include <linux/device.h>
+#include <linux/errno.h>
+#include <linux/iio/iio.h>
+#include <linux/jiffies.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/property.h>
+#include <linux/serdev.h>
+#include <linux/string.h>
+#include <linux/types.h>
+#include <asm/unaligned.h>
+
+#include "scd30.h"
+
+#define SCD30_SERDEV_ADDR 0x61
+#define SCD30_SERDEV_WRITE 0x06
+#define SCD30_SERDEV_READ 0x03
+#define SCD30_SERDEV_MAX_BUF_SIZE 17
+#define SCD30_SERDEV_RX_HEADER_SIZE 3
+#define SCD30_SERDEV_CRC_SIZE 2
+#define SCD30_SERDEV_TIMEOUT msecs_to_jiffies(200)
+
+struct scd30_serdev_priv {
+	struct completion meas_ready;
+	char *buf;
+	int num_expected;
+	int num;
+};
+
+static u16 scd30_serdev_cmd_lookup_tbl[] = {
+	[CMD_START_MEAS] = 0x0036,
+	[CMD_STOP_MEAS] = 0x0037,
+	[CMD_MEAS_INTERVAL] = 0x0025,
+	[CMD_MEAS_READY] = 0x0027,
+	[CMD_READ_MEAS] = 0x0028,
+	[CMD_ASC] = 0x003a,
+	[CMD_FRC] = 0x0039,
+	[CMD_TEMP_OFFSET] = 0x003b,
+	[CMD_FW_VERSION] = 0x0020,
+	[CMD_RESET] = 0x0034,
+};
+
+static u16 scd30_serdev_calc_crc(const char *buf, int size)
+{
+	return crc16(0xffff, buf, size);
+}
+
+static int scd30_serdev_xfer(struct scd30_state *state, char *txbuf, int txsize,
+			     char *rxbuf, int rxsize)
+{
+	struct serdev_device *serdev = to_serdev_device(state->dev);
+	struct scd30_serdev_priv *priv = state->priv;
+	int ret;
+
+	priv->buf = rxbuf;
+	priv->num_expected = rxsize;
+	priv->num = 0;
+
+	ret = serdev_device_write(serdev, txbuf, txsize, SCD30_SERDEV_TIMEOUT);
+	if (ret < txsize)
+		return ret < 0 ? ret : -EIO;
+
+	ret = wait_for_completion_interruptible_timeout(&priv->meas_ready,
+							SCD30_SERDEV_TIMEOUT);
+	if (ret > 0)
+		ret = 0;
+	else if (!ret)
+		ret = -ETIMEDOUT;
+
+	return ret;
+}
+
+static int scd30_serdev_command(struct scd30_state *state, enum scd30_cmd cmd,
+				u16 arg, void *response, int size)
+{
+	/*
+	 * Communication over serial line is based on modbus protocol (or rather
+	 * its variation called modbus over serial to be precise). Upon
+	 * receiving a request device should reply with response.
+	 *
+	 * Frame below represents a request message. Each field takes
+	 * exactly one byte.
+	 *
+	 * +------+------+-----+-----+-------+-------+-----+-----+
+	 * | dev  | op   | reg | reg | byte1 | byte0 | crc | crc |
+	 * | addr | code | msb | lsb |       |       | lsb | msb |
+	 * +------+------+-----+-----+-------+-------+-----+-----+
+	 *
+	 * The message device replies with depends on the 'op code' field from
+	 * the request. In case it was set to SCD30_SERDEV_WRITE sensor should
+	 * reply with unchanged request. Otherwise 'op code' was set to
+	 * SCD30_SERDEV_READ and response looks like the one below. As with
+	 * request, each field takes one byte.
+	 *
+	 * +------+------+--------+-------+-----+-------+-----+-----+
+	 * | dev  | op   | num of | byte0 | ... | byteN | crc | crc |
+	 * | addr | code | bytes  |       |     |       | lsb | msb |
+	 * +------+------+--------+-------+-----+-------+-----+-----+
+	 */
+	char txbuf[SCD30_SERDEV_MAX_BUF_SIZE] = { SCD30_SERDEV_ADDR },
+	     rxbuf[SCD30_SERDEV_MAX_BUF_SIZE], *rsp = response;
+	int ret, rxsize, txsize = 2;
+	u16 crc;
+
+	put_unaligned_be16(scd30_serdev_cmd_lookup_tbl[cmd], txbuf + txsize);
+	txsize += 2;
+
+	if (rsp) {
+		txbuf[1] = SCD30_SERDEV_READ;
+		if (cmd == CMD_READ_MEAS)
+			/* number of u16 words to read */
+			put_unaligned_be16(size / 2, txbuf + txsize);
+		else
+			put_unaligned_be16(0x0001, txbuf + txsize);
+		txsize += 2;
+		crc = scd30_serdev_calc_crc(txbuf, txsize);
+		put_unaligned_le16(crc, txbuf + txsize);
