xref: /linux/drivers/iio/pressure/dps310.c (revision 55d0969c451159cff86949b38c39171cab962069)
1 // SPDX-License-Identifier: GPL-2.0+
2 // Copyright IBM Corp 2019
3 /*
4  * The DPS310 is a barometric pressure and temperature sensor.
5  * Currently only reading a single temperature is supported by
6  * this driver.
7  *
8  * https://www.infineon.com/dgdl/?fileId=5546d462576f34750157750826c42242
9  *
10  * Temperature calculation:
11  *   c0 * 0.5 + c1 * T_raw / kT °C
12  *
13  * TODO:
14  *  - Optionally support the FIFO
15  */
16 
17 #include <linux/i2c.h>
18 #include <linux/limits.h>
19 #include <linux/math64.h>
20 #include <linux/module.h>
21 #include <linux/regmap.h>
22 
23 #include <linux/iio/iio.h>
24 #include <linux/iio/sysfs.h>
25 
26 #define DPS310_DEV_NAME		"dps310"
27 
28 #define DPS310_PRS_B0		0x00
29 #define DPS310_PRS_B1		0x01
30 #define DPS310_PRS_B2		0x02
31 #define DPS310_TMP_B0		0x03
32 #define DPS310_TMP_B1		0x04
33 #define DPS310_TMP_B2		0x05
34 #define DPS310_PRS_CFG		0x06
35 #define  DPS310_PRS_RATE_BITS	GENMASK(6, 4)
36 #define  DPS310_PRS_PRC_BITS	GENMASK(3, 0)
37 #define DPS310_TMP_CFG		0x07
38 #define  DPS310_TMP_RATE_BITS	GENMASK(6, 4)
39 #define  DPS310_TMP_PRC_BITS	GENMASK(3, 0)
40 #define  DPS310_TMP_EXT		BIT(7)
41 #define DPS310_MEAS_CFG		0x08
42 #define  DPS310_MEAS_CTRL_BITS	GENMASK(2, 0)
43 #define   DPS310_PRS_EN		BIT(0)
44 #define   DPS310_TEMP_EN	BIT(1)
45 #define   DPS310_BACKGROUND	BIT(2)
46 #define  DPS310_PRS_RDY		BIT(4)
47 #define  DPS310_TMP_RDY		BIT(5)
48 #define  DPS310_SENSOR_RDY	BIT(6)
49 #define  DPS310_COEF_RDY	BIT(7)
50 #define DPS310_CFG_REG		0x09
51 #define  DPS310_INT_HL		BIT(7)
52 #define  DPS310_TMP_SHIFT_EN	BIT(3)
53 #define  DPS310_PRS_SHIFT_EN	BIT(4)
54 #define  DPS310_FIFO_EN		BIT(5)
55 #define  DPS310_SPI_EN		BIT(6)
56 #define DPS310_RESET		0x0c
57 #define  DPS310_RESET_MAGIC	0x09
58 #define DPS310_COEF_BASE	0x10
59 
60 /* Make sure sleep time is <= 30ms for usleep_range */
61 #define DPS310_POLL_SLEEP_US(t)		min(30000, (t) / 8)
62 /* Silently handle error in rate value here */
63 #define DPS310_POLL_TIMEOUT_US(rc)	((rc) <= 0 ? 1000000 : 1000000 / (rc))
64 
65 #define DPS310_PRS_BASE		DPS310_PRS_B0
66 #define DPS310_TMP_BASE		DPS310_TMP_B0
67 
68 /*
69  * These values (defined in the spec) indicate how to scale the raw register
70  * values for each level of precision available.
