drivers/iio/pressure/bmp280.c

   1 /*
   2  * Copyright (c) 2014 Intel Corporation
   3  *
   4  * Driver for Bosch Sensortec BMP180 and BMP280 digital pressure sensor.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  *
  10  * Datasheet:
  11  * https://ae-bst.resource.bosch.com/media/_tech/media/datasheets/BST-BMP180-DS000-121.pdf
  12  * https://ae-bst.resource.bosch.com/media/_tech/media/datasheets/BST-BMP280-DS001-12.pdf
  13  */
  14
  15 #define pr_fmt(fmt) "bmp280: " fmt
  16
  17 #include <linux/module.h>
  18 #include <linux/i2c.h>
  19 #include <linux/acpi.h>
  20 #include <linux/regmap.h>
  21 #include <linux/delay.h>
  22 #include <linux/iio/iio.h>
  23 #include <linux/iio/sysfs.h>
  24
  25 /* BMP280 specific registers */
  26 #define BMP280_REG_TEMP_XLSB            0xFC
  27 #define BMP280_REG_TEMP_LSB             0xFB
  28 #define BMP280_REG_TEMP_MSB             0xFA
  29 #define BMP280_REG_PRESS_XLSB           0xF9
  30 #define BMP280_REG_PRESS_LSB            0xF8
  31 #define BMP280_REG_PRESS_MSB            0xF7
  32
  33 #define BMP280_REG_CONFIG               0xF5
  34 #define BMP280_REG_STATUS               0xF3
  35
  36 #define BMP280_REG_COMP_TEMP_START      0x88
  37 #define BMP280_COMP_TEMP_REG_COUNT      6
  38
  39 #define BMP280_REG_COMP_PRESS_START     0x8E
  40 #define BMP280_COMP_PRESS_REG_COUNT     18
  41
  42 #define BMP280_FILTER_MASK              (BIT(4) | BIT(3) | BIT(2))
  43 #define BMP280_FILTER_OFF               0
  44 #define BMP280_FILTER_2X                BIT(2)
  45 #define BMP280_FILTER_4X                BIT(3)
  46 #define BMP280_FILTER_8X                (BIT(3) | BIT(2))
  47 #define BMP280_FILTER_16X               BIT(4)
  48
  49 #define BMP280_OSRS_TEMP_MASK           (BIT(7) | BIT(6) | BIT(5))
  50 #define BMP280_OSRS_TEMP_SKIP           0
  51 #define BMP280_OSRS_TEMP_1X             BIT(5)
  52 #define BMP280_OSRS_TEMP_2X             BIT(6)
  53 #define BMP280_OSRS_TEMP_4X             (BIT(6) | BIT(5))
  54 #define BMP280_OSRS_TEMP_8X             BIT(7)
  55 #define BMP280_OSRS_TEMP_16X            (BIT(7) | BIT(5))
  56
  57 #define BMP280_OSRS_PRESS_MASK          (BIT(4) | BIT(3) | BIT(2))
  58 #define BMP280_OSRS_PRESS_SKIP          0
  59 #define BMP280_OSRS_PRESS_1X            BIT(2)
  60 #define BMP280_OSRS_PRESS_2X            BIT(3)
  61 #define BMP280_OSRS_PRESS_4X            (BIT(3) | BIT(2))
  62 #define BMP280_OSRS_PRESS_8X            BIT(4)
  63 #define BMP280_OSRS_PRESS_16X           (BIT(4) | BIT(2))
  64
  65 #define BMP280_MODE_MASK                (BIT(1) | BIT(0))
  66 #define BMP280_MODE_SLEEP               0
  67 #define BMP280_MODE_FORCED              BIT(0)
  68 #define BMP280_MODE_NORMAL              (BIT(1) | BIT(0))
  69
  70 /* BMP180 specific registers */
  71 #define BMP180_REG_OUT_XLSB             0xF8
  72 #define BMP180_REG_OUT_LSB              0xF7
  73 #define BMP180_REG_OUT_MSB              0xF6
  74
  75 #define BMP180_REG_CALIB_START          0xAA
  76 #define BMP180_REG_CALIB_COUNT          22
  77
  78 #define BMP180_MEAS_SCO                 BIT(5)
  79 #define BMP180_MEAS_TEMP                (0x0E | BMP180_MEAS_SCO)
  80 #define BMP180_MEAS_PRESS_X(oss)        ((oss) << 6 | 0x14 | BMP180_MEAS_SCO)
  81 #define BMP180_MEAS_PRESS_1X            BMP180_MEAS_PRESS_X(0)
  82 #define BMP180_MEAS_PRESS_2X            BMP180_MEAS_PRESS_X(1)
  83 #define BMP180_MEAS_PRESS_4X            BMP180_MEAS_PRESS_X(2)
  84 #define BMP180_MEAS_PRESS_8X            BMP180_MEAS_PRESS_X(3)
  85
  86 /* BMP180 and BMP280 common registers */
  87 #define BMP280_REG_CTRL_MEAS            0xF4
  88 #define BMP280_REG_RESET                0xE0
  89 #define BMP280_REG_ID                   0xD0
  90
  91 #define BMP180_CHIP_ID                  0x55
  92 #define BMP280_CHIP_ID                  0x58
  93 #define BMP280_SOFT_RESET_VAL           0xB6
  94
  95 struct bmp280_data {
  96         struct i2c_client *client;
  97         struct mutex lock;
  98         struct regmap *regmap;
  99         const struct bmp280_chip_info *chip_info;
 100
 101         /*
 102          * Carryover value from temperature conversion, used in pressure
 103          * calculation.