+		txsize += 2;
+		rxsize = SCD30_SERDEV_RX_HEADER_SIZE + size +
+			 SCD30_SERDEV_CRC_SIZE;
+	} else {
+		if ((cmd == CMD_STOP_MEAS) || (cmd == CMD_RESET))
+			arg = 0x0001;
+
+		txbuf[1] = SCD30_SERDEV_WRITE;
+		put_unaligned_be16(arg, txbuf + txsize);
+		txsize += 2;
+		crc = scd30_serdev_calc_crc(txbuf, txsize);
+		put_unaligned_le16(crc, txbuf + txsize);
+		txsize += 2;
+		rxsize = txsize;
+	}
+
+	ret = scd30_serdev_xfer(state, txbuf, txsize, rxbuf, rxsize);
+	if (ret)
+		return ret;
+
+	switch (txbuf[1]) {
+	case SCD30_SERDEV_WRITE:
+		if (memcmp(txbuf, txbuf, txsize)) {
+			dev_err(state->dev, "wrong message received\n");
+			return -EIO;
+		}
+		break;
+	case SCD30_SERDEV_READ:
+		if (rxbuf[2] != (rxsize -
+				 SCD30_SERDEV_RX_HEADER_SIZE -
+				 SCD30_SERDEV_CRC_SIZE)) {
+			dev_err(state->dev,
+				"received data size does not match header\n");
+			return -EIO;
+		}
+
+		rxsize -= SCD30_SERDEV_CRC_SIZE;
+		crc = get_unaligned_le16(rxbuf + rxsize);
+		if (crc != scd30_serdev_calc_crc(rxbuf, rxsize)) {
+			dev_err(state->dev, "data integrity check failed\n");
+			return -EIO;
+		}
+
+		rxsize -= SCD30_SERDEV_RX_HEADER_SIZE;
+		memcpy(rsp, rxbuf + SCD30_SERDEV_RX_HEADER_SIZE, rxsize);
+		break;
+	default:
+		dev_err(state->dev, "received unknown op code\n");
+		return -EIO;
+	}
+
+	return 0;
+}
+
+static int scd30_serdev_receive_buf(struct serdev_device *serdev,
+				    const unsigned char *buf, size_t size)
+{
+	struct iio_dev *indio_dev = dev_get_drvdata(&serdev->dev);
+	struct scd30_serdev_priv *priv;
+	struct scd30_state *state;
+	int num;
+
+	if (!indio_dev)
+		return 0;
+
+	state = iio_priv(indio_dev);
+	priv = state->priv;
+
+	/* just in case sensor puts some unexpected bytes on the bus */
+	if (!priv->buf)
+		return 0;
+
+	if (priv->num + size >= priv->num_expected)
+		num = priv->num_expected - priv->num;
+	else
+		num = size;
+
+	memcpy(priv->buf + priv->num, buf, num);
+	priv->num += num;
+
+	if (priv->num == priv->num_expected) {
+		priv->buf = NULL;
+		complete(&priv->meas_ready);
+	}
+
+	return num;
+}
+
+static const struct serdev_device_ops scd30_serdev_ops = {
+	.receive_buf = scd30_serdev_receive_buf,
+	.write_wakeup = serdev_device_write_wakeup,
+};
+
+static int scd30_serdev_probe(struct serdev_device *serdev)
+{
+	struct device *dev = &serdev->dev;
+	struct scd30_serdev_priv *priv;
+	int irq, ret;
+
+	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	init_completion(&priv->meas_ready);
+	serdev_device_set_client_ops(serdev, &scd30_serdev_ops);
+
+	ret = devm_serdev_device_open(dev, serdev);
+	if (ret)
+		return ret;
+
+	serdev_device_set_baudrate(serdev, 19200);
+	serdev_device_set_flow_control(serdev, false);
+
+	ret = serdev_device_set_parity(serdev, SERDEV_PARITY_NONE);
+	if (ret)
+		return ret;
+
+	irq = fwnode_irq_get(dev_fwnode(dev), 0);
+
+	return scd30_probe(dev, irq, KBUILD_MODNAME, priv,
+			   scd30_serdev_command);
+}
+
+static const struct of_device_id scd30_serdev_of_match[] = {
+	{ .compatible = "sensirion,scd30" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, scd30_serdev_of_match);
+
+static struct serdev_device_driver scd30_serdev_driver = {
+	.driver = {
+		.name = KBUILD_MODNAME,
+		.of_match_table = scd30_serdev_of_match,
+		.pm = &scd30_pm_ops,
+	},
+	.probe = scd30_serdev_probe,
+};
+module_serdev_device_driver(scd30_serdev_driver);
+
+MODULE_AUTHOR("Tomasz Duszynski <tomasz.duszynski@octakon.com>");
+MODULE_DESCRIPTION("Sensirion SCD30 carbon dioxide sensor serial driver");
+MODULE_LICENSE("GPL v2");
-- 
2.26.2

