xref: /openbmc/linux/drivers/iio/pressure/dps310.c (revision abb84c46)
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)
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)
260 {
261 	int rc;
262 	int val;
263 
264 	rc = regmap_read(data->regmap, DPS310_PRS_CFG, &val);
265 	if (rc < 0)
266 		return rc;
267 
268 	return BIT(val & GENMASK(2, 0));
269 }
270 
271 static int dps310_get_temp_precision(struct dps310_data *data)
272 {
273 	int rc;
274 	int val;
275 
276 	rc = regmap_read(data->regmap, DPS310_TMP_CFG, &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 	return BIT(val & GENMASK(2, 0));
285 }
286 
287 /* Called with lock held */
288 static int dps310_set_pres_precision(struct dps310_data *data, int val)
289 {
290 	int rc;
291 	u8 shift_en;
292 
293 	if (val < 0 || val > 128)
294 		return -EINVAL;
295 
296 	shift_en = val >= 16 ? DPS310_PRS_SHIFT_EN : 0;
297 	rc = regmap_write_bits(data->regmap, DPS310_CFG_REG,
298 			       DPS310_PRS_SHIFT_EN, shift_en);
299 	if (rc)
300 		return rc;
301 
302 	return regmap_update_bits(data->regmap, DPS310_PRS_CFG,
303 				  DPS310_PRS_PRC_BITS, ilog2(val));
304 }
305 
306 /* Called with lock held */
307 static int dps310_set_temp_precision(struct dps310_data *data, int val)
308 {
309 	int rc;
310 	u8 shift_en;
311 
312 	if (val < 0 || val > 128)
313 		return -EINVAL;
314 
315 	shift_en = val >= 16 ? DPS310_TMP_SHIFT_EN : 0;
316 	rc = regmap_write_bits(data->regmap, DPS310_CFG_REG,
317 			       DPS310_TMP_SHIFT_EN, shift_en);
318 	if (rc)
319 		return rc;
320 
321 	return regmap_update_bits(data->regmap, DPS310_TMP_CFG,
322 				  DPS310_TMP_PRC_BITS, ilog2(val));
323 }
324 
325 /* Called with lock held */
326 static int dps310_set_pres_samp_freq(struct dps310_data *data, int freq)
327 {
328 	u8 val;
329 
330 	if (freq < 0 || freq > 128)
331 		return -EINVAL;
332 
333 	val = ilog2(freq) << 4;
334 
335 	return regmap_update_bits(data->regmap, DPS310_PRS_CFG,
336 				  DPS310_PRS_RATE_BITS, val);
337 }
338 
339 /* Called with lock held */
340 static int dps310_set_temp_samp_freq(struct dps310_data *data, int freq)
341 {
342 	u8 val;
343 
344 	if (freq < 0 || freq > 128)
345 		return -EINVAL;
346 
347 	val = ilog2(freq) << 4;
348 
349 	return regmap_update_bits(data->regmap, DPS310_TMP_CFG,
350 				  DPS310_TMP_RATE_BITS, val);
351 }
352 
353 static int dps310_get_pres_samp_freq(struct dps310_data *data)
354 {
355 	int rc;
356 	int val;
357 
358 	rc = regmap_read(data->regmap, DPS310_PRS_CFG, &val);
359 	if (rc < 0)
360 		return rc;
361 
362 	return BIT((val & DPS310_PRS_RATE_BITS) >> 4);
363 }
364 
365 static int dps310_get_temp_samp_freq(struct dps310_data *data)
366 {
367 	int rc;
368 	int val;
369 
370 	rc = regmap_read(data->regmap, DPS310_TMP_CFG, &val);
371 	if (rc < 0)
372 		return rc;
373 
374 	return BIT((val & DPS310_TMP_RATE_BITS) >> 4);
375 }
376 
377 static int dps310_get_pres_k(struct dps310_data *data)
378 {
379 	int rc = dps310_get_pres_precision(data);
380 
381 	if (rc < 0)
382 		return rc;
383 
384 	return scale_factors[ilog2(rc)];
385 }
386 
387 static int dps310_get_temp_k(struct dps310_data *data)
