[PATCH v2 07/10] iio: core: Introduce IIO_CHAN_INFO_FILTER_OUTLIERS_THRESH and _PERIOD

[Irina Tirdea <irina.tirdea@intel.com>]

The pedometer needs to filter out false steps that might be generated by
tapping the foot, sitting, etc. To do that it computes the number of
steps that occur in a given time and decides the user is moving only
if this value is over a threshold. E.g.: the user starts moving only
if he takes 4 steps in 3 seconds. This filter is applied only when
the user starts moving.

A device that has such pedometer functionality is Freescale's MMA9553L:
http://www.freescale.com/files/sensors/doc/ref_manual/MMA9553LSWRM.pdf.

To export this feature, this patch introduces
IIO_CHAN_INFO_FILTER_OUTLIERS_THRESH and IIO_CHAN_INFO_FILTER_OUTLIERS_PERIOD.
For the pedometer, in_steps_filter_outlier_thresh will specify the number of
steps that need to occur in in_steps_filter_outlier_period seconds so that
the pedometer decides the user is moving.

Signed-off-by: Irina Tirdea <irina.tirdea@intel.com>
---
 Documentation/ABI/testing/sysfs-bus-iio | 21 +++++++++++++++++++++
 drivers/iio/industrialio-core.c         |  2 ++
 include/linux/iio/iio.h                 |  2 ++
 3 files changed, 25 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-bus-iio b/Documentation/ABI/testing/sysfs-bus-iio
index c03a140..e009f49 100644
--- a/Documentation/ABI/testing/sysfs-bus-iio
+++ b/Documentation/ABI/testing/sysfs-bus-iio
@@ -1193,3 +1193,24 @@ Description:
 		This attribute is used to read the current speed value of the
 		user (which is the norm or magnitude of the velocity vector).
 		Units after application of scale are m/s.
+
+What:		/sys/.../iio:deviceX/in_steps_filter_outliers_period
+KernelVersion:	3.20
+Contact:	linux-iio@vger.kernel.org
+Description:
+		Specifies the number of seconds in which we compute the
+		values so we can decide if they are outlier values and
+		need to be filter out. These computed values are then
+		compared with in_steps_filter_outliers_thresh. E.g. for steps:
+		specifies number of seconds in which we compute the steps
+		that occur in order to decide if the consumer is making steps.
+
+What:		/sys/.../iio:deviceX/in_steps_filter_outliers_thresh
+KernelVersion:	3.20
+Contact:	linux-iio@vger.kernel.org
+Description:
+		Specifies a threshold for filtering outlier values: if value
+		measured in in_steps_filter_outliers_period seconds is below
+		threshold, we filter it out. E.g. for steps: specifies number
+		of steps that must occur within in_steps_filter_outliers_period
+		for the pedometer to decide the consumer is making steps.
diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c
index 4ee6fdf..81678b3 100644
--- a/drivers/iio/industrialio-core.c
+++ b/drivers/iio/industrialio-core.c
@@ -126,6 +126,8 @@ static const char * const iio_chan_info_postfix[] = {
 	[IIO_CHAN_INFO_ENABLE] = "en",
 	[IIO_CHAN_INFO_CALIBHEIGHT] = "calibheight",
 	[IIO_CHAN_INFO_CALIBWEIGHT] = "calibweight",
+	[IIO_CHAN_INFO_FILTER_OUTLIERS_THRESH] = "filter_outliers_thresh",
+	[IIO_CHAN_INFO_FILTER_OUTLIERS_PERIOD] = "filter_outliers_period",
 };
 
 /**
diff --git a/include/linux/iio/iio.h b/include/linux/iio/iio.h
index 752a929..b6b12ac 100644
--- a/include/linux/iio/iio.h
+++ b/include/linux/iio/iio.h
@@ -41,6 +41,8 @@ enum iio_chan_info_enum {
 	IIO_CHAN_INFO_ENABLE,
 	IIO_CHAN_INFO_CALIBHEIGHT,
 	IIO_CHAN_INFO_CALIBWEIGHT,
+	IIO_CHAN_INFO_FILTER_OUTLIERS_THRESH,
+	IIO_CHAN_INFO_FILTER_OUTLIERS_PERIOD,
 };
 
 enum iio_shared_by {
-- 
1.9.1