 104          */
 105         s32 t_fine;
 106 };
 107
 108 struct bmp280_chip_info {
 109         const struct regmap_config *regmap_config;
 110
 111         int (*chip_config)(struct bmp280_data *);
 112         int (*read_temp)(struct bmp280_data *, int *);
 113         int (*read_press)(struct bmp280_data *, int *, int *);
 114 };
 115
 116 /*
 117  * These enums are used for indexing into the array of compensation
 118  * parameters for BMP280.
 119  */
 120 enum { T1, T2, T3 };
 121 enum { P1, P2, P3, P4, P5, P6, P7, P8, P9 };
 122
 123 static const struct iio_chan_spec bmp280_channels[] = {
 124         {
 125                 .type = IIO_PRESSURE,
 126                 .info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
 127         },
 128         {
 129                 .type = IIO_TEMP,
 130                 .info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
 131         },
 132 };
 133
 134 static bool bmp280_is_writeable_reg(struct device *dev, unsigned int reg)
 135 {
 136         switch (reg) {
 137         case BMP280_REG_CONFIG:
 138         case BMP280_REG_CTRL_MEAS:
 139         case BMP280_REG_RESET:
 140                 return true;
 141         default:
 142                 return false;
 143         };
 144 }
 145
 146 static bool bmp280_is_volatile_reg(struct device *dev, unsigned int reg)
 147 {
 148         switch (reg) {
 149         case BMP280_REG_TEMP_XLSB:
 150         case BMP280_REG_TEMP_LSB:
 151         case BMP280_REG_TEMP_MSB:
 152         case BMP280_REG_PRESS_XLSB:
 153         case BMP280_REG_PRESS_LSB:
 154         case BMP280_REG_PRESS_MSB:
 155         case BMP280_REG_STATUS:
 156                 return true;
 157         default:
 158                 return false;
 159         }
 160 }
 161
 162 static const struct regmap_config bmp280_regmap_config = {
 163         .reg_bits = 8,
 164         .val_bits = 8,
 165
 166         .max_register = BMP280_REG_TEMP_XLSB,
 167         .cache_type = REGCACHE_RBTREE,
 168
 169         .writeable_reg = bmp280_is_writeable_reg,
 170         .volatile_reg = bmp280_is_volatile_reg,
 171 };
 172
 173 /*
 174  * Returns temperature in DegC, resolution is 0.01 DegC.  Output value of
 175  * "5123" equals 51.23 DegC.  t_fine carries fine temperature as global
 176  * value.
 177  *
 178  * Taken from datasheet, Section 3.11.3, "Compensation formula".
 179  */
 180 static s32 bmp280_compensate_temp(struct bmp280_data *data,
 181                                   s32 adc_temp)
 182 {
 183         int ret;
 184         s32 var1, var2;
 185         __le16 buf[BMP280_COMP_TEMP_REG_COUNT / 2];
 186
 187         ret = regmap_bulk_read(data->regmap, BMP280_REG_COMP_TEMP_START,
 188                                buf, BMP280_COMP_TEMP_REG_COUNT);
 189         if (ret < 0) {
 190                 dev_err(&data->client->dev,
 191                         "failed to read temperature calibration parameters\n");
 192                 return ret;
 193         }
 194
 195         /*
 196          * The double casts are necessary because le16_to_cpu returns an
 197          * unsigned 16-bit value.  Casting that value directly to a
 198          * signed 32-bit will not do proper sign extension.
