root/drivers/iio/common/ms_sensors/ms_sensors_i2c.c

DEFINITIONS

1. ms_sensors_reset
2. ms_sensors_read_prom_word
3. ms_sensors_convert_and_read
4. ms_sensors_crc_valid
5. ms_sensors_read_serial
6. ms_sensors_read_config_reg
7. ms_sensors_write_resolution
8. ms_sensors_show_battery_low
9. ms_sensors_show_heater
10. ms_sensors_write_heater
11. ms_sensors_ht_read_temperature
12. ms_sensors_ht_read_humidity
13. ms_sensors_tp_crc_valid
14. ms_sensors_tp_read_prom
15. ms_sensors_read_temp_and_pressure

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Measurements Specialties driver common i2c functions
   4  *
   5  * Copyright (c) 2015 Measurement-Specialties
   6  */
   7 
   8 #include <linux/module.h>
   9 #include <linux/iio/iio.h>
  10 #include <linux/device.h>
  11 #include <linux/delay.h>
  12 
  13 #include "ms_sensors_i2c.h"
  14 
  15 /* Conversion times in us */
  16 static const u16 ms_sensors_ht_t_conversion_time[] = { 50000, 25000,
  17                                                        13000, 7000 };
  18 static const u16 ms_sensors_ht_h_conversion_time[] = { 16000, 3000,
  19                                                        5000, 8000 };
  20 static const u16 ms_sensors_tp_conversion_time[] = { 500, 1100, 2100,
  21                                                      4100, 8220, 16440 };
  22 
  23 #define MS_SENSORS_SERIAL_READ_MSB              0xFA0F
  24 #define MS_SENSORS_SERIAL_READ_LSB              0xFCC9
  25 #define MS_SENSORS_CONFIG_REG_WRITE             0xE6
  26 #define MS_SENSORS_CONFIG_REG_READ              0xE7
  27 #define MS_SENSORS_HT_T_CONVERSION_START        0xF3
  28 #define MS_SENSORS_HT_H_CONVERSION_START        0xF5
  29 
  30 #define MS_SENSORS_TP_PROM_READ                 0xA0
  31 #define MS_SENSORS_TP_T_CONVERSION_START        0x50
  32 #define MS_SENSORS_TP_P_CONVERSION_START        0x40
  33 #define MS_SENSORS_TP_ADC_READ                  0x00
  34 
  35 #define MS_SENSORS_NO_READ_CMD                  0xFF
  36 
  37 /**
  38  * ms_sensors_reset() - Reset function
  39  * @cli:        pointer to device client
  40  * @cmd:        reset cmd. Depends on device in use
  41  * @delay:      usleep minimal delay after reset command is issued
  42  *
  43  * Generic I2C reset function for Measurement Specialties devices.
  44  *
  45  * Return: 0 on success, negative errno otherwise.
  46  */
  47 int ms_sensors_reset(void *cli, u8 cmd, unsigned int delay)
  48 {
  49         int ret;
  50         struct i2c_client *client = cli;
  51 
  52         ret = i2c_smbus_write_byte(client, cmd);
  53         if (ret) {
  54                 dev_err(&client->dev, "Failed to reset device\n");
  55                 return ret;
  56         }
  57         usleep_range(delay, delay + 1000);
  58 
  59         return 0;
  60 }
  61 EXPORT_SYMBOL(ms_sensors_reset);
  62 
  63 /**
  64  * ms_sensors_read_prom_word() - PROM word read function
  65  * @cli:        pointer to device client
  66  * @cmd:        PROM read cmd. Depends on device and prom id
  67  * @word:       pointer to word destination value
  68  *
  69  * Generic i2c prom word read function for Measurement Specialties devices.
  70  *
  71  * Return: 0 on success, negative errno otherwise.
