1 /*
2  * MMC35240 - MEMSIC 3-axis Magnetic Sensor
3  *
4  * Copyright (c) 2015, Intel Corporation.
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  * IIO driver for MMC35240 (7-bit I2C slave address 0x30).
11  *
12  * TODO: offset, ACPI, continuous measurement mode, PM
13  */
14 
15 #include <linux/module.h>
16 #include <linux/init.h>
17 #include <linux/i2c.h>
18 #include <linux/delay.h>
19 #include <linux/regmap.h>
20 #include <linux/acpi.h>
21 #include <linux/pm.h>
22 
23 #include <linux/iio/iio.h>
24 #include <linux/iio/sysfs.h>
25 
26 #define MMC35240_DRV_NAME "mmc35240"
27 #define MMC35240_REGMAP_NAME "mmc35240_regmap"
28 
29 #define MMC35240_REG_XOUT_L	0x00
30 #define MMC35240_REG_XOUT_H	0x01
31 #define MMC35240_REG_YOUT_L	0x02
32 #define MMC35240_REG_YOUT_H	0x03
33 #define MMC35240_REG_ZOUT_L	0x04
34 #define MMC35240_REG_ZOUT_H	0x05
35 
36 #define MMC35240_REG_STATUS	0x06
37 #define MMC35240_REG_CTRL0	0x07
38 #define MMC35240_REG_CTRL1	0x08
39 
40 #define MMC35240_REG_ID		0x20
41 
42 #define MMC35240_STATUS_MEAS_DONE_BIT	BIT(0)
43 
44 #define MMC35240_CTRL0_REFILL_BIT	BIT(7)
45 #define MMC35240_CTRL0_RESET_BIT	BIT(6)
46 #define MMC35240_CTRL0_SET_BIT		BIT(5)
47 #define MMC35240_CTRL0_CMM_BIT		BIT(1)
48 #define MMC35240_CTRL0_TM_BIT		BIT(0)
49 
50 /* output resolution bits */
51 #define MMC35240_CTRL1_BW0_BIT		BIT(0)
52 #define MMC35240_CTRL1_BW1_BIT		BIT(1)
53 
54 #define MMC35240_CTRL1_BW_MASK	 (MMC35240_CTRL1_BW0_BIT | \
55 		 MMC35240_CTRL1_BW1_BIT)
56 #define MMC35240_CTRL1_BW_SHIFT		0
57 
58 #define MMC35240_WAIT_CHARGE_PUMP	50000	/* us */
59 #define MMC53240_WAIT_SET_RESET		1000	/* us */
60 
61 /*
62  * Memsic OTP process code piece is put here for reference:
63  *
64  * #define OTP_CONVERT(REG)  ((float)((REG) >=32 ? (32 - (REG)) : (REG)) * 0.006
65  * 1) For X axis, the COEFFICIENT is always 1.
66  * 2) For Y axis, the COEFFICIENT is as below:
67  *    f_OTP_matrix[4] = OTP_CONVERT(((reg_data[1] & 0x03) << 4) |
68  *                                   (reg_data[2] >> 4)) + 1.0;
69  * 3) For Z axis, the COEFFICIENT is as below:
70  *    f_OTP_matrix[8] = (OTP_CONVERT(reg_data[3] & 0x3f) + 1) * 1.35;
71  * We implemented the OTP logic into driver.
