scd30_core.c

  1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * Sensirion SCD30 carbon dioxide sensor core driver
  4 *
  5 * Copyright (c) 2020 Tomasz Duszynski <tomasz.duszynski@octakon.com>
  6 */
  7#include <linux/bits.h>
  8#include <linux/cleanup.h>
  9#include <linux/completion.h>
 10#include <linux/delay.h>
 11#include <linux/device.h>
 12#include <linux/errno.h>
 13#include <linux/export.h>
 14#include <linux/iio/buffer.h>
 15#include <linux/iio/iio.h>
 16#include <linux/iio/sysfs.h>
 17#include <linux/iio/trigger.h>
 18#include <linux/iio/trigger_consumer.h>
 19#include <linux/iio/triggered_buffer.h>
 20#include <linux/iio/types.h>
 21#include <linux/interrupt.h>
 22#include <linux/irqreturn.h>
 23#include <linux/jiffies.h>
 24#include <linux/kernel.h>
 25#include <linux/module.h>
 26#include <linux/mutex.h>
 27#include <linux/regulator/consumer.h>
 28#include <linux/string.h>
 29#include <linux/sysfs.h>
 30#include <linux/types.h>
 31#include <asm/byteorder.h>
 32
 33#include "scd30.h"
 34
 35#define SCD30_PRESSURE_COMP_MIN_MBAR 700
 36#define SCD30_PRESSURE_COMP_MAX_MBAR 1400
 37#define SCD30_PRESSURE_COMP_DEFAULT 1013
 38#define SCD30_MEAS_INTERVAL_MIN_S 2
 39#define SCD30_MEAS_INTERVAL_MAX_S 1800
 40#define SCD30_MEAS_INTERVAL_DEFAULT SCD30_MEAS_INTERVAL_MIN_S
 41#define SCD30_FRC_MIN_PPM 400
 42#define SCD30_FRC_MAX_PPM 2000
 43#define SCD30_TEMP_OFFSET_MAX 655360
 44#define SCD30_EXTRA_TIMEOUT_PER_S 250
 45
 46enum {
 47	SCD30_CONC,
 48	SCD30_TEMP,
 49	SCD30_HR,
 50};
 51
 52static int scd30_command_write(struct scd30_state *state, enum scd30_cmd cmd, u16 arg)
 53{
 54	return state->command(state, cmd, arg, NULL, 0);
 55}
 56
 57static int scd30_command_read(struct scd30_state *state, enum scd30_cmd cmd, u16 *val)
 58{
 59	__be16 tmp;
 60	int ret;
 61
 62	ret = state->command(state, cmd, 0, &tmp, sizeof(tmp));
 63	*val = be16_to_cpup(&tmp);
 64
 65	return ret;
 66}
 67
 68static int scd30_reset(struct scd30_state *state)
 69{
 70	int ret;
 71	u16 val;
 72
 73	ret = scd30_command_write(state, CMD_RESET, 0);
 74	if (ret)
 75		return ret;
 76
 77	/* sensor boots up within 2 secs */
 78	msleep(2000);
 79	/*
 80	 * Power-on-reset causes sensor to produce some glitch on i2c bus and
 81	 * some controllers end up in error state. Try to recover by placing
 82	 * any data on the bus.
 83	 */
 84	scd30_command_read(state, CMD_MEAS_READY, &val);
 85
 86	return 0;
 87}
 88
 89/* simplified float to fixed point conversion with a scaling factor of 0.01 */
 90static int scd30_float_to_fp(int float32)
 91{
 92	int fraction, shift,
 93	    mantissa = float32 & GENMASK(22, 0),
 94	    sign = (float32 & BIT(31)) ? -1 : 1,
 95	    exp = (float32 & ~BIT(31)) >> 23;
 96
 97	/* special case 0 */
 98	if (!exp && !mantissa)
 99		return 0;
100
101	exp -= 127;
102	if (exp < 0) {
103		exp = -exp;
104		/* return values ranging from 1 to 99 */
105		return sign * ((((BIT(23) + mantissa) * 100) >> 23) >> exp);
106	}
107
108	/* return values starting at 100 */
109	shift = 23 - exp;
110	float32 = BIT(exp) + (mantissa >> shift);
111	fraction = mantissa & GENMASK(shift - 1, 0);
112
113	return sign * (float32 * 100 + ((fraction * 100) >> shift));
114}
115
116static int scd30_read_meas(struct scd30_state *state)
117{
118	int i, ret;
119
120	ret = state->command(state, CMD_READ_MEAS, 0, state->meas, sizeof(state->meas));
121	if (ret)
122		return ret;
123
124	be32_to_cpu_array(state->meas, (__be32 *)state->meas, ARRAY_SIZE(state->meas));
125
126	for (i = 0; i < ARRAY_SIZE(state->meas); i++)
127		state->meas[i] = scd30_float_to_fp(state->meas[i]);
128
129	/*
130	 * co2 is left unprocessed while temperature and humidity are scaled
131	 * to milli deg C and milli percent respectively.
