summaryrefslogtreecommitdiff
path: root/drivers/iio/humidity/hts221_core.c
blob: 32524a8dc66f6555ee155792284377f03b57d8b1 (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
/*
 * STMicroelectronics hts221 sensor driver
 *
 * Copyright 2016 STMicroelectronics Inc.
 *
 * Lorenzo Bianconi <lorenzo.bianconi@st.com>
 *
 * Licensed under the GPL-2.
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/device.h>
#include <linux/iio/sysfs.h>
#include <linux/delay.h>
#include <linux/pm.h>
#include <asm/unaligned.h>

#include "hts221.h"

#define HTS221_REG_WHOAMI_ADDR		0x0f
#define HTS221_REG_WHOAMI_VAL		0xbc

#define HTS221_REG_CNTRL1_ADDR		0x20
#define HTS221_REG_CNTRL2_ADDR		0x21

#define HTS221_REG_AVG_ADDR		0x10
#define HTS221_REG_H_OUT_L		0x28
#define HTS221_REG_T_OUT_L		0x2a

#define HTS221_HUMIDITY_AVG_MASK	0x07
#define HTS221_TEMP_AVG_MASK		0x38

#define HTS221_ODR_MASK			0x03
#define HTS221_BDU_MASK			BIT(2)
#define HTS221_ENABLE_MASK		BIT(7)

/* calibration registers */
#define HTS221_REG_0RH_CAL_X_H		0x36
#define HTS221_REG_1RH_CAL_X_H		0x3a
#define HTS221_REG_0RH_CAL_Y_H		0x30
#define HTS221_REG_1RH_CAL_Y_H		0x31
#define HTS221_REG_0T_CAL_X_L		0x3c
#define HTS221_REG_1T_CAL_X_L		0x3e
#define HTS221_REG_0T_CAL_Y_H		0x32
#define HTS221_REG_1T_CAL_Y_H		0x33
#define HTS221_REG_T1_T0_CAL_Y_H	0x35

struct hts221_odr {
	u8 hz;
	u8 val;
};

#define HTS221_AVG_DEPTH		8
struct hts221_avg {
	u8 addr;
	u8 mask;
	u16 avg_avl[HTS221_AVG_DEPTH];
};

static const struct hts221_odr hts221_odr_table[] = {
	{  1, 0x01 },	/* 1Hz */
	{  7, 0x02 },	/* 7Hz */
	{ 13, 0x03 },	/* 12.5Hz */
};

static const struct hts221_avg hts221_avg_list[] = {
	{
		.addr = HTS221_REG_AVG_ADDR,
		.mask = HTS221_HUMIDITY_AVG_MASK,
		.avg_avl = {
			4, /* 0.4 %RH */
			8, /* 0.3 %RH */
			16, /* 0.2 %RH */
			32, /* 0.15 %RH */
			64, /* 0.1 %RH */
			128, /* 0.07 %RH */
			256, /* 0.05 %RH */
			512, /* 0.03 %RH */
		},
	},
	{
		.addr = HTS221_REG_AVG_ADDR,
		.mask = HTS221_TEMP_AVG_MASK,
		.avg_avl = {
			2, /* 0.08 degC */
			4, /* 0.05 degC */
			8, /* 0.04 degC */
			16, /* 0.03 degC */
			32, /* 0.02 degC */
			64, /* 0.015 degC */
			128, /* 0.01 degC */
			256, /* 0.007 degC */
		},
	},
};

static const struct iio_chan_spec hts221_channels[] = {
	{
		.type = IIO_HUMIDITYRELATIVE,
		.address = HTS221_REG_H_OUT_L,
		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
				      BIT(IIO_CHAN_INFO_OFFSET) |
				      BIT(IIO_CHAN_INFO_SCALE) |
				      BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),
		.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ),
		.scan_index = 0,
		.scan_type = {
			.sign = 's',
			.realbits = 16,
			.storagebits = 16,
			.endianness = IIO_LE,
		},
	},
	{
		.type = IIO_TEMP,
		.address = HTS221_REG_T_OUT_L,
		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
				      BIT(IIO_CHAN_INFO_OFFSET) |
				      BIT(IIO_CHAN_INFO_SCALE) |
				      BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),
		.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ),
		.scan_index = 1,
		.scan_type = {
			.sign = 's',
			.realbits = 16,
			.storagebits = 16,
			.endianness = IIO_LE,
		},
	},
	IIO_CHAN_SOFT_TIMESTAMP(2),
};

