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9#include <linux/ctype.h>
10#include <linux/module.h>
11#include <linux/init.h>
12#include <linux/err.h>
13#include <linux/spi/spi.h>
14#include <linux/iio/iio.h>
15#include <linux/iio/sysfs.h>
16#include <linux/util_macros.h>
17#include <asm/unaligned.h>
18#include <dt-bindings/iio/temperature/thermocouple.h>
19
20
21
22
23#define MAX31856_RD_WR_BIT BIT(7)
24
25#define MAX31856_CR0_AUTOCONVERT BIT(7)
26#define MAX31856_CR0_1SHOT BIT(6)
27#define MAX31856_CR0_OCFAULT BIT(4)
28#define MAX31856_CR0_OCFAULT_MASK GENMASK(5, 4)
29#define MAX31856_CR0_FILTER_50HZ BIT(0)
30#define MAX31856_AVERAGING_MASK GENMASK(6, 4)
31#define MAX31856_AVERAGING_SHIFT 4
32#define MAX31856_TC_TYPE_MASK GENMASK(3, 0)
33#define MAX31856_FAULT_OVUV BIT(1)
34#define MAX31856_FAULT_OPEN BIT(0)
35
36
37#define MAX31856_CR0_REG 0x00
38#define MAX31856_CR1_REG 0x01
39#define MAX31856_MASK_REG 0x02
40#define MAX31856_CJHF_REG 0x03
41#define MAX31856_CJLF_REG 0x04
42#define MAX31856_LTHFTH_REG 0x05
43#define MAX31856_LTHFTL_REG 0x06
44#define MAX31856_LTLFTH_REG 0x07
45#define MAX31856_LTLFTL_REG 0x08
46#define MAX31856_CJTO_REG 0x09
47#define MAX31856_CJTH_REG 0x0A
48#define MAX31856_CJTL_REG 0x0B
49#define MAX31856_LTCBH_REG 0x0C
50#define MAX31856_LTCBM_REG 0x0D
51#define MAX31856_LTCBL_REG 0x0E
52#define MAX31856_SR_REG 0x0F
53
54static const struct iio_chan_spec max31856_channels[] = {
55 {
56 .type = IIO_TEMP,
57 .info_mask_separate =
58 BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE) |
59 BIT(IIO_CHAN_INFO_THERMOCOUPLE_TYPE),
60 .info_mask_shared_by_type =
61 BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO)
62 },
63 {
64 .type = IIO_TEMP,
65 .channel2 = IIO_MOD_TEMP_AMBIENT,
66 .modified = 1,
67 .info_mask_separate =
68 BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
69 .info_mask_shared_by_type =
70 BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO)
71 },
72};
73
74struct max31856_data {
75 struct spi_device *spi;
76 u32 thermocouple_type;
77 bool filter_50hz;
78 int averaging;
79};
80
81static const char max31856_tc_types[] = {
82 'B', 'E', 'J', 'K', 'N', 'R', 'S', 'T'
83};
84
85static int max31856_read(struct max31856_data *data, u8 reg,
86 u8 val[], unsigned int read_size)
87{
88 return spi_write_then_read(data->spi, ®, 1, val, read_size);
89}
90
91static int max31856_write(struct max31856_data *data, u8 reg,
92 unsigned int val)
93{
94 u8 buf[2];
95
96 buf[0] = reg | (MAX31856_RD_WR_BIT);
97 buf[1] = val;
98
99 return spi_write(data->spi, buf, 2);
100}
101
102static int max31856_init(struct max31856_data *data)
103{
104 int ret;
105 u8 reg_cr0_val, reg_cr1_val;
106
107
108
109
110
111 ret = max31856_read(data, MAX31856_CR0_REG, ®_cr0_val, 1);
112 if (ret)
113 return ret;
114
115 reg_cr0_val &= ~MAX31856_CR0_AUTOCONVERT;
116 ret = max31856_write(data, MAX31856_CR0_REG, reg_cr0_val);
117 if (ret)
118 return ret;
