[PATCH v1 1/2] watchdog: dw_wdt: add stop watchdog operation

[PATCH v1 1/2] watchdog: dw_wdt: add stop watchdog operation

[Oleksij Rempel]

From: Steffen Trumtrar <s.trumtrar-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>

The only way of stopping the watchdog is by resetting it.
Add the watchdog op for stopping the device and reset if
a reset line is provided.

Signed-off-by: Steffen Trumtrar <s.trumtrar-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
Signed-off-by: Oleksij Rempel <o.rempel-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
Cc: Wim Van Sebroeck <wim-IQzOog9fTRqzQB+pC5nmwQ@public.gmane.org>
Cc: Guenter Roeck <linux-0h96xk9xTtrk1uMJSBkQmQ@public.gmane.org>
Cc: linux-watchdog-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
---
 drivers/watchdog/dw_wdt.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/drivers/watchdog/dw_wdt.c b/drivers/watchdog/dw_wdt.c
index 36be987ff9ef..50d8a6a5b5ac 100644
--- a/drivers/watchdog/dw_wdt.c
+++ b/drivers/watchdog/dw_wdt.c
@@ -135,6 +135,21 @@ static int dw_wdt_start(struct watchdog_device *wdd)
 	return 0;
 }
 
+static int dw_wdt_stop(struct watchdog_device *wdd)
+{
+	struct dw_wdt *dw_wdt = to_dw_wdt(wdd);
+
+	if (IS_ERR(dw_wdt->rst)) {
+		dev_warn(wdd->parent, "No reset line. Will not stop.\n");
+		return PTR_ERR(dw_wdt->rst);
+	}
+
+	reset_control_assert(dw_wdt->rst);
+	reset_control_deassert(dw_wdt->rst);
+
+	return 0;
+}
+
 static int dw_wdt_restart(struct watchdog_device *wdd,
 			  unsigned long action, void *data)
 {
@@ -173,6 +188,7 @@ static const struct watchdog_info dw_wdt_ident = {
 static const struct watchdog_ops dw_wdt_ops = {
 	.owner		= THIS_MODULE,
 	.start		= dw_wdt_start,
+	.stop		= dw_wdt_stop,
 	.ping		= dw_wdt_ping,
 	.set_timeout	= dw_wdt_set_timeout,
 	.get_timeleft	= dw_wdt_get_timeleft,
-- 
2.11.0

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[PATCH v1 2/2] ARM: socfpga: dtsi: add dw-wdt reset lines

[Oleksij Rempel]

From: Steffen Trumtrar <s.trumtrar@pengutronix.de>

Signed-off-by: Steffen Trumtrar <s.trumtrar@pengutronix.de>
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Cc: Dinh Nguyen <dinguyen@opensource.altera.com>
Cc: linux-arm-kernel@lists.infradead.org
---
 arch/arm/boot/dts/socfpga.dtsi | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/arm/boot/dts/socfpga.dtsi b/arch/arm/boot/dts/socfpga.dtsi
index 7e24dc8e82d4..6e49cee084b8 100644
--- a/arch/arm/boot/dts/socfpga.dtsi
+++ b/arch/arm/boot/dts/socfpga.dtsi
@@ -924,6 +924,7 @@
 			reg = <0xffd02000 0x1000>;
 			interrupts = <0 171 4>;
 			clocks = <&osc1>;
+			resets = <&rst L4WD0_RESET>;
 			status = "disabled";
 		};
 
@@ -932,6 +933,7 @@
 			reg = <0xffd03000 0x1000>;
 			interrupts = <0 172 4>;
 			clocks = <&osc1>;
+			resets = <&rst L4WD1_RESET>;
 			status = "disabled";
 		};
 	};
-- 
2.11.0

Re: [PATCH v1 1/2] watchdog: dw_wdt: add stop watchdog operation

[Philipp Zabel]

