linux/drivers/iio/magnetometer/mmc35240.c
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   1/*
   2 * MMC35240 - MEMSIC 3-axis Magnetic Sensor
   3 *
   4 * Copyright (c) 2015, Intel Corporation.
   5 *
   6 * This file is subject to the terms and conditions of version 2 of
   7 * the GNU General Public License.  See the file COPYING in the main
   8 * directory of this archive for more details.
   9 *
  10 * IIO driver for MMC35240 (7-bit I2C slave address 0x30).
  11 *
  12 * TODO: offset, ACPI, continuous measurement mode, PM
  13 */
  14
  15#include <linux/module.h>
  16#include <linux/init.h>
  17#include <linux/i2c.h>
  18#include <linux/delay.h>
  19#include <linux/regmap.h>
  20#include <linux/acpi.h>
  21#include <linux/pm.h>
  22
  23#include <linux/iio/iio.h>
  24#include <linux/iio/sysfs.h>
  25
  26#define MMC35240_DRV_NAME "mmc35240"
  27#define MMC35240_REGMAP_NAME "mmc35240_regmap"
  28
  29#define MMC35240_REG_XOUT_L     0x00
  30#define MMC35240_REG_XOUT_H     0x01
  31#define MMC35240_REG_YOUT_L     0x02
  32#define MMC35240_REG_YOUT_H     0x03
  33#define MMC35240_REG_ZOUT_L     0x04
  34#define MMC35240_REG_ZOUT_H     0x05
  35
  36#define MMC35240_REG_STATUS     0x06
  37#define MMC35240_REG_CTRL0      0x07
  38#define MMC35240_REG_CTRL1      0x08
  39
  40#define MMC35240_REG_ID         0x20
  41
  42#define MMC35240_STATUS_MEAS_DONE_BIT   BIT(0)
  43
  44#define MMC35240_CTRL0_REFILL_BIT       BIT(7)
  45#define MMC35240_CTRL0_RESET_BIT        BIT(6)
  46#define MMC35240_CTRL0_SET_BIT          BIT(5)
  47#define MMC35240_CTRL0_CMM_BIT          BIT(1)
  48#define MMC35240_CTRL0_TM_BIT           BIT(0)
  49
  50/* output resolution bits */
  51#define MMC35240_CTRL1_BW0_BIT          BIT(0)
  52#define MMC35240_CTRL1_BW1_BIT          BIT(1)
  53
  54#define MMC35240_CTRL1_BW_MASK   (MMC35240_CTRL1_BW0_BIT | \
  55                 MMC35240_CTRL1_BW1_BIT)
  56#define MMC35240_CTRL1_BW_SHIFT         0
  57
  58#define MMC35240_WAIT_CHARGE_PUMP       50000   /* us */
  59#define MMC53240_WAIT_SET_RESET         1000    /* us */
  60
  61/*
  62 * Memsic OTP process code piece is put here for reference:
  63 *
  64 * #define OTP_CONVERT(REG)  ((float)((REG) >=32 ? (32 - (REG)) : (REG)) * 0.006
  65 * 1) For X axis, the COEFFICIENT is always 1.
  66 * 2) For Y axis, the COEFFICIENT is as below:
  67 *    f_OTP_matrix[4] = OTP_CONVERT(((reg_data[1] & 0x03) << 4) |
  68 *                                   (reg_data[2] >> 4)) + 1.0;
  69 * 3) For Z axis, the COEFFICIENT is as below:
  70 *    f_OTP_matrix[8] = (OTP_CONVERT(reg_data[3] & 0x3f) + 1) * 1.35;
  71 * We implemented the OTP logic into driver.