[PATCH v3 4/4] dt-bindings: iio: scd30: add device binding file

[Tomasz Duszynski]

Add SCD30 sensor binding file.

Signed-off-by: Tomasz Duszynski <tomasz.duszynski@octakon.com>
---
 .../iio/chemical/sensirion,scd30.yaml         | 68 +++++++++++++++++++
 MAINTAINERS                                   |  1 +
 2 files changed, 69 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/chemical/sensirion,scd30.yaml

diff --git a/Documentation/devicetree/bindings/iio/chemical/sensirion,scd30.yaml b/Documentation/devicetree/bindings/iio/chemical/sensirion,scd30.yaml
new file mode 100644
index 000000000000..40d87346ff4c
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/chemical/sensirion,scd30.yaml
@@ -0,0 +1,68 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/chemical/sensirion,scd30.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Sensirion SCD30 carbon dioxide sensor
+
+maintainers:
+  - Tomasz Duszynski <tomasz.duszynski@octakon.com>
+
+description: |
+  Air quality sensor capable of measuring co2 concentration, temperature
+  and relative humidity.
+
+properties:
+  compatible:
+    enum:
+      - sensirion,scd30
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+  vdd-supply: true
+
+  sensirion,sel-gpios:
+    description: GPIO connected to the SEL line
+    maxItems: 1
+
+  sensirion,pwm-gpios:
+    description: GPIO connected to the PWM line
+    maxItems: 1
+
+required:
+  - compatible
+
+additionalProperties: false
+
+examples:
+  - |
+    # include <dt-bindings/interrupt-controller/irq.h>
+    i2c {
+      #address-cells = <1>;
+      #size-cells = <0>;
+
+      co2-sensor@61 {
+        compatible = "sensirion,scd30";
+        reg = <0x61>;
+        vdd-supply = <&vdd>;
+        interrupt-parent = <&gpio0>;
+        interrupts = <0 IRQ_TYPE_LEVEL_HIGH>;
+      };
+    };
+  - |
+    # include <dt-bindings/interrupt-controller/irq.h>
+    serial {
+      co2-sensor {
+        compatible = "sensirion,scd30";
+        vdd-supply = <&vdd>;
+        interrupt-parent = <&gpio0>;
+        interrupts = <0 IRQ_TYPE_LEVEL_HIGH>;
+      };
+    };
+
+...
diff --git a/MAINTAINERS b/MAINTAINERS
index 5db4b446c8ba..0ab9cf39e051 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -15140,6 +15140,7 @@ F:	include/uapi/linux/phantom.h
 SENSIRION SCD30 CARBON DIOXIDE SENSOR DRIVER
 M:	Tomasz Duszynski <tomasz.duszynski@octakon.com>
 S:	Maintained
+F:	Documentation/devicetree/bindings/iio/chemical/sensirion,scd30.yaml
 F:	drivers/iio/chemical/scd30.h
 F:	drivers/iio/chemical/scd30_core.c
 F:	drivers/iio/chemical/scd30_i2c.c
-- 
2.26.2

Re: [PATCH v3 0/4] Add support for SCD30 sensor

[Andy Shevchenko]

On Tue, Jun 2, 2020 at 7:49 PM Tomasz Duszynski
<tomasz.duszynski@octakon.com> wrote:
>
> Following series adds support for Sensirion SCD30 sensor module capable of
> measuring carbon dioxide, temperature and relative humidity. CO2 measurements
> base on NDIR principle while temperature and relative humidity are measured by
> the on board SHT31. As for sensor communication, both I2C and serial interfaces
> are supported.

