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

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Date:   Mon, 22 Jun 2020 09:45:53 +0300
From:   Tero Kristo <t-kristo@...com>
To:     Jan Kiszka <jan.kiszka@...mens.com>, <wim@...ux-watchdog.org>,
        <linux@...ck-us.net>, <linux-watchdog@...r.kernel.org>
CC:     <linux-kernel@...r.kernel.org>, Rob Herring <robh@...nel.org>,
        <devicetree@...r.kernel.org>
Subject: Re: [PATCHv4 1/4] dt-bindings: watchdog: Add support for TI K3 RTI
 watchdog

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@...nel.org>
>> Cc: devicetree@...r.kernel.org
>> Signed-off-by: Tero Kristo <t-kristo@...com>
>> ---
>> 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@...com>
>> +
>> +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@...0000 {
>> +        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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