ASoC: dt-bindings: maxim,max98504: Convert to DT schema

Convert the Maxim Integrated MAX98504 amplifier bindings to DT schema.
Few properties are made optional:
1. interrupts: current Linux driver implementation does not use them,
2. supplies: on some boards these might be wired to battery, for which
   no regulator is provided.

Signed-off-by: Krzysztof Kozlowski <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Mark Brown <[email protected]>

Author: krzk

Documentation/devicetree/bindings/sound/max98504.txt

@@ -0,0 +1,86 @@
+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/sound/maxim,max98504.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Maxim Integrated MAX98504 class D mono speaker amplifier
+
+maintainers:
+  - Krzysztof Kozlowski <[email protected]>
+
+description:
+  Maxim Integrated MAX98504 speaker amplifier supports I2C control interface
+  with an IRQ output signal, PCM and PDM digital audio interface (DAI) and a
+  differential analog input.
+
+properties:
+  compatible:
+    const: maxim,max98504
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+  DIOVDD-supply: true
+  DVDD-supply: true
+  PVDD-supply: true
+
+  maxim,brownout-threshold:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    maximum: 21
+    default: 0
+    description:
+      PVDD brownout threshold, where values correspond to 2.6V, 2.65V...3.65V
+      voltage range.  Property also enables the PVDD brownout protection.
+
+  maxim,brownout-attenuation:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    maximum: 6
+    default: 0
+    description:
+      Brownout attenuation to the speaker gain applied during the "attack hold"
+      and "timed hold" phase, the value must be from 0...6 (dB) range.
+
+  maxim,brownout-attack-hold-ms:
+    maximum: 255
+    default: 0
+    description:
+      Brownout attack hold phase time in ms, VBATBROWN_ATTK_HOLD, register 0x0018.
+
+  maxim,brownout-timed-hold-ms:
+    maximum: 255
+    default: 0
+    description:
+      Brownout timed hold phase time in ms, VBATBROWN_TIME_HOLD, register 0x0019.
+
+  maxim,brownout-release-rate-ms:
+    maximum: 255
+    default: 0
+    description:
+      Brownout release phase step time in ms, VBATBROWN_RELEASE, register 0x001A.
+
+required:
+  - compatible
+  - reg
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+
+    i2c {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        amplifier@31 {
+            compatible = "maxim,max98504";
+            reg = <0x31>;
+
+            DIOVDD-supply = <&ldo3_reg>;
+            DVDD-supply = <&ldo3_reg>;
+        };
+    };