1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * MMC35240 - MEMSIC 3-axis Magnetic Sensor
4 *
5 * Copyright (c) 2015, Intel Corporation.
6 *
7 * IIO driver for MMC35240 (7-bit I2C slave address 0x30).
8 *
9 * TODO: offset, ACPI, continuous measurement mode, PM
10 */
11
12#include <linux/module.h>
13#include <linux/init.h>
14#include <linux/i2c.h>
15#include <linux/delay.h>
16#include <linux/regmap.h>
17#include <linux/acpi.h>
18#include <linux/pm.h>
19
20#include <linux/iio/iio.h>
21#include <linux/iio/sysfs.h>
22
23#define MMC35240_DRV_NAME "mmc35240"
24#define MMC35240_REGMAP_NAME "mmc35240_regmap"
25
26#define MMC35240_REG_XOUT_L	0x00
27#define MMC35240_REG_XOUT_H	0x01
28#define MMC35240_REG_YOUT_L	0x02
29#define MMC35240_REG_YOUT_H	0x03
30#define MMC35240_REG_ZOUT_L	0x04
31#define MMC35240_REG_ZOUT_H	0x05
32
33#define MMC35240_REG_STATUS	0x06
34#define MMC35240_REG_CTRL0	0x07
35#define MMC35240_REG_CTRL1	0x08
36
37#define MMC35240_REG_ID		0x20
38
39#define MMC35240_STATUS_MEAS_DONE_BIT	BIT(0)
40
41#define MMC35240_CTRL0_REFILL_BIT	BIT(7)
42#define MMC35240_CTRL0_RESET_BIT	BIT(6)
43#define MMC35240_CTRL0_SET_BIT		BIT(5)
44#define MMC35240_CTRL0_CMM_BIT		BIT(1)
45#define MMC35240_CTRL0_TM_BIT		BIT(0)
46
47/* output resolution bits */
48#define MMC35240_CTRL1_BW0_BIT		BIT(0)
49#define MMC35240_CTRL1_BW1_BIT		BIT(1)
50
51#define MMC35240_CTRL1_BW_MASK	 (MMC35240_CTRL1_BW0_BIT | \
52		 MMC35240_CTRL1_BW1_BIT)
53#define MMC35240_CTRL1_BW_SHIFT		0
54
55#define MMC35240_WAIT_CHARGE_PUMP	50000	/* us */
56#define MMC35240_WAIT_SET_RESET		1000	/* us */
57
58/*
59 * Memsic OTP process code piece is put here for reference:
60 *
61 * #define OTP_CONVERT(REG)  ((float)((REG) >=32 ? (32 - (REG)) : (REG)) * 0.006
62 * 1) For X axis, the COEFFICIENT is always 1.
63 * 2) For Y axis, the COEFFICIENT is as below:
64 *    f_OTP_matrix[4] = OTP_CONVERT(((reg_data[1] & 0x03) << 4) |
65 *                                   (reg_data[2] >> 4)) + 1.0;
66 * 3) For Z axis, the COEFFICIENT is as below:
67 *    f_OTP_matrix[8] = (OTP_CONVERT(reg_data[3] & 0x3f) + 1) * 1.35;
68 * We implemented the OTP logic into driver.