  72  */
  73 int ms_sensors_read_prom_word(void *cli, int cmd, u16 *word)
  74 {
  75         int ret;
  76         struct i2c_client *client = cli;
  77 
  78         ret = i2c_smbus_read_word_swapped(client, cmd);
  79         if (ret < 0) {
  80                 dev_err(&client->dev, "Failed to read prom word\n");
  81                 return ret;
  82         }
  83         *word = ret;
  84 
  85         return 0;
  86 }
  87 EXPORT_SYMBOL(ms_sensors_read_prom_word);
  88 
  89 /**
  90  * ms_sensors_convert_and_read() - ADC conversion & read function
  91  * @cli:        pointer to device client
  92  * @conv:       ADC conversion command. Depends on device in use
  93  * @rd:         ADC read command. Depends on device in use
  94  * @delay:      usleep minimal delay after conversion command is issued
  95  * @adc:        pointer to ADC destination value
  96  *
  97  * Generic ADC conversion & read function for Measurement Specialties
  98  * devices.
  99  * The function will issue conversion command, sleep appopriate delay, and
 100  * issue command to read ADC.
 101  *
 102  * Return: 0 on success, negative errno otherwise.
 103  */
 104 int ms_sensors_convert_and_read(void *cli, u8 conv, u8 rd,
 105                                 unsigned int delay, u32 *adc)
 106 {
 107         int ret;
 108         __be32 buf = 0;
 109         struct i2c_client *client = cli;
 110 
 111         /* Trigger conversion */
 112         ret = i2c_smbus_write_byte(client, conv);
 113         if (ret)
 114                 goto err;
 115         usleep_range(delay, delay + 1000);
 116 
 117         /* Retrieve ADC value */
 118         if (rd != MS_SENSORS_NO_READ_CMD)
 119                 ret = i2c_smbus_read_i2c_block_data(client, rd, 3, (u8 *)&buf);
 120         else
 121                 ret = i2c_master_recv(client, (u8 *)&buf, 3);
 122         if (ret < 0)
 123                 goto err;
 124 
 125         dev_dbg(&client->dev, "ADC raw value : %x\n", be32_to_cpu(buf) >> 8);
 126         *adc = be32_to_cpu(buf) >> 8;
 127 
 128         return 0;
 129 err:
 130         dev_err(&client->dev, "Unable to make sensor adc conversion\n");
 131         return ret;
 132 }
 133 EXPORT_SYMBOL(ms_sensors_convert_and_read);
 134 
 135 /**
 136  * ms_sensors_crc_valid() - CRC check function
 137  * @value:      input and CRC compare value
 138  *
 139  * Cyclic Redundancy Check function used in TSYS02D, HTU21, MS8607.
 140  * This function performs a x^8 + x^5 + x^4 + 1 polynomial CRC.
 141  * The argument contains CRC value in LSB byte while the bytes 1 and 2
 142  * are used for CRC computation.
 143  *
 144  * Return: 1 if CRC is valid, 0 otherwise.
 145  */
 146 static bool ms_sensors_crc_valid(u32 value)
 147 {
 148         u32 polynom = 0x988000; /* x^8 + x^5 + x^4 + 1 */
 149         u32 msb = 0x800000;
 150         u32 mask = 0xFF8000;
 151         u32 result = value & 0xFFFF00;
 152         u8 crc = value & 0xFF;
 153 
 154         while (msb != 0x80) {
 155                 if (result & msb)
 156                         result = ((result ^ polynom) & mask)
 157                                 | (result & ~mask);
 158                 msb >>= 1;
 159                 mask >>= 1;
 160                 polynom >>= 1;
 161         }
 162 
 163         return result == crc;
 164 }
 165 
 166 /**
 167  * ms_sensors_read_serial() - Serial number read function
 168  * @cli:        pointer to i2c client
 169  * @sn:         pointer to 64-bits destination value
 170  *
 171  * Generic i2c serial number read function for Measurement Specialties devices.
 172  * This function is used for TSYS02d, HTU21, MS8607 chipset.
