1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * PNI RM3100 3-axis geomagnetic sensor driver core.
4 *
5 * Copyright (C) 2018 Song Qiang <songqiang1304521@gmail.com>
6 *
7 * User Manual available at
8 * <https://www.pnicorp.com/download/rm3100-user-manual/>
9 *
10 * TODO: event generation, pm.
11 */
12
13 #include <linux/delay.h>
14 #include <linux/interrupt.h>
15 #include <linux/module.h>
16 #include <linux/slab.h>
17
18 #include <linux/iio/buffer.h>
19 #include <linux/iio/iio.h>
20 #include <linux/iio/sysfs.h>
21 #include <linux/iio/trigger.h>
22 #include <linux/iio/triggered_buffer.h>
23 #include <linux/iio/trigger_consumer.h>
24
25 #include <asm/unaligned.h>
26
27 #include "rm3100.h"
28
29 /* Cycle Count Registers. */
30 #define RM3100_REG_CC_X 0x05
31 #define RM3100_REG_CC_Y 0x07
32 #define RM3100_REG_CC_Z 0x09
33
34 /* Poll Measurement Mode register. */
35 #define RM3100_REG_POLL 0x00
36 #define RM3100_POLL_X BIT(4)
37 #define RM3100_POLL_Y BIT(5)
38 #define RM3100_POLL_Z BIT(6)
39
40 /* Continuous Measurement Mode register. */
41 #define RM3100_REG_CMM 0x01
42 #define RM3100_CMM_START BIT(0)
43 #define RM3100_CMM_X BIT(4)
44 #define RM3100_CMM_Y BIT(5)
45 #define RM3100_CMM_Z BIT(6)
46
47 /* TiMe Rate Configuration register. */
48 #define RM3100_REG_TMRC 0x0B
49 #define RM3100_TMRC_OFFSET 0x92
50
51 /* Result Status register. */
52 #define RM3100_REG_STATUS 0x34
53 #define RM3100_STATUS_DRDY BIT(7)
54
55 /* Measurement result registers. */
56 #define RM3100_REG_MX2 0x24
57 #define RM3100_REG_MY2 0x27
58 #define RM3100_REG_MZ2 0x2a
59
60 #define RM3100_W_REG_START RM3100_REG_POLL
61 #define RM3100_W_REG_END RM3100_REG_TMRC
62 #define RM3100_R_REG_START RM3100_REG_POLL
63 #define RM3100_R_REG_END RM3100_REG_STATUS
64 #define RM3100_V_REG_START RM3100_REG_POLL
65 #define RM3100_V_REG_END RM3100_REG_STATUS
66
67 /*
68 * This is computed by hand, is the sum of channel storage bits and padding
69 * bits, which is 4+4+4+12=24 in here.
70 */
71 #define RM3100_SCAN_BYTES 24
72
73 #define RM3100_CMM_AXIS_SHIFT 4
74
75 struct rm3100_data {
76 struct regmap *regmap;
77 struct completion measuring_done;
78 bool use_interrupt;
79 int conversion_time;
80 int scale;
81 /* Ensure naturally aligned timestamp */
82 u8 buffer[RM3100_SCAN_BYTES] __aligned(8);
83 struct iio_trigger *drdy_trig;
84
85 /*
86 * This lock is for protecting the consistency of series of i2c
87 * operations, that is, to make sure a measurement process will
88 * not be interrupted by a set frequency operation, which should
89 * be taken where a series of i2c operation starts, released where
90 * the operation ends.