72  */
73 
74 /* scale = 1000 here for Y otp */
75 #define MMC35240_OTP_CONVERT_Y(REG) (((REG) >= 32 ? (32 - (REG)) : (REG)) * 6)
76 
77 /* 0.6 * 1.35 = 0.81, scale 10000 for Z otp */
78 #define MMC35240_OTP_CONVERT_Z(REG) (((REG) >= 32 ? (32 - (REG)) : (REG)) * 81)
79 
80 #define MMC35240_X_COEFF(x)	(x)
81 #define MMC35240_Y_COEFF(y)	(y + 1000)
82 #define MMC35240_Z_COEFF(z)	(z + 13500)
83 
84 #define MMC35240_OTP_START_ADDR		0x1B
85 
86 enum mmc35240_resolution {
87 	MMC35240_16_BITS_SLOW = 0, /* 7.92 ms */
88 	MMC35240_16_BITS_FAST,     /* 4.08 ms */
89 	MMC35240_14_BITS,          /* 2.16 ms */
90 	MMC35240_12_BITS,          /* 1.20 ms */
91 };
92 
93 enum mmc35240_axis {
94 	AXIS_X = 0,
95 	AXIS_Y,
96 	AXIS_Z,
97 };
98 
99 static const struct {
100 	int sens[3]; /* sensitivity per X, Y, Z axis */
101 	int nfo; /* null field output */
102 } mmc35240_props_table[] = {
103 	/* 16 bits, 125Hz ODR */
104 	{
105 		{1024, 1024, 1024},
106 		32768,
107 	},
108 	/* 16 bits, 250Hz ODR */
109 	{
110 		{1024, 1024, 770},
111 		32768,
112 	},
113 	/* 14 bits, 450Hz ODR */
114 	{
115 		{256, 256, 193},
116 		8192,
117 	},
118 	/* 12 bits, 800Hz ODR */
119 	{
120 		{64, 64, 48},
121 		2048,
122 	},
123 };
124 
125 struct mmc35240_data {
126 	struct i2c_client *client;
127 	struct mutex mutex;
128 	struct regmap *regmap;
129 	enum mmc35240_resolution res;
130 
131 	/* OTP compensation */
132 	int axis_coef[3];
133 	int axis_scale[3];
134 };
135 
136 static const struct {
137 	int val;
138 	int val2;
139 } mmc35240_samp_freq[] = { {1, 500000},
140 			   {13, 0},
141 			   {25, 0},
142 			   {50, 0} };
143 
144 static IIO_CONST_ATTR_SAMP_FREQ_AVAIL("1.5 13 25 50");
145 
146 #define MMC35240_CHANNEL(_axis) { \
147 	.type = IIO_MAGN, \
148 	.modified = 1, \
149 	.channel2 = IIO_MOD_ ## _axis, \
150 	.address = AXIS_ ## _axis, \
151 	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
152 	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SAMP_FREQ) | \
153 			BIT(IIO_CHAN_INFO_SCALE), \
154 }
155 
156 static const struct iio_chan_spec mmc35240_channels[] = {
157 	MMC35240_CHANNEL(X),
158 	MMC35240_CHANNEL(Y),
159 	MMC35240_CHANNEL(Z),
160 };
161 
162 static struct attribute *mmc35240_attributes[] = {
163 	&iio_const_attr_sampling_frequency_available.dev_attr.attr,
164 	NULL
165 };
166 
167 static const struct attribute_group mmc35240_attribute_group = {
168 	.attrs = mmc35240_attributes,
169 };
170 
171 static int mmc35240_get_samp_freq_index(struct mmc35240_data *data,
172 					int val, int val2)
173 {
174 	int i;
175 
176 	for (i = 0; i < ARRAY_SIZE(mmc35240_samp_freq); i++)
177 		if (mmc35240_samp_freq[i].val == val &&
178 		    mmc35240_samp_freq[i].val2 == val2)
179 			return i;
180 	return -EINVAL;
181 }
182 
183 static int mmc35240_hw_set(struct mmc35240_data *data, bool set)
184 {
185 	int ret;
186 	u8 coil_bit;
187 
188 	/*
189 	 * Recharge the capacitor at VCAP pin, requested to be issued
190 	 * before a SET/RESET command.