  72 */
  73
  74/* scale = 1000 here for Y otp */
  75#define MMC35240_OTP_CONVERT_Y(REG) (((REG) >= 32 ? (32 - (REG)) : (REG)) * 6)
  76
  77/* 0.6 * 1.35 = 0.81, scale 10000 for Z otp */
  78#define MMC35240_OTP_CONVERT_Z(REG) (((REG) >= 32 ? (32 - (REG)) : (REG)) * 81)
  79
  80#define MMC35240_X_COEFF(x)     (x)
  81#define MMC35240_Y_COEFF(y)     (y + 1000)
  82#define MMC35240_Z_COEFF(z)     (z + 13500)
  83
  84#define MMC35240_OTP_START_ADDR         0x1B
  85
  86enum mmc35240_resolution {
  87        MMC35240_16_BITS_SLOW = 0, /* 7.92 ms */
  88        MMC35240_16_BITS_FAST,     /* 4.08 ms */
  89        MMC35240_14_BITS,          /* 2.16 ms */
  90        MMC35240_12_BITS,          /* 1.20 ms */
  91};
  92
  93enum mmc35240_axis {
  94        AXIS_X = 0,
  95        AXIS_Y,
  96        AXIS_Z,
  97};
  98
  99static const struct {
 100        int sens[3]; /* sensitivity per X, Y, Z axis */
 101        int nfo; /* null field output */
 102} mmc35240_props_table[] = {
 103        /* 16 bits, 125Hz ODR */
 104        {
 105                {1024, 1024, 1024},
 106                32768,
 107        },
 108        /* 16 bits, 250Hz ODR */
 109        {
 110                {1024, 1024, 770},
 111                32768,
 112        },
 113        /* 14 bits, 450Hz ODR */
 114        {
 115                {256, 256, 193},
 116                8192,
 117        },
 118        /* 12 bits, 800Hz ODR */
 119        {
 120                {64, 64, 48},
 121                2048,
 122        },
 123};
 124
 125struct mmc35240_data {
 126        struct i2c_client *client;
 127        struct mutex mutex;
 128        struct regmap *regmap;
 129        enum mmc35240_resolution res;
 130
 131        /* OTP compensation */
 132        int axis_coef[3];
 133        int axis_scale[3];
 134};
 135
 136static const struct {
 137        int val;
 138        int val2;
 139} mmc35240_samp_freq[] = { {1, 500000},
 140                           {13, 0},
 141                           {25, 0},
 142                           {50, 0} };
 143
 144static IIO_CONST_ATTR_SAMP_FREQ_AVAIL("1.5 13 25 50");
 145
 146#define MMC35240_CHANNEL(_axis) { \
 147        .type = IIO_MAGN, \
 148        .modified = 1, \
 149        .channel2 = IIO_MOD_ ## _axis, \
 150        .address = AXIS_ ## _axis, \
 151        .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
 152        .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SAMP_FREQ) | \
 153                        BIT(IIO_CHAN_INFO_SCALE), \
 154}
 155
 156static const struct iio_chan_spec mmc35240_channels[] = {
 157        MMC35240_CHANNEL(X),
 158        MMC35240_CHANNEL(Y),
 159        MMC35240_CHANNEL(Z),
 160};
 161
 162static struct attribute *mmc35240_attributes[] = {
 163        &iio_const_attr_sampling_frequency_available.dev_attr.attr,
 164        NULL
 165};
 166
 167static const struct attribute_group mmc35240_attribute_group = {
 168        .attrs = mmc35240_attributes,
 169};
 170
 171static int mmc35240_get_samp_freq_index(struct mmc35240_data *data,
 172                                        int val, int val2)
 173{
 174        int i;
 175
 176        for (i = 0; i < ARRAY_SIZE(mmc35240_samp_freq); i++)
 177                if (mmc35240_samp_freq[i].val == val &&
 178                    mmc35240_samp_freq[i].val2 == val2)
 179                        return i;
 180        return -EINVAL;
 181}
 182
 183static int mmc35240_hw_set(struct mmc35240_data *data, bool set)
 184{
 185        int ret;
 186        u8 coil_bit;
 187
 188        /*
 189         * Recharge the capacitor at VCAP pin, requested to be issued
 190         * before a SET/RESET command.
