[PATCH v2 1/3] dt-bindings: embedded-controller: Add Lenovo ThinkPad X13s EC

[Clover <alex@ironrobin.net>]

Add a standalone binding for the embedded controller in the Lenovo
ThinkPad X13s. Although its I2C command transport resembles that of the
T14s EC, its keyboard-backlight, event and power-management interfaces
differ.

Describe the event interrupt and the separate host-controlled power-state
signal, which is high during normal operation and low in the low-power
state. Require this GPIO and allow wakeup-source to describe wake
capability.

Assisted-by: LLM
Signed-off-by: Clover <alex@ironrobin.net>

---
diff --git a/Documentation/devicetree/bindings/embedded-controller/lenovo,thinkpad-x13s-ec.yaml b/Documentation/devicetree/bindings/embedded-controller/lenovo,thinkpad-x13s-ec.yaml
new file mode 100644
--- /dev/null
+++ b/Documentation/devicetree/bindings/embedded-controller/lenovo,thinkpad-x13s-ec.yaml
@@ -0,0 +1,65 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/embedded-controller/lenovo,thinkpad-x13s-ec.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Lenovo ThinkPad X13s Embedded Controller
+
+maintainers:
+  - Clover <alex@ironrobin.net>
+
+description:
+  The Lenovo ThinkPad X13s has an I2C-connected embedded controller (EC)
+  providing keyboard backlight control and event notifications. In addition
+  to its event interrupt, the EC has a separate host-controlled power-state
+  input used during transitions between normal operation and low power.
+
+properties:
+  compatible:
+    const: lenovo,thinkpad-x13s-ec
+
+  reg:
+    const: 0x28
+
+  interrupts:
+    maxItems: 1
+
+  power-state-gpios:
+    maxItems: 1
+    description:
+      GPIO connected to the EC power-state input, driven by the host.
+      The signal is high during normal operation and low in the low-power
+      state. It is used together with I2C power-state commands, rather than
+      as a power-supply enable or reset signal. The GPIO is active high.
+
+  wakeup-source: true
+
+required:
+  - compatible
+  - reg
+  - interrupts
+  - power-state-gpios
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+    #include <dt-bindings/interrupt-controller/irq.h>
+
+    i2c {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        embedded-controller@28 {
+            compatible = "lenovo,thinkpad-x13s-ec";
+            reg = <0x28>;
+            interrupts-extended = <&gpio 1 IRQ_TYPE_EDGE_FALLING>;
+            power-state-gpios = <&gpio 2 GPIO_ACTIVE_HIGH>;
+            pinctrl-0 = <&ec_int_n>, <&ec_power_state>;
+            pinctrl-names = "default";
+            wakeup-source;
+        };
+    };
+...