Btw, since we have relaxed 80 limit to 100, I recommend to reconsider
some lines to be joined.

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v3 3/4] iio: chemical: scd30: add serial interface driver

[Andy Shevchenko]

On Tue, Jun 2, 2020 at 7:49 PM Tomasz Duszynski
<tomasz.duszynski@octakon.com> wrote:
>
> Add serial interface driver for the SCD30 sensor.

...

> +static u16 scd30_serdev_cmd_lookup_tbl[] = {
> +       [CMD_START_MEAS] = 0x0036,
> +       [CMD_STOP_MEAS] = 0x0037,
> +       [CMD_MEAS_INTERVAL] = 0x0025,
> +       [CMD_MEAS_READY] = 0x0027,
> +       [CMD_READ_MEAS] = 0x0028,
> +       [CMD_ASC] = 0x003a,
> +       [CMD_FRC] = 0x0039,
> +       [CMD_TEMP_OFFSET] = 0x003b,
> +       [CMD_FW_VERSION] = 0x0020,
> +       [CMD_RESET] = 0x0034,

Hmm... Can't we keep them ordered by value?

> +};

...

> +       ret = wait_for_completion_interruptible_timeout(&priv->meas_ready,
> +                                                       SCD30_SERDEV_TIMEOUT);
> +       if (ret > 0)
> +               ret = 0;
> +       else if (!ret)
> +               ret = -ETIMEDOUT;
> +
> +       return ret;

Perhaps

  if (ret < 0)
    return ret;
  if (ret == 0)
    return -ETIMEDOUT;
  return 0;

?

...

> +       char txbuf[SCD30_SERDEV_MAX_BUF_SIZE] = { SCD30_SERDEV_ADDR },
> +            rxbuf[SCD30_SERDEV_MAX_BUF_SIZE], *rsp = response;

Please, apply type to each variable separately.

...

> +       switch (txbuf[1]) {
> +       case SCD30_SERDEV_WRITE:

> +               if (memcmp(txbuf, txbuf, txsize)) {

I'm not sure I understand this.

> +                       dev_err(state->dev, "wrong message received\n");
> +                       return -EIO;
> +               }
> +               break;
> +       case SCD30_SERDEV_READ:

> +               if (rxbuf[2] != (rxsize -
> +                                SCD30_SERDEV_RX_HEADER_SIZE -
> +                                SCD30_SERDEV_CRC_SIZE)) {

Perhaps you can come up with better indentation/ line split?

> +                       dev_err(state->dev,
> +                               "received data size does not match header\n");
> +                       return -EIO;
> +               }
> +
> +               rxsize -= SCD30_SERDEV_CRC_SIZE;
> +               crc = get_unaligned_le16(rxbuf + rxsize);
> +               if (crc != scd30_serdev_calc_crc(rxbuf, rxsize)) {
> +                       dev_err(state->dev, "data integrity check failed\n");
> +                       return -EIO;
> +               }
> +
> +               rxsize -= SCD30_SERDEV_RX_HEADER_SIZE;
> +               memcpy(rsp, rxbuf + SCD30_SERDEV_RX_HEADER_SIZE, rxsize);
> +               break;
> +       default:
> +               dev_err(state->dev, "received unknown op code\n");
> +               return -EIO;
> +       }
> +
> +       return 0;
> +}

...

> +static struct serdev_device_driver scd30_serdev_driver = {
> +       .driver = {

> +               .name = KBUILD_MODNAME,

This is not the best what we can do. The name is an ABI and better if
it will be constant (independent on file name).

> +               .of_match_table = scd30_serdev_of_match,
> +               .pm = &scd30_pm_ops,
> +       },
> +       .probe = scd30_serdev_probe,
> +};

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v3 2/4] iio: chemical: scd30: add I2C interface driver

[Andy Shevchenko]

On Tue, Jun 2, 2020 at 7:49 PM Tomasz Duszynski
<tomasz.duszynski@octakon.com> wrote:
>
> Add I2C interface driver for the SCD30 sensor.

...

