[RFC v2 0/4] iio: new chemical sensor framework and channel types

[RFC v2 0/4] iio: new chemical sensor framework and channel types

[Matt Ranostay]

Changes from RFC v1:
* Removed IIO_MOD_PPM/PPB modifiers
* Fixed issues with driver that would have caused null
  readings
* Return IIO_VAL_INT_PLUS_MICRO/IIO_VAL_INT_PLUS_NANO
  for CO2 and VOC channel readings
* Return IIO_VAL_INT_PLUS_MICRO for IIO_CHAN_INFO_OFFSET
* Add sysfs-bus-iio-chemical-vz89x documentation

Matt Ranostay (4):
  iio: chemical: Add IIO_CONCENTRATION channel type
  iio: resistance: add IIO_RESISTANCE channel type
  devicetree: add SGX Sensortech vendor id
  iio: chemical: add SGX VZ89x VOC sensor support

 Documentation/ABI/testing/sysfs-bus-iio            |  14 ++
 .../ABI/testing/sysfs-bus-iio-chemical-vz89x       |  30 +++
 .../devicetree/bindings/i2c/trivial-devices.txt    |   1 +
 .../devicetree/bindings/vendor-prefixes.txt        |   1 +
 drivers/iio/Kconfig                                |   1 +
 drivers/iio/Makefile                               |   1 +
 drivers/iio/chemical/Makefile                      |   6 +
 drivers/iio/chemical/vz89x.c                       | 236 +++++++++++++++++++++
 drivers/iio/industrialio-core.c                    |   2 +
 include/uapi/linux/iio/types.h                     |   2 +
 10 files changed, 294 insertions(+)
 create mode 100644 Documentation/ABI/testing/sysfs-bus-iio-chemical-vz89x
 create mode 100644 drivers/iio/chemical/Makefile
 create mode 100644 drivers/iio/chemical/vz89x.c

-- 
1.9.1

[RFC v2 1/4] iio: chemical: Add IIO_CONCENTRATION channel type

[Matt Ranostay]

There are air quality sensors that report data back in parts per million
of VOC (Volatile Organic Compounds) which are usually indexed from CO2
or another common pollutant.

This patchset adds an IIO_CONCENTRATION type that returns a percentage
of substance because no other channels types fit this use case.

Signed-off-by: Matt Ranostay <mranostay@gmail.com>
---
 Documentation/ABI/testing/sysfs-bus-iio | 7 +++++++
 drivers/iio/industrialio-core.c         | 1 +
 include/uapi/linux/iio/types.h          | 1 +
 3 files changed, 9 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-bus-iio b/Documentation/ABI/testing/sysfs-bus-iio
index 42d360f..48080b7 100644
--- a/Documentation/ABI/testing/sysfs-bus-iio
+++ b/Documentation/ABI/testing/sysfs-bus-iio
@@ -1459,3 +1459,10 @@ Description:
 		measurements and return the average value as output data. Each
 		value resulted from <type>[_name]_oversampling_ratio measurements
 		is considered as one sample for <type>[_name]_sampling_frequency.
+
+What:		/sys/bus/iio/devices/iio:deviceX/in_concentration_raw
+What:		/sys/bus/iio/devices/iio:deviceX/in_concentrationX_raw
+KernelVersion:	4.3
+Contact:	linux-iio@vger.kernel.org
+Description:
+		Raw (unscaled no offset etc.) precentage reading of a substance.
diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c
index b3fcc2c..58a60a1 100644
--- a/drivers/iio/industrialio-core.c
+++ b/drivers/iio/industrialio-core.c
@@ -75,6 +75,7 @@ static const char * const iio_chan_type_name_spec[] = {
 	[IIO_ENERGY] = "energy",
 	[IIO_DISTANCE] = "distance",
 	[IIO_VELOCITY] = "velocity",
+	[IIO_CONCENTRATION] = "concentration",
 };
 
 static const char * const iio_modifier_names[] = {
diff --git a/include/uapi/linux/iio/types.h b/include/uapi/linux/iio/types.h
index 2f8b117..c5a0e3f 100644
--- a/include/uapi/linux/iio/types.h
+++ b/include/uapi/linux/iio/types.h
@@ -35,6 +35,7 @@ enum iio_chan_type {
 	IIO_ENERGY,
 	IIO_DISTANCE,
 	IIO_VELOCITY,
+	IIO_CONCENTRATION,
 };
 
 enum iio_modifier {
-- 
1.9.1

[RFC v2 2/4] iio: resistance: add IIO_RESISTANCE channel type

[Matt Ranostay]

Signed-off-by: Matt Ranostay <mranostay-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
---
 Documentation/ABI/testing/sysfs-bus-iio | 7 +++++++
 drivers/iio/industrialio-core.c         | 1 +
 include/uapi/linux/iio/types.h          | 1 +
 3 files changed, 9 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-bus-iio b/Documentation/ABI/testing/sysfs-bus-iio
index 48080b7..0f683ed 100644
--- a/Documentation/ABI/testing/sysfs-bus-iio
+++ b/Documentation/ABI/testing/sysfs-bus-iio
@@ -1466,3 +1466,10 @@ KernelVersion:	4.3
 Contact:	linux-iio-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
 Description:
 		Raw (unscaled no offset etc.) precentage reading of a substance.
+
+What:		/sys/bus/iio/devices/iio:deviceX/in_resistance_raw
+What:		/sys/bus/iio/devices/iio:deviceX/in_resistanceX_raw
+KernelVersion:	4.3
+Contact:	linux-iio-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
+Description:
+		Raw (unscaled no offset etc.) resistance reading in ohms.
diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c
index 58a60a1..d61a363 100644
--- a/drivers/iio/industrialio-core.c
+++ b/drivers/iio/industrialio-core.c
@@ -76,6 +76,7 @@ static const char * const iio_chan_type_name_spec[] = {
 	[IIO_DISTANCE] = "distance",
 	[IIO_VELOCITY] = "velocity",
 	[IIO_CONCENTRATION] = "concentration",
+	[IIO_RESISTANCE] = "resistance",
 };
 
 static const char * const iio_modifier_names[] = {
diff --git a/include/uapi/linux/iio/types.h b/include/uapi/linux/iio/types.h
index c5a0e3f..d58319c 100644
--- a/include/uapi/linux/iio/types.h
+++ b/include/uapi/linux/iio/types.h
@@ -36,6 +36,7 @@ enum iio_chan_type {
 	IIO_DISTANCE,
 	IIO_VELOCITY,
 	IIO_CONCENTRATION,
+	IIO_RESISTANCE,
 };
 
 enum iio_modifier {
-- 
1.9.1

[RFC v2 3/4] devicetree: add SGX Sensortech vendor id

[Matt Ranostay]

