Re: [PATCH v2 1/2] drivers/watchdog: Add optional ASPEED device tree properties

[Christopher Bostic]

On 6/27/17 4:32 PM, Guenter Roeck wrote:
> On Tue, Jun 27, 2017 at 04:17:33PM -0500, Christopher Bostic wrote:
> > Describe device tree optional properties:
> >
> >    * aspeed,arm-reet - ARM CPU reset on signal
> >    * aspeed,soc-reset - SOC reset on signal
> >    * aspeed,sys-reset - System reset on signal
> >            Disabling system reset may be required in situations where
> >            one of the other watchdog engines in the system is responsible
> >            for this.
> >    * aspeed,interrupt - Interrupt CPU on signal
> >    * aspeed,external-signal - Generate external signal (WDT1 and WDT2 only)
> >    * aspeed,alt-boot - Boot from alternate block on signal
> >
> > Signed-off-by: Christopher Bostic <cbostic@xxxxxxxxxxxxxxxxxx>
> > ---
> > v2 - Add 'aspeed,' prefix to all optional properties
> >     - Add arm-reset, soc-reset, interrupt, alt-boot properties
> > ---
> >   .../devicetree/bindings/watchdog/aspeed-wdt.txt    | 25 ++++++++++++++++++++++
> >   1 file changed, 25 insertions(+)
> >
> > diff --git a/Documentation/devicetree/bindings/watchdog/aspeed-wdt.txt b/Documentation/devicetree/bindings/watchdog/aspeed-wdt.txt
> > index c5e74d7..555b8b4 100644
> > --- a/Documentation/devicetree/bindings/watchdog/aspeed-wdt.txt
> > +++ b/Documentation/devicetree/bindings/watchdog/aspeed-wdt.txt
> > @@ -8,9 +8,34 @@ Required properties:
> >    - reg: physical base address of the controller and length of memory mapped
> >      region
> >   
> > +Optional properties:
> > +   Signal behavior - Whenever a timeout occurs, the watchdog can be programmed
> > +   to generate 6 types of signals:
> > +
> > + - aspeed,arm-reset:  If property is present then reset ARM CPU only.
> > +
> > + - aspeed,soc-reset:  If property is present then reset SOC.
> > +
> > + - aspeed,sys-reset:  If property is present then reset the entire chip.
> > +                      In cases where one of the other watchdog engines
> > +                      in the system is responsible for system reset it
> > +                      may be required to not specify this property.
> > +
> > + - aspeed,interrupt:  If property is present then interrupt CPU.
> > +
> > + - aspeed,external-signal: If property is present then signal is sent to
> > +                           external reset counter (only WDT1 and WDT2).
> > + - aspeed,alt-boot:    If property is present then boot from alternate block.
> > +
> >   Example:
> >   
> >   	wdt1: watchdog@1e785000 {
> >   		compatible = "aspeed,ast2400-wdt";
> >   		reg = <0x1e785000 0x1c>;
> > +		aspeed,arm-reset;
> > +		aspeed,soc-reset;
> > +		aspeed,sys-reset;
> > +		aspeed,interrupt;
> > +		aspeed,external-signal;
> > +		aspeed,alt-boot;
> Is that a bit mask or a value ? I would have thought that,
> for example, a complete system reset would include the SoC reset,
> and a SoC reset would include the ARM reset. Generating an
> interrupt while at the same time resetting the system (or
> part of it) doesn't seem to make much sense either.

No these aren't bitmasks.   The example was intended to indicate what 
could be used.
In practice only a subset of each of these properties would make any 
sense.   How
would you suggest the example be formatted to convey that? Multiple examples
I suppose.

Thanks,
Chris

> Guenter