> Add support for CCS811 VOC sensor. This patch adds support
> for reading current and voltage across the sensor and TVOC
> and equivalent CO2 processed values.
nice, comments below
link to datasheet would be nice
should list limitations and TODOs, e.g. interrupt support, NTC
> Signed-off-by: Narcisa Ana Maria Vasile <narcisaanamaria12@xxxxxxxxx>
> ---
> This patch introduces a probe function and adds support for readings
> from CCS811 sensor. In probe function, ccs811_setup() function is called
> to perform initial setup of the sensor:
> * ccs811_switch_to_application_mode() assures transition from boot mode
> to application mode, by first checking for a valid application and then
> selecting the APP_START register in order to start running the loaded app.
>
> * ccs811_set_drive_mode configures the sensor in the desired operating mode.
>
> ccs811_read_raw performs readings from the 4 defined channels:
> - current and voltage are read from the 2-byte RAW_DATA register.
> 6 bits represent the current and the lower 10 bits represent
> the voltage across the sensor.
>
> - eCO2 and TVOC are read from the 8-byte ALG_RESULT_DATA register.
> Only 5 bytes are read here: first 2 bytes represent equivalent CO2,
> which ranges from 400 ppm to 8192 ppm; next 2 bytes represent TVOC,
> varying from 0 ppb to 1187 ppb. Last byte is the status register,
see sysfs-bus-iio; IIO_CONCENTRATION should be a percentage value
> which is read in order to check for errors.
>
> drivers/iio/chemical/Kconfig | 7 ++
> drivers/iio/chemical/Makefile | 1 +
> drivers/iio/chemical/ccs811.c | 274 ++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 282 insertions(+)
> create mode 100644 drivers/iio/chemical/ccs811.c
>
> diff --git a/drivers/iio/chemical/Kconfig b/drivers/iio/chemical/Kconfig
> index cea7f98..4d799b5 100644
> --- a/drivers/iio/chemical/Kconfig
> +++ b/drivers/iio/chemical/Kconfig
> @@ -21,6 +21,13 @@ config ATLAS_PH_SENSOR
> To compile this driver as module, choose M here: the
> module will be called atlas-ph-sensor.
>
> +config CCS811
> + tristate "AMS CCS811 VOC sensor"
> + depends on I2C
> + help
> + Say Y here to build I2C interface support for the AMS
> + CCS811 VOC (Volatile Organic Compounds) sensor
> +
> config IAQCORE
> tristate "AMS iAQ-Core VOC sensors"
> depends on I2C
> diff --git a/drivers/iio/chemical/Makefile b/drivers/iio/chemical/Makefile
> index b02202b..a629b29 100644
> --- a/drivers/iio/chemical/Makefile
> +++ b/drivers/iio/chemical/Makefile
> @@ -4,5 +4,6 @@
>
> # When adding new entries keep the list in alphabetical order
> obj-$(CONFIG_ATLAS_PH_SENSOR) += atlas-ph-sensor.o
> +obj-$(CONFIG_CCS811) += ccs811.o
> obj-$(CONFIG_IAQCORE) += ams-iaq-core.o
> obj-$(CONFIG_VZ89X) += vz89x.o
> diff --git a/drivers/iio/chemical/ccs811.c b/drivers/iio/chemical/ccs811.c
> new file mode 100644
> index 0000000..2d736d4
> --- /dev/null
> +++ b/drivers/iio/chemical/ccs811.c
> @@ -0,0 +1,274 @@
> +/*
> + * ccs811.c - Support for AMS CCS811 VOC Sensor
> + *
> + * Copyright (C) 2017 Narcisa Vasile <narcisaanamaria12@xxxxxxxxx>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + *
> + * IIO driver for AMS CCS811 (I2C address 0x5A/0x5B set by ADDR Low/High)
> + *
> + */
> +
> +#include <linux/i2c.h>
> +#include <linux/iio/iio.h>
> +#include <linux/module.h>
> +
> +#define CCS811_STATUS 0x00
> +#define CCS811_MEAS_MODE 0x01
> +#define CCS811_ALG_RESULT_DATA 0x02
> +#define CCS811_RAW_DATA 0x03
> +#define CCS811_HW_ID 0x20
> +#define CCS811_ERR 0xE0
> +#define CCS811_APP_START 0xF4
APP_START is undocumented?
