Stuck at home?

Check our new online training!

Stuck at home?

All Bootlin training courses
are now available
through on-line seminars

Bootlin logo

Elixir Cross Referencer

  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
/*
 * MMC35240 - MEMSIC 3-axis Magnetic Sensor
 *
 * Copyright (c) 2015, Intel Corporation.
 *
 * 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.
 *
 * IIO driver for MMC35240 (7-bit I2C slave address 0x30).
 *
 * TODO: offset, ACPI, continuous measurement mode, PM
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/i2c.h>
#include <linux/delay.h>
#include <linux/regmap.h>
#include <linux/acpi.h>
#include <linux/pm.h>

#include <linux/iio/iio.h>
#include <linux/iio/sysfs.h>

#define MMC35240_DRV_NAME "mmc35240"
#define MMC35240_REGMAP_NAME "mmc35240_regmap"

#define MMC35240_REG_XOUT_L	0x00
#define MMC35240_REG_XOUT_H	0x01
#define MMC35240_REG_YOUT_L	0x02
#define MMC35240_REG_YOUT_H	0x03
#define MMC35240_REG_ZOUT_L	0x04
#define MMC35240_REG_ZOUT_H	0x05

#define MMC35240_REG_STATUS	0x06
#define MMC35240_REG_CTRL0	0x07
#define MMC35240_REG_CTRL1	0x08

#define MMC35240_REG_ID		0x20

#define MMC35240_STATUS_MEAS_DONE_BIT	BIT(0)

#define MMC35240_CTRL0_REFILL_BIT	BIT(7)
#define MMC35240_CTRL0_RESET_BIT	BIT(6)
#define MMC35240_CTRL0_SET_BIT		BIT(5)
#define MMC35240_CTRL0_CMM_BIT		BIT(1)
#define MMC35240_CTRL0_TM_BIT		BIT(0)

/* output resolution bits */
#define MMC35240_CTRL1_BW0_BIT		BIT(0)
#define MMC35240_CTRL1_BW1_BIT		BIT(1)

#define MMC35240_CTRL1_BW_MASK	 (MMC35240_CTRL1_BW0_BIT | \
		 MMC35240_CTRL1_BW1_BIT)
#define MMC35240_CTRL1_BW_SHIFT		0

#define MMC35240_WAIT_CHARGE_PUMP	50000	/* us */
#define MMC53240_WAIT_SET_RESET		1000	/* us */

/*
 * Memsic OTP process code piece is put here for reference:
 *
 * #define OTP_CONVERT(REG)  ((float)((REG) >=32 ? (32 - (REG)) : (REG)) * 0.006
 * 1) For X axis, the COEFFICIENT is always 1.
 * 2) For Y axis, the COEFFICIENT is as below:
 *    f_OTP_matrix[4] = OTP_CONVERT(((reg_data[1] & 0x03) << 4) |
 *                                   (reg_data[2] >> 4)) + 1.0;
 * 3) For Z axis, the COEFFICIENT is as below:
 *    f_OTP_matrix[8] = (OTP_CONVERT(reg_data[3] & 0x3f) + 1) * 1.35;
 * We implemented the OTP logic into driver.
 */

/* scale = 1000 here for Y otp */
#define MMC35240_OTP_CONVERT_Y(REG) (((REG) >= 32 ? (32 - (REG)) : (REG)) * 6)

/* 0.6 * 1.35 = 0.81, scale 10000 for Z otp */
#define MMC35240_OTP_CONVERT_Z(REG) (((REG) >= 32 ? (32 - (REG)) : (REG)) * 81)

#define MMC35240_X_COEFF(x)	(x)
#define MMC35240_Y_COEFF(y)	(y + 1000)
#define MMC35240_Z_COEFF(z)	(z + 13500)

