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 "rm3100.h"
  26
  27 /* Cycle Count Registers. */
  28 #define RM3100_REG_CC_X                 0x05
  29 #define RM3100_REG_CC_Y                 0x07
  30 #define RM3100_REG_CC_Z                 0x09
  31
  32 /* Poll Measurement Mode register. */
  33 #define RM3100_REG_POLL                 0x00
  34 #define         RM3100_POLL_X           BIT(4)
  35 #define         RM3100_POLL_Y           BIT(5)
  36 #define         RM3100_POLL_Z           BIT(6)
  37
  38 /* Continuous Measurement Mode register. */
  39 #define RM3100_REG_CMM                  0x01
  40 #define         RM3100_CMM_START        BIT(0)
  41 #define         RM3100_CMM_X            BIT(4)
  42 #define         RM3100_CMM_Y            BIT(5)
  43 #define         RM3100_CMM_Z            BIT(6)
  44
  45 /* TiMe Rate Configuration register. */
  46 #define RM3100_REG_TMRC                 0x0B
  47 #define RM3100_TMRC_OFFSET              0x92
  48
  49 /* Result Status register. */
  50 #define RM3100_REG_STATUS               0x34
  51 #define         RM3100_STATUS_DRDY      BIT(7)
  52
  53 /* Measurement result registers. */
  54 #define RM3100_REG_MX2                  0x24
  55 #define RM3100_REG_MY2                  0x27
  56 #define RM3100_REG_MZ2                  0x2a
  57
  58 #define RM3100_W_REG_START              RM3100_REG_POLL
  59 #define RM3100_W_REG_END                RM3100_REG_TMRC
  60 #define RM3100_R_REG_START              RM3100_REG_POLL
  61 #define RM3100_R_REG_END                RM3100_REG_STATUS
  62 #define RM3100_V_REG_START              RM3100_REG_POLL
  63 #define RM3100_V_REG_END                RM3100_REG_STATUS
  64
  65 /*
  66  * This is computed by hand, is the sum of channel storage bits and padding
  67  * bits, which is 4+4+4+12=24 in here.
  68  */
  69 #define RM3100_SCAN_BYTES               24
  70
  71 #define RM3100_CMM_AXIS_SHIFT           4
  72
  73 struct rm3100_data {
  74         struct regmap *regmap;
  75         struct completion measuring_done;
  76         bool use_interrupt;
  77         int conversion_time;
  78         int scale;
  79         u8 buffer[RM3100_SCAN_BYTES];
  80         struct iio_trigger *drdy_trig;
  81
  82         /*
  83          * This lock is for protecting the consistency of series of i2c
  84          * operations, that is, to make sure a measurement process will
  85          * not be interrupted by a set frequency operation, which should
  86          * be taken where a series of i2c operation starts, released where
  87          * the operation ends.
  88          */
  89         struct mutex lock;
  90 };
  91
  92 static const struct regmap_range rm3100_readable_ranges[] = {
  93         regmap_reg_range(RM3100_R_REG_START, RM3100_R_REG_END),
  94 };
  95
  96 const struct regmap_access_table rm3100_readable_table = {
  97         .yes_ranges = rm3100_readable_ranges,
  98         .n_yes_ranges = ARRAY_SIZE(rm3100_readable_ranges),
  99 };
 100 EXPORT_SYMBOL_GPL(rm3100_readable_table);
 101
 102 static const struct regmap_range rm3100_writable_ranges[] = {
 103         regmap_reg_range(RM3100_W_REG_START, RM3100_W_REG_END),
 104 };
 105
 106 const struct regmap_access_table rm3100_writable_table = {
 107         .yes_ranges = rm3100_writable_ranges,
 108         .n_yes_ranges = ARRAY_SIZE(rm3100_writable_ranges),
 109 };
 110 EXPORT_SYMBOL_GPL(rm3100_writable_table);
 111
 112 static const struct regmap_range rm3100_volatile_ranges[] = {
 113         regmap_reg_range(RM3100_V_REG_START, RM3100_V_REG_END),
 114 };
 115
 116 const struct regmap_access_table rm3100_volatile_table = {
 117         .yes_ranges = rm3100_volatile_ranges,
 118         .n_yes_ranges = ARRAY_SIZE(rm3100_volatile_ranges),
 119 };
 120 EXPORT_SYMBOL_GPL(rm3100_volatile_table);
 121
 122 static irqreturn_t rm3100_thread_fn(int irq, void *d)
 123 {
 124         struct iio_dev *indio_dev = d;
 125         struct rm3100_data *data = iio_priv(indio_dev);
 126
 127         /*
 128          * Write operation to any register or read operation
 129          * to first byte of results will clear the interrupt.