Signed-off-by: Matt Ranostay <mranostay-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
---
 Documentation/devicetree/bindings/vendor-prefixes.txt | 1 +
 1 file changed, 1 insertion(+)

diff --git a/Documentation/devicetree/bindings/vendor-prefixes.txt b/Documentation/devicetree/bindings/vendor-prefixes.txt
index ac5f0c3..281e8f0 100644
--- a/Documentation/devicetree/bindings/vendor-prefixes.txt
+++ b/Documentation/devicetree/bindings/vendor-prefixes.txt
@@ -191,6 +191,7 @@ sbs	Smart Battery System
 schindler	Schindler
 seagate	Seagate Technology PLC
 semtech	Semtech Corporation
+sgx	SGX Sensortech
 sharp	Sharp Corporation
 sil	Silicon Image
 silabs	Silicon Laboratories
-- 
1.9.1

[RFC v2 4/4] iio: chemical: add SGX VZ89x VOC sensor support

[Matt Ranostay]

Add support for VZ89X sensors VOC and CO2 reporting channels in
percentage which can be converted to part per million.

Signed-off-by: Matt Ranostay <mranostay@gmail.com>
---
 .../ABI/testing/sysfs-bus-iio-chemical-vz89x       |  30 +++
 .../devicetree/bindings/i2c/trivial-devices.txt    |   1 +
 drivers/iio/Kconfig                                |   1 +
 drivers/iio/Makefile                               |   1 +
 drivers/iio/chemical/Makefile                      |   6 +
 drivers/iio/chemical/vz89x.c                       | 236 +++++++++++++++++++++
 6 files changed, 275 insertions(+)
 create mode 100644 Documentation/ABI/testing/sysfs-bus-iio-chemical-vz89x
 create mode 100644 drivers/iio/chemical/Makefile
 create mode 100644 drivers/iio/chemical/vz89x.c