71  */
72 static const int scale_factors[] = {
73 	 524288,
74 	1572864,
75 	3670016,
76 	7864320,
77 	 253952,
78 	 516096,
79 	1040384,
80 	2088960,
81 };
82 
83 struct dps310_data {
84 	struct i2c_client *client;
85 	struct regmap *regmap;
86 	struct mutex lock;	/* Lock for sequential HW access functions */
87 
88 	s32 c0, c1;
89 	s32 c00, c10, c20, c30, c01, c11, c21;
90 	s32 pressure_raw;
91 	s32 temp_raw;
92 	bool timeout_recovery_failed;
93 };
94 
95 static const struct iio_chan_spec dps310_channels[] = {
96 	{
97 		.type = IIO_TEMP,
98 		.info_mask_separate = BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO) |
99 			BIT(IIO_CHAN_INFO_SAMP_FREQ) |
100 			BIT(IIO_CHAN_INFO_PROCESSED),
101 	},
102 	{
103 		.type = IIO_PRESSURE,
104 		.info_mask_separate = BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO) |
105 			BIT(IIO_CHAN_INFO_SAMP_FREQ) |
106 			BIT(IIO_CHAN_INFO_PROCESSED),
107 	},
108 };
109 
110 /* To be called after checking the COEF_RDY bit in MEAS_CFG */
111 static int dps310_get_coefs(struct dps310_data *data)
112 {
113 	int rc;
114 	u8 coef[18];
115 	u32 c0, c1;
116 	u32 c00, c10, c20, c30, c01, c11, c21;
117 
118 	/* Read all sensor calibration coefficients from the COEF registers. */
119 	rc = regmap_bulk_read(data->regmap, DPS310_COEF_BASE, coef,
120 			      sizeof(coef));
121 	if (rc < 0)
122 		return rc;
123 
124 	/*
125 	 * Calculate temperature calibration coefficients c0 and c1. The
126 	 * numbers are 12-bit 2's complement numbers.
127 	 */
128 	c0 = (coef[0] << 4) | (coef[1] >> 4);
129 	data->c0 = sign_extend32(c0, 11);
130 
131 	c1 = ((coef[1] & GENMASK(3, 0)) << 8) | coef[2];
132 	data->c1 = sign_extend32(c1, 11);
133 
134 	/*
135 	 * Calculate pressure calibration coefficients. c00 and c10 are 20 bit
136 	 * 2's complement numbers, while the rest are 16 bit 2's complement
137 	 * numbers.
138 	 */
139 	c00 = (coef[3] << 12) | (coef[4] << 4) | (coef[5] >> 4);
140 	data->c00 = sign_extend32(c00, 19);
141 
142 	c10 = ((coef[5] & GENMASK(3, 0)) << 16) | (coef[6] << 8) | coef[7];
143 	data->c10 = sign_extend32(c10, 19);
144 
145 	c01 = (coef[8] << 8) | coef[9];
146 	data->c01 = sign_extend32(c01, 15);
147 
148 	c11 = (coef[10] << 8) | coef[11];
149 	data->c11 = sign_extend32(c11, 15);
150 
151 	c20 = (coef[12] << 8) | coef[13];
152 	data->c20 = sign_extend32(c20, 15);
153 
154 	c21 = (coef[14] << 8) | coef[15];
155 	data->c21 = sign_extend32(c21, 15);
156 
157 	c30 = (coef[16] << 8) | coef[17];
158 	data->c30 = sign_extend32(c30, 15);
159 
160 	return 0;
161 }
162 
163 /*
164  * Some versions of the chip will read temperatures in the ~60C range when
165  * it's actually ~20C. This is the manufacturer recommended workaround
166  * to correct the issue. The registers used below are undocumented.
