Re: [PATCH] iio: chemical: add AMS iAQ-core support

[Jonathan Cameron <jic23@kernel.org>]

On 01/12/15 03:46, Matt Ranostay wrote:
> Add support for AMS iAQ-core continuous and pulsed VOC sensors.
> 
> Signed-off-by: Matt Ranostay <mranostay@gmail.com>
The only real question that this raises for me is whether returning the
last good value is a good idea if the sensor isn't ready to take a new
one yet...

Otherwise a few bits and bobs inline.
> ---
>  .../devicetree/bindings/i2c/trivial-devices.txt    |   1 +
>  drivers/iio/chemical/Kconfig                       |   8 +
>  drivers/iio/chemical/Makefile                      |   1 +
>  drivers/iio/chemical/ams-iaq-core.c                | 190 +++++++++++++++++++++
>  4 files changed, 200 insertions(+)
>  create mode 100644 drivers/iio/chemical/ams-iaq-core.c
> 
> diff --git a/Documentation/devicetree/bindings/i2c/trivial-devices.txt b/Documentation/devicetree/bindings/i2c/trivial-devices.txt
> index c50cf13..f6fec95 100644
> --- a/Documentation/devicetree/bindings/i2c/trivial-devices.txt
> +++ b/Documentation/devicetree/bindings/i2c/trivial-devices.txt
> @@ -20,6 +20,7 @@ adi,adt7476		+/-1C TDM Extended Temp Range I.C
>  adi,adt7490		+/-1C TDM Extended Temp Range I.C
>  adi,adxl345		Three-Axis Digital Accelerometer
>  adi,adxl346		Three-Axis Digital Accelerometer (backward-compatibility value "adi,adxl345" must be listed too)
> +ams,iaq-core		AMS iAQ-Core VOC Sensor
>  at,24c08		i2c serial eeprom  (24cxx)
>  atmel,24c00		i2c serial eeprom  (24cxx)
>  atmel,24c01		i2c serial eeprom  (24cxx)
> diff --git a/drivers/iio/chemical/Kconfig b/drivers/iio/chemical/Kconfig
> index 3061b72..f16de61 100644
> --- a/drivers/iio/chemical/Kconfig
> +++ b/drivers/iio/chemical/Kconfig
> @@ -4,6 +4,14 @@
>  
>  menu "Chemical Sensors"
>  
> +config IAQCORE
> +	tristate "AMS iAQ-Core VOC sensors"
> +	depends on I2C
> +	help
> +	  Say Y here to build I2C interface support for the AMS
> +	  iAQ-Core Continuous/Pulsed VOC (Volatile Organic Compounds)
> +	  sensors
> +
>  config VZ89X
>  	tristate "SGX Sensortech MiCS VZ89X VOC sensor"
>  	depends on I2C
> diff --git a/drivers/iio/chemical/Makefile b/drivers/iio/chemical/Makefile
> index 7292f2d..167861f 100644
> --- a/drivers/iio/chemical/Makefile
> +++ b/drivers/iio/chemical/Makefile
> @@ -3,4 +3,5 @@
>  #
>  
>  # When adding new entries keep the list in alphabetical order
> +obj-$(CONFIG_IAQCORE)		+= ams-iaq-core.o
>  obj-$(CONFIG_VZ89X)		+= vz89x.o
> diff --git a/drivers/iio/chemical/ams-iaq-core.c b/drivers/iio/chemical/ams-iaq-core.c
> new file mode 100644
> index 0000000..db9aa39
> --- /dev/null
> +++ b/drivers/iio/chemical/ams-iaq-core.c
> @@ -0,0 +1,190 @@
> +/*
> + * ams-iaq-core.c - Support for AMS iAQ-Core 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>
> +
> +#define AMS_IAQCORE_DATA_SIZE		9
> +
> +#define AMS_IAQCORE_VOC_CO2_IDX		0
> +#define AMS_IAQCORE_VOC_RESISTANCE_IDX	1
> +#define AMS_IAQCORE_VOC_TVOC_IDX	2
> +
> +struct ams_iaqcore_reading {
> +	__be16 co2_ppm;
> +	u8 status;
> +	__be32 resistance;
> +	__be16 voc_ppb;
> +} __attribute__((__packed__));
> +
> +struct ams_iaqcore_data {
> +	struct i2c_client *client;
> +	struct mutex lock;
> +	unsigned long last_update;
> +
> +	struct ams_iaqcore_reading buffer;
> +};
> +
> +static const struct iio_chan_spec ams_iaqcore_channels[] = {
> +	{
> +		.type = IIO_CONCENTRATION,
> +		.channel2 = IIO_MOD_CO2,
> +		.modified = 1,
> +		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
No info at all on scaling etc?  ppm is mentioned on the
data sheet.
> +		.address = AMS_IAQCORE_VOC_CO2_IDX,
> +	},
> +	{
> +		.type = IIO_RESISTANCE,
> +		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
As I read the datahsheet this is in ohms anyway so
IIO_CHAN_INFO_PROCESSED is more appropriate.
> +		.address = AMS_IAQCORE_VOC_RESISTANCE_IDX,
> +	},
> +	{
> +		.type = IIO_CONCENTRATION,
> +		.channel2 = IIO_MOD_VOC,
> +		.modified = 1,
Again datasheet implies you can give this a scaling...
> +		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
> +		.address = AMS_IAQCORE_VOC_TVOC_IDX,
> +	},
> +};
> +
> +static int ams_iaqcore_read_measurement(struct ams_iaqcore_data *data)
> +{
> +	struct i2c_client *client = data->client;
> +	int ret;
> +
> +	struct i2c_msg msg[] = {
> +		{
> +			.addr = client->addr,
> +			.flags = client->flags | I2C_M_RD,
> +			.len = AMS_IAQCORE_DATA_SIZE,
> +			.buf = (char *) &data->buffer,
> +		},
Why have an array?  Just drop that and pass &msg into the i2c
transfer call.
> +	};
> +
> +	ret = i2c_transfer(client->adapter, msg, 1);
> +
> +	return (ret == AMS_IAQCORE_DATA_SIZE) ? 0 : ret;
> +}
> +
> +static int ams_iaqcore_get_measurement(struct ams_iaqcore_data *data)
> +{
> +	int ret;
> +
> +	/* sensor can only be polled once a second max per datasheet */
> +	if (!time_after(jiffies, data->last_update + HZ))
> +		return 0;
> +
> +	ret = ams_iaqcore_read_measurement(data);
> +	if (ret < 0)
> +		return ret;
> +
> +	data->last_update = jiffies;
> +
> +	return 0;
> +}
> +
> +static int ams_iaqcore_read_raw(struct iio_dev *indio_dev,
> +				struct iio_chan_spec const *chan, int *val,
> +				int *val2, long mask)
> +{
> +	struct ams_iaqcore_data *data = iio_priv(indio_dev);
> +	int ret = -EINVAL;
> +
> +	if (mask != IIO_CHAN_INFO_RAW)
> +		return -EINVAL;
> +
> +	mutex_lock(&data->lock);
> +	ret = ams_iaqcore_get_measurement(data);
> +	mutex_unlock(&data->lock);
> +
> +	if (ret)
> +		return ret;
> +
> +	switch (chan->address) {
> +	case AMS_IAQCORE_VOC_CO2_IDX:
> +		*val = be16_to_cpu(data->buffer.co2_ppm);
> +		return IIO_VAL_INT;
> +	case AMS_IAQCORE_VOC_RESISTANCE_IDX:
> +		*val = be32_to_cpu(data->buffer.resistance);
> +		return IIO_VAL_INT;
> +	case AMS_IAQCORE_VOC_TVOC_IDX:
> +		*val = be16_to_cpu(data->buffer.voc_ppb);
> +		return IIO_VAL_INT;
> +	}
nitpick of the day - blank line here please :)
> +	return ret;
> +}
> +
> +static const struct iio_info ams_iaqcore_info = {
> +	.read_raw	= ams_iaqcore_read_raw,
> +	.driver_module	= THIS_MODULE,
> +};
> +
> +static int ams_iaqcore_probe(struct i2c_client *client,
> +			     const struct i2c_device_id *id)
> +{
> +	struct iio_dev *indio_dev;
> +	struct ams_iaqcore_data *data;
> +
> +	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;
Would have liked a comment here on why the take one second off...
Fairly obvious though so not that important.

