drivers/iio/magnetometer/rm3100-core.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * PNI RM3100 3-axis geomagnetic sensor driver core.
   4  *
   5  * Copyright (C) 2018 Song Qiang <[email protected]>
   6  *
   7  * User Manual available at
   8  * <https://www.pnicorp.com/download/rm3100-user-manual/>
   9  *
  10  * TODO: event generation, pm.
  11  */
  12
  13 #include <linux/delay.h>
  14 #include <linux/interrupt.h>
  15 #include <linux/module.h>
  16 #include <linux/slab.h>
  17
  18 #include <linux/iio/buffer.h>
  19 #include <linux/iio/iio.h>
  20 #include <linux/iio/sysfs.h>
  21 #include <linux/iio/trigger.h>
  22 #include <linux/iio/triggered_buffer.h>
  23 #include <linux/iio/trigger_consumer.h>
  24
  25 #include <linux/unaligned.h>
  26
  27 #include "rm3100.h"
  28
  29 /* Cycle Count Registers. */
  30 #define RM3100_REG_CC_X                 0x05
  31 #define RM3100_REG_CC_Y                 0x07
  32 #define RM3100_REG_CC_Z                 0x09
  33
  34 /* Poll Measurement Mode register. */
  35 #define RM3100_REG_POLL                 0x00
  36 #define         RM3100_POLL_X           BIT(4)
  37 #define         RM3100_POLL_Y           BIT(5)
  38 #define         RM3100_POLL_Z           BIT(6)
  39
  40 /* Continuous Measurement Mode register. */
  41 #define RM3100_REG_CMM                  0x01
  42 #define         RM3100_CMM_START        BIT(0)
  43 #define         RM3100_CMM_X            BIT(4)
  44 #define         RM3100_CMM_Y            BIT(5)
  45 #define         RM3100_CMM_Z            BIT(6)
  46
  47 /* TiMe Rate Configuration register. */
  48 #define RM3100_REG_TMRC                 0x0B
  49 #define RM3100_TMRC_OFFSET              0x92
  50
  51 /* Result Status register. */
  52 #define RM3100_REG_STATUS               0x34
  53 #define         RM3100_STATUS_DRDY      BIT(7)
  54
  55 /* Measurement result registers. */
  56 #define RM3100_REG_MX2                  0x24
  57 #define RM3100_REG_MY2                  0x27
  58 #define RM3100_REG_MZ2                  0x2a
  59
  60 #define RM3100_W_REG_START              RM3100_REG_POLL
  61 #define RM3100_W_REG_END                RM3100_REG_TMRC
  62 #define RM3100_R_REG_START              RM3100_REG_POLL
  63 #define RM3100_R_REG_END                RM3100_REG_STATUS
  64 #define RM3100_V_REG_START              RM3100_REG_POLL
  65 #define RM3100_V_REG_END                RM3100_REG_STATUS
  66
  67 /*
  68  * This is computed by hand, is the sum of channel storage bits and padding
  69  * bits, which is 4+4+4+12=24 in here.
  70  */
  71 #define RM3100_SCAN_BYTES               24
  72
  73 #define RM3100_CMM_AXIS_SHIFT           4
  74
  75 struct rm3100_data {
  76         struct regmap *regmap;
  77         struct completion measuring_done;
  78         bool use_interrupt;
  79         int conversion_time;
  80         int scale;
  81         /* Ensure naturally aligned timestamp */
  82         u8 buffer[RM3100_SCAN_BYTES] __aligned(8);
  83         struct iio_trigger *drdy_trig;
  84
  85         /*
  86          * This lock is for protecting the consistency of series of i2c
  87          * operations, that is, to make sure a measurement process will
  88          * not be interrupted by a set frequency operation, which should
  89          * be taken where a series of i2c operation starts, released where
  90          * the operation ends.