 130          */
 131         regmap_write(data->regmap, RM3100_REG_POLL, 0);
 132
 133         return IRQ_HANDLED;
 134 }
 135
 136 static irqreturn_t rm3100_irq_handler(int irq, void *d)
 137 {
 138         struct iio_dev *indio_dev = d;
 139         struct rm3100_data *data = iio_priv(indio_dev);
 140
 141         switch (indio_dev->currentmode) {
 142         case INDIO_DIRECT_MODE:
 143                 complete(&data->measuring_done);
 144                 break;
 145         case INDIO_BUFFER_TRIGGERED:
 146                 iio_trigger_poll(data->drdy_trig);
 147                 break;
 148         default:
 149                 dev_err(indio_dev->dev.parent,
 150                         "device mode out of control, current mode: %d",
 151                         indio_dev->currentmode);
 152         }
 153
 154         return IRQ_WAKE_THREAD;
 155 }
 156
 157 static int rm3100_wait_measurement(struct rm3100_data *data)
 158 {
 159         struct regmap *regmap = data->regmap;
 160         unsigned int val;
 161         int tries = 20;
 162         int ret;
 163
 164         /*
 165          * A read cycle of 400kbits i2c bus is about 20us, plus the time
 166          * used for scheduling, a read cycle of fast mode of this device
 167          * can reach 1.7ms, it may be possible for data to arrive just
 168          * after we check the RM3100_REG_STATUS. In this case, irq_handler is
 169          * called before measuring_done is reinitialized, it will wait
 170          * forever for data that has already been ready.
 171          * Reinitialize measuring_done before looking up makes sure we
 172          * will always capture interrupt no matter when it happens.
 173          */
 174         if (data->use_interrupt)
 175                 reinit_completion(&data->measuring_done);
 176
 177         ret = regmap_read(regmap, RM3100_REG_STATUS, &val);
 178         if (ret < 0)
 179                 return ret;
 180
 181         if ((val & RM3100_STATUS_DRDY) != RM3100_STATUS_DRDY) {
 182                 if (data->use_interrupt) {
 183                         ret = wait_for_completion_timeout(&data->measuring_done,
 184                                 msecs_to_jiffies(data->conversion_time));
 185                         if (!ret)
 186                                 return -ETIMEDOUT;
 187                 } else {
 188                         do {
 189                                 usleep_range(1000, 5000);
 190
 191                                 ret = regmap_read(regmap, RM3100_REG_STATUS,
 192                                                   &val);
 193                                 if (ret < 0)
 194                                         return ret;
 195
 196                                 if (val & RM3100_STATUS_DRDY)
 197                                         break;
 198                         } while (--tries);
 199                         if (!tries)
 200                                 return -ETIMEDOUT;
 201                 }
 202         }
 203         return 0;
 204 }
 205
 206 static int rm3100_read_mag(struct rm3100_data *data, int idx, int *val)
 207 {
 208         struct regmap *regmap = data->regmap;
 209         u8 buffer[3];
 210         int ret;
 211
 212         mutex_lock(&data->lock);
 213         ret = regmap_write(regmap, RM3100_REG_POLL, BIT(4 + idx));
 214         if (ret < 0)
 215                 goto unlock_return;
 216
 217         ret = rm3100_wait_measurement(data);
 218         if (ret < 0)
 219                 goto unlock_return;
 220
 221         ret = regmap_bulk_read(regmap, RM3100_REG_MX2 + 3 * idx, buffer, 3);
 222         if (ret < 0)
 223                 goto unlock_return;
 224         mutex_unlock(&data->lock);
 225
 226         *val = sign_extend32((buffer[0] << 16) | (buffer[1] << 8) | buffer[2],
 227                              23);
 228
 229         return IIO_VAL_INT;
 230
 231 unlock_return:
 232         mutex_unlock(&data->lock);
 233         return ret;
 234 }
 235