 173  * Refer to datasheet:
 174  *      http://www.meas-spec.com/downloads/HTU2X_Serial_Number_Reading.pdf
 175  *
 176  * Sensor raw MSB serial number format is the following :
 177  *      [ SNB3, CRC, SNB2, CRC, SNB1, CRC, SNB0, CRC]
 178  * Sensor raw LSB serial number format is the following :
 179  *      [ X, X, SNC1, SNC0, CRC, SNA1, SNA0, CRC]
 180  * The resulting serial number is following :
 181  *      [ SNA1, SNA0, SNB3, SNB2, SNB1, SNB0, SNC1, SNC0]
 182  *
 183  * Return: 0 on success, negative errno otherwise.
 184  */
 185 int ms_sensors_read_serial(struct i2c_client *client, u64 *sn)
 186 {
 187         u8 i;
 188         __be64 rcv_buf = 0;
 189         u64 rcv_val;
 190         __be16 send_buf;
 191         int ret;
 192 
 193         struct i2c_msg msg[2] = {
 194                 {
 195                  .addr = client->addr,
 196                  .flags = client->flags,
 197                  .len = 2,
 198                  .buf = (__u8 *)&send_buf,
 199                  },
 200                 {
 201                  .addr = client->addr,
 202                  .flags = client->flags | I2C_M_RD,
 203                  .buf = (__u8 *)&rcv_buf,
 204                  },
 205         };
 206 
 207         /* Read MSB part of serial number */
 208         send_buf = cpu_to_be16(MS_SENSORS_SERIAL_READ_MSB);
 209         msg[1].len = 8;
 210         ret = i2c_transfer(client->adapter, msg, 2);
 211         if (ret < 0) {
 212                 dev_err(&client->dev, "Unable to read device serial number");
 213                 return ret;
 214         }
 215 
 216         rcv_val = be64_to_cpu(rcv_buf);
 217         dev_dbg(&client->dev, "Serial MSB raw : %llx\n", rcv_val);
 218 
 219         for (i = 0; i < 64; i += 16) {
 220                 if (!ms_sensors_crc_valid((rcv_val >> i) & 0xFFFF))
 221                         return -ENODEV;
 222         }
 223 
 224         *sn = (((rcv_val >> 32) & 0xFF000000) |
 225                ((rcv_val >> 24) & 0x00FF0000) |
 226                ((rcv_val >> 16) & 0x0000FF00) |
 227                ((rcv_val >> 8) & 0x000000FF)) << 16;
 228 
 229         /* Read LSB part of serial number */
 230         send_buf = cpu_to_be16(MS_SENSORS_SERIAL_READ_LSB);
 231         msg[1].len = 6;
 232         rcv_buf = 0;
 233         ret = i2c_transfer(client->adapter, msg, 2);
 234         if (ret < 0) {
 235                 dev_err(&client->dev, "Unable to read device serial number");
 236                 return ret;
 237         }
 238 
 239         rcv_val = be64_to_cpu(rcv_buf) >> 16;
 240         dev_dbg(&client->dev, "Serial MSB raw : %llx\n", rcv_val);
 241 
 242         for (i = 0; i < 48; i += 24) {
 243                 if (!ms_sensors_crc_valid((rcv_val >> i) & 0xFFFFFF))
 244                         return -ENODEV;
 245         }
 246 
 247         *sn |= (rcv_val & 0xFFFF00) << 40 | (rcv_val >> 32);
 248 
 249         return 0;
 250 }
 251 EXPORT_SYMBOL(ms_sensors_read_serial);
 252 
 253 static int ms_sensors_read_config_reg(struct i2c_client *client,
 254                                       u8 *config_reg)
 255 {
 256         int ret;
 257 
 258         ret = i2c_smbus_write_byte(client, MS_SENSORS_CONFIG_REG_READ);
 259         if (ret) {
 260                 dev_err(&client->dev, "Unable to read config register");
 261                 return ret;
 262         }
 263 
 264         ret = i2c_master_recv(client, config_reg, 1);
 265         if (ret < 0) {
 266                 dev_err(&client->dev, "Unable to read config register");
 267                 return ret;
 268         }
 269         dev_dbg(&client->dev, "Config register :%x\n", *config_reg);
 270 
 271         return 0;
 272 }
 273 
 274 /**
 275  * ms_sensors_write_resolution() - Set resolution function
 276  * @dev_data:   pointer to temperature/humidity device data
 277  * @i:          resolution index to set
 278  *
 279  * This function will program the appropriate resolution based on the index
 280  * provided when user space will set samp_freq channel.
