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 <songqiang1304521@gmail.com>
   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 <asm/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_GPL(rm3100_readable_table);
 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_GPL(rm3100_writable_table);
 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_GPL(rm3100_volatile_table);
 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         switch (indio_dev->currentmode) {
 145         case INDIO_DIRECT_MODE:
 146                 complete(&data->measuring_done);
 147                 break;
 148         case INDIO_BUFFER_TRIGGERED:
 149                 iio_trigger_poll(data->drdy_trig);
 150                 break;
 151         default:
 152                 dev_err(indio_dev->dev.parent,
 153                         "device mode out of control, current mode: %d",
 154                         indio_dev->currentmode);
 155         }
 156
 157         return IRQ_WAKE_THREAD;
 158 }
 159
 160 static int rm3100_wait_measurement(struct rm3100_data *data)
 161 {
 162         struct regmap *regmap = data->regmap;
 163         unsigned int val;
 164         int tries = 20;
 165         int ret;
 166
 167         /*
 168          * A read cycle of 400kbits i2c bus is about 20us, plus the time
 169          * used for scheduling, a read cycle of fast mode of this device
 170          * can reach 1.7ms, it may be possible for data to arrive just
 171          * after we check the RM3100_REG_STATUS. In this case, irq_handler is
 172          * called before measuring_done is reinitialized, it will wait
 173          * forever for data that has already been ready.
 174          * Reinitialize measuring_done before looking up makes sure we
 175          * will always capture interrupt no matter when it happens.
 176          */
 177         if (data->use_interrupt)
 178                 reinit_completion(&data->measuring_done);
 179
 180         ret = regmap_read(regmap, RM3100_REG_STATUS, &val);
 181         if (ret < 0)
 182                 return ret;
 183
 184         if ((val & RM3100_STATUS_DRDY) != RM3100_STATUS_DRDY) {
 185                 if (data->use_interrupt) {
 186                         ret = wait_for_completion_timeout(&data->measuring_done,
 187                                 msecs_to_jiffies(data->conversion_time));
 188                         if (!ret)
 189                                 return -ETIMEDOUT;
 190                 } else {
 191                         do {
 192                                 usleep_range(1000, 5000);
 193
 194                                 ret = regmap_read(regmap, RM3100_REG_STATUS,
 195                                                   &val);
 196                                 if (ret < 0)
 197                                         return ret;
 198
 199                                 if (val & RM3100_STATUS_DRDY)
 200                                         break;
 201                         } while (--tries);
 202                         if (!tries)
 203                                 return -ETIMEDOUT;
 204                 }
 205         }
 206         return 0;
 207 }
 208
 209 static int rm3100_read_mag(struct rm3100_data *data, int idx, int *val)
 210 {
 211         struct regmap *regmap = data->regmap;
 212         u8 buffer[3];
 213         int ret;
 214
 215         mutex_lock(&data->lock);
 216         ret = regmap_write(regmap, RM3100_REG_POLL, BIT(4 + idx));
 217         if (ret < 0)
 218                 goto unlock_return;
 219
 220         ret = rm3100_wait_measurement(data);
 221         if (ret < 0)
 222                 goto unlock_return;
 223
 224         ret = regmap_bulk_read(regmap, RM3100_REG_MX2 + 3 * idx, buffer, 3);
 225         if (ret < 0)
 226                 goto unlock_return;
 227         mutex_unlock(&data->lock);
 228
 229         *val = sign_extend32(get_unaligned_be24(&buffer[0]), 23);
 230
 231         return IIO_VAL_INT;
 232
 233 unlock_return:
 234         mutex_unlock(&data->lock);
 235         return ret;
 236 }
 237
 238 #define RM3100_CHANNEL(axis, idx)                                       \
 239         {                                                               \
 240                 .type = IIO_MAGN,                                       \
 241                 .modified = 1,                                          \
 242                 .channel2 = IIO_MOD_##axis,                             \
 243                 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),           \
 244                 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) |  \
 245                         BIT(IIO_CHAN_INFO_SAMP_FREQ),                   \
 246                 .scan_index = idx,                                      \
 247                 .scan_type = {                                          \
 248                         .sign = 's',                                    \
 249                         .realbits = 24,                                 \
 250                         .storagebits = 32,                              \
 251                         .shift = 8,                                     \
 252                         .endianness = IIO_BE,                           \
 253                 },                                                      \
 254         }
 255
 256 static const struct iio_chan_spec rm3100_channels[] = {
 257         RM3100_CHANNEL(X, 0),
 258         RM3100_CHANNEL(Y, 1),
 259         RM3100_CHANNEL(Z, 2),
 260         IIO_CHAN_SOFT_TIMESTAMP(3),
 261 };
 262
 263 static IIO_CONST_ATTR_SAMP_FREQ_AVAIL(
 264         "600 300 150 75 37 18 9 4.5 2.3 1.2 0.6 0.3 0.015 0.075"
 265 );
 266
 267 static struct attribute *rm3100_attributes[] = {
 268         &iio_const_attr_sampling_frequency_available.dev_attr.attr,
 269         NULL,
 270 };
 271
 272 static const struct attribute_group rm3100_attribute_group = {
 273         .attrs = rm3100_attributes,
 274 };
 275
 276 #define RM3100_SAMP_NUM                 14
 277
 278 /*
 279  * Frequency : rm3100_samp_rates[][0].rm3100_samp_rates[][1]Hz.
