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    Subject[PATCH v2] iio: accel: Add driver for the Analog Devices ADXL345 3-axis accelerometer
    Date
    Add basic IIO support for the Analog Devices ADXL345 3-axis accelerometer.
    The datasheet can be found here:
    http://www.analog.com/media/en/technical-documentation/data-sheets/ADXL345.pdf

    Signed-off-by: Eva Rachel Retuya <eraretuya@gmail.com>
    Cc: Michael Hennerich <michael.hennerich@analog.com>
    Cc: Daniel Baluta <daniel.baluta@gmail.com>
    Cc: Alison Schofield <amsfield22@gmail.com>
    ---
    v1 Mailing list discussion:
    https://marc.info/?l=linux-iio&m=148533644407371&w=2

    Changes since v1:
    * Switch tag from RFC to PATCH
    From Jonathan's Review
    * Kconfig: add input driver's (adxl34x) selection state as dependency.
    From Peter's Review
    * Implement full-resolution mode scale.
    * Add comment stating FULL_RES is up to 13-bits in resolution.
    * Drop newline and le16_to_cpu usage in read_raw.
    * Allow the sensor to return to standby mode if iio_device_register fails.

    drivers/iio/accel/Kconfig | 11 +++
    drivers/iio/accel/Makefile | 1 +
    drivers/iio/accel/adxl345.c | 194 ++++++++++++++++++++++++++++++++++++++++++++
    3 files changed, 206 insertions(+)
    create mode 100644 drivers/iio/accel/adxl345.c

    diff --git a/drivers/iio/accel/Kconfig b/drivers/iio/accel/Kconfig
    index ef8401a..2308bac 100644
    --- a/drivers/iio/accel/Kconfig
    +++ b/drivers/iio/accel/Kconfig
    @@ -5,6 +5,17 @@

    menu "Accelerometers"

    +config ADXL345
    + tristate "Analog Devices ADXL345 3-Axis Digital Accelerometer Driver"
    + depends on !(INPUT_ADXL34X=y || INPUT_ADXL34X=m)
    + depends on I2C
    + help
    + Say Y here if you want to build support for the Analog Devices
    + ADXL345 3-axis digital accelerometer.
    +
    + To compile this driver as a module, choose M here: the
    + module will be called adxl345.
    +
    config BMA180
    tristate "Bosch BMA180/BMA250 3-Axis Accelerometer Driver"
    depends on I2C
    diff --git a/drivers/iio/accel/Makefile b/drivers/iio/accel/Makefile
    index 69fe8ed..618488d 100644
    --- a/drivers/iio/accel/Makefile
    +++ b/drivers/iio/accel/Makefile
    @@ -3,6 +3,7 @@
    #

