Hi
	Thanks for your review. I explain this in detail below the comment.

Best Regards,
Xiantao

-----Original Message-----
From: Guenter Roeck [mailto:groeck7@gmail.com] On Behalf Of Guenter Roeck
Sent: Wednesday, November 24, 2021 10:25 PM
To: xt.hu[胡先韬] <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 呂芳騰
[off-list ref]; qinjian[覃健] [off-list ref]
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:

quoted

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.

The register used by this driver consists of two parts. The first part which contains WDT_CTRL and WDT_CNT 
registers is exclusive by watchdog. 
In specially, the second part is belong to a multifunctional register group which control IP and bus. Refer to 
register manual below:
-------------------------------------------------------------------------------------------------------------------------------------------------
MO1_STC_WDG_RST_EN	4	RW		STC Watchdog Timeout Trigger System Reset Enable
									0: STC watchdog 2 timeout will not trigger system reset(default)
									1: STC watchdog 2 timeout will trigger system reset
MO1_RI_WDG_RST_EN		1	RW		RBUS Watchdog Timeout Trigger System Reset Enable
									0: RBUS watchdog timeout will not trigger system reset(default)
									1: RBUS watchdog timeout will trigger system reset
MO1_TIMER_STAND_BY_EN	0	RW		Timer Standby Mode Enable
									0: Disable (default)
									1: Enable Active high to enter timer standby mode, 
											default not in standby mode
-------------------------------------------------------------------------------------------------------------------------------------------------
You can see that in addition to the bits for watchdog there are bit fields for other modules.
I use this register bit4 and bit1. Default value is 0 that watchdog internal interrupt signal can't trigger system 
and RBUS reset. I need set 1 when watchdog probe. Early I implement the operation in 
arch/arm/mach-sunplus/sp7021.c and configure by macro. But in arch/arm64, directory mach-XXX is removed.
So I solve in this way. Any better way?

Thanks,
Guenter