 281  * This function is used for TSYS02D, HTU21 and MS8607 chipsets.
 282  *
 283  * Return: 0 on success, negative errno otherwise.
 284  */
 285 ssize_t ms_sensors_write_resolution(struct ms_ht_dev *dev_data,
 286                                     u8 i)
 287 {
 288         u8 config_reg;
 289         int ret;
 290 
 291         ret = ms_sensors_read_config_reg(dev_data->client, &config_reg);
 292         if (ret)
 293                 return ret;
 294 
 295         config_reg &= 0x7E;
 296         config_reg |= ((i & 1) << 7) + ((i & 2) >> 1);
 297 
 298         return i2c_smbus_write_byte_data(dev_data->client,
 299                                          MS_SENSORS_CONFIG_REG_WRITE,
 300                                          config_reg);
 301 }
 302 EXPORT_SYMBOL(ms_sensors_write_resolution);
 303 
 304 /**
 305  * ms_sensors_show_battery_low() - Show device battery low indicator
 306  * @dev_data:   pointer to temperature/humidity device data
 307  * @buf:        pointer to char buffer to write result
 308  *
 309  * This function will read battery indicator value in the device and
 310  * return 1 if the device voltage is below 2.25V.
 311  * This function is used for TSYS02D, HTU21 and MS8607 chipsets.
 312  *
 313  * Return: length of sprintf on success, negative errno otherwise.
 314  */
 315 ssize_t ms_sensors_show_battery_low(struct ms_ht_dev *dev_data,
 316                                     char *buf)
 317 {
 318         int ret;
 319         u8 config_reg;
 320 
 321         mutex_lock(&dev_data->lock);
 322         ret = ms_sensors_read_config_reg(dev_data->client, &config_reg);
 323         mutex_unlock(&dev_data->lock);
 324         if (ret)
 325                 return ret;
 326 
 327         return sprintf(buf, "%d\n", (config_reg & 0x40) >> 6);
 328 }
 329 EXPORT_SYMBOL(ms_sensors_show_battery_low);
 330 
 331 /**
 332  * ms_sensors_show_heater() - Show device heater
 333  * @dev_data:   pointer to temperature/humidity device data
 334  * @buf:        pointer to char buffer to write result
 335  *
 336  * This function will read heater enable value in the device and
 337  * return 1 if the heater is enabled.
 338  * This function is used for HTU21 and MS8607 chipsets.
 339  *
 340  * Return: length of sprintf on success, negative errno otherwise.
 341  */
 342 ssize_t ms_sensors_show_heater(struct ms_ht_dev *dev_data,
 343                                char *buf)
 344 {
 345         u8 config_reg;
 346         int ret;
 347 
 348         mutex_lock(&dev_data->lock);
 349         ret = ms_sensors_read_config_reg(dev_data->client, &config_reg);
 350         mutex_unlock(&dev_data->lock);
 351         if (ret)
 352                 return ret;
 353 
 354         return sprintf(buf, "%d\n", (config_reg & 0x4) >> 2);
 355 }
 356 EXPORT_SYMBOL(ms_sensors_show_heater);
 357 
 358 /**
 359  * ms_sensors_write_heater() - Write device heater
 360  * @dev_data:   pointer to temperature/humidity device data
 361  * @buf:        pointer to char buffer from user space
 362  * @len:        length of buf
 363  *
 364  * This function will write 1 or 0 value in the device
 365  * to enable or disable heater.