191 	 */
192 	ret = regmap_update_bits(data->regmap, MMC35240_REG_CTRL0,
193 				 MMC35240_CTRL0_REFILL_BIT,
194 				 MMC35240_CTRL0_REFILL_BIT);
195 	if (ret < 0)
196 		return ret;
197 	usleep_range(MMC35240_WAIT_CHARGE_PUMP, MMC35240_WAIT_CHARGE_PUMP + 1);
198 
199 	if (set)
200 		coil_bit = MMC35240_CTRL0_SET_BIT;
201 	else
202 		coil_bit = MMC35240_CTRL0_RESET_BIT;
203 
204 	return regmap_update_bits(data->regmap, MMC35240_REG_CTRL0,
205 				  coil_bit, coil_bit);
206 
207 }
208 
209 static int mmc35240_init(struct mmc35240_data *data)
210 {
211 	int ret, y_convert, z_convert;
212 	unsigned int reg_id;
213 	u8 otp_data[6];
214 
215 	ret = regmap_read(data->regmap, MMC35240_REG_ID, &reg_id);
216 	if (ret < 0) {
217 		dev_err(&data->client->dev, "Error reading product id\n");
218 		return ret;
219 	}
220 
221 	dev_dbg(&data->client->dev, "MMC35240 chip id %x\n", reg_id);
222 
223 	/*
224 	 * make sure we restore sensor characteristics, by doing
225 	 * a SET/RESET sequence, the axis polarity being naturally
226 	 * aligned after RESET
227 	 */
228 	ret = mmc35240_hw_set(data, true);
229 	if (ret < 0)
230 		return ret;
231 	usleep_range(MMC53240_WAIT_SET_RESET, MMC53240_WAIT_SET_RESET + 1);
232 
233 	ret = mmc35240_hw_set(data, false);
234 	if (ret < 0)
235 		return ret;
236 
237 	/* set default sampling frequency */
238 	ret = regmap_update_bits(data->regmap, MMC35240_REG_CTRL1,
239 				 MMC35240_CTRL1_BW_MASK,
240 				 data->res << MMC35240_CTRL1_BW_SHIFT);
241 	if (ret < 0)
242 		return ret;
243 
244 	ret = regmap_bulk_read(data->regmap, MMC35240_OTP_START_ADDR,
245 			       (u8 *)otp_data, sizeof(otp_data));
246 	if (ret < 0)
247 		return ret;
248 
249 	y_convert = MMC35240_OTP_CONVERT_Y(((otp_data[1] & 0x03) << 4) |
250 					   (otp_data[2] >> 4));
251 	z_convert = MMC35240_OTP_CONVERT_Z(otp_data[3] & 0x3f);
252 
253 	data->axis_coef[0] = MMC35240_X_COEFF(1);
254 	data->axis_coef[1] = MMC35240_Y_COEFF(y_convert);
255 	data->axis_coef[2] = MMC35240_Z_COEFF(z_convert);
256 
257 	data->axis_scale[0] = 1;
258 	data->axis_scale[1] = 1000;
259 	data->axis_scale[2] = 10000;
260 
261 	return 0;
262 }
263 
264 static int mmc35240_take_measurement(struct mmc35240_data *data)
265 {
266 	int ret, tries = 100;
267 	unsigned int reg_status;
268 
269 	ret = regmap_write(data->regmap, MMC35240_REG_CTRL0,
270 			   MMC35240_CTRL0_TM_BIT);
271 	if (ret < 0)
272 		return ret;
273 
274 	while (tries-- > 0) {
275 		ret = regmap_read(data->regmap, MMC35240_REG_STATUS,
276 				  &reg_status);
277 		if (ret < 0)
278 			return ret;
279 		if (reg_status & MMC35240_STATUS_MEAS_DONE_BIT)
280 			break;
281 		/* minimum wait time to complete measurement is 10 ms */
282 		usleep_range(10000, 11000);
283 	}
284 
285 	if (tries < 0) {
286 		dev_err(&data->client->dev, "data not ready\n");
287 		return -EIO;
288 	}
289 
290 	return 0;
291 }
292 
293 static int mmc35240_read_measurement(struct mmc35240_data *data, __le16 buf[3])
294 {
295 	int ret;
296 
297 	ret = mmc35240_take_measurement(data);
298 	if (ret < 0)
299 		return ret;
300 
301 	return regmap_bulk_read(data->regmap, MMC35240_REG_XOUT_L, (u8 *)buf,
302 				3 * sizeof(__le16));
303 }
304 
305 /**
306  * mmc35240_raw_to_mgauss - convert raw readings to milli gauss. Also apply
307 			    compensation for output value.
