diff options
Diffstat (limited to 'drivers/iio/chemical/ccs811.c')
| -rw-r--r-- | drivers/iio/chemical/ccs811.c | 339 |
1 files changed, 339 insertions, 0 deletions
diff --git a/drivers/iio/chemical/ccs811.c b/drivers/iio/chemical/ccs811.c new file mode 100644 index 000000000000..8dbb5eddeb1f --- /dev/null +++ b/drivers/iio/chemical/ccs811.c @@ -0,0 +1,339 @@ +/* + * ccs811.c - Support for AMS CCS811 VOC Sensor + * + * Copyright (C) 2017 Narcisa Vasile <narcisaanamaria12@gmail.com> + * + * 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) { + mutex_unlock(&data->lock); + return ret; + } + + 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; + } + mutex_unlock(&data->lock); + + return ret; + + 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; + } +} + +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; + } + + 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@gmail.com>"); +MODULE_DESCRIPTION("CCS811 volatile organic compounds sensor"); +MODULE_LICENSE("GPL v2"); |