dt-bindings: hwmon: Support Aspeed g6 PWM TACH Control

Document the compatible for aspeed,ast2600-pwm-tach device, which can
support up to 16 PWM outputs and 16 fan tach input.

Signed-off-by: Billy Tsai <[e-mail]>
Reviewed-by: Rob Herring <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Guenter Roeck <[e-mail]>

Documentation/devicetree/bindings/hwmon/aspeed,g6-pwm-tach.yaml

···
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+# Copyright (C) 2023 Aspeed, Inc.
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/hwmon/aspeed,g6-pwm-tach.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: ASPEED G6 PWM and Fan Tach controller
+
+maintainers:
+  - Billy Tsai <[e-mail]>
+
+description: |
+  The ASPEED PWM controller can support up to 16 PWM outputs.
+  The ASPEED Fan Tacho controller can support up to 16 fan tach input.
+  They are independent hardware blocks, which are different from the
+  previous version of the ASPEED chip.
+
+properties:
+  compatible:
+    enum:
+      - aspeed,ast2600-pwm-tach
+
+  reg:
+    maxItems: 1
+
+  clocks:
+    maxItems: 1
+
+  resets:
+    maxItems: 1
+
+  "#pwm-cells":
+    const: 3
+
+patternProperties:
+  "^fan-[0-9]+$":
+    $ref: fan-common.yaml#
+    unevaluatedProperties: false
+    required:
+      - tach-ch
+
+required:
+  - reg
+  - clocks
+  - resets
+  - "#pwm-cells"
+  - compatible
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/clock/aspeed-clock.h>
+    pwm_tach: pwm-tach-controller@1e610000 {
+      compatible = "aspeed,ast2600-pwm-tach";
+      reg = <0x1e610000 0x100>;
+      clocks = <&syscon ASPEED_CLK_AHB>;
+      resets = <&syscon ASPEED_RESET_PWM>;
+      #pwm-cells = <3>;
+
+      fan-0 {
+        tach-ch = /bits/ 8 <0x0>;
+        pwms = <&pwm_tach 0 40000 0>;
+      };
+
+      fan-1 {
+        tach-ch = /bits/ 8 <0x1 0x2>;
+        pwms = <&pwm_tach 1 40000 0>;
+      };
+    };