xref: /openbmc/linux/drivers/iio/chemical/sgp30.c (revision 7cf15f42)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * sgp30.c - Support for Sensirion SGP Gas Sensors
4  *
5  * Copyright (C) 2018 Andreas Brauchli <andreas.brauchli@sensirion.com>
6  *
7  * I2C slave address: 0x58
8  *
9  * Datasheets:
10  * https://www.sensirion.com/file/datasheet_sgp30
11  * https://www.sensirion.com/file/datasheet_sgpc3
12  *
13  * TODO:
14  * - baseline support
15  * - humidity compensation
16  * - power mode switching (SGPC3)
17  */
18 
19 #include <linux/crc8.h>
20 #include <linux/delay.h>
21 #include <linux/kthread.h>
22 #include <linux/module.h>
23 #include <linux/mod_devicetable.h>
24 #include <linux/mutex.h>
25 #include <linux/i2c.h>
26 #include <linux/iio/iio.h>
27 #include <linux/iio/sysfs.h>
28 
29 #define SGP_WORD_LEN				2
30 #define SGP_CRC8_POLYNOMIAL			0x31
31 #define SGP_CRC8_INIT				0xff
32 #define SGP_CRC8_LEN				1
33 #define SGP_CMD(cmd_word)			cpu_to_be16(cmd_word)
34 #define SGP_CMD_DURATION_US			12000
35 #define SGP_MEASUREMENT_DURATION_US		50000
36 #define SGP_CMD_LEN				SGP_WORD_LEN
37 #define SGP_CMD_MAX_BUF_SIZE			(SGP_CMD_LEN + 2 * SGP_WORD_LEN)
38 #define SGP_MEASUREMENT_LEN			2
39 #define SGP30_MEASURE_INTERVAL_HZ		1
40 #define SGPC3_MEASURE_INTERVAL_HZ		2
41 #define SGP_VERS_PRODUCT(data)	((((data)->feature_set) & 0xf000) >> 12)
42 #define SGP_VERS_RESERVED(data)	((((data)->feature_set) & 0x0800) >> 11)
43 #define SGP_VERS_GEN(data)	((((data)->feature_set) & 0x0600) >> 9)
44 #define SGP_VERS_ENG_BIT(data)	((((data)->feature_set) & 0x0100) >> 8)
45 #define SGP_VERS_MAJOR(data)	((((data)->feature_set) & 0x00e0) >> 5)
46 #define SGP_VERS_MINOR(data)	(((data)->feature_set) & 0x001f)
47 
48 DECLARE_CRC8_TABLE(sgp_crc8_table);
49 
50 enum sgp_product_id {
51 	SGP30 = 0,
52 	SGPC3,
53 };
54 
55 enum sgp30_channel_idx {
56 	SGP30_IAQ_TVOC_IDX = 0,
57 	SGP30_IAQ_CO2EQ_IDX,
58 	SGP30_SIG_ETOH_IDX,
59 	SGP30_SIG_H2_IDX,
60 };
61 
62 enum sgpc3_channel_idx {
63 	SGPC3_IAQ_TVOC_IDX = 10,
64 	SGPC3_SIG_ETOH_IDX,
65 };
66 
67 enum sgp_cmd {
68 	SGP_CMD_IAQ_INIT			= SGP_CMD(0x2003),
69 	SGP_CMD_IAQ_MEASURE			= SGP_CMD(0x2008),
70 	SGP_CMD_GET_FEATURE_SET			= SGP_CMD(0x202f),
71 	SGP_CMD_GET_SERIAL_ID			= SGP_CMD(0x3682),
72 
73 	SGP30_CMD_MEASURE_SIGNAL		= SGP_CMD(0x2050),
74 
75 	SGPC3_CMD_MEASURE_RAW			= SGP_CMD(0x2046),
76 };
77 
78 struct sgp_version {
79 	u8 major;
80 	u8 minor;
81 };
82 
83 struct sgp_crc_word {
84 	__be16 value;
85 	u8 crc8;
86 } __attribute__((__packed__));
87 
88 union sgp_reading {
89 	u8 start;
90 	struct sgp_crc_word raw_words[4];
91 };
92 
93 enum _iaq_buffer_state {
94 	IAQ_BUFFER_EMPTY = 0,
95 	IAQ_BUFFER_DEFAULT_VALS,
96 	IAQ_BUFFER_VALID,
97 };
98 
99 struct sgp_data {