  91          */
  92         struct mutex lock;
  93 };
  94
  95 static const struct regmap_range rm3100_readable_ranges[] = {
  96         regmap_reg_range(RM3100_R_REG_START, RM3100_R_REG_END),
  97 };
  98
  99 const struct regmap_access_table rm3100_readable_table = {
 100         .yes_ranges = rm3100_readable_ranges,
 101         .n_yes_ranges = ARRAY_SIZE(rm3100_readable_ranges),
 102 };
 103 EXPORT_SYMBOL_NS_GPL(rm3100_readable_table, "IIO_RM3100");
 104
 105 static const struct regmap_range rm3100_writable_ranges[] = {
 106         regmap_reg_range(RM3100_W_REG_START, RM3100_W_REG_END),
 107 };
 108
 109 const struct regmap_access_table rm3100_writable_table = {
 110         .yes_ranges = rm3100_writable_ranges,
 111         .n_yes_ranges = ARRAY_SIZE(rm3100_writable_ranges),
 112 };
 113 EXPORT_SYMBOL_NS_GPL(rm3100_writable_table, "IIO_RM3100");
 114
 115 static const struct regmap_range rm3100_volatile_ranges[] = {
 116         regmap_reg_range(RM3100_V_REG_START, RM3100_V_REG_END),
 117 };
 118
 119 const struct regmap_access_table rm3100_volatile_table = {
 120         .yes_ranges = rm3100_volatile_ranges,
 121         .n_yes_ranges = ARRAY_SIZE(rm3100_volatile_ranges),
 122 };
 123 EXPORT_SYMBOL_NS_GPL(rm3100_volatile_table, "IIO_RM3100");
 124
 125 static irqreturn_t rm3100_thread_fn(int irq, void *d)
 126 {
 127         struct iio_dev *indio_dev = d;
 128         struct rm3100_data *data = iio_priv(indio_dev);
 129
 130         /*
 131          * Write operation to any register or read operation
 132          * to first byte of results will clear the interrupt.
 133          */
 134         regmap_write(data->regmap, RM3100_REG_POLL, 0);
 135
 136         return IRQ_HANDLED;
 137 }
 138
 139 static irqreturn_t rm3100_irq_handler(int irq, void *d)
 140 {
 141         struct iio_dev *indio_dev = d;
 142         struct rm3100_data *data = iio_priv(indio_dev);
 143
 144         if (!iio_buffer_enabled(indio_dev))
 145                 complete(&data->measuring_done);
 146         else
 147                 iio_trigger_poll(data->drdy_trig);
 148
 149         return IRQ_WAKE_THREAD;
 150 }
 151
 152 static int rm3100_wait_measurement(struct rm3100_data *data)
 153 {
 154         struct regmap *regmap = data->regmap;
 155         unsigned int val;
 156         int tries = 20;
 157         int ret;
 158
 159         /*
 160          * A read cycle of 400kbits i2c bus is about 20us, plus the time
 161          * used for scheduling, a read cycle of fast mode of this device
 162          * can reach 1.7ms, it may be possible for data to arrive just
 163          * after we check the RM3100_REG_STATUS. In this case, irq_handler is
 164          * called before measuring_done is reinitialized, it will wait
 165          * forever for data that has already been ready.
 166          * Reinitialize measuring_done before looking up makes sure we
 167          * will always capture interrupt no matter when it happens.