    # When adding new entries keep the list in alphabetical order
    +obj-$(CONFIG_ADXL345) += adxl345.o
    obj-$(CONFIG_BMA180) += bma180.o
    obj-$(CONFIG_BMA220) += bma220_spi.o
    obj-$(CONFIG_BMC150_ACCEL) += bmc150-accel-core.o
    diff --git a/drivers/iio/accel/adxl345.c b/drivers/iio/accel/adxl345.c
    new file mode 100644
    index 0000000..c34991f
    --- /dev/null
    +++ b/drivers/iio/accel/adxl345.c
    @@ -0,0 +1,194 @@
    +/*
    + * ADXL345 3-Axis Digital Accelerometer
    + *
    + * Copyright (c) 2017 Eva Rachel Retuya <eraretuya@gmail.com>
    + *
    + * This file is subject to the terms and conditions of version 2 of
    + * the GNU General Public License. See the file COPYING in the main
    + * directory of this archive for more details.
    + *
    + * IIO driver for ADXL345
    + * 7-bit I2C slave address: 0x1D (ALT ADDRESS pin tied to VDDIO) or
    + * 0x53 (ALT ADDRESS pin grounded)
    + */
    +
    +#include <linux/i2c.h>
    +#include <linux/module.h>
    +
    +#include <linux/iio/iio.h>
    +
    +#define ADXL345_REG_DEVID 0x00
    +#define ADXL345_REG_POWER_CTL 0x2D
    +#define ADXL345_REG_DATA_FORMAT 0x31
    +#define ADXL345_REG_DATAX0 0x32
    +#define ADXL345_REG_DATAY0 0x34
    +#define ADXL345_REG_DATAZ0 0x36
    +
    +#define ADXL345_POWER_CTL_MEASURE BIT(3)
    +#define ADXL345_POWER_CTL_STANDBY 0x00
    +
    +#define ADXL345_DATA_FORMAT_FULL_RES BIT(3) /* Up to 13-bits resolution */
    +#define ADXL345_DATA_FORMAT_2G 0
    +#define ADXL345_DATA_FORMAT_4G 1
    +#define ADXL345_DATA_FORMAT_8G 2
    +#define ADXL345_DATA_FORMAT_16G 3
    +
    +#define ADXL345_DEVID 0xE5
    +
    +/*
    + * In full-resolution mode, scale factor is maintained at ~4 mg/LSB
    + * in all g ranges.
    + *
    + * At +/- 16g with 13-bit resolution, scale is computed as:
    + * (16 + 16) * 9.81 / (2^13 - 1) = 0.0383
    + */
    +static const int adxl345_uscale = 38300;
    +
    +struct adxl345_data {
    + struct i2c_client *client;
    + u8 data_range;
    +};
    +
    +#define ADXL345_CHANNEL(reg, axis) { \
    + .type = IIO_ACCEL, \
    + .modified = 1, \
    + .channel2 = IIO_MOD_##axis, \
    + .address = reg, \
    + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
    + .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
    +}
    +
    +static const struct iio_chan_spec adxl345_channels[] = {
    + ADXL345_CHANNEL(ADXL345_REG_DATAX0, X),
    + ADXL345_CHANNEL(ADXL345_REG_DATAY0, Y),
    + ADXL345_CHANNEL(ADXL345_REG_DATAZ0, Z),
    +};
    +
    +static int adxl345_read_raw(struct iio_dev *indio_dev,
    + struct iio_chan_spec const *chan,
    + int *val, int *val2, long mask)
    +{
    + struct adxl345_data *data = iio_priv(indio_dev);
    + int ret;
    +
    + switch (mask) {
    + case IIO_CHAN_INFO_RAW:
    + /*
    + * Data is stored in adjacent registers:
    + * ADXL345_REG_DATA(X0/Y0/Z0) contain the least significant byte
    + * and ADXL345_REG_DATA(X0/Y0/Z0) + 1 the most significant byte
    + */
    + ret = i2c_smbus_read_word_data(data->client, chan->address);
    + if (ret < 0)
    + return ret;
    +
    + *val = sign_extend32(ret, 12);
    + return IIO_VAL_INT;
    + case IIO_CHAN_INFO_SCALE:
    + *val = 0;
    + *val2 = adxl345_uscale;
    +
    + return IIO_VAL_INT_PLUS_MICRO;
    + }
    +
    + return -EINVAL;
    +}
    +
    +static const struct iio_info adxl345_info = {
    + .driver_module = THIS_MODULE,
    + .read_raw = adxl345_read_raw,
    +};
    +
    +static int adxl345_probe(struct i2c_client *client,
    + const struct i2c_device_id *id)
    +{
    + struct adxl345_data *data;
    + struct iio_dev *indio_dev;
    + int ret;
    +
    + ret = i2c_smbus_read_byte_data(client, ADXL345_REG_DEVID);
    + if (ret < 0) {
    + dev_err(&client->dev, "Error reading device ID: %d\n", ret);
    + return ret;
    + }
    +
    + if (ret != ADXL345_DEVID) {
    + dev_err(&client->dev, "Invalid device ID: %d\n", ret);
    + return -ENODEV;
    + }
    +
    + indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
    + if (!indio_dev)
    + return -ENOMEM;
    +
    + data = iio_priv(indio_dev);
    + i2c_set_clientdata(client, indio_dev);
    + data->client = client;
    + /* Enable full-resolution mode */
    + data->data_range = ADXL345_DATA_FORMAT_FULL_RES;
    +
    + ret = i2c_smbus_write_byte_data(data->client, ADXL345_REG_DATA_FORMAT,
    + data->data_range);
    + if (ret < 0) {
    + dev_err(&client->dev, "Failed to set data range: %d\n", ret);
    + return ret;
    + }
    +
    + indio_dev->dev.parent = &client->dev;
    + indio_dev->name = id->name;
    + indio_dev->info = &adxl345_info;
    + indio_dev->modes = INDIO_DIRECT_MODE;
    + indio_dev->channels = adxl345_channels;
    + indio_dev->num_channels = ARRAY_SIZE(adxl345_channels);
    +
    + /* Enable measurement mode */
    + ret = i2c_smbus_write_byte_data(data->client, ADXL345_REG_POWER_CTL,
    + ADXL345_POWER_CTL_MEASURE);
    + if (ret < 0) {
    + dev_err(&client->dev, "Failed to enable measurement mode: %d\n",
    + ret);
    + return ret;
    + }
    +
    + ret = iio_device_register(indio_dev);
    + if (ret < 0) {
    + dev_err(&client->dev, "iio_device_register failed: %d\n", ret);
    + i2c_smbus_write_byte_data(data->client, ADXL345_REG_POWER_CTL,
    + ADXL345_POWER_CTL_STANDBY);
    + }
    +
    + return ret;
    +}
    +
    +static int adxl345_remove(struct i2c_client *client)
    +{
    + struct iio_dev *indio_dev = i2c_get_clientdata(client);
    + struct adxl345_data *data = iio_priv(indio_dev);
    +
    + iio_device_unregister(indio_dev);
    +
    + return i2c_smbus_write_byte_data(data->client, ADXL345_REG_POWER_CTL,
    + ADXL345_POWER_CTL_STANDBY);
    +}
    +
    +static const struct i2c_device_id adxl345_i2c_id[] = {
    + { "adxl345", 0 },
    + { }
    +};
    +
    +MODULE_DEVICE_TABLE(i2c, adxl345_i2c_id);
    +
    +static struct i2c_driver adxl345_driver = {
    + .driver = {
    + .name = "adxl345",
    + },
    + .probe = adxl345_probe,
    + .remove = adxl345_remove,
    + .id_table = adxl345_i2c_id,
    +};
    +
    +module_i2c_driver(adxl345_driver);
    +
    +MODULE_AUTHOR("Eva Rachel Retuya <eraretuya@gmail.com>");
    +MODULE_DESCRIPTION("ADXL345 3-Axis Digital Accelerometer driver");
    +MODULE_LICENSE("GPL v2");
    --
    2.7.4
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      Last update: 2017-01-31 08:27    [W:4.941 / U:0.004 seconds]
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