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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * max31827.c - Support for Maxim Low-Power Switch
4 *
5 * Copyright (c) 2023 Daniel Matyas <daniel.matyas@analog.com>
6 */
7
8#include <linux/bitfield.h>
9#include <linux/bitops.h>
10#include <linux/delay.h>
11#include <linux/hwmon.h>
12#include <linux/i2c.h>
13#include <linux/mutex.h>
14#include <linux/of_device.h>
15#include <linux/regmap.h>
16#include <linux/regulator/consumer.h>
17
18#define MAX31827_T_REG 0x0
19#define MAX31827_CONFIGURATION_REG 0x2
20#define MAX31827_TH_REG 0x4
21#define MAX31827_TL_REG 0x6
22#define MAX31827_TH_HYST_REG 0x8
23#define MAX31827_TL_HYST_REG 0xA
24
25#define MAX31827_CONFIGURATION_1SHOT_MASK BIT(0)
26#define MAX31827_CONFIGURATION_CNV_RATE_MASK GENMASK(3, 1)
27#define MAX31827_CONFIGURATION_TIMEOUT_MASK BIT(5)
28#define MAX31827_CONFIGURATION_RESOLUTION_MASK GENMASK(7, 6)
29#define MAX31827_CONFIGURATION_ALRM_POL_MASK BIT(8)
30#define MAX31827_CONFIGURATION_COMP_INT_MASK BIT(9)
31#define MAX31827_CONFIGURATION_FLT_Q_MASK GENMASK(11, 10)
32#define MAX31827_CONFIGURATION_U_TEMP_STAT_MASK BIT(14)
33#define MAX31827_CONFIGURATION_O_TEMP_STAT_MASK BIT(15)
34
35#define MAX31827_ALRM_POL_LOW 0x0
36#define MAX31827_ALRM_POL_HIGH 0x1
37#define MAX31827_FLT_Q_1 0x0
38#define MAX31827_FLT_Q_4 0x2
39
40#define MAX31827_8_BIT_CNV_TIME 9
41#define MAX31827_9_BIT_CNV_TIME 18
42#define MAX31827_10_BIT_CNV_TIME 35
43#define MAX31827_12_BIT_CNV_TIME 140
44
45#define MAX31827_16_BIT_TO_M_DGR(x) (sign_extend32(x, 15) * 1000 / 16)
46#define MAX31827_M_DGR_TO_16_BIT(x) (((x) << 4) / 1000)
47#define MAX31827_DEVICE_ENABLE(x) ((x) ? 0xA : 0x0)
48
49enum chips { max31827 = 1, max31828, max31829 };
50
51enum max31827_cnv {
52 MAX31827_CNV_1_DIV_64_HZ = 1,
53 MAX31827_CNV_1_DIV_32_HZ,
54 MAX31827_CNV_1_DIV_16_HZ,
55 MAX31827_CNV_1_DIV_4_HZ,
56 MAX31827_CNV_1_HZ,
57 MAX31827_CNV_4_HZ,
58 MAX31827_CNV_8_HZ,
59};
60
61static const u16 max31827_conversions[] = {
62 [MAX31827_CNV_1_DIV_64_HZ] = 64000,
63 [MAX31827_CNV_1_DIV_32_HZ] = 32000,
64 [MAX31827_CNV_1_DIV_16_HZ] = 16000,
65 [MAX31827_CNV_1_DIV_4_HZ] = 4000,
66 [MAX31827_CNV_1_HZ] = 1000,
67 [MAX31827_CNV_4_HZ] = 250,
68 [MAX31827_CNV_8_HZ] = 125,
69};
70
71enum max31827_resolution {
72 MAX31827_RES_8_BIT = 0,
73 MAX31827_RES_9_BIT,
74 MAX31827_RES_10_BIT,
75 MAX31827_RES_12_BIT,
76};
77
78static const u16 max31827_resolutions[] = {
79 [MAX31827_RES_8_BIT] = 1000,
80 [MAX31827_RES_9_BIT] = 500,
81 [MAX31827_RES_10_BIT] = 250,
82 [MAX31827_RES_12_BIT] = 62,
83};
84
85static const u16 max31827_conv_times[] = {
86 [MAX31827_RES_8_BIT] = MAX31827_8_BIT_CNV_TIME,
87 [MAX31827_RES_9_BIT] = MAX31827_9_BIT_CNV_TIME,
88 [MAX31827_RES_10_BIT] = MAX31827_10_BIT_CNV_TIME,
89 [MAX31827_RES_12_BIT] = MAX31827_12_BIT_CNV_TIME,
90};
91
92struct max31827_state {
93 /*
94 * Prevent simultaneous access to the i2c client.