diff --git a/Documentation/ABI/testing/sysfs-bus-iio-chemical-vz89x b/Documentation/ABI/testing/sysfs-bus-iio-chemical-vz89x
new file mode 100644
index 0000000..74f2a35
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-bus-iio-chemical-vz89x
@@ -0,0 +1,30 @@
+What:		/sys/bus/iio/devices/iio:deviceX/in_concentration_CO2_raw
+Date:		September 2015
+KernelVersion:	4.3
+Contact:	Matt Ranostay <mranostay@gmail.com>
+Description:
+		Get the unscaled, and no offset applied CO2 gas percentage
+		value.
+
+What:		/sys/bus/iio/devices/iio:deviceX/in_concentration_VOC_short_raw
+Date:		September 2015
+KernelVersion:	4.3
+Contact:	Matt Ranostay <mranostay@gmail.com>
+Description:
+		Get the raw calibration VOC value from the sensor.
+		This value has little application outside of calibration.
+
+What:		/sys/bus/iio/devices/iio:deviceX/in_concentration_tVOC_raw
+Date:		September 2015
+KernelVersion:	4.3
+Contact:	Matt Ranostay <mranostay@gmail.com>
+Description:
+		Get the unscaled, and no offset applied total VOC gas
+		percentage value.
+
+What:		/sys/bus/iio/devices/iio:deviceX/in_resistance_raw
+Date:		September 2015
+KernelVersion:	4.3
+Contact:	Matt Ranostay <mranostay@gmail.com>
+Description:
+		Get the unscaled sensor resistance value.
diff --git a/Documentation/devicetree/bindings/i2c/trivial-devices.txt b/Documentation/devicetree/bindings/i2c/trivial-devices.txt
index d77d412..a550216 100644
--- a/Documentation/devicetree/bindings/i2c/trivial-devices.txt
+++ b/Documentation/devicetree/bindings/i2c/trivial-devices.txt
@@ -88,6 +88,7 @@ ricoh,rs5c372b		I2C bus SERIAL INTERFACE REAL-TIME CLOCK IC
 ricoh,rv5c386		I2C bus SERIAL INTERFACE REAL-TIME CLOCK IC
 ricoh,rv5c387a		I2C bus SERIAL INTERFACE REAL-TIME CLOCK IC
 samsung,24ad0xd1	S524AD0XF1 (128K/256K-bit Serial EEPROM for Low Power)
+sgx,vz89x		SGX Sensortech VZ89X Sensors
 sii,s35390a		2-wire CMOS real-time clock
 skyworks,sky81452	Skyworks SKY81452: Six-Channel White LED Driver with Touch Panel Bias Supply
 st-micro,24c256		i2c serial eeprom  (24cxx)
diff --git a/drivers/iio/Kconfig b/drivers/iio/Kconfig
index 4011eff..9664e9c 100644
--- a/drivers/iio/Kconfig
+++ b/drivers/iio/Kconfig
@@ -61,6 +61,7 @@ config IIO_CONSUMERS_PER_TRIGGER
 source "drivers/iio/accel/Kconfig"
 source "drivers/iio/adc/Kconfig"
 source "drivers/iio/amplifiers/Kconfig"
+source "drivers/iio/chemical/Kconfig"
 source "drivers/iio/common/Kconfig"
 source "drivers/iio/dac/Kconfig"
 source "drivers/iio/frequency/Kconfig"
diff --git a/drivers/iio/Makefile b/drivers/iio/Makefile
index 698afc2..2288684 100644
--- a/drivers/iio/Makefile
+++ b/drivers/iio/Makefile
@@ -14,6 +14,7 @@ obj-$(CONFIG_IIO_KFIFO_BUF) += kfifo_buf.o
 obj-y += accel/
 obj-y += adc/
 obj-y += amplifiers/
+obj-y += chemical/
 obj-y += common/
 obj-y += dac/
 obj-y += gyro/
diff --git a/drivers/iio/chemical/Makefile b/drivers/iio/chemical/Makefile
new file mode 100644
index 0000000..7292f2d
--- /dev/null
+++ b/drivers/iio/chemical/Makefile
@@ -0,0 +1,6 @@
+#
+# Makefile for IIO chemical sensors
+#
+
+# When adding new entries keep the list in alphabetical order
+obj-$(CONFIG_VZ89X)		+= vz89x.o
diff --git a/drivers/iio/chemical/vz89x.c b/drivers/iio/chemical/vz89x.c
new file mode 100644
index 0000000..ac381cc
--- /dev/null
+++ b/drivers/iio/chemical/vz89x.c
@@ -0,0 +1,236 @@
+/*
+ * vz89x.c - Support for SGX Sensortech MiCS VZ89X VOC sensors
+ *
+ * Copyright (C) 2015 Matt Ranostay <mranostay@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/init.h>
+#include <linux/i2c.h>
+
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+
+#define VZ89X_REG_MEASUREMENT		0x09
+#define VZ89X_REG_MEASUREMENT_SIZE	6
+
+#define VZ89X_VOC_CO2_IDX		0
+#define VZ89X_VOC_SHORT_IDX		1
+#define VZ89X_VOC_TVOC_IDX		2
+#define VZ89X_VOC_RESISTANCE_IDX	3
+
+struct vz89x_data {
+	struct i2c_client *client;
+	struct mutex lock;
+	unsigned long last_update;
+
+	u8 buffer[VZ89X_REG_MEASUREMENT_SIZE];
+};
+
+static const struct iio_chan_spec vz89x_channels[] = {
+	{
+		.type = IIO_CONCENTRATION,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_OFFSET) |
+			BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
+		.address = VZ89X_VOC_CO2_IDX,
+		.extend_name = "CO2",
+	},
+	{
+		.type = IIO_CONCENTRATION,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+		.address = VZ89X_VOC_SHORT_IDX,
+		.extend_name = "VOC_short",
+	},
+	{
+		.type = IIO_CONCENTRATION,
+		.info_mask_separate =
