1 /*
2  * mag3110.c - Support for Freescale MAG3110 magnetometer sensor
3  *
4  * Copyright (c) 2013 Peter Meerwald <pmeerw@pmeerw.net>
5  *
6  * This file is subject to the terms and conditions of version 2 of
7  * the GNU General Public License.  See the file COPYING in the main
8  * directory of this archive for more details.
9  *
10  * (7-bit I2C slave address 0x0e)
11  *
12  * TODO: irq, user offset, oversampling, continuous mode
13  */
14 
15 #include <linux/module.h>
16 #include <linux/i2c.h>
17 #include <linux/iio/iio.h>
18 #include <linux/iio/sysfs.h>
19 #include <linux/iio/trigger_consumer.h>
20 #include <linux/iio/buffer.h>
21 #include <linux/iio/triggered_buffer.h>
22 #include <linux/delay.h>
23 
24 #define MAG3110_STATUS 0x00
25 #define MAG3110_OUT_X 0x01 /* MSB first */
26 #define MAG3110_OUT_Y 0x03
27 #define MAG3110_OUT_Z 0x05
28 #define MAG3110_WHO_AM_I 0x07
29 #define MAG3110_SYSMOD 0x08
30 #define MAG3110_OFF_X 0x09 /* MSB first */
31 #define MAG3110_OFF_Y 0x0b
32 #define MAG3110_OFF_Z 0x0d
33 #define MAG3110_DIE_TEMP 0x0f
34 #define MAG3110_CTRL_REG1 0x10
35 #define MAG3110_CTRL_REG2 0x11
36 
37 #define MAG3110_STATUS_DRDY (BIT(2) | BIT(1) | BIT(0))
38 
39 #define MAG3110_CTRL_DR_MASK (BIT(7) | BIT(6) | BIT(5))
40 #define MAG3110_CTRL_DR_SHIFT 5
41 #define MAG3110_CTRL_DR_DEFAULT 0
42 
43 #define MAG3110_SYSMOD_MODE_MASK GENMASK(1, 0)
44 
45 #define MAG3110_CTRL_TM BIT(1) /* trigger single measurement */
46 #define MAG3110_CTRL_AC BIT(0) /* continuous measurements */
47 
48 #define MAG3110_CTRL_AUTO_MRST_EN BIT(7) /* magnetic auto-reset */
49 #define MAG3110_CTRL_RAW BIT(5) /* measurements not user-offset corrected */
50 
51 #define MAG3110_DEVICE_ID 0xc4
52 
53 /* Each client has this additional data */
54 struct mag3110_data {
55 	struct i2c_client *client;
56 	struct mutex lock;
57 	u8 ctrl_reg1;
58 	int sleep_val;
59 };
60 
61 static int mag3110_request(struct mag3110_data *data)
62 {
63 	int ret, tries = 150;
64 
65 	if ((data->ctrl_reg1 & MAG3110_CTRL_AC) == 0) {
66 		/* trigger measurement */
67 		ret = i2c_smbus_write_byte_data(data->client, MAG3110_CTRL_REG1,
68 			data->ctrl_reg1 | MAG3110_CTRL_TM);
69 		if (ret < 0)
70 			return ret;
71 	}
72 
73 	while (tries-- > 0) {
74 		ret = i2c_smbus_read_byte_data(data->client, MAG3110_STATUS);
75 		if (ret < 0)
76 			return ret;
77 		/* wait for data ready */
78 		if ((ret & MAG3110_STATUS_DRDY) == MAG3110_STATUS_DRDY)
79 			break;
80 
81 		if (data->sleep_val <= 20)
82 			usleep_range(data->sleep_val * 250, data->sleep_val * 500);
83 		else
84 			msleep(20);
85 	}
86 
87 	if (tries < 0) {
88 		dev_err(&data->client->dev, "data not ready\n");
89 		return -EIO;
90 	}
91 
92 	return 0;
93 }
94 
95 static int mag3110_read(struct mag3110_data *data, __be16 buf[3])
96 {
97 	int ret;
98 
99 	mutex_lock(&data->lock);
100 	ret = mag3110_request(data);
101 	if (ret < 0) {
102 		mutex_unlock(&data->lock);
103 		return ret;
104 	}
105 	ret = i2c_smbus_read_i2c_block_data(data->client,
106 		MAG3110_OUT_X, 3 * sizeof(__be16), (u8 *) buf);
107 	mutex_unlock(&data->lock);
108 
109 	return ret;
110 }
111 
112 static ssize_t mag3110_show_int_plus_micros(char *buf,