> +	data->last_update = jiffies - HZ;
> +	mutex_init(&data->lock);
> +
> +	indio_dev->dev.parent = &client->dev;
> +	indio_dev->info = &ams_iaqcore_info,
> +	indio_dev->name = dev_name(&client->dev);
> +	indio_dev->modes = INDIO_DIRECT_MODE;
> +
> +	indio_dev->channels = ams_iaqcore_channels;
> +	indio_dev->num_channels = ARRAY_SIZE(ams_iaqcore_channels);
> +
> +	return devm_iio_device_register(&client->dev, indio_dev);
> +}
> +
> +static const struct i2c_device_id ams_iaqcore_id[] = {
> +	{ "ams-iaq-core", 0 },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(i2c, ams_iaqcore_id);
> +
> +static const struct of_device_id ams_iaqcore_dt_ids[] = {
> +	{ .compatible = "ams,iaq-core" },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(of, ams_iaqcore_dt_ids);
> +
> +static struct i2c_driver ams_iaqcore_driver = {
> +	.driver = {
> +		.name	= "ams-iaq-core",
> +		.of_match_table = of_match_ptr(ams_iaqcore_dt_ids),
> +	},
> +	.probe = ams_iaqcore_probe,
> +	.id_table = ams_iaqcore_id,
> +};
> +module_i2c_driver(ams_iaqcore_driver);
> +
> +MODULE_AUTHOR("Matt Ranostay <mranostay@gmail.com>");
> +MODULE_DESCRIPTION("AMS iAQ-Core VOC sensors");
> +MODULE_LICENSE("GPL v2");
>