From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from bh-25.webhostbox.net ([208.91.199.152]:40747 "EHLO bh-25.webhostbox.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752530AbcDHBJx (ORCPT ); Thu, 7 Apr 2016 21:09:53 -0400 Subject: Re: [PATCH v5 1/2] watchdog: imx2_wdt: add external reset support via dt prop To: Tim Harvey , linux-watchdog@vger.kernel.org, Shawn Guo References: <1459523804-11390-1-git-send-email-tharvey@gateworks.com> <1459523804-11390-2-git-send-email-tharvey@gateworks.com> Cc: linux-arm-kernel@lists.infradead.org, Fabio Estevam , Lucas Stach , Akshay Bhat , Wim Van Sebroeck , Stefan Roese , Iain Paton , Sascha Hauer From: Guenter Roeck Message-ID: <570704E1.6010700@roeck-us.net> Date: Thu, 7 Apr 2016 18:09:53 -0700 MIME-Version: 1.0 In-Reply-To: <1459523804-11390-2-git-send-email-tharvey@gateworks.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-watchdog-owner@vger.kernel.org List-Id: linux-watchdog@vger.kernel.org On 04/01/2016 08:16 AM, Tim Harvey wrote: > The IMX6 watchdog supports assertion of a signal (WDOG_B) which > can be pinmux'd to an external pin. This is typically used for boards that > have PMIC's in control of the IMX6 power rails. In fact, failure to use > such an external reset on boards with external PMIC's can result in various > hangs due to the IMX6 not being fully reset [1] as well as the board failing > to reset because its PMIC has not been reset to provide adequate voltage for > the CPU when coming out of reset at 800Mhz. > > This uses a new device-tree property 'fsl,ext-reset-output' to indicate the > board has such a reset and to cause the watchdog to be configured to assert > WDOG_B instead of an internal reset both on a watchdog timeout and in > system_restart. > > [1] http://lists.infradead.org/pipermail/linux-arm-kernel/2015-March/333689.html > > Cc: Fabio Estevam > Cc: Lucas Stach > Cc: Stefan Roese > Cc: Iain Paton > Cc: Sascha Hauer > Cc: Akshay Bhat > Cc: Guenter Roeck > Signed-off-by: Tim Harvey > Reviewed-by: Lucas Stach > Acked-by: Shawn Guo Reviewed-by: Guenter Roeck > --- > v5: > - rename property to 'fsl,ext-reset-output' > v4: > - change Property to Properties in documentation > v3: > - mandate use of 'either' internal or external reset but not both > simultaneously > v2: > - rename property to 'ext-reset-output' based on ML feedback > - simplify setting SRS bit if external-reset > - update comments and commit msg > > Signed-off-by: Tim Harvey > --- > .../devicetree/bindings/watchdog/fsl-imx-wdt.txt | 4 +++- > drivers/watchdog/imx2_wdt.c | 19 +++++++++++++++++-- > 2 files changed, 20 insertions(+), 3 deletions(-) > > diff --git a/Documentation/devicetree/bindings/watchdog/fsl-imx-wdt.txt b/Documentation/devicetree/bindings/watchdog/fsl-imx-wdt.txt > index 8dab6fd..107280e 100644 > --- a/Documentation/devicetree/bindings/watchdog/fsl-imx-wdt.txt > +++ b/Documentation/devicetree/bindings/watchdog/fsl-imx-wdt.txt > @@ -5,10 +5,12 @@ Required properties: > - reg : Should contain WDT registers location and length > - interrupts : Should contain WDT interrupt > > -Optional property: > +Optional properties: > - big-endian: If present the watchdog device's registers are implemented > in big endian mode, otherwise in native mode(same with CPU), for more > detail please see: Documentation/devicetree/bindings/regmap/regmap.txt. > +- fsl,ext-reset-output: If present the watchdog device is configured to > + assert its external reset (WDOG_B) instead of issuing a software reset. > > Examples: > > diff --git a/drivers/watchdog/imx2_wdt.c b/drivers/watchdog/imx2_wdt.c > index e47966a..cb838be 100644 > --- a/drivers/watchdog/imx2_wdt.c > +++ b/drivers/watchdog/imx2_wdt.c > @@ -39,6 +39,8 @@ > > #define IMX2_WDT_WCR 0x00 /* Control Register */ > #define IMX2_WDT_WCR_WT (0xFF << 8) /* -> Watchdog