[RFC PATCH v1 1/2] dt-bindings: gpio: add gpio-split controller

[Jonas Jelonek <jelonek.jonas@gmail.com>]

Add dt-schema for a virtual gpio-split controller which exposes virtual
GPIOs for a shared GPIO controlled by a multiplexer, e.g. a gpio-mux.

The gpio-split controller is a gpio-controller, thus has mostly the same
semantics. However, it requires a mux-control to be specified upon which
it will operate.

Signed-off-by: Jonas Jelonek <jelonek.jonas@gmail.com>
---
 .../devicetree/bindings/gpio/gpio-split.yaml  | 77 +++++++++++++++++++
 1 file changed, 77 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/gpio/gpio-split.yaml

diff --git a/Documentation/devicetree/bindings/gpio/gpio-split.yaml b/Documentation/devicetree/bindings/gpio/gpio-split.yaml
new file mode 100644
index 000000000000..9a58c81da4fa
--- /dev/null
+++ b/Documentation/devicetree/bindings/gpio/gpio-split.yaml
@@ -0,0 +1,77 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/gpio/gpio-split.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: GPIO split
+
+maintainers:
+  - Jonas Jelonek <jelonek.jonas@gmail.com>
+
+description:
+  A virtual GPIO controller to provide virtual GPIOs backed by a single real
+  GPIO and a multiplexer. This controller may be used in case a real GPIO is
+  connected to multiple inputs/outputs and controlled by a multiplexer, and
+  another subsystem/driver is not able to work with multiplexer subsystem.
+
+properties:
+  compatible:
+    const: gpio-split
+
+  gpio-controller: true
+
+  "#gpio-cells":
+    const: 2
+
+  gpio-line-names: true
+
+  mux-controls:
+    maxItems: 1
+
+  ngpios: false
+
+  shared-gpio:
+    description:
+      GPIO that is shared by the virtual GPIOs and controlled via the mux.
+
+required:
+  - compatible
+  - gpio-controller
+  - mux-controls
+  - shared-gpio
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+    #include <dt-bindings/mux/mux.h>
+
+    sfp_gpio_mux: gpio-mux {
+        compatible = "gpio-mux";
+        mux-gpios = <&gpio0 12 GPIO_ACTIVE_HIGH>,
+                    <&gpio0 14 GPIO_ACTIVE_HIGH>;
+        #mux-control-cells = <0>;
+        idle-state = <MUX_IDLE_AS_IS>;
+    };
+
+    sfp1_gpio: sfp-gpio-1 {
+        compatible = "gpio-split";
+        gpio-controller;
+        #gpio-cells = <2>;
+
+        mux-controls = <&sfp_gpio_mux>;
+        shared-gpio = <&gpio0 19 GPIO_ACTIVE_HIGH>;
+
+        gpio-line-names = "SFP1_LOS", "SFP1_MOD_ABS", "SFP1_TX_FAULT";
+        gpio-0 {
+            mux-state = <0>;
+        };
+        gpio-1 {
+            mux-state = <1>;
+        };
+        gpio-2 {
+            mux-state = <3>;
+        };
+    };
-- 
2.48.1