167  */
168 static int dps310_temp_workaround(struct dps310_data *data)
169 {
170 	int rc;
171 	int reg;
172 
173 	rc = regmap_read(data->regmap, 0x32, &reg);
174 	if (rc < 0)
175 		return rc;
176 
177 	/*
178 	 * If bit 1 is set then the device is okay, and the workaround does not
179 	 * need to be applied
180 	 */
181 	if (reg & BIT(1))
182 		return 0;
183 
184 	rc = regmap_write(data->regmap, 0x0e, 0xA5);
185 	if (rc)
186 		return rc;
187 
188 	rc = regmap_write(data->regmap, 0x0f, 0x96);
189 	if (rc)
190 		return rc;
191 
192 	rc = regmap_write(data->regmap, 0x62, 0x02);
193 	if (rc)
194 		return rc;
195 
196 	rc = regmap_write(data->regmap, 0x0e, 0x00);
197 	if (rc)
198 		return rc;
199 
200 	return regmap_write(data->regmap, 0x0f, 0x00);
201 }
202 
203 static int dps310_startup(struct dps310_data *data)
204 {
205 	int rc;
206 	int ready;
207 
208 	/*
209 	 * Set up pressure sensor in single sample, one measurement per second
210 	 * mode
211 	 */
212 	rc = regmap_write(data->regmap, DPS310_PRS_CFG, 0);
213 	if (rc)
214 		return rc;
215 
216 	/*
217 	 * Set up external (MEMS) temperature sensor in single sample, one
218 	 * measurement per second mode
219 	 */
220 	rc = regmap_write(data->regmap, DPS310_TMP_CFG, DPS310_TMP_EXT);
221 	if (rc)
222 		return rc;
223 
224 	/* Temp and pressure shifts are disabled when PRC <= 8 */
225 	rc = regmap_write_bits(data->regmap, DPS310_CFG_REG,
226 			       DPS310_PRS_SHIFT_EN | DPS310_TMP_SHIFT_EN, 0);
227 	if (rc)
228 		return rc;
229 
230 	/* MEAS_CFG doesn't update correctly unless first written with 0 */
231 	rc = regmap_write_bits(data->regmap, DPS310_MEAS_CFG,
232 			       DPS310_MEAS_CTRL_BITS, 0);
233 	if (rc)
234 		return rc;
235 
236 	/* Turn on temperature and pressure measurement in the background */
237 	rc = regmap_write_bits(data->regmap, DPS310_MEAS_CFG,
238 			       DPS310_MEAS_CTRL_BITS, DPS310_PRS_EN |
239 			       DPS310_TEMP_EN | DPS310_BACKGROUND);
240 	if (rc)
241 		return rc;
242 
243 	/*
244 	 * Calibration coefficients required for reporting temperature.
245 	 * They are available 40ms after the device has started
246 	 */
247 	rc = regmap_read_poll_timeout(data->regmap, DPS310_MEAS_CFG, ready,
248 				      ready & DPS310_COEF_RDY, 10000, 40000);
249 	if (rc)
250 		return rc;
251 
252 	rc = dps310_get_coefs(data);
253 	if (rc)
254 		return rc;
255 
256 	return dps310_temp_workaround(data);
257 }
258 
259 static int dps310_get_pres_precision(struct dps310_data *data, int *val)
260 {
261 	int reg_val, rc;
262 
263 	rc = regmap_read(data->regmap, DPS310_PRS_CFG, &reg_val);
264 	if (rc < 0)
265 		return rc;
266 
267 	*val = BIT(reg_val & GENMASK(2, 0));
268 
269 	return 0;
270 }
271 
272 static int dps310_get_temp_precision(struct dps310_data *data, int *val)
273 {
274 	int reg_val, rc;
275 
276 	rc = regmap_read(data->regmap, DPS310_TMP_CFG, &reg_val);
277 	if (rc < 0)
278 		return rc;
279 
280 	/*
281 	 * Scale factor is bottom 4 bits of the register, but 1111 is
282 	 * reserved so just grab bottom three
283 	 */