 199          *
 200          * Conversely, T1 and P1 are unsigned values, so they can be
 201          * cast straight to the larger type.
 202          */
 203         var1 = (((adc_temp >> 3) - ((s32)le16_to_cpu(buf[T1]) << 1)) *
 204                 ((s32)(s16)le16_to_cpu(buf[T2]))) >> 11;
 205         var2 = (((((adc_temp >> 4) - ((s32)le16_to_cpu(buf[T1]))) *
 206                   ((adc_temp >> 4) - ((s32)le16_to_cpu(buf[T1])))) >> 12) *
 207                 ((s32)(s16)le16_to_cpu(buf[T3]))) >> 14;
 208         data->t_fine = var1 + var2;
 209
 210         return (data->t_fine * 5 + 128) >> 8;
 211 }
 212
 213 /*
 214  * Returns pressure in Pa as unsigned 32 bit integer in Q24.8 format (24
 215  * integer bits and 8 fractional bits).  Output value of "24674867"
 216  * represents 24674867/256 = 96386.2 Pa = 963.862 hPa
 217  *
 218  * Taken from datasheet, Section 3.11.3, "Compensation formula".
 219  */
 220 static u32 bmp280_compensate_press(struct bmp280_data *data,
 221                                    s32 adc_press)
 222 {
 223         int ret;
 224         s64 var1, var2, p;
 225         __le16 buf[BMP280_COMP_PRESS_REG_COUNT / 2];
 226
 227         ret = regmap_bulk_read(data->regmap, BMP280_REG_COMP_PRESS_START,
 228                                buf, BMP280_COMP_PRESS_REG_COUNT);
 229         if (ret < 0) {
 230                 dev_err(&data->client->dev,
 231                         "failed to read pressure calibration parameters\n");
 232                 return ret;
 233         }
 234
 235         var1 = ((s64)data->t_fine) - 128000;
 236         var2 = var1 * var1 * (s64)(s16)le16_to_cpu(buf[P6]);
 237         var2 += (var1 * (s64)(s16)le16_to_cpu(buf[P5])) << 17;
 238         var2 += ((s64)(s16)le16_to_cpu(buf[P4])) << 35;
 239         var1 = ((var1 * var1 * (s64)(s16)le16_to_cpu(buf[P3])) >> 8) +
 240                 ((var1 * (s64)(s16)le16_to_cpu(buf[P2])) << 12);
 241         var1 = ((((s64)1) << 47) + var1) * ((s64)le16_to_cpu(buf[P1])) >> 33;
 242
 243         if (var1 == 0)
 244                 return 0;
 245
 246         p = ((((s64)1048576 - adc_press) << 31) - var2) * 3125;
 247         p = div64_s64(p, var1);
 248         var1 = (((s64)(s16)le16_to_cpu(buf[P9])) * (p >> 13) * (p >> 13)) >> 25;
 249         var2 = (((s64)(s16)le16_to_cpu(buf[P8])) * p) >> 19;
 250         p = ((p + var1 + var2) >> 8) + (((s64)(s16)le16_to_cpu(buf[P7])) << 4);
 251
 252         return (u32)p;
 253 }
 254
 255 static int bmp280_read_temp(struct bmp280_data *data,
 256                             int *val)
 257 {
 258         int ret;
 259         __be32 tmp = 0;
 260         s32 adc_temp, comp_temp;
 261
 262         ret = regmap_bulk_read(data->regmap, BMP280_REG_TEMP_MSB,
 263                                (u8 *) &tmp, 3);
 264         if (ret < 0) {
 265                 dev_err(&data->client->dev, "failed to read temperature\n");
 266                 return ret;
 267         }
 268
 269         adc_temp = be32_to_cpu(tmp) >> 12;
 270         comp_temp = bmp280_compensate_temp(data, adc_temp);
 271
 272         /*
 273          * val might be NULL if we're called by the read_press routine,
 274          * who only cares about the carry over t_fine value.