Hi Oleksij,

On Thu, 2017-09-14 at 10:14 +0200, Oleksij Rempel wrote:
> From: Steffen Trumtrar <s.trumtrar-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
> 
> The only way of stopping the watchdog is by resetting it.
> Add the watchdog op for stopping the device and reset if
> a reset line is provided.
> 
> Signed-off-by: Steffen Trumtrar <s.trumtrar-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
> Signed-off-by: Oleksij Rempel <o.rempel-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
> Cc: Wim Van Sebroeck <wim-IQzOog9fTRqzQB+pC5nmwQ@public.gmane.org>
> Cc: Guenter Roeck <linux-0h96xk9xTtrk1uMJSBkQmQ@public.gmane.org>
> Cc: linux-watchdog-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
> ---
>  drivers/watchdog/dw_wdt.c | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
> 
> diff --git a/drivers/watchdog/dw_wdt.c b/drivers/watchdog/dw_wdt.c
> index 36be987ff9ef..50d8a6a5b5ac 100644
> --- a/drivers/watchdog/dw_wdt.c
> +++ b/drivers/watchdog/dw_wdt.c
> @@ -135,6 +135,21 @@ static int dw_wdt_start(struct watchdog_device
> *wdd)
>  	return 0;
>  }
>  
> +static int dw_wdt_stop(struct watchdog_device *wdd)
> +{
> +	struct dw_wdt *dw_wdt = to_dw_wdt(wdd);
> +
> +	if (IS_ERR(dw_wdt->rst)) {

	if (!dw_wdt->rst) {

Since commit 65a3b6935d92 ("watchdog: dw_wdt: get reset lines from dt"),
the reset control is requested as optional, meaning dw_wdt->rst == NULL
if the reset line is not present. If an error is value is stored into
dw_wdt->rst, the probe function does not succeed.

> +		dev_warn(wdd->parent, "No reset line. Will not
> stop.\n");
> +		return PTR_ERR(dw_wdt->rst);
> +	}

regards
Philipp
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Re: [PATCH v1 1/2] watchdog: dw_wdt: add stop watchdog operation

[Guenter Roeck]

On Thu, Sep 14, 2017 at 10:14:01AM +0200, Oleksij Rempel wrote:
> From: Steffen Trumtrar <s.trumtrar-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
> 
> The only way of stopping the watchdog is by resetting it.
> Add the watchdog op for stopping the device and reset if
> a reset line is provided.
> 
> Signed-off-by: Steffen Trumtrar <s.trumtrar-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
> Signed-off-by: Oleksij Rempel <o.rempel-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
> Cc: Wim Van Sebroeck <wim-IQzOog9fTRqzQB+pC5nmwQ@public.gmane.org>
> Cc: Guenter Roeck <linux-0h96xk9xTtrk1uMJSBkQmQ@public.gmane.org>
> Cc: linux-watchdog-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
> ---
>  drivers/watchdog/dw_wdt.c | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
> 
> diff --git a/drivers/watchdog/dw_wdt.c b/drivers/watchdog/dw_wdt.c
> index 36be987ff9ef..50d8a6a5b5ac 100644
> --- a/drivers/watchdog/dw_wdt.c
> +++ b/drivers/watchdog/dw_wdt.c
> @@ -135,6 +135,21 @@ static int dw_wdt_start(struct watchdog_device *wdd)
>  	return 0;
>  }
>  
> +static int dw_wdt_stop(struct watchdog_device *wdd)
> +{
> +	struct dw_wdt *dw_wdt = to_dw_wdt(wdd);
> +
> +	if (IS_ERR(dw_wdt->rst)) {
> +		dev_warn(wdd->parent, "No reset line. Will not stop.\n");
> +		return PTR_ERR(dw_wdt->rst);
> +	}

This is a change in behavior. Previously, with no stop function,
the watchdog core would keep pinging the watchdog in this situation.
Now it would end up spitting a warning and resetting the system.

> +
> +	reset_control_assert(dw_wdt->rst);
> +	reset_control_deassert(dw_wdt->rst);
> +
> +	return 0;
> +}
> +
>  static int dw_wdt_restart(struct watchdog_device *wdd,
>  			  unsigned long action, void *data)
>  {
> @@ -173,6 +188,7 @@ static const struct watchdog_info dw_wdt_ident = {
>  static const struct watchdog_ops dw_wdt_ops = {
>  	.owner		= THIS_MODULE,
>  	.start		= dw_wdt_start,
> +	.stop		= dw_wdt_stop,
>  	.ping		= dw_wdt_ping,
>  	.set_timeout	= dw_wdt_set_timeout,
>  	.get_timeleft	= dw_wdt_get_timeleft,
> -- 
> 2.11.0
> 
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