[PATCH 1/1] riscv: dts: sophgo: enable hardware clock (RTC) on the Milk-V Pioneer

[Chen Wang]

On 1/5/2026 8:01 PM, Michael Orlitzky wrote:
> These boards have a working hardware clock if you put a CR-1220
> battery in them. Let's enable it:
>
> 1. Enable the (already defined) i2c0 by overriding the default
>     status = "disabled" with "okay".
>
> 2. Define the rtc on &i2c0. This is more or less the example from the
>     documentation (devicetree/bindings/rtc/rtc-ds1307.yaml), and it was
>     present in the same form in an earlier 6.1.x vendor kernel.
>
> 3. Copy the pinctrl stuff from &i2c1 and update the PINMUX constants
>     with the IIC0 values from dt-bindings/pinctrl/pinctrl-sg2042.h.
>
> Afterwards, the new I2C and RTC can be enabled with,
>
>    * CONFIG_I2C_DESIGNWARE_CORE=y
>    * CONFIG_I2C_DESIGNWARE_PLATFORM=y
>    * CONFIG_RTC_DRV_DS1307=y
>
> The new I2C should appear under /sys/devices/platform/soc, and with
> any luck you'll have a clock the next time you boot:
>
>    [  T367] rtc-ds1307 5-0068: registered as rtc0
>    [  T367] rtc-ds1307 5-0068: setting system clock to ...
>
> Signed-off-by: Michael Orlitzky <michael at orlitzky.com>
> ---
>   .../boot/dts/sophgo/sg2042-milkv-pioneer.dts  | 21 +++++++++++++++++++
>   1 file changed, 21 insertions(+)
>
> diff --git a/arch/riscv/boot/dts/sophgo/sg2042-milkv-pioneer.dts b/arch/riscv/boot/dts/sophgo/sg2042-milkv-pioneer.dts
> index 54d8386bf9c0..ecf8c1e29079 100644
> --- a/arch/riscv/boot/dts/sophgo/sg2042-milkv-pioneer.dts
> +++ b/arch/riscv/boot/dts/sophgo/sg2042-milkv-pioneer.dts
> @@ -52,6 +52,17 @@ &emmc {
>   	status = "okay";
>   };
>   
> +&i2c0 {
> +	pinctrl-0 = <&i2c0_cfg>;
> +	pinctrl-names = "default";
> +	status = "okay";
> +
> +	rtc: rtc at 68 {
> +		compatible = "dallas,ds1307";
> +		reg = <0x68>;
> +	};
> +};
> +
>   &i2c1 {
>   	pinctrl-0 = <&i2c1_cfg>;
>   	pinctrl-names = "default";
> @@ -89,6 +100,16 @@ sdhci-emmc-rst-pwr-pins {
>   		};
>   	};
>   
> +	i2c0_cfg: i2c0-cfg {
> +		i2c0-pins {
> +			pinmux = <PINMUX(PIN_IIC0_SDA, 0)>,
> +				 <PINMUX(PIN_IIC0_SCL, 0)>;
> +			bias-pull-up;
> +			drive-strength-microamp = <26800>;
> +			input-schmitt-enable;
> +		};
> +	};
> +
>   	i2c1_cfg: i2c1-cfg {
>   		i2c1-pins {
>   			pinmux = <PINMUX(PIN_IIC1_SDA, 0)>,

DTS changes LGTM.

Reviewed-by: Chen Wang <unicorn_wang at outlook.com>

For commit description issues, please refer to Krzysztof's suggestions.

Thanks,

Chen