[PATCH 1/3] dt-bindings: i3c: renesas,i3c: Document analog noise filter control

[Diogo Ivo]

The analog noise filter for the input terminals (I3C_SDA, I3C_SCL) of
the Renesas I3C controller is controlled through the SYS_I3C_CFG
register of the system controller. Document the
renesas,analog-noise-filter property, which references the system
controller together with the offset of the SYS_I3C_CFG register and
the state of the filter: 1 enables the filter and 0 bypasses it.

The property is optional: device trees not providing it keep the
filter at its reset value.

Signed-off-by: Diogo Ivo <diogo.ivo.sx at renesas.com>
---
 .../devicetree/bindings/i3c/renesas,i3c.yaml          | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/Documentation/devicetree/bindings/i3c/renesas,i3c.yaml b/Documentation/devicetree/bindings/i3c/renesas,i3c.yaml
index 08fcea89a015..381807844351 100644
--- a/Documentation/devicetree/bindings/i3c/renesas,i3c.yaml
+++ b/Documentation/devicetree/bindings/i3c/renesas,i3c.yaml
@@ -96,6 +96,25 @@ properties:
       - const: presetn
       - const: tresetn
 
+  renesas,analog-noise-filter:
+    $ref: /schemas/types.yaml#/definitions/phandle-array
+    description:
+      Analog noise filter for the I3C input signals (I3C_SDA, I3C_SCL),
+      controlled through the SYS_I3C_CFG register of the system
+      controller (SYSC). Three entries specifying the system controller,
+      the offset of the SYS_I3C_CFG register and the state of the filter.
+      If not present, the filter keeps its reset state.
+    items:
+      - items:
+          - description: phandle to the system controller node
+          - description: offset of the SYS_I3C_CFG register within the SYSC
+          - enum: [0, 1]
+            description: |
+              state of the analog noise filter:
+               - 1: enable the filter, performing noise reduction on the
+                 I3C_SDA and I3C_SCL input signals
+               - 0: bypass the filter
+
 required:
   - compatible
   - reg

-- 
2.56.0