dt-bindings: serial: Add compatible for Renesas RZ/T2H SoC in sci

RSCI of RZ/T2H SoC (a.k.a r9a09g077), as a lot
of similarities with SCI in other Renesas SoC like G2L, G3S, V2L;
However, it has a different set of registers, and in addition to serial,
this IP also supports SCIe (encoder), SmartCard, i2c and spi.
This is why the 'renesas,sci' fallback for generic SCI does not apply for it.

Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Signed-off-by: Thierry Bultel <thierry.bultel.yh@bp.renesas.com>
Link: https://lore.kernel.org/r/20250403212919.1137670-4-thierry.bultel.yh@bp.renesas.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/devicetree/bindings/serial/renesas,rsci.yaml

@@ -0,0 +1,78 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/serial/renesas,rsci.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Renesas RSCI Serial Communication Interface
+
+maintainers:
+  - Geert Uytterhoeven <geert+renesas@glider.be>
+  - Thierry Bultel <thierry.bultel.yh@bp.renesas.com>
+
+allOf:
+  - $ref: serial.yaml#
+
+properties:
+  compatible:
+    const: renesas,r9a09g077-rsci      # RZ/T2H
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    items:
+      - description: Error interrupt
+      - description: Receive buffer full interrupt
+      - description: Transmit buffer empty interrupt
+      - description: Transmit end interrupt
+
+  interrupt-names:
+    items:
+      - const: eri
+      - const: rxi
+      - const: txi
+      - const: tei
+
+  clocks:
+    maxItems: 1
+
+  clock-names:
+    const: fck # UART functional clock
+
+  power-domains:
+    maxItems: 1
+
+  uart-has-rtscts: false
+
+required:
+  - compatible
+  - reg
+  - interrupts
+  - clocks
+  - clock-names
+  - power-domains
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/arm-gic.h>
+    #include <dt-bindings/clock/renesas-cpg-mssr.h>
+
+    aliases {
+        serial0 = &sci0;
+    };
+
+    sci0: serial@80005000 {
+        compatible = "renesas,r9a09g077-rsci";
+        reg = <0x80005000 0x400>;
+        interrupts = <GIC_SPI 590 IRQ_TYPE_LEVEL_HIGH>,
+                     <GIC_SPI 591 IRQ_TYPE_EDGE_RISING>,
+                     <GIC_SPI 592 IRQ_TYPE_EDGE_RISING>,
+                     <GIC_SPI 593 IRQ_TYPE_LEVEL_HIGH>;
+        interrupt-names = "eri", "rxi", "txi", "tei";
+        clocks = <&cpg CPG_MOD 108>;
+        clock-names = "fck";
+        power-domains = <&cpg>;
+    };