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
|
/*
* mlx90614.c - Support for Melexis MLX90614 contactless IR temperature sensor
*
* Copyright (c) 2014 Peter Meerwald <pmeerw@pmeerw.net>
* Copyright (c) 2015 Essensium NV
* Copyright (c) 2015 Melexis
*
* This file is subject to the terms and conditions of version 2 of
* the GNU General Public License. See the file COPYING in the main
* directory of this archive for more details.
*
* Driver for the Melexis MLX90614 I2C 16-bit IR thermopile sensor
*
* (7-bit I2C slave address 0x5a, 100KHz bus speed only!)
*
* To wake up from sleep mode, the SDA line must be held low while SCL is high
* for at least 33ms. This is achieved with an extra GPIO that can be connected
* directly to the SDA line. In normal operation, the GPIO is set as input and
* will not interfere in I2C communication. While the GPIO is driven low, the
* i2c adapter is locked since it cannot be used by other clients. The SCL line
* always has a pull-up so we do not need an extra GPIO to drive it high. If
* the "wakeup" GPIO is not given, power management will be disabled.
*
*/
#include <linux/err.h>
#include <linux/i2c.h>
#include <linux/module.h>
#include <linux/delay.h>
#include <linux/jiffies.h>
#include <linux/gpio/consumer.h>
#include <linux/pm_runtime.h>
#include <linux/iio/iio.h>
#include <linux/iio/sysfs.h>
#define MLX90614_OP_RAM 0x00
#define MLX90614_OP_EEPROM 0x20
#define MLX90614_OP_SLEEP 0xff
/* RAM offsets with 16-bit data, MSB first */
#define MLX90614_RAW1 (MLX90614_OP_RAM | 0x04) /* raw data IR channel 1 */
#define MLX90614_RAW2 (MLX90614_OP_RAM | 0x05) /* raw data IR channel 2 */
#define MLX90614_TA (MLX90614_OP_RAM | 0x06) /* ambient temperature */
#define MLX90614_TOBJ1 (MLX90614_OP_RAM | 0x07) /* object 1 temperature */
#define MLX90614_TOBJ2 (MLX90614_OP_RAM | 0x08) /* object 2 temperature */
/* EEPROM offsets with 16-bit data, MSB first */
#define MLX90614_EMISSIVITY (MLX90614_OP_EEPROM | 0x04) /* emissivity correction coefficient */
#define MLX90614_CONFIG (MLX90614_OP_EEPROM | 0x05) /* configuration register */
/* Control bits in configuration register */
#define MLX90614_CONFIG_IIR_SHIFT 0 /* IIR coefficient */
#define MLX90614_CONFIG_IIR_MASK (0x7 << MLX90614_CONFIG_IIR_SHIFT)
#define MLX90614_CONFIG_DUAL_SHIFT 6 /* single (0) or dual (1) IR sensor */
#define MLX90614_CONFIG_DUAL_MASK (1 << MLX90614_CONFIG_DUAL_SHIFT)
#define MLX90614_CONFIG_FIR_SHIFT 8 /* FIR coefficient */
#define MLX90614_CONFIG_FIR_MASK (0x7 << MLX90614_CONFIG_FIR_SHIFT)
#define MLX90614_CONFIG_GAIN_SHIFT 11 /* gain */
#define MLX90614_CONFIG_GAIN_MASK (0x7 << MLX90614_CONFIG_GAIN_SHIFT)
/* Timings (in ms) */
#define MLX90614_TIMING_EEPROM 20 /* time for EEPROM write/erase to complete */
#define MLX90614_TIMING_WAKEUP 34 /* time to hold SDA low for wake-up */
#define MLX90614_TIMING_STARTUP 250 /* time before first data after wake-up */
#define MLX90614_AUTOSLEEP_DELAY 5000 /* default autosleep delay */
/* Magic constants */
#define MLX90614_CONST_OFFSET_DEC -13657 /* decimal part of the Kelvin offset */
#define MLX90614_CONST_OFFSET_REM 500000 /* remainder of offset (273.15*50) */
#define MLX90614_CONST_SCALE 20 /* Scale in milliKelvin (0.02 * 1000) */
#define MLX90614_CONST_RAW_EMISSIVITY_MAX 65535 /* max value for emissivity */
#define MLX90614_CONST_EMISSIVITY_RESOLUTION 15259 /* 1/65535 ~ 0.000015259 */
#define MLX90614_CONST_FIR 0x7 /* Fixed value for FIR part of low pass filter */
struct mlx90614_data {
struct i2c_client *client;
struct mutex lock; /* for EEPROM access only */
struct gpio_desc *wakeup_gpio; /* NULL to disable sleep/wake-up */
unsigned long ready_timestamp; /* in jiffies */
};
/* Bandwidth values for IIR filtering */
static const int mlx90614_iir_values[] = {77, 31, 20, 15, 723, 153, 110, 86};
static IIO_CONST_ATTR(in_temp_object_filter_low_pass_3db_frequency_available,
"0.15 0.20 0.31 0.77 0.86 1.10 1.53 7.23");
static struct attribute *mlx90614_attributes[] = {
&iio_const_attr_in_temp_object_filter_low_pass_3db_frequency_available.dev_attr.attr,
NULL,
};
static const struct attribute_group mlx90614_attr_group = {
.attrs = mlx90614_attributes,
};
/*
* Erase an address and write word.
