Chrome OS devices with PDCs allow the host to read port status and
control port behavior with UCSI commands sent to the embedded controller
(EC). Add documentation for cros-ec-ucsi node which loads the Chrome OS
UCSI driver.

Signed-off-by: Jameson Thies <jthies@google.com>
---
 .../bindings/chrome/google,cros-ec-ucsi.yaml  | 71 +++++++++++++++++++
 1 file changed, 71 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/chrome/google,cros-ec-ucsi.yaml

diff --git a/Documentation/devicetree/bindings/chrome/google,cros-ec-ucsi.yaml b/Documentation/devicetree/bindings/chrome/google,cros-ec-ucsi.yaml
new file mode 100644
index 000000000000..2121776e3ff0
--- /dev/null
+++ b/Documentation/devicetree/bindings/chrome/google,cros-ec-ucsi.yaml
@@ -0,0 +1,71 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/chrome/google,cros-ec-ucsi.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Google Chrome OS EC(Embedded Controller) UCSI driver.
+
+maintainers:
+  - Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
+  - Andrei Kuchynski <akuchynski@chromium.org>
+  - Benson Leung <bleung@chromium.org>
+  - Jameson Thies <jthies@google.com>
+  - Łukasz Bartosik <ukaszb@chromium.org>
+
+description:
+  Chrome OS devices with PDC-based USB-C ports expose a UCSI interface
+  from the Embedded Controller (EC) which allows the host to request
+  port state and control limited port behavior (DR/PR swap). This node
+  allows the host UCSI driver to send and receive UCSI commands to a
+  Chrome OS EC. The node for this device should be under a cros-ec node
+  like google,cros-ec-spi.
+
+properties:
+  compatible:
+    const: google,cros-ec-ucsi
+
+  '#address-cells':
+    const: 1
+
+  '#size-cells':
+    const: 0
+
+patternProperties:
+  '^connector@[0-9a-f]+$':
+    $ref: /schemas/connector/usb-connector.yaml#
+    required:
+      - reg
+
+required:
+  - compatible
+
+additionalProperties: false
+
+examples:
+  - |+
+    spi {
+      #address-cells = <1>;
+      #size-cells = <0>;
+
+      cros_ec: ec@0 {
+        compatible = "google,cros-ec-spi";
+        reg = <0>;
+        interrupts = <35 0>;
+
+        typec {
+          compatible = "google,cros-ec-ucsi";
+
+          #address-cells = <1>;
+          #size-cells = <0>;
+
+          connector@0 {
+            compatible = "usb-c-connector";
+            reg = <0>;
+            power-role = "dual";
+            data-role = "dual";
+            try-power-role = "source";
+          };
+        };
+      };
+    };
-- 
2.51.0.570.gb178f27e6d-goog

On Tue, 30 Sep 2025 01:23:46 +0000, Jameson Thies wrote:
> Chrome OS devices with PDCs allow the host to read port status and
> control port behavior with UCSI commands sent to the embedded controller
> (EC). Add documentation for cros-ec-ucsi node which loads the Chrome OS
> UCSI driver.
> 
> Signed-off-by: Jameson Thies <jthies@google.com>
> ---
>  .../bindings/chrome/google,cros-ec-ucsi.yaml  | 71 +++++++++++++++++++
>  1 file changed, 71 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/chrome/google,cros-ec-ucsi.yaml
> 

My bot found errors running 'make dt_binding_check' on your patch:

yamllint warnings/errors:

dtschema/dtc warnings/errors:
/builds/robherring/dt-review-ci/linux/Documentation/devicetree/bindings/chrome/google,cros-ec-ucsi.example.dtb: ec@0 (google,cros-ec-spi): typec:compatible:0: 'google,cros-ec-typec' was expected
	from schema $id: http://devicetree.org/schemas/mfd/google,cros-ec.yaml#

doc reference errors (make refcheckdocs):

See https://patchwork.ozlabs.org/project/devicetree-bindings/patch/20250930012352.413066-2-jthies@google.com

The base for the series is generally the latest rc1. A different dependency
should be noted in *this* patch.

If you already ran 'make dt_binding_check' and didn't see the above
error(s), then make sure 'yamllint' is installed and dt-schema is up to
date:

pip3 install dtschema --upgrade

Please check and re-submit after running the above command yourself. Note
that DT_SCHEMA_FILES can be set to your schema file to speed up checking
your schema. However, it must be unset to test all examples with your schema.

> My bot found errors running 'make dt_binding_check' on your patch:

Thanks for catching this. I did run "make dt_binding_check
DT_SCHEMA_FILES=google,cros-ec-ucsi.yaml" to check the newly added
yaml file. But I didn't check google,cros-ec.yaml or any of the DTS
files with "make dtbs_check" so I missed this regression. I'll follow
up with a v2 series and test all bindings with "make dt_binding_check"
and "make dtbs_check".