132	 */
133	state->meas[SCD30_TEMP] *= 10;
134	state->meas[SCD30_HR] *= 10;
135
136	return 0;
137}
138
139static int scd30_wait_meas_irq(struct scd30_state *state)
140{
141	int ret, timeout;
142
143	reinit_completion(&state->meas_ready);
144	enable_irq(state->irq);
145	timeout = msecs_to_jiffies(state->meas_interval * (1000 + SCD30_EXTRA_TIMEOUT_PER_S));
146	ret = wait_for_completion_interruptible_timeout(&state->meas_ready, timeout);
147	if (ret > 0)
148		ret = 0;
149	else if (!ret)
150		ret = -ETIMEDOUT;
151
152	disable_irq(state->irq);
153
154	return ret;
155}
156
157static int scd30_wait_meas_poll(struct scd30_state *state)
158{
159	int timeout = state->meas_interval * SCD30_EXTRA_TIMEOUT_PER_S, tries = 5;
160
161	do {
162		int ret;
163		u16 val;
164
165		ret = scd30_command_read(state, CMD_MEAS_READY, &val);
166		if (ret)
167			return -EIO;
168
169		/* new measurement available */
170		if (val)
171			break;
172
173		msleep_interruptible(timeout);
174	} while (--tries);
175
176	return tries ? 0 : -ETIMEDOUT;
177}
178
179static int scd30_read_poll(struct scd30_state *state)
180{
181	int ret;
182
183	ret = scd30_wait_meas_poll(state);
184	if (ret)
185		return ret;
186
187	return scd30_read_meas(state);
188}
189
190static int scd30_read(struct scd30_state *state)
191{
192	if (state->irq > 0)
193		return scd30_wait_meas_irq(state);
194
195	return scd30_read_poll(state);
196}
197
198static int scd30_read_raw(struct iio_dev *indio_dev, struct iio_chan_spec const *chan,
199			  int *val, int *val2, long mask)
200{
201	struct scd30_state *state = iio_priv(indio_dev);
202	int ret;
203	u16 tmp;
204
205	guard(mutex)(&state->lock);
206	switch (mask) {
207	case IIO_CHAN_INFO_RAW:
208	case IIO_CHAN_INFO_PROCESSED:
209		if (chan->output) {
210			*val = state->pressure_comp;
211			return IIO_VAL_INT;
212		}
213
214		if (!iio_device_claim_direct(indio_dev))
215			return -EBUSY;
216
217		ret = scd30_read(state);
218		if (ret) {
219			iio_device_release_direct(indio_dev);
220			return ret;
221		}
222
223		*val = state->meas[chan->address];
224		iio_device_release_direct(indio_dev);
225		return IIO_VAL_INT;
226	case IIO_CHAN_INFO_SCALE:
227		*val = 0;
228		*val2 = 1;
229		return IIO_VAL_INT_PLUS_MICRO;
230	case IIO_CHAN_INFO_SAMP_FREQ:
231		ret = scd30_command_read(state, CMD_MEAS_INTERVAL, &tmp);
232		if (ret)
233			return ret;
234
235		*val = 0;
236		*val2 = 1000000000 / tmp;
237		return IIO_VAL_INT_PLUS_NANO;
238	case IIO_CHAN_INFO_CALIBBIAS:
239		ret = scd30_command_read(state, CMD_TEMP_OFFSET, &tmp);
240		if (ret)
241			return ret;
242
243		*val = tmp;
244		return IIO_VAL_INT;
245	default:
246		return -EINVAL;
247	}
248}
249
250static int scd30_write_raw(struct iio_dev *indio_dev, struct iio_chan_spec const *chan,
251			   int val, int val2, long mask)
