dt-bindings: serial: describe SA8255p

SA8255p platform abstracts resources such as clocks, interconnect and
GPIO pins configuration in Firmware. SCMI power and perf protocols are
used to send request for resource configurations.

Add DT bindings for the QUP GENI UART controller on sa8255p platform.

The wakeup interrupt (IRQ) is treated as optional, as not all UART
instances have a wakeup-capable interrupt routed via the PDC.

Signed-off-by: Nikunj Kela <[e-mail]>
Co-developed-by: Praveen Talari <[e-mail]>
Signed-off-by: Praveen Talari <[e-mail]>
Reviewed-by: Krzysztof Kozlowski <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

Documentation/devicetree/bindings/serial/qcom,sa8255p-geni-uart.yaml

···
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/serial/qcom,sa8255p-geni-uart.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Qualcomm Geni based QUP UART interface
+
+maintainers:
+  - Praveen Talari <[e-mail]>
+
+allOf:
+  - $ref: /schemas/serial/serial.yaml#
+
+properties:
+  compatible:
+    enum:
+      - qcom,sa8255p-geni-uart
+      - qcom,sa8255p-geni-debug-uart
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    minItems: 1
+    items:
+      - description: UART core irq
+      - description: Wakeup irq (RX GPIO)
+
+  interrupt-names:
+    description:
+      The UART interrupt and optionally the RX in-band wakeup interrupt
+      as not all UART instances have a wakeup-capable interrupt routed
+      via the PDC.
+    minItems: 1
+    items:
+      - const: uart
+      - const: wakeup
+
+  power-domains:
+    minItems: 2
+    maxItems: 2
+
+  power-domain-names:
+    items:
+      - const: power
+      - const: perf
+
+required:
+  - compatible
+  - reg
+  - interrupts
+  - power-domains
+  - power-domain-names
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/arm-gic.h>
+
+    serial@990000 {
+        compatible = "qcom,sa8255p-geni-uart";
+        reg = <0x990000 0x4000>;
+        interrupts = <GIC_SPI 531 IRQ_TYPE_LEVEL_HIGH>;
+        power-domains = <&scmi0_pd 0>, <&scmi0_dvfs 0>;
+        power-domain-names = "power", "perf";
+    };
+...