regulator: dt-bindings: Add Renesas RAA215300 PMIC bindings

Document Renesas RAA215300 PMIC bindings.

The RAA215300 is a high Performance 9-Channel PMIC supporting DDR
Memory, with Built-In Charger and RTC.

It supports DDR3, DDR3L, DDR4, and LPDDR4 memory power requirements.
The internally compensated regulators, built-in Real-Time Clock (RTC),
32kHz crystal oscillator, and coin cell battery charger provide a
highly integrated, small footprint power solution ideal for
System-On-Module (SOM) applications. A spread spectrum feature
provides an ease-of-use solution for noise-sensitive audio or RF
applications.
Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/Message-Id: <20230623140948.384762-2-biju.das.jz@bp.renesas.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/regulator/renesas,raa215300.yaml

+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/regulator/renesas,raa215300.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Renesas RAA215300 Power Management Integrated Circuit (PMIC)
+
+maintainers:
+  - Biju Das <biju.das.jz@bp.renesas.com>
+
+description: |
+  The RAA215300 is a high-performance, low-cost 9-channel PMIC designed for
+  32-bit and 64-bit MCU and MPU applications. It supports DDR3, DDR3L, DDR4,
+  and LPDDR4 memory power requirements. The internally compensated regulators,
+  built-in Real-Time Clock (RTC), 32kHz crystal oscillator, and coin cell
+  battery charger provide a highly integrated, small footprint power solution
+  ideal for System-On-Module (SOM) applications. A spread spectrum feature
+  provides an ease-of-use solution for noise-sensitive audio or RF applications.
+
+  This device exposes two devices via I2C. One for the integrated RTC IP, and
+  one for everything else.
+
+  Link to datasheet:
+  https://www.renesas.com/in/en/products/power-power-management/multi-channel-power-management-ics-pmics/ssdsoc-power-management-ics-pmic-and-pmus/raa215300-high-performance-9-channel-pmic-supporting-ddr-memory-built-charger-and-rtc
+
+properties:
+  compatible:
+    enum:
+      - renesas,raa215300
+
+  reg:
+    maxItems: 2
+
+  reg-names:
+    items:
+      - const: main
+      - const: rtc
+
+  interrupts:
+    maxItems: 1
+
+  clocks:
+    description: |
+      The clocks are optional. The RTC is disabled, if no clocks are
+      provided(either xin or clkin).
+    maxItems: 1
+
+  clock-names:
+    description: |
+      Use xin, if connected to an external crystal.
+      Use clkin, if connected to an external clock signal.
+    enum:
+      - xin
+      - clkin
+
+required:
+  - compatible
+  - reg
+  - reg-names
+
+additionalProperties: false
+
+examples:
+  - |
+    /* 32.768kHz crystal */
+    x2: x2-clock {
+        compatible = "fixed-clock";
+        #clock-cells = <0>;
+        clock-frequency = <32768>;
+    };
+
+    i2c {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        raa215300: pmic@12 {
+            compatible = "renesas,raa215300";
+            reg = <0x12>, <0x6f>;
+            reg-names = "main", "rtc";
+
+            clocks = <&x2>;
+            clock-names = "xin";
+        };
+    };