69 */
70
71/* scale = 1000 here for Y otp */
72#define MMC35240_OTP_CONVERT_Y(REG) (((REG) >= 32 ? (32 - (REG)) : (REG)) * 6)
73
74/* 0.6 * 1.35 = 0.81, scale 10000 for Z otp */
75#define MMC35240_OTP_CONVERT_Z(REG) (((REG) >= 32 ? (32 - (REG)) : (REG)) * 81)
76
77#define MMC35240_X_COEFF(x)	(x)
78#define MMC35240_Y_COEFF(y)	(y + 1000)
79#define MMC35240_Z_COEFF(z)	(z + 13500)
80
81#define MMC35240_OTP_START_ADDR		0x1B
82
83enum mmc35240_resolution {
84	MMC35240_16_BITS_SLOW = 0, /* 7.92 ms */
85	MMC35240_16_BITS_FAST,     /* 4.08 ms */
86	MMC35240_14_BITS,          /* 2.16 ms */
87	MMC35240_12_BITS,          /* 1.20 ms */
88};
89
90enum mmc35240_axis {
91	AXIS_X = 0,
92	AXIS_Y,
93	AXIS_Z,
94};
95
96static const struct {
97	int sens[3]; /* sensitivity per X, Y, Z axis */
98	int nfo; /* null field output */
99} mmc35240_props_table[] = {
100	/* 16 bits, 125Hz ODR */
101	{
102		{1024, 1024, 1024},
103		32768,
104	},
105	/* 16 bits, 250Hz ODR */
106	{
107		{1024, 1024, 770},
108		32768,
109	},
110	/* 14 bits, 450Hz ODR */
111	{
112		{256, 256, 193},
113		8192,
114	},
115	/* 12 bits, 800Hz ODR */
116	{
117		{64, 64, 48},
118		2048,
119	},
120};
121
122struct mmc35240_data {
123	struct i2c_client *client;
124	struct mutex mutex;
125	struct regmap *regmap;
126	enum mmc35240_resolution res;
127
128	/* OTP compensation */
129	int axis_coef[3];
130	int axis_scale[3];
131};
132
133static const struct {
134	int val;
135	int val2;
136} mmc35240_samp_freq[] = { {1, 500000},
137			   {13, 0},
138			   {25, 0},
139			   {50, 0} };
140
141static IIO_CONST_ATTR_SAMP_FREQ_AVAIL("1.5 13 25 50");
142
143#define MMC35240_CHANNEL(_axis) { \
144	.type = IIO_MAGN, \
145	.modified = 1, \
146	.channel2 = IIO_MOD_ ## _axis, \
147	.address = AXIS_ ## _axis, \
148	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
149	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SAMP_FREQ) | \
150			BIT(IIO_CHAN_INFO_SCALE), \
151}
152
153static const struct iio_chan_spec mmc35240_channels[] = {
154	MMC35240_CHANNEL(X),
155	MMC35240_CHANNEL(Y),
156	MMC35240_CHANNEL(Z),
157};
158
159static struct attribute *mmc35240_attributes[] = {
160	&iio_const_attr_sampling_frequency_available.dev_attr.attr,
161	NULL
162};
163
164static const struct attribute_group mmc35240_attribute_group = {
165	.attrs = mmc35240_attributes,
166};
167
168static int mmc35240_get_samp_freq_index(struct mmc35240_data *data,
169					int val, int val2)
170{
171	int i;
172
173	for (i = 0; i < ARRAY_SIZE(mmc35240_samp_freq); i++)
174		if (mmc35240_samp_freq[i].val == val &&
175		    mmc35240_samp_freq[i].val2 == val2)
176			return i;
177	return -EINVAL;
178}
179
180static int mmc35240_hw_set(struct mmc35240_data *data, bool set)
181{
182	int ret;
183	u8 coil_bit;
184
185	/*
186	 * Recharge the capacitor at VCAP pin, requested to be issued
187	 * before a SET/RESET command.
188	 */
189	ret = regmap_update_bits(data->regmap, MMC35240_REG_CTRL0,
190				 MMC35240_CTRL0_REFILL_BIT,
191				 MMC35240_CTRL0_REFILL_BIT);
192	if (ret < 0)
193		return ret;
194	usleep_range(MMC35240_WAIT_CHARGE_PUMP, MMC35240_WAIT_CHARGE_PUMP + 1);
195
196	if (set)
197		coil_bit = MMC35240_CTRL0_SET_BIT;
198	else
199		coil_bit = MMC35240_CTRL0_RESET_BIT;
200
201	return regmap_update_bits(data->regmap, MMC35240_REG_CTRL0,
202				  coil_bit, coil_bit);
203
204}
205
206static int mmc35240_init(struct mmc35240_data *data)
207{
208	int ret, y_convert, z_convert;
209	unsigned int reg_id;
210	u8 otp_data[6];
