drivers/iio/magnetometer/mmc35240.c

/* [<][>][^][v][top][bottom][index][help] */
This source file includes following definitions.
mmc35240_get_samp_freq_index
mmc35240_hw_set
mmc35240_init
mmc35240_take_measurement
mmc35240_read_measurement
mmc35240_raw_to_mgauss
mmc35240_read_raw
mmc35240_write_raw
mmc35240_is_writeable_reg
mmc35240_is_readable_reg
mmc35240_is_volatile_reg
mmc35240_probe
mmc35240_suspend
mmc35240_resume
   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 
  83 enum 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 
  90 enum mmc35240_axis {
  91         AXIS_X = 0,
  92         AXIS_Y,
  93         AXIS_Z,
  94 };
  95 
  96 static 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 
 122 struct 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 
 133 static const struct {
 134         int val;
 135         int val2;
 136 } mmc35240_samp_freq[] = { {1, 500000},
 137                            {13, 0},
 138                            {25, 0},
 139                            {50, 0} };
 140 
 141 static 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 
 153 static const struct iio_chan_spec mmc35240_channels[] = {
 154         MMC35240_CHANNEL(X),
 155         MMC35240_CHANNEL(Y),
 156         MMC35240_CHANNEL(Z),
 157 };
 158 
 159 static struct attribute *mmc35240_attributes[] = {
 160         &iio_const_attr_sampling_frequency_available.dev_attr.attr,
 161         NULL
 162 };
 163 
 164 static const struct attribute_group mmc35240_attribute_group = {
 165         .attrs = mmc35240_attributes,
 166 };
 167 
 168 static 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 
 180 static 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 
 206 static 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                                (u8 *)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 
 261 static 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 
 290 static 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, (u8 *)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  */
 313 static 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 
 351 static 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 
 394 static 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 
 417 static 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 
 423 static 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 
 434 static 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 
 451 static 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 
 462 static struct reg_default mmc35240_reg_defaults[] = {
 463         { MMC35240_REG_CTRL0,  0x00 },
 464         { MMC35240_REG_CTRL1,  0x00 },
 465 };
 466 
 467 static 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 
 484 static 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->dev.parent = &client->dev;
 511         indio_dev->info = &mmc35240_info;
 512         indio_dev->name = MMC35240_DRV_NAME;
 513         indio_dev->channels = mmc35240_channels;
 514         indio_dev->num_channels = ARRAY_SIZE(mmc35240_channels);
 515         indio_dev->modes = INDIO_DIRECT_MODE;
 516 
 517         ret = mmc35240_init(data);
 518         if (ret < 0) {
 519                 dev_err(&client->dev, "mmc35240 chip init failed\n");
 520                 return ret;
 521         }
 522         return devm_iio_device_register(&client->dev, indio_dev);
 523 }
 524 
 525 #ifdef CONFIG_PM_SLEEP
 526 static int mmc35240_suspend(struct device *dev)
 527 {
 528         struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
 529         struct mmc35240_data *data = iio_priv(indio_dev);
 530 
 531         regcache_cache_only(data->regmap, true);
 532 
 533         return 0;
 534 }
 535 
 536 static int mmc35240_resume(struct device *dev)
 537 {
 538         struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
 539         struct mmc35240_data *data = iio_priv(indio_dev);
 540         int ret;
 541 
 542         regcache_mark_dirty(data->regmap);
 543         ret = regcache_sync_region(data->regmap, MMC35240_REG_CTRL0,
 544                                    MMC35240_REG_CTRL1);
 545         if (ret < 0)
 546                 dev_err(dev, "Failed to restore control registers\n");
 547 
 548         regcache_cache_only(data->regmap, false);
 549 
 550         return 0;
 551 }
 552 #endif
 553 
 554 static const struct dev_pm_ops mmc35240_pm_ops = {
 555         SET_SYSTEM_SLEEP_PM_OPS(mmc35240_suspend, mmc35240_resume)
 556 };
 557 
 558 static const struct of_device_id mmc35240_of_match[] = {
 559         { .compatible = "memsic,mmc35240", },
 560         { }
 561 };
 562 MODULE_DEVICE_TABLE(of, mmc35240_of_match);
 563 
 564 static const struct acpi_device_id mmc35240_acpi_match[] = {
 565         {"MMC35240", 0},
 566         { },
 567 };
 568 MODULE_DEVICE_TABLE(acpi, mmc35240_acpi_match);
 569 
 570 static const struct i2c_device_id mmc35240_id[] = {
 571         {"mmc35240", 0},
 572         {}
 573 };
 574 MODULE_DEVICE_TABLE(i2c, mmc35240_id);
 575 
 576 static struct i2c_driver mmc35240_driver = {
 577         .driver = {
 578                 .name = MMC35240_DRV_NAME,
 579                 .of_match_table = mmc35240_of_match,
 580                 .pm = &mmc35240_pm_ops,
 581                 .acpi_match_table = ACPI_PTR(mmc35240_acpi_match),
 582         },
 583         .probe          = mmc35240_probe,
 584         .id_table       = mmc35240_id,
 585 };
 586 
 587 module_i2c_driver(mmc35240_driver);
 588 
 589 MODULE_AUTHOR("Daniel Baluta <daniel.baluta@intel.com>");
 590 MODULE_DESCRIPTION("MEMSIC MMC35240 magnetic sensor driver");
 591 MODULE_LICENSE("GPL v2");
/* [<][>][^][v][top][bottom][index][help] */
root/drivers/iio/magnetometer/mmc35240.c

DEFINITIONS
