On Tue, 18 Jul 2017 14:49:11 +0300
Narcisa Ana Maria Vasile <narcisaanamaria12@xxxxxxxxx> wrote:
> On Mon, Jul 17, 2017 at 10:43:26PM +0100, Jonathan Cameron wrote:
> > On Mon, 17 Jul 2017 22:28:03 +0300
> > Narcisa Ana Maria Vasile <narcisaanamaria12@xxxxxxxxx> wrote:
> >
> > > Add support for CCS811 VOC sensor. This patch adds support
> > > for reading current and voltage across the sensor and TVOC
> > > and equivalent CO2 values.
> > >
> > > Scale and offset values have been computed according to datasheet:
> > > - For current: raw value is in microamps
> > > => 0.001 scale to convert to milliamps
> > > - For voltage: 1.65V = 1023, therefore 1650mV = 1023
> > > => 1650.0/1023 = 1.612903 scale to convert to millivolts
> > > - For eCO2: raw value range is from 400ppm to 8192ppm.
> > > => (val - 400) * (100 - 0) / (8192 - 400) + 0 =
> > > (val - 400) * 0.01283367 => offset: -400, scale = 0.012834
> > > to get a percentage value
> > > -For TVOC: raw value range is from 0ppb to 1187ppb.
> > > => (val - 0) * 100 / (1187 - 0) + 0 = val * 0.0842459 =>
> > > scale = 0.084246 for getting a percentage value
> > >
> > > Cc: Daniel Baluta <daniel.baluta@xxxxxxxxx>
> > > Cc: Alison Schofield <amsfield22@xxxxxxxxx>
> > > Signed-off-by: Narcisa Ana Maria Vasile <narcisaanamaria12@xxxxxxxxx>
> > There is one bit inline that ended up a little inelegant despite
> > being done in a theoretically acceptable way.
> >
> > So you don't have to do another round, I've tweaked it whilst applying
> > - please could you check the result is still good as I've been known
> > to mess up these little changes ;(
> >
> Where should I check for these adjustments? I checked the testing branch,
> but I didn't notice any changes applied there.
>
Gah, I got called away last night and must have pushed out the
wrong version (i.e. I failed to add the change).
Will have another go pushing it out this evening or possibly tomorrow.
Thanks for checking!
Jonathan
> Thank you,
> Narcisa
>
> > Nice little driver, looking forward to next part.
> > Jonathan
> > > ---
> > > Changes in v3:
> > > - Define macros for the hardware id value, hardware version and
> > > hardware version mask
> > > - Define mask and value macros for FW_MODE bit of status register
> > > for clarity
> > > - Define mask and value macros for APP_VALID bit of status register
> > > for clarity
> > > - Remove enum operation_mode
> > > - Add macros for operation mode masks
> > > - Write to APP_START using i2c_smbus_write_byte, instead of
> > > i2c_smbus_read_byte_data, as the datasheet requests a write of one byte
> > > to transition from boot mode to application mode
> > > - Remove check of status register after setting measurement mode
> > > as the datasheet doesn't require checking for errors after this operation
> > > - Remove set_drive_mode() function, as drive mode can be directly set
> > > with one call to i2c_smbus_write_byte_data(). The rest of the function body
> > > was just checking the STATUS register for errors, but this check was
> > > removed.
> > > - Fix race condition by holding the lock until all operations performed on
> > > the data buffer are completed; add label out_unlock, in order to
> > > make sure the lock is released in case of errors, too.
> > > - Improve comment to explicitly show the maximum waiting time for a new
> > > data sample to be ready.
> > > - Add comment to document the need for transition from boot mode to app mode
> > > - Rename ccs811_switch_to_application_mode to ccs811_start_sensor_application
> > > - Add functionality check flag for i2c_smbus_write_byte
> > > - Add comment above status register flags macros
> > > - Add comment explaining the purpose of FW_MODE bit in STATUS register
> > > - Add check for when number of tries reaches 0, while waiting for
> > > data-ready flag to be set.
> > > Note: After 1 second has passed after the first check of the data-ready
> > > flag, it goes inside the loop one more time and checks the data-ready
> > > flag again. It should then break, either because data is ready,
> > > or it is not, but number of tries has reached 0 and it will not go inside
> > > the loop again.
> > > If the "tries == 0" check is removed, it will wait 100ms more at the end,
> > > before checking the "while" condition again and exiting the loop.
> > >
> > > Changes in v2:
> > > - Add scale and offset to obtain values expressed with correct units.
> > > - RAW_READ register is not read anymore, since values for current and
> > > voltage are read using ALG_RESULT_DATA register address. Remove the
> > > check for I2C_SMBUS_WORD_DATA, since the corresponding function
> > > is not used anymore.