284 	*val = BIT(reg_val & GENMASK(2, 0));
285 
286 	return 0;
287 }
288 
289 /* Called with lock held */
290 static int dps310_set_pres_precision(struct dps310_data *data, int val)
291 {
292 	int rc;
293 	u8 shift_en;
294 
295 	if (val < 0 || val > 128)
296 		return -EINVAL;
297 
298 	shift_en = val >= 16 ? DPS310_PRS_SHIFT_EN : 0;
299 	rc = regmap_write_bits(data->regmap, DPS310_CFG_REG,
300 			       DPS310_PRS_SHIFT_EN, shift_en);
301 	if (rc)
302 		return rc;
303 
304 	return regmap_update_bits(data->regmap, DPS310_PRS_CFG,
305 				  DPS310_PRS_PRC_BITS, ilog2(val));
306 }
307 
308 /* Called with lock held */
309 static int dps310_set_temp_precision(struct dps310_data *data, int val)
310 {
311 	int rc;
312 	u8 shift_en;
313 
314 	if (val < 0 || val > 128)
315 		return -EINVAL;
316 
317 	shift_en = val >= 16 ? DPS310_TMP_SHIFT_EN : 0;
318 	rc = regmap_write_bits(data->regmap, DPS310_CFG_REG,
319 			       DPS310_TMP_SHIFT_EN, shift_en);
320 	if (rc)
321 		return rc;
322 
323 	return regmap_update_bits(data->regmap, DPS310_TMP_CFG,
324 				  DPS310_TMP_PRC_BITS, ilog2(val));
325 }
326 
327 /* Called with lock held */
328 static int dps310_set_pres_samp_freq(struct dps310_data *data, int freq)
329 {
330 	u8 val;
331 
332 	if (freq < 0 || freq > 128)
333 		return -EINVAL;
334 
335 	val = ilog2(freq) << 4;
336 
337 	return regmap_update_bits(data->regmap, DPS310_PRS_CFG,
338 				  DPS310_PRS_RATE_BITS, val);
339 }
340 
341 /* Called with lock held */
342 static int dps310_set_temp_samp_freq(struct dps310_data *data, int freq)
343 {
344 	u8 val;
345 
346 	if (freq < 0 || freq > 128)
347 		return -EINVAL;
348 
349 	val = ilog2(freq) << 4;
350 
351 	return regmap_update_bits(data->regmap, DPS310_TMP_CFG,
352 				  DPS310_TMP_RATE_BITS, val);
353 }
354 
355 static int dps310_get_pres_samp_freq(struct dps310_data *data, int *val)
356 {
357 	int reg_val, rc;
358 
359 	rc = regmap_read(data->regmap, DPS310_PRS_CFG, &reg_val);
360 	if (rc < 0)
361 		return rc;
362 
363 	*val = BIT((reg_val & DPS310_PRS_RATE_BITS) >> 4);
364 
365 	return 0;
366 }
367 
368 static int dps310_get_temp_samp_freq(struct dps310_data *data, int *val)
369 {
370 	int reg_val, rc;
371 
372 	rc = regmap_read(data->regmap, DPS310_TMP_CFG, &reg_val);
373 	if (rc < 0)
374 		return rc;
375 
376 	*val = BIT((reg_val & DPS310_TMP_RATE_BITS) >> 4);
377 
378 	return 0;
379 }
380 
381 static int dps310_get_pres_k(struct dps310_data *data, int *val)
382 {
383 	int reg_val, rc;
384 
385 	rc = regmap_read(data->regmap, DPS310_PRS_CFG, &reg_val);
386 	if (rc < 0)
387 		return rc;
388 
389 	*val = scale_factors[reg_val & GENMASK(2, 0)];
390 
391 	return 0;
392 }
393 
394 static int dps310_get_temp_k(struct dps310_data *data, int *val)
395 {
396 	int reg_val, rc;
397 
398 	rc = regmap_read(data->regmap, DPS310_TMP_CFG, &reg_val);
399 	if (rc < 0)
400 		return rc;
401 
402 	*val = scale_factors[reg_val & GENMASK(2, 0)];
403 
404 	return 0;
405 }
406 
407 static int dps310_reset_wait(struct dps310_data *data)
408 {
409 	int rc;
410 
411 	rc = regmap_write(data->regmap, DPS310_RESET, DPS310_RESET_MAGIC);
