iio: core: Introduce IIO_ACTIVITY channel

This channel will be used for exposing information about
activity composite sensors. Activities supported so far:
	* running
	* jogging
	* walking
	* still

THRESHOLD event is used to signal a change in the activity
state.

We associate a confidence interval for each activity expressed
as a percentage from 0 to 100.
  * 0, means the sensor IS NOT reporting that activity.
  * 100, means the sensor IS reporting that activity.

Users of this interface have two possible means to gather
information about the ongoing activities.

1. Event based, via event file descriptor
  * sensor may report an event when ENTERING an activity or LEAVING
    an activity based on a threshold value.
  * drivers will wake up applications waiting data on the event fd

2. Polling, by reading the sysfs associated attribute files:
  * /sys/bus/iio/devices/iio:device0/in_activity_running_input
expressed as percentage confidence value from 0 to 100.

This will offer an interface for Android significant motion
composite sensor defined here:
http://source.android.com/devices/sensors/composite_sensors.html

Activities listed above are supported by Freescale's MMA9553 sensor:
http://freescale.com/files/sensors/doc/ref_manual/MMA9553LSWRM.pdf

Signed-off-by: Irina Tirdea <irina.tirdea@intel.com>
Signed-off-by: Daniel Baluta <daniel.baluta@intel.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

3 files changed, 55 insertions, 1 deletions

diff --git a/Documentation/ABI/testing/sysfs-bus-iio b/Documentation/ABI/testing/sysfs-bus-iio
index 117521dbf2b3..7bf49ad8fd82 100644
--- a/Documentation/ABI/testing/sysfs-bus-iio
+++ b/Documentation/ABI/testing/sysfs-bus-iio
@@ -790,6 +790,40 @@ Description:
                 met before an event is generated. If direction is not
                 specified then this period applies to both directions.
 
+What:           /sys/.../events/in_activity_still_thresh_rising_en
+What:           /sys/.../events/in_activity_still_thresh_falling_en
+What:           /sys/.../events/in_activity_walking_thresh_rising_en
+What:           /sys/.../events/in_activity_walking_thresh_falling_en
+What:           /sys/.../events/in_activity_jogging_thresh_rising_en
+What:           /sys/.../events/in_activity_jogging_thresh_falling_en
+What:           /sys/.../events/in_activity_running_thresh_rising_en
+What:           /sys/.../events/in_activity_running_thresh_falling_en
+KernelVersion:  3.19
+Contact:        linux-iio@vger.kernel.org
+Description:
+                Enables or disables activitity events. Depending on direction
+                an event is generated when sensor ENTERS or LEAVES a given state.
+
+What:           /sys/.../events/in_activity_still_thresh_rising_value
+What:           /sys/.../events/in_activity_still_thresh_falling_value
+What:           /sys/.../events/in_activity_walking_thresh_rising_value
+What:           /sys/.../events/in_activity_walking_thresh_falling_value
+What:           /sys/.../events/in_activity_jogging_thresh_rising_value
+What:           /sys/.../events/in_activity_jogging_thresh_falling_value
+What:           /sys/.../events/in_activity_running_thresh_rising_value
+What:           /sys/.../events/in_activity_running_thresh_falling_value
+KernelVersion:  3.19
+Contact:        linux-iio@vger.kernel.org
+Description:
+                Confidence value (in units as percentage) to be used
+                for deciding when an event should be generated. E.g for
+                running: If the confidence value reported by the sensor
+                is greater than in_activity_running_thresh_rising_value
+                then the sensor ENTERS running state. Conversely, if the
+                confidence value reported by the sensor is lower than
+                in_activity_running_thresh_falling_value then the sensor
+                is LEAVING running state.
+
 What:           /sys/.../iio:deviceX/events/in_accel_mag_en
 What:           /sys/.../iio:deviceX/events/in_accel_mag_rising_en
 What:           /sys/.../iio:deviceX/events/in_accel_mag_falling_en
@@ -956,6 +990,16 @@ Description:
                 and the relevant _type attributes to establish the data storage
                 format.
 
+What:           /sys/.../iio:deviceX/in_activity_still_input
+What:           /sys/.../iio:deviceX/in_activity_walking_input
+What:           /sys/.../iio:deviceX/in_activity_jogging_input
+What:           /sys/.../iio:deviceX/in_activity_running_input
+KernelVersion:  3.19
+Contact:        linux-iio@vger.kernel.org
+Description:
+                This attribute is used to read the confidence for an activity
+                expressed in units as percentage.
+
 What:           /sys/.../iio:deviceX/in_anglvel_z_quadrature_correction_raw
 KernelVersion:  2.6.38
 Contact:        linux-iio@vger.kernel.org
diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c
index af3e76d652ba..e453ef9e0c36 100644
--- a/drivers/iio/industrialio-core.c
+++ b/drivers/iio/industrialio-core.c
@@ -70,6 +70,7 @@ static const char * const iio_chan_type_name_spec[] = {
         [IIO_CCT] = "cct",
         [IIO_PRESSURE] = "pressure",
         [IIO_HUMIDITYRELATIVE] = "humidityrelative",
+        [IIO_ACTIVITY] = "activity",
 };
 
 static const char * const iio_modifier_names[] = {
@@ -91,6 +92,10 @@ static const char * const iio_modifier_names[] = {
         [IIO_MOD_NORTH_TRUE] = "from_north_true",
         [IIO_MOD_NORTH_MAGN_TILT_COMP] = "from_north_magnetic_tilt_comp",
         [IIO_MOD_NORTH_TRUE_TILT_COMP] = "from_north_true_tilt_comp",
+        [IIO_MOD_RUNNING] = "running",
+        [IIO_MOD_JOGGING] = "jogging",
+        [IIO_MOD_WALKING] = "walking",
+        [IIO_MOD_STILL] = "still",
 };
 
 /* relies on pairs of these shared then separate */
diff --git a/include/linux/iio/types.h b/include/linux/iio/types.h
index 4a2af8adf874..b3a241d53b54 100644
--- a/include/linux/iio/types.h
+++ b/include/linux/iio/types.h
@@ -30,6 +30,7 @@ enum iio_chan_type {
         IIO_CCT,
         IIO_PRESSURE,
         IIO_HUMIDITYRELATIVE,
+        IIO_ACTIVITY,
 };
 
 enum iio_modifier {
@@ -59,7 +60,11 @@ enum iio_modifier {
         IIO_MOD_NORTH_MAGN,
         IIO_MOD_NORTH_TRUE,
         IIO_MOD_NORTH_MAGN_TILT_COMP,
-        IIO_MOD_NORTH_TRUE_TILT_COMP
+        IIO_MOD_NORTH_TRUE_TILT_COMP,
+        IIO_MOD_RUNNING,
+        IIO_MOD_JOGGING,
+        IIO_MOD_WALKING,
+        IIO_MOD_STILL,
 };
 
 enum iio_event_type {