1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * ccs811.c - Support for AMS CCS811 VOC Sensor
4 *
5 * Copyright (C) 2017 Narcisa Vasile <narcisaanamaria12@gmail.com>
6 *
7 * Datasheet: ams.com/content/download/951091/2269479/CCS811_DS000459_3-00.pdf
8 *
9 * IIO driver for AMS CCS811 (I2C address 0x5A/0x5B set by ADDR Low/High)
10 *
11 * TODO:
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
16 */
17
18 #include <linux/delay.h>
19 #include <linux/gpio/consumer.h>
20 #include <linux/i2c.h>
21 #include <linux/iio/iio.h>
22 #include <linux/iio/buffer.h>
23 #include <linux/iio/trigger.h>
24 #include <linux/iio/triggered_buffer.h>
25 #include <linux/iio/trigger_consumer.h>
26 #include <linux/module.h>
27
28 #define CCS811_STATUS 0x00
29 #define CCS811_MEAS_MODE 0x01
30 #define CCS811_ALG_RESULT_DATA 0x02
31 #define CCS811_RAW_DATA 0x03
32 #define CCS811_HW_ID 0x20
33 #define CCS811_HW_ID_VALUE 0x81
34 #define CCS811_HW_VERSION 0x21
35 #define CCS811_HW_VERSION_VALUE 0x10
36 #define CCS811_HW_VERSION_MASK 0xF0
37 #define CCS811_ERR 0xE0
38 /* Used to transition from boot to application mode */
39 #define CCS811_APP_START 0xF4
40 #define CCS811_SW_RESET 0xFF
41
42 /* Status register flags */
43 #define CCS811_STATUS_ERROR BIT(0)
44 #define CCS811_STATUS_DATA_READY BIT(3)
45 #define CCS811_STATUS_APP_VALID_MASK BIT(4)
46 #define CCS811_STATUS_APP_VALID_LOADED BIT(4)
47 /*
48 * Value of FW_MODE bit of STATUS register describes the sensor's state:
49 * 0: Firmware is in boot mode, this allows new firmware to be loaded
50 * 1: Firmware is in application mode. CCS811 is ready to take ADC measurements
51 */
52 #define CCS811_STATUS_FW_MODE_MASK BIT(7)
53 #define CCS811_STATUS_FW_MODE_APPLICATION BIT(7)
54
55 /* Measurement modes */
56 #define CCS811_MODE_IDLE 0x00
57 #define CCS811_MODE_IAQ_1SEC 0x10
58 #define CCS811_MODE_IAQ_10SEC 0x20
59 #define CCS811_MODE_IAQ_60SEC 0x30
60 #define CCS811_MODE_RAW_DATA 0x40
61
62 #define CCS811_MEAS_MODE_INTERRUPT BIT(3)
63
64 #define CCS811_VOLTAGE_MASK 0x3FF
65
66 struct ccs811_reading {
67 __be16 co2;
68 __be16 voc;
69 u8 status;
70 u8 error;
71 __be16 raw_data;
72 } __attribute__((__packed__));
73
74 struct ccs811_data {
75 struct i2c_client *client;
76 struct mutex lock; /* Protect readings */
77 struct ccs811_reading buffer;
78 struct iio_trigger *drdy_trig;
79 struct gpio_desc *wakeup_gpio;
80 bool drdy_trig_on;
81 /* Ensures correct alignment of timestamp if present */
82 struct {
83 s16 channels[2];
84 s64 ts __aligned(8);
85 } scan;
86 };
87
88 static const struct iio_chan_spec ccs811_channels[] = {
89 {
90 .type = IIO_CURRENT,
91 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
92 BIT(IIO_CHAN_INFO_SCALE),
93 .scan_index = -1,
94 }, {
95 .type = IIO_VOLTAGE,
96 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
97 BIT(IIO_CHAN_INFO_SCALE),
98 .scan_index = -1,
99 }, {
100 .type = IIO_CONCENTRATION,
101 .channel2 = IIO_MOD_CO2,
102 .modified = 1,
103 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
104 BIT(IIO_CHAN_INFO_SCALE),
105 .scan_index = 0,
106 .scan_type = {
107 .sign = 'u',
108 .realbits = 16,
109 .storagebits = 16,
110 .endianness = IIO_BE,
111 },
112 }, {
113 .type = IIO_CONCENTRATION,
114 .channel2 = IIO_MOD_VOC,
115 .modified = 1,
116 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
117 BIT(IIO_CHAN_INFO_SCALE),
118 .scan_index = 1,
119 .scan_type = {
120 .sign = 'u',
121 .realbits = 16,
122 .storagebits = 16,
123 .endianness = IIO_BE,
124 },
125 },
126 IIO_CHAN_SOFT_TIMESTAMP(2),
127 };
128
129 /*
130 * The CCS811 powers-up in boot mode. A setup write to CCS811_APP_START will
131 * transition the sensor to application mode.