 366  * This function is used for HTU21 and MS8607 chipsets.
 367  *
 368  * Return: length of buffer, negative errno otherwise.
 369  */
 370 ssize_t ms_sensors_write_heater(struct ms_ht_dev *dev_data,
 371                                 const char *buf, size_t len)
 372 {
 373         u8 val, config_reg;
 374         int ret;
 375 
 376         ret = kstrtou8(buf, 10, &val);
 377         if (ret)
 378                 return ret;
 379 
 380         if (val > 1)
 381                 return -EINVAL;
 382 
 383         mutex_lock(&dev_data->lock);
 384         ret = ms_sensors_read_config_reg(dev_data->client, &config_reg);
 385         if (ret) {
 386                 mutex_unlock(&dev_data->lock);
 387                 return ret;
 388         }
 389 
 390         config_reg &= 0xFB;
 391         config_reg |= val << 2;
 392 
 393         ret = i2c_smbus_write_byte_data(dev_data->client,
 394                                         MS_SENSORS_CONFIG_REG_WRITE,
 395                                         config_reg);
 396         mutex_unlock(&dev_data->lock);
 397         if (ret) {
 398                 dev_err(&dev_data->client->dev, "Unable to write config register\n");
 399                 return ret;
 400         }
 401 
 402         return len;
 403 }
 404 EXPORT_SYMBOL(ms_sensors_write_heater);
 405 
 406 /**
 407  * ms_sensors_ht_read_temperature() - Read temperature
 408  * @dev_data:   pointer to temperature/humidity device data
 409  * @temperature:pointer to temperature destination value
 410  *
 411  * This function will get temperature ADC value from the device,
 412  * check the CRC and compute the temperature value.
 413  * This function is used for TSYS02D, HTU21 and MS8607 chipsets.
 414  *
 415  * Return: 0 on success, negative errno otherwise.
 416  */
 417 int ms_sensors_ht_read_temperature(struct ms_ht_dev *dev_data,
 418                                    s32 *temperature)
 419 {
 420         int ret;
 421         u32 adc;
 422         u16 delay;
 423 
 424         mutex_lock(&dev_data->lock);
 425         delay = ms_sensors_ht_t_conversion_time[dev_data->res_index];
 426         ret = ms_sensors_convert_and_read(dev_data->client,
 427                                           MS_SENSORS_HT_T_CONVERSION_START,
 428                                           MS_SENSORS_NO_READ_CMD,
 429                                           delay, &adc);
 430         mutex_unlock(&dev_data->lock);
 431         if (ret)
 432                 return ret;
 433 
 434         if (!ms_sensors_crc_valid(adc)) {
 435                 dev_err(&dev_data->client->dev,
 436                         "Temperature read crc check error\n");
 437                 return -ENODEV;
 438         }
 439 
 440         /* Temperature algorithm */
 441         *temperature = (((s64)(adc >> 8) * 175720) >> 16) - 46850;
 442 
 443         return 0;
 444 }
 445 EXPORT_SYMBOL(ms_sensors_ht_read_temperature);
 446 
 447 /**
 448  * ms_sensors_ht_read_humidity() - Read humidity
 449  * @dev_data:   pointer to temperature/humidity device data
 450  * @humidity:   pointer to humidity destination value
 451  *
 452  * This function will get humidity ADC value from the device,
 453  * check the CRC and compute the temperature value.
 454  * This function is used for HTU21 and MS8607 chipsets.
 455  *
 456  * Return: 0 on success, negative errno otherwise.