119
120
121 ret = max31856_read(data, MAX31856_CR1_REG, ®_cr1_val, 1);
122 if (ret)
123 return ret;
124
125 reg_cr1_val &= ~MAX31856_TC_TYPE_MASK;
126 reg_cr1_val |= data->thermocouple_type;
127
128 reg_cr1_val &= ~MAX31856_AVERAGING_MASK;
129 reg_cr1_val |= data->averaging << MAX31856_AVERAGING_SHIFT;
130
131 ret = max31856_write(data, MAX31856_CR1_REG, reg_cr1_val);
132 if (ret)
133 return ret;
134
135
136
137
138
139
140 reg_cr0_val &= ~MAX31856_CR0_OCFAULT_MASK;
141 reg_cr0_val |= MAX31856_CR0_OCFAULT;
142
143
144 reg_cr0_val &= ~MAX31856_CR0_1SHOT;
145 reg_cr0_val |= MAX31856_CR0_AUTOCONVERT;
146
147 if (data->filter_50hz)
148 reg_cr0_val |= MAX31856_CR0_FILTER_50HZ;
149 else
150 reg_cr0_val &= ~MAX31856_CR0_FILTER_50HZ;
151
152 return max31856_write(data, MAX31856_CR0_REG, reg_cr0_val);
153}
154
155static int max31856_thermocouple_read(struct max31856_data *data,
156 struct iio_chan_spec const *chan,
157 int *val)
158{
159 int ret, offset_cjto;
160 u8 reg_val[3];
161
162 switch (chan->channel2) {
163 case IIO_NO_MOD:
164
165
166
167
168 ret = max31856_read(data, MAX31856_LTCBH_REG, reg_val, 3);
169 if (ret)
170 return ret;
171
172 *val = get_unaligned_be24(®_val[0]) >> 5;
173
174 if (reg_val[0] & 0x80)
175 *val -= 0x80000;
176 break;
177
178 case IIO_MOD_TEMP_AMBIENT:
179
180
181
182
183 ret = max31856_read(data, MAX31856_CJTO_REG, reg_val, 3);
184 if (ret)
185 return ret;
186
187 offset_cjto = reg_val[0];
188
189 *val = get_unaligned_be16(®_val[1]) >> 2;
190
191 *val += offset_cjto;
192
193 if (reg_val[1] & 0x80)
194 *val -= 0x4000;
195 break;
196
197 default:
198 return -EINVAL;
199 }
200
201 ret = max31856_read(data, MAX31856_SR_REG, reg_val, 1);
202 if (ret)
203 return ret;
204
205 if (reg_val[0] & (MAX31856_FAULT_OVUV | MAX31856_FAULT_OPEN))
206 return -EIO;
207
208 return ret;
209}
210
211static int max31856_read_raw(struct iio_dev *indio_dev,
212 struct iio_chan_spec const *chan,
213 int *val, int *val2, long mask)
214{
215 struct max31856_data *data = iio_priv(indio_dev);
216 int ret;
217
218 switch (mask) {
219 case IIO_CHAN_INFO_RAW:
220 ret = max31856_thermocouple_read(data, chan, val);
221 if (ret)
222 return ret;
223 return IIO_VAL_INT;
224 case IIO_CHAN_INFO_SCALE:
225 switch (chan->channel2) {
226 case IIO_MOD_TEMP_AMBIENT:
227
228 *val = 15;
229 *val2 = 625000;
230 ret = IIO_VAL_INT_PLUS_MICRO;
231 break;
232 default:
233
234 *val = 7;
235 *val2 = 812500;
236 return IIO_VAL_INT_PLUS_MICRO;
237 }
238 break;
239 case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
240 *val = 1 << data->averaging;
241 return IIO_VAL_INT;
242 case IIO_CHAN_INFO_THERMOCOUPLE_TYPE:
243 *val = max31856_tc_types[data->thermocouple_type];
244 return IIO_VAL_CHAR;
245 default:
246 ret = -EINVAL;
247 break;
248 }
249
250 return ret;
251}
252
253static int max31856_write_raw_get_fmt(struct iio_dev *indio_dev,
254 struct iio_chan_spec const *chan,
255 long mask)
256{