 168          */
 169         if (data->use_interrupt)
 170                 reinit_completion(&data->measuring_done);
 171
 172         ret = regmap_read(regmap, RM3100_REG_STATUS, &val);
 173         if (ret < 0)
 174                 return ret;
 175
 176         if ((val & RM3100_STATUS_DRDY) != RM3100_STATUS_DRDY) {
 177                 if (data->use_interrupt) {
 178                         ret = wait_for_completion_timeout(&data->measuring_done,
 179                                 msecs_to_jiffies(data->conversion_time));
 180                         if (!ret)
 181                                 return -ETIMEDOUT;
 182                 } else {
 183                         do {
 184                                 usleep_range(1000, 5000);
 185
 186                                 ret = regmap_read(regmap, RM3100_REG_STATUS,
 187                                                   &val);
 188                                 if (ret < 0)
 189                                         return ret;
 190
 191                                 if (val & RM3100_STATUS_DRDY)
 192                                         break;
 193                         } while (--tries);
 194                         if (!tries)
 195                                 return -ETIMEDOUT;
 196                 }
 197         }
 198         return 0;
 199 }
 200
 201 static int rm3100_read_mag(struct rm3100_data *data, int idx, int *val)
 202 {
 203         struct regmap *regmap = data->regmap;
 204         u8 buffer[3];
 205         int ret;
 206
 207         mutex_lock(&data->lock);
 208         ret = regmap_write(regmap, RM3100_REG_POLL, BIT(4 + idx));
 209         if (ret < 0)
 210                 goto unlock_return;
 211
 212         ret = rm3100_wait_measurement(data);
 213         if (ret < 0)
 214                 goto unlock_return;
 215
 216         ret = regmap_bulk_read(regmap, RM3100_REG_MX2 + 3 * idx, buffer, 3);
 217         if (ret < 0)
 218                 goto unlock_return;
 219         mutex_unlock(&data->lock);
 220
 221         *val = sign_extend32(get_unaligned_be24(&buffer[0]), 23);
 222
 223         return IIO_VAL_INT;
 224
 225 unlock_return:
 226         mutex_unlock(&data->lock);
 227         return ret;
 228 }
 229
 230 #define RM3100_CHANNEL(axis, idx)                                       \
 231         {                                                               \
 232                 .type = IIO_MAGN,                                       \
 233                 .modified = 1,                                          \
 234                 .channel2 = IIO_MOD_##axis,                             \
 235                 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),           \
 236                 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) |  \
 237                         BIT(IIO_CHAN_INFO_SAMP_FREQ),                   \
 238                 .scan_index = idx,                                      \
 239                 .scan_type = {                                          \
 240                         .sign = 's',                                    \
 241                         .realbits = 24,                                 \
 242                         .storagebits = 32,                              \
 243                         .shift = 8,                                     \
 244                         .endianness = IIO_BE,                           \
 245                 },                                                      \
 246         }
 247
 248 static const struct iio_chan_spec rm3100_channels[] = {
 249         RM3100_CHANNEL(X, 0),
 250         RM3100_CHANNEL(Y, 1),
 251         RM3100_CHANNEL(Z, 2),
 252         IIO_CHAN_SOFT_TIMESTAMP(3),
 253 };
 254
 255 static IIO_CONST_ATTR_SAMP_FREQ_AVAIL(
 256         "600 300 150 75 37 18 9 4.5 2.3 1.2 0.6 0.3 0.015 0.075"
 257 );
 258
 259 static struct attribute *rm3100_attributes[] = {
 260         &iio_const_attr_sampling_frequency_available.dev_attr.attr,
 261         NULL,
 262 };
 263
 264 static const struct attribute_group rm3100_attribute_group = {
 265         .attrs = rm3100_attributes,
 266 };
 267
 268 #define RM3100_SAMP_NUM                 14
 269
 270 /*
 271  * Frequency : rm3100_samp_rates[][0].rm3100_samp_rates[][1]Hz.
 272  * Time between reading: rm3100_sam_rates[][2]ms.
 273  * The first one is actually 1.7ms.
 274  */
 275 static const int rm3100_samp_rates[RM3100_SAMP_NUM][3] = {
 276         {600, 0, 2}, {300, 0, 3}, {150, 0, 7}, {75, 0, 13}, {37, 0, 27},
 277         {18, 0, 55}, {9, 0, 110}, {4, 500000, 220}, {2, 300000, 440},
 278         {1, 200000, 800}, {0, 600000, 1600}, {0, 300000, 3300},
 279         {0, 15000, 6700},  {0, 75000, 13000}
 280 };
 281
 282 static int rm3100_get_samp_freq(struct rm3100_data *data, int *val, int *val2)
 283 {
 284         unsigned int tmp;
 285         int ret;
 286
 287         mutex_lock(&data->lock);
 288         ret = regmap_read(data->regmap, RM3100_REG_TMRC, &tmp);
 289         mutex_unlock(&data->lock);
 290         if (ret < 0)
 291                 return ret;
 292         *val = rm3100_samp_rates[tmp - RM3100_TMRC_OFFSET][0];
 293         *val2 = rm3100_samp_rates[tmp - RM3100_TMRC_OFFSET][1];
 294
 295         return IIO_VAL_INT_PLUS_MICRO;
 296 }
 297
 298 static int rm3100_set_cycle_count(struct rm3100_data *data, int val)
 299 {
 300         int ret;
 301         u8 i;
 302
 303         for (i = 0; i < 3; i++) {
 304                 ret = regmap_write(data->regmap, RM3100_REG_CC_X + 2 * i, val);
 305                 if (ret < 0)
 306                         return ret;
 307         }
 308
 309         /*
 310          * The scale of this sensor depends on the cycle count value, these
 311          * three values are corresponding to the cycle count value 50, 100,
 312          * 200. scale = output / gain * 10^4.