> > > - Define packed struct to hold data read from alg_result_data register.
> > > - Add mutex to protect readings.
> > > - Add _remove function and set chip to IDLE inside it.
> > > - Group measurement reading and "data_ready" check inside new function.
> > > - Introduce sleeps to wait for data to be ready.
> > > - Add ccs811 prefix to enum operation_mode and to STATUS macros.
> > > - Use ret instead of status variable to hold return values from functions.
> > > - Use enum operation_mode instead of int as parameter to set_drive_mode().
> > > - Drop temporary variable meas_mode.
> > > - Drop pointless comments.
> > > - Add macro for error bit in STATUS register.
> > > - Drop useless break.
> > > - Drop useless return.
> > > - Change format of multi-line comment.
> > > - Change word "SENSOR" to lowercase letters inside MODULE_DESCRIPTION.
> > > - Remove empty comment line.
> > > - Introduce MIN and MAX values to ccs811_operation_mode to detect invalid
> > > values.
> > > - Change style of braces.
> > > - Replace VOC with "volatile organic compounds" in MODULE_DESCRIPTION.
> > > - Add datasheet link.
> > > - Check hardware version in probe
> > >
> > > drivers/iio/chemical/Kconfig | 7 +
> > > drivers/iio/chemical/Makefile | 1 +
> > > drivers/iio/chemical/ccs811.c | 338 ++++++++++++++++++++++++++++++++++++++++++
> > > 3 files changed, 346 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..0e6b34a
> > > --- /dev/null
> > > +++ b/drivers/iio/chemical/ccs811.c
> > > @@ -0,0 +1,338 @@
> > > +/*
> > > + * ccs811.c - Support for AMS CCS811 VOC Sensor
> > > + *
> > > + * Copyright (C) 2017 Narcisa Vasile <narcisaanamaria12@xxxxxxxxx>
> > > + *
> > > + * Datasheet: ams.com/content/download/951091/2269479/CCS811_DS000459_3-00.pdf
> > > + *
> > > + * 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)
> > > + *
> > > + * TODO:
> > > + * 1. Make the drive mode selectable form userspace
> > > + * 2. Add support for interrupts
> > > + * 3. Adjust time to wait for data to be ready based on selected operation mode
> > > + * 4. Read error register and put the information in logs
> > > + */
> > > +
> > > +#include <linux/delay.h>
> > > +#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 CCS881_HW_ID_VALUE 0x81
> > > +#define CCS811_HW_VERSION 0x21
> > > +#define CCS811_HW_VERSION_VALUE 0x10
> > > +#define CCS811_HW_VERSION_MASK 0xF0
> > > +#define CCS811_ERR 0xE0
> > > +/* Used to transition from boot to application mode */
> > > +#define CCS811_APP_START 0xF4
> > > +
> > > +/* Status register flags */
> > > +#define CCS811_STATUS_ERROR BIT(0)
> > > +#define CCS811_STATUS_DATA_READY BIT(3)
> > > +#define CCS811_STATUS_APP_VALID_MASK BIT(4)
> > > +#define CCS811_STATUS_APP_VALID_LOADED BIT(4)
> > > +/*
> > > + * Value of FW_MODE bit of STATUS register describes the sensor's state:
> > > + * 0: Firmware is in boot mode, this allows new firmware to be loaded
> > > + * 1: Firmware is in application mode. CCS811 is ready to take ADC measurements
> > > + */
> > > +#define CCS811_STATUS_FW_MODE_MASK BIT(7)
> > > +#define CCS811_STATUS_FW_MODE_APPLICATION BIT(7)
> > > +
> > > +/* Measurement modes */
> > > +#define CCS811_MODE_IDLE 0x00
> > > +#define CCS811_MODE_IAQ_1SEC 0x10
> > > +#define CCS811_MODE_IAQ_10SEC 0x20
> > > +#define CCS811_MODE_IAQ_60SEC 0x30
> > > +#define CCS811_MODE_RAW_DATA 0x40
> > > +
> > > +#define CCS811_VOLTAGE_MASK 0x3FF
> > > +
> > > +struct ccs811_reading {
> > > + __be16 co2;
> > > + __be16 voc;
> > > + u8 status;
> > > + u8 error;
> > > + __be16 resistance;
> > > +} __attribute__((__packed__));
> > > +
> > > +struct ccs811_data {
> > > + struct i2c_client *client;
> > > + struct mutex lock; /* Protect readings */
> > > + struct ccs811_reading buffer;
> > > +};
> > > +
> > > +static const struct iio_chan_spec ccs811_channels[] = {
> > > + {
> > > + .type = IIO_CURRENT,
> > > + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
> > > + BIT(IIO_CHAN_INFO_SCALE)
> > > + }, {
> > > + .type = IIO_VOLTAGE,
> > > + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
> > > + BIT(IIO_CHAN_INFO_SCALE)
> > > + }, {
> > > + .type = IIO_CONCENTRATION,
> > > + .channel2 = IIO_MOD_CO2,
> > > + .modified = 1,
> > > + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
> > > + BIT(IIO_CHAN_INFO_OFFSET) |
> > > + BIT(IIO_CHAN_INFO_SCALE)
> > > + }, {
> > > + .type = IIO_CONCENTRATION,
> > > + .channel2 = IIO_MOD_VOC,
> > > + .modified = 1,
> > > + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
> > > + BIT(IIO_CHAN_INFO_SCALE)
> > > + },
> > > +};
> > > +
> > > +/*
> > > + * The CCS811 powers-up in boot mode. A setup write to CCS811_APP_START will
> > > + * transition the sensor to application mode.
