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

[Matt Ranostay <mranostay@gmail.com>]

On Sat, Sep 5, 2015 at 9:14 AM, Jonathan Cameron <jic23@kernel.org> 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@gmail.com>
> 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@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_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@gmail.com>");
>> +MODULE_DESCRIPTION("SGX Sensortech MiCS VZ89X VOC sensors");
>> +MODULE_LICENSE("GPL v2");
>>
>