113 	const int (*vals)[2], int n)
114 {
115 	size_t len = 0;
116 
117 	while (n-- > 0)
118 		len += scnprintf(buf + len, PAGE_SIZE - len,
119 			"%d.%06d ", vals[n][0], vals[n][1]);
120 
121 	/* replace trailing space by newline */
122 	buf[len - 1] = '\n';
123 
124 	return len;
125 }
126 
127 static int mag3110_get_int_plus_micros_index(const int (*vals)[2], int n,
128 					int val, int val2)
129 {
130 	while (n-- > 0)
131 		if (val == vals[n][0] && val2 == vals[n][1])
132 			return n;
133 
134 	return -EINVAL;
135 }
136 
137 static const int mag3110_samp_freq[8][2] = {
138 	{80, 0}, {40, 0}, {20, 0}, {10, 0}, {5, 0}, {2, 500000},
139 	{1, 250000}, {0, 625000}
140 };
141 
142 static ssize_t mag3110_show_samp_freq_avail(struct device *dev,
143 				struct device_attribute *attr, char *buf)
144 {
145 	return mag3110_show_int_plus_micros(buf, mag3110_samp_freq, 8);
146 }
147 
148 static IIO_DEV_ATTR_SAMP_FREQ_AVAIL(mag3110_show_samp_freq_avail);
149 
150 static int mag3110_get_samp_freq_index(struct mag3110_data *data,
151 	int val, int val2)
152 {
153 	return mag3110_get_int_plus_micros_index(mag3110_samp_freq, 8, val,
154 		val2);
155 }
156 
157 static int mag3110_calculate_sleep(struct mag3110_data *data)
158 {
159 	int ret, i = data->ctrl_reg1 >> MAG3110_CTRL_DR_SHIFT;
160 
161 	if (mag3110_samp_freq[i][0] > 0)
162 		ret = 1000 / mag3110_samp_freq[i][0];
163 	else
164 		ret = 1000;
165 
166 	return ret == 0 ? 1 : ret;
167 }
168 
169 static int mag3110_standby(struct mag3110_data *data)
170 {
171 	return i2c_smbus_write_byte_data(data->client, MAG3110_CTRL_REG1,
172 		data->ctrl_reg1 & ~MAG3110_CTRL_AC);
173 }
174 
175 static int mag3110_wait_standby(struct mag3110_data *data)
176 {
177 	int ret, tries = 30;
178 
179 	/*
180 	 * Takes up to 1/ODR to come out of active mode into stby
181 	 * Longest expected period is 12.5seconds.
182 	 * We'll sleep for 500ms between checks
183 	 */
184 	while (tries-- > 0) {
185 		ret = i2c_smbus_read_byte_data(data->client, MAG3110_SYSMOD);
186 		if (ret < 0) {
187 			dev_err(&data->client->dev, "i2c error\n");
188 			return ret;
189 		}
190 		/* wait for standby */
191 		if ((ret & MAG3110_SYSMOD_MODE_MASK) == 0)
192 			break;
193 
194 		msleep_interruptible(500);
195 	}
196 
197 	if (tries < 0) {
198 		dev_err(&data->client->dev, "device not entering standby mode\n");
199 		return -EIO;
200 	}
201 
202 	return 0;
203 }
204 
205 static int mag3110_active(struct mag3110_data *data)
206 {
207 	return i2c_smbus_write_byte_data(data->client, MAG3110_CTRL_REG1,
208 					 data->ctrl_reg1);
209 }
210 
211 /* returns >0 if active, 0 if in standby and <0 on error */
212 static int mag3110_is_active(struct mag3110_data *data)
213 {
214 	int reg;
215 
216 	reg = i2c_smbus_read_byte_data(data->client, MAG3110_CTRL_REG1);
217 	if (reg < 0)
218 		return reg;
219 
220 	return reg & MAG3110_CTRL_AC;
221 }
222 
223 static int mag3110_change_config(struct mag3110_data *data, u8 reg, u8 val)
224 {
225 	int ret;
226 	int is_active;
227 
228 	mutex_lock(&data->lock);
229 
230 	is_active = mag3110_is_active(data);
231 	if (is_active < 0) {
232 		ret = is_active;
233 		goto fail;
234 	}
235 
236 	/* config can only be changed when in standby */