 275          */
 276         if (val) {
 277                 *val = comp_temp * 10;
 278                 return IIO_VAL_INT;
 279         }
 280
 281         return 0;
 282 }
 283
 284 static int bmp280_read_press(struct bmp280_data *data,
 285                              int *val, int *val2)
 286 {
 287         int ret;
 288         __be32 tmp = 0;
 289         s32 adc_press;
 290         u32 comp_press;
 291
 292         /* Read and compensate temperature so we get a reading of t_fine. */
 293         ret = bmp280_read_temp(data, NULL);
 294         if (ret < 0)
 295                 return ret;
 296
 297         ret = regmap_bulk_read(data->regmap, BMP280_REG_PRESS_MSB,
 298                                (u8 *) &tmp, 3);
 299         if (ret < 0) {
 300                 dev_err(&data->client->dev, "failed to read pressure\n");
 301                 return ret;
 302         }
 303
 304         adc_press = be32_to_cpu(tmp) >> 12;
 305         comp_press = bmp280_compensate_press(data, adc_press);
 306
 307         *val = comp_press;
 308         *val2 = 256000;
 309
 310         return IIO_VAL_FRACTIONAL;
 311 }
 312
 313 static int bmp280_read_raw(struct iio_dev *indio_dev,
 314                            struct iio_chan_spec const *chan,
 315                            int *val, int *val2, long mask)
 316 {
 317         int ret;
 318         struct bmp280_data *data = iio_priv(indio_dev);
 319
 320         mutex_lock(&data->lock);
 321
 322         switch (mask) {
 323         case IIO_CHAN_INFO_PROCESSED:
 324                 switch (chan->type) {
 325                 case IIO_PRESSURE:
 326                         ret = data->chip_info->read_press(data, val, val2);
 327                         break;
 328                 case IIO_TEMP:
 329                         ret = data->chip_info->read_temp(data, val);
 330                         break;
 331                 default:
 332                         ret = -EINVAL;
 333                         break;
 334                 }
 335                 break;
 336         default:
 337                 ret = -EINVAL;
 338                 break;
 339         }
 340
 341         mutex_unlock(&data->lock);
 342
 343         return ret;
 344 }
 345
 346 static const struct iio_info bmp280_info = {
 347         .driver_module = THIS_MODULE,
 348         .read_raw = &bmp280_read_raw,
 349 };
 350
 351 static int bmp280_chip_config(struct bmp280_data *data)
 352 {
 353         int ret;
 354
 355         ret = regmap_update_bits(data->regmap, BMP280_REG_CTRL_MEAS,
 356                                  BMP280_OSRS_TEMP_MASK |
 357                                  BMP280_OSRS_PRESS_MASK |
 358                                  BMP280_MODE_MASK,
 359                                  BMP280_OSRS_TEMP_2X |
 360                                  BMP280_OSRS_PRESS_16X |
 361                                  BMP280_MODE_NORMAL);
 362         if (ret < 0) {
 363                 dev_err(&data->client->dev,
 364                         "failed to write ctrl_meas register\n");
 365                 return ret;
 366         }
 367
 368         ret = regmap_update_bits(data->regmap, BMP280_REG_CONFIG,
 369                                  BMP280_FILTER_MASK,
 370                                  BMP280_FILTER_4X);
 371         if (ret < 0) {
 372                 dev_err(&data->client->dev,
 373                         "failed to write config register\n");
 374                 return ret;
 375         }
 376
 377         return ret;
 378 }
 379
 380 static const struct bmp280_chip_info bmp280_chip_info = {
 381         .regmap_config = &bmp280_regmap_config,
 382         .chip_config = bmp280_chip_config,
 383         .read_temp = bmp280_read_temp,
 384         .read_press = bmp280_read_press,
 385 };
 386
 387 static bool bmp180_is_writeable_reg(struct device *dev, unsigned int reg)
 388 {
 389         switch (reg) {
 390         case BMP280_REG_CTRL_MEAS:
 391         case BMP280_REG_RESET:
 392                 return true;
 393         default:
 394                 return false;
 395         };
 396 }
 397
 398 static bool bmp180_is_volatile_reg(struct device *dev, unsigned int reg)
 399 {
 400         switch (reg) {
 401         case BMP180_REG_OUT_XLSB:
 402         case BMP180_REG_OUT_LSB:
 403         case BMP180_REG_OUT_MSB:
 404         case BMP280_REG_CTRL_MEAS:
 405                 return true;
 406         default:
 407                 return false;
 408         }
 409 }
 410
 411 static const struct regmap_config bmp180_regmap_config = {
 412         .reg_bits = 8,
 413         .val_bits = 8,
 414
 415         .max_register = BMP180_REG_OUT_XLSB,
 416         .cache_type = REGCACHE_RBTREE,
 417
 418         .writeable_reg = bmp180_is_writeable_reg,
 419         .volatile_reg = bmp180_is_volatile_reg,
 420 };
 421
 422 static int bmp180_measure(struct bmp280_data *data, u8 ctrl_meas)
 423 {
 424         int ret;
 425         const int conversion_time_max[] = { 4500, 7500, 13500, 25500 };
 426         unsigned int delay_us;
 427         unsigned int ctrl;
 428
 429         ret = regmap_write(data->regmap, BMP280_REG_CTRL_MEAS, ctrl_meas);
 430         if (ret)
 431                 return ret;
 432
 433         if (ctrl_meas == BMP180_MEAS_TEMP)
 434                 delay_us = 4500;
 435         else
 436                 delay_us = conversion_time_max[ilog2(8)];
 437
 438         usleep_range(delay_us, delay_us + 1000);
 439
 440         ret = regmap_read(data->regmap, BMP280_REG_CTRL_MEAS, &ctrl);
 441         if (ret)
 442                 return ret;
 443
 444         /* The value of this bit reset to "0" after conversion is complete */
 445         if (ctrl & BMP180_MEAS_SCO)
 446                 return -EIO;
 447
 448         return 0;
 449 }
 450
 451 static int bmp180_read_adc_temp(struct bmp280_data *data, int *val)
 452 {
 453         int ret;
 454         __be16 tmp = 0;
 455
 456         ret = bmp180_measure(data, BMP180_MEAS_TEMP);
 457         if (ret)
 458                 return ret;
 459
 460         ret = regmap_bulk_read(data->regmap, BMP180_REG_OUT_MSB, (u8 *)&tmp, 2);
 461         if (ret)
 462                 return ret;
 463
 464         *val = be16_to_cpu(tmp);
 465
 466         return 0;
 467 }
 468
 469 /*
 470  * These enums are used for indexing into the array of calibration
 471  * coefficients for BMP180.
 472  */
 473 enum { AC1, AC2, AC3, AC4, AC5, AC6, B1, B2, MB, MC, MD };
 474
 475 struct bmp180_calib {
 476         s16 AC1;
 477         s16 AC2;
 478         s16 AC3;
 479         u16 AC4;
 480         u16 AC5;
 481         u16 AC6;
 482         s16 B1;
 483         s16 B2;
 484         s16 MB;
 485         s16 MC;
 486         s16 MD;
 487 };
 488
 489 static int bmp180_read_calib(struct bmp280_data *data,
 490                              struct bmp180_calib *calib)
 491 {
 492         int ret;
 493         int i;
 494         __be16 buf[BMP180_REG_CALIB_COUNT / 2];
 495
 496         ret = regmap_bulk_read(data->regmap, BMP180_REG_CALIB_START, buf,
 497                                sizeof(buf));
 498
 499         if (ret < 0)
 500                 return ret;
 501
 502         /* None of the words has the value 0 or 0xFFFF */
 503         for (i = 0; i < ARRAY_SIZE(buf); i++) {
 504                 if (buf[i] == cpu_to_be16(0) || buf[i] == cpu_to_be16(0xffff))
 505                         return -EIO;
 506         }
 507
 508         calib->AC1 = be16_to_cpu(buf[AC1]);
 509         calib->AC2 = be16_to_cpu(buf[AC2]);
 510         calib->AC3 = be16_to_cpu(buf[AC3]);
 511         calib->AC4 = be16_to_cpu(buf[AC4]);
 512         calib->AC5 = be16_to_cpu(buf[AC5]);
 513         calib->AC6 = be16_to_cpu(buf[AC6]);
 514         calib->B1 = be16_to_cpu(buf[B1]);
 515         calib->B2 = be16_to_cpu(buf[B2]);
 516         calib->MB = be16_to_cpu(buf[MB]);
 517         calib->MC = be16_to_cpu(buf[MC]);
 518         calib->MD = be16_to_cpu(buf[MD]);
 519
 520         return 0;
 521 }
 522
 523 /*
 524  * Returns temperature in DegC, resolution is 0.1 DegC.