 191         */
 192        ret = regmap_update_bits(data->regmap, MMC35240_REG_CTRL0,
 193                                 MMC35240_CTRL0_REFILL_BIT,
 194                                 MMC35240_CTRL0_REFILL_BIT);
 195        if (ret < 0)
 196                return ret;
 197        usleep_range(MMC35240_WAIT_CHARGE_PUMP, MMC35240_WAIT_CHARGE_PUMP + 1);
 198
 199        if (set)
 200                coil_bit = MMC35240_CTRL0_SET_BIT;
 201        else
 202                coil_bit = MMC35240_CTRL0_RESET_BIT;
 203
 204        return regmap_update_bits(data->regmap, MMC35240_REG_CTRL0,
 205                                  coil_bit, coil_bit);
 206
 207}
 208
 209static int mmc35240_init(struct mmc35240_data *data)
 210{
 211        int ret, y_convert, z_convert;
 212        unsigned int reg_id;
 213        u8 otp_data[6];
 214
 215        ret = regmap_read(data->regmap, MMC35240_REG_ID, &reg_id);
 216        if (ret < 0) {
 217                dev_err(&data->client->dev, "Error reading product id\n");
 218                return ret;
 219        }
 220
 221        dev_dbg(&data->client->dev, "MMC35240 chip id %x\n", reg_id);
 222
 223        /*
 224         * make sure we restore sensor characteristics, by doing
 225         * a SET/RESET sequence, the axis polarity being naturally
 226         * aligned after RESET
 227         */
 228        ret = mmc35240_hw_set(data, true);
 229        if (ret < 0)
 230                return ret;
 231        usleep_range(MMC53240_WAIT_SET_RESET, MMC53240_WAIT_SET_RESET + 1);
 232
 233        ret = mmc35240_hw_set(data, false);
 234        if (ret < 0)
 235                return ret;
 236
 237        /* set default sampling frequency */
 238        ret = regmap_update_bits(data->regmap, MMC35240_REG_CTRL1,
 239                                 MMC35240_CTRL1_BW_MASK,
 240                                 data->res << MMC35240_CTRL1_BW_SHIFT);
 241        if (ret < 0)
 242                return ret;
 243
 244        ret = regmap_bulk_read(data->regmap, MMC35240_OTP_START_ADDR,
 245                               (u8 *)otp_data, sizeof(otp_data));
 246        if (ret < 0)
 247                return ret;
 248
 249        y_convert = MMC35240_OTP_CONVERT_Y(((otp_data[1] & 0x03) << 4) |
 250                                           (otp_data[2] >> 4));
 251        z_convert = MMC35240_OTP_CONVERT_Z(otp_data[3] & 0x3f);
 252
 253        data->axis_coef[0] = MMC35240_X_COEFF(1);
 254        data->axis_coef[1] = MMC35240_Y_COEFF(y_convert);
 255        data->axis_coef[2] = MMC35240_Z_COEFF(z_convert);
 256
 257        data->axis_scale[0] = 1;
 258        data->axis_scale[1] = 1000;
 259        data->axis_scale[2] = 10000;
 260
 261        return 0;
 262}
 263
 264static int mmc35240_take_measurement(struct mmc35240_data *data)
 265{
 266        int ret, tries = 100;
 267        unsigned int reg_status;
 268
 269        ret = regmap_write(data->regmap, MMC35240_REG_CTRL0,
 270                           MMC35240_CTRL0_TM_BIT);
 271        if (ret < 0)
 272                return ret;
 273
 274        while (tries-- > 0) {
 275                ret = regmap_read(data->regmap, MMC35240_REG_STATUS,
 276                                  &reg_status);
 277                if (ret < 0)
 278                        return ret;
 279                if (reg_status & MMC35240_STATUS_MEAS_DONE_BIT)
 280                        break;
 281                /* minimum wait time to complete measurement is 10 ms */
 282                usleep_range(10000, 11000);
 283        }
 284
 285        if (tries < 0) {
 286                dev_err(&data->client->dev, "data not ready\n");
 287                return -EIO;
 288        }
 289
 290        return 0;
 291}
 292
 293static int mmc35240_read_measurement(struct mmc35240_data *data, __le16 buf[3])
 294{
 295        int ret;
 296
 297        ret = mmc35240_take_measurement(data);
 298        if (ret < 0)
 299                return ret;
 300
 301        return regmap_bulk_read(data->regmap, MMC35240_REG_XOUT_L, (u8 *)buf,
 302                                3 * sizeof(__le16));
 303}
 304
 305/**
 306 * mmc35240_raw_to_mgauss - convert raw readings to milli gauss. Also apply
 307                            compensation for output value.