237 	if (is_active > 0) {
238 		ret = mag3110_standby(data);
239 		if (ret < 0)
240 			goto fail;
241 	}
242 
243 	/*
244 	 * After coming out of active we must wait for the part
245 	 * to transition to STBY. This can take up to 1 /ODR to occur
246 	 */
247 	ret = mag3110_wait_standby(data);
248 	if (ret < 0)
249 		goto fail;
250 
251 	ret = i2c_smbus_write_byte_data(data->client, reg, val);
252 	if (ret < 0)
253 		goto fail;
254 
255 	if (is_active > 0) {
256 		ret = mag3110_active(data);
257 		if (ret < 0)
258 			goto fail;
259 	}
260 
261 	ret = 0;
262 fail:
263 	mutex_unlock(&data->lock);
264 
265 	return ret;
266 }
267 
268 static int mag3110_read_raw(struct iio_dev *indio_dev,
269 			    struct iio_chan_spec const *chan,
270 			    int *val, int *val2, long mask)
271 {
272 	struct mag3110_data *data = iio_priv(indio_dev);
273 	__be16 buffer[3];
274 	int i, ret;
275 
276 	switch (mask) {
277 	case IIO_CHAN_INFO_RAW:
278 		ret = iio_device_claim_direct_mode(indio_dev);
279 		if (ret)
280 			return ret;
281 
282 		switch (chan->type) {
283 		case IIO_MAGN: /* in 0.1 uT / LSB */
284 			ret = mag3110_read(data, buffer);
285 			if (ret < 0)
286 				goto release;
287 			*val = sign_extend32(
288 				be16_to_cpu(buffer[chan->scan_index]), 15);
289 			ret = IIO_VAL_INT;
290 			break;
291 		case IIO_TEMP: /* in 1 C / LSB */
292 			mutex_lock(&data->lock);
293 			ret = mag3110_request(data);
294 			if (ret < 0) {
295 				mutex_unlock(&data->lock);
296 				goto release;
297 			}
298 			ret = i2c_smbus_read_byte_data(data->client,
299 				MAG3110_DIE_TEMP);
300 			mutex_unlock(&data->lock);
301 			if (ret < 0)
302 				goto release;
303 			*val = sign_extend32(ret, 7);
304 			ret = IIO_VAL_INT;
305 			break;
306 		default:
307 			ret = -EINVAL;
308 		}
309 release:
310 		iio_device_release_direct_mode(indio_dev);
311 		return ret;
312 
313 	case IIO_CHAN_INFO_SCALE:
314 		switch (chan->type) {
315 		case IIO_MAGN:
316 			*val = 0;
317 			*val2 = 1000;
318 			return IIO_VAL_INT_PLUS_MICRO;
319 		case IIO_TEMP:
320 			*val = 1000;
321 			return IIO_VAL_INT;
322 		default:
323 			return -EINVAL;
324 		}
325 	case IIO_CHAN_INFO_SAMP_FREQ:
326 		i = data->ctrl_reg1 >> MAG3110_CTRL_DR_SHIFT;
327 		*val = mag3110_samp_freq[i][0];
328 		*val2 = mag3110_samp_freq[i][1];
329 		return IIO_VAL_INT_PLUS_MICRO;
330 	case IIO_CHAN_INFO_CALIBBIAS:
331 		ret = i2c_smbus_read_word_swapped(data->client,
332 			MAG3110_OFF_X +	2 * chan->scan_index);
333 		if (ret < 0)
334 			return ret;
335 		*val = sign_extend32(ret >> 1, 14);
336 		return IIO_VAL_INT;
337 	}
338 	return -EINVAL;
339 }
340 
341 static int mag3110_write_raw(struct iio_dev *indio_dev,
342 			     struct iio_chan_spec const *chan,
343 			     int val, int val2, long mask)
344 {
345 	struct mag3110_data *data = iio_priv(indio_dev);
346 	int rate, ret;
347 
348 	ret = iio_device_claim_direct_mode(indio_dev);
349 	if (ret)
350 		return ret;
351 
352 	switch (mask) {
353 	case IIO_CHAN_INFO_SAMP_FREQ:
354 		rate = mag3110_get_samp_freq_index(data, val, val2);
355 		if (rate < 0) {
356 			ret = -EINVAL;
357 			break;
358 		}
359 		data->ctrl_reg1 &= 0xff & ~MAG3110_CTRL_DR_MASK