Timeout Field */ > +#define IMX2_WDT_WCR_WDA (1 << 5) /* -> External Reset WDOG_B */ > +#define IMX2_WDT_WCR_SRS (1 << 4) /* -> Software Reset Signal */ > #define IMX2_WDT_WCR_WRE (1 << 3) /* -> WDOG Reset Enable */ > #define IMX2_WDT_WCR_WDE (1 << 2) /* -> Watchdog Enable */ > #define IMX2_WDT_WCR_WDZST (1 << 0) /* -> Watchdog timer Suspend */ > @@ -62,6 +64,7 @@ struct imx2_wdt_device { > struct regmap *regmap; > struct timer_list timer; /* Pings the watchdog when closed */ > struct watchdog_device wdog; > + bool ext_reset; > }; > > static bool nowayout = WATCHDOG_NOWAYOUT; > @@ -85,6 +88,12 @@ static int imx2_wdt_restart(struct watchdog_device *wdog) > struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog); > unsigned int wcr_enable = IMX2_WDT_WCR_WDE; > > + /* Use internal reset or external - not both */ > + if (wdev->ext_reset) > + wcr_enable |= IMX2_WDT_WCR_SRS; /* do not assert int reset */ > + else > + wcr_enable |= IMX2_WDT_WCR_WDA; /* do not assert ext-reset */ > + > /* Assert SRS signal */ > regmap_write(wdev->regmap, IMX2_WDT_WCR, wcr_enable); > /* > @@ -114,8 +123,12 @@ static inline void imx2_wdt_setup(struct watchdog_device *wdog) > val |= IMX2_WDT_WCR_WDZST; > /* Strip the old watchdog Time-Out value */ > val &= ~IMX2_WDT_WCR_WT; > - /* Generate reset if WDOG times out */ > - val &= ~IMX2_WDT_WCR_WRE; > + /* Generate internal chip-level reset if WDOG times out */ > + if (!wdev->ext_reset) > + val &= ~IMX2_WDT_WCR_WRE; > + /* Or if external-reset assert WDOG_B reset only on time-out */ > + else > + val |= IMX2_WDT_WCR_WRE; > /* Keep Watchdog Disabled */ > val &= ~IMX2_WDT_WCR_WDE; > /* Set the watchdog's Time-Out value */ > @@ -263,6 +276,8 @@ static int __init imx2_wdt_probe(struct platform_device *pdev) > regmap_read(wdev->regmap, IMX2_WDT_WRSR, &val); > wdog->bootstatus = val & IMX2_WDT_WRSR_TOUT ? WDIOF_CARDRESET : 0; > > + wdev->ext_reset = of_property_read_bool(pdev->dev.of_node, > + "fsl,ext-reset-output"); > wdog->timeout = clamp_t(unsigned, timeout, 1, IMX2_WDT_MAX_TIME); > if (wdog->timeout != timeout) > dev_warn(&pdev->dev, "Initial timeout out of range! Clamped from %u to %u\n", > From mboxrd@z Thu Jan 1 00:00:00 1970 From: linux@roeck-us.net (Guenter Roeck) Date: Thu, 7 Apr 2016 18:09:53 -0700 Subject: [PATCH v5 1/2] watchdog: imx2_wdt: add external reset support via dt prop In-Reply-To: <1459523804-11390-2-git-send-email-tharvey@gateworks.com> References: <1459523804-11390-1-git-send-email-tharvey@gateworks.com> <1459523804-11390-2-git-send-email-tharvey@gateworks.com> Message-ID: <570704E1.6010700@roeck-us.net> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 04/01/2016 08:16 AM, Tim Harvey wrote: > The IMX6 watchdog supports assertion of a signal (WDOG_B) which > can be pinmux'd to an external pin. This is typically used for boards that > have PMIC's in control of the IMX6 power rails. In fact, failure to use > such an external reset on boards with external PMIC's can result in various > hangs due to the IMX6 not being fully reset [1] as well as the board failing > to reset because its PMIC has not been reset to provide adequate voltage for > the CPU when coming out of reset at 800Mhz. > > This uses a new device-tree property 'fsl,ext-reset-output' to indicate the > board has such a reset and to cause the watchdog to be configured to assert > WDOG_B instead of an internal reset both on a watchdog timeout and in > system_restart. > > [1] http://lists.infradead.org/pipermail/linux-arm-kernel/2015-March/333689.html > > Cc: Fabio Estevam > Cc: Lucas Stach > Cc: Stefan Roese > Cc: Iain Paton > Cc: Sascha Hauer > Cc: Akshay Bhat > Cc: Guenter Roeck > Signed-off-by: Tim Harvey > Reviewed-by: Lucas Stach > Acked-by: Shawn Guo Reviewed-by: Guenter Roeck > --- > v5: > - rename property to 'fsl,ext-reset-output' > v4: > - change