388 {
389 	int rc = dps310_get_temp_precision(data);
390 
391 	if (rc < 0)
392 		return rc;
393 
394 	return scale_factors[ilog2(rc)];
395 }
396 
397 static int dps310_reset_wait(struct dps310_data *data)
398 {
399 	int rc;
400 
401 	rc = regmap_write(data->regmap, DPS310_RESET, DPS310_RESET_MAGIC);
402 	if (rc)
403 		return rc;
404 
405 	/* Wait for device chip access: 15ms in specification */
406 	usleep_range(15000, 55000);
407 	return 0;
408 }
409 
410 static int dps310_reset_reinit(struct dps310_data *data)
411 {
412 	int rc;
413 
414 	rc = dps310_reset_wait(data);
415 	if (rc)
416 		return rc;
417 
418 	return dps310_startup(data);
419 }
420 
421 static int dps310_ready_status(struct dps310_data *data, int ready_bit, int timeout)
422 {
423 	int sleep = DPS310_POLL_SLEEP_US(timeout);
424 	int ready;
425 
426 	return regmap_read_poll_timeout(data->regmap, DPS310_MEAS_CFG, ready, ready & ready_bit,
427 					sleep, timeout);
428 }
429 
430 static int dps310_ready(struct dps310_data *data, int ready_bit, int timeout)
431 {
432 	int rc;
433 
434 	rc = dps310_ready_status(data, ready_bit, timeout);
435 	if (rc) {
436 		if (rc == -ETIMEDOUT && !data->timeout_recovery_failed) {
437 			/* Reset and reinitialize the chip. */
438 			if (dps310_reset_reinit(data)) {
439 				data->timeout_recovery_failed = true;
440 			} else {
441 				/* Try again to get sensor ready status. */
442 				if (dps310_ready_status(data, ready_bit, timeout))
443 					data->timeout_recovery_failed = true;
444 				else
445 					return 0;
446 			}
447 		}
448 
449 		return rc;
450 	}
451 
452 	data->timeout_recovery_failed = false;
453 	return 0;
454 }
455 
456 static int dps310_read_pres_raw(struct dps310_data *data)
457 {
458 	int rc;
459 	int rate;
460 	int timeout;
461 	s32 raw;
462 	u8 val[3];
463 
464 	if (mutex_lock_interruptible(&data->lock))
465 		return -EINTR;
466 
467 	rate = dps310_get_pres_samp_freq(data);
468 	timeout = DPS310_POLL_TIMEOUT_US(rate);
469 
470 	/* Poll for sensor readiness; base the timeout upon the sample rate. */
471 	rc = dps310_ready(data, DPS310_PRS_RDY, timeout);
472 	if (rc)
473 		goto done;
474 
475 	rc = regmap_bulk_read(data->regmap, DPS310_PRS_BASE, val, sizeof(val));
476 	if (rc < 0)
477 		goto done;
478 
479 	raw = (val[0] << 16) | (val[1] << 8) | val[2];
480 	data->pressure_raw = sign_extend32(raw, 23);
481 
482 done:
483 	mutex_unlock(&data->lock);
484 	return rc;
485 }
486 
487 /* Called with lock held */
488 static int dps310_read_temp_ready(struct dps310_data *data)
489 {
490 	int rc;
491 	u8 val[3];
492 	s32 raw;
493 
494 	rc = regmap_bulk_read(data->regmap, DPS310_TMP_BASE, val, sizeof(val));
495 	if (rc < 0)
496 		return rc;
497 
498 	raw = (val[0] << 16) | (val[1] << 8) | val[2];
499 	data->temp_raw = sign_extend32(raw, 23);
500 
501 	return 0;
502 }
503 
504 static int dps310_read_temp_raw(struct dps310_data *data)
505 {
506 	int rc;
507 	int rate;
508 	int timeout;
509 
510 	if (mutex_lock_interruptible(&data->lock))
511 		return -EINTR;
512 
513 	rate = dps310_get_temp_samp_freq(data);
514 	timeout = DPS310_POLL_TIMEOUT_US(rate);