91 */
92 struct mutex lock;
93 };
94
95 static const struct regmap_range rm3100_readable_ranges[] = {
96 regmap_reg_range(RM3100_R_REG_START, RM3100_R_REG_END),
97 };
98
99 const struct regmap_access_table rm3100_readable_table = {
100 .yes_ranges = rm3100_readable_ranges,
101 .n_yes_ranges = ARRAY_SIZE(rm3100_readable_ranges),
102 };
103 EXPORT_SYMBOL_GPL(rm3100_readable_table);
104
105 static const struct regmap_range rm3100_writable_ranges[] = {
106 regmap_reg_range(RM3100_W_REG_START, RM3100_W_REG_END),
107 };
108
109 const struct regmap_access_table rm3100_writable_table = {
110 .yes_ranges = rm3100_writable_ranges,
111 .n_yes_ranges = ARRAY_SIZE(rm3100_writable_ranges),
112 };
113 EXPORT_SYMBOL_GPL(rm3100_writable_table);
114
115 static const struct regmap_range rm3100_volatile_ranges[] = {
116 regmap_reg_range(RM3100_V_REG_START, RM3100_V_REG_END),
117 };
118
119 const struct regmap_access_table rm3100_volatile_table = {
120 .yes_ranges = rm3100_volatile_ranges,
121 .n_yes_ranges = ARRAY_SIZE(rm3100_volatile_ranges),
122 };
123 EXPORT_SYMBOL_GPL(rm3100_volatile_table);
124
rm3100_thread_fn(int irq,void * d)125 static irqreturn_t rm3100_thread_fn(int irq, void *d)
126 {
127 struct iio_dev *indio_dev = d;
128 struct rm3100_data *data = iio_priv(indio_dev);
129
130 /*
131 * Write operation to any register or read operation
132 * to first byte of results will clear the interrupt.
133 */
134 regmap_write(data->regmap, RM3100_REG_POLL, 0);
135
136 return IRQ_HANDLED;
137 }
138
rm3100_irq_handler(int irq,void * d)139 static irqreturn_t rm3100_irq_handler(int irq, void *d)
140 {
141 struct iio_dev *indio_dev = d;
142 struct rm3100_data *data = iio_priv(indio_dev);
143
144 switch (indio_dev->currentmode) {
145 case INDIO_DIRECT_MODE:
146 complete(&data->measuring_done);
147 break;
148 case INDIO_BUFFER_TRIGGERED:
149 iio_trigger_poll(data->drdy_trig);
150 break;
151 default:
152 dev_err(indio_dev->dev.parent,
153 "device mode out of control, current mode: %d",
154 indio_dev->currentmode);
155 }
156
157 return IRQ_WAKE_THREAD;
158 }
159
rm3100_wait_measurement(struct rm3100_data * data)160 static int rm3100_wait_measurement(struct rm3100_data *data)
161 {
162 struct regmap *regmap = data->regmap;
163 unsigned int val;
164 int tries = 20;
165 int ret;
166
167 /*
168 * A read cycle of 400kbits i2c bus is about 20us, plus the time
169 * used for scheduling, a read cycle of fast mode of this device
170 * can reach 1.7ms, it may be possible for data to arrive just
171 * after we check the RM3100_REG_STATUS. In this case, irq_handler is
172 * called before measuring_done is reinitialized, it will wait
173 * forever for data that has already been ready.
174 * Reinitialize measuring_done before looking up makes sure we
175 * will always capture interrupt no matter when it happens.