Property to Properties in documentation > v3: > - mandate use of 'either' internal or external reset but not both > simultaneously > v2: > - rename property to 'ext-reset-output' based on ML feedback > - simplify setting SRS bit if external-reset > - update comments and commit msg > > Signed-off-by: Tim Harvey > --- > .../devicetree/bindings/watchdog/fsl-imx-wdt.txt | 4 +++- > drivers/watchdog/imx2_wdt.c | 19 +++++++++++++++++-- > 2 files changed, 20 insertions(+), 3 deletions(-) > > diff --git a/Documentation/devicetree/bindings/watchdog/fsl-imx-wdt.txt b/Documentation/devicetree/bindings/watchdog/fsl-imx-wdt.txt > index 8dab6fd..107280e 100644 > --- a/Documentation/devicetree/bindings/watchdog/fsl-imx-wdt.txt > +++ b/Documentation/devicetree/bindings/watchdog/fsl-imx-wdt.txt > @@ -5,10 +5,12 @@ Required properties: > - reg : Should contain WDT registers location and length > - interrupts : Should contain WDT interrupt > > -Optional property: > +Optional properties: > - big-endian: If present the watchdog device's registers are implemented > in big endian mode, otherwise in native mode(same with CPU), for more > detail please see: Documentation/devicetree/bindings/regmap/regmap.txt. > +- fsl,ext-reset-output: If present the watchdog device is configured to > + assert its external reset (WDOG_B) instead of issuing a software reset. > > Examples: > > diff --git a/drivers/watchdog/imx2_wdt.c b/drivers/watchdog/imx2_wdt.c > index e47966a..cb838be 100644 > --- a/drivers/watchdog/imx2_wdt.c > +++ b/drivers/watchdog/imx2_wdt.c > @@ -39,6 +39,8 @@ > > #define IMX2_WDT_WCR 0x00 /* Control Register */ > #define IMX2_WDT_WCR_WT (0xFF << 8) /* -> Watchdog Timeout Field */ > +#define IMX2_WDT_WCR_WDA (1 << 5) /* -> External Reset WDOG_B */ > +#define IMX2_WDT_WCR_SRS (1 << 4) /* -> Software Reset Signal */ > #define IMX2_WDT_WCR_WRE (1 << 3) /* -> WDOG Reset Enable */ > #define IMX2_WDT_WCR_WDE (1 << 2) /* -> Watchdog Enable */ > #define IMX2_WDT_WCR_WDZST (1 << 0) /* -> Watchdog timer Suspend */ > @@ -62,6 +64,7 @@ struct imx2_wdt_device { > struct regmap *regmap; > struct timer_list timer; /* Pings the watchdog when closed */ > struct watchdog_device wdog; > + bool ext_reset; > }; > > static bool nowayout = WATCHDOG_NOWAYOUT; > @@ -85,6 +88,12 @@ static int imx2_wdt_restart(struct watchdog_device *wdog) > struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog); > unsigned int wcr_enable = IMX2_WDT_WCR_WDE; > > + /* Use internal reset or external - not both */ > + if (wdev->ext_reset) > + wcr_enable |= IMX2_WDT_WCR_SRS; /* do not assert int reset */ > + else > + wcr_enable |= IMX2_WDT_WCR_WDA; /* do not assert ext-reset */ > + > /* Assert SRS signal */ > regmap_write(wdev->regmap, IMX2_WDT_WCR, wcr_enable); > /* > @@ -114,8 +123,12 @@ static inline void imx2_wdt_setup(struct watchdog_device *wdog) > val |= IMX2_WDT_WCR_WDZST; > /* Strip the old watchdog Time-Out value */ > val &= ~IMX2_WDT_WCR_WT; > - /* Generate reset if WDOG times out */ > - val &= ~IMX2_WDT_WCR_WRE; > + /* Generate internal chip-level reset if WDOG times out */ > + if (!wdev->ext_reset) > + val &= ~IMX2_WDT_WCR_WRE; > + /* Or if external-reset assert WDOG_B reset only on time-out */ > + else > + val |= IMX2_WDT_WCR_WRE; > /* Keep Watchdog Disabled */ > val &= ~IMX2_WDT_WCR_WDE; > /* Set the watchdog's Time-Out value */ > @@ -263,6 +276,8 @@ static int __init imx2_wdt_probe(struct platform_device *pdev) > regmap_read(wdev->regmap, IMX2_WDT_WRSR, &val); > wdog->bootstatus = val & IMX2_WDT_WRSR_TOUT ? WDIOF_CARDRESET : 0; > > + wdev->ext_reset = of_property_read_bool(pdev->dev.of_node, > + "fsl,ext-reset-output"); > wdog->timeout = clamp_t(unsigned, timeout, 1, IMX2_WDT_MAX_TIME); > if (wdog->timeout != timeout) > dev_warn(&pdev->dev, "Initial timeout out of range! Clamped from %u to %u\n", >