RE: [PATCH v6 1/6] dt-bindings: usb: add documentation for typec switch simple driver

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Hi Rob

> -----Original Message-----
> From: Jun Li
> Sent: Tuesday, December 1, 2020 11:13 AM
> To: Rob Herring <robh@xxxxxxxxxx>
> Cc: heikki.krogerus@xxxxxxxxxxxxxxx; rafael@xxxxxxxxxx;
> gregkh@xxxxxxxxxxxxxxxxxxx; andriy.shevchenko@xxxxxxxxxxxxxxx;
> hdegoede@xxxxxxxxxx; lee.jones@xxxxxxxxxx;
> mika.westerberg@xxxxxxxxxxxxxxx; dmitry.torokhov@xxxxxxxxx;
> prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx;
> laurent.pinchart+renesas@xxxxxxxxxxxxxxxx; linux-usb@xxxxxxxxxxxxxxx;
> devicetree@xxxxxxxxxxxxxxx; dl-linux-imx <linux-imx@xxxxxxx>; Peter Chen
> <peter.chen@xxxxxxx>
> Subject: RE: [PATCH v6 1/6] dt-bindings: usb: add documentation for typec
> switch simple driver
> 
> 
> 
> > -----Original Message-----
> > From: Rob Herring <robh@xxxxxxxxxx>
> > Sent: Tuesday, December 1, 2020 5:47 AM
> > To: Jun Li <jun.li@xxxxxxx>
> > Cc: heikki.krogerus@xxxxxxxxxxxxxxx; rafael@xxxxxxxxxx;
> > gregkh@xxxxxxxxxxxxxxxxxxx; andriy.shevchenko@xxxxxxxxxxxxxxx;
> > hdegoede@xxxxxxxxxx; lee.jones@xxxxxxxxxx;
> > mika.westerberg@xxxxxxxxxxxxxxx; dmitry.torokhov@xxxxxxxxx;
> > prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx;
> > laurent.pinchart+renesas@xxxxxxxxxxxxxxxx; linux-usb@xxxxxxxxxxxxxxx;
> > devicetree@xxxxxxxxxxxxxxx; dl-linux-imx <linux-imx@xxxxxxx>; Peter
> > Chen <peter.chen@xxxxxxx>
> > Subject: Re: [PATCH v6 1/6] dt-bindings: usb: add documentation for
> > typec switch simple driver
> >
> > On Mon, Nov 23, 2020 at 10:01:31PM +0800, Li Jun wrote:
> > > Some platforms need a simple driver to do some controls according to
> > > typec orientation, this can be extended to be a generic driver with
> > > compatible with "typec-orientation-switch".
> > >
> > > Signed-off-by: Li Jun <jun.li@xxxxxxx>
> > > ---
> > > changes for v6:
> > > - Use general mux bindings for typec switch, one typec switch
> > >   may have 1 or 2 GPIOs for channel selection, if 1 GPIO, only
> > >   can be used to select cc1 or cc2; if 2 GPIOs, the second GPIO
> > >   can be used to deselect both channels or keep normal operations.
> > > - Add one more connection to usb controller.
> > >
> > > No changes for v5.
> > >
> > > changes on v4:
> > > - Use compatible instead of bool property for switch matching.
> > > - Change switch GPIO to be switch simple.
> > > - Change the active channel selection GPIO to be optional.
> > >
> > > previous discussion:
> > >
> >
> https://eur01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fpatch
> > >
> >
> work.ozlabs.org%2Fpatch%2F1054342%2F&amp;data=04%7C01%7Cjun.li%40nxp.c
> > >
> >
> om%7C4436142512ac45fef86f08d8957983c2%7C686ea1d3bc2b4c6fa92cd99c5c3016
> > >
> >
> 35%7C0%7C1%7C637423696442152522%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLj
> > >
> >
> AwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&amp;sdata=
> > > JCV9OtFkfLv4bH2LIxfnk0lVIO6j830%2F%2Bx2OMOi%2Fs6o%3D&amp;reserved=0
> > >
> > >  .../bindings/usb/typec-switch-simple.yaml          | 122
> > +++++++++++++++++++++
> > >  1 file changed, 122 insertions(+)
> > >
> > > diff --git
> > > a/Documentation/devicetree/bindings/usb/typec-switch-simple.yaml
> > > b/Documentation/devicetree/bindings/usb/typec-switch-simple.yaml
> > > new file mode 100644
> > > index 0000000..030ade5
> > > --- /dev/null
> > > +++ b/Documentation/devicetree/bindings/usb/typec-switch-simple.yaml
> > > @@ -0,0 +1,122 @@
> > > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) %YAML 1.2
> > > +---
> > > +$id:
> > >
> >
> +https://eur01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fdevi
> > >
> >
> +cetree.org%2Fschemas%2Fusb%2Ftypec-switch-simple.yaml%23&amp;data=04%
> > >
> >
> +7C01%7Cjun.li%40nxp.com%7C4436142512ac45fef86f08d8957983c2%7C686ea1d3
> > >
> >
> +bc2b4c6fa92cd99c5c301635%7C0%7C1%7C637423696442152522%7CUnknown%7CTWF
> > >
> >
> +pbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6
> > >
> >
> +Mn0%3D%7C3000&amp;sdata=vSLcoGYWCgwpsi4LWbKo2VTyCVgN%2BA7zjHfE8QCS4rg
> > > +%3D&amp;reserved=0
> > > +$schema:
> > >
> >
> +https://eur01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fdevi
> > >
> >
> +cetree.org%2Fmeta-schemas%2Fcore.yaml%23&amp;data=04%7C01%7Cjun.li%40
> > >
> >
> +nxp.com%7C4436142512ac45fef86f08d8957983c2%7C686ea1d3bc2b4c6fa92cd99c
> > >
> >
> +5c301635%7C0%7C1%7C637423696442152522%7CUnknown%7CTWFpbGZsb3d8eyJWIjo
> > >
> >
> +iMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&am
> > >
> >
> +p;sdata=0fd3wjAtKwLCQAY3NG2Be4qNA9FiFhtO0HIZmCK7AQs%3D&amp;reserved=0
> > > +
> > > +title: Typec Orientation Switch Simple Solution Bindings
> > > +
> > > +maintainers:
> > > +  - Li Jun <jun.li@xxxxxxx>
> > > +
> > > +description: |-
> > > +  USB SuperSpeed (SS) lanes routing to which side of typec
> > > +connector is
> > > +  decided by orientation, this maybe achieved by some simple
> > > +control like
> > > +  GPIO toggle.
> > > +
> > > +properties:
> > > +  compatible:
> > > +    const: typec-orientation-switch
> > > +
> > > +  '#mux-control-cells':
> > > +    const: 0
> >
> > Who is the mux-control consumer?
> 
> Typec(controller)
> 
>        ptn5110: tcpc@50 {
