dt-bindings: embedded-controller: Add Lenovo Thinkpad T14s EC

Add binding for the EC found in the Thinkpad T14s Gen6 Snapdragon,
which is based on the Qualcomm X1 Elite. Some of the system LEDs
and extra keys are only accessible via the EC.

Reviewed-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Sebastian Reichel <sre@kernel.org>
Acked-by: Rob Herring (Arm) <robh@kernel.org>
Link: https://patch.msgid.link/20250918-thinkpad-t14s-ec-v5-1-ac0bc6382c5c@collabora.com
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

Documentation/devicetree/bindings/embedded-controller/lenovo,thinkpad-t14s-ec.yaml

@@ -0,0 +1,50 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/embedded-controller/lenovo,thinkpad-t14s-ec.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Lenovo Thinkpad T14s Embedded Controller
+
+maintainers:
+  - Sebastian Reichel <sre@kernel.org>
+
+description:
+  The Qualcomm Snapdragon-based Lenovo Thinkpad T14s has an Embedded Controller
+  (EC) which handles things such as keyboard backlight, LEDs or non-standard
+  keys.
+
+properties:
+  compatible:
+    const: lenovo,thinkpad-t14s-ec
+
+  reg:
+    const: 0x28
+
+  interrupts:
+    maxItems: 1
+
+  wakeup-source: true
+
+required:
+  - compatible
+  - reg
+  - interrupts
+
+additionalProperties: false
+
+examples:
+  - |+
+    #include <dt-bindings/interrupt-controller/irq.h>
+    i2c {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        embedded-controller@28 {
+            compatible = "lenovo,thinkpad-t14s-ec";
+            reg = <0x28>;
+            interrupts-extended = <&tlmm 66 IRQ_TYPE_LEVEL_LOW>;
+            wakeup-source;
+        };
+    };
+...