linux/drivers/iio/magnetometer/mmc35240.c
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   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/acpi.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
  83enum 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
  90enum mmc35240_axis {
  91        AXIS_X = 0,
  92        AXIS_Y,
  93        AXIS_Z,
  94};
  95
  96static 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
 122struct 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
 133static const struct {
 134        int val;
 135        int val2;
 136} mmc35240_samp_freq[] = { {1, 500000},
 137                           {13, 0},
 138                           {25, 0},
 139                           {50, 0} };
 140
 141static 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
 153static const struct iio_chan_spec mmc35240_channels[] = {
 154        MMC35240_CHANNEL(X),
 155        MMC35240_CHANNEL(Y),
 156        MMC35240_CHANNEL(Z),
 157};
 158
 159static struct attribute *mmc35240_attributes[] = {
 160        &iio_const_attr_sampling_frequency_available.dev_attr.attr,
 161        NULL
 162};
 163
 164static const struct attribute_group mmc35240_attribute_group = {
 165        .attrs = mmc35240_attributes,
 166};
 167
 168static 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
 180static 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_update_bits(data->regmap, MMC35240_REG_CTRL0,
 190                                 MMC35240_CTRL0_REFILL_BIT,
 191                                 MMC35240_CTRL0_REFILL_BIT);
 192        if (ret < 0)
 193                return ret;
 194        usleep_range(MMC35240_WAIT_CHARGE_PUMP, MMC35240_WAIT_CHARGE_PUMP + 1);
 195
 196        if (set)
 197                coil_bit = MMC35240_CTRL0_SET_BIT;
 198        else
 199                coil_bit = MMC35240_CTRL0_RESET_BIT;
 200
 201        return regmap_update_bits(data->regmap, MMC35240_REG_CTRL0,
 202                                  coil_bit, coil_bit);
 203
 204}
 205
 206static int mmc35240_init(struct mmc35240_data *data)
 207{
 208        int ret, y_convert, z_convert;
 209        unsigned int reg_id;
 210        u8 otp_data[6];
 211
 212        ret = regmap_read(data->regmap, MMC35240_REG_ID, &reg_id);
 213        if (ret < 0) {
 214                dev_err(&data->client->dev, "Error reading product id\n");
 215                return ret;
 216        }
 217
 218        dev_dbg(&data->client->dev, "MMC35240 chip id %x\n", reg_id);
 219
 220        /*
 221         * make sure we restore sensor characteristics, by doing
 222         * a SET/RESET sequence, the axis polarity being naturally
 223         * aligned after RESET
 224         */
 225        ret = mmc35240_hw_set(data, true);
 226        if (ret < 0)
 227                return ret;
 228        usleep_range(MMC35240_WAIT_SET_RESET, MMC35240_WAIT_SET_RESET + 1);
 229
 230        ret = mmc35240_hw_set(data, false);
 231        if (ret < 0)
 232                return ret;
 233
 234        /* set default sampling frequency */
 235        ret = regmap_update_bits(data->regmap, MMC35240_REG_CTRL1,
 236                                 MMC35240_CTRL1_BW_MASK,
 237                                 data->res << MMC35240_CTRL1_BW_SHIFT);
 238        if (ret < 0)
 239                return ret;
 240
 241        ret = regmap_bulk_read(data->regmap, MMC35240_OTP_START_ADDR,
 242                               otp_data, sizeof(otp_data));
 243        if (ret < 0)
 244                return ret;
 245
 246        y_convert = MMC35240_OTP_CONVERT_Y(((otp_data[1] & 0x03) << 4) |
 247                                           (otp_data[2] >> 4));
 248        z_convert = MMC35240_OTP_CONVERT_Z(otp_data[3] & 0x3f);
 249
 250        data->axis_coef[0] = MMC35240_X_COEFF(1);
 251        data->axis_coef[1] = MMC35240_Y_COEFF(y_convert);
 252        data->axis_coef[2] = MMC35240_Z_COEFF(z_convert);
 253
