diff mbox

[RFC,22/37] watchdog: renesas_wdt: Add restart support

Message ID 1516903391-30467-23-git-send-email-fabrizio.castro@bp.renesas.com (mailing list archive)
State New, archived
Headers show

Commit Message

Fabrizio Castro Jan. 25, 2018, 6:02 p.m. UTC 
This commit extends the driver to add restart support by implementing
the restart callback to trigger the watchdog as quickly as possible.

Signed-off-by: Fabrizio Castro <fabrizio.castro@bp.renesas.com>
Signed-off-by: Ramesh Shanmugasundaram <ramesh.shanmugasundaram@bp.renesas.com>
---
 drivers/watchdog/renesas_wdt.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

Comments

Geert Uytterhoeven Jan. 26, 2018, 10:11 a.m. UTC | #1 
CC Wolfram

On Thu, Jan 25, 2018 at 7:02 PM, Fabrizio Castro
<fabrizio.castro@bp.renesas.com> wrote:
> This commit extends the driver to add restart support by implementing
> the restart callback to trigger the watchdog as quickly as possible.
>
> Signed-off-by: Fabrizio Castro <fabrizio.castro@bp.renesas.com>
> Signed-off-by: Ramesh Shanmugasundaram <ramesh.shanmugasundaram@bp.renesas.com>
> ---
>  drivers/watchdog/renesas_wdt.c | 19 +++++++++++++++++++
>  1 file changed, 19 insertions(+)
>
> diff --git a/drivers/watchdog/renesas_wdt.c b/drivers/watchdog/renesas_wdt.c
> index 831ef83..120ddac 100644
> --- a/drivers/watchdog/renesas_wdt.c
> +++ b/drivers/watchdog/renesas_wdt.c
> @@ -107,6 +107,24 @@ static unsigned int rwdt_get_timeleft(struct watchdog_device *wdev)
>         return DIV_BY_CLKS_PER_SEC(priv, 65536 - val);
>  }
>
> +static int rwdt_restart(struct watchdog_device *wdev, unsigned long action,
> +                       void *data)
> +{
> +       struct rwdt_priv *priv = watchdog_get_drvdata(wdev);
> +
> +       pm_runtime_get_sync(wdev->parent);
> +
> +       rwdt_write(priv, 0x00, RWTCSRB);
> +       rwdt_write(priv, 0x00, RWTCSRA);
> +       rwdt_write(priv, 0xffff, RWTCNT);
> +
> +       while (readb_relaxed(priv->base + RWTCSRA) & RWTCSRA_WRFLG)
> +               cpu_relax();
> +
> +       rwdt_write(priv, 0x80, RWTCSRA);
> +       return 0;
> +}
> +
>  static const struct watchdog_info rwdt_ident = {
>         .options = WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT,
>         .identity = "Renesas WDT Watchdog",
> @@ -118,6 +136,7 @@ static const struct watchdog_ops rwdt_ops = {
>         .stop = rwdt_stop,
>         .ping = rwdt_init_timeout,
>         .get_timeleft = rwdt_get_timeleft,
> +       .restart = rwdt_restart,
>  };
>
>  static int rwdt_probe(struct platform_device *pdev)
> --
> 2.7.4
Guenter Roeck Jan. 26, 2018, 5:14 p.m. UTC | #2 
On Thu, Jan 25, 2018 at 06:02:56PM +0000, Fabrizio Castro wrote:
> This commit extends the driver to add restart support by implementing
> the restart callback to trigger the watchdog as quickly as possible.
> 
> Signed-off-by: Fabrizio Castro <fabrizio.castro@bp.renesas.com>
> Signed-off-by: Ramesh Shanmugasundaram <ramesh.shanmugasundaram@bp.renesas.com>
> ---
>  drivers/watchdog/renesas_wdt.c | 19 +++++++++++++++++++
>  1 file changed, 19 insertions(+)
> 
> diff --git a/drivers/watchdog/renesas_wdt.c b/drivers/watchdog/renesas_wdt.c
> index 831ef83..120ddac 100644
> --- a/drivers/watchdog/renesas_wdt.c
> +++ b/drivers/watchdog/renesas_wdt.c
> @@ -107,6 +107,24 @@ static unsigned int rwdt_get_timeleft(struct watchdog_device *wdev)
>  	return DIV_BY_CLKS_PER_SEC(priv, 65536 - val);
>  }
>  
> +static int rwdt_restart(struct watchdog_device *wdev, unsigned long action,
> +			void *data)
> +{
> +	struct rwdt_priv *priv = watchdog_get_drvdata(wdev);
> +
> +	pm_runtime_get_sync(wdev->parent);
> +
> +	rwdt_write(priv, 0x00, RWTCSRB);
> +	rwdt_write(priv, 0x00, RWTCSRA);
> +	rwdt_write(priv, 0xffff, RWTCNT);
> +
> +	while (readb_relaxed(priv->base + RWTCSRA) & RWTCSRA_WRFLG)
> +		cpu_relax();

Can this get stuck forever or should there be a timeout ?