#define MMC35240_OTP_START_ADDR		0x1B

enum mmc35240_resolution {
	MMC35240_16_BITS_SLOW = 0, /* 7.92 ms */
	MMC35240_16_BITS_FAST,     /* 4.08 ms */
	MMC35240_14_BITS,          /* 2.16 ms */
	MMC35240_12_BITS,          /* 1.20 ms */
};

enum mmc35240_axis {
	AXIS_X = 0,
	AXIS_Y,
	AXIS_Z,
};

static const struct {
	int sens[3]; /* sensitivity per X, Y, Z axis */
	int nfo; /* null field output */
} mmc35240_props_table[] = {
	/* 16 bits, 125Hz ODR */
	{
		{1024, 1024, 1024},
		32768,
	},
	/* 16 bits, 250Hz ODR */
	{
		{1024, 1024, 770},
		32768,
	},
	/* 14 bits, 450Hz ODR */
	{
		{256, 256, 193},
		8192,
	},
	/* 12 bits, 800Hz ODR */
	{
		{64, 64, 48},
		2048,
	},
};

struct mmc35240_data {
	struct i2c_client *client;
	struct mutex mutex;
	struct regmap *regmap;
	enum mmc35240_resolution res;

	/* OTP compensation */
	int axis_coef[3];
	int axis_scale[3];
};

static const struct {
	int val;
	int val2;
} mmc35240_samp_freq[] = { {1, 500000},
			   {13, 0},
			   {25, 0},
			   {50, 0} };

static IIO_CONST_ATTR_SAMP_FREQ_AVAIL("1.5 13 25 50");

#define MMC35240_CHANNEL(_axis) { \
	.type = IIO_MAGN, \
	.modified = 1, \
	.channel2 = IIO_MOD_ ## _axis, \
	.address = AXIS_ ## _axis, \
	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SAMP_FREQ) | \
			BIT(IIO_CHAN_INFO_SCALE), \
}

static const struct iio_chan_spec mmc35240_channels[] = {
	MMC35240_CHANNEL(X),
	MMC35240_CHANNEL(Y),
	MMC35240_CHANNEL(Z),
};

static struct attribute *mmc35240_attributes[] = {
	&iio_const_attr_sampling_frequency_available.dev_attr.attr,
	NULL
};

static const struct attribute_group mmc35240_attribute_group = {
	.attrs = mmc35240_attributes,
};

static int mmc35240_get_samp_freq_index(struct mmc35240_data *data,
					int val, int val2)
{
	int i;

	for (i = 0; i < ARRAY_SIZE(mmc35240_samp_freq); i++)
		if (mmc35240_samp_freq[i].val == val &&
		    mmc35240_samp_freq[i].val2 == val2)
			return i;
	return -EINVAL;
}

static int mmc35240_hw_set(struct mmc35240_data *data, bool set)
{
	int ret;
	u8 coil_bit;

	/*
	 * Recharge the capacitor at VCAP pin, requested to be issued
	 * before a SET/RESET command.
	 */
	ret = regmap_update_bits(data->regmap, MMC35240_REG_CTRL0,
				 MMC35240_CTRL0_REFILL_BIT,
				 MMC35240_CTRL0_REFILL_BIT);
	if (ret < 0)
		return ret;
	usleep_range(MMC35240_WAIT_CHARGE_PUMP, MMC35240_WAIT_CHARGE_PUMP + 1);

	if (set)
		coil_bit = MMC35240_CTRL0_SET_BIT;
	else
		coil_bit = MMC35240_CTRL0_RESET_BIT;

	return regmap_update_bits(data->regmap, MMC35240_REG_CTRL0,
				  coil_bit, coil_bit);

}

static int mmc35240_init(struct mmc35240_data *data)
{
	int ret, y_convert, z_convert;
	unsigned int reg_id;
	u8 otp_data[6];

	ret = regmap_read(data->regmap, MMC35240_REG_ID, &reg_id);
	if (ret < 0) {
		dev_err(&data->client->dev, "Error reading product id\n");
		return ret;
	}

	dev_dbg(&data->client->dev, "MMC35240 chip id %x\n", reg_id);

	/*
	 * make sure we restore sensor characteristics, by doing
	 * a SET/RESET sequence, the axis polarity being naturally
	 * aligned after RESET
	 */
	ret = mmc35240_hw_set(data, true);
	if (ret < 0)
		return ret;
	usleep_range(MMC53240_WAIT_SET_RESET, MMC53240_WAIT_SET_RESET + 1);

	ret = mmc35240_hw_set(data, false);
	if (ret < 0)
		return ret;

