From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christopher Bostic Subject: Re: [PATCH v2 1/2] drivers/watchdog: Add optional ASPEED device tree properties Date: Wed, 28 Jun 2017 09:55:41 -0500 Message-ID: References: <20170627211734.60477-1-cbostic@linux.vnet.ibm.com> <20170627211734.60477-2-cbostic@linux.vnet.ibm.com> <20170627213216.GA4132@roeck-us.net> <6f2a77e0-e64c-70b7-812a-6a5e8a0b5e6f@linux.vnet.ibm.com> <20170627220740.GA19461@roeck-us.net> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20170627220740.GA19461-0h96xk9xTtrk1uMJSBkQmQ@public.gmane.org> Sender: linux-watchdog-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Guenter Roeck Cc: wim-IQzOog9fTRqzQB+pC5nmwQ@public.gmane.org, robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, mark.rutland-5wv7dgnIgG8@public.gmane.org, joel-U3u1mxZcP9KHXe+LvDLADg@public.gmane.org, linux-watchdog-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: devicetree@vger.kernel.org On 6/27/17 5:07 PM, Guenter Roeck wrote: > On Tue, Jun 27, 2017 at 04:42:24PM -0500, Christopher Bostic wrote: >> >> 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 >>>> --- >>>> 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. >> > I would just pick one (which is perfectly fine). After all, it is an example. > > Reminds me: Is there a default (eg the chip's default configuration) ? > In other words, what is expected to happen if none of the properties > is specified ? Default was to enable SOC reset (parameter aspeed,soc-reset) and system reset (aspeed,sys-reset). Based on your comments in patch v2 2/2 it would be necessary for backwards compatibility to preserve that default behavior. So it seems the optional parameters should be inverted for these: no-soc-reset, no-sys-reset. Thanks, Chris > Thanks, > Guenter > -- To unsubscribe from this list: send the line "unsubscribe linux-watchdog" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html