Guenter

> +
> +	rwdt_write(priv, 0x80, RWTCSRA);
> +	return 0;
> +}
> +
>  static const struct watchdog_info rwdt_ident = {
>  	.options = WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT,
>  	.identity = "Renesas WDT Watchdog",
> @@ -118,6 +136,7 @@ static const struct watchdog_ops rwdt_ops = {
>  	.stop = rwdt_stop,
>  	.ping = rwdt_init_timeout,
>  	.get_timeleft = rwdt_get_timeleft,
> +	.restart = rwdt_restart,
>  };
>  
>  static int rwdt_probe(struct platform_device *pdev)
> -- 
> 2.7.4
> 
> --
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Fabrizio Castro Jan. 26, 2018, 5:50 p.m. UTC | #3 
Hello Guenter,

thank you for your feedback.

> Subject: Re: [RFC 22/37] watchdog: renesas_wdt: Add restart support
>
> On Thu, Jan 25, 2018 at 06:02:56PM +0000, Fabrizio Castro wrote:
> > This commit extends the driver to add restart support by implementing
> > the restart callback to trigger the watchdog as quickly as possible.
> >
> > Signed-off-by: Fabrizio Castro <fabrizio.castro@bp.renesas.com>
> > Signed-off-by: Ramesh Shanmugasundaram <ramesh.shanmugasundaram@bp.renesas.com>
> > ---
> >  drivers/watchdog/renesas_wdt.c | 19 +++++++++++++++++++
> >  1 file changed, 19 insertions(+)
> >
> > diff --git a/drivers/watchdog/renesas_wdt.c b/drivers/watchdog/renesas_wdt.c
> > index 831ef83..120ddac 100644
> > --- a/drivers/watchdog/renesas_wdt.c
> > +++ b/drivers/watchdog/renesas_wdt.c
> > @@ -107,6 +107,24 @@ static unsigned int rwdt_get_timeleft(struct watchdog_device *wdev)
> >  return DIV_BY_CLKS_PER_SEC(priv, 65536 - val);
> >  }
> >
> > +static int rwdt_restart(struct watchdog_device *wdev, unsigned long action,
> > +void *data)
> > +{
> > +struct rwdt_priv *priv = watchdog_get_drvdata(wdev);
> > +
> > +pm_runtime_get_sync(wdev->parent);
> > +
> > +rwdt_write(priv, 0x00, RWTCSRB);
> > +rwdt_write(priv, 0x00, RWTCSRA);
> > +rwdt_write(priv, 0xffff, RWTCNT);
> > +
> > +while (readb_relaxed(priv->base + RWTCSRA) & RWTCSRA_WRFLG)
> > +cpu_relax();
>
> Can this get stuck forever or should there be a timeout ?

This won't get stuck forever, the particular bit we are checking marks the period of time writing to register RWTCNT is prohibited due to synchronization from the previous write. It gets cleared eventually (quite quickly). Also, we use exactly the same logic for the "start" callback.

Best regards,
Fabrizio

>
> Guenter
>
> > +
> > +rwdt_write(priv, 0x80, RWTCSRA);
> > +return 0;
> > +}
> > +
> >  static const struct watchdog_info rwdt_ident = {
> >  .options = WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT,
> >  .identity = "Renesas WDT Watchdog",
> > @@ -118,6 +136,7 @@ static const struct watchdog_ops rwdt_ops = {
> >  .stop = rwdt_stop,
> >  .ping = rwdt_init_timeout,
> >  .get_timeleft = rwdt_get_timeleft,
> > +.restart = rwdt_restart,
> >  };
> >
> >  static int rwdt_probe(struct platform_device *pdev)
> > --
> > 2.7.4
> >
> > --
> > To unsubscribe from this list: send the line "unsubscribe linux-watchdog" in
> > the body of a message to majordomo@vger.kernel.org
> > More majordomo info at  http://vger.kernel.org/majordomo-info.html



Renesas Electronics Europe Ltd, Dukes Meadow, Millboard Road, Bourne End, Buckinghamshire, SL8 5FH, UK. Registered in England & Wales under Registered No. 04586709.
diff mbox

Patch

diff --git a/drivers/watchdog/renesas_wdt.c b/drivers/watchdog/renesas_wdt.c
index 831ef83..120ddac 100644
--- a/drivers/watchdog/renesas_wdt.c
+++ b/drivers/watchdog/renesas_wdt.c
@@ -107,6 +107,24 @@  static unsigned int rwdt_get_timeleft(struct watchdog_device *wdev)
 	return DIV_BY_CLKS_PER_SEC(priv, 65536 - val);
 }
 
+static int rwdt_restart(struct watchdog_device *wdev, unsigned long action,
+			void *data)
+{
+	struct rwdt_priv *priv = watchdog_get_drvdata(wdev);
+
+	pm_runtime_get_sync(wdev->parent);
+
+	rwdt_write(priv, 0x00, RWTCSRB);
+	rwdt_write(priv, 0x00, RWTCSRA);
+	rwdt_write(priv, 0xffff, RWTCNT);
+
+	while (readb_relaxed(priv->base + RWTCSRA) & RWTCSRA_WRFLG)
+		cpu_relax();
+
+	rwdt_write(priv, 0x80, RWTCSRA);
+	return 0;
+}
+
 static const struct watchdog_info rwdt_ident = {
 	.options = WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT,
 	.identity = "Renesas WDT Watchdog",
@@ -118,6 +136,7 @@  static const struct watchdog_ops rwdt_ops = {
 	.stop = rwdt_stop,
 	.ping = rwdt_init_timeout,
 	.get_timeleft = rwdt_get_timeleft,
+	.restart = rwdt_restart,
 };
 
 static int rwdt_probe(struct platform_device *pdev)