	/* set default sampling frequency */
	ret = regmap_update_bits(data->regmap, MMC35240_REG_CTRL1,
				 MMC35240_CTRL1_BW_MASK,
				 data->res << MMC35240_CTRL1_BW_SHIFT);
	if (ret < 0)
		return ret;

	ret = regmap_bulk_read(data->regmap, MMC35240_OTP_START_ADDR,
			       (u8 *)otp_data, sizeof(otp_data));
	if (ret < 0)
		return ret;

	y_convert = MMC35240_OTP_CONVERT_Y(((otp_data[1] & 0x03) << 4) |
					   (otp_data[2] >> 4));
	z_convert = MMC35240_OTP_CONVERT_Z(otp_data[3] & 0x3f);

	data->axis_coef[0] = MMC35240_X_COEFF(1);
	data->axis_coef[1] = MMC35240_Y_COEFF(y_convert);
	data->axis_coef[2] = MMC35240_Z_COEFF(z_convert);

	data->axis_scale[0] = 1;
	data->axis_scale[1] = 1000;
	data->axis_scale[2] = 10000;

	return 0;
}

static int mmc35240_take_measurement(struct mmc35240_data *data)
{
	int ret, tries = 100;
	unsigned int reg_status;

	ret = regmap_write(data->regmap, MMC35240_REG_CTRL0,
			   MMC35240_CTRL0_TM_BIT);
	if (ret < 0)
		return ret;

	while (tries-- > 0) {
		ret = regmap_read(data->regmap, MMC35240_REG_STATUS,
				  &reg_status);
		if (ret < 0)
			return ret;
		if (reg_status & MMC35240_STATUS_MEAS_DONE_BIT)
			break;
		/* minimum wait time to complete measurement is 10 ms */
		usleep_range(10000, 11000);
	}

	if (tries < 0) {
		dev_err(&data->client->dev, "data not ready\n");
		return -EIO;
	}

	return 0;
}

static int mmc35240_read_measurement(struct mmc35240_data *data, __le16 buf[3])
{
	int ret;

	ret = mmc35240_take_measurement(data);
	if (ret < 0)
		return ret;

	return regmap_bulk_read(data->regmap, MMC35240_REG_XOUT_L, (u8 *)buf,
				3 * sizeof(__le16));
}

/**
 * mmc35240_raw_to_mgauss - convert raw readings to milli gauss. Also apply
			    compensation for output value.
 *
 * @data: device private data
 * @index: axis index for which we want the conversion
 * @buf: raw data to be converted, 2 bytes in little endian format
 * @val: compensated output reading (unit is milli gauss)
 *
 * Returns: 0 in case of success, -EINVAL when @index is not valid
 */
static int mmc35240_raw_to_mgauss(struct mmc35240_data *data, int index,
				  __le16 buf[], int *val)
{
	int raw[3];
	int sens[3];
	int nfo;

	raw[AXIS_X] = le16_to_cpu(buf[AXIS_X]);
	raw[AXIS_Y] = le16_to_cpu(buf[AXIS_Y]);
	raw[AXIS_Z] = le16_to_cpu(buf[AXIS_Z]);

	sens[AXIS_X] = mmc35240_props_table[data->res].sens[AXIS_X];
	sens[AXIS_Y] = mmc35240_props_table[data->res].sens[AXIS_Y];
	sens[AXIS_Z] = mmc35240_props_table[data->res].sens[AXIS_Z];

	nfo = mmc35240_props_table[data->res].nfo;

	switch (index) {
	case AXIS_X:
		*val = (raw[AXIS_X] - nfo) * 1000 / sens[AXIS_X];
		break;
	case AXIS_Y:
		*val = (raw[AXIS_Y] - nfo) * 1000 / sens[AXIS_Y] -
			(raw[AXIS_Z] - nfo)  * 1000 / sens[AXIS_Z];
		break;
	case AXIS_Z:
		*val = (raw[AXIS_Y] - nfo) * 1000 / sens[AXIS_Y] +
			(raw[AXIS_Z] - nfo) * 1000 / sens[AXIS_Z];
		break;
	default:
		return -EINVAL;
	}
	/* apply OTP compensation */
	*val = (*val) * data->axis_coef[index] / data->axis_scale[index];

