linux-kernel - RE: [PATCH v3 2/4] watchdog: da9062: reset board on watchdog timeout

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Message-ID: <DB9PR10MB4652EF562CD20FB72FDBD71880689@DB9PR10MB4652.EURPRD10.PROD.OUTLOOK.COM>
Date:   Wed, 1 Dec 2021 20:05:08 +0000
From:   Adam Thomson <Adam.Thomson.Opensource@...semi.com>
To:     Andrej Picej <andrej.picej@...ik.com>,
        Support Opensource <Support.Opensource@...semi.com>,
        "linux@...ck-us.net" <linux@...ck-us.net>,
        "linux-watchdog@...r.kernel.org" <linux-watchdog@...r.kernel.org>
CC:     "wim@...ux-watchdog.org" <wim@...ux-watchdog.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "shawnguo@...nel.org" <shawnguo@...nel.org>,
        "s.hauer@...gutronix.de" <s.hauer@...gutronix.de>,
        "kernel@...gutronix.de" <kernel@...gutronix.de>,
        "festevam@...il.com" <festevam@...il.com>,
        "linux-imx@....com" <linux-imx@....com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>
Subject: RE: [PATCH v3 2/4] watchdog: da9062: reset board on watchdog timeout

On 01 December 2021 08:15, Andrej Picej wrote:

> Implement a method to change watchdog timeout configuration based on DT
> binding ("dlg,wdt-sd"). There is a possibility to change the bahaviour
> of watchdog reset. Setting WATCHDOG_SD bit enables SHUTDOWN mode, and
> clearing it enables POWERDOWN mode on watchdog timeout.
> 
> If no DT binding is specified the WATCHDOG_SD bit stays in default
> configuration, not breaking behaviour of devices which might depend on
> default fuse configuration.
> 
> Note: This patch requires that the config register CONFIG_I is
> configured as writable in the da9062 multi function device.
> 
> Signed-off-by: Andrej Picej <andrej.picej@...ik.com>
> ---
> Changes in v3:
>  - no changes
> 
> Changes in v2:
>  - don't force the "reset" for all da9062-watchdog users, instead add DT
>    binding where the behavior can be selected
> ---
>  drivers/watchdog/da9062_wdt.c | 25 +++++++++++++++++++++++++
>  1 file changed, 25 insertions(+)
> 
> diff --git a/drivers/watchdog/da9062_wdt.c b/drivers/watchdog/da9062_wdt.c
> index f02cbd530538..e342e9e50cb1 100644
> --- a/drivers/watchdog/da9062_wdt.c
> +++ b/drivers/watchdog/da9062_wdt.c
> @@ -85,8 +85,33 @@ static int da9062_wdt_start(struct watchdog_device *wdd)
>  {
>  	struct da9062_watchdog *wdt = watchdog_get_drvdata(wdd);
>  	unsigned int selector;
> +	unsigned int mask;
> +	u32 val;
>  	int ret;
> 
> +	/* Configure what happens on watchdog timeout. Can be specified with
> +	 * "dlg,wdt-sd" dt-binding (0 -> POWERDOWN, 1 -> SHUTDOWN).
> +	 * If "dlg,wdt-sd" dt-binding is NOT set use the default.
> +	 */
> +	ret = device_property_read_u32(wdd->parent, "dlg,wdt-sd", &val);
> +	if (!ret) {
> +		if (val)
> +			/* Use da9062's SHUTDOWN mode */
> +			mask = DA9062AA_WATCHDOG_SD_MASK;
> +		else
> +			/* Use da9062's POWERDOWN mode. */
> +			mask = 0x0;
> +
> +		ret = regmap_update_bits(wdt->hw->regmap,
> +						DA9062AA_CONFIG_I,
> +
> 	DA9062AA_WATCHDOG_SD_MASK,
> +						mask);
> +
> +		if (ret)
> +			dev_err(wdt->hw->dev, "failed to set wdt reset mode:
> %d\n",
> +				ret);
> +	}
> +

Personally I'd stick this code in the probe(). The value won't change once it's
set, and that seems the more logical place for it in my opinion.

>  	selector = da9062_wdt_timeout_to_sel(wdt->wdtdev.timeout);
>  	ret = da9062_wdt_update_timeout_register(wdt, selector);
>  	if (ret)
> --
> 2.25.1