+			BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
+		.address = VZ89X_VOC_TVOC_IDX,
+		.extend_name = "tVOC",
+	},
+	{
+		.type = IIO_RESISTANCE,
+		.info_mask_separate =
+			BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
+		.address = VZ89X_VOC_RESISTANCE_IDX,
+	},
+};
+
+static int vz89x_get_measurement(struct vz89x_data *data)
+{
+	int ret;
+	int i;
+
+	/* sensor can only be polled once a second max per datasheet */
+	if (!time_after(jiffies, data->last_update + HZ))
+		return 0;
+
+	ret = i2c_smbus_write_word_data(data->client,
+					VZ89X_REG_MEASUREMENT, 0);
+	if (ret < 0)
+		return ret;
+
+	for (i = 0; i < VZ89X_REG_MEASUREMENT_SIZE; i++) {
+		ret = i2c_smbus_read_byte(data->client);
+		if (ret < 0)
+			return ret;
+		data->buffer[i] = ret;
+	}
+
+	data->last_update = jiffies;
+
+	return 0;
+}
+
+static int vz89x_get_resistance_reading(struct vz89x_data *data)
+{
+	u8 *buf = &data->buffer[VZ89X_VOC_TVOC_IDX];
+
+	return buf[0] | ((u16)buf[1] << 8) | ((u32)buf[2] << 16);
+}
+
+static int vz89x_get_channel_scale(struct iio_chan_spec const *chan,
+				   int *val, int *val2)
+{
+	switch (chan->address) {
+	case VZ89X_VOC_CO2_IDX:
+		*val = 1600;
+		*val2 = 229;
+		return IIO_VAL_FRACTIONAL;
+	case VZ89X_VOC_TVOC_IDX:
+		*val = 1000;
+		*val2 = 229;
+		return IIO_VAL_FRACTIONAL;
+	}
+
+	return -EINVAL;
+}
+
+static int vz89x_read_raw(struct iio_dev *indio_dev,
+			  struct iio_chan_spec const *chan, int *val,
+			  int *val2, long mask)
+{
+	struct vz89x_data *data = iio_priv(indio_dev);
+	int ret = -EINVAL;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		mutex_lock(&data->lock);
+		ret = vz89x_get_measurement(data);
+		mutex_unlock(&data->lock);
+
+		if (ret)
+			return ret;
+
+		switch (chan->address) {
+		case VZ89X_VOC_CO2_IDX:
+			*val = 0;
+			*val2 = data->buffer[chan->address] - 13;
+			return IIO_VAL_INT_PLUS_MICRO;
+		case VZ89X_VOC_SHORT_IDX:
+			*val = data->buffer[chan->address] - 13;
+			return IIO_VAL_INT;
+		case VZ89X_VOC_TVOC_IDX:
+			*val = 0;
+			*val2 = data->buffer[chan->address] - 13;
+			return IIO_VAL_INT_PLUS_NANO;
+		case VZ89X_VOC_RESISTANCE_IDX:
+			*val = vz89x_get_resistance_reading(data);
+			return IIO_VAL_INT;
+		default:
+			return -EINVAL;
+		}
+		break;
+	case IIO_CHAN_INFO_SCALE:
+		switch (chan->type) {
+		case IIO_RESISTANCE:
+			*val = 10;
+			return IIO_VAL_INT;
+		case IIO_CONCENTRATION:
+			return vz89x_get_channel_scale(chan, val, val2);
+		default:
+			return -EINVAL;
+		}
+		break;
+	case IIO_CHAN_INFO_OFFSET:
+		*val = 0;
+		*val2 = 400;
+		return IIO_VAL_INT_PLUS_MICRO;
+	}
+
+	return ret;
+}
+
+static const struct iio_info vz89x_info = {
+	.driver_module	= THIS_MODULE,
+	.read_raw	= vz89x_read_raw,
+};
+
+static int vz89x_probe(struct i2c_client *client,
+		       const struct i2c_device_id *id)
+{
+	struct iio_dev *indio_dev;
+	struct vz89x_data *data;
+
+	if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_WORD_DATA |
+				     I2C_FUNC_SMBUS_BYTE))
+		return -ENODEV;
+
+	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	data = iio_priv(indio_dev);
+	i2c_set_clientdata(client, indio_dev);
+	data->client = client;
+	data->last_update = jiffies - HZ;
+	mutex_init(&data->lock);
+
+	indio_dev->dev.parent = &client->dev;
+	indio_dev->info = &vz89x_info,
+	indio_dev->name = dev_name(&client->dev);
+	indio_dev->modes = INDIO_DIRECT_MODE;
+
+	indio_dev->channels = vz89x_channels;
+	indio_dev->num_channels = ARRAY_SIZE(vz89x_channels);
+
+	return devm_iio_device_register(&client->dev, indio_dev);
+}
+
+static const struct i2c_device_id vz89x_id[] = {
+	{ "vz89x", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, vz89x_id);
+
+static const struct of_device_id vz89x_dt_ids[] = {
+	{ .compatible = "sgx,vz89x" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, vz89x_dt_ids);
+
+static struct i2c_driver vz89x_driver = {
+	.driver = {
+		.name	= "vz89x",
+		.of_match_table = of_match_ptr(vz89x_dt_ids),
+	},
+	.probe = vz89x_probe,
+	.id_table = vz89x_id,
+};
+module_i2c_driver(vz89x_driver);
+
+MODULE_AUTHOR("Matt Ranostay <mranostay@gmail.com>");
+MODULE_DESCRIPTION("SGX Sensortech MiCS VZ89X VOC sensors");
+MODULE_LICENSE("GPL v2");
-- 
1.9.1

Re: [RFC v2 4/4] iio: chemical: add SGX VZ89x VOC sensor support

[Matt Ranostay]

Also one thing to note here is calculation is ((value - 13) * scale))
+ offset versus the normal (value + offset) * scale.. Not sure the
best way to handle this possibly could be..