 308 *
 309 * @data: device private data
 310 * @index: axis index for which we want the conversion
 311 * @buf: raw data to be converted, 2 bytes in little endian format
 312 * @val: compensated output reading (unit is milli gauss)
 313 *
 314 * Returns: 0 in case of success, -EINVAL when @index is not valid
 315 */
 316static int mmc35240_raw_to_mgauss(struct mmc35240_data *data, int index,
 317                                  __le16 buf[], int *val)
 318{
 319        int raw[3];
 320        int sens[3];
 321        int nfo;
 322
 323        raw[AXIS_X] = le16_to_cpu(buf[AXIS_X]);
 324        raw[AXIS_Y] = le16_to_cpu(buf[AXIS_Y]);
 325        raw[AXIS_Z] = le16_to_cpu(buf[AXIS_Z]);
 326
 327        sens[AXIS_X] = mmc35240_props_table[data->res].sens[AXIS_X];
 328        sens[AXIS_Y] = mmc35240_props_table[data->res].sens[AXIS_Y];
 329        sens[AXIS_Z] = mmc35240_props_table[data->res].sens[AXIS_Z];
 330
 331        nfo = mmc35240_props_table[data->res].nfo;
 332
 333        switch (index) {
 334        case AXIS_X:
 335                *val = (raw[AXIS_X] - nfo) * 1000 / sens[AXIS_X];
 336                break;
 337        case AXIS_Y:
 338                *val = (raw[AXIS_Y] - nfo) * 1000 / sens[AXIS_Y] -
 339                        (raw[AXIS_Z] - nfo)  * 1000 / sens[AXIS_Z];
 340                break;
 341        case AXIS_Z:
 342                *val = (raw[AXIS_Y] - nfo) * 1000 / sens[AXIS_Y] +
 343                        (raw[AXIS_Z] - nfo) * 1000 / sens[AXIS_Z];
 344                break;
 345        default:
 346                return -EINVAL;
 347        }
 348        /* apply OTP compensation */
 349        *val = (*val) * data->axis_coef[index] / data->axis_scale[index];
 350
 351        return 0;
 352}
 353
 354static int mmc35240_read_raw(struct iio_dev *indio_dev,
 355                             struct iio_chan_spec const *chan, int *val,
 356                             int *val2, long mask)
 357{
 358        struct mmc35240_data *data = iio_priv(indio_dev);
 359        int ret, i;
 360        unsigned int reg;
 361        __le16 buf[3];
 362
 363        switch (mask) {
 364        case IIO_CHAN_INFO_RAW:
 365                mutex_lock(&data->mutex);
 366                ret = mmc35240_read_measurement(data, buf);
 367                mutex_unlock(&data->mutex);
 368                if (ret < 0)
 369                        return ret;
 370                ret = mmc35240_raw_to_mgauss(data, chan->address, buf, val);
 371                if (ret < 0)
 372                        return ret;
 373                return IIO_VAL_INT;
 374        case IIO_CHAN_INFO_SCALE:
 375                *val = 0;
 376                *val2 = 1000;
 377                return IIO_VAL_INT_PLUS_MICRO;
 378        case IIO_CHAN_INFO_SAMP_FREQ:
 379                mutex_lock(&data->mutex);
 380                ret = regmap_read(data->regmap, MMC35240_REG_CTRL1, &reg);
 381                mutex_unlock(&data->mutex);
 382                if (ret < 0)
 383                        return ret;
 384
 385                i = (reg & MMC35240_CTRL1_BW_MASK) >> MMC35240_CTRL1_BW_SHIFT;
 386                if (i < 0 || i >= ARRAY_SIZE(mmc35240_samp_freq))
 387                        return -EINVAL;
 388
 389                *val = mmc35240_samp_freq[i].val;
 390                *val2 = mmc35240_samp_freq[i].val2;
 391                return IIO_VAL_INT_PLUS_MICRO;
