From: Guenter Roeck <linux@roeck-us.net>
To: Ivan Mikhaylov <i.mikhaylov@yadro.com>,
Wim Van Sebroeck <wim@linux-watchdog.org>
Cc: Joel Stanley <joel@jms.id.au>, Andrew Jeffery <andrew@aj.id.au>,
linux-watchdog@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
linux-aspeed@lists.ozlabs.org, linux-kernel@vger.kernel.org,
Alexander Amelkin <a.amelkin@yadro.com>,
openbmc@lists.ozlabs.org, Rob Herring <robh+dt@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
devicetree@vger.kernel.org
Subject: Re: [PATCH v2 3/4] watchdog/aspeed: add support for dual boot
Date: Tue, 27 Aug 2019 06:06:30 -0700 [thread overview]
Message-ID: <d46685d9-c6d2-46af-67aa-844d2b0296a9@roeck-us.net> (raw)
In-Reply-To: <818746d20661b51914a7802dcbe0081352900b05.camel@yadro.com>
On 8/27/19 2:24 AM, Ivan Mikhaylov wrote:
> On Mon, 2019-08-26 at 17:14 -0700, Guenter Roeck wrote:
>>> +/*
>>> + * At alternate side the 'access_cs0' sysfs node provides:
>>> + * ast2400: a way to get access to the primary SPI flash chip at CS0
>>> + * after booting from the alternate chip at CS1.
>>> + * ast2500: a way to restore the normal address mapping from
>>> + * (CS0->CS1, CS1->CS0) to (CS0->CS0, CS1->CS1).
>>> + *
>>> + * Clearing the boot code selection and timeout counter also resets to the
>>> + * initial state the chip select line mapping. When the SoC is in normal
>>> + * mapping state (i.e. booted from CS0), clearing those bits does nothing
>>> for
>>> + * both versions of the SoC. For alternate boot mode (booted from CS1 due
>>> to
>>> + * wdt2 expiration) the behavior differs as described above.
>>> + *
>> The above needs to be in the sysfs attribute documentation as well.
>
> My apologies but I didn't find any suitable, only watchdog parameters with
> dtbindings file, where should I put it? Documentation/watchdog/aspeed-wdt-
> sysfs.rst?
>
Documentation/ABI/testing/sysfs-class-watchdog
Guenter
>>> + * This option can be used with wdt2 (watchdog1) only.
>>
>> This implies a specific watchdog numbering which is not guaranteed.
>> Someone might implement a system with some external watchdog.
>>
>>> + */
>>> +static DEVICE_ATTR_RW(access_cs0);
>>> +
>>> +static struct attribute *bswitch_attrs[] = {
>>> + &dev_attr_access_cs0.attr,
>>> + NULL
>>> +};
>>> +ATTRIBUTE_GROUPS(bswitch);
>>> +
>>> static const struct watchdog_ops aspeed_wdt_ops = {
>>> .start = aspeed_wdt_start,
>>> .stop = aspeed_wdt_stop,
>>> @@ -306,9 +359,16 @@ static int aspeed_wdt_probe(struct platform_device
>>> *pdev)
>>> }
>>>
>>> status = readl(wdt->base + WDT_TIMEOUT_STATUS);
>>> - if (status & WDT_TIMEOUT_STATUS_BOOT_SECONDARY)
>>> + if (status & WDT_TIMEOUT_STATUS_BOOT_SECONDARY) {
>>> wdt->wdd.bootstatus = WDIOF_CARDRESET;
>>>
>>> + if (of_device_is_compatible(np, "aspeed,ast2400-wdt") ||
>>> + of_device_is_compatible(np, "aspeed,ast2500-wdt"))
>>> + wdt->wdd.groups = bswitch_groups;
>
>> Kind of odd that the attribute only exists if the system booted from the
>> second flash, but if that is what you want I won't object. Just make sure
>> that this is explained properly.
> Perhaps dts configuration option would be better solution for it then? "force-
> cs0-switch" as example? Also, if it would be an option, dtbindings/wdt file for
You said earlier that this can not be done automatically but _must_ be done
from user space after the system has booted. Otherwise you could just
automatically switch to cs0 when the driver probes.
As I said, all I am asking for is proper documentation.
Guenter
> documentation will be the right place for it. Usage of this at side 0 will not
> get any good/bad results, it just makes user confused, so I decided to put it
> only at side 1. It works only for ast2400/2500 board unfortunately, for 2600
> there is big difference in switching mechanism. Any other thoughts how to make
> it better?
>
> Thanks.
>
>
next prev parent reply other threads:[~2019-08-27 13:06 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-26 10:46 [PATCH v2 0/4] add dual-boot support Ivan Mikhaylov
2019-08-26 10:46 ` [PATCH v2 1/4] vesnin: add wdt2 section with alt-boot option Ivan Mikhaylov
2019-08-26 10:46 ` [PATCH v2 2/4] vesnin: add secondary SPI flash chip Ivan Mikhaylov
2019-08-26 10:46 ` [PATCH v2 3/4] watchdog/aspeed: add support for dual boot Ivan Mikhaylov
2019-08-27 0:14 ` Guenter Roeck
2019-08-27 9:24 ` Ivan Mikhaylov
2019-08-27 13:06 ` Guenter Roeck [this message]
2019-08-26 10:46 ` [PATCH v2 4/4] dt-bindings/watchdog: Add access_cs0 option for alt-boot Ivan Mikhaylov
2019-08-26 23:57 ` Andrew Jeffery
2019-08-27 0:08 ` Guenter Roeck
2019-08-27 0:11 ` Andrew Jeffery
2019-08-29 22:56 ` Rob Herring
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