 280  * Time between reading: rm3100_sam_rates[][2]ms.
 281  * The first one is actually 1.7ms.
 282  */
 283 static const int rm3100_samp_rates[RM3100_SAMP_NUM][3] = {
 284         {600, 0, 2}, {300, 0, 3}, {150, 0, 7}, {75, 0, 13}, {37, 0, 27},
 285         {18, 0, 55}, {9, 0, 110}, {4, 500000, 220}, {2, 300000, 440},
 286         {1, 200000, 800}, {0, 600000, 1600}, {0, 300000, 3300},
 287         {0, 15000, 6700},  {0, 75000, 13000}
 288 };
 289
 290 static int rm3100_get_samp_freq(struct rm3100_data *data, int *val, int *val2)
 291 {
 292         unsigned int tmp;
 293         int ret;
 294
 295         mutex_lock(&data->lock);
 296         ret = regmap_read(data->regmap, RM3100_REG_TMRC, &tmp);
 297         mutex_unlock(&data->lock);
 298         if (ret < 0)
 299                 return ret;
 300         *val = rm3100_samp_rates[tmp - RM3100_TMRC_OFFSET][0];
 301         *val2 = rm3100_samp_rates[tmp - RM3100_TMRC_OFFSET][1];
 302
 303         return IIO_VAL_INT_PLUS_MICRO;
 304 }
 305
 306 static int rm3100_set_cycle_count(struct rm3100_data *data, int val)
 307 {
 308         int ret;
 309         u8 i;
 310
 311         for (i = 0; i < 3; i++) {
 312                 ret = regmap_write(data->regmap, RM3100_REG_CC_X + 2 * i, val);
 313                 if (ret < 0)
 314                         return ret;
 315         }
 316
 317         /*
 318          * The scale of this sensor depends on the cycle count value, these
 319          * three values are corresponding to the cycle count value 50, 100,
 320          * 200. scale = output / gain * 10^4.
 321          */
 322         switch (val) {
 323         case 50:
 324                 data->scale = 500;
 325                 break;
 326         case 100:
 327                 data->scale = 263;
 328                 break;
 329         /*
 330          * case 200:
 331          * This function will never be called by users' code, so here we
 332          * assume that it will never get a wrong parameter.
 333          */
 334         default:
 335                 data->scale = 133;
 336         }
 337
 338         return 0;
 339 }
 340
 341 static int rm3100_set_samp_freq(struct iio_dev *indio_dev, int val, int val2)
 342 {
 343         struct rm3100_data *data = iio_priv(indio_dev);
 344         struct regmap *regmap = data->regmap;
 345         unsigned int cycle_count;
 346         int ret;
 347         int i;
 348
 349         mutex_lock(&data->lock);
 350         /* All cycle count registers use the same value. */
 351         ret = regmap_read(regmap, RM3100_REG_CC_X, &cycle_count);
 352         if (ret < 0)
 353                 goto unlock_return;
 354
 355         for (i = 0; i < RM3100_SAMP_NUM; i++) {
 356                 if (val == rm3100_samp_rates[i][0] &&
 357                     val2 == rm3100_samp_rates[i][1])
 358                         break;
 359         }
 360         if (i == RM3100_SAMP_NUM) {
 361                 ret = -EINVAL;
 362                 goto unlock_return;
 363         }
 364
 365         ret = regmap_write(regmap, RM3100_REG_TMRC, i + RM3100_TMRC_OFFSET);
 366         if (ret < 0)
 367                 goto unlock_return;
 368
 369         /* Checking if cycle count registers need changing. */
 370         if (val == 600 && cycle_count == 200) {
 371                 ret = rm3100_set_cycle_count(data, 100);
 372                 if (ret < 0)
 373                         goto unlock_return;
 374         } else if (val != 600 && cycle_count == 100) {
 375                 ret = rm3100_set_cycle_count(data, 200);
 376                 if (ret < 0)
 377                         goto unlock_return;
 378         }
 379
 380         if (indio_dev->currentmode == INDIO_BUFFER_TRIGGERED) {
 381                 /* Writing TMRC registers requires CMM reset. */
 382                 ret = regmap_write(regmap, RM3100_REG_CMM, 0);
 383                 if (ret < 0)
 384                         goto unlock_return;
 385                 ret = regmap_write(data->regmap, RM3100_REG_CMM,
 386                         (*indio_dev->active_scan_mask & 0x7) <<
 387                         RM3100_CMM_AXIS_SHIFT | RM3100_CMM_START);
 388                 if (ret < 0)
 389                         goto unlock_return;
 390         }
 391         mutex_unlock(&data->lock);
 392
 393         data->conversion_time = rm3100_samp_rates[i][2] * 2;
 394         return 0;
 395
 396 unlock_return:
 397         mutex_unlock(&data->lock);
 398         return ret;
 399 }
 400
 401 static int rm3100_read_raw(struct iio_dev *indio_dev,
 402                            const struct iio_chan_spec *chan,
 403                            int *val, int *val2, long mask)
 404 {
 405         struct rm3100_data *data = iio_priv(indio_dev);
 406         int ret;
 407
 408         switch (mask) {
