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

From: Matt Ranostay
Date: Mon Sep 07 2015 - 00:28:08 EST

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@xxxxxxxxx> 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@xxxxxxxxx> wrote:
>>
>>
>> On Sun, Sep 6, 2015 at 9:39 PM, Matt Ranostay <mranostay@xxxxxxxxx> 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@xxxxxxxxx>
>>> ---
>>> .../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@xxxxxxxxx>
>>> +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@xxxxxxxxx>
>>> +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@xxxxxxxxx>
>>> +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@xxxxxxxxx>
>>> +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@xxxxxxxxx>
>>> + *
>>> + * 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@xxxxxxxxx>");
>>> +MODULE_DESCRIPTION("SGX Sensortech MiCS VZ89X VOC sensors");
>>> +MODULE_LICENSE("GPL v2");
>>> --
>>> 1.9.1
>>>
>>> --
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>>
>>
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