Add mux controller support for when the I2C lines are muxed after
signals come out of SoC and before they go to any client.

Signed-off-by: Jayesh Choudhary <j-choudhary@ti.com>
---
 Documentation/devicetree/bindings/i2c/ti,omap4-i2c.yaml | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/Documentation/devicetree/bindings/i2c/ti,omap4-i2c.yaml b/Documentation/devicetree/bindings/i2c/ti,omap4-i2c.yaml
index 8c2e35fabf5b..58d32ceeacfc 100644
--- a/Documentation/devicetree/bindings/i2c/ti,omap4-i2c.yaml
+++ b/Documentation/devicetree/bindings/i2c/ti,omap4-i2c.yaml
@@ -47,6 +47,11 @@ properties:
     $ref: /schemas/types.yaml#/definitions/string
     deprecated: true
 
+  mux-states:
+    description:
+      mux controller node to route the I2C signals from SoC to clients.
+    maxItems: 1
+
 required:
   - compatible
   - reg
@@ -87,4 +92,5 @@ examples:
         interrupts = <GIC_SPI 200 IRQ_TYPE_LEVEL_HIGH>;
         #address-cells = <1>;
         #size-cells = <0>;
+        mux-states = <&i2c_mux 1>;
     };
-- 
2.34.1

On Tue, Mar 18, 2025 at 5:36 AM Jayesh Choudhary <j-choudhary@ti.com> wrote:
>
> Add mux controller support for when the I2C lines are muxed after
> signals come out of SoC and before they go to any client.
>
> Signed-off-by: Jayesh Choudhary <j-choudhary@ti.com>
> ---
>  Documentation/devicetree/bindings/i2c/ti,omap4-i2c.yaml | 6 ++++++
>  1 file changed, 6 insertions(+)

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

Hi Jayesh,

Am 18.03.25 um 11:36 schrieb Jayesh Choudhary:
> Add mux controller support for when the I2C lines are muxed after
> signals come out of SoC and before they go to any client.
> 
> Signed-off-by: Jayesh Choudhary <j-choudhary@ti.com>
> ---
>   Documentation/devicetree/bindings/i2c/ti,omap4-i2c.yaml | 6 ++++++
>   1 file changed, 6 insertions(+)

Is there any chance for this to be generic across any i2c controller
regardless of SoC in use?
Is this perhaps also generic to any device in dts,
similar to assigned-clocks?

E.g. in k3-am642-hummingboard-t-{pcie,usb3}.dts we have a mux on the 
carrier board switching a serdes lane between two different connectors.
It would make sense for pcie and usb phy nodes to delay probe in a 
similar fashion.
The same may hold true for other buses muxed at boot-time or based on 
assembly options or extension cards.

sincerely
Josua Mayer

On Tue, Mar 18, 2025 at 2:55 PM Ing. Josua Mayer <josua.mayer@jm0.eu> wrote:
>
> Hi Jayesh,
>
> Am 18.03.25 um 11:36 schrieb Jayesh Choudhary:
> > Add mux controller support for when the I2C lines are muxed after
> > signals come out of SoC and before they go to any client.
> >
> > Signed-off-by: Jayesh Choudhary <j-choudhary@ti.com>
> > ---
> >   Documentation/devicetree/bindings/i2c/ti,omap4-i2c.yaml | 6 ++++++
> >   1 file changed, 6 insertions(+)
>
> Is there any chance for this to be generic across any i2c controller
> regardless of SoC in use?
> Is this perhaps also generic to any device in dts,
> similar to assigned-clocks?

$ git grep assigned-clocks arch/ | wc -l
2097

>
> E.g. in k3-am642-hummingboard-t-{pcie,usb3}.dts we have a mux on the
> carrier board switching a serdes lane between two different connectors.
> It would make sense for pcie and usb phy nodes to delay probe in a
> similar fashion.
> The same may hold true for other buses muxed at boot-time or based on
> assembly options or extension cards.

$ git grep mux-states arch/
arch/arm64/boot/dts/ti/k3-j7200-common-proc-board.dts:
mux-states = <&mux0 1>;
arch/arm64/boot/dts/ti/k3-j721s2-common-proc-board.dts:
mux-states = <&mux0 1>;
arch/arm64/boot/dts/ti/k3-j721s2-common-proc-board.dts:
mux-states = <&mux1 1>;
arch/arm64/boot/dts/ti/k3-j784s4-j742s2-evm-common.dtsi:
 mux-states = <&mux1 1>;

I'm not convinced it is common enough to allow everywhere.

Rob

Am Tue, 18 Mar 2025 17:18:29 -0500
schrieb Rob Herring <robh@kernel.org>:

> On Tue, Mar 18, 2025 at 2:55 PM Ing. Josua Mayer <josua.mayer@jm0.eu> wrote:
> >
> > Hi Jayesh,
> >
> > Am 18.03.25 um 11:36 schrieb Jayesh Choudhary:  
> > > Add mux controller support for when the I2C lines are muxed after
> > > signals come out of SoC and before they go to any client.
> > >
> > > Signed-off-by: Jayesh Choudhary <j-choudhary@ti.com>
> > > ---
> > >   Documentation/devicetree/bindings/i2c/ti,omap4-i2c.yaml | 6 ++++++
> > >   1 file changed, 6 insertions(+)  
> >
> > Is there any chance for this to be generic across any i2c controller
> > regardless of SoC in use?
> > Is this perhaps also generic to any device in dts,
> > similar to assigned-clocks?  
> 
> $ git grep assigned-clocks arch/ | wc -l
> 2097
> 
> >
> > E.g. in k3-am642-hummingboard-t-{pcie,usb3}.dts we have a mux on the
> > carrier board switching a serdes lane between two different connectors.
> > It would make sense for pcie and usb phy nodes to delay probe in a
> > similar fashion.
> > The same may hold true for other buses muxed at boot-time or based on
> > assembly options or extension cards.  
> 
> $ git grep mux-states arch/
> arch/arm64/boot/dts/ti/k3-j7200-common-proc-board.dts:
> mux-states = <&mux0 1>;
> arch/arm64/boot/dts/ti/k3-j721s2-common-proc-board.dts:
> mux-states = <&mux0 1>;
> arch/arm64/boot/dts/ti/k3-j721s2-common-proc-board.dts:
> mux-states = <&mux1 1>;
> arch/arm64/boot/dts/ti/k3-j784s4-j742s2-evm-common.dtsi:
>  mux-states = <&mux1 1>;
> 
> I'm not convinced it is common enough to allow everywhere.
> 
strange logic. It is not in there, because it is not allowed/supported
and some quirk maybe is added elsewhere, e.g. in bootloader or private
kernel branch.
So you cannot say whether such a case is common engough by looking what
is *now* in the dtb.

Regards,
Andreas