257 switch (mask) {
258 case IIO_CHAN_INFO_THERMOCOUPLE_TYPE:
259 return IIO_VAL_CHAR;
260 default:
261 return IIO_VAL_INT;
262 }
263}
264
265static int max31856_write_raw(struct iio_dev *indio_dev,
266 struct iio_chan_spec const *chan,
267 int val, int val2, long mask)
268{
269 struct max31856_data *data = iio_priv(indio_dev);
270 int msb;
271
272 switch (mask) {
273 case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
274 if (val > 16 || val < 1)
275 return -EINVAL;
276 msb = fls(val) - 1;
277
278 if (BIT(msb) < val)
279 msb++;
280
281 data->averaging = msb;
282 max31856_init(data);
283 break;
284 case IIO_CHAN_INFO_THERMOCOUPLE_TYPE:
285 {
286 int tc_type = -1;
287 int i;
288
289 for (i = 0; i < ARRAY_SIZE(max31856_tc_types); i++) {
290 if (max31856_tc_types[i] == toupper(val)) {
291 tc_type = i;
292 break;
293 }
294 }
295 if (tc_type < 0)
296 return -EINVAL;
297
298 data->thermocouple_type = tc_type;
299 max31856_init(data);
300 break;
301 }
302 default:
303 return -EINVAL;
304 }
305
306 return 0;
307}
308
309static ssize_t show_fault(struct device *dev, u8 faultbit, char *buf)
310{
311 struct iio_dev *indio_dev = dev_to_iio_dev(dev);
312 struct max31856_data *data = iio_priv(indio_dev);
313 u8 reg_val;
314 int ret;
315 bool fault;
316
317 ret = max31856_read(data, MAX31856_SR_REG, ®_val, 1);
318 if (ret)
319 return ret;
320
321 fault = reg_val & faultbit;
322
323 return sprintf(buf, "%d\n", fault);
324}
325
326static ssize_t show_fault_ovuv(struct device *dev,
327 struct device_attribute *attr,
328 char *buf)
329{
330 return show_fault(dev, MAX31856_FAULT_OVUV, buf);
331}
332
333static ssize_t show_fault_oc(struct device *dev,
334 struct device_attribute *attr,
335 char *buf)
336{
337 return show_fault(dev, MAX31856_FAULT_OPEN, buf);
338}
339
340static ssize_t show_filter(struct device *dev,
341 struct device_attribute *attr,
342 char *buf)
343{
344 struct iio_dev *indio_dev = dev_to_iio_dev(dev);
345 struct max31856_data *data = iio_priv(indio_dev);
346
347 return sprintf(buf, "%d\n", data->filter_50hz ? 50 : 60);
348}
349
350static ssize_t set_filter(struct device *dev,
351 struct device_attribute *attr,
352 const char *buf,
353 size_t len)
354{
355 struct iio_dev *indio_dev = dev_to_iio_dev(dev);
356 struct max31856_data *data = iio_priv(indio_dev);
357 unsigned int freq;
358 int ret;
359
360 ret = kstrtouint(buf, 10, &freq);
361 if (ret)
362 return ret;
363
364 switch (freq) {
365 case 50:
366 data->filter_50hz = true;
367 break;
368 case 60:
369 data->filter_50hz = false;
370 break;
371 default:
372 return -EINVAL;
373 }
374
375 max31856_init(data);
376 return len;
377}
378
379static IIO_DEVICE_ATTR(fault_ovuv, 0444, show_fault_ovuv, NULL, 0);
380static IIO_DEVICE_ATTR(fault_oc, 0444, show_fault_oc, NULL, 0);
381static IIO_DEVICE_ATTR(in_temp_filter_notch_center_frequency, 0644,
382 show_filter, set_filter, 0);
383
384static struct attribute *max31856_attributes[] = {