360 					& ~MAG3110_CTRL_AC;
361 		data->ctrl_reg1 |= rate << MAG3110_CTRL_DR_SHIFT;
362 		data->sleep_val = mag3110_calculate_sleep(data);
363 		if (data->sleep_val < 40)
364 			data->ctrl_reg1 |= MAG3110_CTRL_AC;
365 
366 		ret = mag3110_change_config(data, MAG3110_CTRL_REG1,
367 					    data->ctrl_reg1);
368 		break;
369 	case IIO_CHAN_INFO_CALIBBIAS:
370 		if (val < -10000 || val > 10000) {
371 			ret = -EINVAL;
372 			break;
373 		}
374 		ret = i2c_smbus_write_word_swapped(data->client,
375 			MAG3110_OFF_X + 2 * chan->scan_index, val << 1);
376 		break;
377 	default:
378 		ret = -EINVAL;
379 		break;
380 	}
381 	iio_device_release_direct_mode(indio_dev);
382 	return ret;
383 }
384 
385 static irqreturn_t mag3110_trigger_handler(int irq, void *p)
386 {
387 	struct iio_poll_func *pf = p;
388 	struct iio_dev *indio_dev = pf->indio_dev;
389 	struct mag3110_data *data = iio_priv(indio_dev);
390 	u8 buffer[16]; /* 3 16-bit channels + 1 byte temp + padding + ts */
391 	int ret;
392 
393 	ret = mag3110_read(data, (__be16 *) buffer);
394 	if (ret < 0)
395 		goto done;
396 
397 	if (test_bit(3, indio_dev->active_scan_mask)) {
398 		ret = i2c_smbus_read_byte_data(data->client,
399 			MAG3110_DIE_TEMP);
400 		if (ret < 0)
401 			goto done;
402 		buffer[6] = ret;
403 	}
404 
405 	iio_push_to_buffers_with_timestamp(indio_dev, buffer,
406 		iio_get_time_ns(indio_dev));
407 
408 done:
409 	iio_trigger_notify_done(indio_dev->trig);
410 	return IRQ_HANDLED;
411 }
412 
413 #define MAG3110_CHANNEL(axis, idx) { \
414 	.type = IIO_MAGN, \
415 	.modified = 1, \
416 	.channel2 = IIO_MOD_##axis, \
417 	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \
418 		BIT(IIO_CHAN_INFO_CALIBBIAS), \
419 	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SAMP_FREQ) | \
420 		BIT(IIO_CHAN_INFO_SCALE), \
421 	.scan_index = idx, \
422 	.scan_type = { \
423 		.sign = 's', \
424 		.realbits = 16, \
425 		.storagebits = 16, \
426 		.endianness = IIO_BE, \
427 	}, \
428 }
429 
430 static const struct iio_chan_spec mag3110_channels[] = {
431 	MAG3110_CHANNEL(X, 0),
432 	MAG3110_CHANNEL(Y, 1),
433 	MAG3110_CHANNEL(Z, 2),
434 	{
435 		.type = IIO_TEMP,
436 		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
437 			BIT(IIO_CHAN_INFO_SCALE),
438 		.scan_index = 3,
439 		.scan_type = {
440 			.sign = 's',
441 			.realbits = 8,
442 			.storagebits = 8,
443 			},
444 	},
445 	IIO_CHAN_SOFT_TIMESTAMP(4),
446 };
447 
448 static struct attribute *mag3110_attributes[] = {
449 	&iio_dev_attr_sampling_frequency_available.dev_attr.attr,
450 	NULL
451 };
452 
453 static const struct attribute_group mag3110_group = {
454 	.attrs = mag3110_attributes,
455 };
456 
457 static const struct iio_info mag3110_info = {
458 	.attrs = &mag3110_group,
459 	.read_raw = &mag3110_read_raw,
460 	.write_raw = &mag3110_write_raw,
461 };
462 
463 static const unsigned long mag3110_scan_masks[] = {0x7, 0xf, 0};
464 
465 static int mag3110_probe(struct i2c_client *client,
466 			 const struct i2c_device_id *id)
467 {
468 	struct mag3110_data *data;
469 	struct iio_dev *indio_dev;
470 	int ret;
471 
472 	ret = i2c_smbus_read_byte_data(client, MAG3110_WHO_AM_I);
473 	if (ret < 0)
474 		return ret;