 236 #define RM3100_CHANNEL(axis, idx)                                       \
 237         {                                                               \
 238                 .type = IIO_MAGN,                                       \
 239                 .modified = 1,                                          \
 240                 .channel2 = IIO_MOD_##axis,                             \
 241                 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),           \
 242                 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) |  \
 243                         BIT(IIO_CHAN_INFO_SAMP_FREQ),                   \
 244                 .scan_index = idx,                                      \
 245                 .scan_type = {                                          \
 246                         .sign = 's',                                    \
 247                         .realbits = 24,                                 \
 248                         .storagebits = 32,                              \
 249                         .shift = 8,                                     \
 250                         .endianness = IIO_BE,                           \
 251                 },                                                      \
 252         }
 253
 254 static const struct iio_chan_spec rm3100_channels[] = {
 255         RM3100_CHANNEL(X, 0),
 256         RM3100_CHANNEL(Y, 1),
 257         RM3100_CHANNEL(Z, 2),
 258         IIO_CHAN_SOFT_TIMESTAMP(3),
 259 };
 260
 261 static IIO_CONST_ATTR_SAMP_FREQ_AVAIL(
 262         "600 300 150 75 37 18 9 4.5 2.3 1.2 0.6 0.3 0.015 0.075"
 263 );
 264
 265 static struct attribute *rm3100_attributes[] = {
 266         &iio_const_attr_sampling_frequency_available.dev_attr.attr,
 267         NULL,
 268 };
 269
 270 static const struct attribute_group rm3100_attribute_group = {
 271         .attrs = rm3100_attributes,
 272 };
 273
 274 #define RM3100_SAMP_NUM                 14
 275
 276 /*
 277  * Frequency : rm3100_samp_rates[][0].rm3100_samp_rates[][1]Hz.
 278  * Time between reading: rm3100_sam_rates[][2]ms.
 279  * The first one is actually 1.7ms.
 280  */
 281 static const int rm3100_samp_rates[RM3100_SAMP_NUM][3] = {
 282         {600, 0, 2}, {300, 0, 3}, {150, 0, 7}, {75, 0, 13}, {37, 0, 27},
 283         {18, 0, 55}, {9, 0, 110}, {4, 500000, 220}, {2, 300000, 440},
 284         {1, 200000, 800}, {0, 600000, 1600}, {0, 300000, 3300},
 285         {0, 15000, 6700},  {0, 75000, 13000}
 286 };
 287
 288 static int rm3100_get_samp_freq(struct rm3100_data *data, int *val, int *val2)
 289 {
 290         unsigned int tmp;
 291         int ret;
 292
 293         mutex_lock(&data->lock);
 294         ret = regmap_read(data->regmap, RM3100_REG_TMRC, &tmp);
 295         mutex_unlock(&data->lock);
 296         if (ret < 0)
 297                 return ret;
 298         *val = rm3100_samp_rates[tmp - RM3100_TMRC_OFFSET][0];
 299         *val2 = rm3100_samp_rates[tmp - RM3100_TMRC_OFFSET][1];
 300
 301         return IIO_VAL_INT_PLUS_MICRO;
 302 }
 303
 304 static int rm3100_set_cycle_count(struct rm3100_data *data, int val)
 305 {
 306         int ret;
 307         u8 i;
 308
 309         for (i = 0; i < 3; i++) {
 310                 ret = regmap_write(data->regmap, RM3100_REG_CC_X + 2 * i, val);
 311                 if (ret < 0)
 312                         return ret;
 313         }
 314
 315         /*
 316          * The scale of this sensor depends on the cycle count value, these
 317          * three values are corresponding to the cycle count value 50, 100,
 318          * 200. scale = output / gain * 10^4.
 319          */
 320         switch (val) {
 321         case 50:
 322                 data->scale = 500;
 323                 break;
 324         case 100:
 325                 data->scale = 263;
 326                 break;
 327         /*
 328          * case 200:
 329          * This function will never be called by users' code, so here we
 330          * assume that it will never get a wrong parameter.