211
212	ret = regmap_read(data->regmap, MMC35240_REG_ID, &reg_id);
213	if (ret < 0) {
214		dev_err(&data->client->dev, "Error reading product id\n");
215		return ret;
216	}
217
218	dev_dbg(&data->client->dev, "MMC35240 chip id %x\n", reg_id);
219
220	/*
221	 * make sure we restore sensor characteristics, by doing
222	 * a SET/RESET sequence, the axis polarity being naturally
223	 * aligned after RESET
224	 */
225	ret = mmc35240_hw_set(data, true);
226	if (ret < 0)
227		return ret;
228	usleep_range(MMC35240_WAIT_SET_RESET, MMC35240_WAIT_SET_RESET + 1);
229
230	ret = mmc35240_hw_set(data, false);
231	if (ret < 0)
232		return ret;
233
234	/* set default sampling frequency */
235	ret = regmap_update_bits(data->regmap, MMC35240_REG_CTRL1,
236				 MMC35240_CTRL1_BW_MASK,
237				 data->res << MMC35240_CTRL1_BW_SHIFT);
238	if (ret < 0)
239		return ret;
240
241	ret = regmap_bulk_read(data->regmap, MMC35240_OTP_START_ADDR,
242			       otp_data, sizeof(otp_data));
243	if (ret < 0)
244		return ret;
245
246	y_convert = MMC35240_OTP_CONVERT_Y(((otp_data[1] & 0x03) << 4) |
247					   (otp_data[2] >> 4));
248	z_convert = MMC35240_OTP_CONVERT_Z(otp_data[3] & 0x3f);
249
250	data->axis_coef[0] = MMC35240_X_COEFF(1);
251	data->axis_coef[1] = MMC35240_Y_COEFF(y_convert);
252	data->axis_coef[2] = MMC35240_Z_COEFF(z_convert);
253
254	data->axis_scale[0] = 1;
255	data->axis_scale[1] = 1000;
256	data->axis_scale[2] = 10000;
257
258	return 0;
259}
260
261static int mmc35240_take_measurement(struct mmc35240_data *data)
262{
263	int ret, tries = 100;
264	unsigned int reg_status;
265
266	ret = regmap_write(data->regmap, MMC35240_REG_CTRL0,
267			   MMC35240_CTRL0_TM_BIT);
268	if (ret < 0)
269		return ret;
270
271	while (tries-- > 0) {
272		ret = regmap_read(data->regmap, MMC35240_REG_STATUS,
273				  &reg_status);
274		if (ret < 0)
275			return ret;
276		if (reg_status & MMC35240_STATUS_MEAS_DONE_BIT)
277			break;
278		/* minimum wait time to complete measurement is 10 ms */
279		usleep_range(10000, 11000);
280	}
281
282	if (tries < 0) {
283		dev_err(&data->client->dev, "data not ready\n");
284		return -EIO;
285	}
286
287	return 0;
288}
289
290static int mmc35240_read_measurement(struct mmc35240_data *data, __le16 buf[3])
291{
292	int ret;
293
294	ret = mmc35240_take_measurement(data);
295	if (ret < 0)
296		return ret;
297
298	return regmap_bulk_read(data->regmap, MMC35240_REG_XOUT_L, buf,
299				3 * sizeof(__le16));
300}
301
302/**
303 * mmc35240_raw_to_mgauss - convert raw readings to milli gauss. Also apply
304 *			    compensation for output value.
305 *
306 * @data: device private data
307 * @index: axis index for which we want the conversion
308 * @buf: raw data to be converted, 2 bytes in little endian format
309 * @val: compensated output reading (unit is milli gauss)
310 *
311 * Returns: 0 in case of success, -EINVAL when @index is not valid
312 */
313static int mmc35240_raw_to_mgauss(struct mmc35240_data *data, int index,
314				  __le16 buf[], int *val)
315{
316	int raw[3];
317	int sens[3];
318	int nfo;
319
320	raw[AXIS_X] = le16_to_cpu(buf[AXIS_X]);
321	raw[AXIS_Y] = le16_to_cpu(buf[AXIS_Y]);
322	raw[AXIS_Z] = le16_to_cpu(buf[AXIS_Z]);
323
324	sens[AXIS_X] = mmc35240_props_table[data->res].sens[AXIS_X];
325	sens[AXIS_Y] = mmc35240_props_table[data->res].sens[AXIS_Y];
326	sens[AXIS_Z] = mmc35240_props_table[data->res].sens[AXIS_Z];
327
328	nfo = mmc35240_props_table[data->res].nfo;
329
330	switch (index) {
