Re: [RFC PATCH v2 4/7] iio: core: Introduce STEPS channel type, ENABLE mask and INSTANCE event

[Jonathan Cameron]

On 09/10/14 13:39, Daniel Baluta wrote:
> From: Irina Tirdea <irina.tirdea@xxxxxxxxx>
> 
> These changes are needed to support the functionality of a pedometer.
> A pedometer has two basic functionalities: step counter and step detector.
> 
> The step counter needs to be enabled and then it will count the steps
> in its hardware register. Whenever the application needs to check
> the step count, it will read the step counter register. To support the
> step counter a new channel type STEPS is added. Since the pedometer needs
> to be enabled first so that the hardware can count and store the steps,

> we need a specific ENABLE channel info mask.
Perhaps enable and zero?  (thus a second hit on it would reset the counter?)
Actually you have to wonder why these don't free run and just let userspace
do the subtraction.  Would make things slightly simpler all round.
Chances are we'll soon get a device that does exactly that but then I suppose
that just doesn't supply an 'enable' attribute.

> 
> The step detector will generate an interrupt each time a step is detected.
> To support this functionality we add a new event type INSTANCE.
Hmm.  Other option on this would be to use it as a trigger and do buffered output
of the steps counter.   However, I think the approach you have is preferable.

I wonder if instance is the best name.   Not that I've come up with a better
one.  Btw, drop the RFC probably at this point as I suspect it means some
of my keen reviewers aren't reading the patches yet ;) I think you are rapidly
progressing beyond the RFC stage anyway!
> 
> For more information on the Android requirements for step counter and step
> detector see:
> http://source.android.com/devices/sensors/composite_sensors.html#counter
> and http://source.android.com/devices/sensors/composite_sensors.html#detector.
> 
> A device that has the pedometer functionality this interface needs to
> support is Freescale's MMA9553L:
> http://www.freescale.com/files/sensors/doc/ref_manual/MMA9553LSWRM.pdf
> 
> Signed-off-by: Irina Tirdea <irina.tirdea@xxxxxxxxx>
> Signed-off-by: Daniel Baluta <daniel.baluta@xxxxxxxxx>
> ---
>  Documentation/ABI/testing/sysfs-bus-iio | 22 ++++++++++++++++++++++
>  drivers/iio/industrialio-core.c         |  2 ++
>  drivers/iio/industrialio-event.c        |  1 +
>  include/linux/iio/iio.h                 |  1 +
>  include/linux/iio/types.h               |  2 ++
>  5 files changed, 28 insertions(+)
> 
> diff --git a/Documentation/ABI/testing/sysfs-bus-iio b/Documentation/ABI/testing/sysfs-bus-iio
> index 12d0385..3557a69 100644
> --- a/Documentation/ABI/testing/sysfs-bus-iio
> +++ b/Documentation/ABI/testing/sysfs-bus-iio
> @@ -842,6 +842,13 @@ Description:
>  		number or direction is not specified, applies to all channels of
>  		this type.
>  
> +What:		/sys/.../events/in_steps_instance_en
> +KernelVersion:	3.19
> +Contact:	linux-iio@xxxxxxxxxxxxxxx
> +Description:
> +		Enables or disables step detection. Each time the user takes a step an
> +		event of this type will be generated.
> +
>  What:		/sys/bus/iio/devices/iio:deviceX/trigger/current_trigger
>  KernelVersion:	2.6.35
>  Contact:	linux-iio@xxxxxxxxxxxxxxx
> @@ -1072,3 +1079,18 @@ Contact:	linux-iio@xxxxxxxxxxxxxxx
>  Description:
>  		Raw value of rotation from true/magnetic north measured with
>  		or without compensation from tilt sensors.
> +
> +What:		/sys/.../iio:deviceX/in_steps_enable
> +KernelVersion:	3.19
> +Contact:	linux-iio@xxxxxxxxxxxxxxx
> +Description:
> +		Activates the step counter. After activation, the number of steps
> +		taken by the user will be counted in hardware and exported through
> +		in_steps_input.
> +
> +What:		/sys/.../iio:deviceX/in_steps_input
> +KernelVersion:	3.19
> +Contact:	linux-iio@xxxxxxxxxxxxxxx
> +Description:
> +		This attribute is used to read the number of steps taken by the user
> +		since the last reboot while activated.
> diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c
> index e453ef9..1e060f3 100644
> --- a/drivers/iio/industrialio-core.c
> +++ b/drivers/iio/industrialio-core.c
> @@ -71,6 +71,7 @@ static const char * const iio_chan_type_name_spec[] = {
>  	[IIO_PRESSURE] = "pressure",
>  	[IIO_HUMIDITYRELATIVE] = "humidityrelative",
>  	[IIO_ACTIVITY] = "activity",
> +	[IIO_STEPS] = "steps",
>  };
>  
>  static const char * const iio_modifier_names[] = {
> @@ -118,6 +119,7 @@ static const char * const iio_chan_info_postfix[] = {
>  	[IIO_CHAN_INFO_HARDWAREGAIN] = "hardwaregain",
>  	[IIO_CHAN_INFO_HYSTERESIS] = "hysteresis",
>  	[IIO_CHAN_INFO_INT_TIME] = "integration_time",
> +	[IIO_CHAN_INFO_ENABLE] = "en",
you have en here and enable in the docs.
>  };
>  
>  /**
> diff --git a/drivers/iio/industrialio-event.c b/drivers/iio/industrialio-event.c
> index a9c9f34..db63d29 100644
> --- a/drivers/iio/industrialio-event.c
> +++ b/drivers/iio/industrialio-event.c
> @@ -198,6 +198,7 @@ static const char * const iio_ev_type_text[] = {
>  	[IIO_EV_TYPE_THRESH_ADAPTIVE] = "thresh_adaptive",
>  	[IIO_EV_TYPE_MAG_ADAPTIVE] = "mag_adaptive",
>  	[IIO_EV_TYPE_TRANSITION] = "transition",
> +	[IIO_EV_TYPE_INSTANCE] = "instance",
>  };
>  
>  static const char * const iio_ev_dir_text[] = {
> diff --git a/include/linux/iio/iio.h b/include/linux/iio/iio.h
> index 15dc6bc..3d3f06f 100644
> --- a/include/linux/iio/iio.h
> +++ b/include/linux/iio/iio.h
> @@ -37,6 +37,7 @@ enum iio_chan_info_enum {
>  	IIO_CHAN_INFO_HARDWAREGAIN,
>  	IIO_CHAN_INFO_HYSTERESIS,
>  	IIO_CHAN_INFO_INT_TIME,
> +	IIO_CHAN_INFO_ENABLE,
>  };
>  
>  enum iio_shared_by {
> diff --git a/include/linux/iio/types.h b/include/linux/iio/types.h
> index 9a1cc01..af0b6e0 100644
> --- a/include/linux/iio/types.h
> +++ b/include/linux/iio/types.h
> @@ -31,6 +31,7 @@ enum iio_chan_type {
>  	IIO_PRESSURE,
>  	IIO_HUMIDITYRELATIVE,
>  	IIO_ACTIVITY,
> +	IIO_STEPS,
>  };
>  
>  enum iio_modifier {
> @@ -74,6 +75,7 @@ enum iio_event_type {
>  	IIO_EV_TYPE_THRESH_ADAPTIVE,
>  	IIO_EV_TYPE_MAG_ADAPTIVE,
>  	IIO_EV_TYPE_TRANSITION,
> +	IIO_EV_TYPE_INSTANCE,
>  };
>  
>  enum iio_event_info {
> 
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