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