100 	struct i2c_client *client;
101 	struct task_struct *iaq_thread;
102 	struct mutex data_lock;
103 	unsigned long iaq_init_start_jiffies;
104 	unsigned long iaq_defval_skip_jiffies;
105 	u16 product_id;
106 	u16 feature_set;
107 	unsigned long measure_interval_jiffies;
108 	enum sgp_cmd iaq_init_cmd;
109 	enum sgp_cmd measure_iaq_cmd;
110 	enum sgp_cmd measure_gas_signals_cmd;
111 	union sgp_reading buffer;
112 	union sgp_reading iaq_buffer;
113 	enum _iaq_buffer_state iaq_buffer_state;
114 };
115 
116 struct sgp_device {
117 	const struct iio_chan_spec *channels;
118 	int num_channels;
119 };
120 
121 static const struct sgp_version supported_versions_sgp30[] = {
122 	{
123 		.major = 1,
124 		.minor = 0,
125 	},
126 };
127 
128 static const struct sgp_version supported_versions_sgpc3[] = {
129 	{
130 		.major = 0,
131 		.minor = 4,
132 	},
133 };
134 
135 static const struct iio_chan_spec sgp30_channels[] = {
136 	{
137 		.type = IIO_CONCENTRATION,
138 		.channel2 = IIO_MOD_VOC,
139 		.modified = 1,
140 		.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
141 		.address = SGP30_IAQ_TVOC_IDX,
142 	},
143 	{
144 		.type = IIO_CONCENTRATION,
145 		.channel2 = IIO_MOD_CO2,
146 		.modified = 1,
147 		.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
148 		.address = SGP30_IAQ_CO2EQ_IDX,
149 	},
150 	{
151 		.type = IIO_CONCENTRATION,
152 		.channel2 = IIO_MOD_ETHANOL,
153 		.modified = 1,
154 		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
155 		.address = SGP30_SIG_ETOH_IDX,
156 	},
157 	{
158 		.type = IIO_CONCENTRATION,
159 		.channel2 = IIO_MOD_H2,
160 		.modified = 1,
161 		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
162 		.address = SGP30_SIG_H2_IDX,
163 	},
164 };
165 
166 static const struct iio_chan_spec sgpc3_channels[] = {
167 	{
168 		.type = IIO_CONCENTRATION,
169 		.channel2 = IIO_MOD_VOC,
170 		.modified = 1,
171 		.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
172 		.address = SGPC3_IAQ_TVOC_IDX,
173 	},
174 	{
175 		.type = IIO_CONCENTRATION,
176 		.channel2 = IIO_MOD_ETHANOL,
177 		.modified = 1,
178 		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
179 		.address = SGPC3_SIG_ETOH_IDX,
180 	},
181 };
182 
183 static const struct sgp_device sgp_devices[] = {
184 	[SGP30] = {
185 		.channels = sgp30_channels,
186 		.num_channels = ARRAY_SIZE(sgp30_channels),
187 	},
188 	[SGPC3] = {
189 		.channels = sgpc3_channels,
190 		.num_channels = ARRAY_SIZE(sgpc3_channels),
191 	},
192 };
193 
194 /**
195  * sgp_verify_buffer() - verify the checksums of the data buffer words
196  *
197  * @data:       SGP data
198  * @buf:        Raw data buffer
199  * @word_count: Num data words stored in the buffer, excluding CRC bytes
200  *
201  * Return:      0 on success, negative error otherwise.