 409         case IIO_CHAN_INFO_RAW:
 410                 ret = iio_device_claim_direct_mode(indio_dev);
 411                 if (ret < 0)
 412                         return ret;
 413
 414                 ret = rm3100_read_mag(data, chan->scan_index, val);
 415                 iio_device_release_direct_mode(indio_dev);
 416
 417                 return ret;
 418         case IIO_CHAN_INFO_SCALE:
 419                 *val = 0;
 420                 *val2 = data->scale;
 421
 422                 return IIO_VAL_INT_PLUS_MICRO;
 423         case IIO_CHAN_INFO_SAMP_FREQ:
 424                 return rm3100_get_samp_freq(data, val, val2);
 425         default:
 426                 return -EINVAL;
 427         }
 428 }
 429
 430 static int rm3100_write_raw(struct iio_dev *indio_dev,
 431                             struct iio_chan_spec const *chan,
 432                             int val, int val2, long mask)
 433 {
 434         switch (mask) {
 435         case IIO_CHAN_INFO_SAMP_FREQ:
 436                 return rm3100_set_samp_freq(indio_dev, val, val2);
 437         default:
 438                 return -EINVAL;
 439         }
 440 }
 441
 442 static const struct iio_info rm3100_info = {
 443         .attrs = &rm3100_attribute_group,
 444         .read_raw = rm3100_read_raw,
 445         .write_raw = rm3100_write_raw,
 446 };
 447
 448 static int rm3100_buffer_preenable(struct iio_dev *indio_dev)
 449 {
 450         struct rm3100_data *data = iio_priv(indio_dev);
 451
 452         /* Starting channels enabled. */
 453         return regmap_write(data->regmap, RM3100_REG_CMM,
 454                 (*indio_dev->active_scan_mask & 0x7) << RM3100_CMM_AXIS_SHIFT |
 455                 RM3100_CMM_START);
 456 }
 457
 458 static int rm3100_buffer_postdisable(struct iio_dev *indio_dev)
 459 {
 460         struct rm3100_data *data = iio_priv(indio_dev);
 461
 462         return regmap_write(data->regmap, RM3100_REG_CMM, 0);
 463 }
 464
 465 static const struct iio_buffer_setup_ops rm3100_buffer_ops = {
 466         .preenable = rm3100_buffer_preenable,
 467         .postdisable = rm3100_buffer_postdisable,
 468 };
 469
 470 static irqreturn_t rm3100_trigger_handler(int irq, void *p)
 471 {
 472         struct iio_poll_func *pf = p;
 473         struct iio_dev *indio_dev = pf->indio_dev;
 474         unsigned long scan_mask = *indio_dev->active_scan_mask;
 475         unsigned int mask_len = indio_dev->masklength;
 476         struct rm3100_data *data = iio_priv(indio_dev);
 477         struct regmap *regmap = data->regmap;
 478         int ret, i, bit;
 479
 480         mutex_lock(&data->lock);
 481         switch (scan_mask) {
 482         case BIT(0) | BIT(1) | BIT(2):
 483                 ret = regmap_bulk_read(regmap, RM3100_REG_MX2, data->buffer, 9);
 484                 mutex_unlock(&data->lock);
 485                 if (ret < 0)
 486                         goto done;
 487                 /* Convert XXXYYYZZZxxx to XXXxYYYxZZZx. x for paddings. */
 488                 for (i = 2; i > 0; i--)
 489                         memmove(data->buffer + i * 4, data->buffer + i * 3, 3);
 490                 break;
 491         case BIT(0) | BIT(1):
 492                 ret = regmap_bulk_read(regmap, RM3100_REG_MX2, data->buffer, 6);
 493                 mutex_unlock(&data->lock);
 494                 if (ret < 0)
 495                         goto done;
 496                 memmove(data->buffer + 4, data->buffer + 3, 3);
 497                 break;
 498         case BIT(1) | BIT(2):
 499                 ret = regmap_bulk_read(regmap, RM3100_REG_MY2, data->buffer, 6);
 500                 mutex_unlock(&data->lock);
 501                 if (ret < 0)
 502                         goto done;
 503                 memmove(data->buffer + 4, data->buffer + 3, 3);
 504                 break;
 505         case BIT(0) | BIT(2):
 506                 ret = regmap_bulk_read(regmap, RM3100_REG_MX2, data->buffer, 9);
 507                 mutex_unlock(&data->lock);
 508                 if (ret < 0)
 509                         goto done;
 510                 memmove(data->buffer + 4, data->buffer + 6, 3);
 511                 break;
 512         default:
 513                 for_each_set_bit(bit, &scan_mask, mask_len) {
 514                         ret = regmap_bulk_read(regmap, RM3100_REG_MX2 + 3 * bit,
 515                                                data->buffer, 3);
 516                         if (ret < 0) {
 517                                 mutex_unlock(&data->lock);
 518                                 goto done;
 519                         }
 520                 }
 521                 mutex_unlock(&data->lock);
 522         }
 523         /*
 524          * Always using the same buffer so that we wouldn't need to set the
 525          * paddings to 0 in case of leaking any data.
