1 // SPDX-License-Identifier: GPL-2.0-only
3 * ccs811.c - Support for AMS CCS811 VOC Sensor
5 * Copyright (C) 2017 Narcisa Vasile <narcisaanamaria12@gmail.com>
7 * Datasheet: ams.com/content/download/951091/2269479/CCS811_DS000459_3-00.pdf
9 * IIO driver for AMS CCS811 (I2C address 0x5A/0x5B set by ADDR Low/High)
12 * 1. Make the drive mode selectable form userspace
13 * 2. Add support for interrupts
14 * 3. Adjust time to wait for data to be ready based on selected operation mode
15 * 4. Read error register and put the information in logs
18 #include <linux/delay.h>
19 #include <linux/i2c.h>
20 #include <linux/iio/iio.h>
21 #include <linux/iio/buffer.h>
22 #include <linux/iio/trigger.h>
23 #include <linux/iio/triggered_buffer.h>
24 #include <linux/iio/trigger_consumer.h>
25 #include <linux/module.h>
27 #define CCS811_STATUS 0x00
28 #define CCS811_MEAS_MODE 0x01
29 #define CCS811_ALG_RESULT_DATA 0x02
30 #define CCS811_RAW_DATA 0x03
31 #define CCS811_HW_ID 0x20
32 #define CCS811_HW_ID_VALUE 0x81
33 #define CCS811_HW_VERSION 0x21
34 #define CCS811_HW_VERSION_VALUE 0x10
35 #define CCS811_HW_VERSION_MASK 0xF0
36 #define CCS811_ERR 0xE0
37 /* Used to transition from boot to application mode */
38 #define CCS811_APP_START 0xF4
40 /* Status register flags */
41 #define CCS811_STATUS_ERROR BIT(0)
42 #define CCS811_STATUS_DATA_READY BIT(3)
43 #define CCS811_STATUS_APP_VALID_MASK BIT(4)
44 #define CCS811_STATUS_APP_VALID_LOADED BIT(4)
46 * Value of FW_MODE bit of STATUS register describes the sensor's state:
47 * 0: Firmware is in boot mode, this allows new firmware to be loaded
48 * 1: Firmware is in application mode. CCS811 is ready to take ADC measurements
50 #define CCS811_STATUS_FW_MODE_MASK BIT(7)
51 #define CCS811_STATUS_FW_MODE_APPLICATION BIT(7)
53 /* Measurement modes */
54 #define CCS811_MODE_IDLE 0x00
55 #define CCS811_MODE_IAQ_1SEC 0x10
56 #define CCS811_MODE_IAQ_10SEC 0x20
57 #define CCS811_MODE_IAQ_60SEC 0x30
58 #define CCS811_MODE_RAW_DATA 0x40
60 #define CCS811_MEAS_MODE_INTERRUPT BIT(3)
62 #define CCS811_VOLTAGE_MASK 0x3FF
64 struct ccs811_reading {
70 } __attribute__((__packed__));
73 struct i2c_client *client;
74 struct mutex lock; /* Protect readings */
75 struct ccs811_reading buffer;
76 struct iio_trigger *drdy_trig;
80 static const struct iio_chan_spec ccs811_channels[] = {
83 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
84 BIT(IIO_CHAN_INFO_SCALE),
88 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
89 BIT(IIO_CHAN_INFO_SCALE),
92 .type = IIO_CONCENTRATION,
93 .channel2 = IIO_MOD_CO2,
95 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
96 BIT(IIO_CHAN_INFO_SCALE),
102 .endianness = IIO_BE,
105 .type = IIO_CONCENTRATION,
106 .channel2 = IIO_MOD_VOC,
108 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
109 BIT(IIO_CHAN_INFO_SCALE),
115 .endianness = IIO_BE,
118 IIO_CHAN_SOFT_TIMESTAMP(2),
122 * The CCS811 powers-up in boot mode. A setup write to CCS811_APP_START will
123 * transition the sensor to application mode.
