[RFC PATCH 1/3] watchdog: s3c2410: add restart notifier

Tomasz Figa
2014-07-08T14:21:09Z

Hi Heiko,

On 06.07.2014 20:42, Heiko St?bner wrote:
> On a lot of Samsung systems the watchdog is responsible for restarting the
> system and until now this code was contained in plat-samsung/watchdog-reset.c .
>
> With the introduction of the restart notifiers, this code can now move into
> driver itself, removing the need for arch-specific code.
>
> Tested on a S3C2442 based GTA02
> Signed-off-by: Heiko Stuebner <heiko@sntech.de>
> ---
> drivers/watchdog/s3c2410_wdt.c | 33 +++++++++++++++++++++++++++++++++
> 1 file changed, 33 insertions(+)
>
> diff --git a/drivers/watchdog/s3c2410_wdt.c b/drivers/watchdog/s3c2410_wdt.c
> index 7c6ccd0..3f89912 100644
> --- a/drivers/watchdog/s3c2410_wdt.c
> +++ b/drivers/watchdog/s3c2410_wdt.c
> @@ -41,6 +41,7 @@
> #include <linux/of.h>
> #include <linux/mfd/syscon.h>
> #include <linux/regmap.h>
> +#include <linux/reboot.h>
>
> #define S3C2410_WTCON 0x00
> #define S3C2410_WTDAT 0x04
> @@ -438,6 +439,31 @@ static inline void s3c2410wdt_cpufreq_deregister(struct s3c2410_wdt *wdt)
> }
> #endif
>
> +static struct s3c2410_wdt *s3c2410wdt_restart_ctx;

This isn't the most elegant way to store context data. Maybe you could
embed the notifier_block struct into s3c2410_wdt struct and then use
container of to retrieve it from s3c2410wdt_restart_notify()?

> +static int s3c2410wdt_restart_notify(struct notifier_block *this,
> + unsigned long mode, void *cmd)
> +{
> + void __iomem *wdt_base = s3c2410wdt_restart_ctx->reg_base;
> +
> + /* disable watchdog, to be safe */
> + writel(0, wdt_base + S3C2410_WTCON);
> +
> + /* put initial values into count and data */
> + writel(0x80, wdt_base + S3C2410_WTCNT);
> + writel(0x80, wdt_base + S3C2410_WTDAT);
> +
> + /* set the watchdog to go and reset... */
> + writel(S3C2410_WTCON_ENABLE | S3C2410_WTCON_DIV16 |
> + S3C2410_WTCON_RSTEN | S3C2410_WTCON_PRESCALE(0x20),
> + wdt_base + S3C2410_WTCON);

I wonder whether you shouldn't wait a bit here for the reset to be
actually triggered.

Best regards,
Tomasz