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         .read_raw       = adxl345_read_raw,
  99 };
 100
 101 int adxl345_core_probe(struct device *dev, struct regmap *regmap,
 102                        const char *name)
 103 {
 104         struct adxl345_data *data;
 105         struct iio_dev *indio_dev;
 106         u32 regval;
 107         int ret;
 108
 109         ret = regmap_read(regmap, ADXL345_REG_DEVID, &regval);
 110         if (ret < 0) {
 111                 dev_err(dev, "Error reading device ID: %d\n", ret);
 112                 return ret;
 113         }
 114
 115         if (regval != ADXL345_DEVID) {
 116                 dev_err(dev, "Invalid device ID: %x, expected %x\n",
 117                         regval, ADXL345_DEVID);
 118                 return -ENODEV;
 119         }
 120
 121         indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
 122         if (!indio_dev)
 123                 return -ENOMEM;
 124
 125         data = iio_priv(indio_dev);
 126         dev_set_drvdata(dev, indio_dev);
 127         data->regmap = regmap;
 128         /* Enable full-resolution mode */
 129         data->data_range = ADXL345_DATA_FORMAT_FULL_RES;
 130
 131         ret = regmap_write(data->regmap, ADXL345_REG_DATA_FORMAT,
 132                            data->data_range);
 133         if (ret < 0) {
 134                 dev_err(dev, "Failed to set data range: %d\n", ret);
 135                 return ret;
 136         }
 137
 138         indio_dev->dev.parent = dev;
 139         indio_dev->name = name;
 140         indio_dev->info = &adxl345_info;
 141         indio_dev->modes = INDIO_DIRECT_MODE;
 142         indio_dev->channels = adxl345_channels;
 143         indio_dev->num_channels = ARRAY_SIZE(adxl345_channels);
 144
 145         /* Enable measurement mode */
 146         ret = regmap_write(data->regmap, ADXL345_REG_POWER_CTL,
 147                            ADXL345_POWER_CTL_MEASURE);
 148         if (ret < 0) {
 149                 dev_err(dev, "Failed to enable measurement mode: %d\n", ret);
 150                 return ret;
 151         }
 152
 153         ret = iio_device_register(indio_dev);
 154         if (ret < 0) {
 155                 dev_err(dev, "iio_device_register failed: %d\n", ret);
 156                 regmap_write(data->regmap, ADXL345_REG_POWER_CTL,
 157                              ADXL345_POWER_CTL_STANDBY);
 158         }
 159
 160         return ret;
 161 }
 162 EXPORT_SYMBOL_GPL(adxl345_core_probe);
 163
 164 int adxl345_core_remove(struct device *dev)
 165 {
 166         struct iio_dev *indio_dev = dev_get_drvdata(dev);
 167         struct adxl345_data *data = iio_priv(indio_dev);
 168
 169         iio_device_unregister(indio_dev);
 170
 171         return regmap_write(data->regmap, ADXL345_REG_POWER_CTL,
 172                             ADXL345_POWER_CTL_STANDBY);
 173 }
 174 EXPORT_SYMBOL_GPL(adxl345_core_remove);
 175
 176 MODULE_AUTHOR("Eva Rachel Retuya <eraretuya@gmail.com>");
 177 MODULE_DESCRIPTION("ADXL345 3-Axis Digital Accelerometer core driver");
 178 MODULE_LICENSE("GPL v2");