> +static u16 scd30_i2c_cmd_lookup_tbl[] = {
> +       [CMD_START_MEAS] = 0x0010,
> +       [CMD_STOP_MEAS] = 0x0104,
> +       [CMD_MEAS_INTERVAL] = 0x4600,
> +       [CMD_MEAS_READY] = 0x0202,
> +       [CMD_READ_MEAS] = 0x0300,
> +       [CMD_ASC] = 0x5306,
> +       [CMD_FRC] = 0x5204,
> +       [CMD_TEMP_OFFSET] = 0x5403,
> +       [CMD_FW_VERSION] = 0xd100,
> +       [CMD_RESET] = 0xd304,

Keep sorted by value?

> +};

...

> +       ret = i2c_master_send(client, txbuf, txsize);

> +       if (ret != txsize)
> +               return ret < 0 ? ret : -EIO;

Wouldn't be better

  if (ret < 0)
    return ret;
  if (ret != txsize)
    return -EIO;

?

> +       if (!rxbuf)
> +               return 0;
> +
> +       ret = i2c_master_recv(client, rxbuf, rxsize);

> +       if (ret != rxsize)
> +               return ret < 0 ? ret : -EIO;

Ditto.

...

> +static int scd30_i2c_command(struct scd30_state *state, enum scd30_cmd cmd,
> +                            u16 arg, void *response, int size)
> +{
> +       char crc, buf[SCD30_I2C_MAX_BUF_SIZE], *rsp = response;
> +       int i, ret;

i -> offset ?

> +       put_unaligned_be16(scd30_i2c_cmd_lookup_tbl[cmd], buf);
> +       i = 2;
> +
> +       if (rsp) {
> +               /* each two bytes are followed by a crc8 */
> +               size += size / 2;
> +       } else {
> +               put_unaligned_be16(arg, buf + i);
> +               crc = crc8(scd30_i2c_crc8_tbl, buf + i, 2, CRC8_INIT_VALUE);
> +               i += 2;

> +               buf[i] = crc;
> +               i += 1;

buf[offset++] = crc; ?

> +               /* commands below don't take an argument */
> +               if ((cmd == CMD_STOP_MEAS) || (cmd == CMD_RESET))
> +                       i -= 3;
> +       }
> +
> +       ret = scd30_i2c_xfer(state, buf, i, buf, size);
> +       if (ret)
> +               return ret;
> +
> +       /* validate received data and strip off crc bytes */
> +       for (i = 0; i < size; i += 3) {
> +               crc = crc8(scd30_i2c_crc8_tbl, buf + i, 2, CRC8_INIT_VALUE);
> +               if (crc != buf[i + 2]) {
> +                       dev_err(state->dev, "data integrity check failed\n");
> +                       return -EIO;
> +               }
> +

> +               *rsp++ = buf[i];

+ 0 (for the sake of consistency?

> +               *rsp++ = buf[i + 1];
> +       }
> +
> +       return 0;
> +}

...

> +static struct i2c_driver scd30_i2c_driver = {
> +       .driver = {

> +               .name = KBUILD_MODNAME,

Better to hard code.

> +               .of_match_table = scd30_i2c_of_match,
> +               .pm = &scd30_pm_ops,
> +       },
> +       .probe_new = scd30_i2c_probe,
> +};

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v3 2/4] iio: chemical: scd30: add I2C interface driver

[Tomasz Duszynski]

Hello Andy,

On Tue, Jun 02, 2020 at 08:14:13PM +0300, Andy Shevchenko wrote:
> On Tue, Jun 2, 2020 at 7:49 PM Tomasz Duszynski
> <tomasz.duszynski@octakon.com> wrote:
> >
> > Add I2C interface driver for the SCD30 sensor.
>
> ...
>
> > +static u16 scd30_i2c_cmd_lookup_tbl[] = {
> > +       [CMD_START_MEAS] = 0x0010,
> > +       [CMD_STOP_MEAS] = 0x0104,
> > +       [CMD_MEAS_INTERVAL] = 0x4600,
> > +       [CMD_MEAS_READY] = 0x0202,
> > +       [CMD_READ_MEAS] = 0x0300,
> > +       [CMD_ASC] = 0x5306,
> > +       [CMD_FRC] = 0x5204,
> > +       [CMD_TEMP_OFFSET] = 0x5403,
> > +       [CMD_FW_VERSION] = 0xd100,
> > +       [CMD_RESET] = 0xd304,
>
> Keep sorted by value?
>

I'd rather leave it as is simply because order here matches order in
sensor datasheet.

