linux-kernel - Re: [PATCH 1/2] watchdog: aspeed: Add pre-timeout interrupt support

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Message-ID: <20221021165650.GA1888515@roeck-us.net>
Date:   Fri, 21 Oct 2022 09:56:50 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Eddie James <eajames@...ux.ibm.com>
Cc:     linux-watchdog@...r.kernel.org, linux-aspeed@...ts.ozlabs.org,
        linux-kernel@...r.kernel.org, wim@...ux-watchdog.org,
        andrew@...id.au, joel@....id.au, robh+dt@...nel.org,
        krzysztof.kozlowski+dt@...aro.org, devicetree@...r.kernel.org
Subject: Re: [PATCH 1/2] watchdog: aspeed: Add pre-timeout interrupt support

On Fri, Oct 21, 2022 at 10:15:58AM -0500, Eddie James wrote:
> Enable the pre-timeout interrupt if requested by device property.
> 

I am not inclined to accept this patch without detailed explanation.
Why would it make sense and/or be desirable to completely bypass the
watchdog core with this pretimeout support ?

Thanks,
Guenter

> Signed-off-by: Eddie James <eajames@...ux.ibm.com>
> ---
>  drivers/watchdog/aspeed_wdt.c | 53 +++++++++++++++++++++++++++++++++--
>  1 file changed, 51 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/watchdog/aspeed_wdt.c b/drivers/watchdog/aspeed_wdt.c
> index 0cff2adfbfc9..8e12181a827e 100644
> --- a/drivers/watchdog/aspeed_wdt.c
> +++ b/drivers/watchdog/aspeed_wdt.c
> @@ -5,11 +5,14 @@
>   * Joel Stanley <joel@....id.au>
>   */
>  
> +#include <linux/bits.h>
>  #include <linux/delay.h>
> +#include <linux/interrupt.h>
>  #include <linux/io.h>
>  #include <linux/kernel.h>
>  #include <linux/module.h>
>  #include <linux/of.h>
> +#include <linux/of_irq.h>
>  #include <linux/platform_device.h>
>  #include <linux/watchdog.h>
>  
> @@ -26,20 +29,32 @@ struct aspeed_wdt {
>  
>  struct aspeed_wdt_config {
>  	u32 ext_pulse_width_mask;
> +	u32 irq_shift;
> +	u32 irq_mask;
>  };
>  
>  static const struct aspeed_wdt_config ast2400_config = {
>  	.ext_pulse_width_mask = 0xff,
> +	.irq_shift = 0,
> +	.irq_mask = 0,
>  };
>  
>  static const struct aspeed_wdt_config ast2500_config = {
>  	.ext_pulse_width_mask = 0xfffff,
> +	.irq_shift = 12,
> +	.irq_mask = GENMASK(31, 12),
> +};
> +
> +static const struct aspeed_wdt_config ast2600_config = {
> +	.ext_pulse_width_mask = 0xfffff,
> +	.irq_shift = 0,
> +	.irq_mask = GENMASK(31, 10),
>  };
>  
>  static const struct of_device_id aspeed_wdt_of_table[] = {
>  	{ .compatible = "aspeed,ast2400-wdt", .data = &ast2400_config },
>  	{ .compatible = "aspeed,ast2500-wdt", .data = &ast2500_config },
> -	{ .compatible = "aspeed,ast2600-wdt", .data = &ast2500_config },
> +	{ .compatible = "aspeed,ast2600-wdt", .data = &ast2600_config },
>  	{ },
>  };
>  MODULE_DEVICE_TABLE(of, aspeed_wdt_of_table);
> @@ -58,6 +73,7 @@ MODULE_DEVICE_TABLE(of, aspeed_wdt_of_table);
>  #define   WDT_CTRL_RESET_SYSTEM		BIT(1)
>  #define   WDT_CTRL_ENABLE		BIT(0)
>  #define WDT_TIMEOUT_STATUS	0x10
> +#define   WDT_TIMEOUT_STATUS_IRQ		BIT(2)
>  #define   WDT_TIMEOUT_STATUS_BOOT_SECONDARY	BIT(1)
>  #define WDT_CLEAR_TIMEOUT_STATUS	0x14
>  #define   WDT_CLEAR_TIMEOUT_AND_BOOT_CODE_SELECTION	BIT(0)
> @@ -243,6 +259,17 @@ static const struct watchdog_info aspeed_wdt_info = {
>  	.identity	= KBUILD_MODNAME,
>  };
>  
> +static irqreturn_t aspeed_wdt_irq(int irq, void *arg)
> +{
> +	struct aspeed_wdt *wdt = arg;
> +	u32 status = readl(wdt->base + WDT_TIMEOUT_STATUS);
> +
> +	if (status & WDT_TIMEOUT_STATUS_IRQ)
> +		panic("Watchdog pre-timeout IRQ");
> +
> +	return IRQ_NONE;
> +}
> +
>  static int aspeed_wdt_probe(struct platform_device *pdev)
>  {
>  	struct device *dev = &pdev->dev;
> @@ -253,6 +280,7 @@ static int aspeed_wdt_probe(struct platform_device *pdev)
>  	const char *reset_type;
>  	u32 duration;
>  	u32 status;
> +	u32 timeout = 0;
>  	int ret;
>  
>  	wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
> @@ -291,6 +319,27 @@ static int aspeed_wdt_probe(struct platform_device *pdev)
>  	if (of_device_is_compatible(np, "aspeed,ast2400-wdt"))
>  		wdt->ctrl = WDT_CTRL_1MHZ_CLK;
>  
> +	if (config->irq_mask) {
> +		if (!of_property_read_u32(np, "aspeed,pre-timeout-irq-us", &timeout) && timeout) {
> +			int irq =  platform_get_irq(pdev, 0);
> +
> +			if (irq < 0) {
> +				dev_warn(dev, "Couldn't find IRQ: %d\n", irq);
> +				timeout = 0;
> +			} else {
> +				ret = devm_request_irq(dev, irq, aspeed_wdt_irq, IRQF_SHARED,
> +						       dev_name(dev), wdt);
> +				if (ret) {
> +					dev_warn(dev, "Couldn't request IRQ:%d\n", ret);
> +					timeout = 0;
> +				} else {
> +					wdt->ctrl |= ((timeout << config->irq_shift) &
> +						      config->irq_mask) | WDT_CTRL_WDT_INTR;
> +				}
> +			}
> +		}
> +	}
> +
>  	/*
>  	 * Control reset on a per-device basis to ensure the
>  	 * host is not affected by a BMC reboot
> @@ -308,7 +357,7 @@ static int aspeed_wdt_probe(struct platform_device *pdev)
>  		else if (!strcmp(reset_type, "system"))
>  			wdt->ctrl |= WDT_CTRL_RESET_MODE_FULL_CHIP |
>  				     WDT_CTRL_RESET_SYSTEM;
> -		else if (strcmp(reset_type, "none"))
> +		else if (strcmp(reset_type, "none") && !timeout)
>  			return -EINVAL;
>  	}
>  	if (of_property_read_bool(np, "aspeed,external-signal"))
> -- 
> 2.31.1
>