drivers/iio/pressure/ms5611_core.c

   1 /*
   2  * MS5611 pressure and temperature sensor driver
   3  *
   4  * Copyright (c) Tomasz Duszynski <tduszyns@gmail.com>
   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  * Data sheet:
  11  *  http://www.meas-spec.com/downloads/MS5611-01BA03.pdf
  12  *  http://www.meas-spec.com/downloads/MS5607-02BA03.pdf
  13  *
  14  */
  15
  16 #include <linux/module.h>
  17 #include <linux/iio/iio.h>
  18 #include <linux/delay.h>
  19
  20 #include "ms5611.h"
  21
  22 static bool ms5611_prom_is_valid(u16 *prom, size_t len)
  23 {
  24         int i, j;
  25         uint16_t crc = 0, crc_orig = prom[7] & 0x000F;
  26
  27         prom[7] &= 0xFF00;
  28
  29         for (i = 0; i < len * 2; i++) {
  30                 if (i % 2 == 1)
  31                         crc ^= prom[i >> 1] & 0x00FF;
  32                 else
  33                         crc ^= prom[i >> 1] >> 8;
  34
  35                 for (j = 0; j < 8; j++) {
  36                         if (crc & 0x8000)
  37                                 crc = (crc << 1) ^ 0x3000;
  38                         else
  39                                 crc <<= 1;
  40                 }
  41         }
  42
  43         crc = (crc >> 12) & 0x000F;
  44
  45         return crc_orig != 0x0000 && crc == crc_orig;
  46 }
  47
  48 static int ms5611_read_prom(struct iio_dev *indio_dev)
  49 {
  50         int ret, i;
  51         struct ms5611_state *st = iio_priv(indio_dev);
  52
  53         for (i = 0; i < MS5611_PROM_WORDS_NB; i++) {
  54                 ret = st->read_prom_word(&indio_dev->dev,
  55                                          i, &st->chip_info->prom[i]);
  56                 if (ret < 0) {
  57                         dev_err(&indio_dev->dev,
  58                                 "failed to read prom at %d\n", i);
  59                         return ret;
  60                 }
  61         }
  62
  63         if (!ms5611_prom_is_valid(st->chip_info->prom, MS5611_PROM_WORDS_NB)) {
  64                 dev_err(&indio_dev->dev, "PROM integrity check failed\n");
  65                 return -ENODEV;
  66         }
  67
  68         return 0;
  69 }
  70
  71 static int ms5611_read_temp_and_pressure(struct iio_dev *indio_dev,
  72                                          s32 *temp, s32 *pressure)
  73 {
  74         int ret;
  75         struct ms5611_state *st = iio_priv(indio_dev);
  76
  77         ret = st->read_adc_temp_and_pressure(&indio_dev->dev, temp, pressure);
  78         if (ret < 0) {
  79                 dev_err(&indio_dev->dev,
  80                         "failed to read temperature and pressure\n");
  81                 return ret;
  82         }
  83
  84         return st->chip_info->temp_and_pressure_compensate(st->chip_info,
  85                                                            temp, pressure);
  86 }
  87
  88 static int ms5611_temp_and_pressure_compensate(struct ms5611_chip_info *chip_info,
  89                                                s32 *temp, s32 *pressure)
  90 {
  91         s32 t = *temp, p = *pressure;
  92         s64 off, sens, dt;
  93
  94         dt = t - (chip_info->prom[5] << 8);
  95         off = ((s64)chip_info->prom[2] << 16) + ((chip_info->prom[4] * dt) >> 7);
  96         sens = ((s64)chip_info->prom[1] << 15) + ((chip_info->prom[3] * dt) >> 8);
  97
  98         t = 2000 + ((chip_info->prom[6] * dt) >> 23);
  99         if (t < 2000) {
 100                 s64 off2, sens2, t2;
 101
 102                 t2 = (dt * dt) >> 31;
 103                 off2 = (5 * (t - 2000) * (t - 2000)) >> 1;
 104                 sens2 = off2 >> 1;
 105
 106                 if (t < -1500) {
 107                         s64 tmp = (t + 1500) * (t + 1500);
 108
 109                         off2 += 7 * tmp;
 110                         sens2 += (11 * tmp) >> 1;
 111                 }
 112
 113                 t -= t2;
 114                 off -= off2;
 115                 sens -= sens2;
 116         }
 117
 118         *temp = t;
 119         *pressure = (((p * sens) >> 21) - off) >> 15;
 120
 121         return 0;
 122 }
 123
 124 static int ms5607_temp_and_pressure_compensate(struct ms5611_chip_info *chip_info,
 125                                                s32 *temp, s32 *pressure)
 126 {
 127         s32 t = *temp, p = *pressure;
 128         s64 off, sens, dt;
 129
 130         dt = t - (chip_info->prom[5] << 8);
 131         off = ((s64)chip_info->prom[2] << 17) + ((chip_info->prom[4] * dt) >> 6);