 526          */
 527         iio_push_to_buffers_with_timestamp(indio_dev, data->buffer,
 528                                            pf->timestamp);
 529 done:
 530         iio_trigger_notify_done(indio_dev->trig);
 531
 532         return IRQ_HANDLED;
 533 }
 534
 535 int rm3100_common_probe(struct device *dev, struct regmap *regmap, int irq)
 536 {
 537         struct iio_dev *indio_dev;
 538         struct rm3100_data *data;
 539         unsigned int tmp;
 540         int ret;
 541
 542         indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
 543         if (!indio_dev)
 544                 return -ENOMEM;
 545
 546         data = iio_priv(indio_dev);
 547         data->regmap = regmap;
 548
 549         mutex_init(&data->lock);
 550
 551         indio_dev->name = "rm3100";
 552         indio_dev->info = &rm3100_info;
 553         indio_dev->channels = rm3100_channels;
 554         indio_dev->num_channels = ARRAY_SIZE(rm3100_channels);
 555         indio_dev->modes = INDIO_DIRECT_MODE | INDIO_BUFFER_TRIGGERED;
 556         indio_dev->currentmode = INDIO_DIRECT_MODE;
 557
 558         if (!irq)
 559                 data->use_interrupt = false;
 560         else {
 561                 data->use_interrupt = true;
 562
 563                 init_completion(&data->measuring_done);
 564                 ret = devm_request_threaded_irq(dev,
 565                                                 irq,
 566                                                 rm3100_irq_handler,
 567                                                 rm3100_thread_fn,
 568                                                 IRQF_TRIGGER_HIGH |
 569                                                 IRQF_ONESHOT,
 570                                                 indio_dev->name,
 571                                                 indio_dev);
 572                 if (ret < 0) {
 573                         dev_err(dev, "request irq line failed.\n");
 574                         return ret;
 575                 }
 576
 577                 data->drdy_trig = devm_iio_trigger_alloc(dev, "%s-drdy%d",
 578                                                          indio_dev->name,
 579                                                          iio_device_id(indio_dev));
 580                 if (!data->drdy_trig)
 581                         return -ENOMEM;
 582
 583                 ret = devm_iio_trigger_register(dev, data->drdy_trig);
 584                 if (ret < 0)
 585                         return ret;
 586         }
 587
 588         ret = devm_iio_triggered_buffer_setup(dev, indio_dev,
 589                                               &iio_pollfunc_store_time,
 590                                               rm3100_trigger_handler,
 591                                               &rm3100_buffer_ops);
 592         if (ret < 0)
 593                 return ret;
 594
 595         ret = regmap_read(regmap, RM3100_REG_TMRC, &tmp);
 596         if (ret < 0)
 597                 return ret;
 598         /* Initializing max wait time, which is double conversion time. */
 599         data->conversion_time = rm3100_samp_rates[tmp - RM3100_TMRC_OFFSET][2]
 600                                 * 2;
 601
 602         /* Cycle count values may not be what we want. */
 603         if ((tmp - RM3100_TMRC_OFFSET) == 0)
 604                 rm3100_set_cycle_count(data, 100);
 605         else
 606                 rm3100_set_cycle_count(data, 200);
 607
 608         return devm_iio_device_register(dev, indio_dev);
 609 }
 610 EXPORT_SYMBOL_GPL(rm3100_common_probe);
 611
 612 MODULE_AUTHOR("Song Qiang <songqiang1304521@gmail.com>");
 613 MODULE_DESCRIPTION("PNI RM3100 3-axis magnetometer i2c driver");
 614 MODULE_LICENSE("GPL v2");