 525  * t_fine carries fine temperature as global value.
 526  *
 527  * Taken from datasheet, Section 3.5, "Calculating pressure and temperature".
 528  */
 529 static s32 bmp180_compensate_temp(struct bmp280_data *data, s32 adc_temp)
 530 {
 531         int ret;
 532         s32 x1, x2;
 533         struct bmp180_calib calib;
 534
 535         ret = bmp180_read_calib(data, &calib);
 536         if (ret < 0) {
 537                 dev_err(&data->client->dev,
 538                         "failed to read calibration coefficients\n");
 539                 return ret;
 540         }
 541
 542         x1 = ((adc_temp - calib.AC6) * calib.AC5) >> 15;
 543         x2 = (calib.MC << 11) / (x1 + calib.MD);
 544         data->t_fine = x1 + x2;
 545
 546         return (data->t_fine + 8) >> 4;
 547 }
 548
 549 static int bmp180_read_temp(struct bmp280_data *data, int *val)
 550 {
 551         int ret;
 552         s32 adc_temp, comp_temp;
 553
 554         ret = bmp180_read_adc_temp(data, &adc_temp);
 555         if (ret)
 556                 return ret;
 557
 558         comp_temp = bmp180_compensate_temp(data, adc_temp);
 559
 560         /*
 561          * val might be NULL if we're called by the read_press routine,
 562          * who only cares about the carry over t_fine value.
 563          */
 564         if (val) {
 565                 *val = comp_temp * 100;
 566                 return IIO_VAL_INT;
 567         }
 568
 569         return 0;
 570 }
 571
 572 static int bmp180_read_adc_press(struct bmp280_data *data, int *val)
 573 {
 574         int ret;
 575         __be32 tmp = 0;
 576         u8 oss = ilog2(8);
 577
 578         ret = bmp180_measure(data, BMP180_MEAS_PRESS_X(oss));
 579         if (ret)
 580                 return ret;
 581
 582         ret = regmap_bulk_read(data->regmap, BMP180_REG_OUT_MSB, (u8 *)&tmp, 3);
 583         if (ret)
 584                 return ret;
 585
 586         *val = (be32_to_cpu(tmp) >> 8) >> (8 - oss);
 587
 588         return 0;
 589 }
 590
 591 /*
 592  * Returns pressure in Pa, resolution is 1 Pa.
 593  *
 594  * Taken from datasheet, Section 3.5, "Calculating pressure and temperature".
 595  */
 596 static u32 bmp180_compensate_press(struct bmp280_data *data, s32 adc_press)
 597 {
 598         int ret;
 599         s32 x1, x2, x3, p;
 600         s32 b3, b6;
 601         u32 b4, b7;
 602         s32 oss = ilog2(8);
 603         struct bmp180_calib calib;
 604
 605         ret = bmp180_read_calib(data, &calib);
 606         if (ret < 0) {
 607                 dev_err(&data->client->dev,
 608                         "failed to read calibration coefficients\n");
 609                 return ret;
 610         }
 611
 612         b6 = data->t_fine - 4000;
 613         x1 = (calib.B2 * (b6 * b6 >> 12)) >> 11;
 614         x2 = calib.AC2 * b6 >> 11;
 615         x3 = x1 + x2;
 616         b3 = ((((s32)calib.AC1 * 4 + x3) << oss) + 2) / 4;
 617         x1 = calib.AC3 * b6 >> 13;
 618         x2 = (calib.B1 * ((b6 * b6) >> 12)) >> 16;
 619         x3 = (x1 + x2 + 2) >> 2;
 620         b4 = calib.AC4 * (u32)(x3 + 32768) >> 15;
 621         b7 = ((u32)adc_press - b3) * (50000 >> oss);
 622         if (b7 < 0x80000000)
 623                 p = (b7 * 2) / b4;
 624         else
 625                 p = (b7 / b4) * 2;
 626
 627         x1 = (p >> 8) * (p >> 8);
 628         x1 = (x1 * 3038) >> 16;
 629         x2 = (-7357 * p) >> 16;
 630
 631         return p + ((x1 + x2 + 3791) >> 4);
 632 }
 633
 634 static int bmp180_read_press(struct bmp280_data *data,
 635                              int *val, int *val2)
 636 {
 637         int ret;
 638         s32 adc_press;
 639         u32 comp_press;
 640
 641         /* Read and compensate temperature so we get a reading of t_fine. */
 642         ret = bmp180_read_temp(data, NULL);
 643         if (ret)
