On Thu, Jun 29, 2017 at 08:39:59AM -0500, Christopher Bostic wrote:

On 6/28/17 10:33 PM, Guenter Roeck wrote:

quoted

On 06/28/2017 05:28 PM, Christopher Bostic wrote:

quoted

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 <redacted>
---
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.

quoted

quoted

+            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.

quoted

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.

quoted

   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".

quoted

   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

quoted

There should also be a note explaining that the above are mutually
exclusive.

OK, will add that.

quoted

quoted

+ - 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

quoted

quoted

+ - 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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