[PATCH v4 1/3] dt-bindings: clk: vc5: Add properties for configuring the SD/OE pin

[PATCH v4 1/3] dt-bindings: clk: vc5: Add properties for configuring the SD/OE pin

[Sean Anderson]

These properties allow configuring the SD/OE pin as described in the
datasheet.

Signed-off-by: Sean Anderson <sean.anderson@seco.com>
---

Changes in v4:
- Specify that bindings should specify these properties, but don't make
  any guarantees about the driver's behavior when they are not present.
- Clarify description of idt,(en|dis)able-shutdown properties.
- Make opposing properties mutually exclusive.
- Add these properties to the example.

Changes in v3:
- Add idt,disable-shutdown and idt,output-enable-active-low to allow for
  a default of not changing the SP/SH bits at all.

Changes in v2:
- Rename idt,sd-active-high to idt,output-enable-active-high
- Add idt,enable-shutdown

 .../bindings/clock/idt,versaclock5.yaml       | 63 +++++++++++++++++++
 1 file changed, 63 insertions(+)

diff --git a/Documentation/devicetree/bindings/clock/idt,versaclock5.yaml b/Documentation/devicetree/bindings/clock/idt,versaclock5.yaml
index 28675b0b80f1..2631a175612b 100644
--- a/Documentation/devicetree/bindings/clock/idt,versaclock5.yaml
+++ b/Documentation/devicetree/bindings/clock/idt,versaclock5.yaml
@@ -30,6 +30,21 @@ description: |
     3 -- OUT3
     4 -- OUT4
 
+  The idt,(en|dis)able-shutdown and idt,output-enable-active-(high|low)
+  properties control the SH (en_global_shutdown) and SP bits of the
+  Primary Source and Shutdown Register, respectively. Their behavior is
+  summarized by the following table:
+
+  SH SP Output when the SD/OE pin is Low/High
+  == == =====================================
+   0  0 Active/Inactive
+   0  1 Inactive/Active
+   1  0 Active/Shutdown
+   1  1 Inactive/Shutdown
+
+  One of idt,(en|dis)able-shutdown and one of
+  idt,output-enable-active-(high|low) should be specified.
+
 maintainers:
   - Luca Ceresoli <luca@lucaceresoli.net>
 
@@ -64,6 +79,34 @@ properties:
     maximum: 22760
     description: Optional load capacitor for XTAL1 and XTAL2
 
+  idt,enable-shutdown:
+    $ref: /schemas/types.yaml#/definitions/flag
+    description: |
+      Enable the shutdown functionality. The chip will be shut down if
+      the SD/OE pin is driven high. This corresponds to setting the SH
+      bit of the Primary Source and Shutdown Register.
+
+  idt,disable-shutdown:
+    $ref: /schemas/types.yaml#/definitions/flag
+    description: |
+      Disable the shutdown functionality. The chip will never be shut
+      down based on the value of the SD/OE pin. This corresponds to
+      clearing the SH bit of the Primary Source and Shutdown Register.
+
+  idt,output-enable-active-high:
+    $ref: /schemas/types.yaml#/definitions/flag
+    description: |
+      This enables output when the SD/OE pin is high, and disables
+      output when the SD/OE pin is low. This corresponds to setting the
+      SP bit of the Primary Source and Shutdown Register.
+
+  idt,output-enable-active-low:
+    $ref: /schemas/types.yaml#/definitions/flag
+    description: |
+      This disables output when the SD/OE pin is high, and enables
+      output when the SD/OE pin is low. This corresponds to clearing the
+      SP bit of the Primary Source and Shutdown Register.
+
 patternProperties:
   "^OUT[1-4]$":
     type: object
@@ -109,6 +152,22 @@ allOf:
       required:
         - clock-names
         - clocks
+  - if:
+      true
+    then:
+      oneOf:
+        - required:
+            - idt,enable-shutdown
+        - required:
+            - idt,disable-shutdown
+  - if:
+      true
+    then:
+      oneOf:
+        - required:
+            - idt,output-enable-active-high
+        - required:
+            - idt,output-enable-active-low
 
 additionalProperties: false
 
@@ -138,6 +197,10 @@ examples:
             clocks = <&ref25m>;
             clock-names = "xin";
 
