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

[Robin Gong <b38343@freescale.com>]

On Tue, Nov 03, 2015 at 09:26:16AM -0800, Guenter Roeck wrote:
> 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
>
Got it. Thanks.
> >>>+
> >>>+	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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