331	case AXIS_X:
332		*val = (raw[AXIS_X] - nfo) * 1000 / sens[AXIS_X];
333		break;
334	case AXIS_Y:
335		*val = (raw[AXIS_Y] - nfo) * 1000 / sens[AXIS_Y] -
336			(raw[AXIS_Z] - nfo)  * 1000 / sens[AXIS_Z];
337		break;
338	case AXIS_Z:
339		*val = (raw[AXIS_Y] - nfo) * 1000 / sens[AXIS_Y] +
340			(raw[AXIS_Z] - nfo) * 1000 / sens[AXIS_Z];
341		break;
342	default:
343		return -EINVAL;
344	}
345	/* apply OTP compensation */
346	*val = (*val) * data->axis_coef[index] / data->axis_scale[index];
347
348	return 0;
349}
350
351static int mmc35240_read_raw(struct iio_dev *indio_dev,
352			     struct iio_chan_spec const *chan, int *val,
353			     int *val2, long mask)
354{
355	struct mmc35240_data *data = iio_priv(indio_dev);
356	int ret, i;
357	unsigned int reg;
358	__le16 buf[3];
359
360	switch (mask) {
361	case IIO_CHAN_INFO_RAW:
362		mutex_lock(&data->mutex);
363		ret = mmc35240_read_measurement(data, buf);
364		mutex_unlock(&data->mutex);
365		if (ret < 0)
366			return ret;
367		ret = mmc35240_raw_to_mgauss(data, chan->address, buf, val);
368		if (ret < 0)
369			return ret;
370		return IIO_VAL_INT;
371	case IIO_CHAN_INFO_SCALE:
372		*val = 0;
373		*val2 = 1000;
374		return IIO_VAL_INT_PLUS_MICRO;
375	case IIO_CHAN_INFO_SAMP_FREQ:
376		mutex_lock(&data->mutex);
377		ret = regmap_read(data->regmap, MMC35240_REG_CTRL1, &reg);
378		mutex_unlock(&data->mutex);
379		if (ret < 0)
380			return ret;
381
382		i = (reg & MMC35240_CTRL1_BW_MASK) >> MMC35240_CTRL1_BW_SHIFT;
383		if (i < 0 || i >= ARRAY_SIZE(mmc35240_samp_freq))
384			return -EINVAL;
385
386		*val = mmc35240_samp_freq[i].val;
387		*val2 = mmc35240_samp_freq[i].val2;
388		return IIO_VAL_INT_PLUS_MICRO;
389	default:
390		return -EINVAL;
391	}
392}
393
394static int mmc35240_write_raw(struct iio_dev *indio_dev,
395			      struct iio_chan_spec const *chan, int val,
396			      int val2, long mask)
397{
398	struct mmc35240_data *data = iio_priv(indio_dev);
399	int i, ret;
400
401	switch (mask) {
402	case IIO_CHAN_INFO_SAMP_FREQ:
403		i = mmc35240_get_samp_freq_index(data, val, val2);
404		if (i < 0)
405			return -EINVAL;
406		mutex_lock(&data->mutex);
407		ret = regmap_update_bits(data->regmap, MMC35240_REG_CTRL1,
408					 MMC35240_CTRL1_BW_MASK,
409					 i << MMC35240_CTRL1_BW_SHIFT);
410		mutex_unlock(&data->mutex);
411		return ret;
412	default:
413		return -EINVAL;
414	}
415}
416
417static const struct iio_info mmc35240_info = {
418	.read_raw	= mmc35240_read_raw,
419	.write_raw	= mmc35240_write_raw,
420	.attrs		= &mmc35240_attribute_group,
421};
422
423static bool mmc35240_is_writeable_reg(struct device *dev, unsigned int reg)
424{
425	switch (reg) {
426	case MMC35240_REG_CTRL0:
427	case MMC35240_REG_CTRL1:
428		return true;
429	default:
430		return false;
431	}
432}
433
434static bool mmc35240_is_readable_reg(struct device *dev, unsigned int reg)
435{
436	switch (reg) {
437	case MMC35240_REG_XOUT_L:
438	case MMC35240_REG_XOUT_H:
439	case MMC35240_REG_YOUT_L:
440	case MMC35240_REG_YOUT_H:
441	case MMC35240_REG_ZOUT_L:
442	case MMC35240_REG_ZOUT_H:
443	case MMC35240_REG_STATUS:
444	case MMC35240_REG_ID:
445		return true;
446	default:
447		return false;
448	}
449}
450
451static bool mmc35240_is_volatile_reg(struct device *dev, unsigned int reg)
452{
453	switch (reg) {
454	case MMC35240_REG_CTRL0:
455	case MMC35240_REG_CTRL1:
456		return false;
457	default:
458		return true;
459	}
460}
461
462static const struct reg_default mmc35240_reg_defaults[] = {