 313          */
 314         switch (val) {
 315         case 50:
 316                 data->scale = 500;
 317                 break;
 318         case 100:
 319                 data->scale = 263;
 320                 break;
 321         /*
 322          * case 200:
 323          * This function will never be called by users' code, so here we
 324          * assume that it will never get a wrong parameter.
 325          */
 326         default:
 327                 data->scale = 133;
 328         }
 329
 330         return 0;
 331 }
 332
 333 static int rm3100_set_samp_freq(struct iio_dev *indio_dev, int val, int val2)
 334 {
 335         struct rm3100_data *data = iio_priv(indio_dev);
 336         struct regmap *regmap = data->regmap;
 337         unsigned int cycle_count;
 338         int ret;
 339         int i;
 340
 341         mutex_lock(&data->lock);
 342         /* All cycle count registers use the same value. */
 343         ret = regmap_read(regmap, RM3100_REG_CC_X, &cycle_count);
 344         if (ret < 0)
 345                 goto unlock_return;
 346
 347         for (i = 0; i < RM3100_SAMP_NUM; i++) {
 348                 if (val == rm3100_samp_rates[i][0] &&
 349                     val2 == rm3100_samp_rates[i][1])
 350                         break;
 351         }
 352         if (i == RM3100_SAMP_NUM) {
 353                 ret = -EINVAL;
 354                 goto unlock_return;
 355         }
 356
 357         ret = regmap_write(regmap, RM3100_REG_TMRC, i + RM3100_TMRC_OFFSET);
 358         if (ret < 0)
 359                 goto unlock_return;
 360
 361         /* Checking if cycle count registers need changing. */
 362         if (val == 600 && cycle_count == 200) {
 363                 ret = rm3100_set_cycle_count(data, 100);
 364                 if (ret < 0)
 365                         goto unlock_return;
 366         } else if (val != 600 && cycle_count == 100) {
 367                 ret = rm3100_set_cycle_count(data, 200);
 368                 if (ret < 0)
 369                         goto unlock_return;
 370         }
 371
 372         if (iio_buffer_enabled(indio_dev)) {
 373                 /* Writing TMRC registers requires CMM reset. */
 374                 ret = regmap_write(regmap, RM3100_REG_CMM, 0);
 375                 if (ret < 0)
 376                         goto unlock_return;
 377                 ret = regmap_write(data->regmap, RM3100_REG_CMM,
 378                         (*indio_dev->active_scan_mask & 0x7) <<
 379                         RM3100_CMM_AXIS_SHIFT | RM3100_CMM_START);
 380                 if (ret < 0)
 381                         goto unlock_return;
 382         }
 383         mutex_unlock(&data->lock);
 384
 385         data->conversion_time = rm3100_samp_rates[i][2] * 2;
 386         return 0;
 387
 388 unlock_return:
 389         mutex_unlock(&data->lock);
 390         return ret;
 391 }
 392
 393 static int rm3100_read_raw(struct iio_dev *indio_dev,
 394                            const struct iio_chan_spec *chan,
 395                            int *val, int *val2, long mask)
 396 {
 397         struct rm3100_data *data = iio_priv(indio_dev);
 398         int ret;
 399
 400         switch (mask) {
 401         case IIO_CHAN_INFO_RAW:
 402                 ret = iio_device_claim_direct_mode(indio_dev);
 403                 if (ret < 0)
 404                         return ret;
 405
 406                 ret = rm3100_read_mag(data, chan->scan_index, val);
 407                 iio_device_release_direct_mode(indio_dev);
 408
 409                 return ret;
 410         case IIO_CHAN_INFO_SCALE:
 411                 *val = 0;
 412                 *val2 = data->scale;
 413
 414                 return IIO_VAL_INT_PLUS_MICRO;
 415         case IIO_CHAN_INFO_SAMP_FREQ:
 416                 return rm3100_get_samp_freq(data, val, val2);
 417         default:
 418                 return -EINVAL;
 419         }
 420 }
 421
 422 static int rm3100_write_raw(struct iio_dev *indio_dev,
 423                             struct iio_chan_spec const *chan,
