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

From: Peter Meerwald
Date: Sat Sep 05 2015 - 04:11:33 EST


> >> Add support for VZ89X sensors VOC and CO2 reporting channels in
> >> ppm/ppb units.
> >
> > comments below
> > link to datasheet?
>
> I will post the links when I am not at the Oregon coast. Have no laptop atm...
>
> >
> >> Signed-off-by: Matt Ranostay <mranostay@xxxxxxxxx>
> >> ---
> >> .../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];
> >> +};
> >> +
> >> +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",
> >> + },
> >> + {
> >> + .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 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);
> >
> > could a block transfer be used?
>
> Yah from the data sheet on i2c it can only do byte reads after the
> "command write data of zero"... I'll know better I have this part in
> hand.... But from Arduino hippies it seems I have gotten weird sensors
> to work on this chipset....

and the transfer is at most once per second, so no big performance deal

>
> >> + if (ret < 0)
> >> + return 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];
> >
> > I think only VZ89X_RESISTANCE_IDX as chan->address makes sense here?
> >
> >> +
> >> + return buf[0] | ((u16)buf[1] << 8) | ((u16)buf[2] << 16);
> >
> > why cast to u16? no cast is neccessary
> Maybe but to be safe of compilers not getting the shift left values that could happen doesn't hurt

(u16)buf[2] << 16
u16 still makes no sense

> >
> >> +}
> >> +
> >> +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;
> >
> > return directly and save the break, no init of ret
>
> Old habits :)

agree, matter of taste; but in this case is saves somes lines

> >> + 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;
> >
> > default
> >
> >> + }
> >> +
> >> + 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);
> >
> > chan argument is not needed
> >
> >> + else
> >> + *val = data->buffer[chan->address] - 13;
> >
> > maybe have this block after checking ret, operating on invalid data isn't
> > well behaved :)
> > what is 13? could this be incorporated in _OFFSET?
> >
>
> Yeah if scale value wasn't calculated first... Need to ask them why 13.. I mean really

I always have to look is up as well: it is (value + offset) * scale

> >> +
> >> + 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");
> >
> > --
> >
> > Peter Meerwald
> > +43-664-2444418 (mobile)
> --
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--

Peter Meerwald
+43-664-2444418 (mobile)
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