int hts221_write_with_mask(struct hts221_hw *hw, u8 addr, u8 mask, u8 val)
{
	u8 data;
	int err;

	mutex_lock(&hw->lock);

	err = hw->tf->read(hw->dev, addr, sizeof(data), &data);
	if (err < 0) {
		dev_err(hw->dev, "failed to read %02x register\n", addr);
		goto unlock;
	}

	data = (data & ~mask) | ((val << __ffs(mask)) & mask);

	err = hw->tf->write(hw->dev, addr, sizeof(data), &data);
	if (err < 0)
		dev_err(hw->dev, "failed to write %02x register\n", addr);

unlock:
	mutex_unlock(&hw->lock);

	return err;
}

static int hts221_check_whoami(struct hts221_hw *hw)
{
	u8 data;
	int err;

	err = hw->tf->read(hw->dev, HTS221_REG_WHOAMI_ADDR, sizeof(data),
			   &data);
	if (err < 0) {
		dev_err(hw->dev, "failed to read whoami register\n");
		return err;
	}

	if (data != HTS221_REG_WHOAMI_VAL) {
		dev_err(hw->dev, "wrong whoami {%02x vs %02x}\n",
			data, HTS221_REG_WHOAMI_VAL);
		return -ENODEV;
	}

	return 0;
}

static int hts221_update_odr(struct hts221_hw *hw, u8 odr)
{
	int i, err;

	for (i = 0; i < ARRAY_SIZE(hts221_odr_table); i++)
		if (hts221_odr_table[i].hz == odr)
			break;

	if (i == ARRAY_SIZE(hts221_odr_table))
		return -EINVAL;

	err = hts221_write_with_mask(hw, HTS221_REG_CNTRL1_ADDR,
				     HTS221_ODR_MASK, hts221_odr_table[i].val);
	if (err < 0)
		return err;

	hw->odr = odr;

	return 0;
}

static int hts221_update_avg(struct hts221_hw *hw,
			     enum hts221_sensor_type type,
			     u16 val)
{
	int i, err;
	const struct hts221_avg *avg = &hts221_avg_list[type];

	for (i = 0; i < HTS221_AVG_DEPTH; i++)
		if (avg->avg_avl[i] == val)
			break;

	if (i == HTS221_AVG_DEPTH)
		return -EINVAL;

	err = hts221_write_with_mask(hw, avg->addr, avg->mask, i);
	if (err < 0)
		return err;

	hw->sensors[type].cur_avg_idx = i;

	return 0;
}

static ssize_t hts221_sysfs_sampling_freq(struct device *dev,
					  struct device_attribute *attr,
					  char *buf)
{
	int i;
	ssize_t len = 0;

	for (i = 0; i < ARRAY_SIZE(hts221_odr_table); i++)
		len += scnprintf(buf + len, PAGE_SIZE - len, "%d ",
				 hts221_odr_table[i].hz);
	buf[len - 1] = '\n';

	return len;
}

static ssize_t
hts221_sysfs_rh_oversampling_avail(struct device *dev,
				   struct device_attribute *attr,
				   char *buf)
{
	const struct hts221_avg *avg = &hts221_avg_list[HTS221_SENSOR_H];
	ssize_t len = 0;
	int i;

	for (i = 0; i < ARRAY_SIZE(avg->avg_avl); i++)
		len += scnprintf(buf + len, PAGE_SIZE - len, "%d ",
				 avg->avg_avl[i]);
	buf[len - 1] = '\n';

	return len;
}

static ssize_t
hts221_sysfs_temp_oversampling_avail(struct device *dev,
				     struct device_attribute *attr,
				     char *buf)
{
	const struct hts221_avg *avg = &hts221_avg_list[HTS221_SENSOR_T];
	ssize_t len = 0;
	int i;

	for (i = 0; i < ARRAY_SIZE(avg->avg_avl); i++)
		len += scnprintf(buf + len, PAGE_SIZE - len, "%d ",
				 avg->avg_avl[i]);
	buf[len - 1] = '\n';

	return len;
}

int hts221_set_enable(struct hts221_hw *hw, bool enable)
{
	int err;

	err = hts221_write_with_mask(hw, HTS221_REG_CNTRL1_ADDR,
				     HTS221_ENABLE_MASK, enable);
	if (err < 0)
		return err;

	hw->enabled = enable;

	return 0;
}

static int hts221_parse_temp_caldata(struct hts221_hw *hw)
{
	int err, *slope, *b_gen;
	s16 cal_x0, cal_x1, cal_y0, cal_y1;
	u8 cal0, cal1;