> > > + */
> > > +static int ccs811_start_sensor_application(struct i2c_client *client)
> > > +{
> > > + int ret;
> > > +
> > > + ret = i2c_smbus_read_byte_data(client, CCS811_STATUS);
> > > + if (ret < 0)
> > > + return ret;
> > > +
> > > + if ((ret & CCS811_STATUS_APP_VALID_MASK) !=
> > > + CCS811_STATUS_APP_VALID_LOADED)
> > > + return -EIO;
> > > +
> > > + ret = i2c_smbus_write_byte(client, CCS811_APP_START);
> > > + if (ret < 0)
> > > + return ret;
> > > +
> > > + ret = i2c_smbus_read_byte_data(client, CCS811_STATUS);
> > > + if (ret < 0)
> > > + return ret;
> > > +
> > > + if ((ret & CCS811_STATUS_FW_MODE_MASK) !=
> > > + CCS811_STATUS_FW_MODE_APPLICATION) {
> > > + dev_err(&client->dev, "Application failed to start. Sensor is still in boot mode.\n");
> > > + return -EIO;
> > > + }
> > > +
> > > + return 0;
> > > +}
> > > +
> > > +static int ccs811_setup(struct i2c_client *client)
> > > +{
> > > + int ret;
> > > +
> > > + ret = ccs811_start_sensor_application(client);
> > > + if (ret < 0)
> > > + return ret;
> > > +
> > > + return i2c_smbus_write_byte_data(client, CCS811_MEAS_MODE,
> > > + CCS811_MODE_IAQ_1SEC);
> > > +}
> > > +
> > > +static int ccs811_get_measurement(struct ccs811_data *data)
> > > +{
> > > + int ret, tries = 11;
> > > +
> > > + /* Maximum waiting time: 1s, as measurements are made every second */
> > > + while (tries-- > 0) {
> > > + ret = i2c_smbus_read_byte_data(data->client, CCS811_STATUS);
> > > + if (ret < 0)
> > > + return ret;
> > > +
> > > + if ((ret & CCS811_STATUS_DATA_READY) || tries == 0)
> > > + break;
> > > + msleep(100);
> > > + }
> > > + if (!(ret & CCS811_STATUS_DATA_READY))
> > > + return -EIO;
> > > +
> > > + return i2c_smbus_read_i2c_block_data(data->client,
> > > + CCS811_ALG_RESULT_DATA, 8,
> > > + (char *)&data->buffer);
> > > +}
> > > +
> > > +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;
> > > +
> > > + switch (mask) {
> > > + case IIO_CHAN_INFO_RAW:
> > > + mutex_lock(&data->lock);
> > > + ret = ccs811_get_measurement(data);
> > > + if (ret < 0)
> > I know we always argue in favour of a single cleanup point
> > but this has ended up rather inelegant. I'd put the addition
> > unlock here that will allow to bring it into the outer case
> > statement and end up with a cleaner bit of code.
> >
> > If this is all that is left, I'll do it in the interests
> > of speed and moving on to more interesting new stuff.
> >
> > Only obvious alternative would have been to break this block
> > out to a separate function with error handling, but that seems
> > like overkill on this occasion.
> >
> > Anyhow, please check the result.
