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, /* 100 Hz */
  88         MMC35240_16_BITS_FAST,     /* 200 Hz */
  89         MMC35240_14_BITS,          /* 333 Hz */
  90         MMC35240_12_BITS,          /* 666 Hz */
  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, 100Hz ODR */
 104         {
 105                 {1024, 1024, 1024},
 106                 32768,
 107         },
 108         /* 16 bits, 200Hz ODR */
 109         {
 110                 {1024, 1024, 770},
 111                 32768,
 112         },
 113         /* 14 bits, 333Hz ODR */
 114         {
 115                 {256, 256, 193},
 116                 8192,
 117         },
 118         /* 12 bits, 666Hz 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 int mmc35240_samp_freq[] = {100, 200, 333, 666};
 137
 138 static IIO_CONST_ATTR_SAMP_FREQ_AVAIL("100 200 333 666");
 139
 140 #define MMC35240_CHANNEL(_axis) { \
 141         .type = IIO_MAGN, \
 142         .modified = 1, \
 143         .channel2 = IIO_MOD_ ## _axis, \
 144         .address = AXIS_ ## _axis, \
 145         .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
 146         .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SAMP_FREQ) | \
 147                         BIT(IIO_CHAN_INFO_SCALE), \
 148 }
 149
 150 static const struct iio_chan_spec mmc35240_channels[] = {
 151         MMC35240_CHANNEL(X),
 152         MMC35240_CHANNEL(Y),
 153         MMC35240_CHANNEL(Z),
 154 };
 155
 156 static struct attribute *mmc35240_attributes[] = {
 157         &iio_const_attr_sampling_frequency_available.dev_attr.attr,
 158         NULL
 159 };
 160
 161 static const struct attribute_group mmc35240_attribute_group = {
 162         .attrs = mmc35240_attributes,
 163 };
 164
 165 static int mmc35240_get_samp_freq_index(struct mmc35240_data *data,
 166                                         int val, int val2)
 167 {
 168         int i;
 169
 170         for (i = 0; i < ARRAY_SIZE(mmc35240_samp_freq); i++)
 171                 if (mmc35240_samp_freq[i] == val)
 172                         return i;
 173         return -EINVAL;
 174 }
 175
 176 static int mmc35240_hw_set(struct mmc35240_data *data, bool set)
 177 {
 178         int ret;
 179         u8 coil_bit;
 180
 181         /*
 182          * Recharge the capacitor at VCAP pin, requested to be issued
 183          * before a SET/RESET command.
 184          */
 185         ret = regmap_update_bits(data->regmap, MMC35240_REG_CTRL0,
 186                                  MMC35240_CTRL0_REFILL_BIT,
 187                                  MMC35240_CTRL0_REFILL_BIT);
 188         if (ret < 0)
 189                 return ret;
 190         usleep_range(MMC35240_WAIT_CHARGE_PUMP, MMC35240_WAIT_CHARGE_PUMP + 1);
 191
 192         if (set)
 193                 coil_bit = MMC35240_CTRL0_SET_BIT;
 194         else
 195                 coil_bit = MMC35240_CTRL0_RESET_BIT;
 196
 197         return regmap_update_bits(data->regmap, MMC35240_REG_CTRL0,
 198                                   MMC35240_CTRL0_REFILL_BIT,
 199                                   coil_bit);
 200 }
 201
 202 static int mmc35240_init(struct mmc35240_data *data)
 203 {
 204         int ret, y_convert, z_convert;
 205         unsigned int reg_id;
 206         u8 otp_data[6];
 207
 208         ret = regmap_read(data->regmap, MMC35240_REG_ID, &reg_id);
 209         if (ret < 0) {
 210                 dev_err(&data->client->dev, "Error reading product id\n");
 211                 return ret;
 212         }
 213
 214         dev_dbg(&data->client->dev, "MMC35240 chip id %x\n", reg_id);
 215
 216         /*
 217          * make sure we restore sensor characteristics, by doing
 218          * a RESET/SET sequence
 219          */
 220         ret = mmc35240_hw_set(data, false);
 221         if (ret < 0)
 222                 return ret;
 223         usleep_range(MMC53240_WAIT_SET_RESET, MMC53240_WAIT_SET_RESET + 1);
 224
 225         ret = mmc35240_hw_set(data, true);
 226         if (ret < 0)
 227                 return ret;
 228
 229         /* set default sampling frequency */
 230         ret = regmap_update_bits(data->regmap, MMC35240_REG_CTRL1,