>                 compatible = "nxp,ptn5110";
>                 pinctrl-names = "default";
>                 pinctrl-0 = <&pinctrl_typec>;
>                 reg = <0x50>;
>                 interrupt-parent = <&gpio4>;
>                 interrupts = <19 8>;
>                 mux-controls = <&typec_switch>;
>                 mux-control-names = "mux-typec-switch";
> 
>                 usb_con: connector {
>                         compatible = "usb-c-connector";
>                         ... ...
>                         ports {
>                                 #address-cells = <1>;
>                                 #size-cells = <0>;
> 
>                                 port@1 {
>                                         reg = <1>;
>                                         typec_con_ss: endpoint {
>                                                 remote-endpoint =
> <&usb3_orien_sel>;
>                                         };
>                                 };
>                         };
>                 };
>         };
> 
> >
> > > +
> > > +  switch-gpios:
> > > +    description: |
> > > +      GPIO specifiers to select the target channel of mux.
> > > +      The first GPIO is for cc1 and cc2 selection, the GPIO flag use
> > > +      GPIO_ACTIVE_HIGH if GPIO physical state high is for cc1; or use
> > > +      GPIO_ACTIVE_LOW if GPIO physical state low is for cc1.
> > > +      The second gpio is to deselect any channles by places all channels
> > > +      in high-impedance state to reduce current consumption, the
> > > + gpio
> > flag
> > > +      use GPIO_ACTIVE_HIGH if GPIO physical state high is for
> > > +      high-impedance state (so low for normal operations); or Use
> > > +      GPIO_ACTIVE_LOW if GPIO physical state low is for high-impedance
> > > +      state(so high for normal operations).
> > > +    minItems: 1
> > > +    maxItems: 2
> > > +
> > > +  idle-state:
> > > +    description: -|
> > > +      For TYPEC_ORIENTATION_NONE by deselect both channels if supported.
> > > +    const: 2
> > > +
> > > +  # Standard properties described in  #
> > > + Documentation/devicetree/bindings/mux/mux-controller.txt
> > > +
> > > +  port:
> > > +    type: object
> > > +    additionalProperties: false
> > > +    description: -|
> > > +      Connection to the remote endpoint using OF graph bindings that
> model
> > > +      SS data bus to typec connector.
> > > +
> > > +    properties:
> > > +      '#address-cells':
> > > +        const: 1
> > > +
> > > +      '#size-cells':
> > > +        const: 0
> > > +
> > > +      endpoint@0:
> > > +        type: object
> > > +        description: Endpoint connected to typec connector.
> > > +        additionalProperties: false
> > > +
> > > +        properties:
> > > +          reg:
> > > +            const: 0
> > > +          remote-endpoint: true
> > > +
> > > +        required:
> > > +          - remote-endpoint
> > > +
> > > +      endpoint@1:
> > > +        type: object
> > > +        description: Endpoint connected to usb controller.
> > > +        additionalProperties: false
> > > +
> > > +        properties:
> > > +          reg:
> > > +            const: 1
> > > +          remote-endpoint: true
> > > +
> > > +        required:
> > > +          - remote-endpoint
> > > +
> > > +    required:
> > > +      - endpoint@0
> > > +
> > > +required:
> > > +  - compatible
> > > +  - port
> > > +
> > > +additionalProperties: false
> > > +
> > > +examples:
> > > +  - |
> > > +    #include <dt-bindings/gpio/gpio.h>
> > > +    typec_switch: mux-controller {
> > > +        compatible = "typec-orientation-switch";
> > > +        #mux-control-cells = <0>;
> > > +        pinctrl-names = "default";
> > > +        pinctrl-0 = <&pinctrl_ss_sel>;
> > > +        switch-gpios = <&gpio3 15 GPIO_ACTIVE_HIGH>,
> > > +                       <&gpio2 20 GPIO_ACTIVE_HIGH>;
> > > +        idle-state = <2>;
> > > +
> > > +        port {
> > > +                #address-cells = <1>;
> > > +                #size-cells = <0>;
> > > +
> > > +                usb3_orien_sel: endpoint@0 {
> > > +                        reg = <0>;
> > > +                        remote-endpoint = <&typec_con_ss>;
> > > +                };
> > > +
> > > +                usb3_con_data: endpoint@1 {
> > > +                        reg = <1>;
> > > +                        remote-endpoint = <&dwc3_0>;
> > > +                };
> > > +        };
> >
> > This still seems unnecessarily complicated. What I had in mind is just
> > something like this:
> >
> > mux: mux-controller {
> >   compatible = "gpio-mux";
> >   #mux-control-cells = <0>;
> >   mux-gpios = <&gpio3 15 GPIO_ACTIVE_HIGH>,
> >               <&gpio2 20 GPIO_ACTIVE_HIGH>;
> >   idle-state = <2>;
> > };
> >
> > connector {
> >   compatible = "usb-c-connector";
> >   mux-controls = <&mux>;
> >   ...
> > };
> >
> > Then you aren't re-implementing the gpio-mux driver.
> >
> > This should work for *any* mux implementation as long as the mux
> > states always have the same meanings from the perspective of the connector.
> >
> > Of course, I have little visibility into the possible h/w
> > implementations for Type-C and maybe this isn't sufficient. So input
> > from Type-C experts would be helpful.