95 */
96 struct mutex lock;
97 struct regmap *regmap;
98 bool enable;
99 unsigned int resolution;
100 unsigned int update_interval;
101};
102
103static const struct regmap_config max31827_regmap = {
104 .reg_bits = 8,
105 .val_bits = 16,
106 .max_register = 0xA,
107};
108
109static int shutdown_write(struct max31827_state *st, unsigned int reg,
110 unsigned int mask, unsigned int val)
111{
112 unsigned int cfg;
113 unsigned int cnv_rate;
114 int ret;
115
116 /*
117 * Before the Temperature Threshold Alarm, Alarm Hysteresis Threshold
118 * and Resolution bits from Configuration register are changed over I2C,
119 * the part must be in shutdown mode.
120 *
121 * Mutex is used to ensure, that some other process doesn't change the
122 * configuration register.
123 */
124 mutex_lock(&st->lock);
125
126 if (!st->enable) {
127 if (!mask)
128 ret = regmap_write(st->regmap, reg, val);
129 else
130 ret = regmap_update_bits(st->regmap, reg, mask, val);
131 goto unlock;
132 }
133
134 ret = regmap_read(st->regmap, MAX31827_CONFIGURATION_REG, &cfg);
135 if (ret)
136 goto unlock;
137
138 cnv_rate = MAX31827_CONFIGURATION_CNV_RATE_MASK & cfg;
139 cfg = cfg & ~(MAX31827_CONFIGURATION_1SHOT_MASK |
140 MAX31827_CONFIGURATION_CNV_RATE_MASK);
141 ret = regmap_write(st->regmap, MAX31827_CONFIGURATION_REG, cfg);
142 if (ret)
143 goto unlock;
144
145 if (!mask)
146 ret = regmap_write(st->regmap, reg, val);
147 else
148 ret = regmap_update_bits(st->regmap, reg, mask, val);
149
150 if (ret)
151 goto unlock;
152
153 ret = regmap_update_bits(st->regmap, MAX31827_CONFIGURATION_REG,
154 MAX31827_CONFIGURATION_CNV_RATE_MASK,
155 cnv_rate);
156
157unlock:
158 mutex_unlock(&st->lock);
159 return ret;
160}
161
162static int write_alarm_val(struct max31827_state *st, unsigned int reg,
163 long val)
164{
165 val = MAX31827_M_DGR_TO_16_BIT(val);
166
167 return shutdown_write(st, reg, 0, val);
168}
169
170static umode_t max31827_is_visible(const void *state,
171 enum hwmon_sensor_types type, u32 attr,
172 int channel)
173{
174 if (type == hwmon_temp) {
175 switch (attr) {
176 case hwmon_temp_enable:
177 case hwmon_temp_max:
178 case hwmon_temp_min:
179 case hwmon_temp_max_hyst:
180 case hwmon_temp_min_hyst:
181 return 0644;
182 case hwmon_temp_input:
183 case hwmon_temp_min_alarm:
184 case hwmon_temp_max_alarm:
185 return 0444;
186 default:
187 return 0;
188 }
189 } else if (type == hwmon_chip) {
190 if (attr == hwmon_chip_update_interval)
191 return 0644;
192 }
193
194 return 0;
195}
196
197static int max31827_read(struct device *dev, enum hwmon_sensor_types type,
198 u32 attr, int channel, long *val)
199{
200 struct max31827_state *st = dev_get_drvdata(dev);
201 unsigned int uval;
202 int ret = 0;
203
204 switch (type) {
205 case hwmon_temp:
206 switch (attr) {
207 case hwmon_temp_enable:
208 ret = regmap_read(st->regmap,
209 MAX31827_CONFIGURATION_REG, &uval);
210 if (ret)
211 break;
212
213 uval = FIELD_GET(MAX31827_CONFIGURATION_1SHOT_MASK |
214 MAX31827_CONFIGURATION_CNV_RATE_MASK,
215 uval);
216 *val = !!uval;
217
218 break;
219 case hwmon_temp_input:
220 mutex_lock(&st->lock);
221
222 if (!st->enable) {
223 /*
224 * This operation requires mutex protection,
225 * because the chip configuration should not
226 * be changed during the conversion process.
