[RFCv2 PATCH 1/4] dt-bindings: bus: add Wiegand bus dt documentation

["Martin Zaťovič" <m.zatovic1@gmail.com>]

This patch documents the devicetree entry for enabling Wiegand
bus driver. The drivers that will use Wiegand bus driver shall
create a sub-node of the documented node.

Signed-off-by: Martin Zaťovič <m.zatovic1@gmail.com>
---
Hello again,

this is the second round of RFC patches in an attempt to add Wiegand
driver to linux kernel. Thank you for all the issues you have pointed
out in the first round. I have tried to fix all of them and I have
also implemented a Wiegand bus driver, that is now used by the GPIO
driver itself - as suggested by Linus.

Any advice you have for me regarding the patches will be appreciated!

With regards,
Martin Zaťovič
---
 .../devicetree/bindings/bus/wiegand.yaml      | 50 +++++++++++++++++++
 1 file changed, 50 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/bus/wiegand.yaml

diff --git a/Documentation/devicetree/bindings/bus/wiegand.yaml b/Documentation/devicetree/bindings/bus/wiegand.yaml
new file mode 100644
index 000000000000..1ed863ab925c
--- /dev/null
+++ b/Documentation/devicetree/bindings/bus/wiegand.yaml
@@ -0,0 +1,50 @@
+# SPDX-License-Identifier: GPL-2.0
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/bus/wiegand.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Wiegand Bus
+
+maintainers:
+  - Martin Zaťovič <m.zatovic1@gmail.com>
+
+description: |
+  Wiegand interface is a wiring standard popularized in the 1980s. To this day
+  many card readers, fingerprint readers, sensors, etc. use Wiegand interface
+  particularly for access control applications. It utilizes two wires to
+  transmit the data - D0 and D1.
+
+  Both data lines are initially pulled up. To send a bit of value 1, the D1
+  line is set low. Similarly to send a bit of value 0, the D0 line is set low.
+
+properties:
+  $nodename:
+    pattern: "^wiegand(@[0-9a-f]+)?$"
+
+  compatible:
+    contains:
+      const: wiegand
+
+required:
+  - compatible
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+
+    wiegand {
+        compatible = "wiegand";
+
+        wiegand-gpio {
+            compatible = "wiegand,wiegand-gpio";
+            pinctrl-names = "default";
+            pinctrl-0 = <&pinctrl_uart2_wiegand>;
+            data-hi-gpios = <&gpio 7 (GPIO_ACTIVE_HIGH|GPIO_OPEN_DRAIN)>;
+            data-lo-gpios = <&gpio 6 (GPIO_ACTIVE_HIGH|GPIO_OPEN_DRAIN)>;
+        };
+    };
+
+...
-- 
2.37.3