More thinking of this, I have a proposal like this:

 34         mux: mux-controller {
 33                 compatible = "gpio-mux";
 32                 #mux-control-cells = <0>;
 29                 switch-gpios = <&gpio4 20 GPIO_ACTIVE_LOW>,
 28                                 <&gpio2 20 GPIO_ACTIVE_HIGH>;
 27                 idle-state = <2>;
 26         };
 25

Then I don't need re-implement the gpio-mux driver.

 24         typec_switch {
 23                 compatible = "typec-orientation-switch";
 22                 mux-controls = <&mux>;
 21                 mux-control-names = "mux-typec-switch";
 20
 19                 port {
 18                         usb3_data_ss: endpoint@0 {
 17                                 remote-endpoint = <&typec_con_ss>;
 16                         };
 15                 };
 14         };

The simple typec switch driver as the consumer of mux-control,
and also as the provider of typec_switch to typec class, this
can be extended to use other mux solutions.

 31                 usb_con: connector {
 30                         compatible = "usb-c-connector";
 29                         label = "USB-C";
 20                         ... ...
 19                         ports {
 18                                 #address-cells = <1>;
 17                                 #size-cells = <0>;
 16
 15                                 port@1 {
 14                                         reg = <1>;
 13                                         typec_con_ss: endpoint {
 12                                                 remote-endpoint = <&usb3_data_ss>;
 11                                         };
 10                                 };
  9                         };
  8                 };

Then existing typec mux interface can be kept, is this making sense
to you?

Thanks
Li Jun

> 
> From h/w point view, this can work if only consider my(GPIO) case.
> But I still need register a typec switch in provider side to make it under
> the unified typec switch interface:
> 
>   7 struct typec_switch {
>   6         struct device dev;
>   5         typec_switch_set_fn_t set;
>   4         struct mux_control *mux_ctrl;
>   3 };
> 
> typec_switch->dev.parent = mux_chip->dev;
> 
> So either I put the typec switch creation in exiting mux-gpio driver; or
> I create a new typec switch driver with gpio mux code duplication.
> 
> If I go directly with mux control w/o(out of) typec_switch, then I don't
> need any driver change as you expect, but I guess this is not preferred,
> @Heikki, any comments?
> 
> Thanks
> Li Jun
> 
> >
> > Rob




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