 254        data->axis_scale[0] = 1;
 255        data->axis_scale[1] = 1000;
 256        data->axis_scale[2] = 10000;
 257
 258        return 0;
 259}
 260
 261static int mmc35240_take_measurement(struct mmc35240_data *data)
 262{
 263        int ret, tries = 100;
 264        unsigned int reg_status;
 265
 266        ret = regmap_write(data->regmap, MMC35240_REG_CTRL0,
 267                           MMC35240_CTRL0_TM_BIT);
 268        if (ret < 0)
 269                return ret;
 270
 271        while (tries-- > 0) {
 272                ret = regmap_read(data->regmap, MMC35240_REG_STATUS,
 273                                  &reg_status);
 274                if (ret < 0)
 275                        return ret;
 276                if (reg_status & MMC35240_STATUS_MEAS_DONE_BIT)
 277                        break;
 278                /* minimum wait time to complete measurement is 10 ms */
 279                usleep_range(10000, 11000);
 280        }
 281
 282        if (tries < 0) {
 283                dev_err(&data->client->dev, "data not ready\n");
 284                return -EIO;
 285        }
 286
 287        return 0;
 288}
 289
 290static int mmc35240_read_measurement(struct mmc35240_data *data, __le16 buf[3])
 291{
 292        int ret;
 293
 294        ret = mmc35240_take_measurement(data);
 295        if (ret < 0)
 296                return ret;
 297
 298        return regmap_bulk_read(data->regmap, MMC35240_REG_XOUT_L, buf,
 299                                3 * sizeof(__le16));
 300}
 301
 302/**
 303 * mmc35240_raw_to_mgauss - convert raw readings to milli gauss. Also apply
 304 *                          compensation for output value.
 305 *
 306 * @data: device private data
 307 * @index: axis index for which we want the conversion
 308 * @buf: raw data to be converted, 2 bytes in little endian format
 309 * @val: compensated output reading (unit is milli gauss)
 310 *
 311 * Returns: 0 in case of success, -EINVAL when @index is not valid
 312 */
 313static int mmc35240_raw_to_mgauss(struct mmc35240_data *data, int index,
 314                                  __le16 buf[], int *val)
 315{
 316        int raw[3];
 317        int sens[3];
 318        int nfo;
 319
 320        raw[AXIS_X] = le16_to_cpu(buf[AXIS_X]);
 321        raw[AXIS_Y] = le16_to_cpu(buf[AXIS_Y]);
 322        raw[AXIS_Z] = le16_to_cpu(buf[AXIS_Z]);
 323
 324        sens[AXIS_X] = mmc35240_props_table[data->res].sens[AXIS_X];
 325        sens[AXIS_Y] = mmc35240_props_table[data->res].sens[AXIS_Y];
 326        sens[AXIS_Z] = mmc35240_props_table[data->res].sens[AXIS_Z];
 327
 328        nfo = mmc35240_props_table[data->res].nfo;
 329
 330        switch (index) {
 331        case AXIS_X:
 332                *val = (raw[AXIS_X] - nfo) * 1000 / sens[AXIS_X];
 333                break;
 334        case AXIS_Y:
 335                *val = (raw[AXIS_Y] - nfo) * 1000 / sens[AXIS_Y] -
 336                        (raw[AXIS_Z] - nfo)  * 1000 / sens[AXIS_Z];
 337                break;
 338        case AXIS_Z:
 339                *val = (raw[AXIS_Y] - nfo) * 1000 / sens[AXIS_Y] +
 340                        (raw[AXIS_Z] - nfo) * 1000 / sens[AXIS_Z];
 341                break;
 342        default:
 343                return -EINVAL;
 344        }
 345        /* apply OTP compensation */
 346        *val = (*val) * data->axis_coef[index] / data->axis_scale[index];
 347
 348        return 0;
 349}
 350
 351static int mmc35240_read_raw(struct iio_dev *indio_dev,
 352                             struct iio_chan_spec const *chan, int *val,
 353                             int *val2, long mask)
 354{
 355        struct mmc35240_data *data = iio_priv(indio_dev);
 356        int ret, i;
 357        unsigned int reg;
 358        __le16 buf[3];
 359
 360        switch (mask) {
 361        case IIO_CHAN_INFO_RAW:
 362                mutex_lock(&data->mutex);
 363                ret = mmc35240_read_measurement(data, buf);
