drivers/iio/accel/mxc6255.c

   1 /*
   2  * MXC6255 - MEMSIC orientation sensing accelerometer
   3  *
   4  * Copyright (c) 2015, Intel Corporation.
   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  * IIO driver for MXC6255 (7-bit I2C slave address 0x15).
  11  */
  12
  13 #include <linux/module.h>
  14 #include <linux/i2c.h>
  15 #include <linux/init.h>
  16 #include <linux/iio/iio.h>
  17 #include <linux/delay.h>
  18 #include <linux/acpi.h>
  19 #include <linux/regmap.h>
  20 #include <linux/iio/sysfs.h>
  21
  22 #define MXC6255_DRV_NAME                "mxc6255"
  23 #define MXC6255_REGMAP_NAME             "mxc6255_regmap"
  24
  25 #define MXC6255_REG_XOUT                0x00
  26 #define MXC6255_REG_YOUT                0x01
  27 #define MXC6255_REG_CHIP_ID             0x08
  28
  29 #define MXC6255_CHIP_ID                 0x05
  30
  31 /*
  32  * MXC6255 has only one measurement range: +/- 2G.
  33  * The acceleration output is an 8-bit value.
  34  *
  35  * Scale is calculated as follows:
  36  * (2 + 2) * 9.80665 / (2^8 - 1) = 0.153829
  37  *
  38  * Scale value for +/- 2G measurement range
  39  */
  40 #define MXC6255_SCALE                   153829
  41
  42 enum mxc6255_axis {
  43         AXIS_X,
  44         AXIS_Y,
  45 };
  46
  47 struct mxc6255_data {
  48         struct i2c_client *client;
  49         struct regmap *regmap;
  50 };
  51
  52 static int mxc6255_read_raw(struct iio_dev *indio_dev,
  53                             struct iio_chan_spec const *chan,
  54                             int *val, int *val2, long mask)
  55 {
  56         struct mxc6255_data *data = iio_priv(indio_dev);
  57         unsigned int reg;
  58         int ret;
  59
  60         switch (mask) {
  61         case IIO_CHAN_INFO_RAW:
  62                 ret = regmap_read(data->regmap, chan->address, &reg);
  63                 if (ret < 0) {
  64                         dev_err(&data->client->dev,
  65                                 "Error reading reg %lu\n", chan->address);
  66                         return ret;
  67                 }
  68
  69                 *val = sign_extend32(reg, 7);
  70                 return IIO_VAL_INT;
  71         case IIO_CHAN_INFO_SCALE:
  72                 *val = 0;
  73                 *val2 = MXC6255_SCALE;
  74                 return IIO_VAL_INT_PLUS_MICRO;
  75         default:
  76                 return -EINVAL;
  77         }
  78 }
  79
  80 static const struct iio_info mxc6255_info = {
  81         .driver_module  = THIS_MODULE,
  82         .read_raw       = mxc6255_read_raw,
  83 };
  84
  85 #define MXC6255_CHANNEL(_axis, reg) {                           \
  86         .type = IIO_ACCEL,                                      \
  87         .modified = 1,                                          \
  88         .channel2 = IIO_MOD_##_axis,                            \
  89         .address = reg,                                         \
  90         .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),           \
  91         .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),   \
  92 }
  93
  94 static const struct iio_chan_spec mxc6255_channels[] = {
  95         MXC6255_CHANNEL(X, MXC6255_REG_XOUT),
  96         MXC6255_CHANNEL(Y, MXC6255_REG_YOUT),
  97 };
  98
  99 static bool mxc6255_is_readable_reg(struct device *dev, unsigned int reg)
 100 {
 101         switch (reg) {
 102         case MXC6255_REG_XOUT:
 103         case MXC6255_REG_YOUT:
 104         case MXC6255_REG_CHIP_ID:
 105                 return true;
 106         default:
 107                 return false;
 108         }
 109 }
 110
 111 static const struct regmap_config mxc6255_regmap_config = {
 112         .name = MXC6255_REGMAP_NAME,
 113
 114         .reg_bits = 8,
 115         .val_bits = 8,
 116
 117         .readable_reg = mxc6255_is_readable_reg,
 118 };
 119
 120 static int mxc6255_probe(struct i2c_client *client,
 121                          const struct i2c_device_id *id)
 122 {
 123         struct mxc6255_data *data;
 124         struct iio_dev *indio_dev;
 125         struct regmap *regmap;
 126         unsigned int chip_id;
 127         int ret;
 128
 129         indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
 130         if (!indio_dev)
 131                 return -ENOMEM;
 132
 133         regmap = devm_regmap_init_i2c(client, &mxc6255_regmap_config);
 134         if (IS_ERR(regmap)) {
 135                 dev_err(&client->dev, "Error initializing regmap\n");
 136                 return PTR_ERR(regmap);
 137         }
 138
 139         data = iio_priv(indio_dev);
 140         i2c_set_clientdata(client, indio_dev);
 141         data->client = client;
 142         data->regmap = regmap;
 143
 144         indio_dev->name = MXC6255_DRV_NAME;
 145         indio_dev->dev.parent = &client->dev;
 146         indio_dev->channels = mxc6255_channels;
 147         indio_dev->num_channels = ARRAY_SIZE(mxc6255_channels);
 148         indio_dev->modes = INDIO_DIRECT_MODE;
 149         indio_dev->info = &mxc6255_info;
 150
 151         ret = regmap_read(data->regmap, MXC6255_REG_CHIP_ID, &chip_id);
 152         if (ret < 0) {
 153                 dev_err(&client->dev, "Error reading chip id %d\n", ret);
 154                 return ret;
 155         }
 156
 157         if (chip_id != MXC6255_CHIP_ID) {
 158                 dev_err(&client->dev, "Invalid chip id %x\n", chip_id);
 159                 return -ENODEV;
 160         }
 161
 162         dev_dbg(&client->dev, "Chip id %x\n", chip_id);
 163
 164         ret = devm_iio_device_register(&client->dev, indio_dev);
 165         if (ret < 0) {
 166                 dev_err(&client->dev, "Could not register IIO device\n");
 167                 return ret;
 168         }
 169
 170         return 0;
 171 }
 172
 173 static const struct acpi_device_id mxc6255_acpi_match[] = {
 174         {"MXC6255",     0},
 175         { }
 176 };
 177 MODULE_DEVICE_TABLE(acpi, mxc6255_acpi_match);
 178
 179 static const struct i2c_device_id mxc6255_id[] = {
 180         {"mxc6255",     0},
 181         { }
 182 };
 183 MODULE_DEVICE_TABLE(i2c, mxc6255_id);
 184
 185 static struct i2c_driver mxc6255_driver = {
 186         .driver = {
 187                 .name = MXC6255_DRV_NAME,
 188                 .acpi_match_table = ACPI_PTR(mxc6255_acpi_match),
 189         },
 190         .probe          = mxc6255_probe,
 191         .id_table       = mxc6255_id,
 192 };
 193
 194 module_i2c_driver(mxc6255_driver);
 195
 196 MODULE_AUTHOR("Teodora Baluta <teodora.baluta@intel.com>");
 197 MODULE_DESCRIPTION("MEMSIC MXC6255 orientation sensing accelerometer driver");
 198 MODULE_LICENSE("GPL v2");