132 */
ccs811_start_sensor_application(struct i2c_client * client)133 static int ccs811_start_sensor_application(struct i2c_client *client)
134 {
135 int ret;
136
137 ret = i2c_smbus_read_byte_data(client, CCS811_STATUS);
138 if (ret < 0)
139 return ret;
140
141 if ((ret & CCS811_STATUS_FW_MODE_APPLICATION))
142 return 0;
143
144 if ((ret & CCS811_STATUS_APP_VALID_MASK) !=
145 CCS811_STATUS_APP_VALID_LOADED)
146 return -EIO;
147
148 ret = i2c_smbus_write_byte(client, CCS811_APP_START);
149 if (ret < 0)
150 return ret;
151
152 ret = i2c_smbus_read_byte_data(client, CCS811_STATUS);
153 if (ret < 0)
154 return ret;
155
156 if ((ret & CCS811_STATUS_FW_MODE_MASK) !=
157 CCS811_STATUS_FW_MODE_APPLICATION) {
158 dev_err(&client->dev, "Application failed to start. Sensor is still in boot mode.\n");
159 return -EIO;
160 }
161
162 return 0;
163 }
164
ccs811_setup(struct i2c_client * client)165 static int ccs811_setup(struct i2c_client *client)
166 {
167 int ret;
168
169 ret = ccs811_start_sensor_application(client);
170 if (ret < 0)
171 return ret;
172
173 return i2c_smbus_write_byte_data(client, CCS811_MEAS_MODE,
174 CCS811_MODE_IAQ_1SEC);
175 }
176
ccs811_set_wakeup(struct ccs811_data * data,bool enable)177 static void ccs811_set_wakeup(struct ccs811_data *data, bool enable)
178 {
179 if (!data->wakeup_gpio)
180 return;
181
182 gpiod_set_value(data->wakeup_gpio, enable);
183
184 if (enable)
185 usleep_range(50, 60);
186 else
187 usleep_range(20, 30);
188 }
189
ccs811_get_measurement(struct ccs811_data * data)190 static int ccs811_get_measurement(struct ccs811_data *data)
191 {
192 int ret, tries = 11;
193
194 ccs811_set_wakeup(data, true);
195
196 /* Maximum waiting time: 1s, as measurements are made every second */
197 while (tries-- > 0) {
198 ret = i2c_smbus_read_byte_data(data->client, CCS811_STATUS);
199 if (ret < 0)
200 return ret;
201
202 if ((ret & CCS811_STATUS_DATA_READY) || tries == 0)
203 break;
204 msleep(100);
205 }
206 if (!(ret & CCS811_STATUS_DATA_READY))
207 return -EIO;
208
209 ret = i2c_smbus_read_i2c_block_data(data->client,
210 CCS811_ALG_RESULT_DATA, 8,
211 (char *)&data->buffer);
212 ccs811_set_wakeup(data, false);
213
214 return ret;
215 }
216
ccs811_read_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int * val,int * val2,long mask)217 static int ccs811_read_raw(struct iio_dev *indio_dev,
218 struct iio_chan_spec const *chan,
219 int *val, int *val2, long mask)
220 {
221 struct ccs811_data *data = iio_priv(indio_dev);
222 int ret;
223
224 switch (mask) {
225 case IIO_CHAN_INFO_RAW:
226 ret = iio_device_claim_direct_mode(indio_dev);
227 if (ret)
228 return ret;
229 mutex_lock(&data->lock);
230 ret = ccs811_get_measurement(data);
231 if (ret < 0) {
232 mutex_unlock(&data->lock);
233 iio_device_release_direct_mode(indio_dev);
234 return ret;
235 }
236
237 switch (chan->type) {
238 case IIO_VOLTAGE:
239 *val = be16_to_cpu(data->buffer.raw_data) &
240 CCS811_VOLTAGE_MASK;
241 ret = IIO_VAL_INT;
242 break;