> +
> +#define CCS811_VOLTAGE_MASK 0x3FF
> +
> +#define STATUS_DATA_READY BIT(3)
> +#define STATUS_APP_VALID BIT(4)
> +#define STATUS_FW_MODE BIT(7)
prefix please
> +
> +enum operation_mode {
prefix please
> + CCS811_MODE_IDLE = 0,
> + CCS811_MODE_IAQ_SEC_1 = 1,
> + CCS811_MODE_IAQ_SEC_10 = 2,
> + CCS811_MODE_IAQ_SEC_60 = 3,
> + CCS811_MODE_RAW_DATA = 4
> +};
> +
> +struct ccs811_data {
> + struct i2c_client *client;
> + u8 buffer[8];
> +};
> +
> +static const struct iio_chan_spec ccs811_channels[] = {
> + {
> + .type = IIO_CURRENT,
> + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW)
> + },
> + {
> + .type = IIO_VOLTAGE,
> + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW)
> + },
> + {
> + .type = IIO_CONCENTRATION,
> + .channel2 = IIO_MOD_CO2,
> + .modified = 1,
> + .info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
> + },
> + {
> + .type = IIO_CONCENTRATION,
> + .channel2 = IIO_MOD_VOC,
> + .modified = 1,
> + .info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
> + },
> +};
> +
> +static int ccs811_data_ready(struct i2c_client *client)
> +{
> + int status;
maybe use 'ret' as everywhere else
> +
> + status = i2c_smbus_read_byte_data(client, CCS811_STATUS);
> + if (status < 0)
> + return status;
> +
> + if (!(status & STATUS_DATA_READY))
> + return -EAGAIN;
most other drivers wait for data to become ready instead of erroring out
> +
> + return 0;
> +}
> +
> +static int ccs811_set_drive_mode(struct i2c_client *client, int mode)
use
enum operation_mode
instead of int?
> +{
> + int ret, status, meas_mode = 0;
no need to initialize meas_mode
> +
> + if (mode < 0 || mode > 4)
> + return -EINVAL;
> +
> + meas_mode = mode << 4;
temporary variable needed?
> +
> + ret = i2c_smbus_write_byte_data(client, CCS811_MEAS_MODE, meas_mode);
> + if (ret < 0)
> + return ret;
> +
> + /* Check status for errors */
> + status = i2c_smbus_read_byte_data(client, CCS811_STATUS);
> + if (status < 0)
> + return status;
> +
> + /* First bit of status is set to 1, if an error occurred */
comments here are rather pointless
> + if (status & 1)
maybe a #define? there are already _STATUS BIT()s
> + return -EIO;
> +
> + return 0;
> +}
> +
> +static int ccs811_switch_to_application_mode(struct i2c_client *client)
> +{
> + int status, ret;
both needed?
> +
> + status = i2c_smbus_read_byte_data(client, CCS811_STATUS);
> + if (status < 0)
> + return status;
> +
> + if (!(status & STATUS_APP_VALID))
> + return -EIO;
> +
> + ret = i2c_smbus_read_byte_data(client, CCS811_APP_START);
> + if (ret < 0)
> + return ret;
> +
> + status = i2c_smbus_read_byte_data(client, CCS811_STATUS);
> + if (status < 0)
> + return status;
> +
> + if (!(status & STATUS_FW_MODE))
> + return -EIO;
> +
> + return 0;
> +}
> +
> +static int ccs811_setup(struct i2c_client *client)
> +{
> + int ret;
> +
> + ret = ccs811_switch_to_application_mode(client);
> + if (ret < 0)
> + return ret;
> +
> + ret = ccs811_set_drive_mode(client, CCS811_MODE_IAQ_SEC_1);
to would be nice to expose the 1 second interval to userspace... (or at
least note this as a TODO)
> + if (ret < 0)
> + return ret;
> +
> + return 0;
> +}
> +
> +static int ccs811_read_raw(struct iio_dev *indio_dev,
> + struct iio_chan_spec const *chan,
> + int *val, int *val2, long mask)
> +{
> + struct ccs811_data *data = iio_priv(indio_dev);
> + int ret;
> +
> + ret = ccs811_data_ready(data->client);
> + if (ret < 0)
> + return ret;
I think there should be a mutex so that
data_ready() and read()
are executed in a critical section
> +
> + switch (mask) {
> + case IIO_CHAN_INFO_RAW:
> + ret = i2c_smbus_read_word_swapped(data->client,
> + CCS811_RAW_DATA);
> + if (ret < 0)
> + return ret;
> +
> + switch (chan->type) {
> + case IIO_VOLTAGE:
> + *val = ret & CCS811_VOLTAGE_MASK;
this should be in millivolts (after _SCALE, _OFFSET)?
datasheet says that 1023 = 1.65V
> + return IIO_VAL_INT;
> + case IIO_CURRENT:
this should be in milliamps?
datasheet says this is 0 to 63 microamps...
