linux-kernel - Re: [PATCH v2 1/2] watchdog: Add watchdog driver for Sunplus SP7021

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Date:   Wed, 24 Nov 2021 06:25:22 -0800
From:   Guenter Roeck <linux@...ck-us.net>
To:     Xiantao Hu <xt.hu@...lus1.com>
Cc:     wim@...ux-watchdog.org, p.zabel@...gutronix.de,
        linux-kernel@...r.kernel.org, linux-watchdog@...r.kernel.org,
        robh+dt@...nel.org, devicetree@...r.kernel.org,
        wells.lu@...plus.com, qinjian@...lus1.com
Subject: Re: [PATCH v2 1/2] watchdog: Add watchdog driver for Sunplus SP7021

On Wed, Nov 24, 2021 at 06:41:48PM +0800, Xiantao Hu wrote:
> Sunplus SP7021 requires watchdog timer support.
> Add watchdog driver to enable this.
> 
> Signed-off-by: Xiantao Hu <xt.hu@...lus1.com>
> ---
> +
> +	priv->base = devm_platform_ioremap_resource(pdev, 0);
> +	if (IS_ERR(priv->base))
> +		return PTR_ERR(priv->base);
> +
> +	/* The registers accessed here shared by multiple drivers. */
> +	wdt_res = platform_get_resource(pdev, IORESOURCE_MEM, 1);

This is unusual. Why would other drivers access WDT_CTRL and WDT_CNT
registers, and how is it ensured that the other drivers do not interfer
with the accesses by this driver ?

Normally such a resource would be shared through a parent driver with
appropriate access functions to ensure that accesses are synchronized.

Thanks,
Guenter