227 */
228
229 ret = regmap_update_bits(st->regmap,
230 MAX31827_CONFIGURATION_REG,
231 MAX31827_CONFIGURATION_1SHOT_MASK,
232 1);
233 if (ret) {
234 mutex_unlock(&st->lock);
235 return ret;
236 }
237 msleep(max31827_conv_times[st->resolution]);
238 }
239
240 /*
241 * For 12-bit resolution the conversion time is 140 ms,
242 * thus an additional 15 ms is needed to complete the
243 * conversion: 125 ms + 15 ms = 140 ms
244 */
245 if (max31827_resolutions[st->resolution] == 12 &&
246 st->update_interval == 125)
247 usleep_range(15000, 20000);
248
249 ret = regmap_read(st->regmap, MAX31827_T_REG, &uval);
250
251 mutex_unlock(&st->lock);
252
253 if (ret)
254 break;
255
256 *val = MAX31827_16_BIT_TO_M_DGR(uval);
257
258 break;
259 case hwmon_temp_max:
260 ret = regmap_read(st->regmap, MAX31827_TH_REG, &uval);
261 if (ret)
262 break;
263
264 *val = MAX31827_16_BIT_TO_M_DGR(uval);
265 break;
266 case hwmon_temp_max_hyst:
267 ret = regmap_read(st->regmap, MAX31827_TH_HYST_REG,
268 &uval);
269 if (ret)
270 break;
271
272 *val = MAX31827_16_BIT_TO_M_DGR(uval);
273 break;
274 case hwmon_temp_max_alarm:
275 ret = regmap_read(st->regmap,
276 MAX31827_CONFIGURATION_REG, &uval);
277 if (ret)
278 break;
279
280 *val = FIELD_GET(MAX31827_CONFIGURATION_O_TEMP_STAT_MASK,
281 uval);
282 break;
283 case hwmon_temp_min:
284 ret = regmap_read(st->regmap, MAX31827_TL_REG, &uval);
285 if (ret)
286 break;
287
288 *val = MAX31827_16_BIT_TO_M_DGR(uval);
289 break;
290 case hwmon_temp_min_hyst:
291 ret = regmap_read(st->regmap, MAX31827_TL_HYST_REG,
292 &uval);
293 if (ret)
294 break;
295
296 *val = MAX31827_16_BIT_TO_M_DGR(uval);
297 break;
298 case hwmon_temp_min_alarm:
299 ret = regmap_read(st->regmap,
300 MAX31827_CONFIGURATION_REG, &uval);
301 if (ret)
302 break;
303
304 *val = FIELD_GET(MAX31827_CONFIGURATION_U_TEMP_STAT_MASK,
305 uval);
306 break;
307 default:
308 ret = -EOPNOTSUPP;
309 break;
310 }
311
312 break;
313
314 case hwmon_chip:
315 if (attr == hwmon_chip_update_interval) {
316 ret = regmap_read(st->regmap,
317 MAX31827_CONFIGURATION_REG, &uval);
318 if (ret)
319 break;
320
321 uval = FIELD_GET(MAX31827_CONFIGURATION_CNV_RATE_MASK,
322 uval);
323 *val = max31827_conversions[uval];
324 }
325 break;
326
327 default:
328 ret = -EOPNOTSUPP;
329 break;
330 }
331
332 return ret;
333}
334
335static int max31827_write(struct device *dev, enum hwmon_sensor_types type,
336 u32 attr, int channel, long val)
337{
338 struct max31827_state *st = dev_get_drvdata(dev);
339 int res = 1;
340 int ret;
341
342 switch (type) {
343 case hwmon_temp:
344 switch (attr) {
345 case hwmon_temp_enable:
346 if (val >> 1)
347 return -EINVAL;
348
349 mutex_lock(&st->lock);
350 /**
351 * The chip should not be enabled while a conversion is
352 * performed. Neither should the chip be enabled when
353 * the alarm values are changed.