176 */
177 if (data->use_interrupt)
178 reinit_completion(&data->measuring_done);
179
180 ret = regmap_read(regmap, RM3100_REG_STATUS, &val);
181 if (ret < 0)
182 return ret;
183
184 if ((val & RM3100_STATUS_DRDY) != RM3100_STATUS_DRDY) {
185 if (data->use_interrupt) {
186 ret = wait_for_completion_timeout(&data->measuring_done,
187 msecs_to_jiffies(data->conversion_time));
188 if (!ret)
189 return -ETIMEDOUT;
190 } else {
191 do {
192 usleep_range(1000, 5000);
193
194 ret = regmap_read(regmap, RM3100_REG_STATUS,
195 &val);
196 if (ret < 0)
197 return ret;
198
199 if (val & RM3100_STATUS_DRDY)
200 break;
201 } while (--tries);
202 if (!tries)
203 return -ETIMEDOUT;
204 }
205 }
206 return 0;
207 }
208
rm3100_read_mag(struct rm3100_data * data,int idx,int * val)209 static int rm3100_read_mag(struct rm3100_data *data, int idx, int *val)
210 {
211 struct regmap *regmap = data->regmap;
212 u8 buffer[3];
213 int ret;
214
215 mutex_lock(&data->lock);
216 ret = regmap_write(regmap, RM3100_REG_POLL, BIT(4 + idx));
217 if (ret < 0)
218 goto unlock_return;
219
220 ret = rm3100_wait_measurement(data);
221 if (ret < 0)
222 goto unlock_return;
223
224 ret = regmap_bulk_read(regmap, RM3100_REG_MX2 + 3 * idx, buffer, 3);
225 if (ret < 0)
226 goto unlock_return;
227 mutex_unlock(&data->lock);
228
229 *val = sign_extend32(get_unaligned_be24(&buffer[0]), 23);
230
231 return IIO_VAL_INT;
232
233 unlock_return:
234 mutex_unlock(&data->lock);
235 return ret;
236 }
237
238 #define RM3100_CHANNEL(axis, idx) \
239 { \
240 .type = IIO_MAGN, \
241 .modified = 1, \
242 .channel2 = IIO_MOD_##axis, \
243 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
244 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) | \
245 BIT(IIO_CHAN_INFO_SAMP_FREQ), \
246 .scan_index = idx, \
247 .scan_type = { \
248 .sign = 's', \
249 .realbits = 24, \
250 .storagebits = 32, \
251 .shift = 8, \
252 .endianness = IIO_BE, \
253 }, \
254 }
255
256 static const struct iio_chan_spec rm3100_channels[] = {
257 RM3100_CHANNEL(X, 0),
258 RM3100_CHANNEL(Y, 1),
259 RM3100_CHANNEL(Z, 2),
260 IIO_CHAN_SOFT_TIMESTAMP(3),
261 };
262
263 static IIO_CONST_ATTR_SAMP_FREQ_AVAIL(
264 "600 300 150 75 37 18 9 4.5 2.3 1.2 0.6 0.3 0.015 0.075"
265 );
266
267 static struct attribute *rm3100_attributes[] = {
268 &iio_const_attr_sampling_frequency_available.dev_attr.attr,
269 NULL,
270 };
271
272 static const struct attribute_group rm3100_attribute_group = {
273 .attrs = rm3100_attributes,
274 };
275
276 #define RM3100_SAMP_NUM 14
277
278 /*
279 * Frequency : rm3100_samp_rates[][0].rm3100_samp_rates[][1]Hz.
280 * Time between reading: rm3100_sam_rates[][2]ms.
281 * The first one is actually 1.7ms.
282 */
283 static const int rm3100_samp_rates[RM3100_SAMP_NUM][3] = {
284 {600, 0, 2}, {300, 0, 3}, {150, 0, 7}, {75, 0, 13}, {37, 0, 27},
285 {18, 0, 55}, {9, 0, 110}, {4, 500000, 220}, {2, 300000, 440},
286 {1, 200000, 800}, {0, 600000, 1600}, {0, 300000, 3300},
287 {0, 15000, 6700}, {0, 75000, 13000}
288 };
289
rm3100_get_samp_freq(struct rm3100_data * data,int * val,int * val2)290 static int rm3100_get_samp_freq(struct rm3100_data *data, int *val, int *val2)
291 {
292 unsigned int tmp;
293 int ret;
294
295 mutex_lock(&data->lock);
296 ret = regmap_read(data->regmap, RM3100_REG_TMRC, &tmp);
297 mutex_unlock(&data->lock);
298 if (ret < 0)
299 return ret;
300 *val = rm3100_samp_rates[tmp - RM3100_TMRC_OFFSET][0];
301 *val2 = rm3100_samp_rates[tmp - RM3100_TMRC_OFFSET][1];
302
303 return IIO_VAL_INT_PLUS_MICRO;
304 }
305
rm3100_set_cycle_count(struct rm3100_data * data,int val)306 static int rm3100_set_cycle_count(struct rm3100_data *data, int val)
307 {
308 int ret;
309 u8 i;
310
311 for (i = 0; i < 3; i++) {
312 ret = regmap_write(data->regmap, RM3100_REG_CC_X + 2 * i, val);
313 if (ret < 0)
314 return ret;
315 }
316
317 /*
318 * The scale of this sensor depends on the cycle count value, these
319 * three values are corresponding to the cycle count value 50, 100,
320 * 200. scale = output / gain * 10^4.
