summaryrefslogtreecommitdiff
path: root/drivers/iio/chemical/scd4x.c
blob: 37143b5526ee640c74b8b677b5a512419034ace8 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
// SPDX-License-Identifier: GPL-2.0
/*
 * Sensirion SCD4X carbon dioxide sensor i2c driver
 *
 * Copyright (C) 2021 Protonic Holland
 * Author: Roan van Dijk <roan@protonic.nl>
 *
 * I2C slave address: 0x62
 *
 * Datasheets:
 * https://www.sensirion.com/file/datasheet_scd4x
 */

#include <asm/unaligned.h>
#include <linux/crc8.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/i2c.h>
#include <linux/iio/buffer.h>
#include <linux/iio/iio.h>
#include <linux/iio/sysfs.h>
#include <linux/iio/trigger.h>
#include <linux/iio/trigger_consumer.h>
#include <linux/iio/triggered_buffer.h>
#include <linux/iio/types.h>
#include <linux/kernel.h>
#include <linux/mutex.h>
#include <linux/string.h>
#include <linux/sysfs.h>
#include <linux/types.h>

#define SCD4X_CRC8_POLYNOMIAL 0x31
#define SCD4X_TIMEOUT_ERR 1000
#define SCD4X_READ_BUF_SIZE 9
#define SCD4X_COMMAND_BUF_SIZE 2
#define SCD4X_WRITE_BUF_SIZE 5
#define SCD4X_FRC_MIN_PPM 0
#define SCD4X_FRC_MAX_PPM 2000
#define SCD4X_READY_MASK 0x01

/*Commands SCD4X*/
enum scd4x_cmd {
	CMD_START_MEAS          = 0x21b1,
	CMD_READ_MEAS           = 0xec05,
	CMD_STOP_MEAS           = 0x3f86,
	CMD_SET_TEMP_OFFSET     = 0x241d,
	CMD_GET_TEMP_OFFSET     = 0x2318,
	CMD_FRC                 = 0x362f,
	CMD_SET_ASC             = 0x2416,
	CMD_GET_ASC             = 0x2313,
	CMD_GET_DATA_READY      = 0xe4b8,
};

enum scd4x_channel_idx {
	SCD4X_CO2,
	SCD4X_TEMP,
	SCD4X_HR,
};

struct scd4x_state {
	struct i2c_client *client;
	/* maintain access to device, to prevent concurrent reads/writes */
	struct mutex lock;
	struct regulator *vdd;
};

DECLARE_CRC8_TABLE(scd4x_crc8_table);

static int scd4x_i2c_xfer(struct scd4x_state *state, char *txbuf, int txsize,
				char *rxbuf, int rxsize)
{
	struct i2c_client *client = state->client;
	int ret;

	ret = i2c_master_send(client, txbuf, txsize);

	if (ret < 0)
		return ret;
	if (ret != txsize)
		return -EIO;

	if (rxsize == 0)
		return 0;

	ret = i2c_master_recv(client, rxbuf, rxsize);
	if (ret < 0)
		return ret;
	if (ret != rxsize)
		return -EIO;

	return 0;
}

static int scd4x_send_command(struct scd4x_state *state, enum scd4x_cmd cmd)
{
	char buf[SCD4X_COMMAND_BUF_SIZE];
	int ret;

	/*
	 * Measurement needs to be stopped before sending commands.
	 * Except stop and start command.
	 */
	if ((cmd != CMD_STOP_MEAS) && (cmd != CMD_START_MEAS)) {

		ret = scd4x_send_command(state, CMD_STOP_MEAS);
		if (ret)
			return ret;

		/* execution time for stopping measurement */
		msleep_interruptible(500);
	}

	put_unaligned_be16(cmd, buf);
	ret = scd4x_i2c_xfer(state, buf, 2, buf, 0);
	if (ret)
		return ret;

	if ((cmd != CMD_STOP_MEAS) && (cmd != CMD_START_MEAS)) {
		ret = scd4x_send_command(state, CMD_START_MEAS);
		if (ret)
			return ret;
	}

	return 0;
}

static int scd4x_read(struct scd4x_state *state, enum scd4x_cmd cmd,
			void *response, int response_sz)
{
	struct i2c_client *client = state->client;
	char buf[SCD4X_READ_BUF_SIZE];
	char *rsp = response;
	int i, ret;
	char crc;

