dt-bindings: mfd: mediatek: Add bindings for MT6357 PMIC

Currently, almost all MT63XX PMIC are documented mfd/mt6397.txt.
Unfortunately, the PMICs haven't always similar HW sub-features.
To have a better human readable schema, I chose to make one PMIC schema
to match the exact HW capabilities instead of convert mt6397.txt to
mediatek,mt63xx.yaml and put a bunch of properties behind
"if contain ... then ..."

- add interrupt property
- change property refs to match with new yaml documentation

Reviewed-by: Krzysztof Kozlowski <[e-mail]>
Acked-by: Lee Jones <[e-mail]>
Signed-off-by: Alexandre Mergnat <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Matthias Brugger <[e-mail]>

Documentation/devicetree/bindings/mfd/mediatek,mt6357.yaml

···
+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/mfd/mediatek,mt6357.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: MediaTek MT6357 PMIC
+
+maintainers:
+  - Flora Fu <[e-mail]>
+  - Alexandre Mergnat <[e-mail]>
+
+description: |
+  MT6357 is a power management system chip containing 5 buck
+  converters and 29 LDOs. Supported features are audio codec,
+  USB battery charging, fuel gauge, RTC
+
+  This is a multifunction device with the following sub modules:
+  - Regulator
+  - RTC
+  - Keys
+
+  It is interfaced to host controller using SPI interface by a proprietary hardware
+  called PMIC wrapper or pwrap. This MFD is a child device of pwrap.
+  See the following for pwrap node definitions:
+  Documentation/devicetree/bindings/soc/mediatek/mediatek,pwrap.yaml
+
+properties:
+  compatible:
+    const: mediatek,mt6357
+
+  interrupts:
+    maxItems: 1
+
+  interrupt-controller: true
+
+  "#interrupt-cells":
+    const: 2
+
+  regulators:
+    type: object
+    $ref: /schemas/regulator/mediatek,mt6357-regulator.yaml
+    description:
+      List of MT6357 BUCKs and LDOs regulators.
+
+  rtc:
+    type: object
+    $ref: /schemas/rtc/rtc.yaml#
+    description:
+      MT6357 Real Time Clock.
+    properties:
+      compatible:
+        const: mediatek,mt6357-rtc
+      start-year: true
+    required:
+      - compatible
+
+  keys:
+    type: object
+    $ref: /schemas/input/mediatek,pmic-keys.yaml
+    description:
+      MT6357 power and home keys.
+
+required:
+  - compatible
+  - regulators
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/arm-gic.h>
+
+    pwrap {
+        pmic {
+            compatible = "mediatek,mt6357";
+
+            interrupt-parent = <&pio>;
+            interrupts = <145 IRQ_TYPE_LEVEL_HIGH>;
+            interrupt-controller;
+            #interrupt-cells = <2>;
+
+            regulators {
+                mt6357_vproc_reg: buck-vproc {
+                    regulator-name = "vproc";
+                    regulator-min-microvolt = <518750>;
+                    regulator-max-microvolt = <1312500>;
+                    regulator-ramp-delay = <6250>;
+                    regulator-enable-ramp-delay = <220>;
+                    regulator-always-on;
+                };
+
+                // ...
+
+                mt6357_vusb33_reg: ldo-vusb33 {
+                    regulator-name = "vusb33";
+                    regulator-min-microvolt = <3000000>;
+                    regulator-max-microvolt = <3100000>;
+                    regulator-enable-ramp-delay = <264>;
+                };
+            };
+
+            rtc {
+                compatible = "mediatek,mt6357-rtc";
+            };
+
+            keys {
+                compatible = "mediatek,mt6357-keys";
+            };
+        };
+    };