354 */
355
356 st->enable = val;
357
358 ret = regmap_update_bits(st->regmap,
359 MAX31827_CONFIGURATION_REG,
360 MAX31827_CONFIGURATION_1SHOT_MASK |
361 MAX31827_CONFIGURATION_CNV_RATE_MASK,
362 MAX31827_DEVICE_ENABLE(val));
363
364 mutex_unlock(&st->lock);
365
366 return ret;
367
368 case hwmon_temp_max:
369 return write_alarm_val(st, MAX31827_TH_REG, val);
370
371 case hwmon_temp_max_hyst:
372 return write_alarm_val(st, MAX31827_TH_HYST_REG, val);
373
374 case hwmon_temp_min:
375 return write_alarm_val(st, MAX31827_TL_REG, val);
376
377 case hwmon_temp_min_hyst:
378 return write_alarm_val(st, MAX31827_TL_HYST_REG, val);
379
380 default:
381 return -EOPNOTSUPP;
382 }
383
384 case hwmon_chip:
385 if (attr == hwmon_chip_update_interval) {
386 if (!st->enable)
387 return -EINVAL;
388
389 /*
390 * Convert the desired conversion rate into register
391 * bits. res is already initialized with 1.
392 *
393 * This was inspired by lm73 driver.
394 */
395 while (res < ARRAY_SIZE(max31827_conversions) &&
396 val < max31827_conversions[res])
397 res++;
398
399 if (res == ARRAY_SIZE(max31827_conversions))
400 res = ARRAY_SIZE(max31827_conversions) - 1;
401
402 res = FIELD_PREP(MAX31827_CONFIGURATION_CNV_RATE_MASK,
403 res);
404
405 ret = regmap_update_bits(st->regmap,
406 MAX31827_CONFIGURATION_REG,
407 MAX31827_CONFIGURATION_CNV_RATE_MASK,
408 res);
409 if (ret)
410 return ret;
411
412 st->update_interval = val;
413 }
414 break;
415
416 default:
417 return -EOPNOTSUPP;
418 }
419
420 return 0;
421}
422
423static ssize_t temp1_resolution_show(struct device *dev,
424 struct device_attribute *devattr,
425 char *buf)
426{
427 struct max31827_state *st = dev_get_drvdata(dev);
428 unsigned int val;
429 int ret;
430
431 ret = regmap_read(st->regmap, MAX31827_CONFIGURATION_REG, &val);
432 if (ret)
433 return ret;
434
435 val = FIELD_GET(MAX31827_CONFIGURATION_RESOLUTION_MASK, val);
436
437 return scnprintf(buf, PAGE_SIZE, "%u\n", max31827_resolutions[val]);
438}
439
440static ssize_t temp1_resolution_store(struct device *dev,
441 struct device_attribute *devattr,
442 const char *buf, size_t count)
443{
444 struct max31827_state *st = dev_get_drvdata(dev);
445 unsigned int idx = 0;
446 unsigned int val;
447 int ret;
448
449 ret = kstrtouint(buf, 10, &val);
450 if (ret)
451 return ret;
452
453 /*
454 * Convert the desired resolution into register
455 * bits. idx is already initialized with 0.