125 static int ccs811_start_sensor_application(struct i2c_client *client)
129 ret = i2c_smbus_read_byte_data(client, CCS811_STATUS);
133 if ((ret & CCS811_STATUS_FW_MODE_APPLICATION))
136 if ((ret & CCS811_STATUS_APP_VALID_MASK) !=
137 CCS811_STATUS_APP_VALID_LOADED)
140 ret = i2c_smbus_write_byte(client, CCS811_APP_START);
144 ret = i2c_smbus_read_byte_data(client, CCS811_STATUS);
148 if ((ret & CCS811_STATUS_FW_MODE_MASK) !=
149 CCS811_STATUS_FW_MODE_APPLICATION) {
150 dev_err(&client->dev, "Application failed to start. Sensor is still in boot mode.\n");
157 static int ccs811_setup(struct i2c_client *client)
161 ret = ccs811_start_sensor_application(client);
165 return i2c_smbus_write_byte_data(client, CCS811_MEAS_MODE,
166 CCS811_MODE_IAQ_1SEC);
169 static int ccs811_get_measurement(struct ccs811_data *data)
173 /* Maximum waiting time: 1s, as measurements are made every second */
174 while (tries-- > 0) {
175 ret = i2c_smbus_read_byte_data(data->client, CCS811_STATUS);
179 if ((ret & CCS811_STATUS_DATA_READY) || tries == 0)
183 if (!(ret & CCS811_STATUS_DATA_READY))
186 return i2c_smbus_read_i2c_block_data(data->client,
187 CCS811_ALG_RESULT_DATA, 8,
188 (char *)&data->buffer);
191 static int ccs811_read_raw(struct iio_dev *indio_dev,
192 struct iio_chan_spec const *chan,
193 int *val, int *val2, long mask)
195 struct ccs811_data *data = iio_priv(indio_dev);
199 case IIO_CHAN_INFO_RAW:
200 ret = iio_device_claim_direct_mode(indio_dev);
203 mutex_lock(&data->lock);
204 ret = ccs811_get_measurement(data);
206 mutex_unlock(&data->lock);
207 iio_device_release_direct_mode(indio_dev);
211 switch (chan->type) {
213 *val = be16_to_cpu(data->buffer.raw_data) &
218 *val = be16_to_cpu(data->buffer.raw_data) >> 10;
221 case IIO_CONCENTRATION:
222 switch (chan->channel2) {
224 *val = be16_to_cpu(data->buffer.co2);
228 *val = be16_to_cpu(data->buffer.voc);
238 mutex_unlock(&data->lock);
239 iio_device_release_direct_mode(indio_dev);
243 case IIO_CHAN_INFO_SCALE:
244 switch (chan->type) {
248 return IIO_VAL_INT_PLUS_MICRO;
252 return IIO_VAL_INT_PLUS_MICRO;
253 case IIO_CONCENTRATION:
254 switch (chan->channel2) {
258 return IIO_VAL_INT_PLUS_MICRO;
262 return IIO_VAL_INT_PLUS_NANO;
274 static const struct iio_info ccs811_info = {
275 .read_raw = ccs811_read_raw,
278 static int ccs811_set_trigger_state(struct iio_trigger *trig,
281 struct iio_dev *indio_dev = iio_trigger_get_drvdata(trig);
282 struct ccs811_data *data = iio_priv(indio_dev);
285 ret = i2c_smbus_read_byte_data(data->client, CCS811_MEAS_MODE);
290 ret |= CCS811_MEAS_MODE_INTERRUPT;
292 ret &= ~CCS811_MEAS_MODE_INTERRUPT;
294 data->drdy_trig_on = state;
296 return i2c_smbus_write_byte_data(data->client, CCS811_MEAS_MODE, ret);
299 static const struct iio_trigger_ops ccs811_trigger_ops = {
300 .set_trigger_state = ccs811_set_trigger_state,
303 static irqreturn_t ccs811_trigger_handler(int irq, void *p)
305 struct iio_poll_func *pf = p;
306 struct iio_dev *indio_dev = pf->indio_dev;
307 struct ccs811_data *data = iio_priv(indio_dev);
308 struct i2c_client *client = data->client;
309 s16 buf[8]; /* s16 eCO2 + s16 TVOC + padding + 8 byte timestamp */
312 ret = i2c_smbus_read_i2c_block_data(client, CCS811_ALG_RESULT_DATA, 4,
315 dev_err(&client->dev, "cannot read sensor data\n");
319 iio_push_to_buffers_with_timestamp(indio_dev, buf,
320 iio_get_time_ns(indio_dev));