321 */
322 switch (val) {
323 case 50:
324 data->scale = 500;
325 break;
326 case 100:
327 data->scale = 263;
328 break;
329 /*
330 * case 200:
331 * This function will never be called by users' code, so here we
332 * assume that it will never get a wrong parameter.
333 */
334 default:
335 data->scale = 133;
336 }
337
338 return 0;
339 }
340
rm3100_set_samp_freq(struct iio_dev * indio_dev,int val,int val2)341 static int rm3100_set_samp_freq(struct iio_dev *indio_dev, int val, int val2)
342 {
343 struct rm3100_data *data = iio_priv(indio_dev);
344 struct regmap *regmap = data->regmap;
345 unsigned int cycle_count;
346 int ret;
347 int i;
348
349 mutex_lock(&data->lock);
350 /* All cycle count registers use the same value. */
351 ret = regmap_read(regmap, RM3100_REG_CC_X, &cycle_count);
352 if (ret < 0)
353 goto unlock_return;
354
355 for (i = 0; i < RM3100_SAMP_NUM; i++) {
356 if (val == rm3100_samp_rates[i][0] &&
357 val2 == rm3100_samp_rates[i][1])
358 break;
359 }
360 if (i == RM3100_SAMP_NUM) {
361 ret = -EINVAL;
362 goto unlock_return;
363 }
364
365 ret = regmap_write(regmap, RM3100_REG_TMRC, i + RM3100_TMRC_OFFSET);
366 if (ret < 0)
367 goto unlock_return;
368
369 /* Checking if cycle count registers need changing. */
370 if (val == 600 && cycle_count == 200) {
371 ret = rm3100_set_cycle_count(data, 100);
372 if (ret < 0)
373 goto unlock_return;
374 } else if (val != 600 && cycle_count == 100) {
375 ret = rm3100_set_cycle_count(data, 200);
376 if (ret < 0)
377 goto unlock_return;
378 }
379
380 if (indio_dev->currentmode == INDIO_BUFFER_TRIGGERED) {
381 /* Writing TMRC registers requires CMM reset. */
382 ret = regmap_write(regmap, RM3100_REG_CMM, 0);
383 if (ret < 0)
384 goto unlock_return;
385 ret = regmap_write(data->regmap, RM3100_REG_CMM,
386 (*indio_dev->active_scan_mask & 0x7) <<
387 RM3100_CMM_AXIS_SHIFT | RM3100_CMM_START);
388 if (ret < 0)
389 goto unlock_return;
390 }
391 mutex_unlock(&data->lock);
392
393 data->conversion_time = rm3100_samp_rates[i][2] * 2;
394 return 0;
395
396 unlock_return:
397 mutex_unlock(&data->lock);
398 return ret;
399 }
400
rm3100_read_raw(struct iio_dev * indio_dev,const struct iio_chan_spec * chan,int * val,int * val2,long mask)401 static int rm3100_read_raw(struct iio_dev *indio_dev,
402 const struct iio_chan_spec *chan,
403 int *val, int *val2, long mask)
404 {
405 struct rm3100_data *data = iio_priv(indio_dev);
406 int ret;
407
408 switch (mask) {
409 case IIO_CHAN_INFO_RAW:
410 ret = iio_device_claim_direct_mode(indio_dev);
411 if (ret < 0)
412 return ret;
413
414 ret = rm3100_read_mag(data, chan->scan_index, val);
415 iio_device_release_direct_mode(indio_dev);
416
417 return ret;
418 case IIO_CHAN_INFO_SCALE:
419 *val = 0;
420 *val2 = data->scale;
421
422 return IIO_VAL_INT_PLUS_MICRO;
423 case IIO_CHAN_INFO_SAMP_FREQ:
424 return rm3100_get_samp_freq(data, val, val2);
425 default:
426 return -EINVAL;
427 }
428 }
429
rm3100_write_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int val,int val2,long mask)430 static int rm3100_write_raw(struct iio_dev *indio_dev,