> > > + goto out_unlock;
> > > +
> > > + switch (chan->type) {
> > > + case IIO_VOLTAGE:
> > > + *val = be16_to_cpu(data->buffer.resistance) &
> > > + CCS811_VOLTAGE_MASK;
> > > + ret = IIO_VAL_INT;
> > > + break;
> > > + case IIO_CURRENT:
> > > + *val = be16_to_cpu(data->buffer.resistance) >> 10;
> > > + ret = IIO_VAL_INT;
> > > + break;
> > > + case IIO_CONCENTRATION:
> > > + switch (chan->channel2) {
> > > + case IIO_MOD_CO2:
> > > + *val = be16_to_cpu(data->buffer.co2);
> > > + ret = IIO_VAL_INT;
> > > + break;
> > > + case IIO_MOD_VOC:
> > > + *val = be16_to_cpu(data->buffer.voc);
> > > + ret = IIO_VAL_INT;
> > > + break;
> > > + default:
> > > + ret = -EINVAL;
> > > + }
> > > + break;
> > > + default:
> > > + ret = -EINVAL;
> > > + }
> > > + break;
> > > + case IIO_CHAN_INFO_SCALE:
> > > + switch (chan->type) {
> > > + case IIO_VOLTAGE:
> > > + *val = 1;
> > > + *val2 = 612903;
> > > + return IIO_VAL_INT_PLUS_MICRO;
> > > + case IIO_CURRENT:
> > > + *val = 0;
> > > + *val2 = 1000;
> > > + return IIO_VAL_INT_PLUS_MICRO;
> > > + case IIO_CONCENTRATION:
> > > + switch (chan->channel2) {
> > > + case IIO_MOD_CO2:
> > > + *val = 0;
> > > + *val2 = 12834;
> > > + return IIO_VAL_INT_PLUS_MICRO;
> > > + case IIO_MOD_VOC:
> > > + *val = 0;
> > > + *val2 = 84246;
> > > + return IIO_VAL_INT_PLUS_MICRO;
> > > + default:
> > > + return -EINVAL;
> > > + }
> > > + default:
> > > + return -EINVAL;
> > > + }
> > > + case IIO_CHAN_INFO_OFFSET:
> > > + if (!(chan->type == IIO_CONCENTRATION &&
> > > + chan->channel2 == IIO_MOD_CO2))
> > > + return -EINVAL;
> > > + *val = -400;
> > > + return IIO_VAL_INT;
> > > + default:
> > > + return -EINVAL;
> > > + }
> > > +
> > > +out_unlock:
> > > + mutex_unlock(&data->lock);
> > > + return ret;
> > > +}
> > > +
> > > +static const struct iio_info ccs811_info = {
> > > + .read_raw = ccs811_read_raw,
> > > + .driver_module = THIS_MODULE,
> > > +};
> > > +
> > > +static int ccs811_probe(struct i2c_client *client,
> > > + const struct i2c_device_id *id)
> > > +{
> > > + struct iio_dev *indio_dev;
> > > + struct ccs811_data *data;
> > > + int ret;
> > > +
> > > + if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_WRITE_BYTE
> > > + | I2C_FUNC_SMBUS_BYTE_DATA
> > > + | I2C_FUNC_SMBUS_READ_I2C_BLOCK))
> > > + return -EOPNOTSUPP;
> > > +
> > > + /* Check hardware id (should be 0x81 for this family of devices) */
> > > + ret = i2c_smbus_read_byte_data(client, CCS811_HW_ID);
> > > + if (ret < 0)
> > > + return ret;
> > > +
> > > + if (ret != CCS881_HW_ID_VALUE) {
> > > + dev_err(&client->dev, "hardware id doesn't match CCS81x\n");
> > > + return -ENODEV;
> > > + }
> > > +
> > > + ret = i2c_smbus_read_byte_data(client, CCS811_HW_VERSION);
> > > + if (ret < 0)
> > > + return ret;
> > > +
> > > + if ((ret & CCS811_HW_VERSION_MASK) != CCS811_HW_VERSION_VALUE) {
> > > + dev_err(&client->dev, "no CCS811 sensor\n");
> > > + return -ENODEV;
> > This test may prove a little over zealous in the future if the
> > interface tends to stay the same whilst tweaks are made elsewhere.
> > Still we don't know yet, so let us leave this here for now.
> > > + }
> > > +
> > > + 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;
> > > +
> > > + mutex_init(&data->lock);
> > > +
> > > + 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 iio_device_register(indio_dev);
> > > +}
> > > +
> > > +static int ccs811_remove(struct i2c_client *client)
> > > +{
> > > + struct iio_dev *indio_dev = i2c_get_clientdata(client);
> > > +
> > > + iio_device_unregister(indio_dev);
> > > +
> > > + return i2c_smbus_write_byte_data(client, CCS811_MEAS_MODE,
> > > + CCS811_MODE_IDLE);
> > > +}
> > > +
> > > +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,
> > > + .remove = ccs811_remove,
> > > + .id_table = ccs811_id,
> > > +};
> > > +module_i2c_driver(ccs811_driver);
> > > +
> > > +MODULE_AUTHOR("Narcisa Vasile <narcisaanamaria12@xxxxxxxxx>");
> > > +MODULE_DESCRIPTION("CCS811 volatile organic compounds sensor");
> > > +MODULE_LICENSE("GPL v2");
> >
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