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

[Peter Meerwald]

> Add support for VZ89X sensors VOC and CO2 reporting channels in
> ppm/ppb units.

comments below
link to datasheet?

> 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?

> +		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

> +}
> +
> +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

> +		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?

> +
> +		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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