515 
516 	/* Poll for sensor readiness; base the timeout upon the sample rate. */
517 	rc = dps310_ready(data, DPS310_TMP_RDY, timeout);
518 	if (rc)
519 		goto done;
520 
521 	rc = dps310_read_temp_ready(data);
522 
523 done:
524 	mutex_unlock(&data->lock);
525 	return rc;
526 }
527 
528 static bool dps310_is_writeable_reg(struct device *dev, unsigned int reg)
529 {
530 	switch (reg) {
531 	case DPS310_PRS_CFG:
532 	case DPS310_TMP_CFG:
533 	case DPS310_MEAS_CFG:
534 	case DPS310_CFG_REG:
535 	case DPS310_RESET:
536 	/* No documentation available on the registers below */
537 	case 0x0e:
538 	case 0x0f:
539 	case 0x62:
540 		return true;
541 	default:
542 		return false;
543 	}
544 }
545 
546 static bool dps310_is_volatile_reg(struct device *dev, unsigned int reg)
547 {
548 	switch (reg) {
549 	case DPS310_PRS_B0:
550 	case DPS310_PRS_B1:
551 	case DPS310_PRS_B2:
552 	case DPS310_TMP_B0:
553 	case DPS310_TMP_B1:
554 	case DPS310_TMP_B2:
555 	case DPS310_MEAS_CFG:
556 	case 0x32:	/* No documentation available on this register */
557 		return true;
558 	default:
559 		return false;
560 	}
561 }
562 
563 static int dps310_write_raw(struct iio_dev *iio,
564 			    struct iio_chan_spec const *chan, int val,
565 			    int val2, long mask)
566 {
567 	int rc;
568 	struct dps310_data *data = iio_priv(iio);
569 
570 	if (mutex_lock_interruptible(&data->lock))
571 		return -EINTR;
572 
573 	switch (mask) {
574 	case IIO_CHAN_INFO_SAMP_FREQ:
575 		switch (chan->type) {
576 		case IIO_PRESSURE:
577 			rc = dps310_set_pres_samp_freq(data, val);
578 			break;
579 
580 		case IIO_TEMP:
581 			rc = dps310_set_temp_samp_freq(data, val);
582 			break;
583 
584 		default:
585 			rc = -EINVAL;
586 			break;
587 		}
588 		break;
589 
590 	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
591 		switch (chan->type) {
592 		case IIO_PRESSURE:
593 			rc = dps310_set_pres_precision(data, val);
594 			break;
595 
596 		case IIO_TEMP:
597 			rc = dps310_set_temp_precision(data, val);
598 			break;
599 
600 		default:
601 			rc = -EINVAL;
602 			break;
603 		}
604 		break;
605 
606 	default:
607 		rc = -EINVAL;
608 		break;
609 	}
610 
611 	mutex_unlock(&data->lock);
612 	return rc;
613 }
614 
615 static int dps310_calculate_pressure(struct dps310_data *data)
616 {
617 	int i;
618 	int rc;
619 	int t_ready;
620 	int kpi = dps310_get_pres_k(data);
621 	int kti = dps310_get_temp_k(data);
622 	s64 rem = 0ULL;
623 	s64 pressure = 0ULL;
624 	s64 p;
625 	s64 t;
626 	s64 denoms[7];
627 	s64 nums[7];
628 	s64 rems[7];
629 	s64 kp;
630 	s64 kt;
631 
632 	if (kpi < 0)
633 		return kpi;
634 
635 	if (kti < 0)
636 		return kti;
637 
638 	kp = (s64)kpi;
639 	kt = (s64)kti;
640 
641 	/* Refresh temp if it's ready, otherwise just use the latest value */
642 	if (mutex_trylock(&data->lock)) {
643 		rc = regmap_read(data->regmap, DPS310_MEAS_CFG, &t_ready);
644 		if (rc >= 0 && t_ready & DPS310_TMP_RDY)
645 			dps310_read_temp_ready(data);
646 
647 		mutex_unlock(&data->lock);
648 	}
649 
650 	p = (s64)data->pressure_raw;
651 	t = (s64)data->temp_raw;
652 
653 	/* Section 4.9.1 of the DPS310 spec; algebra'd to avoid underflow */