202  */
sgp_verify_buffer(const struct sgp_data * data,union sgp_reading * buf,size_t word_count)203 static int sgp_verify_buffer(const struct sgp_data *data,
204 			     union sgp_reading *buf, size_t word_count)
205 {
206 	size_t size = word_count * (SGP_WORD_LEN + SGP_CRC8_LEN);
207 	int i;
208 	u8 crc;
209 	u8 *data_buf = &buf->start;
210 
211 	for (i = 0; i < size; i += SGP_WORD_LEN + SGP_CRC8_LEN) {
212 		crc = crc8(sgp_crc8_table, &data_buf[i], SGP_WORD_LEN,
213 			   SGP_CRC8_INIT);
214 		if (crc != data_buf[i + SGP_WORD_LEN]) {
215 			dev_err(&data->client->dev, "CRC error\n");
216 			return -EIO;
217 		}
218 	}
219 
220 	return 0;
221 }
222 
223 /**
224  * sgp_read_cmd() - reads data from sensor after issuing a command
225  * The caller must hold data->data_lock for the duration of the call.
226  * @data:        SGP data
227  * @cmd:         SGP Command to issue
228  * @buf:         Raw data buffer to use
229  * @word_count:  Num words to read, excluding CRC bytes
230  * @duration_us: Time taken to sensor to take a reading and data to be ready.
231  *
232  * Return:       0 on success, negative error otherwise.
233  */
sgp_read_cmd(struct sgp_data * data,enum sgp_cmd cmd,union sgp_reading * buf,size_t word_count,unsigned long duration_us)234 static int sgp_read_cmd(struct sgp_data *data, enum sgp_cmd cmd,
235 			union sgp_reading *buf, size_t word_count,
236 			unsigned long duration_us)
237 {
238 	int ret;
239 	struct i2c_client *client = data->client;
240 	size_t size = word_count * (SGP_WORD_LEN + SGP_CRC8_LEN);
241 	u8 *data_buf;
242 
243 	ret = i2c_master_send(client, (const char *)&cmd, SGP_CMD_LEN);
244 	if (ret != SGP_CMD_LEN)
245 		return -EIO;
246 	usleep_range(duration_us, duration_us + 1000);
247 
248 	if (word_count == 0)
249 		return 0;
250 
251 	data_buf = &buf->start;
252 	ret = i2c_master_recv(client, data_buf, size);
253 	if (ret < 0)
254 		return ret;
255 	if (ret != size)
256 		return -EIO;
257 
258 	return sgp_verify_buffer(data, buf, word_count);
259 }
260 
261 /**
262  * sgp_measure_iaq() - measure and retrieve IAQ values from sensor
263  * The caller must hold data->data_lock for the duration of the call.
264  * @data:       SGP data
265  *
266  * Return:      0 on success, -EBUSY on default values, negative error
267  *              otherwise.