243 case IIO_CURRENT:
244 *val = be16_to_cpu(data->buffer.raw_data) >> 10;
245 ret = IIO_VAL_INT;
246 break;
247 case IIO_CONCENTRATION:
248 switch (chan->channel2) {
249 case IIO_MOD_CO2:
250 *val = be16_to_cpu(data->buffer.co2);
251 ret = IIO_VAL_INT;
252 break;
253 case IIO_MOD_VOC:
254 *val = be16_to_cpu(data->buffer.voc);
255 ret = IIO_VAL_INT;
256 break;
257 default:
258 ret = -EINVAL;
259 }
260 break;
261 default:
262 ret = -EINVAL;
263 }
264 mutex_unlock(&data->lock);
265 iio_device_release_direct_mode(indio_dev);
266
267 return ret;
268
269 case IIO_CHAN_INFO_SCALE:
270 switch (chan->type) {
271 case IIO_VOLTAGE:
272 *val = 1;
273 *val2 = 612903;
274 return IIO_VAL_INT_PLUS_MICRO;
275 case IIO_CURRENT:
276 *val = 0;
277 *val2 = 1000;
278 return IIO_VAL_INT_PLUS_MICRO;
279 case IIO_CONCENTRATION:
280 switch (chan->channel2) {
281 case IIO_MOD_CO2:
282 *val = 0;
283 *val2 = 100;
284 return IIO_VAL_INT_PLUS_MICRO;
285 case IIO_MOD_VOC:
286 *val = 0;
287 *val2 = 100;
288 return IIO_VAL_INT_PLUS_NANO;
289 default:
290 return -EINVAL;
291 }
292 default:
293 return -EINVAL;
294 }
295 default:
296 return -EINVAL;
297 }
298 }
299
300 static const struct iio_info ccs811_info = {
301 .read_raw = ccs811_read_raw,
302 };
303
ccs811_set_trigger_state(struct iio_trigger * trig,bool state)304 static int ccs811_set_trigger_state(struct iio_trigger *trig,
305 bool state)
306 {
307 struct iio_dev *indio_dev = iio_trigger_get_drvdata(trig);
308 struct ccs811_data *data = iio_priv(indio_dev);
309 int ret;
310
311 ret = i2c_smbus_read_byte_data(data->client, CCS811_MEAS_MODE);
312 if (ret < 0)
313 return ret;
314
315 if (state)
316 ret |= CCS811_MEAS_MODE_INTERRUPT;
317 else
318 ret &= ~CCS811_MEAS_MODE_INTERRUPT;
319
320 data->drdy_trig_on = state;
321
322 return i2c_smbus_write_byte_data(data->client, CCS811_MEAS_MODE, ret);
323 }
324
325 static const struct iio_trigger_ops ccs811_trigger_ops = {
326 .set_trigger_state = ccs811_set_trigger_state,
327 };
328
ccs811_trigger_handler(int irq,void * p)329 static irqreturn_t ccs811_trigger_handler(int irq, void *p)
330 {
331 struct iio_poll_func *pf = p;
332 struct iio_dev *indio_dev = pf->indio_dev;
333 struct ccs811_data *data = iio_priv(indio_dev);
334 struct i2c_client *client = data->client;
335 int ret;
336
337 ret = i2c_smbus_read_i2c_block_data(client, CCS811_ALG_RESULT_DATA,
338 sizeof(data->scan.channels),
339 (u8 *)data->scan.channels);
340 if (ret != 4) {
341 dev_err(&client->dev, "cannot read sensor data\n");
342 goto err;
343 }
344
345 iio_push_to_buffers_with_timestamp(indio_dev, &data->scan,
346 iio_get_time_ns(indio_dev));
347
348 err:
349 iio_trigger_notify_done(indio_dev->trig);
350
351 return IRQ_HANDLED;
352 }
353
ccs811_data_rdy_trigger_poll(int irq,void * private)354 static irqreturn_t ccs811_data_rdy_trigger_poll(int irq, void *private)
355 {
356 struct iio_dev *indio_dev = private;
357 struct ccs811_data *data = iio_priv(indio_dev);
358
359 if (data->drdy_trig_on)