* The mutex must be locked before calling.
*/
static s32 mlx90614_write_word(const struct i2c_client *client, u8 command,
u16 value)
{
/*
* Note: The mlx90614 requires a PEC on writing but does not send us a
* valid PEC on reading. Hence, we cannot set I2C_CLIENT_PEC in
* i2c_client.flags. As a workaround, we use i2c_smbus_xfer here.
*/
union i2c_smbus_data data;
s32 ret;
dev_dbg(&client->dev, "Writing 0x%x to address 0x%x", value, command);
data.word = 0x0000; /* erase command */
ret = i2c_smbus_xfer(client->adapter, client->addr,
client->flags | I2C_CLIENT_PEC,
I2C_SMBUS_WRITE, command,
I2C_SMBUS_WORD_DATA, &data);
if (ret < 0)
return ret;
msleep(MLX90614_TIMING_EEPROM);
data.word = value; /* actual write */
ret = i2c_smbus_xfer(client->adapter, client->addr,
client->flags | I2C_CLIENT_PEC,
I2C_SMBUS_WRITE, command,
I2C_SMBUS_WORD_DATA, &data);
msleep(MLX90614_TIMING_EEPROM);
return ret;
}
/*
* Find the IIR value inside mlx90614_iir_values array and return its position
* which is equivalent to the bit value in sensor register
*/
static inline s32 mlx90614_iir_search(const struct i2c_client *client,
int value)
{
int i;
s32 ret;
for (i = 0; i < ARRAY_SIZE(mlx90614_iir_values); ++i) {
if (value == mlx90614_iir_values[i])
break;
}
if (i == ARRAY_SIZE(mlx90614_iir_values))
return -EINVAL;
/*
* CONFIG register values must not be changed so
* we must read them before we actually write
* changes
*/
ret = i2c_smbus_read_word_data(client, MLX90614_CONFIG);
if (ret < 0)
return ret;
ret &= ~MLX90614_CONFIG_FIR_MASK;
ret |= MLX90614_CONST_FIR << MLX90614_CONFIG_FIR_SHIFT;
ret &= ~MLX90614_CONFIG_IIR_MASK;
ret |= i << MLX90614_CONFIG_IIR_SHIFT;
/* Write changed values */
ret = mlx90614_write_word(client, MLX90614_CONFIG, ret);
return ret;
}
#ifdef CONFIG_PM
/*
* If @startup is true, make sure MLX90614_TIMING_STARTUP ms have elapsed since
* the last wake-up. This is normally only needed to get a valid temperature
* reading. EEPROM access does not need such delay.
* Return 0 on success, <0 on error.
*/
static int mlx90614_power_get(struct mlx90614_data *data, bool startup)
{
unsigned long now;
if (!data->wakeup_gpio)
return 0;
pm_runtime_get_sync(&data->client->dev);
if (startup) {
now = jiffies;
if (time_before(now, data->ready_timestamp) &&
msleep_interruptible(jiffies_to_msecs(
data->ready_timestamp - now)) != 0) {
pm_runtime_put_autosuspend(&data->client->dev);
return -EINTR;
}
}
return 0;
}
static void mlx90614_power_put(struct mlx90614_data *data)
{
if (!data->wakeup_gpio)
return;
pm_runtime_mark_last_busy(&data->client->dev);
pm_runtime_put_autosuspend(&data->client->dev);
}
#else
static inline int mlx90614_power_get(struct mlx90614_data *data, bool startup)
{
return 0;
}
static inline void mlx90614_power_put(struct mlx90614_data *data)
{
}
#endif
static int mlx90614_read_raw(struct iio_dev *indio_dev,
struct iio_chan_spec const *channel, int *val,
int *val2, long mask)
{
struct mlx90614_data *data = iio_priv(indio_dev);
u8 cmd;
s32 ret;
switch (mask) {
case IIO_CHAN_INFO_RAW: /* 0.02K / LSB */
switch (channel->channel2) {
case IIO_MOD_TEMP_AMBIENT:
cmd = MLX90614_TA;
break;
case IIO_MOD_TEMP_OBJECT:
switch (channel->channel) {
case 0:
cmd = MLX90614_TOBJ1;
break;
case 1:
cmd = MLX90614_TOBJ2;
break;
default:
return -EINVAL;
}
break;
default:
return -EINVAL;
}
ret = mlx90614_power_get(data, true);
if (ret < 0)
return ret;
ret = i2c_smbus_read_word_data(data->client, cmd);
mlx90614_power_put(data);
if (ret < 0)
return ret;
/* MSB is an error flag */
if (ret & 0x8000)
return -EIO;
*val = ret;
return IIO_VAL_INT<
|