Thanks,

Matt

On Sun, Sep 6, 2015 at 8:13 PM, George McCollister
<george.mccollister-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
>
>
> On Sun, Sep 6, 2015 at 9:39 PM, Matt Ranostay <mranostay-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
>>
>> Add support for VZ89X sensors VOC and CO2 reporting channels in
>> percentage which can be converted to part per million.
>>
>> Signed-off-by: Matt Ranostay <mranostay-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
>> ---
>>  .../ABI/testing/sysfs-bus-iio-chemical-vz89x       |  30 +++
>>  .../devicetree/bindings/i2c/trivial-devices.txt    |   1 +
>>  drivers/iio/Kconfig                                |   1 +
>>  drivers/iio/Makefile                               |   1 +
>>  drivers/iio/chemical/Makefile                      |   6 +
>>  drivers/iio/chemical/vz89x.c                       | 236
>> +++++++++++++++++++++
>>  6 files changed, 275 insertions(+)
>>  create mode 100644 Documentation/ABI/testing/sysfs-bus-iio-chemical-vz89x
>>  create mode 100644 drivers/iio/chemical/Makefile
>>  create mode 100644 drivers/iio/chemical/vz89x.c
>>
>> diff --git a/Documentation/ABI/testing/sysfs-bus-iio-chemical-vz89x
>> b/Documentation/ABI/testing/sysfs-bus-iio-chemical-vz89x
>> new file mode 100644
>> index 0000000..74f2a35
>> --- /dev/null
>> +++ b/Documentation/ABI/testing/sysfs-bus-iio-chemical-vz89x
>> @@ -0,0 +1,30 @@
>> +What:          /sys/bus/iio/devices/iio:deviceX/in_concentration_CO2_raw
>> +Date:          September 2015
>> +KernelVersion: 4.3
>> +Contact:       Matt Ranostay <mranostay-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
>> +Description:
>> +               Get the unscaled, and no offset applied CO2 gas percentage
>> +               value.
>> +
>> +What:
>> /sys/bus/iio/devices/iio:deviceX/in_concentration_VOC_short_raw
>> +Date:          September 2015
>> +KernelVersion: 4.3
>> +Contact:       Matt Ranostay <mranostay-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
>> +Description:
>> +               Get the raw calibration VOC value from the sensor.
>> +               This value has little application outside of calibration.
>> +
>> +What:          /sys/bus/iio/devices/iio:deviceX/in_concentration_tVOC_raw
>> +Date:          September 2015
>> +KernelVersion: 4.3
>> +Contact:       Matt Ranostay <mranostay-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
>> +Description:
>> +               Get the unscaled, and no offset applied total VOC gas
>> +               percentage value.
>> +
>> +What:          /sys/bus/iio/devices/iio:deviceX/in_resistance_raw
>> +Date:          September 2015
>> +KernelVersion: 4.3
>> +Contact:       Matt Ranostay <mranostay-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
>> +Description:
>> +               Get the unscaled sensor resistance value.
>> diff --git a/Documentation/devicetree/bindings/i2c/trivial-devices.txt
>> b/Documentation/devicetree/bindings/i2c/trivial-devices.txt
>> index d77d412..a550216 100644
>> --- a/Documentation/devicetree/bindings/i2c/trivial-devices.txt
>> +++ b/Documentation/devicetree/bindings/i2c/trivial-devices.txt
>> @@ -88,6 +88,7 @@ ricoh,rs5c372b                I2C bus SERIAL INTERFACE
>> REAL-TIME CLOCK IC
>>  ricoh,rv5c386          I2C bus SERIAL INTERFACE REAL-TIME CLOCK IC
>>  ricoh,rv5c387a         I2C bus SERIAL INTERFACE REAL-TIME CLOCK IC
>>  samsung,24ad0xd1       S524AD0XF1 (128K/256K-bit Serial EEPROM for Low
>> Power)
>> +sgx,vz89x              SGX Sensortech VZ89X Sensors
>>  sii,s35390a            2-wire CMOS real-time clock
>>  skyworks,sky81452      Skyworks SKY81452: Six-Channel White LED Driver
>> with Touch Panel Bias Supply
>>  st-micro,24c256                i2c serial eeprom  (24cxx)
>> diff --git a/drivers/iio/Kconfig b/drivers/iio/Kconfig
>> index 4011eff..9664e9c 100644
>> --- a/drivers/iio/Kconfig
>> +++ b/drivers/iio/Kconfig
>> @@ -61,6 +61,7 @@ config IIO_CONSUMERS_PER_TRIGGER
>>  source "drivers/iio/accel/Kconfig"
>>  source "drivers/iio/adc/Kconfig"
>>  source "drivers/iio/amplifiers/Kconfig"
>> +source "drivers/iio/chemical/Kconfig"
>>  source "drivers/iio/common/Kconfig"
>>  source "drivers/iio/dac/Kconfig"
>>  source "drivers/iio/frequency/Kconfig"
>> diff --git a/drivers/iio/Makefile b/drivers/iio/Makefile
>> index 698afc2..2288684 100644
>> --- a/drivers/iio/Makefile
>> +++ b/drivers/iio/Makefile
>> @@ -14,6 +14,7 @@ obj-$(CONFIG_IIO_KFIFO_BUF) += kfifo_buf.o
>>  obj-y += accel/
>>  obj-y += adc/
>>  obj-y += amplifiers/
>> +obj-y += chemical/
>>  obj-y += common/
>>  obj-y += dac/
>>  obj-y += gyro/
>> diff --git a/drivers/iio/chemical/Makefile b/drivers/iio/chemical/Makefile
>> new file mode 100644
>> index 0000000..7292f2d
>> --- /dev/null
>> +++ b/drivers/iio/chemical/Makefile
>> @@ -0,0 +1,6 @@
>> +#
>> +# Makefile for IIO chemical sensors
>> +#
>> +
>> +# When adding new entries keep the list in alphabetical order
>> +obj-$(CONFIG_VZ89X)            += vz89x.o
>> diff --git a/drivers/iio/chemical/vz89x.c b/drivers/iio/chemical/vz89x.c
>> new file mode 100644
>> index 0000000..ac381cc
>> --- /dev/null
>> +++ b/drivers/iio/chemical/vz89x.c
>> @@ -0,0 +1,236 @@
>> +/*
>> + * vz89x.c - Support for SGX Sensortech MiCS VZ89X VOC sensors
>> + *
>> + * Copyright (C) 2015 Matt Ranostay <mranostay-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
>> + *
>> + * This program is free software; you can redistribute it and/or modify
>> + * it under the terms of the GNU General Public License as published by
>> + * the Free Software Foundation; either version 2 of the License, or
>> + * (at your option) any later version.
>> + *
>> + * This program is distributed in the hope that it will be useful,
>> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
>> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
>> + * GNU General Public License for more details.
>> + *
>> + */
>> +
>> +#include <linux/module.h>
>> +#include <linux/mutex.h>
>> +#include <linux/init.h>
>> +#include <linux/i2c.h>
>> +
>> +#include <linux/iio/iio.h>
>> +#include <linux/iio/sysfs.h>
>> +
>> +#define VZ89X_REG_MEASUREMENT          0x09
>> +#define VZ89X_REG_MEASUREMENT_SIZE     6
>> +
>> +#define VZ89X_VOC_CO2_IDX              0
>> +#define VZ89X_VOC_SHORT_IDX            1
>> +#define VZ89X_VOC_TVOC_IDX             2
>> +#define VZ89X_VOC_RESISTANCE_IDX       3
>> +
>> +struct vz89x_data {
>> +       struct i2c_client *client;
>> +       struct mutex lock;
>> +       unsigned long last_update;
>> +
>> +       u8 buffer[VZ89X_REG_MEASUREMENT_SIZE];
>> +};
>> +
>> +static const struct iio_chan_spec vz89x_channels[] = {
>> +       {
>> +               .type = IIO_CONCENTRATION,
>> +               .info_mask_separate = BIT(IIO_CHAN_INFO_OFFSET) |
>> +                       BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
