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 #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
83 enum 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
90 enum mmc35240_axis {
91 AXIS_X = 0,
92 AXIS_Y,
93 AXIS_Z,
94 };
95
96 static 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
122 struct 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
133 static const struct {
134 int val;
135 int val2;
136 } mmc35240_samp_freq[] = { {1, 500000},
137 {13, 0},
138 {25, 0},
139 {50, 0} };
140
141 static 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
153 static const struct iio_chan_spec mmc35240_channels[] = {
154 MMC35240_CHANNEL(X),
155 MMC35240_CHANNEL(Y),
156 MMC35240_CHANNEL(Z),
157 };
158
159 static struct attribute *mmc35240_attributes[] = {
160 &iio_const_attr_sampling_frequency_available.dev_attr.attr,
161 NULL
162 };
163
164 static const struct attribute_group mmc35240_attribute_group = {
165 .attrs = mmc35240_attributes,
166 };
167
mmc35240_get_samp_freq_index(struct mmc35240_data * data,int val,int val2)168 static 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
mmc35240_hw_set(struct mmc35240_data * data,bool set)180 static 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_set_bits(data->regmap, MMC35240_REG_CTRL0,
190 MMC35240_CTRL0_REFILL_BIT);
191 if (ret < 0)
192 return ret;
193 usleep_range(MMC35240_WAIT_CHARGE_PUMP, MMC35240_WAIT_CHARGE_PUMP + 1);
194
195 if (set)
196 coil_bit = MMC35240_CTRL0_SET_BIT;
197 else
198 coil_bit = MMC35240_CTRL0_RESET_BIT;
199
200 return regmap_set_bits(data->regmap, MMC35240_REG_CTRL0, coil_bit);
201
202 }
203
mmc35240_init(struct mmc35240_data * data)204 static int mmc35240_init(struct mmc35240_data *data)
205 {
206 int ret, y_convert, z_convert;
207 unsigned int reg_id;
208 u8 otp_data[6];
209
210 ret = regmap_read(data->regmap, MMC35240_REG_ID, ®_id);
211 if (ret < 0) {
212 dev_err(&data->client->dev, "Error reading product id\n");
213 return ret;
214 }
215
216 dev_dbg(&data->client->dev, "MMC35240 chip id %x\n", reg_id);
217
218 /*
219 * make sure we restore sensor characteristics, by doing
220 * a SET/RESET sequence, the axis polarity being naturally
221 * aligned after RESET
222 */
223 ret = mmc35240_hw_set(data, true);
224 if (ret < 0)
225 return ret;
226 usleep_range(MMC35240_WAIT_SET_RESET, MMC35240_WAIT_SET_RESET + 1);
227
228 ret = mmc35240_hw_set(data, false);
229 if (ret < 0)
230 return ret;
231
232 /* set default sampling frequency */
233 ret = regmap_update_bits(data->regmap, MMC35240_REG_CTRL1,
234 MMC35240_CTRL1_BW_MASK,
235 data->res << MMC35240_CTRL1_BW_SHIFT);
236 if (ret < 0)
237 return ret;
238
239 ret = regmap_bulk_read(data->regmap, MMC35240_OTP_START_ADDR,
240 otp_data, sizeof(otp_data));
241 if (ret < 0)
242 return ret;
243
244 y_convert = MMC35240_OTP_CONVERT_Y(((otp_data[1] & 0x03) << 4) |
245 (otp_data[2] >> 4));
246 z_convert = MMC35240_OTP_CONVERT_Z(otp_data[3] & 0x3f);
247
248 data->axis_coef[0] = MMC35240_X_COEFF(1);
249 data->axis_coef[1] = MMC35240_Y_COEFF(y_convert);
250 data->axis_coef[2] = MMC35240_Z_COEFF(z_convert);
251
252 data->axis_scale[0] = 1;
253 data->axis_scale[1] = 1000;
254 data->axis_scale[2] = 10000;