> > +};
>
> ...
>
> > +       ret = i2c_master_send(client, txbuf, txsize);
>
> > +       if (ret != txsize)
> > +               return ret < 0 ? ret : -EIO;
>
> Wouldn't be better
>
>   if (ret < 0)
>     return ret;
>   if (ret != txsize)
>     return -EIO;
>
> ?
>

Hmm, okay. Perhaps slightly easier to read.

> > +       if (!rxbuf)
> > +               return 0;
> > +
> > +       ret = i2c_master_recv(client, rxbuf, rxsize);
>
> > +       if (ret != rxsize)
> > +               return ret < 0 ? ret : -EIO;
>
> Ditto.
>
> ...
>
> > +static int scd30_i2c_command(struct scd30_state *state, enum scd30_cmd cmd,
> > +                            u16 arg, void *response, int size)
> > +{
> > +       char crc, buf[SCD30_I2C_MAX_BUF_SIZE], *rsp = response;
> > +       int i, ret;
>
> i -> offset ?
>

'i' is shorter and I am lazy :).

> > +       put_unaligned_be16(scd30_i2c_cmd_lookup_tbl[cmd], buf);
> > +       i = 2;
> > +
> > +       if (rsp) {
> > +               /* each two bytes are followed by a crc8 */
> > +               size += size / 2;
> > +       } else {
> > +               put_unaligned_be16(arg, buf + i);
> > +               crc = crc8(scd30_i2c_crc8_tbl, buf + i, 2, CRC8_INIT_VALUE);
> > +               i += 2;
>
> > +               buf[i] = crc;
> > +               i += 1;
>
> buf[offset++] = crc; ?
>

I'd rather stick to what I have now. It looks more consistent.

> > +               /* commands below don't take an argument */
> > +               if ((cmd == CMD_STOP_MEAS) || (cmd == CMD_RESET))
> > +                       i -= 3;
> > +       }
> > +
> > +       ret = scd30_i2c_xfer(state, buf, i, buf, size);
> > +       if (ret)
> > +               return ret;
> > +
> > +       /* validate received data and strip off crc bytes */
> > +       for (i = 0; i < size; i += 3) {
> > +               crc = crc8(scd30_i2c_crc8_tbl, buf + i, 2, CRC8_INIT_VALUE);
> > +               if (crc != buf[i + 2]) {
> > +                       dev_err(state->dev, "data integrity check failed\n");
> > +                       return -EIO;
> > +               }
> > +
>
> > +               *rsp++ = buf[i];
>
> + 0 (for the sake of consistency?
>

Adding 0 is a little bit odd.

> > +               *rsp++ = buf[i + 1];
> > +       }
> > +
> > +       return 0;
> > +}
>
> ...
>
> > +static struct i2c_driver scd30_i2c_driver = {
> > +       .driver = {
>
> > +               .name = KBUILD_MODNAME,
>
> Better to hard code.
>

I seriously doubt anyone will ever want to change module name. What for?

> > +               .of_match_table = scd30_i2c_of_match,
> > +               .pm = &scd30_pm_ops,
> > +       },
> > +       .probe_new = scd30_i2c_probe,
> > +};
>
> --
> With Best Regards,
> Andy Shevchenko

Re: [PATCH v3 3/4] iio: chemical: scd30: add serial interface driver

[Tomasz Duszynski]

On Tue, Jun 02, 2020 at 08:04:16PM +0300, Andy Shevchenko wrote:
> On Tue, Jun 2, 2020 at 7:49 PM Tomasz Duszynski
> <tomasz.duszynski@octakon.com> wrote:
> >
> > Add serial interface driver for the SCD30 sensor.
>
> ...
>
> > +static u16 scd30_serdev_cmd_lookup_tbl[] = {
> > +       [CMD_START_MEAS] = 0x0036,
> > +       [CMD_STOP_MEAS] = 0x0037,
> > +       [CMD_MEAS_INTERVAL] = 0x0025,
> > +       [CMD_MEAS_READY] = 0x0027,
> > +       [CMD_READ_MEAS] = 0x0028,
> > +       [CMD_ASC] = 0x003a,
> > +       [CMD_FRC] = 0x0039,
> > +       [CMD_TEMP_OFFSET] = 0x003b,
> > +       [CMD_FW_VERSION] = 0x0020,
> > +       [CMD_RESET] = 0x0034,
>
> Hmm... Can't we keep them ordered by value?
>
> > +};
>
> ...
>
> > +       ret = wait_for_completion_interruptible_timeout(&priv->meas_ready,
> > +                                                       SCD30_SERDEV_TIMEOUT);
> > +       if (ret > 0)
> > +               ret = 0;
> > +       else if (!ret)
> > +               ret = -ETIMEDOUT;
> > +
> > +       return ret;
>
> Perhaps
>
>   if (ret < 0)
>     return ret;
>   if (ret == 0)
>     return -ETIMEDOUT;
>   return 0;
>
> ?