412 	if (rc)
413 		return rc;
414 
415 	/* Wait for device chip access: 15ms in specification */
416 	usleep_range(15000, 55000);
417 	return 0;
418 }
419 
420 static int dps310_reset_reinit(struct dps310_data *data)
421 {
422 	int rc;
423 
424 	rc = dps310_reset_wait(data);
425 	if (rc)
426 		return rc;
427 
428 	return dps310_startup(data);
429 }
430 
431 static int dps310_ready_status(struct dps310_data *data, int ready_bit, int timeout)
432 {
433 	int sleep = DPS310_POLL_SLEEP_US(timeout);
434 	int ready;
435 
436 	return regmap_read_poll_timeout(data->regmap, DPS310_MEAS_CFG, ready, ready & ready_bit,
437 					sleep, timeout);
438 }
439 
440 static int dps310_ready(struct dps310_data *data, int ready_bit, int timeout)
441 {
442 	int rc;
443 
444 	rc = dps310_ready_status(data, ready_bit, timeout);
445 	if (rc) {
446 		if (rc == -ETIMEDOUT && !data->timeout_recovery_failed) {
447 			/* Reset and reinitialize the chip. */
448 			if (dps310_reset_reinit(data)) {
449 				data->timeout_recovery_failed = true;
450 			} else {
451 				/* Try again to get sensor ready status. */
452 				if (dps310_ready_status(data, ready_bit, timeout))
453 					data->timeout_recovery_failed = true;
454 				else
455 					return 0;
456 			}
457 		}
458 
459 		return rc;
460 	}
461 
462 	data->timeout_recovery_failed = false;
463 	return 0;
464 }
465 
466 static int dps310_read_pres_raw(struct dps310_data *data)
467 {
468 	int rc;
469 	int rate;
470 	int timeout;
471 	s32 raw;
472 	u8 val[3];
473 
474 	if (mutex_lock_interruptible(&data->lock))
475 		return -EINTR;
476 
477 	rc = dps310_get_pres_samp_freq(data, &rate);
478 	if (rc)
479 		goto done;
480 
481 	timeout = DPS310_POLL_TIMEOUT_US(rate);
482 
483 	/* Poll for sensor readiness; base the timeout upon the sample rate. */
484 	rc = dps310_ready(data, DPS310_PRS_RDY, timeout);
485 	if (rc)
486 		goto done;
487 
488 	rc = regmap_bulk_read(data->regmap, DPS310_PRS_BASE, val, sizeof(val));
489 	if (rc < 0)
490 		goto done;
491 
492 	raw = (val[0] << 16) | (val[1] << 8) | val[2];
493 	data->pressure_raw = sign_extend32(raw, 23);
494 
495 done:
496 	mutex_unlock(&data->lock);
497 	return rc;
498 }
499 
500 /* Called with lock held */
501 static int dps310_read_temp_ready(struct dps310_data *data)
502 {
503 	int rc;
504 	u8 val[3];
505 	s32 raw;
506 
507 	rc = regmap_bulk_read(data->regmap, DPS310_TMP_BASE, val, sizeof(val));
508 	if (rc < 0)
509 		return rc;
510 
511 	raw = (val[0] << 16) | (val[1] << 8) | val[2];
512 	data->temp_raw = sign_extend32(raw, 23);
513 
514 	return 0;
515 }
516 
517 static int dps310_read_temp_raw(struct dps310_data *data)
518 {
519 	int rc;
520 	int rate;
521 	int timeout;
522 
523 	if (mutex_lock_interruptible(&data->lock))
524 		return -EINTR;
525 
526 	rc = dps310_get_temp_samp_freq(data, &rate);
527 	if (rc)
528 		goto done;
529 
530 	timeout = DPS310_POLL_TIMEOUT_US(rate);
531 
532 	/* Poll for sensor readiness; base the timeout upon the sample rate. */
533 	rc = dps310_ready(data, DPS310_TMP_RDY, timeout);