 364                mutex_unlock(&data->mutex);
 365                if (ret < 0)
 366                        return ret;
 367                ret = mmc35240_raw_to_mgauss(data, chan->address, buf, val);
 368                if (ret < 0)
 369                        return ret;
 370                return IIO_VAL_INT;
 371        case IIO_CHAN_INFO_SCALE:
 372                *val = 0;
 373                *val2 = 1000;
 374                return IIO_VAL_INT_PLUS_MICRO;
 375        case IIO_CHAN_INFO_SAMP_FREQ:
 376                mutex_lock(&data->mutex);
 377                ret = regmap_read(data->regmap, MMC35240_REG_CTRL1, &reg);
 378                mutex_unlock(&data->mutex);
 379                if (ret < 0)
 380                        return ret;
 381
 382                i = (reg & MMC35240_CTRL1_BW_MASK) >> MMC35240_CTRL1_BW_SHIFT;
 383                if (i < 0 || i >= ARRAY_SIZE(mmc35240_samp_freq))
 384                        return -EINVAL;
 385
 386                *val = mmc35240_samp_freq[i].val;
 387                *val2 = mmc35240_samp_freq[i].val2;
 388                return IIO_VAL_INT_PLUS_MICRO;
 389        default:
 390                return -EINVAL;
 391        }
 392}
 393
 394static int mmc35240_write_raw(struct iio_dev *indio_dev,
 395                              struct iio_chan_spec const *chan, int val,
 396                              int val2, long mask)
 397{
 398        struct mmc35240_data *data = iio_priv(indio_dev);
 399        int i, ret;
 400
 401        switch (mask) {
 402        case IIO_CHAN_INFO_SAMP_FREQ:
 403                i = mmc35240_get_samp_freq_index(data, val, val2);
 404                if (i < 0)
 405                        return -EINVAL;
 406                mutex_lock(&data->mutex);
 407                ret = regmap_update_bits(data->regmap, MMC35240_REG_CTRL1,
 408                                         MMC35240_CTRL1_BW_MASK,
 409                                         i << MMC35240_CTRL1_BW_SHIFT);
 410                mutex_unlock(&data->mutex);
 411                return ret;
 412        default:
 413                return -EINVAL;
 414        }
 415}
 416
 417static const struct iio_info mmc35240_info = {
 418        .read_raw       = mmc35240_read_raw,
 419        .write_raw      = mmc35240_write_raw,
 420        .attrs          = &mmc35240_attribute_group,
 421};
 422
 423static bool mmc35240_is_writeable_reg(struct device *dev, unsigned int reg)
 424{
 425        switch (reg) {
 426        case MMC35240_REG_CTRL0:
 427        case MMC35240_REG_CTRL1:
 428                return true;
 429        default:
 430                return false;
 431        }
 432}
 433
 434static bool mmc35240_is_readable_reg(struct device *dev, unsigned int reg)
 435{
 436        switch (reg) {
 437        case MMC35240_REG_XOUT_L:
 438        case MMC35240_REG_XOUT_H:
 439        case MMC35240_REG_YOUT_L:
 440        case MMC35240_REG_YOUT_H:
 441        case MMC35240_REG_ZOUT_L:
 442        case MMC35240_REG_ZOUT_H:
 443        case MMC35240_REG_STATUS:
 444        case MMC35240_REG_ID:
 445                return true;
 446        default:
 447                return false;
 448        }
 449}
 450
 451static bool mmc35240_is_volatile_reg(struct device *dev, unsigned int reg)
 452{
 453        switch (reg) {
 454        case MMC35240_REG_CTRL0:
 455        case MMC35240_REG_CTRL1:
 456                return false;
 457        default:
 458                return true;
 459        }
 460}
 461
 462static const struct reg_default mmc35240_reg_defaults[] = {
 463        { MMC35240_REG_CTRL0,  0x00 },
 464        { MMC35240_REG_CTRL1,  0x00 },
 465};
 466
 467static const struct regmap_config mmc35240_regmap_config = {
 468        .name = MMC35240_REGMAP_NAME,
 469
 470        .reg_bits = 8,
 471        .val_bits = 8,
 472
 473        .max_register = MMC35240_REG_ID,
 474        .cache_type = REGCACHE_FLAT,
 475
