[PATCH v2 1/2] dt-bindings: gpio: add gpio-line-mux controller

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

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

The gpio-line-mux 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>
---
 .../bindings/gpio/gpio-line-mux.yaml          | 108 ++++++++++++++++++
 .../devicetree/bindings/mux/gpio-mux.yaml     |  30 +++++
 2 files changed, 138 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/gpio/gpio-line-mux.yaml

diff --git a/Documentation/devicetree/bindings/gpio/gpio-line-mux.yaml b/Documentation/devicetree/bindings/gpio/gpio-line-mux.yaml
new file mode 100644
index 000000000000..4c907a35eb4d
--- /dev/null
+++ b/Documentation/devicetree/bindings/gpio/gpio-line-mux.yaml
@@ -0,0 +1,108 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/gpio/gpio-line-mux.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: GPIO line mux
+
+maintainers:
+  - Jonas Jelonek <jelonek.jonas@gmail.com>
+
+description:
+  A GPIO controller to provide virtual GPIOs for a 1-to-many mapping backed by
+  a single shared GPIO and a multiplexer. A simple illustrated example is
+
+            +----- A
+    IN/OUT /
+    <-----o------- B
+        / |\
+        | | +----- C
+        | |  \
+        | |   +--- D
+        | |
+       M1 M0
+
+    MUX CONTROL
+
+     M1 M0   IN/OUT
+      0  0   A
+      0  1   B
+      1  0   C
+      1  1   D
+
+  This can be used in case a real GPIO is connected to multiple inputs/outputs
+  and controlled by a multiplexer, and another subsystem/driver does not work
+  directly with the multiplexer subsystem.
+
+properties:
+  compatible:
+    const: gpio-line-mux
+
+  gpio-controller: true
+
+  "#gpio-cells":
+    const: 2
+
+  gpio-line-mux-states:
+    description: Mux states corresponding to the virtual GPIOs.
+    minItems: 1
+    items:
+      type: string
+
+  gpio-line-names: true
+
+  mux-controls:
+    maxItems: 1
+    $ref: /schemas/mux/mux-controller.yaml#
+    description:
+      Phandle to the multiplexer to control access to the GPIOs.
+
+  ngpios: false
+
+  shared-gpio:
+    description:
+      GPIO which is the '1' in 1-to-many and is shared by the virtual GPIOs
+      and controlled via the mux.
+
+required:
+  - compatible
+  - gpio-controller
+  - gpio-line-mux-states
+  - 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 0 GPIO_ACTIVE_HIGH>,
+                    <&gpio0 1 GPIO_ACTIVE_HIGH>;
+        #mux-control-cells = <0>;
+        idle-state = <MUX_IDLE_AS_IS>;
+    };
+
+    sfp1_gpio: sfp-gpio-1 {
+        compatible = "gpio-line-mux";
+        gpio-controller;
+        #gpio-cells = <2>;
+
+        mux-controls = <&sfp_gpio_mux>;
+        shared-gpio = <&gpio0 2 GPIO_ACTIVE_HIGH>;
+
+        gpio-line-names = "SFP1_LOS", "SFP1_MOD_ABS", "SFP1_TX_FAULT";
+        gpio-line-mux-states = <0>, <1>, <3>;
+    };
+
+    sfp1: sfp-p1 {
+        compatible = "sff,sfp";
+
+        los-gpios = <&sfp1_gpio 0 GPIO_ACTIVE_HIGH>;
+        mod-def0-gpios = <&sfp1_gpio 1 GPIO_ACTIVE_LOW>;
+        tx-fault-gpios = <&sfp1_gpio 2 GPIO_ACTIVE_HIGH>;
+    };
diff --git a/Documentation/devicetree/bindings/mux/gpio-mux.yaml b/Documentation/devicetree/bindings/mux/gpio-mux.yaml
index ef7e33ec85d4..57eb1e9ef4cf 100644
--- a/Documentation/devicetree/bindings/mux/gpio-mux.yaml
+++ b/Documentation/devicetree/bindings/mux/gpio-mux.yaml
@@ -100,4 +100,34 @@ examples:
             };
         };
     };
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+
+    sfp_mux: mux-controller {
+        compatible = "gpio-mux";
+        #mux-control-cells = <0>;
+
+        mux-gpios = <&gpio0 0 GPIO_ACTIVE_HIGH>,
+                    <&gpio0 1 GPIO_ACTIVE_HIGH>;
+    };
+
+    sfp_gpio: sfp-gpio-1 {
+        compatible = "gpio-line-mux";
+        gpio-controller;
+        #gpio-cells = <2>;
+
+        mux-controls = <&sfp_mux>;
+        shared-gpio = <&gpio0 2 GPIO_ACTIVE_HIGH>;
+
+        gpio-line-names = "SFP_LOS", "SFP_MOD_ABS", "SFP_TX_F";
+        gpio-line-mux-states = <0>, <1>, <2>;
+    };
+
+    sfp0: sfp-p0 {
+        compatible = "sff,sfp";
+
+        los-gpios = <&sfp_gpio 0 GPIO_ACTIVE_HIGH>;
+        mod-def0-gpios = <&sfp_gpio 1 GPIO_ACTIVE_LOW>;
+        tx-fault-gpios = <&sfp_gpio 2 GPIO_ACTIVE_HIGH>;
+    };
 ...
-- 
2.48.1