drivers/iio/pressure/bmp280.c

   1 /*
   2  * Copyright (c) 2014 Intel Corporation
   3  *
   4  * Driver for Bosch Sensortec 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  */
  11
  12 #define pr_fmt(fmt) "bmp280: " fmt
  13
  14 #include <linux/module.h>
  15 #include <linux/i2c.h>
  16 #include <linux/acpi.h>
  17 #include <linux/regmap.h>
  18 #include <linux/iio/iio.h>
  19 #include <linux/iio/sysfs.h>
  20
  21 #define BMP280_REG_TEMP_XLSB            0xFC
  22 #define BMP280_REG_TEMP_LSB             0xFB
  23 #define BMP280_REG_TEMP_MSB             0xFA
  24 #define BMP280_REG_PRESS_XLSB           0xF9
  25 #define BMP280_REG_PRESS_LSB            0xF8
  26 #define BMP280_REG_PRESS_MSB            0xF7
  27
  28 #define BMP280_REG_CONFIG               0xF5
  29 #define BMP280_REG_CTRL_MEAS            0xF4
  30 #define BMP280_REG_STATUS               0xF3
  31 #define BMP280_REG_RESET                0xE0
  32 #define BMP280_REG_ID                   0xD0
  33
  34 #define BMP280_REG_COMP_TEMP_START      0x88
  35 #define BMP280_COMP_TEMP_REG_COUNT      6
  36
  37 #define BMP280_REG_COMP_PRESS_START     0x8E
  38 #define BMP280_COMP_PRESS_REG_COUNT     18
  39
  40 #define BMP280_FILTER_MASK              (BIT(4) | BIT(3) | BIT(2))
  41 #define BMP280_FILTER_OFF               0
  42 #define BMP280_FILTER_2X                BIT(2)
  43 #define BMP280_FILTER_4X                BIT(3)
  44 #define BMP280_FILTER_8X                (BIT(3) | BIT(2))
  45 #define BMP280_FILTER_16X               BIT(4)
  46
  47 #define BMP280_OSRS_TEMP_MASK           (BIT(7) | BIT(6) | BIT(5))
  48 #define BMP280_OSRS_TEMP_SKIP           0
  49 #define BMP280_OSRS_TEMP_1X             BIT(5)
  50 #define BMP280_OSRS_TEMP_2X             BIT(6)
  51 #define BMP280_OSRS_TEMP_4X             (BIT(6) | BIT(5))
  52 #define BMP280_OSRS_TEMP_8X             BIT(7)
  53 #define BMP280_OSRS_TEMP_16X            (BIT(7) | BIT(5))
  54
  55 #define BMP280_OSRS_PRESS_MASK          (BIT(4) | BIT(3) | BIT(2))
  56 #define BMP280_OSRS_PRESS_SKIP          0
  57 #define BMP280_OSRS_PRESS_1X            BIT(2)
  58 #define BMP280_OSRS_PRESS_2X            BIT(3)
  59 #define BMP280_OSRS_PRESS_4X            (BIT(3) | BIT(2))
  60 #define BMP280_OSRS_PRESS_8X            BIT(4)
  61 #define BMP280_OSRS_PRESS_16X           (BIT(4) | BIT(2))
  62
  63 #define BMP280_MODE_MASK                (BIT(1) | BIT(0))
  64 #define BMP280_MODE_SLEEP               0
  65 #define BMP280_MODE_FORCED              BIT(0)
  66 #define BMP280_MODE_NORMAL              (BIT(1) | BIT(0))
  67
  68 #define BMP280_CHIP_ID                  0x58
  69 #define BMP280_SOFT_RESET_VAL           0xB6
  70
  71 struct bmp280_data {
  72         struct i2c_client *client;
  73         struct mutex lock;
  74         struct regmap *regmap;
  75
  76         /*
  77          * Carryover value from temperature conversion, used in pressure
  78          * calculation.
  79          */
  80         s32 t_fine;
  81 };
  82
  83 /*
  84  * These enums are used for indexing into the array of compensation
  85  * parameters.