>> +               .address = VZ89X_VOC_CO2_IDX,
>> +               .extend_name = "CO2",
>> +       },
>> +       {
>> +               .type = IIO_CONCENTRATION,
>> +               .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
>> +               .address = VZ89X_VOC_SHORT_IDX,
>> +               .extend_name = "VOC_short",
>> +       },
>> +       {
>> +               .type = IIO_CONCENTRATION,
>> +               .info_mask_separate =
>> +                       BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
>> +               .address = VZ89X_VOC_TVOC_IDX,
>> +               .extend_name = "tVOC",
>> +       },
>> +       {
>> +               .type = IIO_RESISTANCE,
>> +               .info_mask_separate =
>> +                       BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
>> +               .address = VZ89X_VOC_RESISTANCE_IDX,
>> +       },
>> +};
>> +
>> +static int vz89x_get_measurement(struct vz89x_data *data)
>> +{
>> +       int ret;
>> +       int i;
>> +
>> +       /* sensor can only be polled once a second max per datasheet */
>> +       if (!time_after(jiffies, data->last_update + HZ))
>> +               return 0;
>> +
>> +       ret = i2c_smbus_write_word_data(data->client,
>> +                                       VZ89X_REG_MEASUREMENT, 0);
>> +       if (ret < 0)
>> +               return ret;
>> +
>> +       for (i = 0; i < VZ89X_REG_MEASUREMENT_SIZE; i++) {
>> +               ret = i2c_smbus_read_byte(data->client);
>> +               if (ret < 0)
>> +                       return ret;
>> +               data->buffer[i] = ret;
>> +       }
>> +
>> +       data->last_update = jiffies;
>> +
>> +       return 0;
>> +}
>> +
>> +static int vz89x_get_resistance_reading(struct vz89x_data *data)
>> +{
>> +       u8 *buf = &data->buffer[VZ89X_VOC_TVOC_IDX];
>> +
>> +       return buf[0] | ((u16)buf[1] << 8) | ((u32)buf[2] << 16);
>> +}
>> +
>> +static int vz89x_get_channel_scale(struct iio_chan_spec const *chan,
>> +                                  int *val, int *val2)
>> +{
>> +       switch (chan->address) {
>> +       case VZ89X_VOC_CO2_IDX:
>> +               *val = 1600;
>> +               *val2 = 229;
>> +               return IIO_VAL_FRACTIONAL;
>> +       case VZ89X_VOC_TVOC_IDX:
>> +               *val = 1000;
>> +               *val2 = 229;
>> +               return IIO_VAL_FRACTIONAL;
>> +       }
>> +
>> +       return -EINVAL;
>> +}
>> +
>> +static int vz89x_read_raw(struct iio_dev *indio_dev,
>> +                         struct iio_chan_spec const *chan, int *val,
>> +                         int *val2, long mask)
>> +{
>> +       struct vz89x_data *data = iio_priv(indio_dev);
>> +       int ret = -EINVAL;
>> +
>> +       switch (mask) {
>> +       case IIO_CHAN_INFO_RAW:
>> +               mutex_lock(&data->lock);
>> +               ret = vz89x_get_measurement(data);
>> +               mutex_unlock(&data->lock);
>> +
>> +               if (ret)
>> +                       return ret;
>> +
>> +               switch (chan->address) {
>> +               case VZ89X_VOC_CO2_IDX:
>> +                       *val = 0;
>> +                       *val2 = data->buffer[chan->address] - 13;
>
> Magic numbers are unlucky.
>
>>
>> +                       return IIO_VAL_INT_PLUS_MICRO;
>> +               case VZ89X_VOC_SHORT_IDX:
>> +                       *val = data->buffer[chan->address] - 13;
>> +                       return IIO_VAL_INT;
>> +               case VZ89X_VOC_TVOC_IDX:
>> +                       *val = 0;
>> +                       *val2 = data->buffer[chan->address] - 13;
>> +                       return IIO_VAL_INT_PLUS_NANO;
>> +               case VZ89X_VOC_RESISTANCE_IDX:
>> +                       *val = vz89x_get_resistance_reading(data);
>> +                       return IIO_VAL_INT;
>> +               default:
>> +                       return -EINVAL;
>> +               }
>> +               break;
>> +       case IIO_CHAN_INFO_SCALE:
>> +               switch (chan->type) {
>> +               case IIO_RESISTANCE:
>> +                       *val = 10;
>> +                       return IIO_VAL_INT;
>> +               case IIO_CONCENTRATION:
>> +                       return vz89x_get_channel_scale(chan, val, val2);
>> +               default:
>> +                       return -EINVAL;
>> +               }
>> +               break;
>> +       case IIO_CHAN_INFO_OFFSET:
>> +               *val = 0;
>> +               *val2 = 400;
>> +               return IIO_VAL_INT_PLUS_MICRO;
>> +       }
>> +
>> +       return ret;
>> +}
>> +
>> +static const struct iio_info vz89x_info = {
>> +       .driver_module  = THIS_MODULE,
>> +       .read_raw       = vz89x_read_raw,
>> +};
>> +
>> +static int vz89x_probe(struct i2c_client *client,
>> +                      const struct i2c_device_id *id)
>> +{
>> +       struct iio_dev *indio_dev;
>> +       struct vz89x_data *data;
>> +
>> +       if (!i2c_check_functionality(client->adapter,
>> I2C_FUNC_SMBUS_WORD_DATA |
>> +                                    I2C_FUNC_SMBUS_BYTE))
>> +               return -ENODEV;
>> +
>> +       indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
>> +       if (!indio_dev)
>> +               return -ENOMEM;
>> +
>> +       data = iio_priv(indio_dev);
>> +       i2c_set_clientdata(client, indio_dev);
>> +       data->client = client;
>> +       data->last_update = jiffies - HZ;
>> +       mutex_init(&data->lock);
>> +
>> +       indio_dev->dev.parent = &client->dev;
>> +       indio_dev->info = &vz89x_info,
>> +       indio_dev->name = dev_name(&client->dev);
>> +       indio_dev->modes = INDIO_DIRECT_MODE;
>> +
>> +       indio_dev->channels = vz89x_channels;
>> +       indio_dev->num_channels = ARRAY_SIZE(vz89x_channels);
>> +
>> +       return devm_iio_device_register(&client->dev, indio_dev);
>> +}
>> +
>> +static const struct i2c_device_id vz89x_id[] = {
>> +       { "vz89x", 0 },
>> +       { }
>> +};
>> +MODULE_DEVICE_TABLE(i2c, vz89x_id);
>> +
>> +static const struct of_device_id vz89x_dt_ids[] = {
>> +       { .compatible = "sgx,vz89x" },
>> +       { }
>> +};
>> +MODULE_DEVICE_TABLE(of, vz89x_dt_ids);
>> +
>> +static struct i2c_driver vz89x_driver = {
>> +       .driver = {
>> +               .name   = "vz89x",
>> +               .of_match_table = of_match_ptr(vz89x_dt_ids),
>> +       },
>> +       .probe = vz89x_probe,
>> +       .id_table = vz89x_id,
>> +};
>> +module_i2c_driver(vz89x_driver);
>> +
>> +MODULE_AUTHOR("Matt Ranostay <mranostay-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>");
>> +MODULE_DESCRIPTION("SGX Sensortech MiCS VZ89X VOC sensors");
>> +MODULE_LICENSE("GPL v2");
>> --
>> 1.9.1
>>
>> --
>> To unsubscribe from this list: send the line "unsubscribe devicetree" in
>> the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>
>

