[PATCH v4 1/2] watchdog: dw_wdt: add stop watchdog operation

[PATCH v4 1/2] watchdog: dw_wdt: add stop watchdog operation

[Oleksij Rempel]

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.

At same time WDOG_HW_RUNNING should be remove from dw_wdt_start.
As commented by Guenter Roeck:
dw_wdt sets WDOG_HW_RUNNING in its open function. Result is
that the kref_get() in watchdog_open() won't be executed. But then
kref_put() in close will be called since the watchdog now does stop.
This causes the imbalance.

Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Cc: Wim Van Sebroeck <wim@iguana.be>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: linux-watchdog@vger.kernel.org
---

changes v4:
 - remove WDOG_HW_RUNNING from dw_wdt_start.

changes v3:
 - don't return error if rst is not present and set WDOG_HW_RUNNING bit
   to notify watchdog core.

changes v2:
 - test if dw_wdt->rst is NULL instead of IS_ERR

 drivers/watchdog/dw_wdt.c | 18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)

diff --git a/drivers/watchdog/dw_wdt.c b/drivers/watchdog/dw_wdt.c
index 36be987ff9ef..c2f4ff516230 100644
--- a/drivers/watchdog/dw_wdt.c
+++ b/drivers/watchdog/dw_wdt.c
@@ -127,14 +127,27 @@ static int dw_wdt_start(struct watchdog_device *wdd)
 
 	dw_wdt_set_timeout(wdd, wdd->timeout);
 
-	set_bit(WDOG_HW_RUNNING, &wdd->status);
-
 	writel(WDOG_CONTROL_REG_WDT_EN_MASK,
 	       dw_wdt->regs + WDOG_CONTROL_REG_OFFSET);
 
 	return 0;
 }
 
+static int dw_wdt_stop(struct watchdog_device *wdd)
+{
+	struct dw_wdt *dw_wdt = to_dw_wdt(wdd);
+
+	if (!dw_wdt->rst) {
+		set_bit(WDOG_HW_RUNNING, &wdd->status);
+		return 0;
+	}
+
+	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 +186,7 @@ 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

[PATCH v4 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 v4 1/2] watchdog: dw_wdt: add stop watchdog operation

[Guenter Roeck]

On Tue, Sep 26, 2017 at 08:11:22AM +0200, Oleksij Rempel wrote:
> 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.
> 
> At same time WDOG_HW_RUNNING should be remove from dw_wdt_start.
> As commented by Guenter Roeck:
> dw_wdt sets WDOG_HW_RUNNING in its open function. Result is
> that the kref_get() in watchdog_open() won't be executed. But then
> kref_put() in close will be called since the watchdog now does stop.
> This causes the imbalance.
> 
> Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
> Cc: Wim Van Sebroeck <wim@iguana.be>
> Cc: Guenter Roeck <linux@roeck-us.net>
> Cc: linux-watchdog@vger.kernel.org

Reviewed-by: Guenter Roeck <linux@roeck-us.net>

> ---
> 
> changes v4:
>  - remove WDOG_HW_RUNNING from dw_wdt_start.
> 
> changes v3:
>  - don't return error if rst is not present and set WDOG_HW_RUNNING bit
>    to notify watchdog core.
> 
> changes v2:
>  - test if dw_wdt->rst is NULL instead of IS_ERR
> 
>  drivers/watchdog/dw_wdt.c | 18 ++++++++++++++++--
>  1 file changed, 16 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/watchdog/dw_wdt.c b/drivers/watchdog/dw_wdt.c
> index 36be987ff9ef..c2f4ff516230 100644
> --- a/drivers/watchdog/dw_wdt.c
> +++ b/drivers/watchdog/dw_wdt.c
> @@ -127,14 +127,27 @@ static int dw_wdt_start(struct watchdog_device *wdd)
>  
>  	dw_wdt_set_timeout(wdd, wdd->timeout);
>  
> -	set_bit(WDOG_HW_RUNNING, &wdd->status);
> -
>  	writel(WDOG_CONTROL_REG_WDT_EN_MASK,
>  	       dw_wdt->regs + WDOG_CONTROL_REG_OFFSET);
>  
>  	return 0;
>  }
>  
> +static int dw_wdt_stop(struct watchdog_device *wdd)
> +{
> +	struct dw_wdt *dw_wdt = to_dw_wdt(wdd);
> +
> +	if (!dw_wdt->rst) {
> +		set_bit(WDOG_HW_RUNNING, &wdd->status);
> +		return 0;
> +	}
> +
> +	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 +186,7 @@ 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
>