On 03/09/2018 10:42 AM, William Breathitt Gray wrote:
> This patch adds high-level documentation about the Generic Counter
> interface.
>
> Signed-off-by: William Breathitt Gray <vilhelm.gray@xxxxxxxxx>
> ---
> Documentation/driver-api/generic-counter.rst | 321 +++++++++++++++++++++++++++
> Documentation/driver-api/index.rst | 1 +
> MAINTAINERS | 1 +
> 3 files changed, 323 insertions(+)
> create mode 100644 Documentation/driver-api/generic-counter.rst
>
> diff --git a/Documentation/driver-api/generic-counter.rst b/Documentation/driver-api/generic-counter.rst
> new file mode 100644
> index 000000000000..bce0cbc31963
> --- /dev/null
> +++ b/Documentation/driver-api/generic-counter.rst
> @@ -0,0 +1,321 @@
[snip]
> +There are three core components to a counter:
> +
> + COUNT
> + -----
> + A Count represents the count data for a set of Signals. The
> + Generic Counter interface provides the following available count
> + data types:
> +
> + * COUNT_POSITION_UNSIGNED:
> + Unsigned integer value representing position.
> +
> + * COUNT_POSITION_SIGNED:
> + Signed integer value representing position.
> +
> + A Count has a count function mode which represents the update
> + behavior for the count data. The Generic Counter interface
> + provides the following available count function modes:
> +
> + * Increase:
> + Accumulated count is incremented.
> +
> + * Decrease:
> + Accumulated count is decremented.
> +
> + * Pulse-Direction:
> + Rising edges on quadrature pair signal A updates
> + the respective count. The input level of
> + quadrature pair signal B determines direction.
> +
> + * Quadrature x1:
> + If direction is forward, rising edges on
> + quadrature pair signal A updates the respective
> + count; if the direction is backward, falling
> + edges on quadrature pair signal A updates the
> + respective count. Quadrature encoding determines
> + the direction.
> +
> + * Quadrature x2:
> + Any state transition on quadrature pair signal A
> + updates the respective count. Quadrature
> + encoding determines the direction.
> +
> + * Quadrature x4:
> + Any state transition on either quadrature pair
> + signals updates the respective count. Quadrature
change <TAB> ^^^ to <SPACE>
> + encoding determines the direction.
> +
> + A Count has a set of one or more associated Signals.
> +
> + SIGNAL
> + ------
> + A Signal represents a counter input data; this is the input data
> + that is analyzed by the counter to determine the count data;
> + e.g. a quadrature signal output line of a rotary encoder. Not
> + all counter devices provide user access to the Signal data.
> +
> + The Generic Counter interface provides the following available
> + signal data types for when the Signal data is available for user
> + access:
> +
> + * SIGNAL_LEVEL_LOW:
> + Signal line is in a low state.
> +
> + * SIGNAL_LEVEL_HIGH:
> + Signal line is in a high state.
> +
> + A Signal may be associated to one or more Counts.
with (?)
Hm, there are around 8 or so instances of "associated to" here -- and at least
one of "associated with" (to my surprise :). But it's no big deal.
Reviewed-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
thanks,
--
~Randy
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