 331          */
 332         default:
 333                 data->scale = 133;
 334         }
 335
 336         return 0;
 337 }
 338
 339 static int rm3100_set_samp_freq(struct iio_dev *indio_dev, int val, int val2)
 340 {
 341         struct rm3100_data *data = iio_priv(indio_dev);
 342         struct regmap *regmap = data->regmap;
 343         unsigned int cycle_count;
 344         int ret;
 345         int i;
 346
 347         mutex_lock(&data->lock);
 348         /* All cycle count registers use the same value. */
 349         ret = regmap_read(regmap, RM3100_REG_CC_X, &cycle_count);
 350         if (ret < 0)
 351                 goto unlock_return;
 352
 353         for (i = 0; i < RM3100_SAMP_NUM; i++) {
 354                 if (val == rm3100_samp_rates[i][0] &&
 355                     val2 == rm3100_samp_rates[i][1])
 356                         break;
 357         }
 358         if (i == RM3100_SAMP_NUM) {
 359                 ret = -EINVAL;
 360                 goto unlock_return;
 361         }
 362
 363         ret = regmap_write(regmap, RM3100_REG_TMRC, i + RM3100_TMRC_OFFSET);
 364         if (ret < 0)
 365                 goto unlock_return;
 366
 367         /* Checking if cycle count registers need changing. */
 368         if (val == 600 && cycle_count == 200) {
 369                 ret = rm3100_set_cycle_count(data, 100);
 370                 if (ret < 0)
 371                         goto unlock_return;
 372         } else if (val != 600 && cycle_count == 100) {
 373                 ret = rm3100_set_cycle_count(data, 200);
 374                 if (ret < 0)
 375                         goto unlock_return;
 376         }
 377
 378         if (indio_dev->currentmode == INDIO_BUFFER_TRIGGERED) {
 379                 /* Writing TMRC registers requires CMM reset. */
 380                 ret = regmap_write(regmap, RM3100_REG_CMM, 0);
 381                 if (ret < 0)
 382                         goto unlock_return;
 383                 ret = regmap_write(data->regmap, RM3100_REG_CMM,
 384                         (*indio_dev->active_scan_mask & 0x7) <<
 385                         RM3100_CMM_AXIS_SHIFT | RM3100_CMM_START);
 386                 if (ret < 0)
 387                         goto unlock_return;
 388         }
 389         mutex_unlock(&data->lock);
 390
 391         data->conversion_time = rm3100_samp_rates[i][2] * 2;
 392         return 0;
 393
 394 unlock_return:
 395         mutex_unlock(&data->lock);
 396         return ret;
 397 }
 398
 399 static int rm3100_read_raw(struct iio_dev *indio_dev,
 400                            const struct iio_chan_spec *chan,
 401                            int *val, int *val2, long mask)
 402 {
 403         struct rm3100_data *data = iio_priv(indio_dev);
 404         int ret;
 405
 406         switch (mask) {
 407         case IIO_CHAN_INFO_RAW:
 408                 ret = iio_device_claim_direct_mode(indio_dev);
 409                 if (ret < 0)
 410                         return ret;
 411
 412                 ret = rm3100_read_mag(data, chan->scan_index, val);
 413                 iio_device_release_direct_mode(indio_dev);
 414
 415                 return ret;
 416         case IIO_CHAN_INFO_SCALE:
 417                 *val = 0;
 418                 *val2 = data->scale;
 419
 420                 return IIO_VAL_INT_PLUS_MICRO;
 421         case IIO_CHAN_INFO_SAMP_FREQ:
 422                 return rm3100_get_samp_freq(data, val, val2);
 423         default:
 424                 return -EINVAL;
 425         }
 426 }
 427
 428 static int rm3100_write_raw(struct iio_dev *indio_dev,
 429                             struct iio_chan_spec const *chan,
 430                             int val, int val2, long mask)
 431 {
 432         switch (mask) {
 433         case IIO_CHAN_INFO_SAMP_FREQ:
 434                 return rm3100_set_samp_freq(indio_dev, val, val2);
 435         default:
 436                 return -EINVAL;
 437         }
 438 }
 439
 440 static const struct iio_info rm3100_info = {
 441         .attrs = &rm3100_attribute_group,