252{
253	struct scd30_state *state = iio_priv(indio_dev);
254	int ret;
255
256	guard(mutex)(&state->lock);
257	switch (mask) {
258	case IIO_CHAN_INFO_SAMP_FREQ:
259		if (val)
260			return -EINVAL;
261
262		val = 1000000000 / val2;
263		if (val < SCD30_MEAS_INTERVAL_MIN_S || val > SCD30_MEAS_INTERVAL_MAX_S)
264			return -EINVAL;
265
266		ret = scd30_command_write(state, CMD_MEAS_INTERVAL, val);
267		if (ret)
268			return ret;
269
270		state->meas_interval = val;
271		return 0;
272	case IIO_CHAN_INFO_RAW:
273		switch (chan->type) {
274		case IIO_PRESSURE:
275			if (val < SCD30_PRESSURE_COMP_MIN_MBAR ||
276			    val > SCD30_PRESSURE_COMP_MAX_MBAR)
277				return -EINVAL;
278
279			ret = scd30_command_write(state, CMD_START_MEAS, val);
280			if (ret)
281				return ret;
282
283			state->pressure_comp = val;
284			return 0;
285		default:
286			return -EINVAL;
287		}
288	case IIO_CHAN_INFO_CALIBBIAS:
289		if (val < 0 || val > SCD30_TEMP_OFFSET_MAX)
290			return -EINVAL;
291		/*
292		 * Manufacturer does not explicitly specify min/max sensible
293		 * values hence check is omitted for simplicity.
294		 */
295		return scd30_command_write(state, CMD_TEMP_OFFSET / 10, val);
296	default:
297		return -EINVAL;
298	}
299}
300
301static int scd30_write_raw_get_fmt(struct iio_dev *indio_dev, struct iio_chan_spec const *chan,
302				   long mask)
303{
304	switch (mask) {
305	case IIO_CHAN_INFO_SAMP_FREQ:
306		return IIO_VAL_INT_PLUS_NANO;
307	case IIO_CHAN_INFO_RAW:
308	case IIO_CHAN_INFO_CALIBBIAS:
309		return IIO_VAL_INT;
310	}
311
312	return -EINVAL;
313}
314
315static const int scd30_pressure_raw_available[] = {
316	SCD30_PRESSURE_COMP_MIN_MBAR, 1, SCD30_PRESSURE_COMP_MAX_MBAR,
317};
318
319static const int scd30_temp_calibbias_available[] = {
320	0, 10, SCD30_TEMP_OFFSET_MAX,
321};
322
323static int scd30_read_avail(struct iio_dev *indio_dev, struct iio_chan_spec const *chan,
324			    const int **vals, int *type, int *length, long mask)
325{
326	switch (mask) {
327	case IIO_CHAN_INFO_RAW:
328		*vals = scd30_pressure_raw_available;
329		*type = IIO_VAL_INT;
330
331		return IIO_AVAIL_RANGE;
332	case IIO_CHAN_INFO_CALIBBIAS:
333		*vals = scd30_temp_calibbias_available;
334		*type = IIO_VAL_INT;
335
336		return IIO_AVAIL_RANGE;
337	}
338
339	return -EINVAL;
340}
341
342static ssize_t sampling_frequency_available_show(struct device *dev, struct device_attribute *attr,
343						 char *buf)
344{
345	int i = SCD30_MEAS_INTERVAL_MIN_S;
346	ssize_t len = 0;
347
348	do {
349		len += sysfs_emit_at(buf, len, "0.%09u ", 1000000000 / i);
350		/*
351		 * Not all values fit PAGE_SIZE buffer hence print every 6th
352		 * (each frequency differs by 6s in time domain from the
353		 * adjacent). Unlisted but valid ones are still accepted.