	err = hw->tf->read(hw->dev, HTS221_REG_0T_CAL_Y_H,
			   sizeof(cal0), &cal0);
	if (err < 0)
		return err;

	err = hw->tf->read(hw->dev, HTS221_REG_T1_T0_CAL_Y_H,
			   sizeof(cal1), &cal1);
	if (err < 0)
		return err;
	cal_y0 = (le16_to_cpu(cal1 & 0x3) << 8) | cal0;

	err = hw->tf->read(hw->dev, HTS221_REG_1T_CAL_Y_H,
			   sizeof(cal0), &cal0);
	if (err < 0)
		return err;
	cal_y1 = (((cal1 & 0xc) >> 2) << 8) | cal0;

	err = hw->tf->read(hw->dev, HTS221_REG_0T_CAL_X_L, sizeof(cal_x0),
			   (u8 *)&cal_x0);
	if (err < 0)
		return err;
	cal_x0 = le16_to_cpu(cal_x0);

	err = hw->tf->read(hw->dev, HTS221_REG_1T_CAL_X_L, sizeof(cal_x1),
			   (u8 *)&cal_x1);
	if (err < 0)
		return err;
	cal_x1 = le16_to_cpu(cal_x1);

	slope = &hw->sensors[HTS221_SENSOR_T].slope;
	b_gen = &hw->sensors[HTS221_SENSOR_T].b_gen;

	*slope = ((cal_y1 - cal_y0) * 8000) / (cal_x1 - cal_x0);
	*b_gen = (((s32)cal_x1 * cal_y0 - (s32)cal_x0 * cal_y1) * 1000) /
		 (cal_x1 - cal_x0);
	*b_gen *= 8;

	return 0;
}

static int hts221_parse_rh_caldata(struct hts221_hw *hw)
{
	int err, *slope, *b_gen;
	s16 cal_x0, cal_x1, cal_y0, cal_y1;
	u8 data;

	err = hw->tf->read(hw->dev, HTS221_REG_0RH_CAL_Y_H, sizeof(data),
			   &data);
	if (err < 0)
		return err;
	cal_y0 = data;

	err = hw->tf->read(hw->dev, HTS221_REG_1RH_CAL_Y_H, sizeof(data),
			   &data);
	if (err < 0)
		return err;
	cal_y1 = data;

	err = hw->tf->read(hw->dev, HTS221_REG_0RH_CAL_X_H, sizeof(cal_x0),
			   (u8 *)&cal_x0);
	if (err < 0)
		return err;
	cal_x0 = le16_to_cpu(cal_x0);

	err = hw->tf->read(hw->dev, HTS221_REG_1RH_CAL_X_H, sizeof(cal_x1),
			   (u8 *)&cal_x1);
	if (err < 0)
		return err;
	cal_x1 = le16_to_cpu(cal_x1);

	slope = &hw->sensors[HTS221_SENSOR_H].slope;
	b_gen = &hw->sensors[HTS221_SENSOR_H].b_gen;

	*slope = ((cal_y1 - cal_y0) * 8000) / (cal_x1 - cal_x0);
	*b_gen = (((s32)cal_x1 * cal_y0 - (s32)cal_x0 * cal_y1) * 1000) /
		 (cal_x1 - cal_x0);
	*b_gen *= 8;

	return 0;
}

static int hts221_get_sensor_scale(struct hts221_hw *hw,
				   enum iio_chan_type ch_type,
				   int *val, int *val2)
{
	s64 tmp;
	s32 rem, div, data;

	switch (ch_type) {
	case IIO_HUMIDITYRELATIVE:
		data = hw->sensors[HTS221_SENSOR_H].slope;
		div = (1 << 4) * 1000;
		break;
	case IIO_TEMP:
		data = hw->sensors[HTS221_SENSOR_T].slope;
		div = (1 << 6) * 1000;
		break;
	default:
		return -EINVAL;
	}

	tmp = div_s64(data * 1000000000LL, div);
	tmp = div_s64_rem(tmp, 1000000000LL, &rem);

