Re: [PATCH v4 1/2] iio: Implement counter channel type and info constants

[Jonathan Cameron <jic23@kernel.org>]

On 21/09/16 21:15, William Breathitt Gray wrote:
> Quadrature encoders, such as rotary encoders and linear encoders, are
> devices which are capable of encoding the relative position and
> direction of motion of a shaft. This patch introduces several IIO
> constants for supporting quadrature encoder counter devices.
> 
>   IIO_COUNT: Current count (main data provided by the counter device)
>   IIO_INDEX: Counter device index value
>   IIO_CHAN_INFO_PRESET: Counter preset value
> 
> Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
> ---
>  Documentation/ABI/testing/sysfs-bus-iio | 28 ++++++++++++++++++++++++++++
>  drivers/iio/industrialio-core.c         |  3 +++
>  include/linux/iio/iio.h                 |  1 +
>  include/uapi/linux/iio/types.h          |  2 ++
>  4 files changed, 34 insertions(+)
> 
> diff --git a/Documentation/ABI/testing/sysfs-bus-iio b/Documentation/ABI/testing/sysfs-bus-iio
> index fee35c0..be66a41 100644
> --- a/Documentation/ABI/testing/sysfs-bus-iio
> +++ b/Documentation/ABI/testing/sysfs-bus-iio
> @@ -1579,3 +1579,31 @@ Contact:	linux-iio@vger.kernel.org
>  Description:
>  		Raw (unscaled no offset etc.) electric conductivity reading that
>  		can be processed to siemens per meter.
> +
> +What:		/sys/bus/iio/devices/iio:deviceX/in_countY_raw
> +KernelVersion:	4.9
> +Contact:	linux-iio@vger.kernel.org
> +Description:
> +		Raw counter device counts from channel Y. For quadrature
> +		counters, division by an available [Y]_scale results in the
> +		counts of a single quadrature signal phase from channel Y.
Division?  Needs to be multiplication to be consistent with the other
interfaces.  
> +
> +What:		/sys/bus/iio/devices/iio:deviceX/in_countY_scale
> +KernelVersion:	4.9
> +Contact:	linux-iio@vger.kernel.org
> +Description:
> +		If a scale value is available for channel Y, it is provided by
> +		this attribute.
Can just add the What line to the big block of _scale attributes already
listed.  Generic text should cover it fine.
> +
> +What:		/sys/bus/iio/devices/iio:deviceX/in_countY_preset
> +KernelVersion:	4.9
> +Contact:	linux-iio@vger.kernel.org
> +Description:
> +		If the counter device supports preset registers, the preset
> +		count for channel Y is provided by this attribute.
> +
> +What:		/sys/bus/iio/devices/iio:deviceX/in_indexY_raw
> +KernelVersion:	4.9
> +Contact:	linux-iio@vger.kernel.org
> +Description:
> +		Raw counter device index value from channel Y.
Needs more description.  Don't assume people have any idea what an 'index'
value is on a counter.
> diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c
> index fc340ed..ed175a2 100644
> --- a/drivers/iio/industrialio-core.c
> +++ b/drivers/iio/industrialio-core.c
> @@ -81,6 +81,8 @@ static const char * const iio_chan_type_name_spec[] = {
>  	[IIO_PH] = "ph",
>  	[IIO_UVINDEX] = "uvindex",
>  	[IIO_ELECTRICALCONDUCTIVITY] = "electricalconductivity",
> +	[IIO_COUNT] = "count",
> +	[IIO_INDEX] = "index",
>  };
>  
>  static const char * const iio_modifier_names[] = {
> @@ -151,6 +153,7 @@ static const char * const iio_chan_info_postfix[] = {
>  	[IIO_CHAN_INFO_DEBOUNCE_TIME] = "debounce_time",
>  	[IIO_CHAN_INFO_CALIBEMISSIVITY] = "calibemissivity",
>  	[IIO_CHAN_INFO_OVERSAMPLING_RATIO] = "oversampling_ratio",
> +	[IIO_CHAN_INFO_PRESET] = "preset",
>  };
>  
>  /**
> diff --git a/include/linux/iio/iio.h b/include/linux/iio/iio.h
> index b4a0679..7dc86d1 100644
> --- a/include/linux/iio/iio.h
> +++ b/include/linux/iio/iio.h
> @@ -46,6 +46,7 @@ enum iio_chan_info_enum {
>  	IIO_CHAN_INFO_DEBOUNCE_TIME,
>  	IIO_CHAN_INFO_CALIBEMISSIVITY,
>  	IIO_CHAN_INFO_OVERSAMPLING_RATIO,
> +	IIO_CHAN_INFO_PRESET,
>  };
>  
>  enum iio_shared_by {
> diff --git a/include/uapi/linux/iio/types.h b/include/uapi/linux/iio/types.h
> index 22e5e58..e54d14a 100644
> --- a/include/uapi/linux/iio/types.h
> +++ b/include/uapi/linux/iio/types.h
> @@ -40,6 +40,8 @@ enum iio_chan_type {
>  	IIO_PH,
>  	IIO_UVINDEX,
>  	IIO_ELECTRICALCONDUCTIVITY,
> +	IIO_COUNT,
> +	IIO_INDEX,
>  };
>  
>  enum iio_modifier {
>