[PATCH 3/4] mfd: Add support for UGREEN NASync DH2300 MCU

[Lee Jones]

On Fri, 12 Jun 2026, Alexey Charkov wrote:

> Add a driver for the HC32F005 MCU used as an embedded controller on the
> UGREEN NASync DH2300 NAS.
> 
> This part provides the shared I2C regmap to be used by function-specific
> sub-devices, and instantiates the SATA drive-bay power gate regulator.
> Implemented as an MFD to allow for other functions of the MCU to be added
> later: vendor binaries imply that it also provides a hardware watchdog
> and somehow serves as a wake source, but so far only the SATA power gating
> function has been confirmed in absence of documentation and sources for the
> vendor firmware.
> 
> Signed-off-by: Alexey Charkov <alchark at flipper.net>
> ---
>  MAINTAINERS                     |  1 +
>  drivers/mfd/Kconfig             | 16 +++++++++++
>  drivers/mfd/Makefile            |  1 +
>  drivers/mfd/ugreen-dh2300-mcu.c | 60 +++++++++++++++++++++++++++++++++++++++++
>  4 files changed, 78 insertions(+)

Did you see: drivers/mfd/simple-mfd-i2c.c ?

> diff --git a/MAINTAINERS b/MAINTAINERS
> index ca27df7cd684..9578a06fe651 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -27637,6 +27637,7 @@ UGREEN DH2300 MCU MFD DRIVER
>  M:	Alexey Charkov <alchark at flipper.net>
>  S:	Maintained
>  F:	Documentation/devicetree/bindings/mfd/ugreen,dh2300-mcu.yaml
> +F:	drivers/mfd/ugreen-dh2300-mcu.c
>  
>  UHID USERSPACE HID IO DRIVER
>  M:	David Rheinsberg <david at readahead.eu>
> diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
> index 763ce6a34782..5a2ad75bd9c9 100644
> --- a/drivers/mfd/Kconfig
> +++ b/drivers/mfd/Kconfig
> @@ -1947,6 +1947,22 @@ config MFD_TPS6594_SPI
>  	  This driver can also be built as a module.  If so, the module
>  	  will be called tps6594-spi.
>  
> +config MFD_UGREEN_DH2300_MCU
> +	tristate "UGREEN NASync DH2300 embedded controller"
> +	depends on I2C
> +	depends on OF
> +	select MFD_CORE
> +	select REGMAP_I2C
> +	help
> +	  Say yes here to enable support for the HC32F005 microcontroller found
> +	  on the UGREEN NASync DH2300 NAS, where it acts as a board embedded
> +	  controller. This core driver sets up the shared register map and
> +	  instantiates the function sub-devices (the SATA drive-bay power
> +	  regulator).
> +
> +	  This driver can also be built as a module. If so, the module will be
> +	  called ugreen-dh2300-mcu.
> +
>  config TWL4030_CORE
>  	bool "TI TWL4030/TWL5030/TWL6030/TPS659x0 Support"
>  	depends on I2C=y
> diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
> index dd4bb7e77c33..6247239bcfe1 100644
> --- a/drivers/mfd/Makefile
> +++ b/drivers/mfd/Makefile
> @@ -109,6 +109,7 @@ obj-$(CONFIG_MFD_TPS65912_SPI)  += tps65912-spi.o
>  obj-$(CONFIG_MFD_TPS6594)	+= tps6594-core.o
>  obj-$(CONFIG_MFD_TPS6594_I2C)	+= tps6594-i2c.o
>  obj-$(CONFIG_MFD_TPS6594_SPI)	+= tps6594-spi.o
> +obj-$(CONFIG_MFD_UGREEN_DH2300_MCU)	+= ugreen-dh2300-mcu.o
>  obj-$(CONFIG_MENELAUS)		+= menelaus.o
>  
>  obj-$(CONFIG_TWL4030_CORE)	+= twl-core.o twl4030-irq.o twl6030-irq.o
> diff --git a/drivers/mfd/ugreen-dh2300-mcu.c b/drivers/mfd/ugreen-dh2300-mcu.c
> new file mode 100644
> index 000000000000..5184b0c98759
> --- /dev/null
> +++ b/drivers/mfd/ugreen-dh2300-mcu.c
> @@ -0,0 +1,60 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Core driver for the UGREEN NASync DH2300 embedded controller (HC32F005 MCU).
> + *
> + * The microcontroller sits on I2C and exposes an 8-bit register map. It is a
> + * multi-function device: SATA drive-bay power gate, hardware watchdog and
> + * possibly other functions
> + */
> +
> +#include <linux/i2c.h>
> +#include <linux/mfd/core.h>
> +#include <linux/mod_devicetable.h>
> +#include <linux/module.h>
> +#include <linux/regmap.h>
> +
> +#define UGREEN_DH2300_MCU_REG_MAX	0x94
> +
> +static const struct regmap_config ugreen_dh2300_mcu_regmap_config = {
> +	.reg_bits = 8,
> +	.val_bits = 8,
> +	.max_register = UGREEN_DH2300_MCU_REG_MAX,
> +};
> +
> +static const struct mfd_cell ugreen_dh2300_mcu_cells[] = {
> +	{ .name = "ugreen-dh2300-mcu-regulator" },
> +};
> +
> +static int ugreen_dh2300_mcu_probe(struct i2c_client *client)
> +{
> +	struct device *dev = &client->dev;
> +	struct regmap *regmap;
> +
> +	regmap = devm_regmap_init_i2c(client, &ugreen_dh2300_mcu_regmap_config);
> +	if (IS_ERR(regmap))
> +		return dev_err_probe(dev, PTR_ERR(regmap),
> +				     "failed to initialise regmap\n");
> +
> +	return devm_mfd_add_devices(dev, PLATFORM_DEVID_AUTO,
> +				    ugreen_dh2300_mcu_cells,
> +				    ARRAY_SIZE(ugreen_dh2300_mcu_cells),
> +				    NULL, 0, NULL);
> +}
> +
> +static const struct of_device_id ugreen_dh2300_mcu_of_match[] = {
> +	{ .compatible = "ugreen,dh2300-mcu" },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(of, ugreen_dh2300_mcu_of_match);
> +
> +static struct i2c_driver ugreen_dh2300_mcu_driver = {
> +	.driver = {
> +		.name = "ugreen-dh2300-mcu",
> +		.of_match_table = ugreen_dh2300_mcu_of_match,
> +	},
> +	.probe = ugreen_dh2300_mcu_probe,
> +};
> +module_i2c_driver(ugreen_dh2300_mcu_driver);
> +
> +MODULE_DESCRIPTION("UGREEN NASync DH2300 embedded controller core driver");
> +MODULE_LICENSE("GPL");
> 
> -- 
> 2.53.0
> 

-- 
Lee Jones