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Date: Thu, 11 Dec 2014 08:04:36 +0100
From: Mike Looijmans <mike.looijmans@...ic.nl>
To: Guenter Roeck <linux@...ck-us.net>
CC: <wim@...ana.be>, <linux-watchdog@...r.kernel.org>,
<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3] gpio_wdt: Add "always_running" feature to GPIO watchdog
Is this v3 patch okay or are you waiting for additional changes?
Kind regards,
Mike.
On 11/21/2014 10:40 AM, Mike Looijmans wrote:
> On some chips, like the TPS386000, the trigger cannot be disabled
> and the CPU must keep toggling the line at all times. Add a switch
> "always_running" to keep toggling the GPIO line regardless of the
> state of the soft part of the watchdog. The "armed" member keeps
> track of whether a timeout must also cause a reset.
>
> Signed-off-by: Mike Looijmans <mike.looijmans@...ic.nl>
> ---
> v3: Indentation adjusted to match
> Fix error path in probe when notification registration fails
> Prevent double assignment of "armed" variable
>
> .../devicetree/bindings/watchdog/gpio-wdt.txt | 5 +++
> drivers/watchdog/gpio_wdt.c | 39 ++++++++++++++++----
> 2 files changed, 36 insertions(+), 8 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/watchdog/gpio-wdt.txt b/Documentation/devicetree/bindings/watchdog/gpio-wdt.txt
> index 37afec1..1987949 100644
> --- a/Documentation/devicetree/bindings/watchdog/gpio-wdt.txt
> +++ b/Documentation/devicetree/bindings/watchdog/gpio-wdt.txt
> @@ -13,6 +13,11 @@ Required Properties:
> by the GPIO flags.
> - hw_margin_ms: Maximum time to reset watchdog circuit (milliseconds).
>
> +Optional Properties:
> +- always-running: If the watchdog timer cannot be disabled, add this flag to
> + have the driver keep toggling the signal without a client. It will only cease
> + to toggle the signal when the device is open and the timeout elapsed.
> +
> Example:
> watchdog: watchdog {
> /* ADM706 */
> diff --git a/drivers/watchdog/gpio_wdt.c b/drivers/watchdog/gpio_wdt.c
> index 220a9e0..9bfbd73 100644
> --- a/drivers/watchdog/gpio_wdt.c
> +++ b/drivers/watchdog/gpio_wdt.c
> @@ -31,6 +31,8 @@ struct gpio_wdt_priv {
> int gpio;
> bool active_low;
> bool state;
> + bool always_running;
> + bool armed;
> unsigned int hw_algo;
> unsigned int hw_margin;
> unsigned long last_jiffies;
> @@ -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 void gpio_wdt_start_impl(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 +60,25 @@ 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);
> +
> + gpio_wdt_start_impl(priv);
> + priv->armed = true;
> +
> + 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->armed = false;
> + if (!priv->always_running) {
> + mod_timer(&priv->timer, 0);
> + gpio_wdt_disable(priv);
> + }
>
> return 0;
> }
> @@ -91,8 +104,8 @@ 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->armed && 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 +210,9 @@ 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_running = of_property_read_bool(pdev->dev.of_node,
> + "always-running");
> +
> watchdog_set_drvdata(&priv->wdd, priv);
>
> priv->wdd.info = &gpio_wdt_ident;
> @@ -216,8 +232,15 @@ 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)
> - watchdog_unregister_device(&priv->wdd);
> + goto error_unregister;
>
> + if (priv->always_running)
> + gpio_wdt_start_impl(priv);
> +
> + return 0;
> +
> +error_unregister:
> + watchdog_unregister_device(&priv->wdd);
> return ret;
> }
>
>
Met vriendelijke groet / kind regards,
Mike Looijmans
System Expert
TOPIC Embedded Systems
Eindhovenseweg 32-C, NL-5683 KH Best
Postbus 440, NL-5680 AK Best
Telefoon: (+31) (0) 499 33 69 79
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E-mail: mike.looijmans@...ic.nl
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