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.
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,
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
+
+#define CCS811_VOLTAGE_MASK 0x3FF
+
+#define STATUS_DATA_READY BIT(3)
+#define STATUS_APP_VALID BIT(4)
+#define STATUS_FW_MODE BIT(7)
+
+enum operation_mode {
+ 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;
+
+ status = i2c_smbus_read_byte_data(client, CCS811_STATUS);
+ if (status < 0)
+ return status;
+
+ if (!(status & STATUS_DATA_READY))
+ return -EAGAIN;
+
+ return 0;
+}
+
+static int ccs811_set_drive_mode(struct i2c_client *client, int mode)
+{
+ int ret, status, meas_mode = 0;
+
+ if (mode < 0 || mode > 4)
+ return -EINVAL;
+
+ meas_mode = mode << 4;
+
+ 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 */
+ if (status & 1)
+ return -EIO;
+
+ return 0;
+}
+
+static int ccs811_switch_to_application_mode(struct i2c_client *client)
+{
+ int status, ret;
+
+ 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);
+ 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;
+
+ 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;
+ return IIO_VAL_INT;
+ case IIO_CURRENT:
+ *val = ret >> 10;
+ return IIO_VAL_INT;
+ default:
+ return -EINVAL;
+ }
+ break;
+ 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
+ * requested or status error bit was set
+ */
+ if (ret != 5 || (data->buffer[4] & 1))
+ return -EIO;
+
+ switch (chan->channel2) {
+ case IIO_MOD_CO2:
+ *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;
+}
+
+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);
+}
+
+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");
+MODULE_LICENSE("GPL v2");
--
1.9.1
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