From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751843AbaIYSlz (ORCPT ); Thu, 25 Sep 2014 14:41:55 -0400 Received: from mail-pd0-f169.google.com ([209.85.192.169]:42309 "EHLO mail-pd0-f169.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751020AbaIYSly (ORCPT ); Thu, 25 Sep 2014 14:41:54 -0400 Date: Thu, 25 Sep 2014 11:41:49 -0700 From: Guenter Roeck To: Josh Cartwright Cc: Wim Van Sebroeck , linux-watchdog@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Kumar Gala , linux-kernel@vger.kernel.org Subject: Re: [PATCH v3 3/3] watchdog: qcom: register a restart notifier Message-ID: <20140925184149.GB12340@roeck-us.net> References: <2dc54244e755eeacf8265a484819e0c2e2393221.1411667144.git.joshc@codeaurora.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2dc54244e755eeacf8265a484819e0c2e2393221.1411667144.git.joshc@codeaurora.org> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Sep 25, 2014 at 12:48:53PM -0500, Josh Cartwright wrote: > The WDT's BITE_TIME warm-reset behavior can be leveraged as a last > resort mechanism for triggering chip reset. Usually, other restart > methods (such as PS_HOLD) are preferrable for issuing a more complete > reset of the chip. As such, keep the priority of the watchdog notifier > low. > > Signed-off-by: Josh Cartwright > --- > drivers/watchdog/qcom-wdt.c | 38 ++++++++++++++++++++++++++++++++++++++ > 1 file changed, 38 insertions(+) > > diff --git a/drivers/watchdog/qcom-wdt.c b/drivers/watchdog/qcom-wdt.c > index 0f56ca3..8ce339f 100644 > --- a/drivers/watchdog/qcom-wdt.c > +++ b/drivers/watchdog/qcom-wdt.c > @@ -10,12 +10,14 @@ > * GNU General Public License for more details. > * > */ > +#include Nitpick: Please keep alphabetical order of include files. That makes it easier to identify include files later on. > #include > #include > #include > #include > #include > #include > +#include > #include > > #define WDT_RST 0x0 > @@ -26,6 +28,7 @@ struct qcom_wdt { > struct watchdog_device wdd; > struct clk *clk; > unsigned long rate; > + struct notifier_block restart_nb; > void __iomem *base; > }; > > @@ -84,6 +87,32 @@ static const struct watchdog_info qcom_wdt_info = { > .identity = KBUILD_MODNAME, > }; > > +static int qcom_wdt_restart(struct notifier_block *nb, unsigned long action, > + void *data) > +{ > + struct qcom_wdt *wdt = container_of(nb, struct qcom_wdt, restart_nb); > + u32 timeout; > + > + /* > + * Trigger watchdog bite: > + * Setup BITE_TIME to be 128ms, and enable WDT. > + */ > + timeout = 128 * wdt->rate / 1000; > + > + writel(0, wdt->base + WDT_EN); > + writel(1, wdt->base + WDT_RST); > + writel(timeout, wdt->base + WDT_BITE_TIME); > + writel(1, wdt->base + WDT_EN); > + > + /* > + * Actually make sure the above sequence hits hardware before sleeping. > + */ > + wmb(); > + > + msleep(150); > + return NOTIFY_DONE; > +} > + > static int qcom_wdt_probe(struct platform_device *pdev) > { > struct qcom_wdt *wdt; > @@ -149,6 +178,14 @@ static int qcom_wdt_probe(struct platform_device *pdev) > goto err_clk_unprepare; > } > > + /* > + * WDT restart notifier has priority 0 (use as a last resort) > + */ > + wdt->restart_nb.notifier_call = qcom_wdt_restart; > + ret = register_restart_handler(&wdt->restart_nb); > + if (ret) > + dev_err(&pdev->dev, "failed to setup restart handler\n"); > + > platform_set_drvdata(pdev, wdt); > return 0; > > @@ -162,6 +199,7 @@ static int qcom_wdt_remove(struct platform_device *pdev) > { > struct qcom_wdt *wdt = platform_get_drvdata(pdev); > > + unregister_restart_handler(&wdt->restart_nb); > watchdog_unregister_device(&wdt->wdd); > clk_disable_unprepare(wdt->clk); > return 0; > -- > Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, > hosted by The Linux Foundation >