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Message-ID: <20151103045501.GB26305@shlinux2>
Date: Tue, 3 Nov 2015 12:55:02 +0800
From: Robin Gong <b38343@...escale.com>
To: Guenter Roeck <linux@...ck-us.net>
CC: <wim@...ana.be>, <linux-watchdog@...r.kernel.org>,
<linux-kernel@...r.kernel.org>,
<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v1 2/2] watchdog: imx2_wdt: add set_pretimeout interface
On Mon, Nov 02, 2015 at 08:19:12PM -0800, Guenter Roeck wrote:
> On 11/02/2015 07:29 PM, Robin Gong wrote:
> >Enable set_pretimeout interface and trigger the pretimeout interrupt before
> >watchdog timeout event happen.
> >
> >Signed-off-by: Robin Gong <b38343@...escale.com>
> >---
> > drivers/watchdog/imx2_wdt.c | 67 ++++++++++++++++++++++++++++++++++++++++++++-
> > 1 file changed, 66 insertions(+), 1 deletion(-)
> >
> >diff --git a/drivers/watchdog/imx2_wdt.c b/drivers/watchdog/imx2_wdt.c
> >index 0bb1a1d..d3c6b07 100644
> >--- a/drivers/watchdog/imx2_wdt.c
> >+++ b/drivers/watchdog/imx2_wdt.c
> >@@ -24,7 +24,9 @@
> > #include <linux/clk.h>
> > #include <linux/delay.h>
> > #include <linux/init.h>
> >+#include <linux/interrupt.h>
> > #include <linux/io.h>
> >+#include <linux/irq.h>
>
> Are those two new includes both needed ?
>
Yes, irq.h is not needed.
> > #include <linux/jiffies.h>
> > #include <linux/kernel.h>
> > #include <linux/module.h>
> >@@ -52,12 +54,18 @@
> > #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 << 0) /* Watchdog Interrupt Timeout */
> >+
>
> "<< 0" doesn't really add any value here.
>
Accept.
> > #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*/
> >
> ((s) * 2)
>
> Ah yes, WDOG_SEC_TO_COUNT should also use (s).
>
> > struct imx2_wdt_device {
> > struct clk *clk;
> >@@ -80,7 +88,8 @@ 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 +216,59 @@ static inline void imx2_wdt_ping_if_active(struct watchdog_device *wdog)
> > }
> > }
> >
> >+static int imx2_wdt_check_pretimeout_set(struct imx2_wdt_device *wdev)
> >+{
> >+ u32 val;
> >+
> >+ regmap_read(wdev->regmap, IMX2_WDT_WICR, &val);
> >+ return (val & IMX2_WDT_WICR_WIE) ? 1 : 0;
>
> I don't understand the point of this function.
> You check if IMX2_WDT_WICR_WIE is set,
>
Yes, looks no need check,just directly set this bit.
> >+}
> >+
> >+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);
> >+
>
> What is the time here ? Is pretimeout the number of seconds
> until the interrupt occurs, or the number of seconds before the actual
> timeout (as per API) ?
>
The latter is.
> >+ if (!imx2_wdt_check_pretimeout_set(wdev))
> >+ val |= IMX2_WDT_WICR_WIE; /*enable*/
>
> if IMX2_WDT_WICR_WIE is not set, you set it,
>
> >+
> >+ regmap_write(wdev->regmap, IMX2_WDT_WICR, val);
> >+
>
> and write the result unconditionally. Unless I am missing something,
>
> regmap_write, wdev->regmap, IMX2_WDT_WICR, val | IMX2_WDT_WICR_WIE);
>
> would accomplish exactly the same.
>
> >+ 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);
> >+ dev_warn(&pdev->dev, "pre-timeout:%d, %d Seconds remained\n",
> >+ wdog->pretimeout, wdog->timeout - wdog->pretimeout);
>
> The idea here is that this should trigger a panic.
>
Just add a print message, our customer will add what they want here.
> >+ }
> >+ 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 +285,7 @@ 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);
> >@@ -253,6 +310,14 @@ static int __init imx2_wdt_probe(struct platform_device *pdev)
> > return PTR_ERR(wdev->clk);
> > }
> >
> >+ irq = platform_get_irq(pdev, 0);
>
> This makes the irq mandatory. What if a platform doesn't have one configured ?
>
> >+ 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);
>
> You got it, but you could not request it.
>
> This is also a bit early, as the interrupt handler uses variables which are not yet
> initialized.
>
Accept.
> >+ return ret;
> >+ }
> >+
> > wdog = &wdev->wdog;
> > wdog->info = &imx2_wdt_info;
> > wdog->ops = &imx2_wdt_ops;
> >
>
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