Matter of style but since I will be doing other changes I can touch that
too.

>
> ...
>
> > +       char txbuf[SCD30_SERDEV_MAX_BUF_SIZE] = { SCD30_SERDEV_ADDR },
> > +            rxbuf[SCD30_SERDEV_MAX_BUF_SIZE], *rsp = response;
>
> Please, apply type to each variable separately.
>

Fine.

> ...
>
> > +       switch (txbuf[1]) {
> > +       case SCD30_SERDEV_WRITE:
>
> > +               if (memcmp(txbuf, txbuf, txsize)) {
>
> I'm not sure I understand this.
>

Ah, thanks for catching this. tx should be compared to rx.

> > +                       dev_err(state->dev, "wrong message received\n");
> > +                       return -EIO;
> > +               }
> > +               break;
> > +       case SCD30_SERDEV_READ:
>
> > +               if (rxbuf[2] != (rxsize -
> > +                                SCD30_SERDEV_RX_HEADER_SIZE -
> > +                                SCD30_SERDEV_CRC_SIZE)) {
>
> Perhaps you can come up with better indentation/ line split?
>

I'd rather leave it as is.

> > +                       dev_err(state->dev,
> > +                               "received data size does not match header\n");
> > +                       return -EIO;
> > +               }
> > +
> > +               rxsize -= SCD30_SERDEV_CRC_SIZE;
> > +               crc = get_unaligned_le16(rxbuf + rxsize);
> > +               if (crc != scd30_serdev_calc_crc(rxbuf, rxsize)) {
> > +                       dev_err(state->dev, "data integrity check failed\n");
> > +                       return -EIO;
> > +               }
> > +
> > +               rxsize -= SCD30_SERDEV_RX_HEADER_SIZE;
> > +               memcpy(rsp, rxbuf + SCD30_SERDEV_RX_HEADER_SIZE, rxsize);
> > +               break;
> > +       default:
> > +               dev_err(state->dev, "received unknown op code\n");
> > +               return -EIO;
> > +       }
> > +
> > +       return 0;
> > +}
>
> ...
>
> > +static struct serdev_device_driver scd30_serdev_driver = {
> > +       .driver = {
>
> > +               .name = KBUILD_MODNAME,
>
> This is not the best what we can do. The name is an ABI and better if
> it will be constant (independent on file name).
>
> > +               .of_match_table = scd30_serdev_of_match,
> > +               .pm = &scd30_pm_ops,
> > +       },
> > +       .probe = scd30_serdev_probe,
> > +};
>
> --
> With Best Regards,
> Andy Shevchenko

Re: [PATCH v3 0/4] Add support for SCD30 sensor

[Tomasz Duszynski]

On Tue, Jun 02, 2020 at 07:55:55PM +0300, Andy Shevchenko wrote:
> On Tue, Jun 2, 2020 at 7:49 PM Tomasz Duszynski
> <tomasz.duszynski@octakon.com> wrote:
> >
> > Following series adds support for Sensirion SCD30 sensor module capable of
> > measuring carbon dioxide, temperature and relative humidity. CO2 measurements
> > base on NDIR principle while temperature and relative humidity are measured by
> > the on board SHT31. As for sensor communication, both I2C and serial interfaces
> > are supported.
>
> Btw, since we have relaxed 80 limit to 100, I recommend to reconsider
> some lines to be joined.
>

Heh, that particular change is becoming more viral that corona itself these days.