360 iio_trigger_poll(data->drdy_trig);
361
362 return IRQ_HANDLED;
363 }
364
ccs811_reset(struct i2c_client * client)365 static int ccs811_reset(struct i2c_client *client)
366 {
367 struct gpio_desc *reset_gpio;
368 int ret;
369
370 reset_gpio = devm_gpiod_get_optional(&client->dev, "reset",
371 GPIOD_OUT_LOW);
372 if (IS_ERR(reset_gpio))
373 return PTR_ERR(reset_gpio);
374
375 /* Try to reset using nRESET pin if available else do SW reset */
376 if (reset_gpio) {
377 gpiod_set_value(reset_gpio, 1);
378 usleep_range(20, 30);
379 gpiod_set_value(reset_gpio, 0);
380 } else {
381 /*
382 * As per the datasheet, this sequence of values needs to be
383 * written to the SW_RESET register for triggering the soft
384 * reset in the device and placing it in boot mode.
385 */
386 static const u8 reset_seq[] = {
387 0x11, 0xE5, 0x72, 0x8A,
388 };
389
390 ret = i2c_smbus_write_i2c_block_data(client, CCS811_SW_RESET,
391 sizeof(reset_seq), reset_seq);
392 if (ret < 0) {
393 dev_err(&client->dev, "Failed to reset sensor\n");
394 return ret;
395 }
396 }
397
398 /* tSTART delay required after reset */
399 usleep_range(1000, 2000);
400
401 return 0;
402 }
403
ccs811_probe(struct i2c_client * client,const struct i2c_device_id * id)404 static int ccs811_probe(struct i2c_client *client,
405 const struct i2c_device_id *id)
406 {
407 struct iio_dev *indio_dev;
408 struct ccs811_data *data;
409 int ret;
410
411 if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_WRITE_BYTE
412 | I2C_FUNC_SMBUS_BYTE_DATA
413 | I2C_FUNC_SMBUS_READ_I2C_BLOCK))
414 return -EOPNOTSUPP;
415
416 indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
417 if (!indio_dev)
418 return -ENOMEM;
419
420 data = iio_priv(indio_dev);
421 i2c_set_clientdata(client, indio_dev);
422 data->client = client;
423
424 data->wakeup_gpio = devm_gpiod_get_optional(&client->dev, "wakeup",
425 GPIOD_OUT_HIGH);
426 if (IS_ERR(data->wakeup_gpio))
427 return PTR_ERR(data->wakeup_gpio);
428
429 ccs811_set_wakeup(data, true);
430
431 ret = ccs811_reset(client);
432 if (ret) {
433 ccs811_set_wakeup(data, false);
434 return ret;
435 }
436
437 /* Check hardware id (should be 0x81 for this family of devices) */
438 ret = i2c_smbus_read_byte_data(client, CCS811_HW_ID);
439 if (ret < 0) {
440 ccs811_set_wakeup(data, false);
441 return ret;
442 }
443
444 if (ret != CCS811_HW_ID_VALUE) {
445 dev_err(&client->dev, "hardware id doesn't match CCS81x\n");
446 ccs811_set_wakeup(data, false);
447 return -ENODEV;
448 }
449
450 ret = i2c_smbus_read_byte_data(client, CCS811_HW_VERSION);
451 if (ret < 0) {
452 ccs811_set_wakeup(data, false);
453 return ret;
454 }
455
456 if ((ret & CCS811_HW_VERSION_MASK) != CCS811_HW_VERSION_VALUE) {
457 dev_err(&client->dev, "no CCS811 sensor\n");
458 ccs811_set_wakeup(data, false);
459 return -ENODEV;
460 }
461
462 ret = ccs811_setup(client);
463 if (ret < 0) {
464 ccs811_set_wakeup(data, false);
465 return ret;
466 }
467
468 ccs811_set_wakeup(data, false);
469
470 mutex_init(&data->lock);
471