+            /* Set the SD/OE pin's settings */
+            idt,disable-shutdown;
+            idt,output-enable-active-low;
+
             OUT1 {
                 idt,drive-mode = <VC5_CMOSD>;
                 idt,voltage-microvolts = <1800000>;
-- 
2.25.1

Re: [PATCH v4 1/3] dt-bindings: clk: vc5: Add properties for configuring the SD/OE pin

[Geert Uytterhoeven]

Hi Sean,

On Thu, Jul 1, 2021 at 8:20 PM Sean Anderson <sean.anderson@seco.com> wrote:
> These properties allow configuring the SD/OE pin as described in the
> datasheet.
>
> Signed-off-by: Sean Anderson <sean.anderson@seco.com>
> ---
>
> Changes in v4:
> - Specify that bindings should specify these properties, but don't make
>   any guarantees about the driver's behavior when they are not present.
> - Clarify description of idt,(en|dis)able-shutdown properties.
> - Make opposing properties mutually exclusive.
> - Add these properties to the example.

Thanks for the update!

> --- a/Documentation/devicetree/bindings/clock/idt,versaclock5.yaml
> +++ b/Documentation/devicetree/bindings/clock/idt,versaclock5.yaml

> @@ -109,6 +152,22 @@ allOf:
>        required:
>          - clock-names
>          - clocks
> +  - if:
> +      true
> +    then:
> +      oneOf:
> +        - required:
> +            - idt,enable-shutdown
> +        - required:
> +            - idt,disable-shutdown
> +  - if:
> +      true
> +    then:
> +      oneOf:
> +        - required:
> +            - idt,output-enable-active-high
> +        - required:
> +            - idt,output-enable-active-low

Do you really need the "if: true then:"?
Just the "oneOf: ..." worked fine for me in another binding, but then I
didn't have a surrounding "allOf" to interfere...

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

Re: [PATCH v4 1/3] dt-bindings: clk: vc5: Add properties for configuring the SD/OE pin

[Luca Ceresoli]

Hi Sean,

On 01/07/21 20:20, Sean Anderson wrote:
> These properties allow configuring the SD/OE pin as described in the
> datasheet.
> 
> Signed-off-by: Sean Anderson <sean.anderson@seco.com>
> ---
> 
> Changes in v4:
> - Specify that bindings should specify these properties, but don't make
>   any guarantees about the driver's behavior when they are not present.
> - Clarify description of idt,(en|dis)able-shutdown properties.
> - Make opposing properties mutually exclusive.
> - Add these properties to the example.
> 
> Changes in v3:
> - Add idt,disable-shutdown and idt,output-enable-active-low to allow for
>   a default of not changing the SP/SH bits at all.
> 
> Changes in v2:
> - Rename idt,sd-active-high to idt,output-enable-active-high
> - Add idt,enable-shutdown
> 
>  .../bindings/clock/idt,versaclock5.yaml       | 63 +++++++++++++++++++
>  1 file changed, 63 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/clock/idt,versaclock5.yaml b/Documentation/devicetree/bindings/clock/idt,versaclock5.yaml
> index 28675b0b80f1..2631a175612b 100644
> --- a/Documentation/devicetree/bindings/clock/idt,versaclock5.yaml
> +++ b/Documentation/devicetree/bindings/clock/idt,versaclock5.yaml
> @@ -30,6 +30,21 @@ description: |
>      3 -- OUT3
>      4 -- OUT4
>  
> +  The idt,(en|dis)able-shutdown and idt,output-enable-active-(high|low)
> +  properties control the SH (en_global_shutdown) and SP bits of the
> +  Primary Source and Shutdown Register, respectively. Their behavior is
> +  summarized by the following table:
> +
> +  SH SP Output when the SD/OE pin is Low/High
> +  == == =====================================
> +   0  0 Active/Inactive
> +   0  1 Inactive/Active
> +   1  0 Active/Shutdown
> +   1  1 Inactive/Shutdown