> --
> With Best Regards,
> Andy Shevchenko

Re: [PATCH v3 3/4] iio: chemical: scd30: add serial interface driver

[Tomasz Duszynski]

On Tue, Jun 02, 2020 at 07:57:23PM +0200, Tomasz Duszynski wrote:
> On Tue, Jun 02, 2020 at 08:04:16PM +0300, Andy Shevchenko wrote:
> > On Tue, Jun 2, 2020 at 7:49 PM Tomasz Duszynski
> > <tomasz.duszynski@octakon.com> wrote:
> > >
> > > Add serial interface driver for the SCD30 sensor.
> >
> > ...
> >
> > > +static u16 scd30_serdev_cmd_lookup_tbl[] = {
> > > +       [CMD_START_MEAS] = 0x0036,
> > > +       [CMD_STOP_MEAS] = 0x0037,
> > > +       [CMD_MEAS_INTERVAL] = 0x0025,
> > > +       [CMD_MEAS_READY] = 0x0027,
> > > +       [CMD_READ_MEAS] = 0x0028,
> > > +       [CMD_ASC] = 0x003a,
> > > +       [CMD_FRC] = 0x0039,
> > > +       [CMD_TEMP_OFFSET] = 0x003b,
> > > +       [CMD_FW_VERSION] = 0x0020,
> > > +       [CMD_RESET] = 0x0034,
> >
> > Hmm... Can't we keep them ordered by value?
> >
> > > +};
> >
> > ...
> >
> > > +       ret = wait_for_completion_interruptible_timeout(&priv->meas_ready,
> > > +                                                       SCD30_SERDEV_TIMEOUT);
> > > +       if (ret > 0)
> > > +               ret = 0;
> > > +       else if (!ret)
> > > +               ret = -ETIMEDOUT;
> > > +
> > > +       return ret;
> >
> > Perhaps
> >
> >   if (ret < 0)
> >     return ret;
> >   if (ret == 0)
> >     return -ETIMEDOUT;
> >   return 0;
> >
> > ?
>
> Matter of style but since I will be doing other changes I can touch that
> too.
>
> >
> > ...
> >
> > > +       char txbuf[SCD30_SERDEV_MAX_BUF_SIZE] = { SCD30_SERDEV_ADDR },
> > > +            rxbuf[SCD30_SERDEV_MAX_BUF_SIZE], *rsp = response;
> >
> > Please, apply type to each variable separately.
> >
>
> Fine.
>
> > ...
> >
> > > +       switch (txbuf[1]) {
> > > +       case SCD30_SERDEV_WRITE:
> >
> > > +               if (memcmp(txbuf, txbuf, txsize)) {
> >
> > I'm not sure I understand this.
> >
>
> Ah, thanks for catching this. tx should be compared to rx.
>
> > > +                       dev_err(state->dev, "wrong message received\n");
> > > +                       return -EIO;
> > > +               }
> > > +               break;
> > > +       case SCD30_SERDEV_READ:
> >
> > > +               if (rxbuf[2] != (rxsize -
> > > +                                SCD30_SERDEV_RX_HEADER_SIZE -
> > > +                                SCD30_SERDEV_CRC_SIZE)) {
> >
> > Perhaps you can come up with better indentation/ line split?
> >
>
> I'd rather leave it as is.
>

On the second thought, that would fit 100 column line.

> > > +                       dev_err(state->dev,
> > > +                               "received data size does not match header\n");
> > > +                       return -EIO;
> > > +               }
> > > +
> > > +               rxsize -= SCD30_SERDEV_CRC_SIZE;
> > > +               crc = get_unaligned_le16(rxbuf + rxsize);
> > > +               if (crc != scd30_serdev_calc_crc(rxbuf, rxsize)) {
> > > +                       dev_err(state->dev, "data integrity check failed\n");
> > > +                       return -EIO;
> > > +               }
> > > +
> > > +               rxsize -= SCD30_SERDEV_RX_HEADER_SIZE;
> > > +               memcpy(rsp, rxbuf + SCD30_SERDEV_RX_HEADER_SIZE, rxsize);
> > > +               break;
> > > +       default:
> > > +               dev_err(state->dev, "received unknown op code\n");
> > > +               return -EIO;
> > > +       }
> > > +
> > > +       return 0;
> > > +}
> >
> > ...
> >
> > > +static struct serdev_device_driver scd30_serdev_driver = {
> > > +       .driver = {
> >
> > > +               .name = KBUILD_MODNAME,
> >
> > This is not the best what we can do. The name is an ABI and better if
> > it will be constant (independent on file name).
> >
> > > +               .of_match_table = scd30_serdev_of_match,
> > > +               .pm = &scd30_pm_ops,
> > > +       },
> > > +       .probe = scd30_serdev_probe,
> > > +};
> >
> > --
> > With Best Regards,
> > Andy Shevchenko