 392        default:
 393                return -EINVAL;
 394        }
 395}
 396
 397static int mmc35240_write_raw(struct iio_dev *indio_dev,
 398                              struct iio_chan_spec const *chan, int val,
 399                              int val2, long mask)
 400{
 401        struct mmc35240_data *data = iio_priv(indio_dev);
 402        int i, ret;
 403
 404        switch (mask) {
 405        case IIO_CHAN_INFO_SAMP_FREQ:
 406                i = mmc35240_get_samp_freq_index(data, val, val2);
 407                if (i < 0)
 408                        return -EINVAL;
 409                mutex_lock(&data->mutex);
 410                ret = regmap_update_bits(data->regmap, MMC35240_REG_CTRL1,
 411                                         MMC35240_CTRL1_BW_MASK,
 412                                         i << MMC35240_CTRL1_BW_SHIFT);
 413                mutex_unlock(&data->mutex);
 414                return ret;
 415        default:
 416                return -EINVAL;
 417        }
 418}
 419
 420static const struct iio_info mmc35240_info = {
 421        .read_raw       = mmc35240_read_raw,
 422        .write_raw      = mmc35240_write_raw,
 423        .attrs          = &mmc35240_attribute_group,
 424};
 425
 426static bool mmc35240_is_writeable_reg(struct device *dev, unsigned int reg)
 427{
 428        switch (reg) {
 429        case MMC35240_REG_CTRL0:
 430        case MMC35240_REG_CTRL1:
 431                return true;
 432        default:
 433                return false;
 434        }
 435}
 436
 437static bool mmc35240_is_readable_reg(struct device *dev, unsigned int reg)
 438{
 439        switch (reg) {
 440        case MMC35240_REG_XOUT_L:
 441        case MMC35240_REG_XOUT_H:
 442        case MMC35240_REG_YOUT_L:
 443        case MMC35240_REG_YOUT_H:
 444        case MMC35240_REG_ZOUT_L:
 445        case MMC35240_REG_ZOUT_H:
 446        case MMC35240_REG_STATUS:
 447        case MMC35240_REG_ID:
 448                return true;
 449        default:
 450                return false;
 451        }
 452}
 453
 454static bool mmc35240_is_volatile_reg(struct device *dev, unsigned int reg)
 455{
 456        switch (reg) {
 457        case MMC35240_REG_CTRL0:
 458        case MMC35240_REG_CTRL1:
 459                return false;
 460        default:
 461                return true;
 462        }
 463}
 464
 465static struct reg_default mmc35240_reg_defaults[] = {
 466        { MMC35240_REG_CTRL0,  0x00 },
 467        { MMC35240_REG_CTRL1,  0x00 },
 468};
 469
 470static const struct regmap_config mmc35240_regmap_config = {
 471        .name = MMC35240_REGMAP_NAME,
 472
 473        .reg_bits = 8,
 474        .val_bits = 8,
 475
 476        .max_register = MMC35240_REG_ID,
 477        .cache_type = REGCACHE_FLAT,
 478
 479        .writeable_reg = mmc35240_is_writeable_reg,
 480        .readable_reg = mmc35240_is_readable_reg,
 481        .volatile_reg = mmc35240_is_volatile_reg,
 482
 483        .reg_defaults = mmc35240_reg_defaults,
 484        .num_reg_defaults = ARRAY_SIZE(mmc35240_reg_defaults),
 485};
 486
 487static int mmc35240_probe(struct i2c_client *client,
 488                          const struct i2c_device_id *id)
 489{
 490        struct mmc35240_data *data;
 491        struct iio_dev *indio_dev;
 492        struct regmap *regmap;
 493        int ret;
 494