I just got an update from Renesas support, which confirms our table as
far as possible:

> I find that SH will only work when the Polarity bit is set to Active Low (SP=0).  When I program SP=1 together with SH=1, the outputs are always off. It simply won’t work.  So the Shutdown function can only be used with Active Low polarity for the SD/OE pin.  There is a pull-down resistor on the chip so when the pin is left open, outputs will be enabled with Active Low polarity.
>  
> [...] What is a more accurate description is that you can only use the Shutdown function (SH=1) together with the Active Low polarity (SP=0) setting.  The combination of SH=1 and SP=1 is an ‘illegal’ combination.
>  
> We actually find that very few customers use the Shutdown function. It is only partly useful because it turns off more circuits than the Output Enable function but there is still significant power consumption in Shutdown. The general expectation of a Shutdown function is that the power consumption will go down to a few microamperes of leakage current when in Shutdown but this device will not do that.

The combination SH=1 and SP=1 is not well specified, so I can't confirm
whether it should be Inactive/Shutdown or Shutdown/Shutdown or whatever.
Also I would not define the SH=1 and SP=1 combination as "illegal" but
rather as "useless".

Definitely (and obviously) the outputs are never driven when SH=1 and
SP=1. So I think we can stick to your table and I think this patch is
fine, more details are not needed in the DT bindings IMO. The only open
point now is the remark by Geert about the 'if: true' construct.

-- 
Luca

Re: [PATCH v4 1/3] dt-bindings: clk: vc5: Add properties for configuring the SD/OE pin

[Sean Anderson]

On 7/2/21 3:14 AM, Geert Uytterhoeven wrote:
 > Hi Sean,
 >
 > On Thu, Jul 1, 2021 at 8:20 PM Sean Anderson <sean.anderson@seco.com> wrote:
 >> These properties allow configuring the SD/OE pin as described in the
 >> datasheet.
 >>
 >> Signed-off-by: Sean Anderson <sean.anderson@seco.com>
 >> ---
 >>
 >> Changes in v4:
 >> - Specify that bindings should specify these properties, but don't make
 >>   any guarantees about the driver's behavior when they are not present.
 >> - Clarify description of idt,(en|dis)able-shutdown properties.
 >> - Make opposing properties mutually exclusive.
 >> - Add these properties to the example.
 >
 > Thanks for the update!
 >
 >> --- a/Documentation/devicetree/bindings/clock/idt,versaclock5.yaml
 >> +++ b/Documentation/devicetree/bindings/clock/idt,versaclock5.yaml
 >
 >> @@ -109,6 +152,22 @@ allOf:
 >>        required:
 >>          - clock-names
 >>          - clocks
 >> +  - if:
 >> +      true
 >> +    then:
 >> +      oneOf:
 >> +        - required:
 >> +            - idt,enable-shutdown
 >> +        - required:
 >> +            - idt,disable-shutdown
 >> +  - if:
 >> +      true
 >> +    then:
 >> +      oneOf:
 >> +        - required:
 >> +            - idt,output-enable-active-high
 >> +        - required:
 >> +            - idt,output-enable-active-low
 >
 > Do you really need the "if: true then:"?
 > Just the "oneOf: ..." worked fine for me in another binding, but then I
 > didn't have a surrounding "allOf" to interfere...

Yes. If you want to have multiple oneOfs, they have to go under an
allOf. And allOf *only* allows if statements. This is a pretty big
deficiency, IMO, but not something I can address here.

