linux-kernel - Re: [RFC PATCH 3/8] iio: core: Introduce new MOTION event

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Date:	Sat, 04 Oct 2014 14:12:50 +0100
From:	Jonathan Cameron <jic23@...nel.org>
To:	Daniel Baluta <daniel.baluta@...el.com>, linux-iio@...r.kernel.org,
	linux-kernel@...r.kernel.org
CC:	irina.tirdea@...el.com
Subject: Re: [RFC PATCH 3/8] iio: core: Introduce new MOTION event

On 02/10/14 14:43, Daniel Baluta wrote:
> This is to be used by drivers to signal detection of motion. We also
> add some possible values for motion as IIO events modifiers:
> 	* running
> 	* jogging
> 	* walking
> 	* still
> 
> These values are supported by Frescale's MMA9553 sensor:
> 
> http://freescale.com/files/sensors/doc/ref_manual/MMA9553LSWRM.pdf
> 
> Signed-off-by: Daniel Baluta <daniel.baluta@...el.com>
> Signed-off-by: Irina Tirdea <irina.tirdea@...el.com>
Hmm.. This is the interesting one.
Not immediately obvious how best to represent this stuff.
> ---
>  Documentation/ABI/testing/sysfs-bus-iio | 7 +++++++
>  drivers/iio/industrialio-core.c         | 4 ++++
>  drivers/iio/industrialio-event.c        | 1 +
>  include/linux/iio/types.h               | 7 ++++++-
>  4 files changed, 18 insertions(+), 1 deletion(-)
> 
> diff --git a/Documentation/ABI/testing/sysfs-bus-iio b/Documentation/ABI/testing/sysfs-bus-iio
> index d760b02..070346d 100644
> --- a/Documentation/ABI/testing/sysfs-bus-iio
> +++ b/Documentation/ABI/testing/sysfs-bus-iio
> @@ -808,6 +808,13 @@ Description:
>  		number or direction is not specified, applies to all channels of
>  		this type.
>  
> +What:		/sys/.../events/in_activity_motion_either_en
> +KernelVersion:	3.17
> +Contact:	linux-iio@...r.kernel.org
> +Description:
> +		Enables or disables motion detection. Each time motion is detected an
> +		event of this type will be generated.
> +
The either bit seems a bit random but I can see there is no particularly obvious
alternative.

We really need a clean way of representing a multilevel 'state change' like this.

Looking at the event code, I almost wonder if we would be better using the
direction element for running, walking etc rather than a modifier.

Having said that we will probably also get devices where this is polled rather than
event.  'What activity is currently going on?'
If we take that view modifiers make sense as it becomes
'Is the user running?'  Perhaps even offering a confidence interval, e.g units as
percentage
in_activity_running_input 0..100
in_activity_walking_input 0..100
etc

Then our event becomes a state change event (yup we'll need to add that)

/events/in_activity_walking_rising_en  will then cause events when the percentage
confidence on a state rises above the provided threshold or goes above it
(default of 50% perhaps on devices which only report one state).

/events/in_activity_walking_falling_en will do the leaving case.

Note these are just some quick initial thoughts on alternative methods.
I'll want to think on this more and get responses from more interested
parties!

>  What:		/sys/bus/iio/devices/iio:deviceX/trigger/current_trigger
>  KernelVersion:	2.6.35
>  Contact:	linux-iio@...r.kernel.org
> diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c
> index 67e8561..e453ef9 100644
> --- a/drivers/iio/industrialio-core.c
> +++ b/drivers/iio/industrialio-core.c
> @@ -92,6 +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/drivers/iio/industrialio-event.c b/drivers/iio/industrialio-event.c
> index 0c1e37e..eca5af2 100644
> --- a/drivers/iio/industrialio-event.c
> +++ b/drivers/iio/industrialio-event.c
> @@ -197,6 +197,7 @@ static const char * const iio_ev_type_text[] = {
>  	[IIO_EV_TYPE_ROC] = "roc",
>  	[IIO_EV_TYPE_THRESH_ADAPTIVE] = "thresh_adaptive",
>  	[IIO_EV_TYPE_MAG_ADAPTIVE] = "mag_adaptive",
> +	[IIO_EV_TYPE_MOTION] = "motion",
>  };
>  
>  static const char * const iio_ev_dir_text[] = {
> diff --git a/include/linux/iio/types.h b/include/linux/iio/types.h
> index d58769a..003638d 100644
> --- a/include/linux/iio/types.h
> +++ b/include/linux/iio/types.h
> @@ -60,7 +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 {
> @@ -69,6 +73,7 @@ enum iio_event_type {
>  	IIO_EV_TYPE_ROC,
>  	IIO_EV_TYPE_THRESH_ADAPTIVE,
>  	IIO_EV_TYPE_MAG_ADAPTIVE,
> +	IIO_EV_TYPE_MOTION,
>  };
>  
>  enum iio_event_info {
> 
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