| Message ID | 1438097230-2653-2-git-send-email-tharvey@gateworks.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Tue, Jul 28, 2015 at 08:27:09AM -0700, 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 '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: Lucas Stach <l.stach@pengutronix.de> > Signed-off-by: Tim Harvey <tharvey@gateworks.com> Acked-by: Shawn Guo <shawnguo@kernel.org>
On Tue, Jul 28, 2015 at 8:27 AM, Tim Harvey <tharvey@gateworks.com> 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 '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: Lucas Stach <l.stach@pengutronix.de> > Signed-off-by: Tim Harvey <tharvey@gateworks.com> > --- > 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 <tharvey@gateworks.com> > --- > .../devicetree/bindings/watchdog/fsl-imx-wdt.txt | 2 ++ > drivers/watchdog/imx2_wdt.c | 20 ++++++++++++++++++-- > 2 files changed, 20 insertions(+), 2 deletions(-) > > diff --git a/Documentation/devicetree/bindings/watchdog/fsl-imx-wdt.txt b/Documentation/devicetree/bindings/watchdog/fsl-imx-wdt.txt > index 8dab6fd..9b89b3a 100644 > --- a/Documentation/devicetree/bindings/watchdog/fsl-imx-wdt.txt > +++ b/Documentation/devicetree/bindings/watchdog/fsl-imx-wdt.txt > @@ -9,6 +9,8 @@ Optional property: > - 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. > +- 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 0bb1a1d..5d9ccf6 100644 > --- a/drivers/watchdog/imx2_wdt.c > +++ b/drivers/watchdog/imx2_wdt.c > @@ -41,6 +41,8 @@ > > #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 */ > @@ -65,6 +67,7 @@ struct imx2_wdt_device { > struct timer_list timer; /* Pings the watchdog when closed */ > struct watchdog_device wdog; > struct notifier_block restart_handler; > + bool ext_reset; > }; > > static bool nowayout = WATCHDOG_NOWAYOUT; > @@ -90,6 +93,13 @@ static int imx2_restart_handler(struct notifier_block *this, unsigned long mode, > struct imx2_wdt_device *wdev = container_of(this, > struct imx2_wdt_device, > restart_handler); > + > + /* 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, 0, wcr_enable); > /* > @@ -119,8 +129,12 @@ 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 */ > @@ -267,6 +281,8 @@ 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, > + "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", > -- > 1.9.1 > Wim, I believe I missed sending this to the proper watchdog maintainer which appears to be you. Regards, Tim
diff --git a/Documentation/devicetree/bindings/watchdog/fsl-imx-wdt.txt b/Documentation/devicetree/bindings/watchdog/fsl-imx-wdt.txt index 8dab6fd..9b89b3a 100644 --- a/Documentation/devicetree/bindings/watchdog/fsl-imx-wdt.txt +++ b/Documentation/devicetree/bindings/watchdog/fsl-imx-wdt.txt @@ -9,6 +9,8 @@ Optional property: - 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. +- 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 0bb1a1d..5d9ccf6 100644 --- a/drivers/watchdog/imx2_wdt.c +++ b/drivers/watchdog/imx2_wdt.c @@ -41,6 +41,8 @@ #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 */ @@ -65,6 +67,7 @@ struct imx2_wdt_device { struct timer_list timer; /* Pings the watchdog when closed */ struct watchdog_device wdog; struct notifier_block restart_handler; + bool ext_reset; }; static bool nowayout = WATCHDOG_NOWAYOUT; @@ -90,6 +93,13 @@ static int imx2_restart_handler(struct notifier_block *this, unsigned long mode, struct imx2_wdt_device *wdev = container_of(this, struct imx2_wdt_device, restart_handler); + + /* 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, 0, wcr_enable); /* @@ -119,8 +129,12 @@ 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 */ @@ -267,6 +281,8 @@ 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, + "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",