 644                 return ret;
 645
 646         ret = bmp180_read_adc_press(data, &adc_press);
 647         if (ret)
 648                 return ret;
 649
 650         comp_press = bmp180_compensate_press(data, adc_press);
 651
 652         *val = comp_press;
 653         *val2 = 1000;
 654
 655         return IIO_VAL_FRACTIONAL;
 656 }
 657
 658 static int bmp180_chip_config(struct bmp280_data *data)
 659 {
 660         return 0;
 661 }
 662
 663 static const struct bmp280_chip_info bmp180_chip_info = {
 664         .regmap_config = &bmp180_regmap_config,
 665         .chip_config = bmp180_chip_config,
 666         .read_temp = bmp180_read_temp,
 667         .read_press = bmp180_read_press,
 668 };
 669
 670 static int bmp280_probe(struct i2c_client *client,
 671                         const struct i2c_device_id *id)
 672 {
 673         int ret;
 674         struct iio_dev *indio_dev;
 675         struct bmp280_data *data;
 676         unsigned int chip_id;
 677
 678         indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
 679         if (!indio_dev)
 680                 return -ENOMEM;
 681
 682         data = iio_priv(indio_dev);
 683         mutex_init(&data->lock);
 684         data->client = client;
 685
 686         indio_dev->dev.parent = &client->dev;
 687         indio_dev->name = id->name;
 688         indio_dev->channels = bmp280_channels;
 689         indio_dev->num_channels = ARRAY_SIZE(bmp280_channels);
 690         indio_dev->info = &bmp280_info;
 691         indio_dev->modes = INDIO_DIRECT_MODE;
 692
 693         switch (id->driver_data) {
 694         case BMP180_CHIP_ID:
 695                 data->chip_info = &bmp180_chip_info;
 696                 break;
 697         case BMP280_CHIP_ID:
 698                 data->chip_info = &bmp280_chip_info;
 699                 break;
 700         default:
 701                 return -EINVAL;
 702         }
 703
 704         data->regmap = devm_regmap_init_i2c(client,
 705                                         data->chip_info->regmap_config);
 706         if (IS_ERR(data->regmap)) {
 707                 dev_err(&client->dev, "failed to allocate register map\n");
 708                 return PTR_ERR(data->regmap);
 709         }
 710
 711         ret = regmap_read(data->regmap, BMP280_REG_ID, &chip_id);
 712         if (ret < 0)
 713                 return ret;
 714         if (chip_id != id->driver_data) {
 715                 dev_err(&client->dev, "bad chip id.  expected %x got %x\n",
 716                         BMP280_CHIP_ID, chip_id);
 717                 return -EINVAL;
 718         }
 719
 720         ret = data->chip_info->chip_config(data);
 721         if (ret < 0)
 722                 return ret;
 723
 724         return devm_iio_device_register(&client->dev, indio_dev);
 725 }
 726
 727 static const struct acpi_device_id bmp280_acpi_match[] = {
 728         {"BMP0280", BMP280_CHIP_ID },
 729         {"BMP0180", BMP180_CHIP_ID },
 730         {"BMP0085", BMP180_CHIP_ID },
 731         { },
 732 };
 733 MODULE_DEVICE_TABLE(acpi, bmp280_acpi_match);
 734
 735 static const struct i2c_device_id bmp280_id[] = {
 736         {"bmp280", BMP280_CHIP_ID },
 737         {"bmp180", BMP180_CHIP_ID },
 738         {"bmp085", BMP180_CHIP_ID },
 739         { },
 740 };
 741 MODULE_DEVICE_TABLE(i2c, bmp280_id);
 742
 743 static struct i2c_driver bmp280_driver = {
 744         .driver = {
 745                 .name   = "bmp280",
 746                 .acpi_match_table = ACPI_PTR(bmp280_acpi_match),
 747         },
 748         .probe          = bmp280_probe,
 749         .id_table       = bmp280_id,
 750 };
 751 module_i2c_driver(bmp280_driver);
 752
 753 MODULE_AUTHOR("Vlad Dogaru <vlad.dogaru@intel.com>");
 754 MODULE_DESCRIPTION("Driver for Bosch Sensortec BMP180/BMP280 pressure and temperature sensor");
 755 MODULE_LICENSE("GPL v2");