 424                             int val, int val2, long mask)
 425 {
 426         switch (mask) {
 427         case IIO_CHAN_INFO_SAMP_FREQ:
 428                 return rm3100_set_samp_freq(indio_dev, val, val2);
 429         default:
 430                 return -EINVAL;
 431         }
 432 }
 433
 434 static const struct iio_info rm3100_info = {
 435         .attrs = &rm3100_attribute_group,
 436         .read_raw = rm3100_read_raw,
 437         .write_raw = rm3100_write_raw,
 438 };
 439
 440 static int rm3100_buffer_preenable(struct iio_dev *indio_dev)
 441 {
 442         struct rm3100_data *data = iio_priv(indio_dev);
 443
 444         /* Starting channels enabled. */
 445         return regmap_write(data->regmap, RM3100_REG_CMM,
 446                 (*indio_dev->active_scan_mask & 0x7) << RM3100_CMM_AXIS_SHIFT |
 447                 RM3100_CMM_START);
 448 }
 449
 450 static int rm3100_buffer_postdisable(struct iio_dev *indio_dev)
 451 {
 452         struct rm3100_data *data = iio_priv(indio_dev);
 453
 454         return regmap_write(data->regmap, RM3100_REG_CMM, 0);
 455 }
 456
 457 static const struct iio_buffer_setup_ops rm3100_buffer_ops = {
 458         .preenable = rm3100_buffer_preenable,
 459         .postdisable = rm3100_buffer_postdisable,
 460 };
 461
 462 static irqreturn_t rm3100_trigger_handler(int irq, void *p)
 463 {
 464         struct iio_poll_func *pf = p;
 465         struct iio_dev *indio_dev = pf->indio_dev;
 466         unsigned long scan_mask = *indio_dev->active_scan_mask;
 467         unsigned int mask_len = iio_get_masklength(indio_dev);
 468         struct rm3100_data *data = iio_priv(indio_dev);
 469         struct regmap *regmap = data->regmap;
 470         int ret, i, bit;
 471
 472         mutex_lock(&data->lock);
 473         switch (scan_mask) {
 474         case BIT(0) | BIT(1) | BIT(2):
 475                 ret = regmap_bulk_read(regmap, RM3100_REG_MX2, data->buffer, 9);
 476                 mutex_unlock(&data->lock);
 477                 if (ret < 0)
 478                         goto done;
 479                 /* Convert XXXYYYZZZxxx to XXXxYYYxZZZx. x for paddings. */
 480                 for (i = 2; i > 0; i--)
 481                         memmove(data->buffer + i * 4, data->buffer + i * 3, 3);
 482                 break;
 483         case BIT(0) | BIT(1):
 484                 ret = regmap_bulk_read(regmap, RM3100_REG_MX2, data->buffer, 6);
 485                 mutex_unlock(&data->lock);
 486                 if (ret < 0)
 487                         goto done;
 488                 memmove(data->buffer + 4, data->buffer + 3, 3);
 489                 break;
 490         case BIT(1) | BIT(2):
 491                 ret = regmap_bulk_read(regmap, RM3100_REG_MY2, data->buffer, 6);
 492                 mutex_unlock(&data->lock);
 493                 if (ret < 0)
 494                         goto done;
 495                 memmove(data->buffer + 4, data->buffer + 3, 3);
 496                 break;
 497         case BIT(0) | BIT(2):
 498                 ret = regmap_bulk_read(regmap, RM3100_REG_MX2, data->buffer, 9);
 499                 mutex_unlock(&data->lock);
 500                 if (ret < 0)
 501                         goto done;
 502                 memmove(data->buffer + 4, data->buffer + 6, 3);
 503                 break;
 504         default:
 505                 for_each_set_bit(bit, &scan_mask, mask_len) {
 506                         ret = regmap_bulk_read(regmap, RM3100_REG_MX2 + 3 * bit,
 507                                                data->buffer, 3);
 508                         if (ret < 0) {
 509                                 mutex_unlock(&data->lock);
 510                                 goto done;
 511                         }
 512                 }
 513                 mutex_unlock(&data->lock);
 514         }
 515         /*
 516          * Always using the same buffer so that we wouldn't need to set the
 517          * paddings to 0 in case of leaking any data.