456 *
457 * This was inspired by lm73 driver.
458 */
459 while (idx < ARRAY_SIZE(max31827_resolutions) &&
460 val < max31827_resolutions[idx])
461 idx++;
462
463 if (idx == ARRAY_SIZE(max31827_resolutions))
464 idx = ARRAY_SIZE(max31827_resolutions) - 1;
465
466 st->resolution = idx;
467
468 ret = shutdown_write(st, MAX31827_CONFIGURATION_REG,
469 MAX31827_CONFIGURATION_RESOLUTION_MASK,
470 FIELD_PREP(MAX31827_CONFIGURATION_RESOLUTION_MASK,
471 idx));
472
473 return ret ? ret : count;
474}
475
476static DEVICE_ATTR_RW(temp1_resolution);
477
478static struct attribute *max31827_attrs[] = {
479 &dev_attr_temp1_resolution.attr,
480 NULL
481};
482ATTRIBUTE_GROUPS(max31827);
483
484static const struct i2c_device_id max31827_i2c_ids[] = {
485 { "max31827", max31827 },
486 { "max31828", max31828 },
487 { "max31829", max31829 },
488 { }
489};
490MODULE_DEVICE_TABLE(i2c, max31827_i2c_ids);
491
492static int max31827_init_client(struct max31827_state *st,
493 struct device *dev)
494{
495 struct fwnode_handle *fwnode;
496 unsigned int res = 0;
497 u32 data, lsb_idx;
498 enum chips type;
499 bool prop;
500 int ret;
501
502 fwnode = dev_fwnode(dev);
503
504 st->enable = true;
505 res |= MAX31827_DEVICE_ENABLE(1);
506
507 res |= MAX31827_CONFIGURATION_RESOLUTION_MASK;
508
509 prop = fwnode_property_read_bool(fwnode, "adi,comp-int");
510 res |= FIELD_PREP(MAX31827_CONFIGURATION_COMP_INT_MASK, prop);
511
512 prop = fwnode_property_read_bool(fwnode, "adi,timeout-enable");
513 res |= FIELD_PREP(MAX31827_CONFIGURATION_TIMEOUT_MASK, !prop);
514
515 type = (enum chips)(uintptr_t)device_get_match_data(dev);
516
517 if (fwnode_property_present(fwnode, "adi,alarm-pol")) {
518 ret = fwnode_property_read_u32(fwnode, "adi,alarm-pol", &data);
519 if (ret)
520 return ret;
521
522 res |= FIELD_PREP(MAX31827_CONFIGURATION_ALRM_POL_MASK, !!data);
523 } else {
524 /*
525 * Set default value.
526 */
527 switch (type) {
528 case max31827:
529 case max31828:
530 res |= FIELD_PREP(MAX31827_CONFIGURATION_ALRM_POL_MASK,
531 MAX31827_ALRM_POL_LOW);
532 break;
533 case max31829:
534 res |= FIELD_PREP(MAX31827_CONFIGURATION_ALRM_POL_MASK,
535 MAX31827_ALRM_POL_HIGH);
536 break;
537 default:
538 return -EOPNOTSUPP;
539 }
540 }
541
542 if (fwnode_property_present(fwnode, "adi,fault-q")) {
543 ret = fwnode_property_read_u32(fwnode, "adi,fault-q", &data);
544 if (ret)
545 return ret;
546
547 /*
548 * Convert the desired fault queue into register bits.