 457  */
 458 int ms_sensors_ht_read_humidity(struct ms_ht_dev *dev_data,
 459                                 u32 *humidity)
 460 {
 461         int ret;
 462         u32 adc;
 463         u16 delay;
 464 
 465         mutex_lock(&dev_data->lock);
 466         delay = ms_sensors_ht_h_conversion_time[dev_data->res_index];
 467         ret = ms_sensors_convert_and_read(dev_data->client,
 468                                           MS_SENSORS_HT_H_CONVERSION_START,
 469                                           MS_SENSORS_NO_READ_CMD,
 470                                           delay, &adc);
 471         mutex_unlock(&dev_data->lock);
 472         if (ret)
 473                 return ret;
 474 
 475         if (!ms_sensors_crc_valid(adc)) {
 476                 dev_err(&dev_data->client->dev,
 477                         "Humidity read crc check error\n");
 478                 return -ENODEV;
 479         }
 480 
 481         /* Humidity algorithm */
 482         *humidity = (((s32)(adc >> 8) * 12500) >> 16) * 10 - 6000;
 483         if (*humidity >= 100000)
 484                 *humidity = 100000;
 485 
 486         return 0;
 487 }
 488 EXPORT_SYMBOL(ms_sensors_ht_read_humidity);
 489 
 490 /**
 491  * ms_sensors_tp_crc_valid() - CRC check function for
 492  *     Temperature and pressure devices.
 493  *     This function is only used when reading PROM coefficients
 494  *
 495  * @prom:       pointer to PROM coefficients array
 496  * @len:        length of PROM coefficients array
 497  *
 498  * Return: True if CRC is ok.
 499  */
 500 static bool ms_sensors_tp_crc_valid(u16 *prom, u8 len)
 501 {
 502         unsigned int cnt, n_bit;
 503         u16 n_rem = 0x0000, crc_read = prom[0], crc = (*prom & 0xF000) >> 12;
 504 
 505         prom[len - 1] = 0;
 506         prom[0] &= 0x0FFF;      /* Clear the CRC computation part */
 507 
 508         for (cnt = 0; cnt < len * 2; cnt++) {
 509                 if (cnt % 2 == 1)
 510                         n_rem ^= prom[cnt >> 1] & 0x00FF;
 511                 else
 512                         n_rem ^= prom[cnt >> 1] >> 8;
 513 
 514                 for (n_bit = 8; n_bit > 0; n_bit--) {
 515                         if (n_rem & 0x8000)
 516                                 n_rem = (n_rem << 1) ^ 0x3000;
 517                         else
 518                                 n_rem <<= 1;
 519                 }
 520         }
 521         n_rem >>= 12;
 522         prom[0] = crc_read;
 523 
 524         return n_rem == crc;
 525 }
 526 
 527 /**
 528  * ms_sensors_tp_read_prom() - prom coeff read function
 529  * @dev_data:   pointer to temperature/pressure device data
 530  *
 531  * This function will read prom coefficients and check CRC.
 532  * This function is used for MS5637 and MS8607 chipsets.
 533  *
 534  * Return: 0 on success, negative errno otherwise.
 535  */
 536 int ms_sensors_tp_read_prom(struct ms_tp_dev *dev_data)
 537 {
 538         int i, ret;
 539 
 540         for (i = 0; i < MS_SENSORS_TP_PROM_WORDS_NB; i++) {
 541                 ret = ms_sensors_read_prom_word(
 542                         dev_data->client,
 543                         MS_SENSORS_TP_PROM_READ + (i << 1),
 544                         &dev_data->prom[i]);
 545 
 546                 if (ret)
 547                         return ret;
 548         }
 549 
 550         if (!ms_sensors_tp_crc_valid(dev_data->prom,
 551                                      MS_SENSORS_TP_PROM_WORDS_NB + 1)) {
 552                 dev_err(&dev_data->client->dev,
 553                         "Calibration coefficients crc check error\n");
 554                 return -ENODEV;
 555         }
 556 
 557         return 0;
 558 }
 559 EXPORT_SYMBOL(ms_sensors_tp_read_prom);
 560 
 561 /**
 562  * ms_sensors_read_temp_and_pressure() - read temp and pressure
 563  * @dev_data:   pointer to temperature/pressure device data
 564  * @temperature:pointer to temperature destination value
 565  * @pressure:   pointer to pressure destination value
 566  *
 567  * This function will read ADC and compute pressure and temperature value.