 518          */
 519         iio_push_to_buffers_with_timestamp(indio_dev, data->buffer,
 520                                            pf->timestamp);
 521 done:
 522         iio_trigger_notify_done(indio_dev->trig);
 523
 524         return IRQ_HANDLED;
 525 }
 526
 527 int rm3100_common_probe(struct device *dev, struct regmap *regmap, int irq)
 528 {
 529         struct iio_dev *indio_dev;
 530         struct rm3100_data *data;
 531         unsigned int tmp;
 532         int ret;
 533         int samp_rate_index;
 534
 535         indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
 536         if (!indio_dev)
 537                 return -ENOMEM;
 538
 539         data = iio_priv(indio_dev);
 540         data->regmap = regmap;
 541
 542         mutex_init(&data->lock);
 543
 544         indio_dev->name = "rm3100";
 545         indio_dev->info = &rm3100_info;
 546         indio_dev->channels = rm3100_channels;
 547         indio_dev->num_channels = ARRAY_SIZE(rm3100_channels);
 548         indio_dev->modes = INDIO_DIRECT_MODE;
 549
 550         if (!irq)
 551                 data->use_interrupt = false;
 552         else {
 553                 data->use_interrupt = true;
 554
 555                 init_completion(&data->measuring_done);
 556                 ret = devm_request_threaded_irq(dev,
 557                                                 irq,
 558                                                 rm3100_irq_handler,
 559                                                 rm3100_thread_fn,
 560                                                 IRQF_TRIGGER_HIGH |
 561                                                 IRQF_ONESHOT,
 562                                                 indio_dev->name,
 563                                                 indio_dev);
 564                 if (ret < 0) {
 565                         dev_err(dev, "request irq line failed.\n");
 566                         return ret;
 567                 }
 568
 569                 data->drdy_trig = devm_iio_trigger_alloc(dev, "%s-drdy%d",
 570                                                          indio_dev->name,
 571                                                          iio_device_id(indio_dev));
 572                 if (!data->drdy_trig)
 573                         return -ENOMEM;
 574
 575                 ret = devm_iio_trigger_register(dev, data->drdy_trig);
 576                 if (ret < 0)
 577                         return ret;
 578         }
 579
 580         ret = devm_iio_triggered_buffer_setup(dev, indio_dev,
 581                                               &iio_pollfunc_store_time,
 582                                               rm3100_trigger_handler,
 583                                               &rm3100_buffer_ops);
 584         if (ret < 0)
 585                 return ret;
 586
 587         ret = regmap_read(regmap, RM3100_REG_TMRC, &tmp);
 588         if (ret < 0)
 589                 return ret;
 590
 591         samp_rate_index = tmp - RM3100_TMRC_OFFSET;
 592         if (samp_rate_index < 0 || samp_rate_index >=  RM3100_SAMP_NUM) {
 593                 dev_err(dev, "The value read from RM3100_REG_TMRC is invalid!\n");
 594                 return -EINVAL;
 595         }
 596         /* Initializing max wait time, which is double conversion time. */
 597         data->conversion_time = rm3100_samp_rates[samp_rate_index][2] * 2;
 598
 599         /* Cycle count values may not be what we want. */
 600         if ((tmp - RM3100_TMRC_OFFSET) == 0)
 601                 rm3100_set_cycle_count(data, 100);
 602         else
 603                 rm3100_set_cycle_count(data, 200);
 604
 605         return devm_iio_device_register(dev, indio_dev);
 606 }
 607 EXPORT_SYMBOL_NS_GPL(rm3100_common_probe, "IIO_RM3100");
 608
 609 MODULE_AUTHOR("Song Qiang <[email protected]>");
 610 MODULE_DESCRIPTION("PNI RM3100 3-axis magnetometer i2c driver");
 611 MODULE_LICENSE("GPL v2");