308  *
309  * @data: device private data
310  * @index: axis index for which we want the conversion
311  * @buf: raw data to be converted, 2 bytes in little endian format
312  * @val: compensated output reading (unit is milli gauss)
313  *
314  * Returns: 0 in case of success, -EINVAL when @index is not valid
315  */
316 static int mmc35240_raw_to_mgauss(struct mmc35240_data *data, int index,
317 				  __le16 buf[], int *val)
318 {
319 	int raw[3];
320 	int sens[3];
321 	int nfo;
322 
323 	raw[AXIS_X] = le16_to_cpu(buf[AXIS_X]);
324 	raw[AXIS_Y] = le16_to_cpu(buf[AXIS_Y]);
325 	raw[AXIS_Z] = le16_to_cpu(buf[AXIS_Z]);
326 
327 	sens[AXIS_X] = mmc35240_props_table[data->res].sens[AXIS_X];
328 	sens[AXIS_Y] = mmc35240_props_table[data->res].sens[AXIS_Y];
329 	sens[AXIS_Z] = mmc35240_props_table[data->res].sens[AXIS_Z];
330 
331 	nfo = mmc35240_props_table[data->res].nfo;
332 
333 	switch (index) {
334 	case AXIS_X:
335 		*val = (raw[AXIS_X] - nfo) * 1000 / sens[AXIS_X];
336 		break;
337 	case AXIS_Y:
338 		*val = (raw[AXIS_Y] - nfo) * 1000 / sens[AXIS_Y] -
339 			(raw[AXIS_Z] - nfo)  * 1000 / sens[AXIS_Z];
340 		break;
341 	case AXIS_Z:
342 		*val = (raw[AXIS_Y] - nfo) * 1000 / sens[AXIS_Y] +
343 			(raw[AXIS_Z] - nfo) * 1000 / sens[AXIS_Z];
344 		break;
345 	default:
346 		return -EINVAL;
347 	}
348 	/* apply OTP compensation */
349 	*val = (*val) * data->axis_coef[index] / data->axis_scale[index];
350 
351 	return 0;
352 }
353 
354 static int mmc35240_read_raw(struct iio_dev *indio_dev,
355 			     struct iio_chan_spec const *chan, int *val,
356 			     int *val2, long mask)
357 {
358 	struct mmc35240_data *data = iio_priv(indio_dev);
359 	int ret, i;
360 	unsigned int reg;
361 	__le16 buf[3];
362 
363 	switch (mask) {
364 	case IIO_CHAN_INFO_RAW:
365 		mutex_lock(&data->mutex);
366 		ret = mmc35240_read_measurement(data, buf);
367 		mutex_unlock(&data->mutex);
368 		if (ret < 0)
369 			return ret;
370 		ret = mmc35240_raw_to_mgauss(data, chan->address, buf, val);
371 		if (ret < 0)
372 			return ret;
373 		return IIO_VAL_INT;
374 	case IIO_CHAN_INFO_SCALE:
375 		*val = 0;
376 		*val2 = 1000;
377 		return IIO_VAL_INT_PLUS_MICRO;
378 	case IIO_CHAN_INFO_SAMP_FREQ:
379 		mutex_lock(&data->mutex);
380 		ret = regmap_read(data->regmap, MMC35240_REG_CTRL1, &reg);
381 		mutex_unlock(&data->mutex);
382 		if (ret < 0)
383 			return ret;
384 
385 		i = (reg & MMC35240_CTRL1_BW_MASK) >> MMC35240_CTRL1_BW_SHIFT;
386 		if (i < 0 || i >= ARRAY_SIZE(mmc35240_samp_freq))
387 			return -EINVAL;
388 
389 		*val = mmc35240_samp_freq[i].val;
390 		*val2 = mmc35240_samp_freq[i].val2;
391 		return IIO_VAL_INT_PLUS_MICRO;
392 	default:
393 		return -EINVAL;
394 	}
395 }
396 
397 static int mmc35240_write_raw(struct iio_dev *indio_dev,
