linux-kernel - Re: [PATCH 1/2] watchdog: add wdt suspend/resume support

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Message-ID: <55AF11CD.3070801@roeck-us.net>
Date:	Tue, 21 Jul 2015 20:45:17 -0700
From:	Guenter Roeck <linux@...ck-us.net>
To:	Eddie Huang <eddie.huang@...iatek.com>,
	Wim Van Sebroeck <wim@...ana.be>
CC:	Matthias Brugger <matthias.bgg@...il.com>,
	linux-watchdog@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-mediatek@...ts.infradead.org, linux-kernel@...r.kernel.org,
	Sascha Hauer <kernel@...gutronix.de>,
	Greta Zhang <greta.zhang@...iatek.com>,
	Roger Lu <roger.lu@...iatek.com>
Subject: Re: [PATCH 1/2] watchdog: add wdt suspend/resume support

On 07/21/2015 08:26 PM, Eddie Huang wrote:
> From: Greta Zhang <greta.zhang@...iatek.com>
>
> add wdt driver suspend/resume support
>
> Signed-off-by: Greta Zhang <greta.zhang@...iatek.com>
> Signed-off-by: Roger Lu <roger.lu@...iatek.com>
> Signed-off-by: Eddie Huang <eddie.huang@...iatek.com>
> ---
>   drivers/watchdog/mtk_wdt.c | 38 ++++++++++++++++++++++++++++++++++++++
>   1 file changed, 38 insertions(+)
>
> diff --git a/drivers/watchdog/mtk_wdt.c b/drivers/watchdog/mtk_wdt.c
> index 938b987..5ef3910 100644
> --- a/drivers/watchdog/mtk_wdt.c
> +++ b/drivers/watchdog/mtk_wdt.c
> @@ -65,6 +65,7 @@ struct mtk_wdt_dev {
>   	struct watchdog_device wdt_dev;
>   	void __iomem *wdt_base;
>   	struct notifier_block restart_handler;
> +	bool started;

Any reason why you can not use watchdog_active() ?

>   };
>
>   static int mtk_reset_handler(struct notifier_block *this, unsigned long mode,
> @@ -125,6 +126,8 @@ static int mtk_wdt_stop(struct watchdog_device *wdt_dev)
>   	reg &= ~WDT_MODE_EN;
>   	iowrite32(reg, wdt_base + WDT_MODE);
>
> +	mtk_wdt->started = false;
> +
>   	return 0;
>   }
>
> @@ -135,6 +138,8 @@ static int mtk_wdt_start(struct watchdog_device *wdt_dev)
>   	void __iomem *wdt_base = mtk_wdt->wdt_base;
>   	int ret;
>
> +	mtk_wdt->started = true;
> +
>   	ret = mtk_wdt_set_timeout(wdt_dev, wdt_dev->timeout);
>   	if (ret < 0)
>   		return ret;
> @@ -174,6 +179,8 @@ static int mtk_wdt_probe(struct platform_device *pdev)
>
>   	platform_set_drvdata(pdev, mtk_wdt);
>
> +	mtk_wdt->started = false;
> +
>   	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>   	mtk_wdt->wdt_base = devm_ioremap_resource(&pdev->dev, res);
>   	if (IS_ERR(mtk_wdt->wdt_base))
> @@ -221,6 +228,35 @@ static int mtk_wdt_remove(struct platform_device *pdev)
>   	return 0;
>   }
>
> +#ifdef CONFIG_PM
> +static int mtk_wdt_suspend(struct platform_device *pdev, pm_message_t state)
> +{
> +	struct mtk_wdt_dev *mtk_wdt = platform_get_drvdata(pdev);
> +
> +	if (mtk_wdt->started) {
> +		mtk_wdt_stop(&mtk_wdt->wdt_dev);
> +		mtk_wdt->started = true;

?????

> +	}
> +
> +	return 0;
> +}
> +
> +static int mtk_wdt_resume(struct platform_device *pdev)
> +{
> +	struct mtk_wdt_dev *mtk_wdt = platform_get_drvdata(pdev);
> +
> +	if (mtk_wdt->started) {
> +		mtk_wdt_start(&mtk_wdt->wdt_dev);
> +		mtk_wdt_ping(&mtk_wdt->wdt_dev);
> +	}
> +
> +	return 0;
> +}
> +#else
> +#define	mtk_wdt_suspend	NULL
> +#define	mtk_wdt_resume	NULL
> +#endif
> +
>   static const struct of_device_id mtk_wdt_dt_ids[] = {
>   	{ .compatible = "mediatek,mt6589-wdt" },
>   	{ /* sentinel */ }
> @@ -230,6 +266,8 @@ MODULE_DEVICE_TABLE(of, mtk_wdt_dt_ids);
>   static struct platform_driver mtk_wdt_driver = {
>   	.probe		= mtk_wdt_probe,
>   	.remove		= mtk_wdt_remove,
> +	.suspend	= mtk_wdt_suspend,
> +	.resume		= mtk_wdt_resume,
>   	.driver		= {
>   		.name		= DRV_NAME,
>   		.of_match_table	= mtk_wdt_dt_ids,

Typically drivers would use struct dev_pm_ops and
                 .pm = &mtk_wdt_pm_ops,

Any reason for not using the same mechanism ?

Thanks,
Guenter

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