534 	if (rc)
535 		goto done;
536 
537 	rc = dps310_read_temp_ready(data);
538 
539 done:
540 	mutex_unlock(&data->lock);
541 	return rc;
542 }
543 
544 static bool dps310_is_writeable_reg(struct device *dev, unsigned int reg)
545 {
546 	switch (reg) {
547 	case DPS310_PRS_CFG:
548 	case DPS310_TMP_CFG:
549 	case DPS310_MEAS_CFG:
550 	case DPS310_CFG_REG:
551 	case DPS310_RESET:
552 	/* No documentation available on the registers below */
553 	case 0x0e:
554 	case 0x0f:
555 	case 0x62:
556 		return true;
557 	default:
558 		return false;
559 	}
560 }
561 
562 static bool dps310_is_volatile_reg(struct device *dev, unsigned int reg)
563 {
564 	switch (reg) {
565 	case DPS310_PRS_B0:
566 	case DPS310_PRS_B1:
567 	case DPS310_PRS_B2:
568 	case DPS310_TMP_B0:
569 	case DPS310_TMP_B1:
570 	case DPS310_TMP_B2:
571 	case DPS310_MEAS_CFG:
572 	case 0x32:	/* No documentation available on this register */
573 		return true;
574 	default:
575 		return false;
576 	}
577 }
578 
579 static int dps310_write_raw(struct iio_dev *iio,
580 			    struct iio_chan_spec const *chan, int val,
581 			    int val2, long mask)
582 {
583 	int rc;
584 	struct dps310_data *data = iio_priv(iio);
585 
586 	if (mutex_lock_interruptible(&data->lock))
587 		return -EINTR;
588 
589 	switch (mask) {
590 	case IIO_CHAN_INFO_SAMP_FREQ:
591 		switch (chan->type) {
592 		case IIO_PRESSURE:
593 			rc = dps310_set_pres_samp_freq(data, val);
594 			break;
595 
596 		case IIO_TEMP:
597 			rc = dps310_set_temp_samp_freq(data, val);
598 			break;
599 
600 		default:
601 			rc = -EINVAL;
602 			break;
603 		}
604 		break;
605 
606 	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
607 		switch (chan->type) {
608 		case IIO_PRESSURE:
609 			rc = dps310_set_pres_precision(data, val);
610 			break;
611 
612 		case IIO_TEMP:
613 			rc = dps310_set_temp_precision(data, val);
614 			break;
615 
616 		default:
617 			rc = -EINVAL;
618 			break;
619 		}
620 		break;
621 
622 	default:
623 		rc = -EINVAL;
624 		break;
625 	}
626 
627 	mutex_unlock(&data->lock);
628 	return rc;
629 }
630 
631 static int dps310_calculate_pressure(struct dps310_data *data, int *val)
632 {
633 	int i;
634 	int rc;
635 	int t_ready;
636 	int kpi;
637 	int kti;
638 	s64 rem = 0ULL;
639 	s64 pressure = 0ULL;
640 	s64 p;
641 	s64 t;
642 	s64 denoms[7];
643 	s64 nums[7];
644 	s64 rems[7];
645 	s64 kp;
646 	s64 kt;
647 
648 	rc = dps310_get_pres_k(data, &kpi);
649 	if (rc)
650 		return rc;
651 
652 	rc = dps310_get_temp_k(data, &kti);
653 	if (rc)
654 		return rc;
655 
656 	kp = (s64)kpi;
657 	kt = (s64)kti;
658 
659 	/* Refresh temp if it's ready, otherwise just use the latest value */
660 	if (mutex_trylock(&data->lock)) {
661 		rc = regmap_read(data->regmap, DPS310_MEAS_CFG, &t_ready);
662 		if (rc >= 0 && t_ready & DPS310_TMP_RDY)
663 			dps310_read_temp_ready(data);
664 
665 		mutex_unlock(&data->lock);
666 	}
667 
668 	p = (s64)data->pressure_raw;
669 	t = (s64)data->temp_raw;
670 
671 	/* Section 4.9.1 of the DPS310 spec; algebra'd to avoid underflow */
672 	nums[0] = (s64)data->c00;
