Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752703AbdCDQDd (ORCPT ); Sat, 4 Mar 2017 11:03:33 -0500 Received: from bh-25.webhostbox.net ([208.91.199.152]:46869 "EHLO bh-25.webhostbox.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752690AbdCDQDb (ORCPT ); Sat, 4 Mar 2017 11:03:31 -0500 Subject: Re: [PATCH 1/4] watchdog: sama5d4: fix WDDIS handling To: Alexandre Belloni References: <20170302173114.28508-1-alexandre.belloni@free-electrons.com> <20170302173114.28508-2-alexandre.belloni@free-electrons.com> Cc: Wim Van Sebroeck , Nicolas Ferre , Wenyou.Yang@microchip.com, linux-watchdog@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org From: Guenter Roeck Message-ID: <75caf7fe-8922-cd7e-897f-59cb763c1583@roeck-us.net> Date: Sat, 4 Mar 2017 07:04:58 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.5.1 MIME-Version: 1.0 In-Reply-To: <20170302173114.28508-2-alexandre.belloni@free-electrons.com> 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 Content-Length: 3865 Lines: 116 On 03/02/2017 09:31 AM, Alexandre Belloni wrote: > The datasheet states: "When setting the WDDIS bit, and while it is set, the > fields WDV and WDD must not be modified." > > Because the whole configuration is already cached inside .mr, wait for the > user to enable the watchdog to configure it so it is enabled and configured > at the same time (what the IP is actually expecting). > > When the watchdog is already enabled, it is not an issue to reconfigure it. > > Signed-off-by: Alexandre Belloni Reviewed-by: Guenter Roeck > --- > drivers/watchdog/sama5d4_wdt.c | 48 ++++++++++++++++++++++++++---------------- > 1 file changed, 30 insertions(+), 18 deletions(-) > > diff --git a/drivers/watchdog/sama5d4_wdt.c b/drivers/watchdog/sama5d4_wdt.c > index f709962018ac..5cee20caca78 100644 > --- a/drivers/watchdog/sama5d4_wdt.c > +++ b/drivers/watchdog/sama5d4_wdt.c > @@ -44,6 +44,8 @@ MODULE_PARM_DESC(nowayout, > "Watchdog cannot be stopped once started (default=" > __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); > > +#define wdt_enabled (!(wdt->mr & AT91_WDT_WDDIS)) > + > #define wdt_read(wdt, field) \ > readl_relaxed((wdt)->reg_base + (field)) > > @@ -89,7 +91,16 @@ static int sama5d4_wdt_set_timeout(struct watchdog_device *wdd, > wdt->mr &= ~AT91_WDT_WDD; > wdt->mr |= AT91_WDT_SET_WDV(value); > wdt->mr |= AT91_WDT_SET_WDD(value); > - wdt_write(wdt, AT91_WDT_MR, wdt->mr); > + > + /* > + * WDDIS has to be 0 when updating WDD/WDV. The datasheet states: When > + * setting the WDDIS bit, and while it is set, the fields WDV and WDD > + * must not be modified. > + * If the watchdog is enabled, then the timeout can be updated. Else, > + * wait that the user enables it. > + */ > + if (wdt_enabled) > + wdt_write(wdt, AT91_WDT_MR, wdt->mr & ~AT91_WDT_WDDIS); > > wdd->timeout = timeout; > > @@ -145,23 +156,20 @@ static int of_sama5d4_wdt_init(struct device_node *np, struct sama5d4_wdt *wdt) > > static int sama5d4_wdt_init(struct sama5d4_wdt *wdt) > { > - struct watchdog_device *wdd = &wdt->wdd; > - u32 value = WDT_SEC2TICKS(wdd->timeout); > u32 reg; > - > /* > - * Because the fields WDV and WDD must not be modified when the WDDIS > - * bit is set, so clear the WDDIS bit before writing the WDT_MR. > + * When booting and resuming, the bootloader may have changed the > + * watchdog configuration. > + * If the watchdog is already running, we can safely update it. > + * Else, we have to disable it properly. > */ > - reg = wdt_read(wdt, AT91_WDT_MR); > - reg &= ~AT91_WDT_WDDIS; > - wdt_write(wdt, AT91_WDT_MR, reg); > - > - wdt->mr |= AT91_WDT_SET_WDD(value); > - wdt->mr |= AT91_WDT_SET_WDV(value); > - > - wdt_write(wdt, AT91_WDT_MR, wdt->mr); > - > + if (wdt_enabled) { > + wdt_write(wdt, AT91_WDT_MR, wdt->mr); > + } else { > + reg = wdt_read(wdt, AT91_WDT_MR); > + if (!(reg & AT91_WDT_WDDIS)) > + wdt_write(wdt, AT91_WDT_MR, reg | AT91_WDT_WDDIS); > + } > return 0; > } > > @@ -172,6 +180,7 @@ static int sama5d4_wdt_probe(struct platform_device *pdev) > struct resource *res; > void __iomem *regs; > u32 irq = 0; > + u32 timeout; > int ret; > > wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL); > @@ -221,6 +230,11 @@ static int sama5d4_wdt_probe(struct platform_device *pdev) > return ret; > } > > + timeout = WDT_SEC2TICKS(wdd->timeout); > + > + wdt->mr |= AT91_WDT_SET_WDD(timeout); > + wdt->mr |= AT91_WDT_SET_WDV(timeout); > + > ret = sama5d4_wdt_init(wdt); > if (ret) > return ret; > @@ -263,9 +277,7 @@ static int sama5d4_wdt_resume(struct device *dev) > { > struct sama5d4_wdt *wdt = dev_get_drvdata(dev); > > - wdt_write(wdt, AT91_WDT_MR, wdt->mr & ~AT91_WDT_WDDIS); > - if (wdt->mr & AT91_WDT_WDDIS) > - wdt_write(wdt, AT91_WDT_MR, wdt->mr); > + sama5d4_wdt_init(wdt); > > return 0; > } >