linux-kernel - Re: [PATCH] watchdog: qcom: add support for the bark interrupt

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Date:   Thu, 5 Sep 2019 09:39:19 -0700
From:   Bjorn Andersson <bjorn.andersson@...aro.org>
To:     Jorge Ramirez-Ortiz <jorge.ramirez-ortiz@...aro.org>
Cc:     agross@...nel.org, wim@...ux-watchdog.org,
        linux-arm-msm@...r.kernel.org, linux-watchdog@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] watchdog: qcom: add support for the bark interrupt

On Thu 05 Sep 09:21 PDT 2019, Jorge Ramirez-Ortiz wrote:

> Use the bark interrupt to notify the bark event. Since the bark and bite
> timeouts are identical, increase the bite timeout by one second so
> that the bark event can be logged to the console.
> 

Afaict you should tie the bark to the "pretimeout" in the watchdog
framework , which would allow the user to specify a pretimeout and
configure what should happen at the bark (just a pr_alert() or panic()).

Regards,
Bjorn

> Signed-off-by: Jorge Ramirez-Ortiz <jorge.ramirez-ortiz@...aro.org>
> ---
>  drivers/watchdog/qcom-wdt.c | 42 ++++++++++++++++++++++++++++++++++---
>  1 file changed, 39 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/watchdog/qcom-wdt.c b/drivers/watchdog/qcom-wdt.c
> index 7be7f87be28f..5eaf92084b93 100644
> --- a/drivers/watchdog/qcom-wdt.c
> +++ b/drivers/watchdog/qcom-wdt.c
> @@ -10,6 +10,7 @@
>  #include <linux/platform_device.h>
>  #include <linux/watchdog.h>
>  #include <linux/of_device.h>
> +#include <linux/interrupt.h>
>  
>  enum wdt_reg {
>  	WDT_RST,
> @@ -41,6 +42,8 @@ struct qcom_wdt {
>  	unsigned long		rate;
>  	void __iomem		*base;
>  	const u32		*layout;
> +	unsigned int		irq;
> +	const struct device	*dev;
>  };
>  
>  static void __iomem *wdt_addr(struct qcom_wdt *wdt, enum wdt_reg reg)
> @@ -54,15 +57,37 @@ struct qcom_wdt *to_qcom_wdt(struct watchdog_device *wdd)
>  	return container_of(wdd, struct qcom_wdt, wdd);
>  }
>  
> +static inline int qcom_wdt_enable(struct qcom_wdt *wdt)
> +{
> +	if (wdt->irq < 0)
> +		return 1;
> +
> +	/* enable timeout with interrupt */
> +	return 3;
> +}
> +
> +static irqreturn_t qcom_wdt_irq(int irq, void *cookie)
> +{
> +	struct qcom_wdt *wdt =  (struct qcom_wdt *) cookie;
> +
> +	dev_warn(wdt->dev, "barking, one second countdown to reset\n");
> +
> +	return IRQ_HANDLED;
> +}
> +
>  static int qcom_wdt_start(struct watchdog_device *wdd)
>  {
>  	struct qcom_wdt *wdt = to_qcom_wdt(wdd);
> +	unsigned int bark, bite;
> +
> +	bark = wdd->timeout;
> +	bite = wdt->irq < 0 ? bark : bark + 1;
>  
>  	writel(0, wdt_addr(wdt, WDT_EN));
>  	writel(1, wdt_addr(wdt, WDT_RST));
> -	writel(wdd->timeout * wdt->rate, wdt_addr(wdt, WDT_BARK_TIME));
> -	writel(wdd->timeout * wdt->rate, wdt_addr(wdt, WDT_BITE_TIME));
> -	writel(1, wdt_addr(wdt, WDT_EN));
> +	writel(bark * wdt->rate, wdt_addr(wdt, WDT_BARK_TIME));
> +	writel(bite * wdt->rate, wdt_addr(wdt, WDT_BITE_TIME));
> +	writel(qcom_wdt_enable(wdt), wdt_addr(wdt, WDT_EN));
>  	return 0;
>  }
>  
> @@ -210,10 +235,21 @@ static int qcom_wdt_probe(struct platform_device *pdev)
>  	wdt->wdd.max_timeout = 0x10000000U / wdt->rate;
>  	wdt->wdd.parent = dev;
>  	wdt->layout = regs;
> +	wdt->dev = &pdev->dev;
>  
>  	if (readl(wdt_addr(wdt, WDT_STS)) & 1)
>  		wdt->wdd.bootstatus = WDIOF_CARDRESET;
>  
> +	wdt->irq = platform_get_irq(pdev, 0);
> +	if (wdt->irq >= 0) {
> +		ret = devm_request_irq(&pdev->dev, wdt->irq, qcom_wdt_irq,
> +				       IRQF_TRIGGER_RISING, "wdog_bark", wdt);
> +		if (ret) {
> +			dev_err(&pdev->dev, "failed to request irq\n");
> +			return ret;
> +		}
> +	}
> +
>  	/*
>  	 * If 'timeout-sec' unspecified in devicetree, assume a 30 second
>  	 * default, unless the max timeout is less than 30 seconds, then use
> -- 
> 2.23.0
>