linux-kernel - Re: [PATCH 2/3] watchdog: aspeed: Support variable number of reset mask registers

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Message-ID: <83a90651-0b46-4c68-ab90-361422192e90@roeck-us.net>
Date: Tue, 7 Oct 2025 07:55:23 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: Chin-Ting Kuo <chin-ting_kuo@...eedtech.com>, wim@...ux-watchdog.org,
 robh@...nel.org, krzk+dt@...nel.org, conor+dt@...nel.org, joel@....id.au,
 andrew@...econstruct.com.au, linux-watchdog@...r.kernel.org,
 devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
 linux-aspeed@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
 BMC-SW@...eedtech.com
Subject: Re: [PATCH 2/3] watchdog: aspeed: Support variable number of reset
 mask registers

On 10/7/25 01:36, Chin-Ting Kuo wrote:
> Starting from the AST2600 platform, the SoC design has become more
> complex, with an increased number of reset mask registers.
> To support this, introduce a new field 'num_reset_masks' in the
> 'aspeed_wdt_config' structure to specify the number of reset mask
> registers per platform. This change removes the need for hardcoded
> platform-specific logic and improves scalability for future SoCs.
> 
> Signed-off-by: Chin-Ting Kuo <chin-ting_kuo@...eedtech.com>
> ---
>   drivers/watchdog/aspeed_wdt.c | 12 ++++++++----
>   1 file changed, 8 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/watchdog/aspeed_wdt.c b/drivers/watchdog/aspeed_wdt.c
> index 837e15701c0e..e15f70c5e416 100644
> --- a/drivers/watchdog/aspeed_wdt.c
> +++ b/drivers/watchdog/aspeed_wdt.c
> @@ -35,6 +35,7 @@ struct aspeed_wdt_config {
>   	u32 irq_shift;
>   	u32 irq_mask;
>   	struct aspeed_wdt_scu scu;
> +	u32 num_reset_masks;
>   };
>   
>   struct aspeed_wdt {
> @@ -54,6 +55,7 @@ static const struct aspeed_wdt_config ast2400_config = {
>   		.wdt_reset_mask = 0x1,
>   		.wdt_reset_mask_shift = 1,
>   	},
> +	.num_reset_masks = 1,

Looking at this again: Why set it on ast2400 ?

>   };
>   
>   static const struct aspeed_wdt_config ast2500_config = {
> @@ -66,6 +68,7 @@ static const struct aspeed_wdt_config ast2500_config = {
>   		.wdt_reset_mask = 0x1,
>   		.wdt_reset_mask_shift = 2,
>   	},
> +	.num_reset_masks = 1,
>   };
>   
>   static const struct aspeed_wdt_config ast2600_config = {
> @@ -78,6 +81,7 @@ static const struct aspeed_wdt_config ast2600_config = {
>   		.wdt_reset_mask = 0xf,
>   		.wdt_reset_mask_shift = 16,
>   	},
> +	.num_reset_masks = 2,
>   };
>   
>   static const struct of_device_id aspeed_wdt_of_table[] = {
> @@ -482,8 +486,9 @@ static int aspeed_wdt_probe(struct platform_device *pdev)
>   	if ((of_device_is_compatible(np, "aspeed,ast2500-wdt")) ||
>   		(of_device_is_compatible(np, "aspeed,ast2600-wdt"))) {

... because the code here only evaluates it if this is an ast2500 or ast2600.

If num_reset_masks would be set to 0 for ast2400, the value could be used here.

	if (wdt->cfg->num_reset_masks) {
		...
	}

and it would not be necessary to add of_device_is_compatible() for new chips.

Guenter

>   		u32 reset_mask[2];
> -		size_t nrstmask = of_device_is_compatible(np, "aspeed,ast2600-wdt") ? 2 : 1;
> +		size_t nrstmask = wdt->cfg->num_reset_masks;
>   		u32 reg = readl(wdt->base + WDT_RESET_WIDTH);
> +		int i;
>   
>   		reg &= wdt->cfg->ext_pulse_width_mask;
>   		if (of_property_read_bool(np, "aspeed,ext-active-high"))
> @@ -503,9 +508,8 @@ static int aspeed_wdt_probe(struct platform_device *pdev)
>   
>   		ret = of_property_read_u32_array(np, "aspeed,reset-mask", reset_mask, nrstmask);
>   		if (!ret) {
> -			writel(reset_mask[0], wdt->base + WDT_RESET_MASK1);
> -			if (nrstmask > 1)
> -				writel(reset_mask[1], wdt->base + WDT_RESET_MASK2);
> +			for (i = 0; i < nrstmask; i++)
> +				writel(reset_mask[i], wdt->base + WDT_RESET_MASK1 + i * 4);
>   		}
>   	}
>