Re: [RFC v2 4/4] iio: chemical: add SGX VZ89x VOC sensor support

[Matt Ranostay]

Thinking this over do we needed a IIO_CHAN_INFO_PROCESSED_OFFSET to
signal that it needs to be after the (value - offset) * scale
calculation?

Thanks,

Matt

On Sun, Sep 6, 2015 at 9:20 PM, Matt Ranostay <mranostay-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
> Also one thing to note here is calculation is ((value - 13) * scale))
> + offset versus the normal (value + offset) * scale.. Not sure the
> best way to handle this possibly could be..
>
> Thanks,
>
> Matt
>
> On Sun, Sep 6, 2015 at 8:13 PM, George McCollister
> <george.mccollister-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
>>
>>
>> On Sun, Sep 6, 2015 at 9:39 PM, Matt Ranostay <mranostay-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
>>>
>>> Add support for VZ89X sensors VOC and CO2 reporting channels in
>>> percentage which can be converted to part per million.
>>>
>>> Signed-off-by: Matt Ranostay <mranostay-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
>>> ---
>>>  .../ABI/testing/sysfs-bus-iio-chemical-vz89x       |  30 +++
>>>  .../devicetree/bindings/i2c/trivial-devices.txt    |   1 +
>>>  drivers/iio/Kconfig                                |   1 +
>>>  drivers/iio/Makefile                               |   1 +
>>>  drivers/iio/chemical/Makefile                      |   6 +
>>>  drivers/iio/chemical/vz89x.c                       | 236
>>> +++++++++++++++++++++
>>>  6 files changed, 275 insertions(+)
>>>  create mode 100644 Documentation/ABI/testing/sysfs-bus-iio-chemical-vz89x
>>>  create mode 100644 drivers/iio/chemical/Makefile
>>>  create mode 100644 drivers/iio/chemical/vz89x.c
>>>
>>> diff --git a/Documentation/ABI/testing/sysfs-bus-iio-chemical-vz89x
>>> b/Documentation/ABI/testing/sysfs-bus-iio-chemical-vz89x
>>> new file mode 100644
>>> index 0000000..74f2a35
>>> --- /dev/null
>>> +++ b/Documentation/ABI/testing/sysfs-bus-iio-chemical-vz89x
>>> @@ -0,0 +1,30 @@
>>> +What:          /sys/bus/iio/devices/iio:deviceX/in_concentration_CO2_raw
>>> +Date:          September 2015
>>> +KernelVersion: 4.3
>>> +Contact:       Matt Ranostay <mranostay-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
>>> +Description:
>>> +               Get the unscaled, and no offset applied CO2 gas percentage
>>> +               value.
>>> +
>>> +What:
>>> /sys/bus/iio/devices/iio:deviceX/in_concentration_VOC_short_raw
>>> +Date:          September 2015
>>> +KernelVersion: 4.3
>>> +Contact:       Matt Ranostay <mranostay-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
>>> +Description:
>>> +               Get the raw calibration VOC value from the sensor.
>>> +               This value has little application outside of calibration.
>>> +
>>> +What:          /sys/bus/iio/devices/iio:deviceX/in_concentration_tVOC_raw
>>> +Date:          September 2015
>>> +KernelVersion: 4.3
>>> +Contact:       Matt Ranostay <mranostay-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
>>> +Description:
>>> +               Get the unscaled, and no offset applied total VOC gas
>>> +               percentage value.
>>> +
>>> +What:          /sys/bus/iio/devices/iio:deviceX/in_resistance_raw
>>> +Date:          September 2015
>>> +KernelVersion: 4.3
>>> +Contact:       Matt Ranostay <mranostay-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
>>> +Description:
>>> +               Get the unscaled sensor resistance value.
>>> diff --git a/Documentation/devicetree/bindings/i2c/trivial-devices.txt
>>> b/Documentation/devicetree/bindings/i2c/trivial-devices.txt
>>> index d77d412..a550216 100644
>>> --- a/Documentation/devicetree/bindings/i2c/trivial-devices.txt
>>> +++ b/Documentation/devicetree/bindings/i2c/trivial-devices.txt
>>> @@ -88,6 +88,7 @@ ricoh,rs5c372b                I2C bus SERIAL INTERFACE
>>> REAL-TIME CLOCK IC
>>>  ricoh,rv5c386          I2C bus SERIAL INTERFACE REAL-TIME CLOCK IC
>>>  ricoh,rv5c387a         I2C bus SERIAL INTERFACE REAL-TIME CLOCK IC
>>>  samsung,24ad0xd1       S524AD0XF1 (128K/256K-bit Serial EEPROM for Low
>>> Power)
>>> +sgx,vz89x              SGX Sensortech VZ89X Sensors
>>>  sii,s35390a            2-wire CMOS real-time clock
>>>  skyworks,sky81452      Skyworks SKY81452: Six-Channel White LED Driver
>>> with Touch Panel Bias Supply
>>>  st-micro,24c256                i2c serial eeprom  (24cxx)
>>> diff --git a/drivers/iio/Kconfig b/drivers/iio/Kconfig
>>> index 4011eff..9664e9c 100644
>>> --- a/drivers/iio/Kconfig
>>> +++ b/drivers/iio/Kconfig
>>> @@ -61,6 +61,7 @@ config IIO_CONSUMERS_PER_TRIGGER
>>>  source "drivers/iio/accel/Kconfig"
>>>  source "drivers/iio/adc/Kconfig"
>>>  source "drivers/iio/amplifiers/Kconfig"
>>> +source "drivers/iio/chemical/Kconfig"
>>>  source "drivers/iio/common/Kconfig"
>>>  source "drivers/iio/dac/Kconfig"
>>>  source "drivers/iio/frequency/Kconfig"
>>> diff --git a/drivers/iio/Makefile b/drivers/iio/Makefile
>>> index 698afc2..2288684 100644
>>> --- a/drivers/iio/Makefile
>>> +++ b/drivers/iio/Makefile
>>> @@ -14,6 +14,7 @@ obj-$(CONFIG_IIO_KFIFO_BUF) += kfifo_buf.o
>>>  obj-y += accel/
>>>  obj-y += adc/
>>>  obj-y += amplifiers/
>>> +obj-y += chemical/
>>>  obj-y += common/
>>>  obj-y += dac/
>>>  obj-y += gyro/
>>> diff --git a/drivers/iio/chemical/Makefile b/drivers/iio/chemical/Makefile
>>> new file mode 100644
>>> index 0000000..7292f2d
>>> --- /dev/null
>>> +++ b/drivers/iio/chemical/Makefile
>>> @@ -0,0 +1,6 @@
>>> +#
>>> +# Makefile for IIO chemical sensors
>>> +#
>>> +
>>> +# When adding new entries keep the list in alphabetical order
>>> +obj-$(CONFIG_VZ89X)            += vz89x.o
>>> diff --git a/drivers/iio/chemical/vz89x.c b/drivers/iio/chemical/vz89x.c
>>> new file mode 100644
>>> index 0000000..ac381cc
>>> --- /dev/null
>>> +++ b/drivers/iio/chemical/vz89x.c
>>> @@ -0,0 +1,236 @@
>>> +/*
>>> + * vz89x.c - Support for SGX Sensortech MiCS VZ89X VOC sensors
>>> + *
>>> + * Copyright (C) 2015 Matt Ranostay <mranostay-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
>>> + *
>>> + * This program is free software; you can redistribute it and/or modify
>>> + * it under the terms of the GNU General Public License as published by
>>> + * the Free Software Foundation; either version 2 of the License, or
>>> + * (at your option) any later version.
>>> + *
>>> + * This program is distributed in the hope that it will be useful,
>>> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
>>> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
>>> + * GNU General Public License for more details.
>>> + *
>>> + */
>>> +
>>> +#include <linux/module.h>
>>> +#include <linux/mutex.h>
>>> +#include <linux/init.h>
>>> +#include <linux/i2c.h>
>>> +
>>> +#include <linux/iio/iio.h>
>>> +#include <linux/iio/sysfs.h>
>>> +
>>> +#define VZ89X_REG_MEASUREMENT          0x09
>>> +#define VZ89X_REG_MEASUREMENT_SIZE     6
>>> +
>>> +#define VZ89X_VOC_CO2_IDX              0
>>> +#define VZ89X_VOC_SHORT_IDX            1
>>> +#define VZ89X_VOC_TVOC_IDX             2
>>> +#define VZ89X_VOC_RESISTANCE_IDX       3
>>> +
>>> +struct vz89x_data {
>>> +       struct i2c_client *client;
>>> +       struct mutex lock;
>>> +       unsigned long last_update;
>>> +
>>> +       u8 buffer[VZ89X_REG_MEASUREMENT_SIZE];
>>> +};
>>> +
>>> +static const struct iio_chan_spec vz89x_channels[] = {
>>> +       {
>>> +               .type = IIO_CONCENTRATION,
>>> +               .info_mask_separate = BIT(IIO_CHAN_INFO_OFFSET) |
