On Thu, Nov 05, 2015 at 04:19:21PM -0500, Akshay Bhat wrote: > From: Tim Harvey <tharvey@xxxxxxxxxxxxx> > > 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@xxxxxxxxxxxxxx> > Signed-off-by: Tim Harvey <tharvey@xxxxxxxxxxxxx> > --- > .../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: 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. > +- ext-reset-output: If present the watchdog device is configured to assert its Should that have a vendor prefix ? Also, not sure if "-output" has any real value in the property name. "fsl,external-reset", maybe ? > + 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 29ef719..84bfec4 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, IMX2_WDT_WCR, 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; I don't really understand what this means. Normally I would hope that a watchdog only generates a reset if/when it times out. > /* 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", > -- > 2.6.2 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-watchdog" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
