[PATCH 2/4] dt-bindings: mfd: Add UGREEN NASync DH2300 MCU

[Krzysztof Kozlowski]

On Fri, Jun 12, 2026 at 07:34:15PM +0400, Alexey Charkov wrote:
> Document the UGREEN NASync DH2300 embedded controller (HC32F005 MCU),
> which is responsible for gating the SATA drive-bay power rail and
> providing a hardware watchdog.
> 
> This is based on disassebly of a GPL binary from vendor firmware for which
> no source code could be found, so parts of it can be inaccurate. Only
> the power gating function is confirmed.
> 
> Signed-off-by: Alexey Charkov <alchark at flipper.net>
> ---
>  .../devicetree/bindings/mfd/ugreen,dh2300-mcu.yaml | 62 ++++++++++++++++++++++
>  MAINTAINERS                                        |  5 ++
>  2 files changed, 67 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/mfd/ugreen,dh2300-mcu.yaml b/Documentation/devicetree/bindings/mfd/ugreen,dh2300-mcu.yaml
> new file mode 100644
> index 000000000000..847970c609cd
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/mfd/ugreen,dh2300-mcu.yaml

Place it in embedded-controller

> @@ -0,0 +1,62 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/mfd/ugreen,dh2300-mcu.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: UGREEN NASync DH2300 embedded controller
> +
> +maintainers:
> +  - Alexey Charkov <alchark at flipper.net>
> +
> +description:
> +  The UGREEN NASync DH2300 NAS carries a HC32F005 microcontroller on I2C that
> +  acts as a board embedded controller. It gates power to the SATA drive bays
> +  through an internal register and apparently also serves as a watchdog
> +  (unconfirmed, as vendor kernel sources are unavailable, works without it)
> +
> +properties:
> +  compatible:
> +    const: ugreen,dh2300-mcu
> +
> +  reg:
> +    maxItems: 1
> +
> +  regulator:

This should have specific name matching the actual regulator name, e.g.
pin.

> +    type: object
> +    $ref: /schemas/regulator/regulator.yaml#
> +    unevaluatedProperties: false
> +    description:
> +      The SATA drive-bay power gate controlled by the MCU.
> +
> +  watchdog-gpios:
> +    description:
> +      Optional GPIO line used to ping the hardware watchdog function of the MCU
> +    maxItems: 1

Best regards,
Krzysztof