	/*
	 * Measurement needs to be stopped before sending commands.
	 * Except for reading measurement and data ready command.
	 */
	if ((cmd != CMD_GET_DATA_READY) && (cmd != CMD_READ_MEAS)) {
		ret = scd4x_send_command(state, CMD_STOP_MEAS);
		if (ret)
			return ret;

		/* execution time for stopping measurement */
		msleep_interruptible(500);
	}

	/* CRC byte for every 2 bytes of data */
	response_sz += response_sz / 2;

	put_unaligned_be16(cmd, buf);
	ret = scd4x_i2c_xfer(state, buf, 2, buf, response_sz);
	if (ret)
		return ret;

	for (i = 0; i < response_sz; i += 3) {
		crc = crc8(scd4x_crc8_table, buf + i, 2, CRC8_INIT_VALUE);
		if (crc != buf[i + 2]) {
			dev_err(&client->dev, "CRC error\n");
			return -EIO;
		}

		*rsp++ = buf[i];
		*rsp++ = buf[i + 1];
	}

	/* start measurement */
	if ((cmd != CMD_GET_DATA_READY) && (cmd != CMD_READ_MEAS)) {
		ret = scd4x_send_command(state, CMD_START_MEAS);
		if (ret)
			return ret;
	}

	return 0;
}

static int scd4x_write(struct scd4x_state *state, enum scd4x_cmd cmd, uint16_t arg)
{
	char buf[SCD4X_WRITE_BUF_SIZE];
	int ret;
	char crc;

	put_unaligned_be16(cmd, buf);
	put_unaligned_be16(arg, buf + 2);

	crc = crc8(scd4x_crc8_table, buf + 2, 2, CRC8_INIT_VALUE);
	buf[4] = crc;

	/* measurement needs to be stopped before sending commands */
	ret = scd4x_send_command(state, CMD_STOP_MEAS);
	if (ret)
		return ret;

	/* execution time */
	msleep_interruptible(500);

	ret = scd4x_i2c_xfer(state, buf, SCD4X_WRITE_BUF_SIZE, buf, 0);
	if (ret)
		return ret;

	/* start measurement, except for forced calibration command */
	if (cmd != CMD_FRC) {
		ret = scd4x_send_command(state, CMD_START_MEAS);
		if (ret)
			return ret;
	}

	return 0;
}

static int scd4x_write_and_fetch(struct scd4x_state *state, enum scd4x_cmd cmd,
				uint16_t arg, void *response, int response_sz)
{
	struct i2c_client *client = state->client;
	char buf[SCD4X_READ_BUF_SIZE];
	char *rsp = response;
	int i, ret;
	char crc;

	ret = scd4x_write(state, CMD_FRC, arg);
	if (ret)
		goto err;

	/* execution time */
	msleep_interruptible(400);

	/* CRC byte for every 2 bytes of data */
	response_sz += response_sz / 2;

	ret = i2c_master_recv(client, buf, response_sz);
	if (ret < 0)
		goto err;
	if (ret != response_sz) {
		ret = -EIO;
		goto err;
	}

	for (i = 0; i < response_sz; i += 3) {
		crc = crc8(scd4x_crc8_table, buf + i, 2, CRC8_INIT_VALUE);
		if (crc != buf[i + 2]) {
			dev_err(&client->dev, "CRC error\n");
			ret = -EIO;
			goto err;
		}

		*rsp++ = buf[i];
		*rsp++ = buf[i + 1];
	}

	return scd4x_send_command(state, CMD_START_MEAS);

err:
	/*
	 * on error try to start the measurement,
	 * puts sensor back into continuous measurement
	 */
	scd4x_send_command(state, CMD_START_MEAS);

	return ret;
}

static int scd4x_read_meas(struct scd4x_state *state, uint16_t *meas)
{
	int i, ret;
	__be16 buf[3];

	ret = scd4x_read(state, CMD_READ_MEAS, buf, sizeof(buf));
	if (ret)
		return ret;

	for (i = 0; i < ARRAY_SIZE(buf); i++)
		meas[i] = be16_to_cpu(buf[i]);

	return 0;
}

static int scd4x_wait_meas_poll(struct scd4x_state *state)
{
	struct i2c_client *client = state->client;
	int tries = 6;
	int ret;

	do {
		__be16 bval;
		uint16_t val;

		ret = scd4x_read(state, CMD_GET_DATA_READY, &bval, sizeof(bval));
		if (ret)
			return -EIO;
		val = be16_to_cpu(bval);

