drivers/iio/magnetometer/mmc35240.c

   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
  86 enum 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
  93 enum mmc35240_axis {
  94         AXIS_X = 0,
  95         AXIS_Y,
  96         AXIS_Z,
  97 };
  98
  99 static 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
 125 struct 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
 136 static const struct {
 137         int val;
 138         int val2;
 139 } mmc35240_samp_freq[] = { {1, 500000},
 140                            {13, 0},
 141                            {25, 0},
 142                            {50, 0} };
 143
 144 static 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
 156 static const struct iio_chan_spec mmc35240_channels[] = {
 157         MMC35240_CHANNEL(X),
 158         MMC35240_CHANNEL(Y),
 159         MMC35240_CHANNEL(Z),
 160 };
 161
 162 static struct attribute *mmc35240_attributes[] = {
 163         &iio_const_attr_sampling_frequency_available.dev_attr.attr,
 164         NULL
 165 };
 166
 167 static const struct attribute_group mmc35240_attribute_group = {
 168         .attrs = mmc35240_attributes,
 169 };
 170
 171 static 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
 183 static 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
 209 static 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
 264 static 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
 293 static 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  */
 316 static 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
 354 static 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
 397 static 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
 420 static 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
 426 static 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
 437 static 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
 454 static 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
 465 static struct reg_default mmc35240_reg_defaults[] = {
 466         { MMC35240_REG_CTRL0,  0x00 },
 467         { MMC35240_REG_CTRL1,  0x00 },
 468 };
 469
 470 static 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
 487 static 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
 529 static 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
 539 static 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
 557 static const struct dev_pm_ops mmc35240_pm_ops = {
 558         SET_SYSTEM_SLEEP_PM_OPS(mmc35240_suspend, mmc35240_resume)
 559 };
 560
 561 static const struct of_device_id mmc35240_of_match[] = {
 562         { .compatible = "memsic,mmc35240", },
 563         { }
 564 };
 565 MODULE_DEVICE_TABLE(of, mmc35240_of_match);
 566
 567 static const struct acpi_device_id mmc35240_acpi_match[] = {
 568         {"MMC35240", 0},
 569         { },
 570 };
 571 MODULE_DEVICE_TABLE(acpi, mmc35240_acpi_match);
 572
 573 static const struct i2c_device_id mmc35240_id[] = {
 574         {"mmc35240", 0},
 575         {}
 576 };
 577 MODULE_DEVICE_TABLE(i2c, mmc35240_id);
 578
 579 static 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
 590 module_i2c_driver(mmc35240_driver);
 591
 592 MODULE_AUTHOR("Daniel Baluta <daniel.baluta@intel.com>");
 593 MODULE_DESCRIPTION("MEMSIC MMC35240 magnetic sensor driver");
 594 MODULE_LICENSE("GPL v2");