	return 0;
}

static int mmc35240_read_raw(struct iio_dev *indio_dev,
			     struct iio_chan_spec const *chan, int *val,
			     int *val2, long mask)
{
	struct mmc35240_data *data = iio_priv(indio_dev);
	int ret, i;
	unsigned int reg;
	__le16 buf[3];

	switch (mask) {
	case IIO_CHAN_INFO_RAW:
		mutex_lock(&data->mutex);
		ret = mmc35240_read_measurement(data, buf);
		mutex_unlock(&data->mutex);
		if (ret < 0)
			return ret;
		ret = mmc35240_raw_to_mgauss(data, chan->address, buf, val);
		if (ret < 0)
			return ret;
		return IIO_VAL_INT;
	case IIO_CHAN_INFO_SCALE:
		*val = 0;
		*val2 = 1000;
		return IIO_VAL_INT_PLUS_MICRO;
	case IIO_CHAN_INFO_SAMP_FREQ:
		mutex_lock(&data->mutex);
		ret = regmap_read(data->regmap, MMC35240_REG_CTRL1, &reg);
		mutex_unlock(&data->mutex);
		if (ret < 0)
			return ret;

		i = (reg & MMC35240_CTRL1_BW_MASK) >> MMC35240_CTRL1_BW_SHIFT;
		if (i < 0 || i >= ARRAY_SIZE(mmc35240_samp_freq))
			return -EINVAL;

		*val = mmc35240_samp_freq[i].val;
		*val2 = mmc35240_samp_freq[i].val2;
		return IIO_VAL_INT_PLUS_MICRO;
	default:
		return -EINVAL;
	}
}

static int mmc35240_write_raw(struct iio_dev *indio_dev,
			      struct iio_chan_spec const *chan, int val,
			      int val2, long mask)
{
	struct mmc35240_data *data = iio_priv(indio_dev);
	int i, ret;

	switch (mask) {
	case IIO_CHAN_INFO_SAMP_FREQ:
		i = mmc35240_get_samp_freq_index(data, val, val2);
		if (i < 0)
			return -EINVAL;
		mutex_lock(&data->mutex);
		ret = regmap_update_bits(data->regmap, MMC35240_REG_CTRL1,
					 MMC35240_CTRL1_BW_MASK,
					 i << MMC35240_CTRL1_BW_SHIFT);
		mutex_unlock(&data->mutex);
		return ret;
	default:
		return -EINVAL;
	}
}

static const struct iio_info mmc35240_info = {
	.driver_module	= THIS_MODULE,
	.read_raw	= mmc35240_read_raw,
	.write_raw	= mmc35240_write_raw,
	.attrs		= &mmc35240_attribute_group,
};

static bool mmc35240_is_writeable_reg(struct device *dev, unsigned int reg)
{
	switch (reg) {
	case MMC35240_REG_CTRL0:
	case MMC35240_REG_CTRL1:
		return true;
	default:
		return false;
	}
}

static bool mmc35240_is_readable_reg(struct device *dev, unsigned int reg)
{
	switch (reg) {
	case MMC35240_REG_XOUT_L:
	case MMC35240_REG_XOUT_H:
	case MMC35240_REG_YOUT_L:
	case MMC35240_REG_YOUT_H:
	case MMC35240_REG_ZOUT_L:
	case MMC35240_REG_ZOUT_H:
	case MMC35240_REG_STATUS:
	case MMC35240_REG_ID:
		return true;
	default:
		return false;
	}
}

static bool mmc35240_is_volatile_reg(struct device *dev, unsigned int reg)
{
	switch (reg) {
	case MMC35240_REG_CTRL0:
	case MMC35240_REG_CTRL1:
		return false;
	default:
		return true;
	}
}

static struct reg_default mmc35240_reg_defaults[] = {
	{ MMC35240_REG_CTRL0,  0x00 },
	{ MMC35240_REG_CTRL1,  0x00 },
};

static const struct regmap_config mmc35240_regmap_config = {
	.name = MMC35240_REGMAP_NAME,