		/* new measurement available */
		if (val & 0x7FF)
			return 0;

		msleep_interruptible(1000);
	} while (--tries);

	/* try to start sensor on timeout */
	ret = scd4x_send_command(state, CMD_START_MEAS);
	if (ret)
		dev_err(&client->dev, "failed to start measurement: %d\n", ret);

	return -ETIMEDOUT;
}

static int scd4x_read_poll(struct scd4x_state *state, uint16_t *buf)
{
	int ret;

	ret = scd4x_wait_meas_poll(state);
	if (ret)
		return ret;

	return scd4x_read_meas(state, buf);
}

static int scd4x_read_channel(struct scd4x_state *state, int chan)
{
	int ret;
	uint16_t buf[3];

	ret = scd4x_read_poll(state, buf);
	if (ret)
		return ret;

	return buf[chan];
}

static int scd4x_read_raw(struct iio_dev *indio_dev,
			struct iio_chan_spec const *chan, int *val,
			int *val2, long mask)
{
	struct scd4x_state *state = iio_priv(indio_dev);
	int ret;
	__be16 tmp;

	switch (mask) {
	case IIO_CHAN_INFO_RAW:
		ret = iio_device_claim_direct_mode(indio_dev);
		if (ret)
			return ret;

		mutex_lock(&state->lock);
		ret = scd4x_read_channel(state, chan->address);
		mutex_unlock(&state->lock);

		iio_device_release_direct_mode(indio_dev);
		if (ret < 0)
			return ret;

		*val = ret;
		return IIO_VAL_INT;
	case IIO_CHAN_INFO_SCALE:
		if (chan->type == IIO_CONCENTRATION) {
			*val = 0;
			*val2 = 100;
			return IIO_VAL_INT_PLUS_MICRO;
		} else if (chan->type == IIO_TEMP) {
			*val = 175000;
			*val2 = 65536;
			return IIO_VAL_FRACTIONAL;
		} else if (chan->type == IIO_HUMIDITYRELATIVE) {
			*val = 100000;
			*val2 = 65536;
			return IIO_VAL_FRACTIONAL;
		}
		return -EINVAL;
	case IIO_CHAN_INFO_OFFSET:
		*val = -16852;
		*val2 = 114286;
		return IIO_VAL_INT_PLUS_MICRO;
	case IIO_CHAN_INFO_CALIBBIAS:
		mutex_lock(&state->lock);
		ret = scd4x_read(state, CMD_GET_TEMP_OFFSET, &tmp, sizeof(tmp));
		mutex_unlock(&state->lock);
		if (ret)
			return ret;

		*val = be16_to_cpu(tmp);

		return IIO_VAL_INT;
	default:
		return -EINVAL;
	}
}

static int scd4x_write_raw(struct iio_dev *indio_dev, struct iio_chan_spec const *chan,
				int val, int val2, long mask)
{
	struct scd4x_state *state = iio_priv(indio_dev);
	int ret = 0;

	switch (mask) {
	case IIO_CHAN_INFO_CALIBBIAS:
		mutex_lock(&state->lock);
		ret = scd4x_write(state, CMD_SET_TEMP_OFFSET, val);
		mutex_unlock(&state->lock);

		return ret;
	default:
		return -EINVAL;
	}
}

static ssize_t calibration_auto_enable_show(struct device *dev,
			struct device_attribute *attr, char *buf)
{
	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
	struct scd4x_state *state = iio_priv(indio_dev);
	int ret;
	__be16 bval;
	u16 val;

	mutex_lock(&state->lock);
	ret = scd4x_read(state, CMD_GET_ASC, &bval, sizeof(bval));
	mutex_unlock(&state->lock);
	if (ret) {
		dev_err(dev, "failed to read automatic calibration");
		return ret;
	}

	val = (be16_to_cpu(bval) & SCD4X_READY_MASK) ? 1 : 0;

