dt-bindings: iio: Add STM32 LPTimer quadrature encoder and counter

Add documentation for STMicroelectronics STM32 Low-Power Timer
quadrature encoder and counter binding.

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Acked-by: Jonathan Cameron <jic23@kernel.org>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

diff --git a/Documentation/devicetree/bindings/iio/counter/stm32-lptimer-cnt.txt b/Documentation/devicetree/bindings/iio/counter/stm32-lptimer-cnt.txt
new file mode 100644 (file)
index 0000000..a04aa5c
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/counter/stm32-lptimer-cnt.txt
@@ -0,0 +1,27 @@
+STMicroelectronics STM32 Low-Power Timer quadrature encoder and counter
+
+STM32 Low-Power Timer provides several counter modes. It can be used as:
+- quadrature encoder to detect angular position and direction of rotary
+  elements, from IN1 and IN2 input signals.
+- simple counter from IN1 input signal.
+
+Must be a sub-node of an STM32 Low-Power Timer device tree node.
+See ../mfd/stm32-lptimer.txt for details about the parent node.
+
+Required properties:
+- compatible:          Must be "st,stm32-lptimer-counter".
+- pinctrl-names:       Set to "default".
+- pinctrl-0:           List of phandles pointing to pin configuration nodes,
+                       to set IN1/IN2 pins in mode of operation for Low-Power
+                       Timer input on external pin.
+
+Example:
+       timer@40002400 {
+               compatible = "st,stm32-lptimer";
+               ...
+               counter {
+                       compatible = "st,stm32-lptimer-counter";
+                       pinctrl-names = "default";
+                       pinctrl-0 = <&lptim1_in_pins>;
+               };
+       };