431 struct iio_chan_spec const *chan,
432 int val, int val2, long mask)
433 {
434 switch (mask) {
435 case IIO_CHAN_INFO_SAMP_FREQ:
436 return rm3100_set_samp_freq(indio_dev, val, val2);
437 default:
438 return -EINVAL;
439 }
440 }
441
442 static const struct iio_info rm3100_info = {
443 .attrs = &rm3100_attribute_group,
444 .read_raw = rm3100_read_raw,
445 .write_raw = rm3100_write_raw,
446 };
447
rm3100_buffer_preenable(struct iio_dev * indio_dev)448 static int rm3100_buffer_preenable(struct iio_dev *indio_dev)
449 {
450 struct rm3100_data *data = iio_priv(indio_dev);
451
452 /* Starting channels enabled. */
453 return regmap_write(data->regmap, RM3100_REG_CMM,
454 (*indio_dev->active_scan_mask & 0x7) << RM3100_CMM_AXIS_SHIFT |
455 RM3100_CMM_START);
456 }
457
rm3100_buffer_postdisable(struct iio_dev * indio_dev)458 static int rm3100_buffer_postdisable(struct iio_dev *indio_dev)
459 {
460 struct rm3100_data *data = iio_priv(indio_dev);
461
462 return regmap_write(data->regmap, RM3100_REG_CMM, 0);
463 }
464
465 static const struct iio_buffer_setup_ops rm3100_buffer_ops = {
466 .preenable = rm3100_buffer_preenable,
467 .postdisable = rm3100_buffer_postdisable,
468 };
469
rm3100_trigger_handler(int irq,void * p)470 static irqreturn_t rm3100_trigger_handler(int irq, void *p)
471 {
472 struct iio_poll_func *pf = p;
473 struct iio_dev *indio_dev = pf->indio_dev;
474 unsigned long scan_mask = *indio_dev->active_scan_mask;
475 unsigned int mask_len = indio_dev->masklength;
476 struct rm3100_data *data = iio_priv(indio_dev);
477 struct regmap *regmap = data->regmap;
478 int ret, i, bit;
479
480 mutex_lock(&data->lock);
481 switch (scan_mask) {
482 case BIT(0) | BIT(1) | BIT(2):
483 ret = regmap_bulk_read(regmap, RM3100_REG_MX2, data->buffer, 9);
484 mutex_unlock(&data->lock);
485 if (ret < 0)
486 goto done;
487 /* Convert XXXYYYZZZxxx to XXXxYYYxZZZx. x for paddings. */
488 for (i = 2; i > 0; i--)
489 memmove(data->buffer + i * 4, data->buffer + i * 3, 3);
490 break;
491 case BIT(0) | BIT(1):
492 ret = regmap_bulk_read(regmap, RM3100_REG_MX2, data->buffer, 6);
493 mutex_unlock(&data->lock);
494 if (ret < 0)
495 goto done;
496 memmove(data->buffer + 4, data->buffer + 3, 3);
497 break;
498 case BIT(1) | BIT(2):
499 ret = regmap_bulk_read(regmap, RM3100_REG_MY2, data->buffer, 6);
500 mutex_unlock(&data->lock);
501 if (ret < 0)
502 goto done;
503 memmove(data->buffer + 4, data->buffer + 3, 3);
504 break;
505 case BIT(0) | BIT(2):
506 ret = regmap_bulk_read(regmap, RM3100_REG_MX2, data->buffer, 9);
507 mutex_unlock(&data->lock);
508 if (ret < 0)
509 goto done;
510 memmove(data->buffer + 4, data->buffer + 6, 3);
511 break;
512 default:
513 for_each_set_bit(bit, &scan_mask, mask_len) {
514 ret = regmap_bulk_read(regmap, RM3100_REG_MX2 + 3 * bit,
515 data->buffer, 3);
516 if (ret < 0) {
517 mutex_unlock(&data->lock);
518 goto done;
519 }
520 }
521 mutex_unlock(&data->lock);
522 }
523 /*
524 * Always using the same buffer so that we wouldn't need to set the
525 * paddings to 0 in case of leaking any data.