268  */
269 
sgp_measure_iaq(struct sgp_data * data)270 static int sgp_measure_iaq(struct sgp_data *data)
271 {
272 	int ret;
273 	/* data contains default values */
274 	bool default_vals = !time_after(jiffies, data->iaq_init_start_jiffies +
275 						 data->iaq_defval_skip_jiffies);
276 
277 	ret = sgp_read_cmd(data, data->measure_iaq_cmd, &data->iaq_buffer,
278 			   SGP_MEASUREMENT_LEN, SGP_MEASUREMENT_DURATION_US);
279 	if (ret < 0)
280 		return ret;
281 
282 	data->iaq_buffer_state = IAQ_BUFFER_DEFAULT_VALS;
283 
284 	if (default_vals)
285 		return -EBUSY;
286 
287 	data->iaq_buffer_state = IAQ_BUFFER_VALID;
288 
289 	return 0;
290 }
291 
sgp_iaq_thread_sleep_until(const struct sgp_data * data,unsigned long sleep_jiffies)292 static void sgp_iaq_thread_sleep_until(const struct sgp_data *data,
293 				       unsigned long sleep_jiffies)
294 {
295 	const long IAQ_POLL = 50000;
296 
297 	while (!time_after(jiffies, sleep_jiffies)) {
298 		usleep_range(IAQ_POLL, IAQ_POLL + 10000);
299 		if (kthread_should_stop() || data->iaq_init_start_jiffies == 0)
300 			return;
301 	}
302 }
303 
sgp_iaq_threadfn(void * p)304 static int sgp_iaq_threadfn(void *p)
305 {
306 	struct sgp_data *data = (struct sgp_data *)p;
307 	unsigned long next_update_jiffies;
308 	int ret;
309 
310 	while (!kthread_should_stop()) {
311 		mutex_lock(&data->data_lock);
312 		if (data->iaq_init_start_jiffies == 0) {
313 			ret = sgp_read_cmd(data, data->iaq_init_cmd, NULL, 0,
314 					   SGP_CMD_DURATION_US);
315 			if (ret < 0)
316 				goto unlock_sleep_continue;
317 			data->iaq_init_start_jiffies = jiffies;
318 		}
319 
320 		ret = sgp_measure_iaq(data);
321 		if (ret && ret != -EBUSY) {
322 			dev_warn(&data->client->dev,
323 				 "IAQ measurement error [%d]\n", ret);
324 		}
325 unlock_sleep_continue:
326 		next_update_jiffies = jiffies + data->measure_interval_jiffies;
327 		mutex_unlock(&data->data_lock);
328 		sgp_iaq_thread_sleep_until(data, next_update_jiffies);
329 	}
330 
331 	return 0;
332 }
333 
sgp_read_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int * val,int * val2,long mask)334 static int sgp_read_raw(struct iio_dev *indio_dev,
335 			struct iio_chan_spec const *chan, int *val,
336 			int *val2, long mask)
337 {
338 	struct sgp_data *data = iio_priv(indio_dev);
339 	struct sgp_crc_word *words;
340 	int ret;
341 
342 	switch (mask) {
343 	case IIO_CHAN_INFO_PROCESSED:
344 		mutex_lock(&data->data_lock);
345 		if (data->iaq_buffer_state != IAQ_BUFFER_VALID) {
346 			mutex_unlock(&data->data_lock);
347 			return -EBUSY;
348 		}
349 		words = data->iaq_buffer.raw_words;
350 		switch (chan->address) {
351 		case SGP30_IAQ_TVOC_IDX:
352 		case SGPC3_IAQ_TVOC_IDX:
353 			*val = 0;
354 			*val2 = be16_to_cpu(words[1].value);
355 			ret = IIO_VAL_INT_PLUS_NANO;
356 			break;
357 		case SGP30_IAQ_CO2EQ_IDX:
358 			*val = 0;
359 			*val2 = be16_to_cpu(words[0].value);
360 			ret = IIO_VAL_INT_PLUS_MICRO;
361 			break;
362 		default:
363 			ret = -EINVAL;
364 			break;
365 		}
366 		mutex_unlock(&data->data_lock);
367 		break;
368 	case IIO_CHAN_INFO_RAW:
369 		mutex_lock(&data->data_lock);
370 		if (chan->address == SGPC3_SIG_ETOH_IDX) {
371 			if (data->iaq_buffer_state == IAQ_BUFFER_EMPTY)