463	{ MMC35240_REG_CTRL0,  0x00 },
464	{ MMC35240_REG_CTRL1,  0x00 },
465};
466
467static const struct regmap_config mmc35240_regmap_config = {
468	.name = MMC35240_REGMAP_NAME,
469
470	.reg_bits = 8,
471	.val_bits = 8,
472
473	.max_register = MMC35240_REG_ID,
474	.cache_type = REGCACHE_FLAT,
475
476	.writeable_reg = mmc35240_is_writeable_reg,
477	.readable_reg = mmc35240_is_readable_reg,
478	.volatile_reg = mmc35240_is_volatile_reg,
479
480	.reg_defaults = mmc35240_reg_defaults,
481	.num_reg_defaults = ARRAY_SIZE(mmc35240_reg_defaults),
482};
483
484static int mmc35240_probe(struct i2c_client *client)
485{
486	struct mmc35240_data *data;
487	struct iio_dev *indio_dev;
488	struct regmap *regmap;
489	int ret;
490
491	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
492	if (!indio_dev)
493		return -ENOMEM;
494
495	regmap = devm_regmap_init_i2c(client, &mmc35240_regmap_config);
496	if (IS_ERR(regmap)) {
497		dev_err(&client->dev, "regmap initialization failed\n");
498		return PTR_ERR(regmap);
499	}
500
501	data = iio_priv(indio_dev);
502	i2c_set_clientdata(client, indio_dev);
503	data->client = client;
504	data->regmap = regmap;
505	data->res = MMC35240_16_BITS_SLOW;
506
507	mutex_init(&data->mutex);
508
509	indio_dev->info = &mmc35240_info;
510	indio_dev->name = MMC35240_DRV_NAME;
511	indio_dev->channels = mmc35240_channels;
512	indio_dev->num_channels = ARRAY_SIZE(mmc35240_channels);
513	indio_dev->modes = INDIO_DIRECT_MODE;
514
515	ret = mmc35240_init(data);
516	if (ret < 0) {
517		dev_err(&client->dev, "mmc35240 chip init failed\n");
518		return ret;
519	}
520	return devm_iio_device_register(&client->dev, indio_dev);
521}
522
523static int mmc35240_suspend(struct device *dev)
524{
525	struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
526	struct mmc35240_data *data = iio_priv(indio_dev);
527
528	regcache_cache_only(data->regmap, true);
529
530	return 0;
531}
532
533static int mmc35240_resume(struct device *dev)
534{
535	struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
536	struct mmc35240_data *data = iio_priv(indio_dev);
537	int ret;
538
539	regcache_mark_dirty(data->regmap);
540	ret = regcache_sync_region(data->regmap, MMC35240_REG_CTRL0,
541				   MMC35240_REG_CTRL1);
542	if (ret < 0)
543		dev_err(dev, "Failed to restore control registers\n");
544
545	regcache_cache_only(data->regmap, false);
546
547	return 0;
548}
549
550static DEFINE_SIMPLE_DEV_PM_OPS(mmc35240_pm_ops, mmc35240_suspend,
551				mmc35240_resume);
552
553static const struct of_device_id mmc35240_of_match[] = {
554	{ .compatible = "memsic,mmc35240", },
555	{ }
556};
557MODULE_DEVICE_TABLE(of, mmc35240_of_match);
558
559static const struct acpi_device_id mmc35240_acpi_match[] = {
560	{"MMC35240", 0},
561	{ },
562};
563MODULE_DEVICE_TABLE(acpi, mmc35240_acpi_match);
564
565static const struct i2c_device_id mmc35240_id[] = {
566	{"mmc35240", 0},
567	{}
568};
569MODULE_DEVICE_TABLE(i2c, mmc35240_id);
570
571static struct i2c_driver mmc35240_driver = {
572	.driver = {
573		.name = MMC35240_DRV_NAME,
574		.of_match_table = mmc35240_of_match,
575		.pm = pm_sleep_ptr(&mmc35240_pm_ops),
576		.acpi_match_table = ACPI_PTR(mmc35240_acpi_match),
577	},
578	.probe		= mmc35240_probe,
579	.id_table	= mmc35240_id,
580};
581
582module_i2c_driver(mmc35240_driver);
583
584MODULE_AUTHOR("Daniel Baluta <daniel.baluta@intel.com>");
585MODULE_DESCRIPTION("MEMSIC MMC35240 magnetic sensor driver");
586MODULE_LICENSE("GPL v2");
587