255
256 return 0;
257 }
258
mmc35240_take_measurement(struct mmc35240_data * data)259 static int mmc35240_take_measurement(struct mmc35240_data *data)
260 {
261 int ret, tries = 100;
262 unsigned int reg_status;
263
264 ret = regmap_write(data->regmap, MMC35240_REG_CTRL0,
265 MMC35240_CTRL0_TM_BIT);
266 if (ret < 0)
267 return ret;
268
269 while (tries-- > 0) {
270 ret = regmap_read(data->regmap, MMC35240_REG_STATUS,
271 ®_status);
272 if (ret < 0)
273 return ret;
274 if (reg_status & MMC35240_STATUS_MEAS_DONE_BIT)
275 break;
276 /* minimum wait time to complete measurement is 10 ms */
277 usleep_range(10000, 11000);
278 }
279
280 if (tries < 0) {
281 dev_err(&data->client->dev, "data not ready\n");
282 return -EIO;
283 }
284
285 return 0;
286 }
287
mmc35240_read_measurement(struct mmc35240_data * data,__le16 buf[3])288 static int mmc35240_read_measurement(struct mmc35240_data *data, __le16 buf[3])
289 {
290 int ret;
291
292 ret = mmc35240_take_measurement(data);
293 if (ret < 0)
294 return ret;
295
296 return regmap_bulk_read(data->regmap, MMC35240_REG_XOUT_L, buf,
297 3 * sizeof(__le16));
298 }
299
300 /**
301 * mmc35240_raw_to_mgauss - convert raw readings to milli gauss. Also apply
302 * compensation for output value.
303 *
304 * @data: device private data
305 * @index: axis index for which we want the conversion
306 * @buf: raw data to be converted, 2 bytes in little endian format
307 * @val: compensated output reading (unit is milli gauss)
308 *
309 * Returns: 0 in case of success, -EINVAL when @index is not valid
310 */
mmc35240_raw_to_mgauss(struct mmc35240_data * data,int index,__le16 buf[],int * val)311 static int mmc35240_raw_to_mgauss(struct mmc35240_data *data, int index,
312 __le16 buf[], int *val)
313 {
314 int raw[3];
315 int sens[3];
316 int nfo;
317
318 raw[AXIS_X] = le16_to_cpu(buf[AXIS_X]);
319 raw[AXIS_Y] = le16_to_cpu(buf[AXIS_Y]);
320 raw[AXIS_Z] = le16_to_cpu(buf[AXIS_Z]);
321
322 sens[AXIS_X] = mmc35240_props_table[data->res].sens[AXIS_X];
323 sens[AXIS_Y] = mmc35240_props_table[data->res].sens[AXIS_Y];
324 sens[AXIS_Z] = mmc35240_props_table[data->res].sens[AXIS_Z];
325
326 nfo = mmc35240_props_table[data->res].nfo;
327
328 switch (index) {
329 case AXIS_X:
330 *val = (raw[AXIS_X] - nfo) * 1000 / sens[AXIS_X];
331 break;
332 case AXIS_Y:
333 *val = (raw[AXIS_Y] - nfo) * 1000 / sens[AXIS_Y] -
334 (raw[AXIS_Z] - nfo) * 1000 / sens[AXIS_Z];
335 break;
336 case AXIS_Z:
337 *val = (raw[AXIS_Y] - nfo) * 1000 / sens[AXIS_Y] +
338 (raw[AXIS_Z] - nfo) * 1000 / sens[AXIS_Z];
339 break;
340 default:
341 return -EINVAL;
342 }
343 /* apply OTP compensation */
344 *val = (*val) * data->axis_coef[index] / data->axis_scale[index];
345
346 return 0;
347 }
348
mmc35240_read_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int * val,int * val2,long mask)349 static int mmc35240_read_raw(struct iio_dev *indio_dev,
350 struct iio_chan_spec const *chan, int *val,
351 int *val2, long mask)
352 {
353 struct mmc35240_data *data = iio_priv(indio_dev);
354 int ret, i;
355 unsigned int reg;
356 __le16 buf[3];
357
358 switch (mask) {
359 case IIO_CHAN_INFO_RAW:
360 mutex_lock(&data->mutex);
361 ret = mmc35240_read_measurement(data, buf);