475 	if (ret != MAG3110_DEVICE_ID)
476 		return -ENODEV;
477 
478 	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
479 	if (!indio_dev)
480 		return -ENOMEM;
481 
482 	data = iio_priv(indio_dev);
483 	data->client = client;
484 	mutex_init(&data->lock);
485 
486 	i2c_set_clientdata(client, indio_dev);
487 	indio_dev->info = &mag3110_info;
488 	indio_dev->name = id->name;
489 	indio_dev->dev.parent = &client->dev;
490 	indio_dev->modes = INDIO_DIRECT_MODE;
491 	indio_dev->channels = mag3110_channels;
492 	indio_dev->num_channels = ARRAY_SIZE(mag3110_channels);
493 	indio_dev->available_scan_masks = mag3110_scan_masks;
494 
495 	data->ctrl_reg1 = MAG3110_CTRL_DR_DEFAULT << MAG3110_CTRL_DR_SHIFT;
496 	data->sleep_val = mag3110_calculate_sleep(data);
497 	if (data->sleep_val < 40)
498 		data->ctrl_reg1 |= MAG3110_CTRL_AC;
499 
500 	ret = mag3110_change_config(data, MAG3110_CTRL_REG1, data->ctrl_reg1);
501 	if (ret < 0)
502 		return ret;
503 
504 	ret = i2c_smbus_write_byte_data(client, MAG3110_CTRL_REG2,
505 		MAG3110_CTRL_AUTO_MRST_EN);
506 	if (ret < 0)
507 		goto standby_on_error;
508 
509 	ret = iio_triggered_buffer_setup(indio_dev, NULL,
510 		mag3110_trigger_handler, NULL);
511 	if (ret < 0)
512 		goto standby_on_error;
513 
514 	ret = iio_device_register(indio_dev);
515 	if (ret < 0)
516 		goto buffer_cleanup;
517 	return 0;
518 
519 buffer_cleanup:
520 	iio_triggered_buffer_cleanup(indio_dev);
521 standby_on_error:
522 	mag3110_standby(iio_priv(indio_dev));
523 	return ret;
524 }
525 
526 static int mag3110_remove(struct i2c_client *client)
527 {
528 	struct iio_dev *indio_dev = i2c_get_clientdata(client);
529 
530 	iio_device_unregister(indio_dev);
531 	iio_triggered_buffer_cleanup(indio_dev);
532 	mag3110_standby(iio_priv(indio_dev));
533 
534 	return 0;
535 }
536 
537 #ifdef CONFIG_PM_SLEEP
538 static int mag3110_suspend(struct device *dev)
539 {
540 	return mag3110_standby(iio_priv(i2c_get_clientdata(
541 		to_i2c_client(dev))));
542 }
543 
544 static int mag3110_resume(struct device *dev)
545 {
546 	struct mag3110_data *data = iio_priv(i2c_get_clientdata(
547 		to_i2c_client(dev)));
548 
549 	return i2c_smbus_write_byte_data(data->client, MAG3110_CTRL_REG1,
550 		data->ctrl_reg1);
551 }
552 
553 static SIMPLE_DEV_PM_OPS(mag3110_pm_ops, mag3110_suspend, mag3110_resume);
554 #define MAG3110_PM_OPS (&mag3110_pm_ops)
555 #else
556 #define MAG3110_PM_OPS NULL
557 #endif
558 
559 static const struct i2c_device_id mag3110_id[] = {
560 	{ "mag3110", 0 },
561 	{ }
562 };
563 MODULE_DEVICE_TABLE(i2c, mag3110_id);
564 
565 static const struct of_device_id mag3110_of_match[] = {
566 	{ .compatible = "fsl,mag3110" },
567 	{ }
568 };
569 MODULE_DEVICE_TABLE(of, mag3110_of_match);
570 
571 static struct i2c_driver mag3110_driver = {
572 	.driver = {
573 		.name	= "mag3110",
574 		.of_match_table = mag3110_of_match,
575 		.pm	= MAG3110_PM_OPS,
576 	},
577 	.probe = mag3110_probe,
578 	.remove = mag3110_remove,
579 	.id_table = mag3110_id,
580 };
581 module_i2c_driver(mag3110_driver);
582 
583 MODULE_AUTHOR("Peter Meerwald <pmeerw@pmeerw.net>");
584 MODULE_DESCRIPTION("Freescale MAG3110 magnetometer driver");
585 MODULE_LICENSE("GPL");
586