Re: [PATCH v2] iio: accel: Add driver for the Analog Devices ADXL345 3-axis accelerometer

[Jonathan Cameron <jic23@kernel.org>]

On 05/02/17 08:20, Eva Rachel Retuya wrote:
> On Sat, Feb 04, 2017 at 12:34:57PM +0000, Jonathan Cameron wrote:
>> On 31/01/17 07:12, Eva Rachel Retuya wrote:
>>> 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>
>> Looks good to me.
>>
>> So my only question is about how you would like to handle this.
>> Clearly you are actively working on the driver so would you prefer:
>>
>> 1) I take each step into the iio tree as and when it is ready (I think this one is)
> Hello Jonathan,
> 
> I'll go with this option. Add the initial support then submit patches
> for the other features.
Applied to the togreg branch of iio.git and pushed out as testing for the autobuilders
to play with it.

Thanks,

Jonathan
> 
> Thanks,
> Eva
>> 2) We build up a full series of patches taking this driver all the way and then I take
>> that whole set at once.
>>
>> I'm happy either way, it just depends on what works best for you.
>>
>> Note that practically we've just missed the 4.11 merge window so have 3 months
>> until the next one.  In the meantime we can get stuff all ready to go and into 
>> linux-next etc.
>>
>> Jonathan
>>> ---
>>> 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");
>>>
>>
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