  86  */
  87 enum { T1, T2, T3 };
  88 enum { P1, P2, P3, P4, P5, P6, P7, P8, P9 };
  89
  90 static const struct iio_chan_spec bmp280_channels[] = {
  91         {
  92                 .type = IIO_PRESSURE,
  93                 .info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
  94         },
  95         {
  96                 .type = IIO_TEMP,
  97                 .info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
  98         },
  99 };
 100
 101 static bool bmp280_is_writeable_reg(struct device *dev, unsigned int reg)
 102 {
 103         switch (reg) {
 104         case BMP280_REG_CONFIG:
 105         case BMP280_REG_CTRL_MEAS:
 106         case BMP280_REG_RESET:
 107                 return true;
 108         default:
 109                 return false;
 110         };
 111 }
 112
 113 static bool bmp280_is_volatile_reg(struct device *dev, unsigned int reg)
 114 {
 115         switch (reg) {
 116         case BMP280_REG_TEMP_XLSB:
 117         case BMP280_REG_TEMP_LSB:
 118         case BMP280_REG_TEMP_MSB:
 119         case BMP280_REG_PRESS_XLSB:
 120         case BMP280_REG_PRESS_LSB:
 121         case BMP280_REG_PRESS_MSB:
 122         case BMP280_REG_STATUS:
 123                 return true;
 124         default:
 125                 return false;
 126         }
 127 }
 128
 129 static const struct regmap_config bmp280_regmap_config = {
 130         .reg_bits = 8,
 131         .val_bits = 8,
 132
 133         .max_register = BMP280_REG_TEMP_XLSB,
 134         .cache_type = REGCACHE_RBTREE,
 135
 136         .writeable_reg = bmp280_is_writeable_reg,
 137         .volatile_reg = bmp280_is_volatile_reg,
 138 };
 139
 140 /*
 141  * Returns temperature in DegC, resolution is 0.01 DegC.  Output value of
 142  * "5123" equals 51.23 DegC.  t_fine carries fine temperature as global
 143  * value.
 144  *
 145  * Taken from datasheet, Section 3.11.3, "Compensation formula".
 146  */
 147 static s32 bmp280_compensate_temp(struct bmp280_data *data,
 148                                   s32 adc_temp)
 149 {
 150         int ret;
 151         s32 var1, var2;
 152         __le16 buf[BMP280_COMP_TEMP_REG_COUNT / 2];
 153
 154         ret = regmap_bulk_read(data->regmap, BMP280_REG_COMP_TEMP_START,
 155                                buf, BMP280_COMP_TEMP_REG_COUNT);
 156         if (ret < 0) {
 157                 dev_err(&data->client->dev,
 158                         "failed to read temperature calibration parameters\n");
 159                 return ret;
 160         }
 161
 162         /*
 163          * The double casts are necessary because le16_to_cpu returns an
 164          * unsigned 16-bit value.  Casting that value directly to a
 165          * signed 32-bit will not do proper sign extension.
 166          *
 167          * Conversely, T1 and P1 are unsigned values, so they can be
 168          * cast straight to the larger type.
 169          */
 170         var1 = (((adc_temp >> 3) - ((s32)le16_to_cpu(buf[T1]) << 1)) *
 171                 ((s32)(s16)le16_to_cpu(buf[T2]))) >> 11;
 172         var2 = (((((adc_temp >> 4) - ((s32)le16_to_cpu(buf[T1]))) *
 173                   ((adc_temp >> 4) - ((s32)le16_to_cpu(buf[T1])))) >> 12) *
 174                 ((s32)(s16)le16_to_cpu(buf[T3]))) >> 14;
 175
 176         return (data->t_fine * 5 + 128) >> 8;
 177 }
 178
 179 /*
 180  * Returns pressure in Pa as unsigned 32 bit integer in Q24.8 format (24
 181  * integer bits and 8 fractional bits).  Output value of "24674867"
 182  * represents 24674867/256 = 96386.2 Pa = 963.862 hPa
 183  *
 184  * Taken from datasheet, Section 3.11.3, "Compensation formula".