354		 */
355		i += 6;
356	} while (i <= SCD30_MEAS_INTERVAL_MAX_S);
357
358	buf[len - 1] = '\n';
359
360	return len;
361}
362
363static ssize_t calibration_auto_enable_show(struct device *dev, struct device_attribute *attr,
364					    char *buf)
365{
366	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
367	struct scd30_state *state = iio_priv(indio_dev);
368	int ret;
369	u16 val;
370
371	mutex_lock(&state->lock);
372	ret = scd30_command_read(state, CMD_ASC, &val);
373	mutex_unlock(&state->lock);
374
375	return ret ?: sysfs_emit(buf, "%d\n", val);
376}
377
378static ssize_t calibration_auto_enable_store(struct device *dev, struct device_attribute *attr,
379					     const char *buf, size_t len)
380{
381	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
382	struct scd30_state *state = iio_priv(indio_dev);
383	bool val;
384	int ret;
385
386	ret = kstrtobool(buf, &val);
387	if (ret)
388		return ret;
389
390	mutex_lock(&state->lock);
391	ret = scd30_command_write(state, CMD_ASC, val);
392	mutex_unlock(&state->lock);
393
394	return ret ?: len;
395}
396
397static ssize_t calibration_forced_value_show(struct device *dev, struct device_attribute *attr,
398					     char *buf)
399{
400	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
401	struct scd30_state *state = iio_priv(indio_dev);
402	int ret;
403	u16 val;
404
405	mutex_lock(&state->lock);
406	ret = scd30_command_read(state, CMD_FRC, &val);
407	mutex_unlock(&state->lock);
408
409	return ret ?: sysfs_emit(buf, "%d\n", val);
410}
411
412static ssize_t calibration_forced_value_store(struct device *dev, struct device_attribute *attr,
413					      const char *buf, size_t len)
414{
415	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
416	struct scd30_state *state = iio_priv(indio_dev);
417	int ret;
418	u16 val;
419
420	ret = kstrtou16(buf, 0, &val);
421	if (ret)
422		return ret;
423
424	if (val < SCD30_FRC_MIN_PPM || val > SCD30_FRC_MAX_PPM)
425		return -EINVAL;
426
427	mutex_lock(&state->lock);
428	ret = scd30_command_write(state, CMD_FRC, val);
429	mutex_unlock(&state->lock);
430
431	return ret ?: len;
432}
433
434static IIO_DEVICE_ATTR_RO(sampling_frequency_available, 0);
435static IIO_DEVICE_ATTR_RW(calibration_auto_enable, 0);
436static IIO_DEVICE_ATTR_RW(calibration_forced_value, 0);
437
438static struct attribute *scd30_attrs[] = {
439	&iio_dev_attr_sampling_frequency_available.dev_attr.attr,
440	&iio_dev_attr_calibration_auto_enable.dev_attr.attr,
441	&iio_dev_attr_calibration_forced_value.dev_attr.attr,
442	NULL
443};
444
445static const struct attribute_group scd30_attr_group = {
446	.attrs = scd30_attrs,
447};
448
449static const struct iio_info scd30_info = {
450	.attrs = &scd30_attr_group,
451	.read_raw = scd30_read_raw,
452	.write_raw = scd30_write_raw,
453	.write_raw_get_fmt = scd30_write_raw_get_fmt,
454	.read_avail = scd30_read_avail,
455};
456
457#define SCD30_CHAN_SCAN_TYPE(_sign, _realbits) .scan_type = { \
458	.sign = _sign, \
459	.realbits = _realbits, \
460	.storagebits = 32, \
461	.endianness = IIO_CPU, \
462}
463
464static const struct iio_chan_spec scd30_channels[] = {
465	{
466		/*
467		 * this channel is special in a sense we are pretending that
468		 * sensor is able to change measurement chamber pressure but in
469		 * fact we're just setting pressure compensation value
470		 */
471		.type = IIO_PRESSURE,
472		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
473		.info_mask_separate_available = BIT(IIO_CHAN_INFO_RAW),
474		.output = 1,
475		.scan_index = -1,
476	},
477	{
478		.type = IIO_CONCENTRATION,
479		.channel2 = IIO_MOD_CO2,
480		.address = SCD30_CONC,
481		.scan_index = SCD30_CONC,
482		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
483				      BIT(IIO_CHAN_INFO_SCALE),
484		.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ),
485		.modified = 1,
486
487		SCD30_CHAN_SCAN_TYPE('u', 20),
488	},
489	{
490		.type = IIO_TEMP,
491		.address = SCD30_TEMP,
492		.scan_index = SCD30_TEMP,
493		.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED) |
494				      BIT(IIO_CHAN_INFO_CALIBBIAS),
495		.info_mask_separate_available = BIT(IIO_CHAN_INFO_CALIBBIAS),
