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

Guenter Roeck
2017-06-27T21:32:28Z

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@linux.vnet.ibm.com>
> ---
> 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.

Guenter