 185  */
 186 static u32 bmp280_compensate_press(struct bmp280_data *data,
 187                                    s32 adc_press)
 188 {
 189         int ret;
 190         s64 var1, var2, p;
 191         __le16 buf[BMP280_COMP_PRESS_REG_COUNT / 2];
 192
 193         ret = regmap_bulk_read(data->regmap, BMP280_REG_COMP_PRESS_START,
 194                                buf, BMP280_COMP_PRESS_REG_COUNT);
 195         if (ret < 0) {
 196                 dev_err(&data->client->dev,
 197                         "failed to read pressure calibration parameters\n");
 198                 return ret;
 199         }
 200
 201         var1 = ((s64)data->t_fine) - 128000;
 202         var2 = var1 * var1 * (s64)(s16)le16_to_cpu(buf[P6]);
 203         var2 += (var1 * (s64)(s16)le16_to_cpu(buf[P5])) << 17;
 204         var2 += ((s64)(s16)le16_to_cpu(buf[P4])) << 35;
 205         var1 = ((var1 * var1 * (s64)(s16)le16_to_cpu(buf[P3])) >> 8) +
 206                 ((var1 * (s64)(s16)le16_to_cpu(buf[P2])) << 12);
 207         var1 = ((((s64)1) << 47) + var1) * ((s64)le16_to_cpu(buf[P1])) >> 33;
 208
 209         if (var1 == 0)
 210                 return 0;
 211
 212         p = ((((s64)1048576 - adc_press) << 31) - var2) * 3125;
 213         p = div64_s64(p, var1);
 214         var1 = (((s64)(s16)le16_to_cpu(buf[P9])) * (p >> 13) * (p >> 13)) >> 25;
 215         var2 = (((s64)(s16)le16_to_cpu(buf[P8])) * p) >> 19;
 216         p = ((p + var1 + var2) >> 8) + (((s64)(s16)le16_to_cpu(buf[P7])) << 4);
 217
 218         return (u32)p;
 219 }
 220
 221 static int bmp280_read_temp(struct bmp280_data *data,
 222                             int *val)
 223 {
 224         int ret;
 225         __be32 tmp = 0;
 226         s32 adc_temp, comp_temp;
 227
 228         ret = regmap_bulk_read(data->regmap, BMP280_REG_TEMP_MSB,
 229                                (u8 *) &tmp, 3);
 230         if (ret < 0) {
 231                 dev_err(&data->client->dev, "failed to read temperature\n");
 232                 return ret;
 233         }
 234
 235         adc_temp = be32_to_cpu(tmp) >> 12;
 236         comp_temp = bmp280_compensate_temp(data, adc_temp);
 237
 238         /*
 239          * val might be NULL if we're called by the read_press routine,
 240          * who only cares about the carry over t_fine value.
 241          */
 242         if (val) {
 243                 *val = comp_temp * 10;
 244                 return IIO_VAL_INT;
 245         }
 246
 247         return 0;
 248 }
 249
 250 static int bmp280_read_press(struct bmp280_data *data,
 251                              int *val, int *val2)
 252 {
 253         int ret;
 254         __be32 tmp = 0;
 255         s32 adc_press;
 256         u32 comp_press;
 257
 258         /* Read and compensate temperature so we get a reading of t_fine. */
 259         ret = bmp280_read_temp(data, NULL);
 260         if (ret < 0)
 261                 return ret;
 262
 263         ret = regmap_bulk_read(data->regmap, BMP280_REG_PRESS_MSB,
 264                                (u8 *) &tmp, 3);
 265         if (ret < 0) {
 266                 dev_err(&data->client->dev, "failed to read pressure\n");
 267                 return ret;
 268         }
 269
 270         adc_press = be32_to_cpu(tmp) >> 12;
 271         comp_press = bmp280_compensate_press(data, adc_press);
 272
 273         *val = comp_press;
 274         *val2 = 256000;
 275
 276         return IIO_VAL_FRACTIONAL;
 277 }
 278
 279 static int bmp280_read_raw(struct iio_dev *indio_dev,
 280                            struct iio_chan_spec const *chan,
 281                            int *val, int *val2, long mask)
 282 {
 283         int ret;
 284         struct bmp280_data *data = iio_priv(indio_dev);
 285
 286         mutex_lock(&data->lock);
 287
 288         switch (mask) {
 289         case IIO_CHAN_INFO_PROCESSED:
 290                 switch (chan->type) {
 291                 case IIO_PRESSURE:
 292                         ret = bmp280_read_press(data, val, val2);
 293                         break;
 294                 case IIO_TEMP:
 295                         ret = bmp280_read_temp(data, val);
 296                         break;