496		.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ),
497
498		SCD30_CHAN_SCAN_TYPE('s', 18),
499	},
500	{
501		.type = IIO_HUMIDITYRELATIVE,
502		.address = SCD30_HR,
503		.scan_index = SCD30_HR,
504		.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
505		.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ),
506
507		SCD30_CHAN_SCAN_TYPE('u', 17),
508	},
509	IIO_CHAN_SOFT_TIMESTAMP(3),
510};
511
512static int scd30_suspend(struct device *dev)
513{
514	struct iio_dev *indio_dev = dev_get_drvdata(dev);
515	struct scd30_state *state  = iio_priv(indio_dev);
516	int ret;
517
518	ret = scd30_command_write(state, CMD_STOP_MEAS, 0);
519	if (ret)
520		return ret;
521
522	return regulator_disable(state->vdd);
523}
524
525static int scd30_resume(struct device *dev)
526{
527	struct iio_dev *indio_dev = dev_get_drvdata(dev);
528	struct scd30_state *state = iio_priv(indio_dev);
529	int ret;
530
531	ret = regulator_enable(state->vdd);
532	if (ret)
533		return ret;
534
535	return scd30_command_write(state, CMD_START_MEAS, state->pressure_comp);
536}
537
538EXPORT_NS_SIMPLE_DEV_PM_OPS(scd30_pm_ops, scd30_suspend, scd30_resume, IIO_SCD30);
539
540static void scd30_stop_meas(void *data)
541{
542	struct scd30_state *state = data;
543
544	scd30_command_write(state, CMD_STOP_MEAS, 0);
545}
546
547static void scd30_disable_regulator(void *data)
548{
549	struct scd30_state *state = data;
550
551	regulator_disable(state->vdd);
552}
553
554static irqreturn_t scd30_irq_handler(int irq, void *priv)
555{
556	struct iio_dev *indio_dev = priv;
557
558	if (iio_buffer_enabled(indio_dev)) {
559		iio_trigger_poll(indio_dev->trig);
560
561		return IRQ_HANDLED;
562	}
563
564	return IRQ_WAKE_THREAD;
565}
566
567static irqreturn_t scd30_irq_thread_handler(int irq, void *priv)
568{
569	struct iio_dev *indio_dev = priv;
570	struct scd30_state *state = iio_priv(indio_dev);
571	int ret;
572
573	ret = scd30_read_meas(state);
574	if (ret)
575		goto out;
576
577	complete_all(&state->meas_ready);
578out:
579	return IRQ_HANDLED;
580}
581
582static irqreturn_t scd30_trigger_handler(int irq, void *p)
583{
584	struct iio_poll_func *pf = p;
585	struct iio_dev *indio_dev = pf->indio_dev;
586	struct scd30_state *state = iio_priv(indio_dev);
587	struct {
588		int data[SCD30_MEAS_COUNT];
589		aligned_s64 ts;
590	} scan = { };
591	int ret;
592
593	mutex_lock(&state->lock);
594	if (!iio_trigger_using_own(indio_dev))
595		ret = scd30_read_poll(state);
596	else
597		ret = scd30_read_meas(state);
598	memcpy(scan.data, state->meas, sizeof(state->meas));
599	mutex_unlock(&state->lock);
600	if (ret)
601		goto out;
602
603	iio_push_to_buffers_with_ts(indio_dev, &scan, sizeof(scan),
604				    iio_get_time_ns(indio_dev));
605out:
606	iio_trigger_notify_done(indio_dev->trig);
607	return IRQ_HANDLED;
608}
609
610static int scd30_set_trigger_state(struct iio_trigger *trig, bool state)
611{
612	struct iio_dev *indio_dev = iio_trigger_get_drvdata(trig);
613	struct scd30_state *st = iio_priv(indio_dev);
614
615	if (state)
616		enable_irq(st->irq);
617	else
618		disable_irq(st->irq);
619
620	return 0;
621}
622
623static const struct iio_trigger_ops scd30_trigger_ops = {
624	.set_trigger_state = scd30_set_trigger_state,
625	.validate_device = iio_trigger_validate_own_device,
626};
627
628static int scd30_setup_trigger(struct iio_dev *indio_dev)
629{
630	struct scd30_state *state = iio_priv(indio_dev);
631	struct device *dev = indio_dev->dev.parent;
632	struct iio_trigger *trig;
633	int ret;
634
635	trig = devm_iio_trigger_alloc(dev, "%s-dev%d", indio_dev->name,
636				      iio_device_id(indio_dev));
637	if (!trig)
638		return -ENOMEM;
639
640	trig->ops = &scd30_trigger_ops;
641	iio_trigger_set_drvdata(trig, indio_dev);
642
643	ret = devm_iio_trigger_register(dev, trig);
644	if (ret)
645		return ret;
646
647	indio_dev->trig = iio_trigger_get(trig);
648
649	/*
650	 * Interrupt is enabled just before taking a fresh measurement
651	 * and disabled afterwards. This means we need to ensure it is not
652	 * enabled here to keep calls to enable/disable balanced.
