Re: [RFC v1 4/4] iio: chemical: add SGX VZ89x VOC sensor support

From: Matt Ranostay
Date: Sat Sep 05 2015 - 18:18:08 EST

On Sat, Sep 5, 2015 at 9:14 AM, Jonathan Cameron <jic23@xxxxxxxxxx> wrote:
> On 05/09/15 06:53, Matt Ranostay wrote:
>> Add support for VZ89X sensors VOC and CO2 reporting channels in
>> ppm/ppb units.
>>
>> Signed-off-by: Matt Ranostay <mranostay@xxxxxxxxx>
> Few points inline. I'm either rather too sleepy or you don't actually
> store threadings in your cache during the read measurement function hence
> the driver will rather spectacularly not work right now :)
>
> Jonathan
>> ---
>> .../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 | 237 +++++++++++++++++++++
>> 5 files changed, 246 insertions(+)
>> create mode 100644 drivers/iio/chemical/Makefile
>> create mode 100644 drivers/iio/chemical/vz89x.c
>>
>> 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..a596a22
>> --- /dev/null
>> +++ b/drivers/iio/chemical/vz89x.c
>> @@ -0,0 +1,237 @@
>> +/*
>> + * 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_RESISTANCE_IDX 3
>> +
>> +struct vz89x_data {
>> + struct i2c_client *client;
>> + struct mutex lock;
>> + unsigned long last_update;
>> +
>> + u8 buffer[VZ89X_REG_MEASUREMENT_SIZE];
>
> Just a small point, but unless I'm missing something you forgot
> to actually copy any data into the buffer anywhere. Guess testing would
> make this obviously fairly quickly once you have the part :)
>
>> +};
>> +
>> +static const struct iio_chan_spec vz89x_channels[] = {
>> + {
>> + .type = IIO_CONCENTRATION,
>> + .channel2 = IIO_MOD_PPM,
>> + .modified = 1,
>> + .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) | BIT(IIO_CHAN_INFO_SCALE),
>> + .address = VZ89X_VOC_SHORT_IDX,
>> + .extend_name = "VOC_short",
>> + },
>> + {
>> + .type = IIO_CONCENTRATION,
>> + .channel2 = IIO_MOD_PPB,
>> + .modified = 1,
>> + .info_mask_separate =
>> + BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
>> + .address = VZ89X_VOC_TVOC_IDX,
>> + .extend_name = "tVOC",
>> + },
>> + {
> I think this is effectively a raw measurement of the signal used
> to derive the above values? I'm I reading the datasheet correctly
> about this? Not that it maters but might be nice to add a comment
> to that effect.

Ok.
>> + .type = IIO_RESISTANCE,
>> + .info_mask_separate =
>> + BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
>> + .address = VZ89X_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 -EBUSY? and pass it all the way up to userspace to let
> it know why no value was returned.
>> + 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;
> Store the result somewhere perhaps?

Oops missed the data->buffer[i] = ret :)

>> + }
>> +
>> + data->last_update = jiffies;
>> +
>> + return 0;
>> +}
>> +
>> +static int vz89x_get_resistance_reading(struct vz89x_data *data,
>> + struct iio_chan_spec const *chan)
>> +{
>> + u8 *buf = &data->buffer[chan->address];
>> +
>> + return buf[0] | ((u16)buf[1] << 8) | ((u16)buf[2] << 16);
>> +}
>> +
>> +static int vz89x_get_channel_scale(struct iio_chan_spec const *chan,
>> + int *val, int *val2)
>> +{
>> + int ret = -EINVAL;
>> +
>> + switch (chan->address) {
>> + case VZ89X_VOC_CO2_IDX:
>> + *val = 1600;
>> + *val2 = 229;
>> + ret = IIO_VAL_FRACTIONAL;
>> + break;
>> + case VZ89X_VOC_SHORT_IDX:
>> + *val = 0;
>> + ret = IIO_VAL_INT;
>> + break;
>> + case VZ89X_VOC_TVOC_IDX:
>> + *val = 1000;
>> + *val2 = 229;
>> + ret = IIO_VAL_FRACTIONAL;
>> + }
>> +
>> + return ret;
>> +}
>> +
>> +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);
>> +
>> + if (chan->type == IIO_RESISTANCE)
>> + *val = vz89x_get_resistance_reading(data, chan);
>> + else
>> + *val = data->buffer[chan->address] - 13;
>> +
>> + if (!ret)
>> + ret = IIO_VAL_INT;
>> +
>> + mutex_unlock(&data->lock);
>> + break;
>> + case IIO_CHAN_INFO_SCALE:
>> + switch (chan->type) {
>> + case IIO_RESISTANCE:
>> + *val = 10;
>> + ret = IIO_VAL_INT;
>> + break;
>> + case IIO_CONCENTRATION:
>> + ret = vz89x_get_channel_scale(chan, val, val2);
>> + break;
>> + default:
>> + ret = -EINVAL;
>> + }
>> + break;
>> + case IIO_CHAN_INFO_OFFSET:
>> + *val = 400;
>> + ret = IIO_VAL_INT;
>> + break;
>> + }
>> +
>> + 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");
>>
>
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