549 */
550 if (data != 0)
551 lsb_idx = __ffs(data);
552
553 if (hweight32(data) != 1 || lsb_idx > 4) {
554 dev_err(dev, "Invalid data in adi,fault-q\n");
555 return -EINVAL;
556 }
557
558 res |= FIELD_PREP(MAX31827_CONFIGURATION_FLT_Q_MASK, lsb_idx);
559 } else {
560 /*
561 * Set default value.
562 */
563 switch (type) {
564 case max31827:
565 res |= FIELD_PREP(MAX31827_CONFIGURATION_FLT_Q_MASK,
566 MAX31827_FLT_Q_1);
567 break;
568 case max31828:
569 case max31829:
570 res |= FIELD_PREP(MAX31827_CONFIGURATION_FLT_Q_MASK,
571 MAX31827_FLT_Q_4);
572 break;
573 default:
574 return -EOPNOTSUPP;
575 }
576 }
577
578 return regmap_write(st->regmap, MAX31827_CONFIGURATION_REG, res);
579}
580
581static const struct hwmon_channel_info *max31827_info[] = {
582 HWMON_CHANNEL_INFO(temp, HWMON_T_ENABLE | HWMON_T_INPUT | HWMON_T_MIN |
583 HWMON_T_MIN_HYST | HWMON_T_MIN_ALARM |
584 HWMON_T_MAX | HWMON_T_MAX_HYST |
585 HWMON_T_MAX_ALARM),
586 HWMON_CHANNEL_INFO(chip, HWMON_C_UPDATE_INTERVAL),
587 NULL,
588};
589
590static const struct hwmon_ops max31827_hwmon_ops = {
591 .is_visible = max31827_is_visible,
592 .read = max31827_read,
593 .write = max31827_write,
594};
595
596static const struct hwmon_chip_info max31827_chip_info = {
597 .ops = &max31827_hwmon_ops,
598 .info = max31827_info,
599};
600
601static int max31827_probe(struct i2c_client *client)
602{
603 struct device *dev = &client->dev;
604 struct device *hwmon_dev;
605 struct max31827_state *st;
606 int err;
607
608 if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_WORD_DATA))
609 return -EOPNOTSUPP;
610
611 st = devm_kzalloc(dev, sizeof(*st), GFP_KERNEL);
612 if (!st)
613 return -ENOMEM;
614
615 mutex_init(&st->lock);
616
617 st->regmap = devm_regmap_init_i2c(client, &max31827_regmap);
618 if (IS_ERR(st->regmap))
619 return dev_err_probe(dev, PTR_ERR(st->regmap),
620 "Failed to allocate regmap.\n");
621
622 err = devm_regulator_get_enable(dev, "vref");
623 if (err)
624 return dev_err_probe(dev, err, "failed to enable regulator\n");
625
626 err = max31827_init_client(st, dev);
627 if (err)
628 return err;
629
630 hwmon_dev = devm_hwmon_device_register_with_info(dev, client->name, st,
631 &max31827_chip_info,
632 max31827_groups);
633
634 return PTR_ERR_OR_ZERO(hwmon_dev);
635}
636
637static const struct of_device_id max31827_of_match[] = {
638 {
639 .compatible = "adi,max31827",
640 .data = (void *)max31827
641 },
642 {
643 .compatible = "adi,max31828",
644 .data = (void *)max31828
645 },
646 {
647 .compatible = "adi,max31829",
648 .data = (void *)max31829
649 },
650 { }
651};
652MODULE_DEVICE_TABLE(of, max31827_of_match);
653
654static struct i2c_driver max31827_driver = {
655 .class = I2C_CLASS_HWMON,
656 .driver = {
657 .name = "max31827",
658 .of_match_table = max31827_of_match,
659 },
660 .probe = max31827_probe,
661 .id_table = max31827_i2c_ids,
662};
663module_i2c_driver(max31827_driver);
664
665MODULE_AUTHOR("Daniel Matyas <daniel.matyas@analog.com>");
666MODULE_DESCRIPTION("Maxim MAX31827 low-power temperature switch driver");
667MODULE_LICENSE("GPL");