 231                                  MMC35240_CTRL1_BW_MASK,
 232                                  data->res << MMC35240_CTRL1_BW_SHIFT);
 233         if (ret < 0)
 234                 return ret;
 235
 236         ret = regmap_bulk_read(data->regmap, MMC35240_OTP_START_ADDR,
 237                                (u8 *)otp_data, sizeof(otp_data));
 238         if (ret < 0)
 239                 return ret;
 240
 241         y_convert = MMC35240_OTP_CONVERT_Y(((otp_data[1] & 0x03) << 4) |
 242                                            (otp_data[2] >> 4));
 243         z_convert = MMC35240_OTP_CONVERT_Z(otp_data[3] & 0x3f);
 244
 245         data->axis_coef[0] = MMC35240_X_COEFF(1);
 246         data->axis_coef[1] = MMC35240_Y_COEFF(y_convert);
 247         data->axis_coef[2] = MMC35240_Z_COEFF(z_convert);
 248
 249         data->axis_scale[0] = 1;
 250         data->axis_scale[1] = 1000;
 251         data->axis_scale[2] = 10000;
 252
 253         return 0;
 254 }
 255
 256 static int mmc35240_take_measurement(struct mmc35240_data *data)
 257 {
 258         int ret, tries = 100;
 259         unsigned int reg_status;
 260
 261         ret = regmap_write(data->regmap, MMC35240_REG_CTRL0,
 262                            MMC35240_CTRL0_TM_BIT);
 263         if (ret < 0)
 264                 return ret;
 265
 266         while (tries-- > 0) {
 267                 ret = regmap_read(data->regmap, MMC35240_REG_STATUS,
 268                                   &reg_status);
 269                 if (ret < 0)
 270                         return ret;
 271                 if (reg_status & MMC35240_STATUS_MEAS_DONE_BIT)
 272                         break;
 273                 /* minimum wait time to complete measurement is 10 ms */
 274                 usleep_range(10000, 11000);
 275         }
 276
 277         if (tries < 0) {
 278                 dev_err(&data->client->dev, "data not ready\n");
 279                 return -EIO;
 280         }
 281
 282         return 0;
 283 }
 284
 285 static int mmc35240_read_measurement(struct mmc35240_data *data, __le16 buf[3])
 286 {
 287         int ret;
 288
 289         ret = mmc35240_take_measurement(data);
 290         if (ret < 0)
 291                 return ret;
 292
 293         return regmap_bulk_read(data->regmap, MMC35240_REG_XOUT_L, (u8 *)buf,
 294                                 3 * sizeof(__le16));
 295 }
 296
 297 /**
 298  * mmc35240_raw_to_mgauss - convert raw readings to milli gauss. Also apply
 299                             compensation for output value.
 300  *
 301  * @data: device private data
 302  * @index: axis index for which we want the conversion
 303  * @buf: raw data to be converted, 2 bytes in little endian format
 304  * @val: compensated output reading (unit is milli gauss)
 305  *
 306  * Returns: 0 in case of success, -EINVAL when @index is not valid
 307  */
 308 static int mmc35240_raw_to_mgauss(struct mmc35240_data *data, int index,
 309                                   __le16 buf[], int *val)
 310 {
 311         int raw_x, raw_y, raw_z;
 312         int sens_x, sens_y, sens_z;
 313         int nfo;
 314
 315         raw_x = le16_to_cpu(buf[AXIS_X]);
 316         raw_y = le16_to_cpu(buf[AXIS_Y]);
 317         raw_z = le16_to_cpu(buf[AXIS_Z]);
 318
 319         sens_x = mmc35240_props_table[data->res].sens[AXIS_X];
 320         sens_y = mmc35240_props_table[data->res].sens[AXIS_Y];
 321         sens_z = mmc35240_props_table[data->res].sens[AXIS_Z];
 322
 323         nfo = mmc35240_props_table[data->res].nfo;
 324
 325         switch (index) {
 326         case AXIS_X:
 327                 *val = (raw_x - nfo) * 1000 / sens_x;
 328                 break;
 329         case AXIS_Y:
 330                 *val = (raw_y - nfo) * 1000 / sens_y -
 331                         (raw_z - nfo)  * 1000 / sens_z;
 332                 break;
 333         case AXIS_Z:
 334                 *val = (raw_y - nfo) * 1000 / sens_y +
 335                         (raw_z - nfo) * 1000 / sens_z;
 336                 break;
 337         default:
 338                 return -EINVAL;
 339         }
 340         /* apply OTP compensation */
 341         *val = (*val) * data->axis_coef[index] / data->axis_scale[index];