362 mutex_unlock(&data->mutex);
363 if (ret < 0)
364 return ret;
365 ret = mmc35240_raw_to_mgauss(data, chan->address, buf, val);
366 if (ret < 0)
367 return ret;
368 return IIO_VAL_INT;
369 case IIO_CHAN_INFO_SCALE:
370 *val = 0;
371 *val2 = 1000;
372 return IIO_VAL_INT_PLUS_MICRO;
373 case IIO_CHAN_INFO_SAMP_FREQ:
374 mutex_lock(&data->mutex);
375 ret = regmap_read(data->regmap, MMC35240_REG_CTRL1, ®);
376 mutex_unlock(&data->mutex);
377 if (ret < 0)
378 return ret;
379
380 i = (reg & MMC35240_CTRL1_BW_MASK) >> MMC35240_CTRL1_BW_SHIFT;
381 if (i < 0 || i >= ARRAY_SIZE(mmc35240_samp_freq))
382 return -EINVAL;
383
384 *val = mmc35240_samp_freq[i].val;
385 *val2 = mmc35240_samp_freq[i].val2;
386 return IIO_VAL_INT_PLUS_MICRO;
387 default:
388 return -EINVAL;
389 }
390 }
391
mmc35240_write_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int val,int val2,long mask)392 static int mmc35240_write_raw(struct iio_dev *indio_dev,
393 struct iio_chan_spec const *chan, int val,
394 int val2, long mask)
395 {
396 struct mmc35240_data *data = iio_priv(indio_dev);
397 int i, ret;
398
399 switch (mask) {
400 case IIO_CHAN_INFO_SAMP_FREQ:
401 i = mmc35240_get_samp_freq_index(data, val, val2);
402 if (i < 0)
403 return -EINVAL;
404 mutex_lock(&data->mutex);
405 ret = regmap_update_bits(data->regmap, MMC35240_REG_CTRL1,
406 MMC35240_CTRL1_BW_MASK,
407 i << MMC35240_CTRL1_BW_SHIFT);
408 mutex_unlock(&data->mutex);
409 return ret;
410 default:
411 return -EINVAL;
412 }
413 }
414
415 static const struct iio_info mmc35240_info = {
416 .read_raw = mmc35240_read_raw,
417 .write_raw = mmc35240_write_raw,
418 .attrs = &mmc35240_attribute_group,
419 };
420
mmc35240_is_writeable_reg(struct device * dev,unsigned int reg)421 static bool mmc35240_is_writeable_reg(struct device *dev, unsigned int reg)
422 {
423 switch (reg) {
424 case MMC35240_REG_CTRL0:
425 case MMC35240_REG_CTRL1:
426 return true;
427 default:
428 return false;
429 }
430 }
431
mmc35240_is_readable_reg(struct device * dev,unsigned int reg)432 static bool mmc35240_is_readable_reg(struct device *dev, unsigned int reg)
433 {
434 switch (reg) {
435 case MMC35240_REG_XOUT_L:
436 case MMC35240_REG_XOUT_H:
437 case MMC35240_REG_YOUT_L:
438 case MMC35240_REG_YOUT_H:
439 case MMC35240_REG_ZOUT_L:
440 case MMC35240_REG_ZOUT_H:
441 case MMC35240_REG_STATUS:
442 case MMC35240_REG_ID:
443 return true;
444 default:
445 return false;
446 }
447 }
448
mmc35240_is_volatile_reg(struct device * dev,unsigned int reg)449 static bool mmc35240_is_volatile_reg(struct device *dev, unsigned int reg)
450 {
451 switch (reg) {
452 case MMC35240_REG_CTRL0:
453 case MMC35240_REG_CTRL1:
454 return false;
455 default:
456 return true;
457 }
458 }
459
460 static const struct reg_default mmc35240_reg_defaults[] = {
461 { MMC35240_REG_CTRL0, 0x00 },
462 { MMC35240_REG_CTRL1, 0x00 },
463 };
464
465 static const struct regmap_config mmc35240_regmap_config = {
466 .name = MMC35240_REGMAP_NAME,
467
468 .reg_bits = 8,
469 .val_bits = 8,
470
471 .max_register = MMC35240_REG_ID,
472 .cache_type = REGCACHE_FLAT,
473
474 .writeable_reg = mmc35240_is_writeable_reg,
475 .readable_reg = mmc35240_is_readable_reg,