	return sysfs_emit(buf, "%d\n", val);
}

static ssize_t calibration_auto_enable_store(struct device *dev,
					struct device_attribute *attr,
					const char *buf, size_t len)
{
	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
	struct scd4x_state *state = iio_priv(indio_dev);
	bool val;
	int ret;
	uint16_t value;

	ret = kstrtobool(buf, &val);
	if (ret)
		return ret;

	value = val;

	mutex_lock(&state->lock);
	ret = scd4x_write(state, CMD_SET_ASC, value);
	mutex_unlock(&state->lock);
	if (ret)
		dev_err(dev, "failed to set automatic calibration");

	return ret ?: len;
}

static ssize_t calibration_forced_value_store(struct device *dev,
					struct device_attribute *attr,
					const char *buf, size_t len)
{
	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
	struct scd4x_state *state = iio_priv(indio_dev);
	uint16_t val, arg;
	int ret;

	ret = kstrtou16(buf, 0, &arg);
	if (ret)
		return ret;

	if (arg < SCD4X_FRC_MIN_PPM || arg > SCD4X_FRC_MAX_PPM)
		return -EINVAL;

	mutex_lock(&state->lock);
	ret = scd4x_write_and_fetch(state, CMD_FRC, arg, &val, sizeof(val));
	mutex_unlock(&state->lock);

	if (ret)
		return ret;

	if (val == 0xff) {
		dev_err(dev, "forced calibration has failed");
		return -EINVAL;
	}

	return len;
}

static IIO_DEVICE_ATTR_RW(calibration_auto_enable, 0);
static IIO_DEVICE_ATTR_WO(calibration_forced_value, 0);

static IIO_CONST_ATTR(calibration_forced_value_available,
	       __stringify([SCD4X_FRC_MIN_PPM 1 SCD4X_FRC_MAX_PPM]));

static struct attribute *scd4x_attrs[] = {
	&iio_dev_attr_calibration_auto_enable.dev_attr.attr,
	&iio_dev_attr_calibration_forced_value.dev_attr.attr,
	&iio_const_attr_calibration_forced_value_available.dev_attr.attr,
	NULL
};

static const struct attribute_group scd4x_attr_group = {
	.attrs = scd4x_attrs,
};

static const struct iio_info scd4x_info = {
	.attrs = &scd4x_attr_group,
	.read_raw = scd4x_read_raw,
	.write_raw = scd4x_write_raw,
};

static const struct iio_chan_spec scd4x_channels[] = {
	{
		.type = IIO_CONCENTRATION,
		.channel2 = IIO_MOD_CO2,
		.modified = 1,
		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
					BIT(IIO_CHAN_INFO_SCALE),
		.address = SCD4X_CO2,
		.scan_index = SCD4X_CO2,
		.scan_type = {
			.sign = 'u',
			.realbits = 16,
			.storagebits = 16,
			.endianness = IIO_BE,
		},
	},
	{
		.type = IIO_TEMP,
		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
					BIT(IIO_CHAN_INFO_SCALE) |
					BIT(IIO_CHAN_INFO_OFFSET) |
					BIT(IIO_CHAN_INFO_CALIBBIAS),
		.address = SCD4X_TEMP,
		.scan_index = SCD4X_TEMP,
		.scan_type = {
			.sign = 'u',
			.realbits = 16,
			.storagebits = 16,
			.endianness = IIO_BE,
		},
	},
	{
		.type = IIO_HUMIDITYRELATIVE,
		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
					BIT(IIO_CHAN_INFO_SCALE),
		.address = SCD4X_HR,
		.scan_index = SCD4X_HR,
		.scan_type = {
			.sign = 'u',
			.realbits = 16,
			.storagebits = 16,
			.endianness = IIO_BE,
		},
	},
};

static int __maybe_unused scd4x_suspend(struct device *dev)
{
	struct iio_dev *indio_dev = dev_get_drvdata(dev);
	struct scd4x_state *state  = iio_priv(indio_dev);
	int ret;

	ret = scd4x_send_command(state, CMD_STOP_MEAS);
	if (ret)
		return ret;

	return regulator_disable(state->vdd);
}

static int __maybe_unused scd4x_resume(struct device *dev)
{
	struct iio_dev *indio_dev = dev_get_drvdata(dev);
	struct scd4x_state *state = iio_priv(indio_dev);
	int ret;