323 iio_trigger_notify_done(indio_dev->trig);
328 static irqreturn_t ccs811_data_rdy_trigger_poll(int irq, void *private)
330 struct iio_dev *indio_dev = private;
331 struct ccs811_data *data = iio_priv(indio_dev);
333 if (data->drdy_trig_on)
334 iio_trigger_poll(data->drdy_trig);
339 static int ccs811_probe(struct i2c_client *client,
340 const struct i2c_device_id *id)
342 struct iio_dev *indio_dev;
343 struct ccs811_data *data;
346 if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_WRITE_BYTE
347 | I2C_FUNC_SMBUS_BYTE_DATA
348 | I2C_FUNC_SMBUS_READ_I2C_BLOCK))
351 /* Check hardware id (should be 0x81 for this family of devices) */
352 ret = i2c_smbus_read_byte_data(client, CCS811_HW_ID);
356 if (ret != CCS811_HW_ID_VALUE) {
357 dev_err(&client->dev, "hardware id doesn't match CCS81x\n");
361 ret = i2c_smbus_read_byte_data(client, CCS811_HW_VERSION);
365 if ((ret & CCS811_HW_VERSION_MASK) != CCS811_HW_VERSION_VALUE) {
366 dev_err(&client->dev, "no CCS811 sensor\n");
370 indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
374 ret = ccs811_setup(client);
378 data = iio_priv(indio_dev);
379 i2c_set_clientdata(client, indio_dev);
380 data->client = client;
382 mutex_init(&data->lock);
384 indio_dev->dev.parent = &client->dev;
385 indio_dev->name = id->name;
386 indio_dev->info = &ccs811_info;
387 indio_dev->modes = INDIO_DIRECT_MODE;
389 indio_dev->channels = ccs811_channels;
390 indio_dev->num_channels = ARRAY_SIZE(ccs811_channels);
392 if (client->irq > 0) {
393 ret = devm_request_threaded_irq(&client->dev, client->irq,
394 ccs811_data_rdy_trigger_poll,
396 IRQF_TRIGGER_FALLING |
398 "ccs811_irq", indio_dev);
400 dev_err(&client->dev, "irq request error %d\n", -ret);
404 data->drdy_trig = devm_iio_trigger_alloc(&client->dev,
408 if (!data->drdy_trig) {
413 data->drdy_trig->dev.parent = &client->dev;
414 data->drdy_trig->ops = &ccs811_trigger_ops;
415 iio_trigger_set_drvdata(data->drdy_trig, indio_dev);
416 indio_dev->trig = data->drdy_trig;
417 iio_trigger_get(indio_dev->trig);
418 ret = iio_trigger_register(data->drdy_trig);
423 ret = iio_triggered_buffer_setup(indio_dev, NULL,
424 ccs811_trigger_handler, NULL);
427 dev_err(&client->dev, "triggered buffer setup failed\n");
428 goto err_trigger_unregister;
431 ret = iio_device_register(indio_dev);
433 dev_err(&client->dev, "unable to register iio device\n");
434 goto err_buffer_cleanup;
439 iio_triggered_buffer_cleanup(indio_dev);
440 err_trigger_unregister:
442 iio_trigger_unregister(data->drdy_trig);
444 i2c_smbus_write_byte_data(client, CCS811_MEAS_MODE, CCS811_MODE_IDLE);
449 static int ccs811_remove(struct i2c_client *client)
451 struct iio_dev *indio_dev = i2c_get_clientdata(client);
452 struct ccs811_data *data = iio_priv(indio_dev);
454 iio_device_unregister(indio_dev);
455 iio_triggered_buffer_cleanup(indio_dev);
457 iio_trigger_unregister(data->drdy_trig);
459 return i2c_smbus_write_byte_data(client, CCS811_MEAS_MODE,
463 static const struct i2c_device_id ccs811_id[] = {
467 MODULE_DEVICE_TABLE(i2c, ccs811_id);
469 static struct i2c_driver ccs811_driver = {
473 .probe = ccs811_probe,
474 .remove = ccs811_remove,
475 .id_table = ccs811_id,
477 module_i2c_driver(ccs811_driver);
479 MODULE_AUTHOR("Narcisa Vasile <narcisaanamaria12@gmail.com>");
480 MODULE_DESCRIPTION("CCS811 volatile organic compounds sensor");
481 MODULE_LICENSE("GPL v2");