Re: [PATCH v2 2/2] watchdog: imx2_wdt: add set_pretimeout interface

[Guenter Roeck <linux@roeck-us.net>]

On 11/03/2015 12:04 AM, Robin Gong wrote:
> On Mon, Nov 02, 2015 at 11:48:29PM -0800, Guenter Roeck wrote:
>> On 11/02/2015 10:11 PM, Robin Gong wrote:
>>> Enable set_pretimeout interface and trigger the pretimeout interrupt before
>>> watchdog timeout event happen.
>>>
>>> Signed-off-by: Robin Gong <b38343@freescale.com>
>>> ---
>>>   drivers/watchdog/imx2_wdt.c | 58 ++++++++++++++++++++++++++++++++++++++++++++-
>>>   1 file changed, 57 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/watchdog/imx2_wdt.c b/drivers/watchdog/imx2_wdt.c
>>> index 0bb1a1d..bd42857 100644
>>> --- a/drivers/watchdog/imx2_wdt.c
>>> +++ b/drivers/watchdog/imx2_wdt.c
>>> @@ -24,6 +24,7 @@
>>>   #include <linux/clk.h>
>>>   #include <linux/delay.h>
>>>   #include <linux/init.h>
>>> +#include <linux/interrupt.h>
>>>   #include <linux/io.h>
>>>   #include <linux/jiffies.h>
>>>   #include <linux/kernel.h>
>>> @@ -52,12 +53,18 @@
>>>   #define IMX2_WDT_WRSR		0x04		/* Reset Status Register */
>>>   #define IMX2_WDT_WRSR_TOUT	(1 << 1)	/* -> Reset due to Timeout */
>>>
>>> +#define IMX2_WDT_WICR		0x06		/*Interrupt Control Register*/
>>> +#define IMX2_WDT_WICR_WIE	(1 << 15)	/* -> Interrupt Enable */
>>> +#define IMX2_WDT_WICR_WTIS	(1 << 14)	/* -> Interrupt Status */
>>> +#define IMX2_WDT_WICR_WICT	(0xFF)	/* Watchdog Interrupt Timeout */
>>
>> Unnecessary ( )
>>
>>> +
>>>   #define IMX2_WDT_WMCR		0x08		/* Misc Register */
>>>
>>>   #define IMX2_WDT_MAX_TIME	128
>>>   #define IMX2_WDT_DEFAULT_TIME	60		/* in seconds */
>>>
>>>   #define WDOG_SEC_TO_COUNT(s)	((s * 2 - 1) << 8)
>>> +#define WDOG_SEC_TO_PRECOUNT(s)	((s) * 2)	/* set WDOG pre timeout count*/
>>>
>>>   struct imx2_wdt_device {
>>>   	struct clk *clk;
>>> @@ -80,7 +87,8 @@ MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds (default="
>>>
>>>   static const struct watchdog_info imx2_wdt_info = {
>>>   	.identity = "imx2+ watchdog",
>>> -	.options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
>>> +	.options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE
>>> +		   | WDIOF_PRETIMEOUT,
>>>   };
>>>
>>>   static int imx2_restart_handler(struct notifier_block *this, unsigned long mode,
>>> @@ -207,12 +215,49 @@ static inline void imx2_wdt_ping_if_active(struct watchdog_device *wdog)
>>>   	}
>>>   }
>>>
>>> +static int imx2_wdt_set_pretimeout(struct watchdog_device *wdog,
>>> +				   unsigned int new_timeout)
>>> +{
>>> +	struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
>>> +	u32 val;
>>> +
>>> +	regmap_read(wdev->regmap, IMX2_WDT_WICR, &val);
>>> +	/* set the new pre-timeout value in the WSR */
>>> +	val &= ~IMX2_WDT_WICR_WICT;
>>> +	val |= WDOG_SEC_TO_PRECOUNT(new_timeout);
>>
>> Looking into this, I think we need more information in the first patch.
>> Specifically, we need a value for max_pretimeout and validate it
>> (new_timeout must be smaller than 128 to avoid overflows, independent
>> of the maximum timeout).
>>
> I think it's enough, since there is "t >= wdd->timeout" in
> watchdog_pretimeout_invalid() of the first patch and wdd->timeout is never
> bigger than wdd->max_timeout which setting in imx2_wdt.c as 128.

We are dealing with infrastructure code here. This happens to work for your driver,
but that doesn't mean it will work for other drivers.

Anyway, I recalled that there is another patchset pending to add pretimeout
support into the watchdog code. I'll have to dig that out and consolidate the two.

Guenter

>>> +
>>> +	regmap_write(wdev->regmap, IMX2_WDT_WICR, val | IMX2_WDT_WICR_WIE);
>>> +
>>> +	wdog->pretimeout = new_timeout;
>>> +
>>> +	return 0;
>>> +}
>>> +
>>> +static irqreturn_t imx2_wdt_isr(int irq, void *dev_id)
>>> +{
>>> +	struct platform_device *pdev = dev_id;
>>> +	struct watchdog_device *wdog = platform_get_drvdata(pdev);
>>> +	struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
>>> +	u32 val;
>>> +
>>> +	regmap_read(wdev->regmap, IMX2_WDT_WICR, &val);
>>> +	if (val & IMX2_WDT_WICR_WTIS) {
>>> +		/*clear interrupt status bit*/
>>> +		regmap_write(wdev->regmap, IMX2_WDT_WICR, val);
>>> +		panic("pre-timeout:%d, %d Seconds remained\n", wdog->pretimeout,
>>
>> "seconds" - no capital 'S'.
>>
>>> +		      wdog->timeout - wdog->pretimeout);
>>> +	}
>>> +
>>> +	return IRQ_HANDLED;
>>> +}
>>> +
>>>   static const struct watchdog_ops imx2_wdt_ops = {
>>>   	.owner = THIS_MODULE,
>>>   	.start = imx2_wdt_start,
>>>   	.stop = imx2_wdt_stop,
>>>   	.ping = imx2_wdt_ping,
>>>   	.set_timeout = imx2_wdt_set_timeout,
>>> +	.set_pretimeout = imx2_wdt_set_pretimeout,
>>>   };
>>>
>>>   static const struct regmap_config imx2_wdt_regmap_config = {
>>> @@ -229,6 +274,7 @@ static int __init imx2_wdt_probe(struct platform_device *pdev)
>>>   	struct resource *res;
>>>   	void __iomem *base;
>>>   	int ret;
>>> +	int irq;
>>>   	u32 val;
>>>
>>>   	wdev = devm_kzalloc(&pdev->dev, sizeof(*wdev), GFP_KERNEL);
>>> @@ -294,6 +340,16 @@ static int __init imx2_wdt_probe(struct platform_device *pdev)
>>>   		goto disable_clk;
>>>   	}
>>>
>>> +	irq = platform_get_irq(pdev, 0);
>>> +	if (irq > 0) {
>>> +		ret = devm_request_irq(&pdev->dev, irq, imx2_wdt_isr, 0,
>>> +				       dev_name(&pdev->dev), pdev);
>>> +		if (ret) {
>>> +			dev_err(&pdev->dev, "can't get irq %d\n", irq);
>>> +			goto disable_clk;
>>> +		}
>>> +	}
>>> +
>>>   	wdev->restart_handler.notifier_call = imx2_restart_handler;
>>>   	wdev->restart_handler.priority = 128;
>>>   	ret = register_restart_handler(&wdev->restart_handler);
>>>
>>
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