From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752774AbcGONqm (ORCPT ); Fri, 15 Jul 2016 09:46:42 -0400 Received: from bh-25.webhostbox.net ([208.91.199.152]:54963 "EHLO bh-25.webhostbox.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751915AbcGONqk (ORCPT ); Fri, 15 Jul 2016 09:46:40 -0400 Subject: Re: [PATCH 3/3] watchdog: bcm2835_wdt: set WDOG_HW_RUNNING bit when appropriate To: Rasmus Villemoes , Wim Van Sebroeck , Stephen Warren , Lee Jones , Eric Anholt References: <1468570524-18222-1-git-send-email-rasmus.villemoes@prevas.dk> <1468570524-18222-3-git-send-email-rasmus.villemoes@prevas.dk> Cc: linux-watchdog@vger.kernel.org, linux-rpi-kernel@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org From: Guenter Roeck Message-ID: <5788E935.6080608@roeck-us.net> Date: Fri, 15 Jul 2016 06:46:29 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.8.0 MIME-Version: 1.0 In-Reply-To: <1468570524-18222-3-git-send-email-rasmus.villemoes@prevas.dk> Content-Type: text/plain; charset=windows-1252; 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-Authenticated-Sender: bh-25.webhostbox.net: 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 On 07/15/2016 01:15 AM, Rasmus Villemoes wrote: > A bootloader may start the watchdog device before handing control to > the kernel - in that case, we should tell the kernel about it so the > watchdog framework can keep it alive until userspace opens > /dev/watchdog0. > Separate note: The maximum timeout for this watchdog is 15 seconds. Given that, it might be useful to set max_hw_heartbeat_ms instead of max_timeout. Separate patch, though. > Signed-off-by: Rasmus Villemoes > --- > drivers/watchdog/bcm2835_wdt.c | 22 ++++++++++++++++++++++ > 1 file changed, 22 insertions(+) > > diff --git a/drivers/watchdog/bcm2835_wdt.c b/drivers/watchdog/bcm2835_wdt.c > index 4dddd82..9a08334 100644 > --- a/drivers/watchdog/bcm2835_wdt.c > +++ b/drivers/watchdog/bcm2835_wdt.c > @@ -55,6 +55,15 @@ struct bcm2835_wdt { > static unsigned int heartbeat; > static bool nowayout = WATCHDOG_NOWAYOUT; > > +static bool bcm2835_wdt_is_running(struct bcm2835_wdt *wdt) > +{ > + uint32_t cur; > + > + cur = readl(wdt->base + PM_RSTC); > + > + return !!(cur & PM_RSTC_WRCFG_FULL_RESET); > +} > + > static int bcm2835_wdt_start(struct watchdog_device *wdog) > { > struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog); > @@ -70,6 +79,7 @@ static int bcm2835_wdt_start(struct watchdog_device *wdog) > PM_RSTC_WRCFG_FULL_RESET, wdt->base + PM_RSTC); > > spin_unlock_irqrestore(&wdt->lock, flags); > + set_bit(WDOG_HW_RUNNING, &wdog->status); > You don't need to set this bit here unless the watchdog can not be stopped. > return 0; > } > @@ -79,6 +89,7 @@ static int bcm2835_wdt_stop(struct watchdog_device *wdog) > struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog); > > writel_relaxed(PM_PASSWORD | PM_RSTC_RESET, wdt->base + PM_RSTC); > + clear_bit(WDOG_HW_RUNNING, &wdog->status); ... and since you clear the bit, it can be stopped. Both setting and resetting the bit is therefore not necessary. > return 0; > } > > @@ -181,6 +192,17 @@ static int bcm2835_wdt_probe(struct platform_device *pdev) > watchdog_init_timeout(&bcm2835_wdt_wdd, heartbeat, dev); > watchdog_set_nowayout(&bcm2835_wdt_wdd, nowayout); > bcm2835_wdt_wdd.parent = &pdev->dev; > + if (bcm2835_wdt_is_running(wdt)) { > + /* > + * The currently active timeout value (set by the > + * bootloader) may be different from the module > + * heartbeat parameter or the value in device > + * tree. But we just need to set WDOG_HW_RUNNING, > + * because then the framework will "immediately" ping > + * the device, updating the timeout. > + */ > + set_bit(WDOG_HW_RUNNING, &bcm2835_wdt_wdd.status); > + } > err = watchdog_register_device(&bcm2835_wdt_wdd); > if (err) { > dev_err(dev, "Failed to register watchdog device"); >