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Date: Tue, 24 Nov 2015 18:51:00 -0800 From: Guenter Roeck <linux@...ck-us.net> To: Simon Arlott <simon@...e.lp0.eu>, linux-watchdog@...r.kernel.org Cc: "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>, Ralf Baechle <ralf@...ux-mips.org>, Thomas Gleixner <tglx@...utronix.de>, Jason Cooper <jason@...edaemon.net>, Marc Zyngier <marc.zyngier@....com>, Kevin Cernekee <cernekee@...il.com>, Florian Fainelli <f.fainelli@...il.com>, Wim Van Sebroeck <wim@...ana.be>, Maxime Bizon <mbizon@...ebox.fr>, Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, linux-mips@...ux-mips.org, Rob Herring <robh+dt@...nel.org>, Pawel Moll <pawel.moll@....com>, Mark Rutland <mark.rutland@....com>, Ian Campbell <ijc+devicetree@...lion.org.uk>, Kumar Gala <galak@...eaurora.org>, Jonas Gorski <jogo@...nwrt.org> Subject: Re: [PATCH (v2) 7/10] watchdog: bcm63xx_wdt: Add get_timeleft function On 11/24/2015 02:15 PM, Simon Arlott wrote: > Return the remaining time from the hardware control register. > > Warn when the device is registered if the hardware watchdog is currently > running and report the remaining time left. This is really two logical changes, isn't it ? Nice trick to figure out if the watchdog is running. What is the impact ? Will this result in interrupts ? If so, would it make sense to _not_ reset the system after a timeout in this case, but to keep pinging the watchdog while the watchdog device is not open ? Thanks, Guenter > > Signed-off-by: Simon Arlott <simon@...e.lp0.eu> > --- > Changed "if (timeleft > 0)" to "if (hw->running)" when checking if a > warning should be printed, in case the time left is truncated down to > 0 seconds. > > drivers/watchdog/bcm63xx_wdt.c | 37 +++++++++++++++++++++++++++++++++++++ > 1 file changed, 37 insertions(+) > > diff --git a/drivers/watchdog/bcm63xx_wdt.c b/drivers/watchdog/bcm63xx_wdt.c > index 3c7667a..9d099e0 100644 > --- a/drivers/watchdog/bcm63xx_wdt.c > +++ b/drivers/watchdog/bcm63xx_wdt.c > @@ -14,6 +14,7 @@ > #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt > > #include <linux/clk.h> > +#include <linux/delay.h> > #include <linux/errno.h> > #include <linux/io.h> > #include <linux/kernel.h> > @@ -75,6 +76,19 @@ static int bcm63xx_wdt_stop(struct watchdog_device *wdd) > return 0; > } > > +static unsigned int bcm63xx_wdt_get_timeleft(struct watchdog_device *wdd) > +{ > + struct bcm63xx_wdt_hw *hw = watchdog_get_drvdata(wdd); > + unsigned long flags; > + u32 val; > + > + raw_spin_lock_irqsave(&hw->lock, flags); > + val = __raw_readl(hw->regs + WDT_CTL_REG); > + val /= hw->clock_hz; > + raw_spin_unlock_irqrestore(&hw->lock, flags); > + return val; > +} > + > static int bcm63xx_wdt_set_timeout(struct watchdog_device *wdd, > unsigned int timeout) > { > @@ -130,6 +144,7 @@ static struct watchdog_ops bcm63xx_wdt_ops = { > .owner = THIS_MODULE, > .start = bcm63xx_wdt_start, > .stop = bcm63xx_wdt_stop, > + .get_timeleft = bcm63xx_wdt_get_timeleft, > .set_timeout = bcm63xx_wdt_set_timeout, > }; > > @@ -144,6 +159,8 @@ static int bcm63xx_wdt_probe(struct platform_device *pdev) > struct bcm63xx_wdt_hw *hw; > struct watchdog_device *wdd; > struct resource *r; > + u32 timeleft1, timeleft2; > + unsigned int timeleft; > int ret; > > hw = devm_kzalloc(&pdev->dev, sizeof(*hw), GFP_KERNEL); > @@ -197,6 +214,23 @@ static int bcm63xx_wdt_probe(struct platform_device *pdev) > watchdog_init_timeout(wdd, 0, &pdev->dev); > watchdog_set_nowayout(wdd, nowayout); > > + /* Compare two reads of the time left value, 2 clock ticks apart */ > + rmb(); > + timeleft1 = __raw_readl(hw->regs + WDT_CTL_REG); > + udelay(DIV_ROUND_UP(1000000, hw->clock_hz / 2)); > + /* Ensure the register is read twice */ > + rmb(); > + timeleft2 = __raw_readl(hw->regs + WDT_CTL_REG); > + > + /* If the time left is changing, the watchdog is running */ > + if (timeleft1 != timeleft2) { > + hw->running = true; > + timeleft = bcm63xx_wdt_get_timeleft(wdd); > + } else { > + hw->running = false; > + timeleft = 0; > + } > + > ret = bcm63xx_timer_register(TIMER_WDT_ID, bcm63xx_wdt_isr, wdd); > if (ret < 0) { > dev_err(&pdev->dev, "failed to register wdt timer isr\n"); > @@ -214,6 +248,8 @@ static int bcm63xx_wdt_probe(struct platform_device *pdev) > dev_name(wdd->dev), hw->regs, > wdd->timeout, wdd->max_timeout); > > + if (hw->running) > + dev_alert(wdd->dev, "running, reboot in %us\n", timeleft); > return 0; > > unregister_timer: > @@ -255,6 +291,7 @@ module_platform_driver(bcm63xx_wdt_driver); > > MODULE_AUTHOR("Miguel Gaio <miguel.gaio@...xo.com>"); > MODULE_AUTHOR("Florian Fainelli <florian@...nwrt.org>"); > +MODULE_AUTHOR("Simon Arlott"); > MODULE_DESCRIPTION("Driver for the Broadcom BCM63xx SoC watchdog"); > MODULE_LICENSE("GPL"); > MODULE_ALIAS("platform:bcm63xx-wdt"); > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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