654 	nums[0] = (s64)data->c00;
655 	denoms[0] = 1LL;
656 	nums[1] = p * (s64)data->c10;
657 	denoms[1] = kp;
658 	nums[2] = p * p * (s64)data->c20;
659 	denoms[2] = kp * kp;
660 	nums[3] = p * p * p * (s64)data->c30;
661 	denoms[3] = kp * kp * kp;
662 	nums[4] = t * (s64)data->c01;
663 	denoms[4] = kt;
664 	nums[5] = t * p * (s64)data->c11;
665 	denoms[5] = kp * kt;
666 	nums[6] = t * p * p * (s64)data->c21;
667 	denoms[6] = kp * kp * kt;
668 
669 	/* Kernel lacks a div64_s64_rem function; denoms are all positive */
670 	for (i = 0; i < 7; ++i) {
671 		u64 irem;
672 
673 		if (nums[i] < 0LL) {
674 			pressure -= div64_u64_rem(-nums[i], denoms[i], &irem);
675 			rems[i] = -irem;
676 		} else {
677 			pressure += div64_u64_rem(nums[i], denoms[i], &irem);
678 			rems[i] = (s64)irem;
679 		}
680 	}
681 
682 	/* Increase precision and calculate the remainder sum */
683 	for (i = 0; i < 7; ++i)
684 		rem += div64_s64((s64)rems[i] * 1000000000LL, denoms[i]);
685 
686 	pressure += div_s64(rem, 1000000000LL);
687 	if (pressure < 0LL)
688 		return -ERANGE;
689 
690 	return (int)min_t(s64, pressure, INT_MAX);
691 }
692 
693 static int dps310_read_pressure(struct dps310_data *data, int *val, int *val2,
694 				long mask)
695 {
696 	int rc;
697 
698 	switch (mask) {
699 	case IIO_CHAN_INFO_SAMP_FREQ:
700 		rc = dps310_get_pres_samp_freq(data);
701 		if (rc < 0)
702 			return rc;
703 
704 		*val = rc;
705 		return IIO_VAL_INT;
706 
707 	case IIO_CHAN_INFO_PROCESSED:
708 		rc = dps310_read_pres_raw(data);
709 		if (rc)
710 			return rc;
711 
712 		rc = dps310_calculate_pressure(data);
713 		if (rc < 0)
714 			return rc;
715 
716 		*val = rc;
717 		*val2 = 1000; /* Convert Pa to KPa per IIO ABI */
718 		return IIO_VAL_FRACTIONAL;
719 
720 	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
721 		rc = dps310_get_pres_precision(data);
722 		if (rc < 0)
723 			return rc;
724 
725 		*val = rc;
726 		return IIO_VAL_INT;
727 
728 	default:
729 		return -EINVAL;
730 	}
731 }
732 
733 static int dps310_calculate_temp(struct dps310_data *data, int *val)
734 {
735 	s64 c0;
736 	s64 t;
737 	int kt = dps310_get_temp_k(data);
738 
739 	if (kt < 0)
740 		return kt;
741 
742 	/* Obtain inverse-scaled offset */
743 	c0 = div_s64((s64)kt * (s64)data->c0, 2);
744 
745 	/* Add the offset to the unscaled temperature */
746 	t = c0 + ((s64)data->temp_raw * (s64)data->c1);
747 
748 	/* Convert to milliCelsius and scale the temperature */
749 	*val = (int)div_s64(t * 1000LL, kt);
750 
751 	return 0;
752 }
753 
754 static int dps310_read_temp(struct dps310_data *data, int *val, int *val2,
755 			    long mask)
756 {
757 	int rc;
758 
759 	switch (mask) {
760 	case IIO_CHAN_INFO_SAMP_FREQ:
761 		rc = dps310_get_temp_samp_freq(data);
762 		if (rc < 0)
763 			return rc;
764 
765 		*val = rc;
766 		return IIO_VAL_INT;
767 
768 	case IIO_CHAN_INFO_PROCESSED:
769 		rc = dps310_read_temp_raw(data);
770 		if (rc)
771 			return rc;
772 
773 		rc = dps310_calculate_temp(data, val);
774 		if (rc)
775 			return rc;
776 
777 		return IIO_VAL_INT;
778 