476 .volatile_reg = mmc35240_is_volatile_reg,
477
478 .reg_defaults = mmc35240_reg_defaults,
479 .num_reg_defaults = ARRAY_SIZE(mmc35240_reg_defaults),
480 };
481
mmc35240_probe(struct i2c_client * client)482 static int mmc35240_probe(struct i2c_client *client)
483 {
484 struct mmc35240_data *data;
485 struct iio_dev *indio_dev;
486 struct regmap *regmap;
487 int ret;
488
489 indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
490 if (!indio_dev)
491 return -ENOMEM;
492
493 regmap = devm_regmap_init_i2c(client, &mmc35240_regmap_config);
494 if (IS_ERR(regmap)) {
495 dev_err(&client->dev, "regmap initialization failed\n");
496 return PTR_ERR(regmap);
497 }
498
499 data = iio_priv(indio_dev);
500 i2c_set_clientdata(client, indio_dev);
501 data->client = client;
502 data->regmap = regmap;
503 data->res = MMC35240_16_BITS_SLOW;
504
505 mutex_init(&data->mutex);
506
507 indio_dev->info = &mmc35240_info;
508 indio_dev->name = MMC35240_DRV_NAME;
509 indio_dev->channels = mmc35240_channels;
510 indio_dev->num_channels = ARRAY_SIZE(mmc35240_channels);
511 indio_dev->modes = INDIO_DIRECT_MODE;
512
513 ret = mmc35240_init(data);
514 if (ret < 0) {
515 dev_err(&client->dev, "mmc35240 chip init failed\n");
516 return ret;
517 }
518 return devm_iio_device_register(&client->dev, indio_dev);
519 }
520
mmc35240_suspend(struct device * dev)521 static int mmc35240_suspend(struct device *dev)
522 {
523 struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
524 struct mmc35240_data *data = iio_priv(indio_dev);
525
526 regcache_cache_only(data->regmap, true);
527
528 return 0;
529 }
530
mmc35240_resume(struct device * dev)531 static int mmc35240_resume(struct device *dev)
532 {
533 struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
534 struct mmc35240_data *data = iio_priv(indio_dev);
535 int ret;
536
537 regcache_mark_dirty(data->regmap);
538 ret = regcache_sync_region(data->regmap, MMC35240_REG_CTRL0,
539 MMC35240_REG_CTRL1);
540 if (ret < 0)
541 dev_err(dev, "Failed to restore control registers\n");
542
543 regcache_cache_only(data->regmap, false);
544
545 return 0;
546 }
547
548 static DEFINE_SIMPLE_DEV_PM_OPS(mmc35240_pm_ops, mmc35240_suspend,
549 mmc35240_resume);
550
551 static const struct of_device_id mmc35240_of_match[] = {
552 { .compatible = "memsic,mmc35240", },
553 { }
554 };
555 MODULE_DEVICE_TABLE(of, mmc35240_of_match);
556
557 static const struct acpi_device_id mmc35240_acpi_match[] = {
558 {"MMC35240", 0},
559 { },
560 };
561 MODULE_DEVICE_TABLE(acpi, mmc35240_acpi_match);
562
563 static const struct i2c_device_id mmc35240_id[] = {
564 { "mmc35240" },
565 {}
566 };
567 MODULE_DEVICE_TABLE(i2c, mmc35240_id);
568
569 static struct i2c_driver mmc35240_driver = {
570 .driver = {
571 .name = MMC35240_DRV_NAME,
572 .of_match_table = mmc35240_of_match,
573 .pm = pm_sleep_ptr(&mmc35240_pm_ops),
574 .acpi_match_table = mmc35240_acpi_match,
575 },
576 .probe = mmc35240_probe,
577 .id_table = mmc35240_id,
578 };
579
580 module_i2c_driver(mmc35240_driver);
581
582 MODULE_AUTHOR("Daniel Baluta <daniel.baluta@intel.com>");
583 MODULE_DESCRIPTION("MEMSIC MMC35240 magnetic sensor driver");
584 MODULE_LICENSE("GPL v2");
585