> + *val = ret >> 10;
> + return IIO_VAL_INT;
> + default:
> + return -EINVAL;
> + }
> + break;
break not needed
> + case IIO_CHAN_INFO_PROCESSED:
> + if (chan->type != IIO_CONCENTRATION)
> + return -EINVAL;
> +
> + ret = i2c_smbus_read_i2c_block_data(data->client,
> + CCS811_ALG_RESULT_DATA,
> + 5, data->buffer);
> + if (ret < 0)
> + return ret;
> +
> + /* If the number of bytes read is different than what was
proper multi-line comment format please
/*
*
*/
> + * requested or status error bit was set
> + */
> + if (ret != 5 || (data->buffer[4] & 1))
> + return -EIO;
> +
> + switch (chan->channel2) {
> + case IIO_MOD_CO2:
data->buffer could be a (packed) struct?
__be16 co2;
__be16 voc;
u8 status;
?
> + *val = data->buffer[0] * 256 + data->buffer[1];
> + return IIO_VAL_INT;
> + case IIO_MOD_VOC:
> + *val = data->buffer[2] * 256 + data->buffer[3];
> + return IIO_VAL_INT;
> + default:
> + return -EINVAL;
> + }
> + break;
> + default:
> + return -EINVAL;
> + }
> + return -EINVAL;
return not needed
> +}
> +
> +static const struct iio_info ccs811_info = {
> + .read_raw = ccs811_read_raw,
> +};
> +
> +static int ccs811_probe(struct i2c_client *client,
> + const struct i2c_device_id *id)
> +{
> + struct iio_dev *indio_dev;
> + struct ccs811_data *data;
> + int hwid, ret;
> +
> + if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_BYTE_DATA
> + | I2C_FUNC_SMBUS_WORD_DATA
> + | I2C_FUNC_SMBUS_READ_I2C_BLOCK))
> + return -EOPNOTSUPP;
> +
> + /* Check hardware id (should be 0x81 for this family of devices) */
> + hwid = i2c_smbus_read_byte_data(client, CCS811_HW_ID);
> + if (hwid < 0)
> + return hwid;
> +
> + if (hwid != 0x81) {
> + dev_err(&client->dev, "no CCS811 sensor\n");
> + return -ENODEV;
> + }
> +
> + indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
> + if (!indio_dev)
> + return -ENOMEM;
> +
> + ret = ccs811_setup(client);
> + if (ret < 0)
> + return ret;
> +
> + data = iio_priv(indio_dev);
> + i2c_set_clientdata(client, indio_dev);
> + data->client = client;
> +
> + indio_dev->dev.parent = &client->dev;
> + indio_dev->name = id->name;
> + indio_dev->info = &ccs811_info;
> +
> + indio_dev->channels = ccs811_channels;
> + indio_dev->num_channels = ARRAY_SIZE(ccs811_channels);
> +
> + return devm_iio_device_register(&client->dev, indio_dev);
set chip to idle if _register fails?
maye set chip to idle in _remove()?
> +}
> +
> +static const struct i2c_device_id ccs811_id[] = {
> + {"ccs811", 0},
> + { }
> +};
> +MODULE_DEVICE_TABLE(i2c, ccs811_id);
> +
> +static struct i2c_driver ccs811_driver = {
> + .driver = {
> + .name = "ccs811",
> + },
> + .probe = ccs811_probe,
> + .id_table = ccs811_id,
> +};
> +module_i2c_driver(ccs811_driver);
> +
> +MODULE_AUTHOR("Narcisa Vasile <narcisaanamaria12@xxxxxxxxx>");
> +MODULE_DESCRIPTION("CCS811 VOC SENSOR");
sensor
> +MODULE_LICENSE("GPL v2");
> --
> 1.9.1
>
> --
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--
Peter Meerwald-Stadler
Mobile: +43 664 24 44 418
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