398 			      struct iio_chan_spec const *chan, int val,
399 			      int val2, long mask)
400 {
401 	struct mmc35240_data *data = iio_priv(indio_dev);
402 	int i, ret;
403 
404 	switch (mask) {
405 	case IIO_CHAN_INFO_SAMP_FREQ:
406 		i = mmc35240_get_samp_freq_index(data, val, val2);
407 		if (i < 0)
408 			return -EINVAL;
409 		mutex_lock(&data->mutex);
410 		ret = regmap_update_bits(data->regmap, MMC35240_REG_CTRL1,
411 					 MMC35240_CTRL1_BW_MASK,
412 					 i << MMC35240_CTRL1_BW_SHIFT);
413 		mutex_unlock(&data->mutex);
414 		return ret;
415 	default:
416 		return -EINVAL;
417 	}
418 }
419 
420 static const struct iio_info mmc35240_info = {
421 	.read_raw	= mmc35240_read_raw,
422 	.write_raw	= mmc35240_write_raw,
423 	.attrs		= &mmc35240_attribute_group,
424 };
425 
426 static bool mmc35240_is_writeable_reg(struct device *dev, unsigned int reg)
427 {
428 	switch (reg) {
429 	case MMC35240_REG_CTRL0:
430 	case MMC35240_REG_CTRL1:
431 		return true;
432 	default:
433 		return false;
434 	}
435 }
436 
437 static bool mmc35240_is_readable_reg(struct device *dev, unsigned int reg)
438 {
439 	switch (reg) {
440 	case MMC35240_REG_XOUT_L:
441 	case MMC35240_REG_XOUT_H:
442 	case MMC35240_REG_YOUT_L:
443 	case MMC35240_REG_YOUT_H:
444 	case MMC35240_REG_ZOUT_L:
445 	case MMC35240_REG_ZOUT_H:
446 	case MMC35240_REG_STATUS:
447 	case MMC35240_REG_ID:
448 		return true;
449 	default:
450 		return false;
451 	}
452 }
453 
454 static bool mmc35240_is_volatile_reg(struct device *dev, unsigned int reg)
455 {
456 	switch (reg) {
457 	case MMC35240_REG_CTRL0:
458 	case MMC35240_REG_CTRL1:
459 		return false;
460 	default:
461 		return true;
462 	}
463 }
464 
465 static struct reg_default mmc35240_reg_defaults[] = {
466 	{ MMC35240_REG_CTRL0,  0x00 },
467 	{ MMC35240_REG_CTRL1,  0x00 },
468 };
469 
470 static const struct regmap_config mmc35240_regmap_config = {
471 	.name = MMC35240_REGMAP_NAME,
472 
473 	.reg_bits = 8,
474 	.val_bits = 8,
475 
476 	.max_register = MMC35240_REG_ID,
477 	.cache_type = REGCACHE_FLAT,
478 
479 	.writeable_reg = mmc35240_is_writeable_reg,
480 	.readable_reg = mmc35240_is_readable_reg,
481 	.volatile_reg = mmc35240_is_volatile_reg,
482 
483 	.reg_defaults = mmc35240_reg_defaults,
484 	.num_reg_defaults = ARRAY_SIZE(mmc35240_reg_defaults),
485 };
486 
487 static int mmc35240_probe(struct i2c_client *client,
488 			  const struct i2c_device_id *id)
489 {
490 	struct mmc35240_data *data;
491 	struct iio_dev *indio_dev;
492 	struct regmap *regmap;
493 	int ret;
494 
495 	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
496 	if (!indio_dev)
497 		return -ENOMEM;
498 
499 	regmap = devm_regmap_init_i2c(client, &mmc35240_regmap_config);