673 	denoms[0] = 1LL;
674 	nums[1] = p * (s64)data->c10;
675 	denoms[1] = kp;
676 	nums[2] = p * p * (s64)data->c20;
677 	denoms[2] = kp * kp;
678 	nums[3] = p * p * p * (s64)data->c30;
679 	denoms[3] = kp * kp * kp;
680 	nums[4] = t * (s64)data->c01;
681 	denoms[4] = kt;
682 	nums[5] = t * p * (s64)data->c11;
683 	denoms[5] = kp * kt;
684 	nums[6] = t * p * p * (s64)data->c21;
685 	denoms[6] = kp * kp * kt;
686 
687 	/* Kernel lacks a div64_s64_rem function; denoms are all positive */
688 	for (i = 0; i < 7; ++i) {
689 		u64 irem;
690 
691 		if (nums[i] < 0LL) {
692 			pressure -= div64_u64_rem(-nums[i], denoms[i], &irem);
693 			rems[i] = -irem;
694 		} else {
695 			pressure += div64_u64_rem(nums[i], denoms[i], &irem);
696 			rems[i] = (s64)irem;
697 		}
698 	}
699 
700 	/* Increase precision and calculate the remainder sum */
701 	for (i = 0; i < 7; ++i)
702 		rem += div64_s64((s64)rems[i] * 1000000000LL, denoms[i]);
703 
704 	pressure += div_s64(rem, 1000000000LL);
705 	if (pressure < 0LL)
706 		return -ERANGE;
707 
708 	*val = (int)min_t(s64, pressure, INT_MAX);
709 
710 	return 0;
711 }
712 
713 static int dps310_read_pressure(struct dps310_data *data, int *val, int *val2,
714 				long mask)
715 {
716 	int rc;
717 
718 	switch (mask) {
719 	case IIO_CHAN_INFO_SAMP_FREQ:
720 		rc = dps310_get_pres_samp_freq(data, val);
721 		if (rc)
722 			return rc;
723 
724 		return IIO_VAL_INT;
725 
726 	case IIO_CHAN_INFO_PROCESSED:
727 		rc = dps310_read_pres_raw(data);
728 		if (rc)
729 			return rc;
730 
731 		rc = dps310_calculate_pressure(data, val);
732 		if (rc)
733 			return rc;
734 
735 		*val2 = 1000; /* Convert Pa to KPa per IIO ABI */
736 		return IIO_VAL_FRACTIONAL;
737 
738 	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
739 		rc = dps310_get_pres_precision(data, val);
740 		if (rc)
741 			return rc;
742 		return IIO_VAL_INT;
743 
744 	default:
745 		return -EINVAL;
746 	}
747 }
748 
749 static int dps310_calculate_temp(struct dps310_data *data, int *val)
750 {
751 	s64 c0;
752 	s64 t;
753 	int kt, rc;
754 
755 	rc = dps310_get_temp_k(data, &kt);
756 	if (rc)
757 		return rc;
758 
759 	/* Obtain inverse-scaled offset */
760 	c0 = div_s64((s64)kt * (s64)data->c0, 2);
761 
762 	/* Add the offset to the unscaled temperature */
763 	t = c0 + ((s64)data->temp_raw * (s64)data->c1);
764 
765 	/* Convert to milliCelsius and scale the temperature */
766 	*val = (int)div_s64(t * 1000LL, kt);
767 
768 	return 0;
769 }
770 
771 static int dps310_read_temp(struct dps310_data *data, int *val, int *val2,
772 			    long mask)
773 {
774 	int rc;
775 
776 	switch (mask) {
777 	case IIO_CHAN_INFO_SAMP_FREQ:
778 		rc = dps310_get_temp_samp_freq(data, val);
779 		if (rc)
780 			return rc;
781 
782 		return IIO_VAL_INT;
783 
784 	case IIO_CHAN_INFO_PROCESSED:
785 		rc = dps310_read_temp_raw(data);
786 		if (rc)
787 			return rc;
788 
789 		rc = dps310_calculate_temp(data, val);
790 		if (rc)
791 			return rc;
792 
793 		return IIO_VAL_INT;
794 
795 	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
