Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755375AbbKYCvM (ORCPT ); Tue, 24 Nov 2015 21:51:12 -0500 Received: from bh-25.webhostbox.net ([208.91.199.152]:59814 "EHLO bh-25.webhostbox.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754488AbbKYCvH (ORCPT ); Tue, 24 Nov 2015 21:51:07 -0500 Subject: Re: [PATCH (v2) 7/10] watchdog: bcm63xx_wdt: Add get_timeleft function To: Simon Arlott , linux-watchdog@vger.kernel.org References: <5650BFD6.5030700@simon.arlott.org.uk> <5650C08C.6090300@simon.arlott.org.uk> <5650E2FA.6090408@roeck-us.net> <5650E5BB.6020404@simon.arlott.org.uk> <56512937.6030903@roeck-us.net> <5651CB13.4090704@simon.arlott.org.uk> <5651CC90.7090402@simon.arlott.org.uk> Cc: "devicetree@vger.kernel.org" , Ralf Baechle , Thomas Gleixner , Jason Cooper , Marc Zyngier , Kevin Cernekee , Florian Fainelli , Wim Van Sebroeck , Maxime Bizon , Linux Kernel Mailing List , linux-mips@linux-mips.org, Rob Herring , Pawel Moll , Mark Rutland , Ian Campbell , Kumar Gala , Jonas Gorski From: Guenter Roeck Message-ID: <56552214.2050808@roeck-us.net> Date: Tue, 24 Nov 2015 18:51:00 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.3.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit X-Authenticated_sender: linux@roeck-us.net X-OutGoing-Spam-Status: No, score=-1.0 X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - bh-25.webhostbox.net X-AntiAbuse: Original Domain - vger.kernel.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - roeck-us.net X-Get-Message-Sender-Via: bh-25.webhostbox.net: authenticated_id: linux@roeck-us.net X-Source: X-Source-Args: X-Source-Dir: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4199 Lines: 125 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 > --- > 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 > +#include > #include > #include > #include > @@ -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 "); > MODULE_AUTHOR("Florian Fainelli "); > +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@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/