 342
 343         return 0;
 344 }
 345
 346 static int mmc35240_read_raw(struct iio_dev *indio_dev,
 347                              struct iio_chan_spec const *chan, int *val,
 348                              int *val2, long mask)
 349 {
 350         struct mmc35240_data *data = iio_priv(indio_dev);
 351         int ret, i;
 352         unsigned int reg;
 353         __le16 buf[3];
 354
 355         switch (mask) {
 356         case IIO_CHAN_INFO_RAW:
 357                 mutex_lock(&data->mutex);
 358                 ret = mmc35240_read_measurement(data, buf);
 359                 mutex_unlock(&data->mutex);
 360                 if (ret < 0)
 361                         return ret;
 362                 ret = mmc35240_raw_to_mgauss(data, chan->address, buf, val);
 363                 if (ret < 0)
 364                         return ret;
 365                 return IIO_VAL_INT;
 366         case IIO_CHAN_INFO_SCALE:
 367                 *val = 0;
 368                 *val2 = 1000;
 369                 return IIO_VAL_INT_PLUS_MICRO;
 370         case IIO_CHAN_INFO_SAMP_FREQ:
 371                 mutex_lock(&data->mutex);
 372                 ret = regmap_read(data->regmap, MMC35240_REG_CTRL1, &reg);
 373                 mutex_unlock(&data->mutex);
 374                 if (ret < 0)
 375                         return ret;
 376
 377                 i = (reg & MMC35240_CTRL1_BW_MASK) >> MMC35240_CTRL1_BW_SHIFT;
 378                 if (i < 0 || i >= ARRAY_SIZE(mmc35240_samp_freq))
 379                         return -EINVAL;
 380
 381                 *val = mmc35240_samp_freq[i];
 382                 *val2 = 0;
 383                 return IIO_VAL_INT;
 384         default:
 385                 return -EINVAL;
 386         }
 387 }
 388
 389 static int mmc35240_write_raw(struct iio_dev *indio_dev,
 390                               struct iio_chan_spec const *chan, int val,
 391                               int val2, long mask)
 392 {
 393         struct mmc35240_data *data = iio_priv(indio_dev);
 394         int i, ret;
 395
 396         switch (mask) {
 397         case IIO_CHAN_INFO_SAMP_FREQ:
 398                 i = mmc35240_get_samp_freq_index(data, val, val2);
 399                 if (i < 0)
 400                         return -EINVAL;
 401                 mutex_lock(&data->mutex);
 402                 ret = regmap_update_bits(data->regmap, MMC35240_REG_CTRL1,
 403                                          MMC35240_CTRL1_BW_MASK,
 404                                          i << MMC35240_CTRL1_BW_SHIFT);
 405                 mutex_unlock(&data->mutex);
 406                 return ret;
 407         default:
 408                 return -EINVAL;
 409         }
 410 }
 411
 412 static const struct iio_info mmc35240_info = {
 413         .driver_module  = THIS_MODULE,
 414         .read_raw       = mmc35240_read_raw,
 415         .write_raw      = mmc35240_write_raw,
 416         .attrs          = &mmc35240_attribute_group,
 417 };
 418
 419 static bool mmc35240_is_writeable_reg(struct device *dev, unsigned int reg)
 420 {
 421         switch (reg) {
 422         case MMC35240_REG_CTRL0:
 423         case MMC35240_REG_CTRL1:
 424                 return true;
 425         default:
 426                 return false;
 427         }
 428 }
 429
 430 static bool mmc35240_is_readable_reg(struct device *dev, unsigned int reg)
 431 {
 432         switch (reg) {
 433         case MMC35240_REG_XOUT_L:
 434         case MMC35240_REG_XOUT_H:
 435         case MMC35240_REG_YOUT_L:
 436         case MMC35240_REG_YOUT_H:
 437         case MMC35240_REG_ZOUT_L:
 438         case MMC35240_REG_ZOUT_H:
 439         case MMC35240_REG_STATUS:
 440         case MMC35240_REG_ID:
 441                 return true;
 442         default:
 443                 return false;
 444         }
 445 }
 446
 447 static bool mmc35240_is_volatile_reg(struct device *dev, unsigned int reg)
 448 {
 449         switch (reg) {
 450         case MMC35240_REG_CTRL0:
 451         case MMC35240_REG_CTRL1:
 452                 return false;
 453         default:
 454                 return true;
 455         }
 456 }
 457