 568  * This function is used for MS5637 and MS8607 chipsets.
 569  *
 570  * Return: 0 on success, negative errno otherwise.
 571  */
 572 int ms_sensors_read_temp_and_pressure(struct ms_tp_dev *dev_data,
 573                                       int *temperature,
 574                                       unsigned int *pressure)
 575 {
 576         int ret;
 577         u32 t_adc, p_adc;
 578         s32 dt, temp;
 579         s64 off, sens, t2, off2, sens2;
 580         u16 *prom = dev_data->prom, delay;
 581 
 582         mutex_lock(&dev_data->lock);
 583         delay = ms_sensors_tp_conversion_time[dev_data->res_index];
 584 
 585         ret = ms_sensors_convert_and_read(
 586                                         dev_data->client,
 587                                         MS_SENSORS_TP_T_CONVERSION_START +
 588                                                 dev_data->res_index * 2,
 589                                         MS_SENSORS_TP_ADC_READ,
 590                                         delay, &t_adc);
 591         if (ret) {
 592                 mutex_unlock(&dev_data->lock);
 593                 return ret;
 594         }
 595 
 596         ret = ms_sensors_convert_and_read(
 597                                         dev_data->client,
 598                                         MS_SENSORS_TP_P_CONVERSION_START +
 599                                                 dev_data->res_index * 2,
 600                                         MS_SENSORS_TP_ADC_READ,
 601                                         delay, &p_adc);
 602         mutex_unlock(&dev_data->lock);
 603         if (ret)
 604                 return ret;
 605 
 606         dt = (s32)t_adc - (prom[5] << 8);
 607 
 608         /* Actual temperature = 2000 + dT * TEMPSENS */
 609         temp = 2000 + (((s64)dt * prom[6]) >> 23);
 610 
 611         /* Second order temperature compensation */
 612         if (temp < 2000) {
 613                 s64 tmp = (s64)temp - 2000;
 614 
 615                 t2 = (3 * ((s64)dt * (s64)dt)) >> 33;
 616                 off2 = (61 * tmp * tmp) >> 4;
 617                 sens2 = (29 * tmp * tmp) >> 4;
 618 
 619                 if (temp < -1500) {
 620                         s64 tmp = (s64)temp + 1500;
 621 
 622                         off2 += 17 * tmp * tmp;
 623                         sens2 += 9 * tmp * tmp;
 624                 }
 625         } else {
 626                 t2 = (5 * ((s64)dt * (s64)dt)) >> 38;
 627                 off2 = 0;
 628                 sens2 = 0;
 629         }
 630 
 631         /* OFF = OFF_T1 + TCO * dT */
 632         off = (((s64)prom[2]) << 17) + ((((s64)prom[4]) * (s64)dt) >> 6);
 633         off -= off2;
 634 
 635         /* Sensitivity at actual temperature = SENS_T1 + TCS * dT */
 636         sens = (((s64)prom[1]) << 16) + (((s64)prom[3] * dt) >> 7);
 637         sens -= sens2;
 638 
 639         /* Temperature compensated pressure = D1 * SENS - OFF */
 640         *temperature = (temp - t2) * 10;
 641         *pressure = (u32)(((((s64)p_adc * sens) >> 21) - off) >> 15);
 642 
 643         return 0;
 644 }
 645 EXPORT_SYMBOL(ms_sensors_read_temp_and_pressure);
 646 
 647 MODULE_DESCRIPTION("Measurement-Specialties common i2c driver");
 648 MODULE_AUTHOR("William Markezana <william.markezana@meas-spec.com>");
 649 MODULE_AUTHOR("Ludovic Tancerel <ludovic.tancerel@maplehightech.com>");
 650 MODULE_LICENSE("GPL v2");
 651