drivers/iio/accel/adxl345_core.c

   1 /*
   2  * ADXL345 3-Axis Digital Accelerometer IIO core driver
   3  *
   4  * Copyright (c) 2017 Eva Rachel Retuya <eraretuya@gmail.com>
   5  *
   6  * This file is subject to the terms and conditions of version 2 of
   7  * the GNU General Public License. See the file COPYING in the main
   8  * directory of this archive for more details.
   9  */
  10
  11 #include <linux/module.h>
  12 #include <linux/regmap.h>
  13
  14 #include <linux/iio/iio.h>
  15
  16 #include "adxl345.h"
  17
  18 #define ADXL345_REG_DEVID               0x00
  19 #define ADXL345_REG_POWER_CTL           0x2D
  20 #define ADXL345_REG_DATA_FORMAT         0x31
  21 #define ADXL345_REG_DATAX0              0x32
  22 #define ADXL345_REG_DATAY0              0x34
  23 #define ADXL345_REG_DATAZ0              0x36
  24
  25 #define ADXL345_POWER_CTL_MEASURE       BIT(3)
  26 #define ADXL345_POWER_CTL_STANDBY       0x00
  27
  28 #define ADXL345_DATA_FORMAT_FULL_RES    BIT(3) /* Up to 13-bits resolution */
  29 #define ADXL345_DATA_FORMAT_2G          0
  30 #define ADXL345_DATA_FORMAT_4G          1
  31 #define ADXL345_DATA_FORMAT_8G          2
  32 #define ADXL345_DATA_FORMAT_16G         3
  33
  34 #define ADXL345_DEVID                   0xE5
  35
  36 /*
  37  * In full-resolution mode, scale factor is maintained at ~4 mg/LSB
  38  * in all g ranges.
  39  *
  40  * At +/- 16g with 13-bit resolution, scale is computed as:
  41  * (16 + 16) * 9.81 / (2^13 - 1) = 0.0383
  42  */
  43 static const int adxl345_uscale = 38300;
  44
  45 struct adxl345_data {
  46         struct regmap *regmap;
  47         u8 data_range;
  48 };
  49
  50 #define ADXL345_CHANNEL(reg, axis) {                                    \
  51         .type = IIO_ACCEL,                                              \
  52         .modified = 1,                                                  \
  53         .channel2 = IIO_MOD_##axis,                                     \
  54         .address = reg,                                                 \
  55         .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),                   \
  56         .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),           \
  57 }
  58
  59 static const struct iio_chan_spec adxl345_channels[] = {
  60         ADXL345_CHANNEL(ADXL345_REG_DATAX0, X),
  61         ADXL345_CHANNEL(ADXL345_REG_DATAY0, Y),
  62         ADXL345_CHANNEL(ADXL345_REG_DATAZ0, Z),
  63 };
  64
  65 static int adxl345_read_raw(struct iio_dev *indio_dev,
  66                             struct iio_chan_spec const *chan,
  67                             int *val, int *val2, long mask)
  68 {
  69         struct adxl345_data *data = iio_priv(indio_dev);
  70         __le16 regval;
  71         int ret;
  72
  73         switch (mask) {
  74         case IIO_CHAN_INFO_RAW:
  75                 /*
  76                  * Data is stored in adjacent registers:
  77                  * ADXL345_REG_DATA(X0/Y0/Z0) contain the least significant byte
  78                  * and ADXL345_REG_DATA(X0/Y0/Z0) + 1 the most significant byte
  79                  */
  80                 ret = regmap_bulk_read(data->regmap, chan->address, &regval,
  81                                        sizeof(regval));
  82                 if (ret < 0)
  83                         return ret;
  84
  85                 *val = sign_extend32(le16_to_cpu(regval), 12);
  86                 return IIO_VAL_INT;
  87         case IIO_CHAN_INFO_SCALE:
  88                 *val = 0;
  89                 *val2 = adxl345_uscale;
  90
  91                 return IIO_VAL_INT_PLUS_MICRO;
  92         }
  93
  94         return -EINVAL;
  95 }
  96
  97 static const struct iio_info adxl345_info = {
  98         .driver_module  = THIS_MODULE,
  99         .read_raw       = adxl345_read_raw,
 100 };
 101
 102 int adxl345_core_probe(struct device *dev, struct regmap *regmap,
 103                        const char *name)
 104 {
 105         struct adxl345_data *data;
 106         struct iio_dev *indio_dev;
 107         u32 regval;
 108         int ret;
 109
 110         ret = regmap_read(regmap, ADXL345_REG_DEVID, &regval);
 111         if (ret < 0) {
 112                 dev_err(dev, "Error reading device ID: %d\n", ret);
 113                 return ret;
 114         }
 115
 116         if (regval != ADXL345_DEVID) {
 117                 dev_err(dev, "Invalid device ID: %x, expected %x\n",
 118                         regval, ADXL345_DEVID);
 119                 return -ENODEV;
 120         }
 121
 122         indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
 123         if (!indio_dev)
 124                 return -ENOMEM;
 125
 126         data = iio_priv(indio_dev);
 127         dev_set_drvdata(dev, indio_dev);
 128         data->regmap = regmap;
 129         /* Enable full-resolution mode */
 130         data->data_range = ADXL345_DATA_FORMAT_FULL_RES;
 131
 132         ret = regmap_write(data->regmap, ADXL345_REG_DATA_FORMAT,
 133                            data->data_range);
 134         if (ret < 0) {
 135                 dev_err(dev, "Failed to set data range: %d\n", ret);
 136                 return ret;
 137         }
 138
 139         indio_dev->dev.parent = dev;
 140         indio_dev->name = name;
 141         indio_dev->info = &adxl345_info;
 142         indio_dev->modes = INDIO_DIRECT_MODE;
 143         indio_dev->channels = adxl345_channels;
 144         indio_dev->num_channels = ARRAY_SIZE(adxl345_channels);
 145
 146         /* Enable measurement mode */
 147         ret = regmap_write(data->regmap, ADXL345_REG_POWER_CTL,
 148                            ADXL345_POWER_CTL_MEASURE);
 149         if (ret < 0) {
 150                 dev_err(dev, "Failed to enable measurement mode: %d\n", ret);
 151                 return ret;
 152         }
 153
 154         ret = iio_device_register(indio_dev);
 155         if (ret < 0) {
 156                 dev_err(dev, "iio_device_register failed: %d\n", ret);
 157                 regmap_write(data->regmap, ADXL345_REG_POWER_CTL,
 158                              ADXL345_POWER_CTL_STANDBY);
 159         }
 160
 161         return ret;
 162 }
 163 EXPORT_SYMBOL_GPL(adxl345_core_probe);
 164
 165 int adxl345_core_remove(struct device *dev)
 166 {
 167         struct iio_dev *indio_dev = dev_get_drvdata(dev);
 168         struct adxl345_data *data = iio_priv(indio_dev);
 169
 170         iio_device_unregister(indio_dev);
 171
 172         return regmap_write(data->regmap, ADXL345_REG_POWER_CTL,
 173                             ADXL345_POWER_CTL_STANDBY);
 174 }
 175 EXPORT_SYMBOL_GPL(adxl345_core_remove);
 176
 177 MODULE_AUTHOR("Eva Rachel Retuya <eraretuya@gmail.com>");
 178 MODULE_DESCRIPTION("ADXL345 3-Axis Digital Accelerometer core driver");
 179 MODULE_LICENSE("GPL v2");