Re: [PATCHv4 1/4] dt-bindings: watchdog: Add support for TI K3 RTI watchdog

[Tero Kristo]

On 18/06/2020 19:09, Jan Kiszka wrote:
> On 12.03.20 10:58, Tero Kristo wrote:
> > TI K3 SoCs contain an RTI (Real Time Interrupt) module which can be
> > used to implement a windowed watchdog functionality. Windowed watchdog
> > will generate an error if it is petted outside the time window, either
> > too early or too late.
> >
> > Cc: Rob Herring <robh@xxxxxxxxxx>
> > Cc: devicetree@xxxxxxxxxxxxxxx
> > Signed-off-by: Tero Kristo <t-kristo@xxxxxx>
> > ---
> > v4:
> >    * changed license to dual
> >    * added documentation for missing properties
> >    * added ref to watchdog.yaml
> >    * renamed main_rti0 to watchdog0 in example
> >
> >   .../bindings/watchdog/ti,rti-wdt.yaml         | 65 +++++++++++++++++++
> >   1 file changed, 65 insertions(+)
> >   create mode 100644 Documentation/devicetree/bindings/watchdog/ti,rti-wdt.yaml
> >
> > diff --git a/Documentation/devicetree/bindings/watchdog/ti,rti-wdt.yaml b/Documentation/devicetree/bindings/watchdog/ti,rti-wdt.yaml
> > new file mode 100644
> > index 000000000000..e83026fef2e9
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/watchdog/ti,rti-wdt.yaml
> > @@ -0,0 +1,65 @@
> > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/watchdog/ti,rti-wdt.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: Texas Instruments K3 SoC Watchdog Timer
> > +
> > +maintainers:
> > +  - Tero Kristo <t-kristo@xxxxxx>
> > +
> > +description:
> > +  The TI K3 SoC watchdog timer is implemented via the RTI (Real Time
> > +  Interrupt) IP module. This timer adds a support for windowed watchdog
> > +  mode, which will signal an error if it is pinged outside the watchdog
> > +  time window, meaning either too early or too late. The error signal
> > +  generated can be routed to either interrupt a safety controller or
> > +  to directly reset the SoC.
> > +
> > +allOf:
> > +  - $ref: "watchdog.yaml#"
> > +
> > +properties:
> > +  compatible:
> > +    enum:
> > +      - ti,j7-rti-wdt
> > +
> > +  reg:
> > +    maxItems: 1
> > +
> > +  clocks:
> > +    maxItems: 1
> > +
> > +  power-domains:
> > +    maxItems: 1
> > +
> > +  assigned-clocks:
> > +    maxItems: 1
> > +
> > +  assigned-clocks-parents:
> > +    maxItems: 1
> > +
> > +required:
> > +  - compatible
> > +  - reg
> > +  - clocks
> > +  - power-domains
> > +
> > +examples:
> > +  - |
> > +    /*
> > +     * RTI WDT in main domain on J721e SoC. Assigned clocks are used to
> > +     * select the source clock for the watchdog, forcing it to tick with
> > +     * a 32kHz clock in this case.
> > +     */
> > +    #include <dt-bindings/soc/ti,sci_pm_domain.h>
> > +
> > +    watchdog0: rti@2200000 {
> > +        compatible = "ti,rti-wdt";
>
> At some stage, you changed the compatible string to something
> J721e-specific. This one wasn't updated.

Hmm nice catch, this should be fixed. I wonder why the DT test tools did 
not catch this when I changed the compatible...

> > +        reg = <0x0 0x2200000 0x0 0x100>;
> > +        clocks = <&k3_clks 252 1>;
> > +        power-domains = <&k3_pds 252 TI_SCI_PD_EXCLUSIVE>;
> > +        assigned-clocks = <&k3_clks 252 1>;
> > +        assigned-clock-parents = <&k3_clks 252 5>;
> > +    };
>
> And where is the binding for the AM65x? I know that PG1 has nice
> erratum, but I would expect PG2 to be fine and register-wise compatible, no?

ti,am65-rti-wdt should be added as a new compatible to this binding once 
we have a board where we can actually support this. Right now TI AM65x 
boards depend on firmware for the ESM side support; there has been some 
internal discussion about how to get this done and I believe you are 
aware of that.

-Tero
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