drivers/iio/accel/dmard09.c

   1 /*
   2  * IIO driver for the 3-axis accelerometer Domintech DMARD09.
   3  *
   4  * Copyright (c) 2016, Jelle van der Waa <jelle@vdwaa.nl>
   5  *
   6  * This program is free software; you can redistribute it and/or modify it
   7  * under the terms and conditions of the GNU General Public License,
   8  * version 2, as published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope it will be useful, but WITHOUT
  11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  12  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  13  * more details.
  14  */
  15
  16 #include <asm/unaligned.h>
  17 #include <linux/module.h>
  18 #include <linux/i2c.h>
  19 #include <linux/iio/iio.h>
  20
  21 #define DMARD09_DRV_NAME        "dmard09"
  22
  23 #define DMARD09_REG_CHIPID      0x18
  24 #define DMARD09_REG_STAT        0x0A
  25 #define DMARD09_REG_X           0x0C
  26 #define DMARD09_REG_Y           0x0E
  27 #define DMARD09_REG_Z           0x10
  28 #define DMARD09_CHIPID          0x95
  29
  30 #define DMARD09_BUF_LEN 8
  31 #define DMARD09_AXIS_X 0
  32 #define DMARD09_AXIS_Y 1
  33 #define DMARD09_AXIS_Z 2
  34 #define DMARD09_AXIS_X_OFFSET ((DMARD09_AXIS_X + 1) * 2)
  35 #define DMARD09_AXIS_Y_OFFSET ((DMARD09_AXIS_Y + 1 )* 2)
  36 #define DMARD09_AXIS_Z_OFFSET ((DMARD09_AXIS_Z + 1) * 2)
  37
  38 struct dmard09_data {
  39         struct i2c_client *client;
  40 };
  41
  42 #define DMARD09_CHANNEL(_axis, offset) {                        \
  43         .type = IIO_ACCEL,                                      \
  44         .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),           \
  45         .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),   \
  46         .modified = 1,                                          \
  47         .address = offset,                                      \
  48         .channel2 = IIO_MOD_##_axis,                            \
  49 }
  50
  51 static const struct iio_chan_spec dmard09_channels[] = {
  52         DMARD09_CHANNEL(X, DMARD09_AXIS_X_OFFSET),
  53         DMARD09_CHANNEL(Y, DMARD09_AXIS_Y_OFFSET),
  54         DMARD09_CHANNEL(Z, DMARD09_AXIS_Z_OFFSET),
  55 };
  56
  57 static int dmard09_read_raw(struct iio_dev *indio_dev,
  58                             struct iio_chan_spec const *chan,
  59                             int *val, int *val2, long mask)
  60 {
  61         struct dmard09_data *data = iio_priv(indio_dev);
  62         u8 buf[DMARD09_BUF_LEN];
  63         int ret;
  64         s16 accel;
  65
  66         switch (mask) {
  67         case IIO_CHAN_INFO_RAW:
  68                 /*
  69                  * Read from the DMAR09_REG_STAT register, since the chip
  70                  * caches reads from the individual X, Y, Z registers.
  71                  */
  72                 ret = i2c_smbus_read_i2c_block_data(data->client,
  73                                                     DMARD09_REG_STAT,
  74                                                     DMARD09_BUF_LEN, buf);
  75                 if (ret < 0) {
  76                         dev_err(&data->client->dev, "Error reading reg %d\n",
  77                                 DMARD09_REG_STAT);
  78                         return ret;
  79                 }
  80
  81                 accel = get_unaligned_le16(&buf[chan->address]);
  82
  83                 /* Remove lower 3 bits and sign extend */
  84                 accel <<= 4;
  85                 accel >>= 7;
  86
  87                 *val = accel;
  88
  89                 return IIO_VAL_INT;
  90         default:
  91                 return -EINVAL;
  92         }
  93 }
  94
  95 static const struct iio_info dmard09_info = {
  96         .read_raw       = dmard09_read_raw,
  97 };
  98
  99 static int dmard09_probe(struct i2c_client *client,
 100                         const struct i2c_device_id *id)
 101 {
 102         int ret;
 103         struct iio_dev *indio_dev;
 104         struct dmard09_data *data;
 105
 106         indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
 107         if (!indio_dev) {
 108                 dev_err(&client->dev, "iio allocation failed\n");
 109                 return -ENOMEM;
 110         }
 111
 112         data = iio_priv(indio_dev);
 113         data->client = client;
 114
 115         ret = i2c_smbus_read_byte_data(data->client, DMARD09_REG_CHIPID);
 116         if (ret < 0) {
 117                 dev_err(&client->dev, "Error reading chip id %d\n", ret);
 118                 return ret;
 119         }
 120
 121         if (ret != DMARD09_CHIPID) {
 122                 dev_err(&client->dev, "Invalid chip id %d\n", ret);
 123                 return -ENODEV;
 124         }
 125
 126         i2c_set_clientdata(client, indio_dev);
 127         indio_dev->dev.parent = &client->dev;
 128         indio_dev->name = DMARD09_DRV_NAME;
 129         indio_dev->modes = INDIO_DIRECT_MODE;
 130         indio_dev->channels = dmard09_channels;
 131         indio_dev->num_channels = ARRAY_SIZE(dmard09_channels);
 132         indio_dev->info = &dmard09_info;
 133
 134         return devm_iio_device_register(&client->dev, indio_dev);
 135 }
 136
 137 static const struct i2c_device_id dmard09_id[] = {
 138         { "dmard09", 0},
 139         { },
 140 };
 141
 142 MODULE_DEVICE_TABLE(i2c, dmard09_id);
 143
 144 static struct i2c_driver dmard09_driver = {
 145         .driver = {
 146                 .name = DMARD09_DRV_NAME
 147         },
 148         .probe = dmard09_probe,
 149         .id_table = dmard09_id,
 150 };
 151
 152 module_i2c_driver(dmard09_driver);
 153
 154 MODULE_AUTHOR("Jelle van der Waa <jelle@vdwaa.nl>");
 155 MODULE_DESCRIPTION("DMARD09 3-axis accelerometer driver");
 156 MODULE_LICENSE("GPL");