linux-kernel - Re: [PATCH] watchdog: sp805: add restart handler

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Date:   Mon, 30 Apr 2018 04:18:26 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Jongsung Kim <neidhard.kim@....com>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Wim Van Sebroeck <wim@...ana.be>,
        linux-watchdog@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Chanho Min <chanho.min@....com>
Subject: Re: [PATCH] watchdog: sp805: add restart handler

On 04/29/2018 11:44 PM, Jongsung Kim wrote:
> Add restart handler for SP805 watchdog so that the driver can be
> used to reboot the system.
> 
> Signed-off-by: Jongsung Kim <neidhard.kim@....com>
> ---
>   drivers/watchdog/sp805_wdt.c | 19 +++++++++++++++++++
>   1 file changed, 19 insertions(+)
> 
> diff --git a/drivers/watchdog/sp805_wdt.c b/drivers/watchdog/sp805_wdt.c
> index 01d816251302..01f7b6c29f92 100644
> --- a/drivers/watchdog/sp805_wdt.c
> +++ b/drivers/watchdog/sp805_wdt.c
> @@ -23,6 +23,7 @@
>   #include <linux/module.h>
>   #include <linux/moduleparam.h>
>   #include <linux/pm.h>
> +#include <linux/reboot.h>
>   #include <linux/slab.h>
>   #include <linux/spinlock.h>
>   #include <linux/types.h>
> @@ -67,6 +68,7 @@ struct sp805_wdt {
>   	struct clk			*clk;
>   	struct amba_device		*adev;
>   	unsigned int			load_val;
> +	struct notifier_block		restart;
>   };
>   
>   static bool nowayout = WATCHDOG_NOWAYOUT;
> @@ -200,6 +202,18 @@ static const struct watchdog_ops wdt_ops = {
>   	.get_timeleft	= wdt_timeleft,
>   };
>   
> +static int
> +wdt_restart(struct notifier_block *this, unsigned long mode, void *cmd)
> +{
> +	struct sp805_wdt *wdt = container_of(this, struct sp805_wdt, restart);
> +
> +	writel_relaxed(0, wdt->base + WDTCONTROL);
> +	writel_relaxed(0, wdt->base + WDTLOAD);
> +	writel_relaxed(INT_ENABLE | RESET_ENABLE, wdt->base + WDTCONTROL);
> +
> +	return 0;
> +}
> +
>   static int
>   sp805_wdt_probe(struct amba_device *adev, const struct amba_id *id)
>   {
> @@ -241,6 +255,10 @@ sp805_wdt_probe(struct amba_device *adev, const struct amba_id *id)
>   	}
>   	amba_set_drvdata(adev, wdt);
>   
> +	wdt->restart.notifier_call = wdt_restart;
> +	wdt->restart.priority = 128;
> +	register_restart_handler(&wdt->restart);
> +

Why not use the watchdog core ?

Guenter

>   	dev_info(&adev->dev, "registration successful\n");
>   	return 0;
>   
> @@ -253,6 +271,7 @@ static int sp805_wdt_remove(struct amba_device *adev)
>   {
>   	struct sp805_wdt *wdt = amba_get_drvdata(adev);
>   
> +	unregister_restart_handler(&wdt->restart);
>   	watchdog_unregister_device(&wdt->wdd);
>   	watchdog_set_drvdata(&wdt->wdd, NULL);
>   
>