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Re: [PATCH 1/2] drivers/watchdog: Document new aspeed optional dev tree properties.

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  Re: [PATCH 1/2] drivers/watchdog: Document new aspeed optional dev  tree properties. Joel Stanley <joel@jms.id.au> - 2017-06-27 05:10 +0200
    Re: [PATCH 1/2] drivers/watchdog: Document new aspeed optional dev  tree properties. Christopher Bostic <cbostic@linux.vnet.ibm.com> - 2017-06-27 21:50 +0200

#1675262 — Re: [PATCH 1/2] drivers/watchdog: Document new aspeed optional dev tree properties.

On Wed, Jun 14, 2017 at 6:08 AM, Christopher Bostic
<cbostic@linux.vnet.ibm.com> wrote:
> Describe new optional property 'external-signal'.  When present in the
> system device tree an exernal signal is generated on watchdog timeout.
>
> Describe new optional property 'no-system-reset'.  When present in the
> system device tree no system reset is to occur on watchdog timeout.
> System reset in this case is managed by one of the other watchogs
> available.
>
> Signed-off-by: Christopher Bostic <cbostic@linux.vnet.ibm.com>
> ---
>  Documentation/devicetree/bindings/watchdog/aspeed-wdt.txt | 11 +++++++++++
>  1 file changed, 11 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/watchdog/aspeed-wdt.txt b/Documentation/devicetree/bindings/watchdog/aspeed-wdt.txt
> index c5e74d7..4099ea5 100644
> --- a/Documentation/devicetree/bindings/watchdog/aspeed-wdt.txt
> +++ b/Documentation/devicetree/bindings/watchdog/aspeed-wdt.txt
> @@ -8,9 +8,20 @@ Required properties:
>   - reg: physical base address of the controller and length of memory mapped
>     region
>
> +Optional properties:
> + - external-signal: If the property is present then an external signal is to
> +   be generated on watchdog timeout.  If absent, external signal is not
> +   generated.
> +
> + - no-system-reset: If the property is present then system will not be reset
> +   on watchdog timeout. In this case one of the other watchdogs will handle
> +   reset.  If absent then the watchdog resets the system on timeout.

I'm not sure that this describes the hardware. The datasheet says:

Whenever timeout ocurs, WDT can program to generate 6 types of signals:

 * ARM reset signal: to reset ARM CPU only
 * SOC reset signal: to reset SOC part function
 * System reset signal: to reset full chip
 * Interrupt signal: to interrupt CPU
 * Eternal signal: to external reset counter (only WDT1 and WDT2)
 * Alternate boot signal: to boot from alternate block

I think your bindings should describe these modes where possible.

Cheers,

Joel


> +
>  Example:
>
>         wdt1: watchdog@1e785000 {
>                 compatible = "aspeed,ast2400-wdt";
>                 reg = <0x1e785000 0x1c>;
> +               external-signal;
> +               no-system-reset;
>         };
> --
> 1.8.2.2
>

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#1676116

On 6/26/17 9:59 PM, Joel Stanley wrote:
> On Wed, Jun 14, 2017 at 6:08 AM, Christopher Bostic
> <cbostic@linux.vnet.ibm.com> wrote:
>> Describe new optional property 'external-signal'.  When present in the
>> system device tree an exernal signal is generated on watchdog timeout.
>>
>> Describe new optional property 'no-system-reset'.  When present in the
>> system device tree no system reset is to occur on watchdog timeout.
>> System reset in this case is managed by one of the other watchogs
>> available.
>>
>> Signed-off-by: Christopher Bostic <cbostic@linux.vnet.ibm.com>
>> ---
>>   Documentation/devicetree/bindings/watchdog/aspeed-wdt.txt | 11 +++++++++++
>>   1 file changed, 11 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/watchdog/aspeed-wdt.txt b/Documentation/devicetree/bindings/watchdog/aspeed-wdt.txt
>> index c5e74d7..4099ea5 100644
>> --- a/Documentation/devicetree/bindings/watchdog/aspeed-wdt.txt
>> +++ b/Documentation/devicetree/bindings/watchdog/aspeed-wdt.txt
>> @@ -8,9 +8,20 @@ Required properties:
>>    - reg: physical base address of the controller and length of memory mapped
>>      region
>>
>> +Optional properties:
>> + - external-signal: If the property is present then an external signal is to
>> +   be generated on watchdog timeout.  If absent, external signal is not
>> +   generated.
>> +
>> + - no-system-reset: If the property is present then system will not be reset
>> +   on watchdog timeout. In this case one of the other watchdogs will handle
>> +   reset.  If absent then the watchdog resets the system on timeout.
> I'm not sure that this describes the hardware. The datasheet says:
>
> Whenever timeout ocurs, WDT can program to generate 6 types of signals:
>
>   * ARM reset signal: to reset ARM CPU only
>   * SOC reset signal: to reset SOC part function
>   * System reset signal: to reset full chip
>   * Interrupt signal: to interrupt CPU
>   * Eternal signal: to external reset counter (only WDT1 and WDT2)
>   * Alternate boot signal: to boot from alternate block
>
> I think your bindings should describe these modes where possible.

I'll add the modes you describe.

Thanks,
Chris
>
> Cheers,
>
> Joel
>
>
>> +
>>   Example:
>>
>>          wdt1: watchdog@1e785000 {
>>                  compatible = "aspeed,ast2400-wdt";
>>                  reg = <0x1e785000 0x1c>;
>> +               external-signal;
>> +               no-system-reset;
>>          };
>> --
>> 1.8.2.2
>>

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