 442         .read_raw = rm3100_read_raw,
 443         .write_raw = rm3100_write_raw,
 444 };
 445
 446 static int rm3100_buffer_preenable(struct iio_dev *indio_dev)
 447 {
 448         struct rm3100_data *data = iio_priv(indio_dev);
 449
 450         /* Starting channels enabled. */
 451         return regmap_write(data->regmap, RM3100_REG_CMM,
 452                 (*indio_dev->active_scan_mask & 0x7) << RM3100_CMM_AXIS_SHIFT |
 453                 RM3100_CMM_START);
 454 }
 455
 456 static int rm3100_buffer_postdisable(struct iio_dev *indio_dev)
 457 {
 458         struct rm3100_data *data = iio_priv(indio_dev);
 459
 460         return regmap_write(data->regmap, RM3100_REG_CMM, 0);
 461 }
 462
 463 static const struct iio_buffer_setup_ops rm3100_buffer_ops = {
 464         .preenable = rm3100_buffer_preenable,
 465         .postenable = iio_triggered_buffer_postenable,
 466         .predisable = iio_triggered_buffer_predisable,
 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->dev.parent = dev;
 552         indio_dev->name = "rm3100";
 553         indio_dev->info = &rm3100_info;
 554         indio_dev->channels = rm3100_channels;
 555         indio_dev->num_channels = ARRAY_SIZE(rm3100_channels);
 556         indio_dev->modes = INDIO_DIRECT_MODE | INDIO_BUFFER_TRIGGERED;
 557         indio_dev->currentmode = INDIO_DIRECT_MODE;
 558
 559         if (!irq)
 560                 data->use_interrupt = false;
 561         else {
 562                 data->use_interrupt = true;
 563
 564                 init_completion(&data->measuring_done);
 565                 ret = devm_request_threaded_irq(dev,
 566                                                 irq,
 567                                                 rm3100_irq_handler,
 568                                                 rm3100_thread_fn,
 569                                                 IRQF_TRIGGER_HIGH |
 570                                                 IRQF_ONESHOT,
 571                                                 indio_dev->name,
 572                                                 indio_dev);
 573                 if (ret < 0) {
 574                         dev_err(dev, "request irq line failed.\n");
 575                         return ret;
 576                 }
 577
 578                 data->drdy_trig = devm_iio_trigger_alloc(dev, "%s-drdy%d",
 579                                                          indio_dev->name,
 580                                                          indio_dev->id);
 581                 if (!data->drdy_trig)
 582                         return -ENOMEM;
 583
 584                 data->drdy_trig->dev.parent = dev;
 585                 ret = devm_iio_trigger_register(dev, data->drdy_trig);
 586                 if (ret < 0)
 587                         return ret;
 588         }
 589
 590         ret = devm_iio_triggered_buffer_setup(dev, indio_dev,
 591                                               &iio_pollfunc_store_time,
 592                                               rm3100_trigger_handler,
 593                                               &rm3100_buffer_ops);
 594         if (ret < 0)
 595                 return ret;
 596
 597         ret = regmap_read(regmap, RM3100_REG_TMRC, &tmp);
 598         if (ret < 0)
 599                 return ret;
 600         /* Initializing max wait time, which is double conversion time. */
 601         data->conversion_time = rm3100_samp_rates[tmp - RM3100_TMRC_OFFSET][2]
 602                                 * 2;
 603
 604         /* Cycle count values may not be what we want. */
 605         if ((tmp - RM3100_TMRC_OFFSET) == 0)
 606                 rm3100_set_cycle_count(data, 100);
 607         else
 608                 rm3100_set_cycle_count(data, 200);
 609
 610         return devm_iio_device_register(dev, indio_dev);
 611 }
 612 EXPORT_SYMBOL_GPL(rm3100_common_probe);
 613
 614 MODULE_AUTHOR("Song Qiang <songqiang1304521@gmail.com>");
 615 MODULE_DESCRIPTION("PNI RM3100 3-axis magnetometer i2c driver");
 616 MODULE_LICENSE("GPL v2");