	*val = tmp;
	*val2 = rem;

	return IIO_VAL_INT_PLUS_NANO;
}

static int hts221_get_sensor_offset(struct hts221_hw *hw,
				    enum iio_chan_type ch_type,
				    int *val, int *val2)
{
	s64 tmp;
	s32 rem, div, data;

	switch (ch_type) {
	case IIO_HUMIDITYRELATIVE:
		data = hw->sensors[HTS221_SENSOR_H].b_gen;
		div = hw->sensors[HTS221_SENSOR_H].slope;
		break;
	case IIO_TEMP:
		data = hw->sensors[HTS221_SENSOR_T].b_gen;
		div = hw->sensors[HTS221_SENSOR_T].slope;
		break;
	default:
		return -EINVAL;
	}

	tmp = div_s64(data * 1000000000LL, div);
	tmp = div_s64_rem(tmp, 1000000000LL, &rem);

	*val = tmp;
	*val2 = rem;

	return IIO_VAL_INT_PLUS_NANO;
}

static int hts221_read_oneshot(struct hts221_hw *hw, u8 addr, int *val)
{
	u8 data[HTS221_DATA_SIZE];
	int err;

	err = hts221_set_enable(hw, true);
	if (err < 0)
		return err;

	msleep(50);

	err = hw->tf->read(hw->dev, addr, sizeof(data), data);
	if (err < 0)
		return err;

	hts221_set_enable(hw, false);

	*val = (s16)get_unaligned_le16(data);

	return IIO_VAL_INT;
}

static int hts221_read_raw(struct iio_dev *iio_dev,
			   struct iio_chan_spec const *ch,
			   int *val, int *val2, long mask)
{
	struct hts221_hw *hw = iio_priv(iio_dev);
	int ret;

	ret = iio_device_claim_direct_mode(iio_dev);
	if (ret)
		return ret;

	switch (mask) {
	case IIO_CHAN_INFO_RAW:
		ret = hts221_read_oneshot(hw, ch->address, val);
		break;
	case IIO_CHAN_INFO_SCALE:
		ret = hts221_get_sensor_scale(hw, ch->type, val, val2);
		break;
	case IIO_CHAN_INFO_OFFSET:
		ret = hts221_get_sensor_offset(hw, ch->type, val, val2);
		break;
	case IIO_CHAN_INFO_SAMP_FREQ:
		*val = hw->odr;
		ret = IIO_VAL_INT;
		break;
	case IIO_CHAN_INFO_OVERSAMPLING_RATIO: {
		u8 idx;
		const struct hts221_avg *avg;

		switch (ch->type) {
		case IIO_HUMIDITYRELATIVE:
			avg = &hts221_avg_list[HTS221_SENSOR_H];
			idx = hw->sensors[HTS221_SENSOR_H].cur_avg_idx;
			*val = avg->avg_avl[idx];
			ret = IIO_VAL_INT;
			break;
		case IIO_TEMP:
			avg = &hts221_avg_list[HTS221_SENSOR_T];
			idx = hw->sensors[HTS221_SENSOR_T].cur_avg_idx;
			*val = avg->avg_avl[idx];
			ret = IIO_VAL_INT;
			break;
		default:
			ret = -EINVAL;
			break;
		}
		break;
	}
	default:
		ret = -EINVAL;
		break;
	}

	iio_device_release_direct_mode(iio_dev);

	return ret;
}

static int hts221_write_raw(struct iio_dev *iio_dev,
			    struct iio_chan_spec const *chan,
			    int val, int val2, long mask)
{
	struct hts221_hw *hw = iio_priv(iio_dev);
	int ret;

	ret = iio_device_claim_direct_mode(iio_dev);
	if (ret)
		return ret;

	switch (mask) {
	case IIO_CHAN_INFO_SAMP_FREQ:
		ret = hts221_update_odr(hw, val);
		break;
	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
		switch (chan->type) {
		case IIO_HUMIDITYRELATIVE:
			ret = hts221_update_avg(hw, HTS221_SENSOR_H, val);
			break;
		case IIO_TEMP:
			ret = hts221_update_avg(hw, HTS221_SENSOR_T, val);
			break;
		default:
			ret = -EINVAL;
			break;
		}
		break;
	default:
		ret = -EINVAL;
		break;
	}

	iio_device_release_direct_mode(iio_dev);

	return ret;
}

static int hts221_validate_trigger(struct iio_dev *iio_dev,
				   struct iio_trigger *trig)
{
	struct hts221_hw *hw = iio_priv(iio_dev);

	return hw->trig == trig ? 0 : -EINVAL;
}

static IIO_DEVICE_ATTR(in_humidity_oversampling_ratio_available, S_IRUGO,
		       hts221_sysfs_rh_oversampling_avail, NULL, 0);
static IIO_DEVICE_ATTR(in_temp_oversampling_ratio_available, S_IRUGO,
		       hts221_sysfs_temp_oversampling_avail, NULL, 0);
static IIO_DEV_ATTR_SAMP_FREQ_AVAIL(hts221_sysfs_sampling_freq);