472 indio_dev->name = id->name;
473 indio_dev->info = &ccs811_info;
474 indio_dev->modes = INDIO_DIRECT_MODE;
475
476 indio_dev->channels = ccs811_channels;
477 indio_dev->num_channels = ARRAY_SIZE(ccs811_channels);
478
479 if (client->irq > 0) {
480 ret = devm_request_threaded_irq(&client->dev, client->irq,
481 ccs811_data_rdy_trigger_poll,
482 NULL,
483 IRQF_TRIGGER_FALLING |
484 IRQF_ONESHOT,
485 "ccs811_irq", indio_dev);
486 if (ret) {
487 dev_err(&client->dev, "irq request error %d\n", -ret);
488 goto err_poweroff;
489 }
490
491 data->drdy_trig = devm_iio_trigger_alloc(&client->dev,
492 "%s-dev%d",
493 indio_dev->name,
494 iio_device_id(indio_dev));
495 if (!data->drdy_trig) {
496 ret = -ENOMEM;
497 goto err_poweroff;
498 }
499
500 data->drdy_trig->ops = &ccs811_trigger_ops;
501 iio_trigger_set_drvdata(data->drdy_trig, indio_dev);
502 ret = iio_trigger_register(data->drdy_trig);
503 if (ret)
504 goto err_poweroff;
505
506 indio_dev->trig = iio_trigger_get(data->drdy_trig);
507 }
508
509 ret = iio_triggered_buffer_setup(indio_dev, NULL,
510 ccs811_trigger_handler, NULL);
511
512 if (ret < 0) {
513 dev_err(&client->dev, "triggered buffer setup failed\n");
514 goto err_trigger_unregister;
515 }
516
517 ret = iio_device_register(indio_dev);
518 if (ret < 0) {
519 dev_err(&client->dev, "unable to register iio device\n");
520 goto err_buffer_cleanup;
521 }
522 return 0;
523
524 err_buffer_cleanup:
525 iio_triggered_buffer_cleanup(indio_dev);
526 err_trigger_unregister:
527 if (data->drdy_trig)
528 iio_trigger_unregister(data->drdy_trig);
529 err_poweroff:
530 i2c_smbus_write_byte_data(client, CCS811_MEAS_MODE, CCS811_MODE_IDLE);
531
532 return ret;
533 }
534
ccs811_remove(struct i2c_client * client)535 static void ccs811_remove(struct i2c_client *client)
536 {
537 struct iio_dev *indio_dev = i2c_get_clientdata(client);
538 struct ccs811_data *data = iio_priv(indio_dev);
539 int ret;
540
541 iio_device_unregister(indio_dev);
542 iio_triggered_buffer_cleanup(indio_dev);
543 if (data->drdy_trig)
544 iio_trigger_unregister(data->drdy_trig);
545
546 ret = i2c_smbus_write_byte_data(client, CCS811_MEAS_MODE,
547 CCS811_MODE_IDLE);
548 if (ret)
549 dev_warn(&client->dev, "Failed to power down device (%pe)\n",
550 ERR_PTR(ret));
551 }
552
553 static const struct i2c_device_id ccs811_id[] = {
554 {"ccs811", 0},
555 { }
556 };
557 MODULE_DEVICE_TABLE(i2c, ccs811_id);
558
559 static const struct of_device_id ccs811_dt_ids[] = {
560 { .compatible = "ams,ccs811" },
561 { }
562 };
563 MODULE_DEVICE_TABLE(of, ccs811_dt_ids);
564
565 static struct i2c_driver ccs811_driver = {
566 .driver = {
567 .name = "ccs811",
568 .of_match_table = ccs811_dt_ids,
569 },
570 .probe = ccs811_probe,
571 .remove = ccs811_remove,
572 .id_table = ccs811_id,
573 };
574 module_i2c_driver(ccs811_driver);
575
576 MODULE_AUTHOR("Narcisa Vasile <narcisaanamaria12@gmail.com>");
577 MODULE_DESCRIPTION("CCS811 volatile organic compounds sensor");
578 MODULE_LICENSE("GPL v2");
579