372 				ret = -EBUSY;
373 			else
374 				ret = 0;
375 			words = data->iaq_buffer.raw_words;
376 		} else {
377 			ret = sgp_read_cmd(data, data->measure_gas_signals_cmd,
378 					   &data->buffer, SGP_MEASUREMENT_LEN,
379 					   SGP_MEASUREMENT_DURATION_US);
380 			words = data->buffer.raw_words;
381 		}
382 		if (ret) {
383 			mutex_unlock(&data->data_lock);
384 			return ret;
385 		}
386 
387 		switch (chan->address) {
388 		case SGP30_SIG_ETOH_IDX:
389 			*val = be16_to_cpu(words[1].value);
390 			ret = IIO_VAL_INT;
391 			break;
392 		case SGPC3_SIG_ETOH_IDX:
393 		case SGP30_SIG_H2_IDX:
394 			*val = be16_to_cpu(words[0].value);
395 			ret = IIO_VAL_INT;
396 			break;
397 		default:
398 			ret = -EINVAL;
399 			break;
400 		}
401 		mutex_unlock(&data->data_lock);
402 		break;
403 	default:
404 		return -EINVAL;
405 	}
406 
407 	return ret;
408 }
409 
sgp_check_compat(struct sgp_data * data,unsigned int product_id)410 static int sgp_check_compat(struct sgp_data *data,
411 			    unsigned int product_id)
412 {
413 	struct device *dev = &data->client->dev;
414 	const struct sgp_version *supported_versions;
415 	u16 ix, num_fs;
416 	u16 product, generation, major, minor;
417 
418 	/* driver does not match product */
419 	generation = SGP_VERS_GEN(data);
420 	if (generation != 0) {
421 		dev_err(dev,
422 			"incompatible product generation %d != 0", generation);
423 		return -ENODEV;
424 	}
425 
426 	product = SGP_VERS_PRODUCT(data);
427 	if (product != product_id) {
428 		dev_err(dev, "sensor reports a different product: 0x%04x\n",
429 			product);
430 		return -ENODEV;
431 	}
432 
433 	if (SGP_VERS_RESERVED(data))
434 		dev_warn(dev, "reserved bit is set\n");
435 
436 	/* engineering samples are not supported: no interface guarantees */
437 	if (SGP_VERS_ENG_BIT(data))
438 		return -ENODEV;
439 
440 	switch (product) {
441 	case SGP30:
442 		supported_versions = supported_versions_sgp30;
443 		num_fs = ARRAY_SIZE(supported_versions_sgp30);
444 		break;
445 	case SGPC3:
446 		supported_versions = supported_versions_sgpc3;
447 		num_fs = ARRAY_SIZE(supported_versions_sgpc3);
448 		break;
449 	default:
450 		return -ENODEV;
451 	}
452 
453 	major = SGP_VERS_MAJOR(data);
454 	minor = SGP_VERS_MINOR(data);
455 	for (ix = 0; ix < num_fs; ix++) {
456 		if (major == supported_versions[ix].major &&
457 		    minor >= supported_versions[ix].minor)
458 			return 0;
459 	}
460 	dev_err(dev, "unsupported sgp version: %d.%d\n", major, minor);
461 
462 	return -ENODEV;
463 }
464 
sgp_init(struct sgp_data * data)465 static void sgp_init(struct sgp_data *data)
466 {
467 	data->iaq_init_cmd = SGP_CMD_IAQ_INIT;
468 	data->iaq_init_start_jiffies = 0;
469 	data->iaq_buffer_state = IAQ_BUFFER_EMPTY;
470 	switch (SGP_VERS_PRODUCT(data)) {
471 	case SGP30:
472 		data->measure_interval_jiffies = SGP30_MEASURE_INTERVAL_HZ * HZ;
473 		data->measure_iaq_cmd = SGP_CMD_IAQ_MEASURE;
474 		data->measure_gas_signals_cmd = SGP30_CMD_MEASURE_SIGNAL;
475 		data->product_id = SGP30;
476 		data->iaq_defval_skip_jiffies = 15 * HZ;
477 		break;
478 	case SGPC3:
479 		data->measure_interval_jiffies = SGPC3_MEASURE_INTERVAL_HZ * HZ;