653	 */
654	ret = devm_request_threaded_irq(dev, state->irq, scd30_irq_handler,
655					scd30_irq_thread_handler,
656					IRQF_TRIGGER_HIGH | IRQF_ONESHOT |
657					IRQF_NO_AUTOEN,
658					indio_dev->name, indio_dev);
659	if (ret)
660		return dev_err_probe(dev, ret, "failed to request irq\n");
661
662	return 0;
663}
664
665int scd30_probe(struct device *dev, int irq, const char *name, void *priv,
666		scd30_command_t command)
667{
668	static const unsigned long scd30_scan_masks[] = { 0x07, 0x00 };
669	struct scd30_state *state;
670	struct iio_dev *indio_dev;
671	int ret;
672	u16 val;
673
674	indio_dev = devm_iio_device_alloc(dev, sizeof(*state));
675	if (!indio_dev)
676		return -ENOMEM;
677
678	state = iio_priv(indio_dev);
679	state->dev = dev;
680	state->priv = priv;
681	state->irq = irq;
682	state->pressure_comp = SCD30_PRESSURE_COMP_DEFAULT;
683	state->meas_interval = SCD30_MEAS_INTERVAL_DEFAULT;
684	state->command = command;
685	mutex_init(&state->lock);
686	init_completion(&state->meas_ready);
687
688	dev_set_drvdata(dev, indio_dev);
689
690	indio_dev->info = &scd30_info;
691	indio_dev->name = name;
692	indio_dev->channels = scd30_channels;
693	indio_dev->num_channels = ARRAY_SIZE(scd30_channels);
694	indio_dev->modes = INDIO_DIRECT_MODE;
695	indio_dev->available_scan_masks = scd30_scan_masks;
696
697	state->vdd = devm_regulator_get(dev, "vdd");
698	if (IS_ERR(state->vdd))
699		return dev_err_probe(dev, PTR_ERR(state->vdd), "failed to get regulator\n");
700
701	ret = regulator_enable(state->vdd);
702	if (ret)
703		return ret;
704
705	ret = devm_add_action_or_reset(dev, scd30_disable_regulator, state);
706	if (ret)
707		return ret;
708
709	ret = scd30_reset(state);
710	if (ret)
711		return dev_err_probe(dev, ret, "failed to reset device\n");
712
713	if (state->irq > 0) {
714		ret = scd30_setup_trigger(indio_dev);
715		if (ret)
716			return dev_err_probe(dev, ret, "failed to setup trigger\n");
717	}
718
719	ret = devm_iio_triggered_buffer_setup(dev, indio_dev, NULL, scd30_trigger_handler, NULL);
720	if (ret)
721		return ret;
722
723	ret = scd30_command_read(state, CMD_FW_VERSION, &val);
724	if (ret)
725		return dev_err_probe(dev, ret, "failed to read firmware version\n");
726	dev_info(dev, "firmware version: %d.%d\n", val >> 8, (char)val);
727
728	ret = scd30_command_write(state, CMD_MEAS_INTERVAL, state->meas_interval);
729	if (ret)
730		return dev_err_probe(dev, ret, "failed to set measurement interval\n");
731
732	ret = scd30_command_write(state, CMD_START_MEAS, state->pressure_comp);
733	if (ret)
734		return dev_err_probe(dev, ret, "failed to start measurement\n");
735
736	ret = devm_add_action_or_reset(dev, scd30_stop_meas, state);
737	if (ret)
738		return ret;
739
740	return devm_iio_device_register(dev, indio_dev);
741}
742EXPORT_SYMBOL_NS(scd30_probe, "IIO_SCD30");
743
744MODULE_AUTHOR("Tomasz Duszynski <tomasz.duszynski@octakon.com>");
745MODULE_DESCRIPTION("Sensirion SCD30 carbon dioxide sensor core driver");
746MODULE_LICENSE("GPL v2");