On 11/20/2014 10:53 PM, 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@xxxxxxxx> --- v2: Rename property "always_running" to "always-running" and add devicetree documentation .../devicetree/bindings/watchdog/gpio-wdt.txt | 5 +++++ drivers/watchdog/gpio_wdt.c | 20 +++++++++++++++++--- 2 files changed, 22 insertions(+), 3 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..3266215 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;
Please align columns with the other variables.
unsigned int hw_algo; unsigned int hw_margin; unsigned long last_jiffies; @@ -56,6 +58,7 @@ static int gpio_wdt_start(struct watchdog_device *wdd) gpio_direction_output(priv->gpio, priv->state); priv->last_jiffies = jiffies; mod_timer(&priv->timer, priv->last_jiffies + priv->hw_margin); + priv->armed = true; return 0; } @@ -64,8 +67,11 @@ 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; } @@ -91,7 +97,7 @@ 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 + + if (priv->armed && time_after(jiffies, priv->last_jiffies + msecs_to_jiffies(wdd->timeout * 1000))) {
Please align continuation lines.
dev_crit(wdd->dev, "Timer expired. System will reboot soon!\n"); return; @@ -197,6 +203,9 @@ 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"); +
Please align continuation line with '('.
watchdog_set_drvdata(&priv->wdd, priv); priv->wdd.info = &gpio_wdt_ident; @@ -218,6 +227,11 @@ static int gpio_wdt_probe(struct platform_device *pdev) if (ret) watchdog_unregister_device(&priv->wdd); + if (priv->always_running) { + gpio_wdt_start(&priv->wdd); + priv->armed = false; + } +
This won't work if there is an error. The driver won't load but the timer is started, which will likely cause a crash when the timer fires. You'll have to fix the error handling. I also dislike that you first set priv->armed in the start function and then reset it, but I don't have a better idea right now. Guenter
return ret; }
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