drivers/iio/pressure/mpl115.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * mpl115.c - Support for Freescale MPL115A pressure/temperature sensor
   4  *
   5  * Copyright (c) 2014 Peter Meerwald <pmeerw@pmeerw.net>
   6  *
   7  * TODO: shutdown pin
   8  */
   9
  10 #include <linux/module.h>
  11 #include <linux/iio/iio.h>
  12 #include <linux/delay.h>
  13
  14 #include "mpl115.h"
  15
  16 #define MPL115_PADC 0x00 /* pressure ADC output value, MSB first, 10 bit */
  17 #define MPL115_TADC 0x02 /* temperature ADC output value, MSB first, 10 bit */
  18 #define MPL115_A0 0x04 /* 12 bit integer, 3 bit fraction */
  19 #define MPL115_B1 0x06 /* 2 bit integer, 13 bit fraction */
  20 #define MPL115_B2 0x08 /* 1 bit integer, 14 bit fraction */
  21 #define MPL115_C12 0x0a /* 0 bit integer, 13 bit fraction */
  22 #define MPL115_CONVERT 0x12 /* convert temperature and pressure */
  23
  24 struct mpl115_data {
  25         struct device *dev;
  26         struct mutex lock;
  27         s16 a0;
  28         s16 b1, b2;
  29         s16 c12;
  30         const struct mpl115_ops *ops;
  31 };
  32
  33 static int mpl115_request(struct mpl115_data *data)
  34 {
  35         int ret = data->ops->write(data->dev, MPL115_CONVERT, 0);
  36
  37         if (ret < 0)
  38                 return ret;
  39
  40         usleep_range(3000, 4000);
  41
  42         return 0;
  43 }
  44
  45 static int mpl115_comp_pressure(struct mpl115_data *data, int *val, int *val2)
  46 {
  47         int ret;
  48         u16 padc, tadc;
  49         int a1, y1, pcomp;
  50         unsigned kpa;
  51
  52         mutex_lock(&data->lock);
  53         ret = mpl115_request(data);
  54         if (ret < 0)
  55                 goto done;
  56
  57         ret = data->ops->read(data->dev, MPL115_PADC);
  58         if (ret < 0)
  59                 goto done;
  60         padc = ret >> 6;
  61
  62         ret = data->ops->read(data->dev, MPL115_TADC);
  63         if (ret < 0)
  64                 goto done;
  65         tadc = ret >> 6;
  66
  67         /* see Freescale AN3785 */
  68         a1 = data->b1 + ((data->c12 * tadc) >> 11);
  69         y1 = (data->a0 << 10) + a1 * padc;
  70
  71         /* compensated pressure with 4 fractional bits */
  72         pcomp = (y1 + ((data->b2 * (int) tadc) >> 1)) >> 9;
  73
  74         kpa = pcomp * (115 - 50) / 1023 + (50 << 4);
  75         *val = kpa >> 4;
  76         *val2 = (kpa & 15) * (1000000 >> 4);
  77 done:
  78         mutex_unlock(&data->lock);
  79         return ret;
  80 }
  81
  82 static int mpl115_read_temp(struct mpl115_data *data)
  83 {
  84         int ret;
  85
  86         mutex_lock(&data->lock);
  87         ret = mpl115_request(data);
  88         if (ret < 0)
  89                 goto done;
  90         ret = data->ops->read(data->dev, MPL115_TADC);
  91 done:
  92         mutex_unlock(&data->lock);
  93         return ret;
  94 }
  95
  96 static int mpl115_read_raw(struct iio_dev *indio_dev,
  97                             struct iio_chan_spec const *chan,
  98                             int *val, int *val2, long mask)
  99 {
 100         struct mpl115_data *data = iio_priv(indio_dev);
 101         int ret;
 102
 103         switch (mask) {
 104         case IIO_CHAN_INFO_PROCESSED:
 105                 ret = mpl115_comp_pressure(data, val, val2);
 106                 if (ret < 0)
 107                         return ret;
 108                 return IIO_VAL_INT_PLUS_MICRO;
 109         case IIO_CHAN_INFO_RAW:
 110                 /* temperature -5.35 C / LSB, 472 LSB is 25 C */
 111                 ret = mpl115_read_temp(data);
 112                 if (ret < 0)
 113                         return ret;
 114                 *val = ret >> 6;
 115                 return IIO_VAL_INT;
 116         case IIO_CHAN_INFO_OFFSET:
 117                 *val = -605;
 118                 *val2 = 750000;
 119                 return IIO_VAL_INT_PLUS_MICRO;
 120         case IIO_CHAN_INFO_SCALE:
 121                 *val = -186;
 122                 *val2 = 915888;
 123                 return IIO_VAL_INT_PLUS_MICRO;
 124         }
 125         return -EINVAL;
 126 }
 127
 128 static const struct iio_chan_spec mpl115_channels[] = {
 129         {
 130                 .type = IIO_PRESSURE,
 131                 .info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
 132         },
 133         {
 134                 .type = IIO_TEMP,
 135                 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
 136                 .info_mask_shared_by_type =
 137                         BIT(IIO_CHAN_INFO_OFFSET) | BIT(IIO_CHAN_INFO_SCALE),
 138         },
 139 };
 140
 141 static const struct iio_info mpl115_info = {
 142         .read_raw = &mpl115_read_raw,
 143 };
 144
 145 int mpl115_probe(struct device *dev, const char *name,
 146                         const struct mpl115_ops *ops)
 147 {
 148         struct mpl115_data *data;
 149         struct iio_dev *indio_dev;
 150         int ret;
 151
 152         indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
 153         if (!indio_dev)
 154                 return -ENOMEM;
 155
 156         data = iio_priv(indio_dev);
 157         data->dev = dev;
 158         data->ops = ops;
 159         mutex_init(&data->lock);
 160
 161         indio_dev->info = &mpl115_info;
 162         indio_dev->name = name;
 163         indio_dev->dev.parent = dev;
 164         indio_dev->modes = INDIO_DIRECT_MODE;
 165         indio_dev->channels = mpl115_channels;
 166         indio_dev->num_channels = ARRAY_SIZE(mpl115_channels);
 167
 168         ret = data->ops->init(data->dev);
 169         if (ret)
 170                 return ret;
 171
 172         ret = data->ops->read(data->dev, MPL115_A0);
 173         if (ret < 0)
 174                 return ret;
 175         data->a0 = ret;
 176         ret = data->ops->read(data->dev, MPL115_B1);
 177         if (ret < 0)
 178                 return ret;
 179         data->b1 = ret;
 180         ret = data->ops->read(data->dev, MPL115_B2);
 181         if (ret < 0)
 182                 return ret;
 183         data->b2 = ret;
 184         ret = data->ops->read(data->dev, MPL115_C12);
 185         if (ret < 0)
 186                 return ret;
 187         data->c12 = ret;
 188
 189         return devm_iio_device_register(dev, indio_dev);
 190 }
 191 EXPORT_SYMBOL_GPL(mpl115_probe);
 192
 193 MODULE_AUTHOR("Peter Meerwald <pmeerw@pmeerw.net>");
 194 MODULE_DESCRIPTION("Freescale MPL115 pressure/temperature driver");
 195 MODULE_LICENSE("GPL");