	ret = regulator_enable(state->vdd);
	if (ret)
		return ret;

	return scd4x_send_command(state, CMD_START_MEAS);
}

static __maybe_unused SIMPLE_DEV_PM_OPS(scd4x_pm_ops, scd4x_suspend, scd4x_resume);

static void scd4x_stop_meas(void *state)
{
	scd4x_send_command(state, CMD_STOP_MEAS);
}

static void scd4x_disable_regulator(void *data)
{
	struct scd4x_state *state = data;

	regulator_disable(state->vdd);
}

static irqreturn_t scd4x_trigger_handler(int irq, void *p)
{
	struct iio_poll_func *pf = p;
	struct iio_dev *indio_dev = pf->indio_dev;
	struct scd4x_state *state = iio_priv(indio_dev);
	struct {
		uint16_t data[3];
		int64_t ts __aligned(8);
	} scan;
	int ret;

	memset(&scan, 0, sizeof(scan));
	mutex_lock(&state->lock);
	ret = scd4x_read_poll(state, scan.data);
	mutex_unlock(&state->lock);
	if (ret)
		goto out;

	iio_push_to_buffers_with_timestamp(indio_dev, &scan, iio_get_time_ns(indio_dev));
out:
	iio_trigger_notify_done(indio_dev->trig);
	return IRQ_HANDLED;
}

static int scd4x_probe(struct i2c_client *client, const struct i2c_device_id *id)
{
	static const unsigned long scd4x_scan_masks[] = { 0x07, 0x00 };
	struct device *dev = &client->dev;
	struct iio_dev *indio_dev;
	struct scd4x_state *state;
	int ret;

	indio_dev = devm_iio_device_alloc(dev, sizeof(*state));
	if (!indio_dev)
		return -ENOMEM;

	state = iio_priv(indio_dev);
	mutex_init(&state->lock);
	state->client = client;
	crc8_populate_msb(scd4x_crc8_table, SCD4X_CRC8_POLYNOMIAL);

	indio_dev->info = &scd4x_info;
	indio_dev->name = client->name;
	indio_dev->channels = scd4x_channels;
	indio_dev->num_channels = ARRAY_SIZE(scd4x_channels);
	indio_dev->modes = INDIO_DIRECT_MODE;
	indio_dev->available_scan_masks = scd4x_scan_masks;

	state->vdd = devm_regulator_get(dev, "vdd");
	if (IS_ERR(state->vdd))
		return dev_err_probe(dev, PTR_ERR(state->vdd), "failed to get regulator\n");

	ret = regulator_enable(state->vdd);
	if (ret)
		return ret;

	ret = devm_add_action_or_reset(dev, scd4x_disable_regulator, state);
	if (ret)
		return ret;

	ret = scd4x_send_command(state, CMD_STOP_MEAS);
	if (ret) {
		dev_err(dev, "failed to stop measurement: %d\n", ret);
		return ret;
	}

	/* execution time */
	msleep_interruptible(500);

	ret = devm_iio_triggered_buffer_setup(dev, indio_dev, NULL, scd4x_trigger_handler, NULL);
	if (ret)
		return ret;

	ret = scd4x_send_command(state, CMD_START_MEAS);
	if (ret) {
		dev_err(dev, "failed to start measurement: %d\n", ret);
		return ret;
	}

	ret = devm_add_action_or_reset(dev, scd4x_stop_meas, state);
	if (ret)
		return ret;

	return devm_iio_device_register(dev, indio_dev);
}

static const struct of_device_id scd4x_dt_ids[] = {
	{ .compatible = "sensirion,scd40" },
	{ .compatible = "sensirion,scd41" },
	{ }
};
MODULE_DEVICE_TABLE(of, scd4x_dt_ids);

static struct i2c_driver scd4x_i2c_driver = {
	.driver = {
		.name = KBUILD_MODNAME,
		.of_match_table = scd4x_dt_ids,
		.pm = &scd4x_pm_ops
	},
	.probe = scd4x_probe,
};
module_i2c_driver(scd4x_i2c_driver);

MODULE_AUTHOR("Roan van Dijk <roan@protonic.nl>");
MODULE_DESCRIPTION("Sensirion SCD4X carbon dioxide sensor core driver");
MODULE_LICENSE("GPL v2");