796 		rc = dps310_get_temp_precision(data, val);
797 		if (rc)
798 			return rc;
799 
800 		return IIO_VAL_INT;
801 
802 	default:
803 		return -EINVAL;
804 	}
805 }
806 
807 static int dps310_read_raw(struct iio_dev *iio,
808 			   struct iio_chan_spec const *chan,
809 			   int *val, int *val2, long mask)
810 {
811 	struct dps310_data *data = iio_priv(iio);
812 
813 	switch (chan->type) {
814 	case IIO_PRESSURE:
815 		return dps310_read_pressure(data, val, val2, mask);
816 
817 	case IIO_TEMP:
818 		return dps310_read_temp(data, val, val2, mask);
819 
820 	default:
821 		return -EINVAL;
822 	}
823 }
824 
825 static void dps310_reset(void *action_data)
826 {
827 	struct dps310_data *data = action_data;
828 
829 	dps310_reset_wait(data);
830 }
831 
832 static const struct regmap_config dps310_regmap_config = {
833 	.reg_bits = 8,
834 	.val_bits = 8,
835 	.writeable_reg = dps310_is_writeable_reg,
836 	.volatile_reg = dps310_is_volatile_reg,
837 	.cache_type = REGCACHE_RBTREE,
838 	.max_register = 0x62, /* No documentation available on this register */
839 };
840 
841 static const struct iio_info dps310_info = {
842 	.read_raw = dps310_read_raw,
843 	.write_raw = dps310_write_raw,
844 };
845 
846 static int dps310_probe(struct i2c_client *client)
847 {
848 	const struct i2c_device_id *id = i2c_client_get_device_id(client);
849 	struct dps310_data *data;
850 	struct iio_dev *iio;
851 	int rc;
852 
853 	iio = devm_iio_device_alloc(&client->dev,  sizeof(*data));
854 	if (!iio)
855 		return -ENOMEM;
856 
857 	data = iio_priv(iio);
858 	data->client = client;
859 	mutex_init(&data->lock);
860 
861 	iio->name = id->name;
862 	iio->channels = dps310_channels;
863 	iio->num_channels = ARRAY_SIZE(dps310_channels);
864 	iio->info = &dps310_info;
865 	iio->modes = INDIO_DIRECT_MODE;
866 
867 	data->regmap = devm_regmap_init_i2c(client, &dps310_regmap_config);
868 	if (IS_ERR(data->regmap))
869 		return PTR_ERR(data->regmap);
870 
871 	/* Register to run the device reset when the device is removed */
872 	rc = devm_add_action_or_reset(&client->dev, dps310_reset, data);
873 	if (rc)
874 		return rc;
875 
876 	rc = dps310_startup(data);
877 	if (rc)
878 		return rc;
879 
880 	rc = devm_iio_device_register(&client->dev, iio);
881 	if (rc)
882 		return rc;
883 
884 	i2c_set_clientdata(client, iio);
885 
886 	return 0;
887 }
888 
889 static const struct i2c_device_id dps310_id[] = {
890 	{ DPS310_DEV_NAME },
891 	{}
892 };
893 MODULE_DEVICE_TABLE(i2c, dps310_id);
894 
895 static const struct acpi_device_id dps310_acpi_match[] = {
896 	{ "IFX3100" },
897 	{}
898 };
899 MODULE_DEVICE_TABLE(acpi, dps310_acpi_match);
900 
901 static struct i2c_driver dps310_driver = {
902 	.driver = {
903 		.name = DPS310_DEV_NAME,
904 		.acpi_match_table = dps310_acpi_match,
905 	},
906 	.probe = dps310_probe,
907 	.id_table = dps310_id,
908 };
909 module_i2c_driver(dps310_driver);
910 
911 MODULE_AUTHOR("Joel Stanley <joel@jms.id.au>");
912 MODULE_DESCRIPTION("Infineon DPS310 pressure and temperature sensor");
913 MODULE_LICENSE("GPL v2");
914