526 */
527 iio_push_to_buffers_with_timestamp(indio_dev, data->buffer,
528 pf->timestamp);
529 done:
530 iio_trigger_notify_done(indio_dev->trig);
531
532 return IRQ_HANDLED;
533 }
534
rm3100_common_probe(struct device * dev,struct regmap * regmap,int irq)535 int rm3100_common_probe(struct device *dev, struct regmap *regmap, int irq)
536 {
537 struct iio_dev *indio_dev;
538 struct rm3100_data *data;
539 unsigned int tmp;
540 int ret;
541
542 indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
543 if (!indio_dev)
544 return -ENOMEM;
545
546 data = iio_priv(indio_dev);
547 data->regmap = regmap;
548
549 mutex_init(&data->lock);
550
551 indio_dev->name = "rm3100";
552 indio_dev->info = &rm3100_info;
553 indio_dev->channels = rm3100_channels;
554 indio_dev->num_channels = ARRAY_SIZE(rm3100_channels);
555 indio_dev->modes = INDIO_DIRECT_MODE | INDIO_BUFFER_TRIGGERED;
556 indio_dev->currentmode = INDIO_DIRECT_MODE;
557
558 if (!irq)
559 data->use_interrupt = false;
560 else {
561 data->use_interrupt = true;
562
563 init_completion(&data->measuring_done);
564 ret = devm_request_threaded_irq(dev,
565 irq,
566 rm3100_irq_handler,
567 rm3100_thread_fn,
568 IRQF_TRIGGER_HIGH |
569 IRQF_ONESHOT,
570 indio_dev->name,
571 indio_dev);
572 if (ret < 0) {
573 dev_err(dev, "request irq line failed.\n");
574 return ret;
575 }
576
577 data->drdy_trig = devm_iio_trigger_alloc(dev, "%s-drdy%d",
578 indio_dev->name,
579 iio_device_id(indio_dev));
580 if (!data->drdy_trig)
581 return -ENOMEM;
582
583 ret = devm_iio_trigger_register(dev, data->drdy_trig);
584 if (ret < 0)
585 return ret;
586 }
587
588 ret = devm_iio_triggered_buffer_setup(dev, indio_dev,
589 &iio_pollfunc_store_time,
590 rm3100_trigger_handler,
591 &rm3100_buffer_ops);
592 if (ret < 0)
593 return ret;
594
595 ret = regmap_read(regmap, RM3100_REG_TMRC, &tmp);
596 if (ret < 0)
597 return ret;
598 /* Initializing max wait time, which is double conversion time. */
599 data->conversion_time = rm3100_samp_rates[tmp - RM3100_TMRC_OFFSET][2]
600 * 2;
601
602 /* Cycle count values may not be what we want. */
603 if ((tmp - RM3100_TMRC_OFFSET) == 0)
604 rm3100_set_cycle_count(data, 100);
605 else
606 rm3100_set_cycle_count(data, 200);
607
608 return devm_iio_device_register(dev, indio_dev);
609 }
610 EXPORT_SYMBOL_GPL(rm3100_common_probe);
611
612 MODULE_AUTHOR("Song Qiang <songqiang1304521@gmail.com>");
613 MODULE_DESCRIPTION("PNI RM3100 3-axis magnetometer i2c driver");
614 MODULE_LICENSE("GPL v2");
615