linux-kernel - [PATCH v4 1/2] dt-bindings: gpio: add gpio-line-mux controller

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Message-ID: <20251105103607.393353-2-jelonek.jonas@gmail.com>
Date: Wed,  5 Nov 2025 10:36:05 +0000
From: Jonas Jelonek <jelonek.jonas@...il.com>
To: Linus Walleij <linus.walleij@...aro.org>,
	Bartosz Golaszewski <brgl@...ev.pl>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Peter Rosin <peda@...ntia.se>,
	Geert Uytterhoeven <geert+renesas@...der.be>
Cc: linux-gpio@...r.kernel.org,
	devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Thomas Richard <thomas.richard@...tlin.com>,
	Jonas Jelonek <jelonek.jonas@...il.com>,
	Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
Subject: [PATCH v4 1/2] dt-bindings: gpio: add gpio-line-mux controller

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@...il.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
---
 .../bindings/gpio/gpio-line-mux.yaml          | 109 ++++++++++++++++++
 1 file changed, 109 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..fb91500fa10f
--- /dev/null
+++ b/Documentation/devicetree/bindings/gpio/gpio-line-mux.yaml
@@ -0,0 +1,109 @@
+# 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@...il.com>
+
+description: |
+  A GPIO controller to provide virtual GPIOs for a 1-to-many input-only mapping
+  backed by a single shared GPIO and a multiplexer. A simple illustrated
+  example is
+
+            +----- A
+    IN     /
+    <-----o------- B
+        / |\
+        | | +----- C
+        | |  \
+        | |   +--- D
+        | |
+       M1 M0
+
+    MUX CONTROL
+
+     M1 M0   IN
+      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 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.
+    $ref: /schemas/types.yaml#/definitions/uint32-array
+
+  gpio-line-names: true
+
+  mux-controls:
+    $ref: /schemas/types.yaml#/definitions/phandle-array
+    maxItems: 1
+    description:
+      Phandle to the multiplexer to control access to the GPIOs.
+
+  ngpios: false
+
+  shared-gpios:
+    maxItems: 1
+    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-gpios
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+    #include <dt-bindings/mux/mux.h>
+
+    sfp_gpio_mux: mux-controller-1 {
+        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-gpios = <&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";
+
+        i2c-bus = <&sfp1_i2c>;
+        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>;
+    };
-- 
2.48.1