Add mux controller support for when sdio lines are muxed between a host
and multiple cards.

There are several devices supporting a choice of eMMC or SD on a single
board by both dip switch and gpio, e.g. Renesas RZ/G2L SMARC SoM and
SolidRun RZ/G2L SoM.

In-tree dts for the Renesas boards currently rely on preprocessor macros
to hog gpios and define the card.

By adding mux-states property to sdio controller description, boards can
correctly describe the mux that already exists in hardware - and drivers
can coordinate between mux selection and probing for cards.

Signed-off-by: Josua Mayer <josua@solid-run.com>
---
 Documentation/devicetree/bindings/mmc/renesas,sdhi.yaml | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/Documentation/devicetree/bindings/mmc/renesas,sdhi.yaml b/Documentation/devicetree/bindings/mmc/renesas,sdhi.yaml
index c754ea71f51f7..754ccb1c30efb 100644
--- a/Documentation/devicetree/bindings/mmc/renesas,sdhi.yaml
+++ b/Documentation/devicetree/bindings/mmc/renesas,sdhi.yaml
@@ -106,6 +106,11 @@ properties:
   iommus:
     maxItems: 1
 
+  mux-states:
+    description:
+      mux controller node to route the SDIO signals from SoC to cards.
+    maxItems: 1
+
   power-domains:
     maxItems: 1
 
@@ -275,6 +280,7 @@ examples:
         max-frequency = <195000000>;
         power-domains = <&sysc R8A7790_PD_ALWAYS_ON>;
         resets = <&cpg 314>;
+        mux-states = <&mux 0>;
     };
 
     sdhi1: mmc@ee120000 {

-- 
2.51.0

On Mon, 1 Dec 2025 at 13:31, Josua Mayer <josua@solid-run.com> wrote:
>
> Add mux controller support for when sdio lines are muxed between a host
> and multiple cards.

We have the SD, SDIO, (e)MMC interfaces with their corresponding pins.
Using "sdio lines" becomes confusing as it kind of indicates this is
for "SDIO" only.

>
> There are several devices supporting a choice of eMMC or SD on a single
> board by both dip switch and gpio, e.g. Renesas RZ/G2L SMARC SoM and
> SolidRun RZ/G2L SoM.
>
> In-tree dts for the Renesas boards currently rely on preprocessor macros
> to hog gpios and define the card.
>
> By adding mux-states property to sdio controller description, boards can

Again, please don't use "sdio" here.

> correctly describe the mux that already exists in hardware - and drivers
> can coordinate between mux selection and probing for cards.
>
> Signed-off-by: Josua Mayer <josua@solid-run.com>
> ---
>  Documentation/devicetree/bindings/mmc/renesas,sdhi.yaml | 6 ++++++
>  1 file changed, 6 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/mmc/renesas,sdhi.yaml b/Documentation/devicetree/bindings/mmc/renesas,sdhi.yaml
> index c754ea71f51f7..754ccb1c30efb 100644
> --- a/Documentation/devicetree/bindings/mmc/renesas,sdhi.yaml
> +++ b/Documentation/devicetree/bindings/mmc/renesas,sdhi.yaml
> @@ -106,6 +106,11 @@ properties:
>    iommus:
>      maxItems: 1
>
> +  mux-states:
> +    description:
> +      mux controller node to route the SDIO signals from SoC to cards.

I suggest we change from "SDIO" to "SD/SDIO/eMMC".

> +    maxItems: 1
> +
>    power-domains:
>      maxItems: 1
>
> @@ -275,6 +280,7 @@ examples:
>          max-frequency = <195000000>;
>          power-domains = <&sysc R8A7790_PD_ALWAYS_ON>;
>          resets = <&cpg 314>;
> +        mux-states = <&mux 0>;
>      };
>
>      sdhi1: mmc@ee120000 {
>
> --
> 2.51.0
>
>

Kind regards
Uffe

On Mon, 01 Dec 2025 13:31:10 +0100, Josua Mayer wrote:
> Add mux controller support for when sdio lines are muxed between a host
> and multiple cards.
> 
> There are several devices supporting a choice of eMMC or SD on a single
> board by both dip switch and gpio, e.g. Renesas RZ/G2L SMARC SoM and
> SolidRun RZ/G2L SoM.
> 
> In-tree dts for the Renesas boards currently rely on preprocessor macros
> to hog gpios and define the card.
> 
> By adding mux-states property to sdio controller description, boards can
> correctly describe the mux that already exists in hardware - and drivers
> can coordinate between mux selection and probing for cards.
> 
> Signed-off-by: Josua Mayer <josua@solid-run.com>
> ---
>  Documentation/devicetree/bindings/mmc/renesas,sdhi.yaml | 6 ++++++
>  1 file changed, 6 insertions(+)
> 

Acked-by: Rob Herring (Arm) <robh@kernel.org>