 132         sens = ((s64)chip_info->prom[1] << 16) + ((chip_info->prom[3] * dt) >> 7);
 133
 134         t = 2000 + ((chip_info->prom[6] * dt) >> 23);
 135         if (t < 2000) {
 136                 s64 off2, sens2, t2;
 137
 138                 t2 = (dt * dt) >> 31;
 139                 off2 = (61 * (t - 2000) * (t - 2000)) >> 4;
 140                 sens2 = off2 << 1;
 141
 142                 if (t < -1500) {
 143                         s64 tmp = (t + 1500) * (t + 1500);
 144
 145                         off2 += 15 * tmp;
 146                         sens2 += (8 * tmp);
 147                 }
 148
 149                 t -= t2;
 150                 off -= off2;
 151                 sens -= sens2;
 152         }
 153
 154         *temp = t;
 155         *pressure = (((p * sens) >> 21) - off) >> 15;
 156
 157         return 0;
 158 }
 159
 160 static int ms5611_reset(struct iio_dev *indio_dev)
 161 {
 162         int ret;
 163         struct ms5611_state *st = iio_priv(indio_dev);
 164
 165         ret = st->reset(&indio_dev->dev);
 166         if (ret < 0) {
 167                 dev_err(&indio_dev->dev, "failed to reset device\n");
 168                 return ret;
 169         }
 170
 171         usleep_range(3000, 4000);
 172
 173         return 0;
 174 }
 175
 176 static int ms5611_read_raw(struct iio_dev *indio_dev,
 177                            struct iio_chan_spec const *chan,
 178                            int *val, int *val2, long mask)
 179 {
 180         int ret;
 181         s32 temp, pressure;
 182         struct ms5611_state *st = iio_priv(indio_dev);
 183
 184         switch (mask) {
 185         case IIO_CHAN_INFO_PROCESSED:
 186                 mutex_lock(&st->lock);
 187                 ret = ms5611_read_temp_and_pressure(indio_dev,
 188                                                     &temp, &pressure);
 189                 mutex_unlock(&st->lock);
 190                 if (ret < 0)
 191                         return ret;
 192
 193                 switch (chan->type) {
 194                 case IIO_TEMP:
 195                         *val = temp * 10;
 196                         return IIO_VAL_INT;
 197                 case IIO_PRESSURE:
 198                         *val = pressure / 1000;
 199                         *val2 = (pressure % 1000) * 1000;
 200                         return IIO_VAL_INT_PLUS_MICRO;
 201                 default:
 202                         return -EINVAL;
 203                 }
 204         }
 205
 206         return -EINVAL;
 207 }
 208
 209 static struct ms5611_chip_info chip_info_tbl[] = {
 210         [MS5611] = {
 211                 .temp_and_pressure_compensate = ms5611_temp_and_pressure_compensate,
 212         },
 213         [MS5607] = {
 214                 .temp_and_pressure_compensate = ms5607_temp_and_pressure_compensate,
 215         }
 216 };
 217
 218 static const struct iio_chan_spec ms5611_channels[] = {
 219         {
 220                 .type = IIO_PRESSURE,
 221                 .info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
 222         },
 223         {
 224                 .type = IIO_TEMP,
 225                 .info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
 226         }
 227 };
 228
 229 static const struct iio_info ms5611_info = {
 230         .read_raw = &ms5611_read_raw,
 231         .driver_module = THIS_MODULE,
 232 };
 233
 234 static int ms5611_init(struct iio_dev *indio_dev)
 235 {
 236         int ret;
 237
 238         ret = ms5611_reset(indio_dev);
 239         if (ret < 0)
 240                 return ret;
 241
 242         return ms5611_read_prom(indio_dev);
 243 }
 244
 245 int ms5611_probe(struct iio_dev *indio_dev, struct device *dev, int type)
 246 {
 247         int ret;
 248         struct ms5611_state *st = iio_priv(indio_dev);
 249
 250         mutex_init(&st->lock);
 251         st->chip_info = &chip_info_tbl[type];
 252         indio_dev->dev.parent = dev;
 253         indio_dev->name = dev->driver->name;
 254         indio_dev->info = &ms5611_info;
 255         indio_dev->channels = ms5611_channels;
 256         indio_dev->num_channels = ARRAY_SIZE(ms5611_channels);
 257         indio_dev->modes = INDIO_DIRECT_MODE;
 258
 259         ret = ms5611_init(indio_dev);
 260         if (ret < 0)
 261                 return ret;
 262
 263         return devm_iio_device_register(dev, indio_dev);
 264 }
 265 EXPORT_SYMBOL(ms5611_probe);
 266
 267 MODULE_AUTHOR("Tomasz Duszynski <tduszyns@gmail.com>");
 268 MODULE_DESCRIPTION("MS5611 core driver");
 269 MODULE_LICENSE("GPL v2");