 495        indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
 496        if (!indio_dev)
 497                return -ENOMEM;
 498
 499        regmap = devm_regmap_init_i2c(client, &mmc35240_regmap_config);
 500        if (IS_ERR(regmap)) {
 501                dev_err(&client->dev, "regmap initialization failed\n");
 502                return PTR_ERR(regmap);
 503        }
 504
 505        data = iio_priv(indio_dev);
 506        i2c_set_clientdata(client, indio_dev);
 507        data->client = client;
 508        data->regmap = regmap;
 509        data->res = MMC35240_16_BITS_SLOW;
 510
 511        mutex_init(&data->mutex);
 512
 513        indio_dev->dev.parent = &client->dev;
 514        indio_dev->info = &mmc35240_info;
 515        indio_dev->name = MMC35240_DRV_NAME;
 516        indio_dev->channels = mmc35240_channels;
 517        indio_dev->num_channels = ARRAY_SIZE(mmc35240_channels);
 518        indio_dev->modes = INDIO_DIRECT_MODE;
 519
 520        ret = mmc35240_init(data);
 521        if (ret < 0) {
 522                dev_err(&client->dev, "mmc35240 chip init failed\n");
 523                return ret;
 524        }
 525        return devm_iio_device_register(&client->dev, indio_dev);
 526}
 527
 528#ifdef CONFIG_PM_SLEEP
 529static int mmc35240_suspend(struct device *dev)
 530{
 531        struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
 532        struct mmc35240_data *data = iio_priv(indio_dev);
 533
 534        regcache_cache_only(data->regmap, true);
 535
 536        return 0;
 537}
 538
 539static int mmc35240_resume(struct device *dev)
 540{
 541        struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
 542        struct mmc35240_data *data = iio_priv(indio_dev);
 543        int ret;
 544
 545        regcache_mark_dirty(data->regmap);
 546        ret = regcache_sync_region(data->regmap, MMC35240_REG_CTRL0,
 547                                   MMC35240_REG_CTRL1);
 548        if (ret < 0)
 549                dev_err(dev, "Failed to restore control registers\n");
 550
 551        regcache_cache_only(data->regmap, false);
 552
 553        return 0;
 554}
 555#endif
 556
 557static const struct dev_pm_ops mmc35240_pm_ops = {
 558        SET_SYSTEM_SLEEP_PM_OPS(mmc35240_suspend, mmc35240_resume)
 559};
 560
 561static const struct of_device_id mmc35240_of_match[] = {
 562        { .compatible = "memsic,mmc35240", },
 563        { }
 564};
 565MODULE_DEVICE_TABLE(of, mmc35240_of_match);
 566
 567static const struct acpi_device_id mmc35240_acpi_match[] = {
 568        {"MMC35240", 0},
 569        { },
 570};
 571MODULE_DEVICE_TABLE(acpi, mmc35240_acpi_match);
 572
 573static const struct i2c_device_id mmc35240_id[] = {
 574        {"mmc35240", 0},
 575        {}
 576};
 577MODULE_DEVICE_TABLE(i2c, mmc35240_id);
 578
 579static struct i2c_driver mmc35240_driver = {
 580        .driver = {
 581                .name = MMC35240_DRV_NAME,
 582                .of_match_table = mmc35240_of_match,
 583                .pm = &mmc35240_pm_ops,
 584                .acpi_match_table = ACPI_PTR(mmc35240_acpi_match),
 585        },
 586        .probe          = mmc35240_probe,
 587        .id_table       = mmc35240_id,
 588};
 589
 590module_i2c_driver(mmc35240_driver);
 591
 592MODULE_AUTHOR("Daniel Baluta <daniel.baluta@intel.com>");
 593MODULE_DESCRIPTION("MEMSIC MMC35240 magnetic sensor driver");
 594MODULE_LICENSE("GPL v2");
 595