>>> +                       BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
>>> +               .address = VZ89X_VOC_CO2_IDX,
>>> +               .extend_name = "CO2",
>>> +       },
>>> +       {
>>> +               .type = IIO_CONCENTRATION,
>>> +               .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
>>> +               .address = VZ89X_VOC_SHORT_IDX,
>>> +               .extend_name = "VOC_short",
>>> +       },
>>> +       {
>>> +               .type = IIO_CONCENTRATION,
>>> +               .info_mask_separate =
>>> +                       BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
>>> +               .address = VZ89X_VOC_TVOC_IDX,
>>> +               .extend_name = "tVOC",
>>> +       },
>>> +       {
>>> +               .type = IIO_RESISTANCE,
>>> +               .info_mask_separate =
>>> +                       BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
>>> +               .address = VZ89X_VOC_RESISTANCE_IDX,
>>> +       },
>>> +};
>>> +
>>> +static int vz89x_get_measurement(struct vz89x_data *data)
>>> +{
>>> +       int ret;
>>> +       int i;
>>> +
>>> +       /* sensor can only be polled once a second max per datasheet */
>>> +       if (!time_after(jiffies, data->last_update + HZ))
>>> +               return 0;
>>> +
>>> +       ret = i2c_smbus_write_word_data(data->client,
>>> +                                       VZ89X_REG_MEASUREMENT, 0);
>>> +       if (ret < 0)
>>> +               return ret;
>>> +
>>> +       for (i = 0; i < VZ89X_REG_MEASUREMENT_SIZE; i++) {
>>> +               ret = i2c_smbus_read_byte(data->client);
>>> +               if (ret < 0)
>>> +                       return ret;
>>> +               data->buffer[i] = ret;
>>> +       }
>>> +
>>> +       data->last_update = jiffies;
>>> +
>>> +       return 0;
>>> +}
>>> +
>>> +static int vz89x_get_resistance_reading(struct vz89x_data *data)
>>> +{
>>> +       u8 *buf = &data->buffer[VZ89X_VOC_TVOC_IDX];
>>> +
>>> +       return buf[0] | ((u16)buf[1] << 8) | ((u32)buf[2] << 16);
>>> +}
>>> +
>>> +static int vz89x_get_channel_scale(struct iio_chan_spec const *chan,
>>> +                                  int *val, int *val2)
>>> +{
>>> +       switch (chan->address) {
>>> +       case VZ89X_VOC_CO2_IDX:
>>> +               *val = 1600;
>>> +               *val2 = 229;
>>> +               return IIO_VAL_FRACTIONAL;
>>> +       case VZ89X_VOC_TVOC_IDX:
>>> +               *val = 1000;
>>> +               *val2 = 229;
>>> +               return IIO_VAL_FRACTIONAL;
>>> +       }
>>> +
>>> +       return -EINVAL;
>>> +}
>>> +
>>> +static int vz89x_read_raw(struct iio_dev *indio_dev,
>>> +                         struct iio_chan_spec const *chan, int *val,
>>> +                         int *val2, long mask)
>>> +{
>>> +       struct vz89x_data *data = iio_priv(indio_dev);
>>> +       int ret = -EINVAL;
>>> +
>>> +       switch (mask) {
>>> +       case IIO_CHAN_INFO_RAW:
>>> +               mutex_lock(&data->lock);
>>> +               ret = vz89x_get_measurement(data);
>>> +               mutex_unlock(&data->lock);
>>> +
>>> +               if (ret)
>>> +                       return ret;
>>> +
>>> +               switch (chan->address) {
>>> +               case VZ89X_VOC_CO2_IDX:
>>> +                       *val = 0;
>>> +                       *val2 = data->buffer[chan->address] - 13;
>>
>> Magic numbers are unlucky.
>>
>>>
>>> +                       return IIO_VAL_INT_PLUS_MICRO;
>>> +               case VZ89X_VOC_SHORT_IDX:
>>> +                       *val = data->buffer[chan->address] - 13;
>>> +                       return IIO_VAL_INT;
>>> +               case VZ89X_VOC_TVOC_IDX:
>>> +                       *val = 0;
>>> +                       *val2 = data->buffer[chan->address] - 13;
>>> +                       return IIO_VAL_INT_PLUS_NANO;
>>> +               case VZ89X_VOC_RESISTANCE_IDX:
>>> +                       *val = vz89x_get_resistance_reading(data);
>>> +                       return IIO_VAL_INT;
>>> +               default:
>>> +                       return -EINVAL;
>>> +               }
>>> +               break;
>>> +       case IIO_CHAN_INFO_SCALE:
>>> +               switch (chan->type) {
>>> +               case IIO_RESISTANCE:
>>> +                       *val = 10;
>>> +                       return IIO_VAL_INT;
>>> +               case IIO_CONCENTRATION:
>>> +                       return vz89x_get_channel_scale(chan, val, val2);
>>> +               default:
>>> +                       return -EINVAL;
>>> +               }
>>> +               break;
>>> +       case IIO_CHAN_INFO_OFFSET:
>>> +               *val = 0;
>>> +               *val2 = 400;
>>> +               return IIO_VAL_INT_PLUS_MICRO;
>>> +       }
>>> +
>>> +       return ret;
>>> +}
>>> +
>>> +static const struct iio_info vz89x_info = {
>>> +       .driver_module  = THIS_MODULE,
>>> +       .read_raw       = vz89x_read_raw,
>>> +};
>>> +
>>> +static int vz89x_probe(struct i2c_client *client,
>>> +                      const struct i2c_device_id *id)
>>> +{
>>> +       struct iio_dev *indio_dev;
>>> +       struct vz89x_data *data;
>>> +
>>> +       if (!i2c_check_functionality(client->adapter,
>>> I2C_FUNC_SMBUS_WORD_DATA |
>>> +                                    I2C_FUNC_SMBUS_BYTE))
>>> +               return -ENODEV;
>>> +
>>> +       indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
>>> +       if (!indio_dev)
>>> +               return -ENOMEM;
>>> +
>>> +       data = iio_priv(indio_dev);
>>> +       i2c_set_clientdata(client, indio_dev);
>>> +       data->client = client;
>>> +       data->last_update = jiffies - HZ;
>>> +       mutex_init(&data->lock);
>>> +
>>> +       indio_dev->dev.parent = &client->dev;
>>> +       indio_dev->info = &vz89x_info,
>>> +       indio_dev->name = dev_name(&client->dev);
>>> +       indio_dev->modes = INDIO_DIRECT_MODE;
>>> +
>>> +       indio_dev->channels = vz89x_channels;
>>> +       indio_dev->num_channels = ARRAY_SIZE(vz89x_channels);
>>> +
>>> +       return devm_iio_device_register(&client->dev, indio_dev);
>>> +}
>>> +
>>> +static const struct i2c_device_id vz89x_id[] = {
>>> +       { "vz89x", 0 },
>>> +       { }
>>> +};
>>> +MODULE_DEVICE_TABLE(i2c, vz89x_id);
>>> +
>>> +static const struct of_device_id vz89x_dt_ids[] = {
>>> +       { .compatible = "sgx,vz89x" },
>>> +       { }
>>> +};
>>> +MODULE_DEVICE_TABLE(of, vz89x_dt_ids);
>>> +
>>> +static struct i2c_driver vz89x_driver = {
>>> +       .driver = {
>>> +               .name   = "vz89x",
>>> +               .of_match_table = of_match_ptr(vz89x_dt_ids),
>>> +       },
>>> +       .probe = vz89x_probe,
>>> +       .id_table = vz89x_id,
>>> +};
>>> +module_i2c_driver(vz89x_driver);
>>> +
>>> +MODULE_AUTHOR("Matt Ranostay <mranostay-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>");
>>> +MODULE_DESCRIPTION("SGX Sensortech MiCS VZ89X VOC sensors");
>>> +MODULE_LICENSE("GPL v2");
>>> --
>>> 1.9.1
>>>
>>> --
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>>
>>
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Re: [RFC v2 4/4] iio: chemical: add SGX VZ89x VOC sensor support

[Lars-Peter Clausen]

On 09/07/2015 06:27 AM, Matt Ranostay wrote:
> Thinking this over do we needed a IIO_CHAN_INFO_PROCESSED_OFFSET to
> signal that it needs to be after the (value - offset) * scale
> calculation?

Well, value * scale + offset = (value + offset/scale) * scale. So just scale
your offset inversely to the scale.

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