	.reg_bits = 8,
	.val_bits = 8,

	.max_register = MMC35240_REG_ID,
	.cache_type = REGCACHE_FLAT,

	.writeable_reg = mmc35240_is_writeable_reg,
	.readable_reg = mmc35240_is_readable_reg,
	.volatile_reg = mmc35240_is_volatile_reg,

	.reg_defaults = mmc35240_reg_defaults,
	.num_reg_defaults = ARRAY_SIZE(mmc35240_reg_defaults),
};

static int mmc35240_probe(struct i2c_client *client,
			  const struct i2c_device_id *id)
{
	struct mmc35240_data *data;
	struct iio_dev *indio_dev;
	struct regmap *regmap;
	int ret;

	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
	if (!indio_dev)
		return -ENOMEM;

	regmap = devm_regmap_init_i2c(client, &mmc35240_regmap_config);
	if (IS_ERR(regmap)) {
		dev_err(&client->dev, "regmap initialization failed\n");
		return PTR_ERR(regmap);
	}

	data = iio_priv(indio_dev);
	i2c_set_clientdata(client, indio_dev);
	data->client = client;
	data->regmap = regmap;
	data->res = MMC35240_16_BITS_SLOW;

	mutex_init(&data->mutex);

	indio_dev->dev.parent = &client->dev;
	indio_dev->info = &mmc35240_info;
	indio_dev->name = MMC35240_DRV_NAME;
	indio_dev->channels = mmc35240_channels;
	indio_dev->num_channels = ARRAY_SIZE(mmc35240_channels);
	indio_dev->modes = INDIO_DIRECT_MODE;

	ret = mmc35240_init(data);
	if (ret < 0) {
		dev_err(&client->dev, "mmc35240 chip init failed\n");
		return ret;
	}
	return devm_iio_device_register(&client->dev, indio_dev);
}

#ifdef CONFIG_PM_SLEEP
static int mmc35240_suspend(struct device *dev)
{
	struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
	struct mmc35240_data *data = iio_priv(indio_dev);

	regcache_cache_only(data->regmap, true);

	return 0;
}

static int mmc35240_resume(struct device *dev)
{
	struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
	struct mmc35240_data *data = iio_priv(indio_dev);
	int ret;

	regcache_mark_dirty(data->regmap);
	ret = regcache_sync_region(data->regmap, MMC35240_REG_CTRL0,
				   MMC35240_REG_CTRL1);
	if (ret < 0)
		dev_err(dev, "Failed to restore control registers\n");

	regcache_cache_only(data->regmap, false);

	return 0;
}
#endif

static const struct dev_pm_ops mmc35240_pm_ops = {
	SET_SYSTEM_SLEEP_PM_OPS(mmc35240_suspend, mmc35240_resume)
};

static const struct of_device_id mmc35240_of_match[] = {
	{ .compatible = "memsic,mmc35240", },
	{ }
};
MODULE_DEVICE_TABLE(of, mmc35240_of_match);

static const struct acpi_device_id mmc35240_acpi_match[] = {
	{"MMC35240", 0},
	{ },
};
MODULE_DEVICE_TABLE(acpi, mmc35240_acpi_match);

static const struct i2c_device_id mmc35240_id[] = {
	{"mmc35240", 0},
	{}
};
MODULE_DEVICE_TABLE(i2c, mmc35240_id);

static struct i2c_driver mmc35240_driver = {
	.driver = {
		.name = MMC35240_DRV_NAME,
		.of_match_table = mmc35240_of_match,
		.pm = &mmc35240_pm_ops,
		.acpi_match_table = ACPI_PTR(mmc35240_acpi_match),
	},
	.probe		= mmc35240_probe,
	.id_table	= mmc35240_id,
};

module_i2c_driver(mmc35240_driver);

MODULE_AUTHOR("Daniel Baluta <daniel.baluta@intel.com>");
MODULE_DESCRIPTION("MEMSIC MMC35240 magnetic sensor driver");
MODULE_LICENSE("GPL v2");