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

From: Guenter Roeck <linux@roeck-us.net>
To: Xiantao Hu <xt.hu@cqplus1.com>
Cc: wim@linux-watchdog.org, p.zabel@pengutronix.de,
	linux-kernel@vger.kernel.org, linux-watchdog@vger.kernel.org,
	robh+dt@kernel.org, devicetree@vger.kernel.org,
	wells.lu@sunplus.com, qinjian@cqplus1.com
Subject: Re: [PATCH v2 1/2] watchdog: Add watchdog driver for Sunplus SP7021
Date: Wed, 24 Nov 2021 06:25:22 -0800	[thread overview]
Message-ID: <20211124142522.GA3939252@roeck-us.net> (raw)
In-Reply-To: <20211124104149.361019-2-xt.hu@cqplus1.com>

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@cqplus1.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