mmc35240.c

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