linux-kernel - Re: [RFC PATCH 1/5] watchdog: Add API to trigger reboots

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Message-ID: <20140502100105.GC17370@arm.com>
Date:	Fri, 2 May 2014 11:01:05 +0100
From:	Will Deacon <will.deacon@....com>
To:	Guenter Roeck <linux@...ck-us.net>
Cc:	"linux-watchdog@...r.kernel.org" <linux-watchdog@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	Wim Van Sebroeck <wim@...ana.be>,
	Catalin Marinas <Catalin.Marinas@....com>,
	Maxime Ripard <maxime.ripard@...e-electrons.com>,
	Arnd Bergmann <arnd@...db.de>,
	Russell King <linux@....linux.org.uk>,
	Jonas Jensen <jonas.jensen@...il.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH 1/5] watchdog: Add API to trigger reboots

Hi Guenter,

This looks pretty sensible to me (and the arm/arm64 bits look fine too), but
I have one question below...

On Thu, May 01, 2014 at 04:41:29PM +0100, Guenter Roeck wrote:
> Some hardware implements reboot through its watchdog hardware,
> for example by triggering a watchdog timeout. Platform specific
> code starts to spread into watchdog drivers, typically by setting
> pointers to a callback functions which is then called from the
> platform reset handler.
> 
> To simplify code and provide a unified API to trigger reboots by
> watchdog drivers, provide a single API to trigger such reboots
> through the watchdog subsystem.
> 
> Signed-off-by: Guenter Roeck <linux@...ck-us.net>
> ---
>  drivers/watchdog/watchdog_core.c |   17 +++++++++++++++++
>  include/linux/watchdog.h         |   11 +++++++++++
>  2 files changed, 28 insertions(+)
> 
> diff --git a/drivers/watchdog/watchdog_core.c b/drivers/watchdog/watchdog_core.c
> index cec9b55..4ec6e2f 100644
> --- a/drivers/watchdog/watchdog_core.c
> +++ b/drivers/watchdog/watchdog_core.c
> @@ -43,6 +43,17 @@
>  static DEFINE_IDA(watchdog_ida);
>  static struct class *watchdog_class;
>  
> +static struct watchdog_device *wdd_reboot_dev;
> +
> +void watchdog_do_reboot(enum reboot_mode mode, const char *cmd)
> +{
> +	if (wdd_reboot_dev) {
> +		if (wdd_reboot_dev->ops->reboot)
> +			wdd_reboot_dev->ops->reboot(wdd_reboot_dev, mode, cmd);
> +	}
> +}

What reboot_mode values would you expect a watchdog to support other than
REBOOT_HARD? Also, is the cmd even useful here?

Will
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