385 &iio_dev_attr_fault_ovuv.dev_attr.attr,
386 &iio_dev_attr_fault_oc.dev_attr.attr,
387 &iio_dev_attr_in_temp_filter_notch_center_frequency.dev_attr.attr,
388 NULL,
389};
390
391static const struct attribute_group max31856_group = {
392 .attrs = max31856_attributes,
393};
394
395static const struct iio_info max31856_info = {
396 .read_raw = max31856_read_raw,
397 .write_raw = max31856_write_raw,
398 .write_raw_get_fmt = max31856_write_raw_get_fmt,
399 .attrs = &max31856_group,
400};
401
402static int max31856_probe(struct spi_device *spi)
403{
404 const struct spi_device_id *id = spi_get_device_id(spi);
405 struct iio_dev *indio_dev;
406 struct max31856_data *data;
407 int ret;
408
409 indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*data));
410 if (!indio_dev)
411 return -ENOMEM;
412
413 data = iio_priv(indio_dev);
414 data->spi = spi;
415 data->filter_50hz = false;
416
417 spi_set_drvdata(spi, indio_dev);
418
419 indio_dev->info = &max31856_info;
420 indio_dev->name = id->name;
421 indio_dev->modes = INDIO_DIRECT_MODE;
422 indio_dev->channels = max31856_channels;
423 indio_dev->num_channels = ARRAY_SIZE(max31856_channels);
424
425 ret = of_property_read_u32(spi->dev.of_node, "thermocouple-type",
426 &data->thermocouple_type);
427
428 if (ret) {
429 dev_info(&spi->dev,
430 "Could not read thermocouple type DT property, configuring as a K-Type\n");
431 data->thermocouple_type = THERMOCOUPLE_TYPE_K;
432 }
433
434
435
436
437
438 switch (data->thermocouple_type) {
439 case THERMOCOUPLE_TYPE_B:
440 case THERMOCOUPLE_TYPE_E:
441 case THERMOCOUPLE_TYPE_J:
442 case THERMOCOUPLE_TYPE_K:
443 case THERMOCOUPLE_TYPE_N:
444 case THERMOCOUPLE_TYPE_R:
445 case THERMOCOUPLE_TYPE_S:
446 case THERMOCOUPLE_TYPE_T:
447 break;
448 default:
449 dev_err(&spi->dev,
450 "error: thermocouple-type %u not supported by max31856\n"
451 , data->thermocouple_type);
452 return -EINVAL;
453 }
454
455 ret = max31856_init(data);
456 if (ret) {
457 dev_err(&spi->dev, "error: Failed to configure max31856\n");
458 return ret;
459 }
460
461 return devm_iio_device_register(&spi->dev, indio_dev);
462}
463
464static const struct spi_device_id max31856_id[] = {
465 { "max31856", 0 },
466 { }
467};
468MODULE_DEVICE_TABLE(spi, max31856_id);
469
470static const struct of_device_id max31856_of_match[] = {
471 { .compatible = "maxim,max31856" },
472 { }
473};
474MODULE_DEVICE_TABLE(of, max31856_of_match);
475
476static struct spi_driver max31856_driver = {
477 .driver = {
478 .name = "max31856",
479 .of_match_table = max31856_of_match,
480 },
481 .probe = max31856_probe,
482 .id_table = max31856_id,
483};
484module_spi_driver(max31856_driver);
485
486MODULE_AUTHOR("Paresh Chaudhary <paresh.chaudhary@rockwellcollins.com>");
487MODULE_AUTHOR("Patrick Havelange <patrick.havelange@essensium.com>");
488MODULE_DESCRIPTION("Maxim MAX31856 thermocouple sensor driver");
489MODULE_LICENSE("GPL");
490