500 	if (IS_ERR(regmap)) {
501 		dev_err(&client->dev, "regmap initialization failed\n");
502 		return PTR_ERR(regmap);
503 	}
504 
505 	data = iio_priv(indio_dev);
506 	i2c_set_clientdata(client, indio_dev);
507 	data->client = client;
508 	data->regmap = regmap;
509 	data->res = MMC35240_16_BITS_SLOW;
510 
511 	mutex_init(&data->mutex);
512 
513 	indio_dev->dev.parent = &client->dev;
514 	indio_dev->info = &mmc35240_info;
515 	indio_dev->name = MMC35240_DRV_NAME;
516 	indio_dev->channels = mmc35240_channels;
517 	indio_dev->num_channels = ARRAY_SIZE(mmc35240_channels);
518 	indio_dev->modes = INDIO_DIRECT_MODE;
519 
520 	ret = mmc35240_init(data);
521 	if (ret < 0) {
522 		dev_err(&client->dev, "mmc35240 chip init failed\n");
523 		return ret;
524 	}
525 	return devm_iio_device_register(&client->dev, indio_dev);
526 }
527 
528 #ifdef CONFIG_PM_SLEEP
529 static int mmc35240_suspend(struct device *dev)
530 {
531 	struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
532 	struct mmc35240_data *data = iio_priv(indio_dev);
533 
534 	regcache_cache_only(data->regmap, true);
535 
536 	return 0;
537 }
538 
539 static int mmc35240_resume(struct device *dev)
540 {
541 	struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
542 	struct mmc35240_data *data = iio_priv(indio_dev);
543 	int ret;
544 
545 	regcache_mark_dirty(data->regmap);
546 	ret = regcache_sync_region(data->regmap, MMC35240_REG_CTRL0,
547 				   MMC35240_REG_CTRL1);
548 	if (ret < 0)
549 		dev_err(dev, "Failed to restore control registers\n");
550 
551 	regcache_cache_only(data->regmap, false);
552 
553 	return 0;
554 }
555 #endif
556 
557 static const struct dev_pm_ops mmc35240_pm_ops = {
558 	SET_SYSTEM_SLEEP_PM_OPS(mmc35240_suspend, mmc35240_resume)
559 };
560 
561 static const struct of_device_id mmc35240_of_match[] = {
562 	{ .compatible = "memsic,mmc35240", },
563 	{ }
564 };
565 MODULE_DEVICE_TABLE(of, mmc35240_of_match);
566 
567 static const struct acpi_device_id mmc35240_acpi_match[] = {
568 	{"MMC35240", 0},
569 	{ },
570 };
571 MODULE_DEVICE_TABLE(acpi, mmc35240_acpi_match);
572 
573 static const struct i2c_device_id mmc35240_id[] = {
574 	{"mmc35240", 0},
575 	{}
576 };
577 MODULE_DEVICE_TABLE(i2c, mmc35240_id);
578 
579 static struct i2c_driver mmc35240_driver = {
580 	.driver = {
581 		.name = MMC35240_DRV_NAME,
582 		.of_match_table = mmc35240_of_match,
583 		.pm = &mmc35240_pm_ops,
584 		.acpi_match_table = ACPI_PTR(mmc35240_acpi_match),
585 	},
586 	.probe		= mmc35240_probe,
587 	.id_table	= mmc35240_id,
588 };
589 
590 module_i2c_driver(mmc35240_driver);
591 
592 MODULE_AUTHOR("Daniel Baluta <daniel.baluta@intel.com>");
593 MODULE_DESCRIPTION("MEMSIC MMC35240 magnetic sensor driver");
594 MODULE_LICENSE("GPL v2");
595