779 	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
780 		rc = dps310_get_temp_precision(data);
781 		if (rc < 0)
782 			return rc;
783 
784 		*val = rc;
785 		return IIO_VAL_INT;
786 
787 	default:
788 		return -EINVAL;
789 	}
790 }
791 
792 static int dps310_read_raw(struct iio_dev *iio,
793 			   struct iio_chan_spec const *chan,
794 			   int *val, int *val2, long mask)
795 {
796 	struct dps310_data *data = iio_priv(iio);
797 
798 	switch (chan->type) {
799 	case IIO_PRESSURE:
800 		return dps310_read_pressure(data, val, val2, mask);
801 
802 	case IIO_TEMP:
803 		return dps310_read_temp(data, val, val2, mask);
804 
805 	default:
806 		return -EINVAL;
807 	}
808 }
809 
810 static void dps310_reset(void *action_data)
811 {
812 	struct dps310_data *data = action_data;
813 
814 	dps310_reset_wait(data);
815 }
816 
817 static const struct regmap_config dps310_regmap_config = {
818 	.reg_bits = 8,
819 	.val_bits = 8,
820 	.writeable_reg = dps310_is_writeable_reg,
821 	.volatile_reg = dps310_is_volatile_reg,
822 	.cache_type = REGCACHE_RBTREE,
823 	.max_register = 0x62, /* No documentation available on this register */
824 };
825 
826 static const struct iio_info dps310_info = {
827 	.read_raw = dps310_read_raw,
828 	.write_raw = dps310_write_raw,
829 };
830 
831 static int dps310_probe(struct i2c_client *client)
832 {
833 	const struct i2c_device_id *id = i2c_client_get_device_id(client);
834 	struct dps310_data *data;
835 	struct iio_dev *iio;
836 	int rc;
837 
838 	iio = devm_iio_device_alloc(&client->dev,  sizeof(*data));
839 	if (!iio)
840 		return -ENOMEM;
841 
842 	data = iio_priv(iio);
843 	data->client = client;
844 	mutex_init(&data->lock);
845 
846 	iio->name = id->name;
847 	iio->channels = dps310_channels;
848 	iio->num_channels = ARRAY_SIZE(dps310_channels);
849 	iio->info = &dps310_info;
850 	iio->modes = INDIO_DIRECT_MODE;
851 
852 	data->regmap = devm_regmap_init_i2c(client, &dps310_regmap_config);
853 	if (IS_ERR(data->regmap))
854 		return PTR_ERR(data->regmap);
855 
856 	/* Register to run the device reset when the device is removed */
857 	rc = devm_add_action_or_reset(&client->dev, dps310_reset, data);
858 	if (rc)
859 		return rc;
860 
861 	rc = dps310_startup(data);
862 	if (rc)
863 		return rc;
864 
865 	rc = devm_iio_device_register(&client->dev, iio);
866 	if (rc)
867 		return rc;
868 
869 	i2c_set_clientdata(client, iio);
870 
871 	return 0;
872 }
873 
874 static const struct i2c_device_id dps310_id[] = {
875 	{ DPS310_DEV_NAME, 0 },
876 	{}
877 };
878 MODULE_DEVICE_TABLE(i2c, dps310_id);
879 
880 static const struct acpi_device_id dps310_acpi_match[] = {
881 	{ "IFX3100" },
882 	{}
883 };
884 MODULE_DEVICE_TABLE(acpi, dps310_acpi_match);
885 
886 static struct i2c_driver dps310_driver = {
887 	.driver = {
888 		.name = DPS310_DEV_NAME,
889 		.acpi_match_table = dps310_acpi_match,
890 	},
891 	.probe = dps310_probe,
892 	.id_table = dps310_id,
893 };
894 module_i2c_driver(dps310_driver);
895 
896 MODULE_AUTHOR("Joel Stanley <joel@jms.id.au>");
897 MODULE_DESCRIPTION("Infineon DPS310 pressure and temperature sensor");
898 MODULE_LICENSE("GPL v2");
899