static struct attribute *hts221_attributes[] = {
	&iio_dev_attr_sampling_frequency_available.dev_attr.attr,
	&iio_dev_attr_in_humidity_oversampling_ratio_available.dev_attr.attr,
	&iio_dev_attr_in_temp_oversampling_ratio_available.dev_attr.attr,
	NULL,
};

static const struct attribute_group hts221_attribute_group = {
	.attrs = hts221_attributes,
};

static const struct iio_info hts221_info = {
	.driver_module = THIS_MODULE,
	.attrs = &hts221_attribute_group,
	.read_raw = hts221_read_raw,
	.write_raw = hts221_write_raw,
	.validate_trigger = hts221_validate_trigger,
};

static const unsigned long hts221_scan_masks[] = {0x3, 0x0};

int hts221_probe(struct iio_dev *iio_dev)
{
	struct hts221_hw *hw = iio_priv(iio_dev);
	int err;
	u8 data;

	mutex_init(&hw->lock);

	err = hts221_check_whoami(hw);
	if (err < 0)
		return err;

	iio_dev->modes = INDIO_DIRECT_MODE;
	iio_dev->dev.parent = hw->dev;
	iio_dev->available_scan_masks = hts221_scan_masks;
	iio_dev->channels = hts221_channels;
	iio_dev->num_channels = ARRAY_SIZE(hts221_channels);
	iio_dev->name = HTS221_DEV_NAME;
	iio_dev->info = &hts221_info;

	/* enable Block Data Update */
	err = hts221_write_with_mask(hw, HTS221_REG_CNTRL1_ADDR,
				     HTS221_BDU_MASK, 1);
	if (err < 0)
		return err;

	err = hts221_update_odr(hw, hts221_odr_table[0].hz);
	if (err < 0)
		return err;

	/* configure humidity sensor */
	err = hts221_parse_rh_caldata(hw);
	if (err < 0) {
		dev_err(hw->dev, "failed to get rh calibration data\n");
		return err;
	}

	data = hts221_avg_list[HTS221_SENSOR_H].avg_avl[3];
	err = hts221_update_avg(hw, HTS221_SENSOR_H, data);
	if (err < 0) {
		dev_err(hw->dev, "failed to set rh oversampling ratio\n");
		return err;
	}

	/* configure temperature sensor */
	err = hts221_parse_temp_caldata(hw);
	if (err < 0) {
		dev_err(hw->dev,
			"failed to get temperature calibration data\n");
		return err;
	}

	data = hts221_avg_list[HTS221_SENSOR_T].avg_avl[3];
	err = hts221_update_avg(hw, HTS221_SENSOR_T, data);
	if (err < 0) {
		dev_err(hw->dev,
			"failed to set temperature oversampling ratio\n");
		return err;
	}

	if (hw->irq > 0) {
		err = hts221_allocate_buffers(hw);
		if (err < 0)
			return err;

		err = hts221_allocate_trigger(hw);
		if (err)
			return err;
	}

	return devm_iio_device_register(hw->dev, iio_dev);
}
EXPORT_SYMBOL(hts221_probe);

static int __maybe_unused hts221_suspend(struct device *dev)
{
	struct iio_dev *iio_dev = dev_get_drvdata(dev);
	struct hts221_hw *hw = iio_priv(iio_dev);
	int err;

	err = hts221_write_with_mask(hw, HTS221_REG_CNTRL1_ADDR,
				     HTS221_ENABLE_MASK, false);

	return err < 0 ? err : 0;
}

static int __maybe_unused hts221_resume(struct device *dev)
{
	struct iio_dev *iio_dev = dev_get_drvdata(dev);
	struct hts221_hw *hw = iio_priv(iio_dev);
	int err = 0;

	if (hw->enabled)
		err = hts221_write_with_mask(hw, HTS221_REG_CNTRL1_ADDR,
					     HTS221_ENABLE_MASK, true);

	return err;
}

const struct dev_pm_ops hts221_pm_ops = {
	SET_SYSTEM_SLEEP_PM_OPS(hts221_suspend, hts221_resume)
};
EXPORT_SYMBOL(hts221_pm_ops);

MODULE_AUTHOR("Lorenzo Bianconi <lorenzo.bianconi@st.com>");
MODULE_DESCRIPTION("STMicroelectronics hts221 sensor driver");
MODULE_LICENSE("GPL v2");