On Wed, Jan 25, 2017 at 10:37:33AM +0100, Peter Meerwald-Stadler wrote:

quoted

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

comments below
 

Hello Peter,

Thanks for the review.

quoted

Signed-off-by: Eva Rachel Retuya <redacted>
Cc: Michael Hennerich <michael.hennerich@analog.com>
Cc: Daniel Baluta <redacted>
Cc: Alison Schofield <redacted>
---
Note that this sensor is already supported in input/misc/adxl34x. This IIO
driver only supports read_raw on x, y and z axes in full-resolution mode.

 drivers/iio/accel/Kconfig   |  10 +++
 drivers/iio/accel/Makefile  |   1 +
 drivers/iio/accel/adxl345.c | 173 ++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 184 insertions(+)
 create mode 100644 drivers/iio/accel/adxl345.c

diff --git a/drivers/iio/accel/Kconfig b/drivers/iio/accel/Kconfig
index ea295fe..b73f403 100644
--- a/drivers/iio/accel/Kconfig
+++ b/drivers/iio/accel/Kconfig

@@ -5,6 +5,16 @@
 
 menu "Accelerometers"
 
+config ADXL345
+	tristate "Analog Devices ADXL345 3-Axis Digital Accelerometer Driver"
+	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..54ea601
--- /dev/null
+++ b/drivers/iio/accel/adxl345.c

@@ -0,0 +1,173 @@
+/*
+ * 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)

buffered mode would be useful in order to get consistent measurements of 
all three axis at once

Noted. I'm waiting for feedback from others to see whether I can extend
this driver further.

quoted

+ */
+
+#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)

maybe state in comment that FULL_RES is 12 bit

Ack.

quoted

+#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
+
+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),			\

haven't checked but likely we need _SCALE to present the correct unit of 
measurement

I was told to send just the raw measurement only however, I have a patch ready
with the scale in mind.

quoted

+}
+
+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
+		 */

there is no data ready? we might get old data?

This is just a simple IIO driver so yes, not yet implemented.

quoted

+		ret = i2c_smbus_read_word_data(data->client, chan->address);
+

drop newline

Ack.

quoted

+		if (ret < 0)
+			return ret;
+
+		*val = sign_extend32(le16_to_cpu(ret), 12);

le16_to_cpu() not needed, I2C read_word_data does it for you

Ack.

quoted

+		return IIO_VAL_INT;
+	}
+
+	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;
+	}
+
+	return iio_device_register(indio_dev);

stop measurement mode if registration fails

Ack.

Best Regards,
Eva

quoted

+}
+
+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 [off-list ref]");
+MODULE_DESCRIPTION("ADXL345 3-Axis Digital Accelerometer driver");
+MODULE_LICENSE("GPL v2");

-- 

Peter Meerwald-Stadler
+43-664-2444418 (mobile)