Messages in this thread | | | Date | Sun, 07 Sep 2014 10:23:49 -0700 | From | Guenter Roeck <> | Subject | Re: [PATCH v2] Add support for always enabled watchdog timers to gpio_wdt driver |
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On 09/06/2014 09:47 AM, Evgeny Boger wrote: > From: Evgeny Boger <boger@contactless.ru> > > Add option to use with watchdog timers which are always enabled > in hardware, i.e. there is no way to enable/disable it via GPIO pin. > The driver will start pinging WDT immediately upon loading > and will continue to do so even after stopping the watchdog. > > Signed-off-by: Evgeny Boger <boger@contactless.ru> > --- >
Overall looks good to me, though we really need feedback from the DT folks on the binding. There is a parallel effort to add this functionality into the watchdog core, meaning the proposed binding "'always-enabled' will very likely find its way into other drivers. We'll also need a separate binding to express "watchdog can not be stopped after started once". That is a separate issue, but important to keep in mind when discussing the bindings.
Thanks, Guenter
> Changes since v1: > * fixed typos and indentation > * gpio_wdt_start_timer renamed to gpio_wdt_start_hwping. > This function actually starts the timer to ping hardware. > I personally find both proposed gpio_wdt_enable and __gpio_wdt_start > names discouraging in this context. > * fixed broken error handling for register_reboot_notifier > > .../devicetree/bindings/watchdog/gpio-wdt.txt | 14 ++++++- > drivers/watchdog/gpio_wdt.c | 46 +++++++++++++++++----- > 2 files changed, 50 insertions(+), 10 deletions(-) > > diff --git a/Documentation/devicetree/bindings/watchdog/gpio-wdt.txt b/Documentation/devicetree/bindings/watchdog/gpio-wdt.txt > index 37afec1..047fe3f 100644 > --- a/Documentation/devicetree/bindings/watchdog/gpio-wdt.txt > +++ b/Documentation/devicetree/bindings/watchdog/gpio-wdt.txt > @@ -12,8 +12,11 @@ Required Properties: > the opposite level disables the WDT. Active level is determined > by the GPIO flags. > - hw_margin_ms: Maximum time to reset watchdog circuit (milliseconds). > +- always-enabled: Use with watchdog timer which is always enabled > + in hardware, i.e. there is no way to enable/disable it via GPIO pin. > + Driver will start pinging WDT immediately upon loading. > > -Example: > +Examples: > watchdog: watchdog { > /* ADM706 */ > compatible = "linux,wdt-gpio"; > @@ -21,3 +24,12 @@ Example: > hw_algo = "toggle"; > hw_margin_ms = <1600>; > }; > + > + watchdog: watchdog { > + /* TPS3813 */ > + compatible = "linux,wdt-gpio"; > + gpios = <&gpio3 9 GPIO_ACTIVE_LOW>; > + hw_algo = "toggle"; > + hw_margin_ms = <10000>; > + always-enabled; > + }; > diff --git a/drivers/watchdog/gpio_wdt.c b/drivers/watchdog/gpio_wdt.c > index 220a9e0..b6ab6e7 100644 > --- a/drivers/watchdog/gpio_wdt.c > +++ b/drivers/watchdog/gpio_wdt.c > @@ -37,6 +37,8 @@ struct gpio_wdt_priv { > struct notifier_block notifier; > struct timer_list timer; > struct watchdog_device wdd; > + bool always_enabled; > + bool started; > }; > > static void gpio_wdt_disable(struct gpio_wdt_priv *priv) > @@ -48,10 +50,8 @@ static void gpio_wdt_disable(struct gpio_wdt_priv *priv) > gpio_direction_input(priv->gpio); > } > > -static int gpio_wdt_start(struct watchdog_device *wdd) > +static int gpio_wdt_start_hwping(struct gpio_wdt_priv *priv) > { > - struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd); > - > priv->state = priv->active_low; > gpio_direction_output(priv->gpio, priv->state); > priv->last_jiffies = jiffies; > @@ -60,12 +60,30 @@ static int gpio_wdt_start(struct watchdog_device *wdd) > return 0; > } > > +static int gpio_wdt_start(struct watchdog_device *wdd) > +{ > + struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd); > + > + priv->started = true; > + if (priv->always_enabled) { > + /* hardware ping timer is already enabled */ > + priv->last_jiffies = jiffies; > + } else { > + gpio_wdt_start_hwping(priv); > + } > + > + return 0; > +} > + > static int gpio_wdt_stop(struct watchdog_device *wdd) > { > struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd); > > - mod_timer(&priv->timer, 0); > - gpio_wdt_disable(priv); > + priv->started = false; > + if (!priv->always_enabled) { > + mod_timer(&priv->timer, 0); > + gpio_wdt_disable(priv); > + } > > return 0; > } > @@ -91,8 +109,9 @@ static void gpio_wdt_hwping(unsigned long data) > struct watchdog_device *wdd = (struct watchdog_device *)data; > struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd); > > - if (time_after(jiffies, priv->last_jiffies + > - msecs_to_jiffies(wdd->timeout * 1000))) { > + if (priv->started && > + time_after(jiffies, priv->last_jiffies + > + msecs_to_jiffies(wdd->timeout * 1000))) { > dev_crit(wdd->dev, "Timer expired. System will reboot soon!\n"); > return; > } > @@ -197,6 +216,9 @@ static int gpio_wdt_probe(struct platform_device *pdev) > /* Use safe value (1/2 of real timeout) */ > priv->hw_margin = msecs_to_jiffies(hw_margin / 2); > > + priv->always_enabled = of_property_read_bool(pdev->dev.of_node, > + "always-enabled"); > + > watchdog_set_drvdata(&priv->wdd, priv); > > priv->wdd.info = &gpio_wdt_ident; > @@ -207,6 +229,7 @@ static int gpio_wdt_probe(struct platform_device *pdev) > if (watchdog_init_timeout(&priv->wdd, 0, &pdev->dev) < 0) > priv->wdd.timeout = SOFT_TIMEOUT_DEF; > > + priv->started = false; > setup_timer(&priv->timer, gpio_wdt_hwping, (unsigned long)&priv->wdd); > > ret = watchdog_register_device(&priv->wdd); > @@ -215,10 +238,15 @@ static int gpio_wdt_probe(struct platform_device *pdev) > > priv->notifier.notifier_call = gpio_wdt_notify_sys; > ret = register_reboot_notifier(&priv->notifier); > - if (ret) > + if (ret) { > watchdog_unregister_device(&priv->wdd); > + return ret; > + } > > - return ret; > + if (priv->always_enabled) > + gpio_wdt_start_hwping(priv); > + > + return 0; > } > > static int gpio_wdt_remove(struct platform_device *pdev) >
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