linux-kernel - Re: [PATCH RESEND v4 2/2] watchdog: rti

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Message-ID: <8af0bb91-bca8-4c62-ae9b-a4eb91223a2e@ti.com>
Date: Tue, 3 Feb 2026 13:13:53 -0600
From: Andrew Davis <afd@...com>
To: Judith Mendez <jm@...com>, Wim Van Sebroeck <wim@...ux-watchdog.org>,
	Guenter Roeck <linux@...ck-us.net>, Rob Herring <robh@...nel.org>, "Krzysztof
 Kozlowski" <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>
CC: Tero Kristo <kristo@...nel.org>, <linux-watchdog@...r.kernel.org>,
	<devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH RESEND v4 2/2] watchdog: rti_wdt: Add reaction control

On 2/3/26 12:19 PM, Judith Mendez wrote:
> This allows to configure reaction between NMI and reset for WWD.
> 
> On K3 SoC's other than AM62L SoC [0], watchdog reset output is routed
> to the ESM module which can subsequently route the signal to safety
> master or SoC reset. On AM62L, the watchdog reset output is routed
> to the SoC HW reset block. So, add a new compatible for AM62l to add
> SoC data and configure reaction to reset instead of NMI.
> 
> [0] https://www.ti.com/product/AM62L
> Signed-off-by: Judith Mendez <jm@...com>
> ---
>   drivers/watchdog/rti_wdt.c | 32 ++++++++++++++++++++++++++++----
>   1 file changed, 28 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/watchdog/rti_wdt.c b/drivers/watchdog/rti_wdt.c
> index be7d7db475911..483e22efedf9b 100644
> --- a/drivers/watchdog/rti_wdt.c
> +++ b/drivers/watchdog/rti_wdt.c
> @@ -35,7 +35,8 @@
>   #define RTIWWDRXCTRL	0xa4
>   #define RTIWWDSIZECTRL	0xa8
>   
> -#define RTIWWDRX_NMI	0xa
> +#define RTIWWDRXN_RST	0x5
> +#define RTIWWDRXN_NMI	0xa
>   
>   #define RTIWWDSIZE_50P		0x50
>   #define RTIWWDSIZE_25P		0x500
> @@ -63,22 +64,29 @@
>   
>   static int heartbeat;
>   
> +struct rti_wdt_data {
> +	bool nmi;
> +};
> +
>   /*
>    * struct to hold data for each WDT device
>    * @base - base io address of WD device
>    * @freq - source clock frequency of WDT
>    * @wdd  - hold watchdog device as is in WDT core
> + * @data - hold configuration data
>    */
>   struct rti_wdt_device {
>   	void __iomem		*base;
>   	unsigned long		freq;
>   	struct watchdog_device	wdd;
> +	const struct rti_wdt_data *data;

Don't store the whole device match data struct, just store the
information you need, so

* @nmi - Set to true if this WDT instance supports generating NMI
bool nmi;

>   };
>   
>   static int rti_wdt_start(struct watchdog_device *wdd)
>   {
>   	u32 timer_margin;
>   	struct rti_wdt_device *wdt = watchdog_get_drvdata(wdd);
> +	u8 reaction;
>   	int ret;
>   
>   	ret = pm_runtime_resume_and_get(wdd->parent);
> @@ -101,8 +109,13 @@ static int rti_wdt_start(struct watchdog_device *wdd)
>   	 */
>   	wdd->min_hw_heartbeat_ms = 520 * wdd->timeout + MAX_HW_ERROR;
>   
> -	/* Generate NMI when wdt expires */
> -	writel_relaxed(RTIWWDRX_NMI, wdt->base + RTIWWDRXCTRL);
> +	/* Reset device if wdt serviced outside of window or generate NMI if available */

I think where we had issues before was this comment, it should match the code
and it can do so while being very similar to the comment as it was before:

/* When WDT expires, generate an NMI or reset the device if NMI is not supported */

> +	if (wdt->data->nmi)
> +		reaction = RTIWWDRXN_NMI;
> +	else
> +		reaction = RTIWWDRXN_RST;
> +
> +	writel_relaxed(reaction, wdt->base + RTIWWDRXCTRL);
>   
>   	/* Open window size 50%; this is the largest window size available */
>   	writel_relaxed(RTIWWDSIZE_50P, wdt->base + RTIWWDSIZECTRL);
> @@ -254,6 +267,8 @@ static int rti_wdt_probe(struct platform_device *pdev)
>   	wdd->timeout = DEFAULT_HEARTBEAT;
>   	wdd->parent = dev;
>   
> +	wdt->data = device_get_match_data(dev);

Should be rare, but this can fail to find match data so you should
check for NULL here. Then as above, just extract out the data you
need (nmi).

Andrew

> +
>   	watchdog_set_drvdata(wdd, wdt);
>   	watchdog_set_nowayout(wdd, 1);
>   	watchdog_set_restart_priority(wdd, 128);
> @@ -361,8 +376,17 @@ static void rti_wdt_remove(struct platform_device *pdev)
>   	pm_runtime_disable(&pdev->dev);
>   }
>   
> +static struct rti_wdt_data j7_wdt = {
> +	.nmi = true,
> +};
> +
> +static struct rti_wdt_data am62l_wdt = {
> +	.nmi = false,
> +};
> +
>   static const struct of_device_id rti_wdt_of_match[] = {
> -	{ .compatible = "ti,j7-rti-wdt", },
> +	{ .compatible = "ti,j7-rti-wdt", .data = &j7_wdt },
> +	{ .compatible = "ti,am62l-rti-wdt", .data = &am62l_wdt },
>   	{},
>   };
>   MODULE_DEVICE_TABLE(of, rti_wdt_of_match);