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
82 enum 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
89 enum mmc35240_axis {
90 AXIS_X = 0,
91 AXIS_Y,
92 AXIS_Z,
93 };
94
95 static 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
121 struct 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
132 static const struct {
133 int val;
134 int val2;
135 } mmc35240_samp_freq[] = { {1, 500000},
136 {13, 0},
137 {25, 0},
138 {50, 0} };
139
140 static 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
152 static const struct iio_chan_spec mmc35240_channels[] = {
153 MMC35240_CHANNEL(X),
154 MMC35240_CHANNEL(Y),
155 MMC35240_CHANNEL(Z),
156 };
157
158 static struct attribute *mmc35240_attributes[] = {
159 &iio_const_attr_sampling_frequency_available.dev_attr.attr,
160 NULL
161 };
162
163 static const struct attribute_group mmc35240_attribute_group = {
164 .attrs = mmc35240_attributes,
165 };
166
mmc35240_get_samp_freq_index(struct mmc35240_data * data,int val,int val2)167 static 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
mmc35240_hw_set(struct mmc35240_data * data,bool set)179 static 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
mmc35240_init(struct mmc35240_data * data)203 static 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, ®_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
mmc35240_take_measurement(struct mmc35240_data * data)258 static 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 ®_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
mmc35240_read_measurement(struct mmc35240_data * data,__le16 buf[3])287 static 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 */
mmc35240_raw_to_mgauss(struct mmc35240_data * data,int index,__le16 buf[],int * val)310 static 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
mmc35240_read_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int * val,int * val2,long mask)348 static 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, ®);
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
mmc35240_write_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int val,int val2,long mask)391 static 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
414 static 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
mmc35240_is_writeable_reg(struct device * dev,unsigned int reg)420 static 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
mmc35240_is_readable_reg(struct device * dev,unsigned int reg)431 static 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
mmc35240_is_volatile_reg(struct device * dev,unsigned int reg)448 static 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
459 static const struct reg_default mmc35240_reg_defaults[] = {
460 { MMC35240_REG_CTRL0, 0x00 },
461 { MMC35240_REG_CTRL1, 0x00 },
462 };
463
464 static 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
mmc35240_probe(struct i2c_client * client)481 static 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
mmc35240_suspend(struct device * dev)520 static 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
mmc35240_resume(struct device * dev)530 static 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
547 static DEFINE_SIMPLE_DEV_PM_OPS(mmc35240_pm_ops, mmc35240_suspend,
548 mmc35240_resume);
549
550 static const struct of_device_id mmc35240_of_match[] = {
551 { .compatible = "memsic,mmc35240", },
552 { }
553 };
554 MODULE_DEVICE_TABLE(of, mmc35240_of_match);
555
556 static const struct acpi_device_id mmc35240_acpi_match[] = {
557 {"MMC35240", 0},
558 { }
559 };
560 MODULE_DEVICE_TABLE(acpi, mmc35240_acpi_match);
561
562 static const struct i2c_device_id mmc35240_id[] = {
563 { "mmc35240" },
564 { }
565 };
566 MODULE_DEVICE_TABLE(i2c, mmc35240_id);
567
568 static 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
579 module_i2c_driver(mmc35240_driver);
580
581 MODULE_AUTHOR("Daniel Baluta <daniel.baluta@intel.com>");
582 MODULE_DESCRIPTION("MEMSIC MMC35240 magnetic sensor driver");
583 MODULE_LICENSE("GPL v2");
584