 297                 default:
 298                         ret = -EINVAL;
 299                         break;
 300                 }
 301                 break;
 302         default:
 303                 ret = -EINVAL;
 304                 break;
 305         }
 306
 307         mutex_unlock(&data->lock);
 308
 309         return ret;
 310 }
 311
 312 static const struct iio_info bmp280_info = {
 313         .driver_module = THIS_MODULE,
 314         .read_raw = &bmp280_read_raw,
 315 };
 316
 317 static int bmp280_chip_init(struct bmp280_data *data)
 318 {
 319         int ret;
 320
 321         ret = regmap_update_bits(data->regmap, BMP280_REG_CTRL_MEAS,
 322                                  BMP280_OSRS_TEMP_MASK |
 323                                  BMP280_OSRS_PRESS_MASK |
 324                                  BMP280_MODE_MASK,
 325                                  BMP280_OSRS_TEMP_2X |
 326                                  BMP280_OSRS_PRESS_16X |
 327                                  BMP280_MODE_NORMAL);
 328         if (ret < 0) {
 329                 dev_err(&data->client->dev,
 330                         "failed to write ctrl_meas register\n");
 331                 return ret;
 332         }
 333
 334         ret = regmap_update_bits(data->regmap, BMP280_REG_CONFIG,
 335                                  BMP280_FILTER_MASK,
 336                                  BMP280_FILTER_4X);
 337         if (ret < 0) {
 338                 dev_err(&data->client->dev,
 339                         "failed to write config register\n");
 340                 return ret;
 341         }
 342
 343         return ret;
 344 }
 345
 346 static int bmp280_probe(struct i2c_client *client,
 347                         const struct i2c_device_id *id)
 348 {
 349         int ret;
 350         struct iio_dev *indio_dev;
 351         struct bmp280_data *data;
 352         unsigned int chip_id;
 353
 354         indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
 355         if (!indio_dev)
 356                 return -ENOMEM;
 357
 358         data = iio_priv(indio_dev);
 359         mutex_init(&data->lock);
 360         data->client = client;
 361
 362         indio_dev->dev.parent = &client->dev;
 363         indio_dev->name = id->name;
 364         indio_dev->channels = bmp280_channels;
 365         indio_dev->num_channels = ARRAY_SIZE(bmp280_channels);
 366         indio_dev->info = &bmp280_info;
 367         indio_dev->modes = INDIO_DIRECT_MODE;
 368
 369         data->regmap = devm_regmap_init_i2c(client, &bmp280_regmap_config);
 370         if (IS_ERR(data->regmap)) {
 371                 dev_err(&client->dev, "failed to allocate register map\n");
 372                 return PTR_ERR(data->regmap);
 373         }
 374
 375         ret = regmap_read(data->regmap, BMP280_REG_ID, &chip_id);
 376         if (ret < 0)
 377                 return ret;
 378         if (chip_id != BMP280_CHIP_ID) {
 379                 dev_err(&client->dev, "bad chip id.  expected %x got %x\n",
 380                         BMP280_CHIP_ID, chip_id);
 381                 return -EINVAL;
 382         }
 383
 384         ret = bmp280_chip_init(data);
 385         if (ret < 0)
 386                 return ret;
 387
 388         return devm_iio_device_register(&client->dev, indio_dev);
 389 }
 390
 391 static const struct acpi_device_id bmp280_acpi_match[] = {
 392         {"BMP0280", 0},
 393         { },
 394 };
 395 MODULE_DEVICE_TABLE(acpi, bmp280_acpi_match);
 396
 397 static const struct i2c_device_id bmp280_id[] = {
 398         {"bmp280", 0},
 399         { },
 400 };
 401 MODULE_DEVICE_TABLE(i2c, bmp280_id);
 402
 403 static struct i2c_driver bmp280_driver = {
 404         .driver = {
 405                 .name   = "bmp280",
 406                 .acpi_match_table = ACPI_PTR(bmp280_acpi_match),
 407         },
 408         .probe          = bmp280_probe,
 409         .id_table       = bmp280_id,
 410 };
 411 module_i2c_driver(bmp280_driver);
 412
 413 MODULE_AUTHOR("Vlad Dogaru <vlad.dogaru@intel.com>");
 414 MODULE_DESCRIPTION("Driver for Bosch Sensortec BMP280 pressure and temperature sensor");
 415 MODULE_LICENSE("GPL v2");