 476        .writeable_reg = mmc35240_is_writeable_reg,
 477        .readable_reg = mmc35240_is_readable_reg,
 478        .volatile_reg = mmc35240_is_volatile_reg,
 479
 480        .reg_defaults = mmc35240_reg_defaults,
 481        .num_reg_defaults = ARRAY_SIZE(mmc35240_reg_defaults),
 482};
 483
 484static int mmc35240_probe(struct i2c_client *client,
 485                          const struct i2c_device_id *id)
 486{
 487        struct mmc35240_data *data;
 488        struct iio_dev *indio_dev;
 489        struct regmap *regmap;
 490        int ret;
 491
 492        indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
 493        if (!indio_dev)
 494                return -ENOMEM;
 495
 496        regmap = devm_regmap_init_i2c(client, &mmc35240_regmap_config);
 497        if (IS_ERR(regmap)) {
 498                dev_err(&client->dev, "regmap initialization failed\n");
 499                return PTR_ERR(regmap);
 500        }
 501
 502        data = iio_priv(indio_dev);
 503        i2c_set_clientdata(client, indio_dev);
 504        data->client = client;
 505        data->regmap = regmap;
 506        data->res = MMC35240_16_BITS_SLOW;
 507
 508        mutex_init(&data->mutex);
 509
 510        indio_dev->info = &mmc35240_info;
 511        indio_dev->name = MMC35240_DRV_NAME;
 512        indio_dev->channels = mmc35240_channels;
 513        indio_dev->num_channels = ARRAY_SIZE(mmc35240_channels);
 514        indio_dev->modes = INDIO_DIRECT_MODE;
 515
 516        ret = mmc35240_init(data);
 517        if (ret < 0) {
 518                dev_err(&client->dev, "mmc35240 chip init failed\n");
 519                return ret;
 520        }
 521        return devm_iio_device_register(&client->dev, indio_dev);
 522}
 523
 524#ifdef CONFIG_PM_SLEEP
 525static int mmc35240_suspend(struct device *dev)
 526{
 527        struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
 528        struct mmc35240_data *data = iio_priv(indio_dev);
 529
 530        regcache_cache_only(data->regmap, true);
 531
 532        return 0;
 533}
 534
 535static int mmc35240_resume(struct device *dev)
 536{
 537        struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
 538        struct mmc35240_data *data = iio_priv(indio_dev);
 539        int ret;
 540
 541        regcache_mark_dirty(data->regmap);
 542        ret = regcache_sync_region(data->regmap, MMC35240_REG_CTRL0,
 543                                   MMC35240_REG_CTRL1);
 544        if (ret < 0)
 545                dev_err(dev, "Failed to restore control registers\n");
 546
 547        regcache_cache_only(data->regmap, false);
 548
 549        return 0;
 550}
 551#endif
 552
 553static const struct dev_pm_ops mmc35240_pm_ops = {
 554        SET_SYSTEM_SLEEP_PM_OPS(mmc35240_suspend, mmc35240_resume)
 555};
 556
 557static const struct of_device_id mmc35240_of_match[] = {
 558        { .compatible = "memsic,mmc35240", },
 559        { }
 560};
 561MODULE_DEVICE_TABLE(of, mmc35240_of_match);
 562
 563static const struct acpi_device_id mmc35240_acpi_match[] = {
 564        {"MMC35240", 0},
 565        { },
 566};
 567MODULE_DEVICE_TABLE(acpi, mmc35240_acpi_match);
 568
 569static const struct i2c_device_id mmc35240_id[] = {
 570        {"mmc35240", 0},
 571        {}
 572};
 573MODULE_DEVICE_TABLE(i2c, mmc35240_id);
 574
 575static struct i2c_driver mmc35240_driver = {
 576        .driver = {
 577                .name = MMC35240_DRV_NAME,
 578                .of_match_table = mmc35240_of_match,
 579                .pm = &mmc35240_pm_ops,
 580                .acpi_match_table = ACPI_PTR(mmc35240_acpi_match),
 581        },
 582        .probe          = mmc35240_probe,
 583        .id_table       = mmc35240_id,
 584};
 585
 586module_i2c_driver(mmc35240_driver);
 587
 588MODULE_AUTHOR("Daniel Baluta <daniel.baluta@intel.com>");
 589MODULE_DESCRIPTION("MEMSIC MMC35240 magnetic sensor driver");
 590MODULE_LICENSE("GPL v2");
 591