--Sean

Re: [PATCH v4 1/3] dt-bindings: clk: vc5: Add properties for configuring the SD/OE pin

[Rob Herring]

On Fri, Jul 02, 2021 at 11:07:57AM -0400, Sean Anderson wrote:
> 
> 
> On 7/2/21 3:14 AM, Geert Uytterhoeven wrote:
> > Hi Sean,
> >
> > On Thu, Jul 1, 2021 at 8:20 PM Sean Anderson <sean.anderson@seco.com> wrote:
> >> These properties allow configuring the SD/OE pin as described in the
> >> datasheet.
> >>
> >> Signed-off-by: Sean Anderson <sean.anderson@seco.com>
> >> ---
> >>
> >> Changes in v4:
> >> - Specify that bindings should specify these properties, but don't make
> >>   any guarantees about the driver's behavior when they are not present.
> >> - Clarify description of idt,(en|dis)able-shutdown properties.
> >> - Make opposing properties mutually exclusive.
> >> - Add these properties to the example.
> >
> > Thanks for the update!
> >
> >> --- a/Documentation/devicetree/bindings/clock/idt,versaclock5.yaml
> >> +++ b/Documentation/devicetree/bindings/clock/idt,versaclock5.yaml
> >
> >> @@ -109,6 +152,22 @@ allOf:
> >>        required:
> >>          - clock-names
> >>          - clocks
> >> +  - if:
> >> +      true
> >> +    then:
> >> +      oneOf:
> >> +        - required:
> >> +            - idt,enable-shutdown
> >> +        - required:
> >> +            - idt,disable-shutdown
> >> +  - if:
> >> +      true
> >> +    then:
> >> +      oneOf:
> >> +        - required:
> >> +            - idt,output-enable-active-high
> >> +        - required:
> >> +            - idt,output-enable-active-low
> >
> > Do you really need the "if: true then:"?
> > Just the "oneOf: ..." worked fine for me in another binding, but then I
> > didn't have a surrounding "allOf" to interfere...
> 
> Yes. If you want to have multiple oneOfs, they have to go under an
> allOf. And allOf *only* allows if statements. This is a pretty big
> deficiency, IMO, but not something I can address here.

Humm, we should relax that, not work around it.

Rob

Re: [PATCH v4 1/3] dt-bindings: clk: vc5: Add properties for configuring the SD/OE pin

[Rob Herring]

On Fri, Jul 2, 2021 at 9:18 AM Rob Herring <robh@kernel.org> wrote:
>
> On Fri, Jul 02, 2021 at 11:07:57AM -0400, Sean Anderson wrote:
> >
> >
> > On 7/2/21 3:14 AM, Geert Uytterhoeven wrote:
> > > Hi Sean,
> > >
> > > On Thu, Jul 1, 2021 at 8:20 PM Sean Anderson <sean.anderson@seco.com> wrote:
> > >> These properties allow configuring the SD/OE pin as described in the
> > >> datasheet.
> > >>
> > >> Signed-off-by: Sean Anderson <sean.anderson@seco.com>
> > >> ---
> > >>
> > >> Changes in v4:
> > >> - Specify that bindings should specify these properties, but don't make
> > >>   any guarantees about the driver's behavior when they are not present.
> > >> - Clarify description of idt,(en|dis)able-shutdown properties.
> > >> - Make opposing properties mutually exclusive.
> > >> - Add these properties to the example.
> > >
> > > Thanks for the update!
> > >
> > >> --- a/Documentation/devicetree/bindings/clock/idt,versaclock5.yaml
> > >> +++ b/Documentation/devicetree/bindings/clock/idt,versaclock5.yaml
> > >
> > >> @@ -109,6 +152,22 @@ allOf:
> > >>        required:
> > >>          - clock-names
> > >>          - clocks
> > >> +  - if:
> > >> +      true
> > >> +    then:
> > >> +      oneOf:
> > >> +        - required:
> > >> +            - idt,enable-shutdown
> > >> +        - required:
> > >> +            - idt,disable-shutdown
> > >> +  - if:
> > >> +      true
> > >> +    then:
> > >> +      oneOf:
> > >> +        - required:
> > >> +            - idt,output-enable-active-high
> > >> +        - required:
> > >> +            - idt,output-enable-active-low
> > >
> > > Do you really need the "if: true then:"?
> > > Just the "oneOf: ..." worked fine for me in another binding, but then I
> > > didn't have a surrounding "allOf" to interfere...
> >
> > Yes. If you want to have multiple oneOfs, they have to go under an
> > allOf. And allOf *only* allows if statements. This is a pretty big
> > deficiency, IMO, but not something I can address here.
>
> Humm, we should relax that, not work around it.