480 		data->measure_iaq_cmd = SGPC3_CMD_MEASURE_RAW;
481 		data->measure_gas_signals_cmd = SGPC3_CMD_MEASURE_RAW;
482 		data->product_id = SGPC3;
483 		data->iaq_defval_skip_jiffies =
484 			43 * data->measure_interval_jiffies;
485 		break;
486 	}
487 }
488 
489 static const struct iio_info sgp_info = {
490 	.read_raw	= sgp_read_raw,
491 };
492 
493 static const struct of_device_id sgp_dt_ids[] = {
494 	{ .compatible = "sensirion,sgp30", .data = (void *)SGP30 },
495 	{ .compatible = "sensirion,sgpc3", .data = (void *)SGPC3 },
496 	{ }
497 };
498 
sgp_probe(struct i2c_client * client)499 static int sgp_probe(struct i2c_client *client)
500 {
501 	const struct i2c_device_id *id = i2c_client_get_device_id(client);
502 	struct device *dev = &client->dev;
503 	struct iio_dev *indio_dev;
504 	struct sgp_data *data;
505 	unsigned long product_id;
506 	int ret;
507 
508 	indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
509 	if (!indio_dev)
510 		return -ENOMEM;
511 
512 	if (dev_fwnode(dev))
513 		product_id = (unsigned long)device_get_match_data(dev);
514 	else
515 		product_id = id->driver_data;
516 
517 	data = iio_priv(indio_dev);
518 	i2c_set_clientdata(client, indio_dev);
519 	data->client = client;
520 	crc8_populate_msb(sgp_crc8_table, SGP_CRC8_POLYNOMIAL);
521 	mutex_init(&data->data_lock);
522 
523 	/* get feature set version and write it to client data */
524 	ret = sgp_read_cmd(data, SGP_CMD_GET_FEATURE_SET, &data->buffer, 1,
525 			   SGP_CMD_DURATION_US);
526 	if (ret < 0)
527 		return ret;
528 
529 	data->feature_set = be16_to_cpu(data->buffer.raw_words[0].value);
530 
531 	ret = sgp_check_compat(data, product_id);
532 	if (ret)
533 		return ret;
534 
535 	indio_dev->info = &sgp_info;
536 	indio_dev->name = id->name;
537 	indio_dev->modes = INDIO_DIRECT_MODE;
538 	indio_dev->channels = sgp_devices[product_id].channels;
539 	indio_dev->num_channels = sgp_devices[product_id].num_channels;
540 
541 	sgp_init(data);
542 
543 	ret = devm_iio_device_register(dev, indio_dev);
544 	if (ret) {
545 		dev_err(dev, "failed to register iio device\n");
546 		return ret;
547 	}
548 
549 	data->iaq_thread = kthread_run(sgp_iaq_threadfn, data,
550 				       "%s-iaq", data->client->name);
551 
552 	return 0;
553 }
554 
sgp_remove(struct i2c_client * client)555 static void sgp_remove(struct i2c_client *client)
556 {
557 	struct iio_dev *indio_dev = i2c_get_clientdata(client);
558 	struct sgp_data *data = iio_priv(indio_dev);
559 
560 	if (data->iaq_thread)
561 		kthread_stop(data->iaq_thread);
562 }
563 
564 static const struct i2c_device_id sgp_id[] = {
565 	{ "sgp30", SGP30 },
566 	{ "sgpc3", SGPC3 },
567 	{ }
568 };
569 
570 MODULE_DEVICE_TABLE(i2c, sgp_id);
571 MODULE_DEVICE_TABLE(of, sgp_dt_ids);
572 
573 static struct i2c_driver sgp_driver = {
574 	.driver = {
575 		.name = "sgp30",
576 		.of_match_table = sgp_dt_ids,
577 	},
578 	.probe = sgp_probe,
579 	.remove = sgp_remove,
580 	.id_table = sgp_id,
581 };
582 module_i2c_driver(sgp_driver);
583 
584 MODULE_AUTHOR("Andreas Brauchli <andreas.brauchli@sensirion.com>");
585 MODULE_AUTHOR("Pascal Sachs <pascal.sachs@sensirion.com>");
586 MODULE_DESCRIPTION("Sensirion SGP gas sensors");
587 MODULE_LICENSE("GPL v2");
588