 458 static struct reg_default mmc35240_reg_defaults[] = {
 459         { MMC35240_REG_CTRL0,  0x00 },
 460         { MMC35240_REG_CTRL1,  0x00 },
 461 };
 462
 463 static const struct regmap_config mmc35240_regmap_config = {
 464         .name = MMC35240_REGMAP_NAME,
 465
 466         .reg_bits = 8,
 467         .val_bits = 8,
 468
 469         .max_register = MMC35240_REG_ID,
 470         .cache_type = REGCACHE_FLAT,
 471
 472         .writeable_reg = mmc35240_is_writeable_reg,
 473         .readable_reg = mmc35240_is_readable_reg,
 474         .volatile_reg = mmc35240_is_volatile_reg,
 475
 476         .reg_defaults = mmc35240_reg_defaults,
 477         .num_reg_defaults = ARRAY_SIZE(mmc35240_reg_defaults),
 478 };
 479
 480 static int mmc35240_probe(struct i2c_client *client,
 481                           const struct i2c_device_id *id)
 482 {
 483         struct mmc35240_data *data;
 484         struct iio_dev *indio_dev;
 485         struct regmap *regmap;
 486         int ret;
 487
 488         indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
 489         if (!indio_dev)
 490                 return -ENOMEM;
 491
 492         regmap = devm_regmap_init_i2c(client, &mmc35240_regmap_config);
 493         if (IS_ERR(regmap)) {
 494                 dev_err(&client->dev, "regmap initialization failed\n");
 495                 return PTR_ERR(regmap);
 496         }
 497
 498         data = iio_priv(indio_dev);
 499         data->client = client;
 500         data->regmap = regmap;
 501         data->res = MMC35240_16_BITS_SLOW;
 502
 503         mutex_init(&data->mutex);
 504
 505         indio_dev->dev.parent = &client->dev;
 506         indio_dev->info = &mmc35240_info;
 507         indio_dev->name = MMC35240_DRV_NAME;
 508         indio_dev->channels = mmc35240_channels;
 509         indio_dev->num_channels = ARRAY_SIZE(mmc35240_channels);
 510         indio_dev->modes = INDIO_DIRECT_MODE;
 511
 512         ret = mmc35240_init(data);
 513         if (ret < 0) {
 514                 dev_err(&client->dev, "mmc35240 chip init failed\n");
 515                 return ret;
 516         }
 517         return devm_iio_device_register(&client->dev, indio_dev);
 518 }
 519
 520 #ifdef CONFIG_PM_SLEEP
 521 static int mmc35240_suspend(struct device *dev)
 522 {
 523         struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
 524         struct mmc35240_data *data = iio_priv(indio_dev);
 525
 526         regcache_cache_only(data->regmap, true);
 527
 528         return 0;
 529 }
 530
 531 static int mmc35240_resume(struct device *dev)
 532 {
 533         struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
 534         struct mmc35240_data *data = iio_priv(indio_dev);
 535         int ret;
 536
 537         regcache_mark_dirty(data->regmap);
 538         ret = regcache_sync_region(data->regmap, MMC35240_REG_CTRL0,
 539                                    MMC35240_REG_CTRL1);
 540         if (ret < 0)
 541                 dev_err(dev, "Failed to restore control registers\n");
 542
 543         regcache_cache_only(data->regmap, false);
 544
 545         return 0;
 546 }
 547 #endif
 548
 549 static const struct dev_pm_ops mmc35240_pm_ops = {
 550         SET_SYSTEM_SLEEP_PM_OPS(mmc35240_suspend, mmc35240_resume)
 551 };
 552
 553 static const struct acpi_device_id mmc35240_acpi_match[] = {
 554         {"MMC35240", 0},
 555         { },
 556 };
 557 MODULE_DEVICE_TABLE(acpi, mmc35240_acpi_match);
 558
 559 static const struct i2c_device_id mmc35240_id[] = {
 560         {"mmc35240", 0},
 561         {}
 562 };
 563 MODULE_DEVICE_TABLE(i2c, mmc35240_id);
 564
 565 static struct i2c_driver mmc35240_driver = {
 566         .driver = {
 567                 .name = MMC35240_DRV_NAME,
 568                 .pm = &mmc35240_pm_ops,
 569                 .acpi_match_table = ACPI_PTR(mmc35240_acpi_match),
 570         },
 571         .probe          = mmc35240_probe,
 572         .id_table       = mmc35240_id,
 573 };
 574
 575 module_i2c_driver(mmc35240_driver);
 576
 577 MODULE_AUTHOR("Daniel Baluta <daniel.baluta@intel.com>");
 578 MODULE_DESCRIPTION("MEMSIC MMC35240 magnetic sensor driver");
 579 MODULE_LICENSE("GPL v2");