On Thu, Jun 29, 2017 at 08:39:59AM -0500, Christopher Bostic wrote:
>
>
> On 6/28/17 10:33 PM, Guenter Roeck wrote:
> >On 06/28/2017 05:28 PM, Christopher Bostic wrote:
> >>Describe device tree optional properties:
> >>
> >> * aspeed,arm-reet - ARM CPU reset on signal
> >> * aspeed,no-soc-reset - SOC reset on signal
> >> * aspeed,no-sys-reset - System reset on signal
> >> * 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>
> >>---
> >>v3 - Invert soc and sys reset to 'no' to preserve backwards
> >> compatibility. SOC and SYS reset will be set by default
> >> without any optional parameters set
> >>v2 - Add 'aspeed,' prefix to all optional properties
> >> - Add arm-reset, soc-reset, interrupt, alt-boot properties
> >>---
> >> .../devicetree/bindings/watchdog/aspeed-wdt.txt | 24
> >>++++++++++++++++++++++
> >> 1 file changed, 24 insertions(+)
> >>
> >>diff --git a/Documentation/devicetree/bindings/watchdog/aspeed-wdt.txt
> >>b/Documentation/devicetree/bindings/watchdog/aspeed-wdt.txt
> >>index c5e74d7..6f18005 100644
> >>--- a/Documentation/devicetree/bindings/watchdog/aspeed-wdt.txt
> >>+++ b/Documentation/devicetree/bindings/watchdog/aspeed-wdt.txt
> >>@@ -8,9 +8,33 @@ 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/not generate 6 types of signals:
> >>+
> >>+ - aspeed,arm-reset: If property is present then reset ARM CPU only.
> >>+ If not specified no ARM CPU reset is done.
> >>+
> >>+ - aspeed,no-soc-reset: If property is present then do not reset SOC.
> >>+ If not specified then SOC reset is done.
> >>+
> >>+ - aspeed,no-sys-reset: If property is present then do not reset
> >>system.
> >>+ Typcally used in tandem with 'aspeed-external-signal'
> >
> >Is this correct ? As I understand the datasheet, it could also used in
> >tandem with
> >aspeed,interrupt.
> True, that should be documented. Will add that.
> >
> >>+ If not specified then system reset is done.
> >>+
> >
> >I'll leave it up to Rob to decide, but for my part I don't understand
> >no-soc-reset.
> As the aspeed watchdog driver exists prior to this change an SOC reset is
> done by
> default. In order to preserve backwards compatibility a missing optional
> property
> should result in default behavior. I however need to be able to specify
> that SOC
> reset be disabled in some way. This goes back to our discussion about why
> we'd
> ever want to disable SYSTEM reset in the first place. Same reasoning
> applies for
> SOC reset.
>
> >I would instead use four properties.
> >
> > aspeed,arm-reset
> > aspeed,soc-reset
> Per my response above I think it should remain as aspeed,no-soc-reset due to
> backwards compatibility requirements.
The same can be accomplished with "aspeed,no-reset", which would avoid the, in
my opinion, awkward "no-{sys,soc}-reset" poperties.
> > aspeed,sys-reset (which is the default)
> Again as per our discussion yesterday I need some way to specify how system
> reset is to be done. For backwards compatibility, a lack of parameter here
> would
> result in a system reset being configured. Only way to indicate to the
> driver
> that no system reset is to be done is to indicate 'no' system reset in the
> optional
> parameter.
Or "aspeed,no-reset".
> > aspeed,no-reset
> This parameter seems ambiguous as we could be doing a 'no system reset'
> or a 'no SOC reset' in theory.
{arm,soc,sys}-reset are mutually exclusive per datasheet, and there is a
separate configuration bit which enables the reset in the first place.
I don't see how that is ambiguous.
Anyway, I don't think we are making any progress here. Let's wait for
guidance from Rob.
Guenter
> >
> >There should also be a note explaining that the above are mutually
> >exclusive.
> >
> OK, will add that.
>
> >>+ - aspeed,interrupt: If property is present then interrupt CPU.
> >>+ If not specified then don't interrupt CPU.
> >>+
> >>+ - aspeed,external-signal: If property is present then signal is sent
> >>to
> >>+ external reset counter (only WDT1 and WDT2). If not
> >>+ specified no external signal is sent.
> >
> >For consistency, either add an empty line here or remove the empty lines
> >above
>
> Will fix.
>
> Thanks,
> Chris
> >
> >>+ - aspeed,alt-boot: If property is present then boot from alternate
> >>block.
> >>+
> >> Example:
> >> wdt1: watchdog@1e785000 {
> >> compatible = "aspeed,ast2400-wdt";
> >> reg = <0x1e785000 0x1c>;
> >>+ aspeed,no-sys-reset;
> >>+ aspeed,external-signal;
> >> };
> >>
> >
>
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