I've now relaxed this restriction in dt-schema master.

Rob

P.S. I probably broke something because it's Friday afternoon before
going on holiday for a week (so I'll do a tagged release when back).

Re: [PATCH v4 1/3] dt-bindings: clk: vc5: Add properties for configuring the SD/OE pin

[Sean Anderson]

On 7/2/21 5:15 PM, Rob Herring wrote:
> On Fri, Jul 2, 2021 at 9:18 AM Rob Herring <robh@kernel.org> wrote:
>>
>> On Fri, Jul 02, 2021 at 11:07:57AM -0400, Sean Anderson wrote:
>> >
>> >
>> > On 7/2/21 3:14 AM, Geert Uytterhoeven wrote:
>> > > Hi Sean,
>> > >
>> > > On Thu, Jul 1, 2021 at 8:20 PM Sean Anderson <sean.anderson@seco.com> wrote:
>> > >> These properties allow configuring the SD/OE pin as described in the
>> > >> datasheet.
>> > >>
>> > >> Signed-off-by: Sean Anderson <sean.anderson@seco.com>
>> > >> ---
>> > >>
>> > >> Changes in v4:
>> > >> - Specify that bindings should specify these properties, but don't make
>> > >>   any guarantees about the driver's behavior when they are not present.
>> > >> - Clarify description of idt,(en|dis)able-shutdown properties.
>> > >> - Make opposing properties mutually exclusive.
>> > >> - Add these properties to the example.
>> > >
>> > > Thanks for the update!
>> > >
>> > >> --- a/Documentation/devicetree/bindings/clock/idt,versaclock5.yaml
>> > >> +++ b/Documentation/devicetree/bindings/clock/idt,versaclock5.yaml
>> > >
>> > >> @@ -109,6 +152,22 @@ allOf:
>> > >>        required:
>> > >>          - clock-names
>> > >>          - clocks
>> > >> +  - if:
>> > >> +      true
>> > >> +    then:
>> > >> +      oneOf:
>> > >> +        - required:
>> > >> +            - idt,enable-shutdown
>> > >> +        - required:
>> > >> +            - idt,disable-shutdown
>> > >> +  - if:
>> > >> +      true
>> > >> +    then:
>> > >> +      oneOf:
>> > >> +        - required:
>> > >> +            - idt,output-enable-active-high
>> > >> +        - required:
>> > >> +            - idt,output-enable-active-low
>> > >
>> > > Do you really need the "if: true then:"?
>> > > Just the "oneOf: ..." worked fine for me in another binding, but then I
>> > > didn't have a surrounding "allOf" to interfere...
>> >
>> > Yes. If you want to have multiple oneOfs, they have to go under an
>> > allOf. And allOf *only* allows if statements. This is a pretty big
>> > deficiency, IMO, but not something I can address here.
>>
>> Humm, we should relax that, not work around it.
> 
> I've now relaxed this restriction in dt-schema master.
> 
> Rob
> 
> P.S. I probably broke something because it's Friday afternoon before
> going on holiday for a week (so I'll do a tagged release when back).

Will you be doing a release? I'm waiting on that before I send v5.

--Sean