iio: Implement counter channel type and info constants

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

Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

diff --git a/Documentation/ABI/testing/sysfs-bus-iio b/Documentation/ABI/testing/sysfs-bus-iio
index fee35c00cc4ed6fd59fdff3fd14cac396e9336a4..b8f220f978dd335389f7cae80e1e1eafb5fdde2d 100644 (file)
--- a/Documentation/ABI/testing/sysfs-bus-iio
+++ b/Documentation/ABI/testing/sysfs-bus-iio
@@ -329,6 +329,7 @@ What:               /sys/bus/iio/devices/iio:deviceX/in_pressure_scale
 What:          /sys/bus/iio/devices/iio:deviceX/in_humidityrelative_scale
 What:          /sys/bus/iio/devices/iio:deviceX/in_velocity_sqrt(x^2+y^2+z^2)_scale
 What:          /sys/bus/iio/devices/iio:deviceX/in_illuminance_scale
+What:          /sys/bus/iio/devices/iio:deviceX/in_countY_scale
 KernelVersion: 2.6.35
 Contact:       linux-iio@vger.kernel.org
 Description:
@@ -1579,3 +1580,20 @@ 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, multiplication by an available [Y]_scale results in
+               the counts of a single quadrature signal phase from channel Y.
+
+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. This attribute
+               provides an absolute positional reference (e.g. a pulse once per
+               revolution) which may be used to home positional systems as
+               required.

diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c
index fc340ed3dca1ca555dfa47cc02ae845d825279d3..649725bc15c1a5ee38a13345fe0d89272ca567f0 100644 (file)
--- 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[] = {

diff --git a/include/uapi/linux/iio/types.h b/include/uapi/linux/iio/types.h
index 22e5e589a2747beff6d59f40d44ce99364c85415..e54d14a7f876b08c8ff5bd370143d85a89c02ff5 100644 (file)
--- 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 {