| Message ID | 1446758362-11702-2-git-send-email-akshay.bhat@timesys.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Thu, Nov 05, 2015 at 04:19:21PM -0500, Akshay Bhat wrote: > From: Tim Harvey <tharvey@gateworks.com> > > 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> > --- > .../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@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html
On Thu, Nov 5, 2015 at 2:23 PM, Guenter Roeck <linux@roeck-us.net> wrote: > On Thu, Nov 05, 2015 at 04:19:21PM -0500, Akshay Bhat wrote: >> From: Tim Harvey <tharvey@gateworks.com> >> >> 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> >> --- >> .../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 ? Hi Guenter, I don't see why a vendor prefix is necessary - its a feature of the IMX6 watchdog supported by this driver to be able to trigger an internal chip-level reset and/or an external signal that can be hooked to additional hardware. I started with ext-reset, but it was suggested (http://lists.infradead.org/pipermail/linux-arm-kernel/2015-May/347437.html) to also make it clear that this is an 'output' and not a reset input. > >> + 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. I think we went a couple of rounds on the info in the comment as well in the previous patch reversions. It is a feature of the IMX6 watchdog supported by this driver to be able to trigger an internal chip-level reset and/or an external signal that can be hooked to additional hardware. In the case of using a PMIC that can regulate it's own rails (ie the Freescale SabreSD reference design) an SoC chip-level reset will not reset the PMIC and thus if the PMIC's rails have been driven down by DVFS to a value below the necessary value for the chip to come up you will hang (which is certainly not what you want to do when a watchdog timeout occurs). The solution for designs that have a PMIC that is able to change its voltage levels is to 'not' have the SoC internally reset and to 'instead' drive an external reset signal that should reset the PMIC (and possibly other chips if needed). The reason for not allowing the internal reset is because as soon as the SoC goes into reset it de-asserts the external reset which makes the time the output is asserted un-deterministic. Tim
On Fri, Nov 06, 2015 at 11:53:42AM -0800, Tim Harvey wrote: > On Thu, Nov 5, 2015 at 2:23 PM, Guenter Roeck <linux@roeck-us.net> wrote: > > On Thu, Nov 05, 2015 at 04:19:21PM -0500, Akshay Bhat wrote: > >> From: Tim Harvey <tharvey@gateworks.com> > >> > >> 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> > >> --- > >> .../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 ? > > Hi Guenter, > > I don't see why a vendor prefix is necessary - its a feature of the > IMX6 watchdog supported by this driver to be able to trigger an > internal chip-level reset and/or an external signal that can be hooked > to additional hardware. > Sounded like vendor specific to me, but then I am not a devicetree maintainer, so I am not an authority on the subject. > I started with ext-reset, but it was suggested > (http://lists.infradead.org/pipermail/linux-arm-kernel/2015-May/347437.html) > to also make it clear that this is an 'output' and not a reset input. > No problem, as long as you get an Ack from a devicetree maintainer. Guenter
On 11/06/2015 05:02 PM, Guenter Roeck wrote: > On Fri, Nov 06, 2015 at 11:53:42AM -0800, Tim Harvey wrote: >> On Thu, Nov 5, 2015 at 2:23 PM, Guenter Roeck <linux@roeck-us.net> wrote: >>> On Thu, Nov 05, 2015 at 04:19:21PM -0500, Akshay Bhat wrote: >>>> From: Tim Harvey <tharvey@gateworks.com> >>>> >>>> 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> >>>> --- >>>> .../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 ? >> >> Hi Guenter, >> >> I don't see why a vendor prefix is necessary - its a feature of the >> IMX6 watchdog supported by this driver to be able to trigger an >> internal chip-level reset and/or an external signal that can be hooked >> to additional hardware. >> > Sounded like vendor specific to me, but then I am not a devicetree maintainer, > so I am not an authority on the subject. Devicetree maintainers, Any thoughts? Tim, After looking at all the other watchdog drivers, it does not appear that there is any other processor which uses a similar feature. Since imx is the only processor that appears to support this feature, it might make sense in making this vendor specific. If in the future it is found more processors support a similar functionality, it can be revisited and moved out from being vendor specific? > >> I started with ext-reset, but it was suggested >> (http://lists.infradead.org/pipermail/linux-arm-kernel/2015-May/347437.html) >> to also make it clear that this is an 'output' and not a reset input. >> > No problem, as long as you get an Ack from a devicetree maintainer. > > Guenter >
On Wed, Dec 2, 2015 at 11:11 AM, Akshay Bhat <akshay.bhat@timesys.com> wrote: > > > On 11/06/2015 05:02 PM, Guenter Roeck wrote: >> >> On Fri, Nov 06, 2015 at 11:53:42AM -0800, Tim Harvey wrote: >>> >>> On Thu, Nov 5, 2015 at 2:23 PM, Guenter Roeck <linux@roeck-us.net> wrote: >>>> >>>> On Thu, Nov 05, 2015 at 04:19:21PM -0500, Akshay Bhat wrote: >>>>> >>>>> From: Tim Harvey <tharvey@gateworks.com> >>>>> >>>>> 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> >>>>> --- >>>>> .../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 ? >>> >>> >>> Hi Guenter, >>> >>> I don't see why a vendor prefix is necessary - its a feature of the >>> IMX6 watchdog supported by this driver to be able to trigger an >>> internal chip-level reset and/or an external signal that can be hooked >>> to additional hardware. >>> >> Sounded like vendor specific to me, but then I am not a devicetree >> maintainer, >> so I am not an authority on the subject. > > > Devicetree maintainers, > > Any thoughts? > > Tim, > > After looking at all the other watchdog drivers, it does not appear that > there is any other processor which uses a similar feature. Since imx is the > only processor that appears to support this feature, it might make sense in > making this vendor specific. If in the future it is found more processors > support a similar functionality, it can be revisited and moved out from > being vendor specific? > I'm certainly no expert on device-tree policy. I understand your point, but realize that the driver in question is imx2_wdt.c (compatible = "fsl,imx21-wdt"). This is an IP block inside the silicon of only Freescale chips, so its not like a future omap chip would be using this driver - only fsl devices. So why would it need a 'vendor' property any more than its other properties? Regards, Tim
On Wed, Dec 2, 2015 at 12:54 PM, Tim Harvey <tharvey@gateworks.com> wrote: > > On Wed, Dec 2, 2015 at 11:11 AM, Akshay Bhat <akshay.bhat@timesys.com> wrote: > > > > > > On 11/06/2015 05:02 PM, Guenter Roeck wrote: > >> > >> On Fri, Nov 06, 2015 at 11:53:42AM -0800, Tim Harvey wrote: > >>> > >>> On Thu, Nov 5, 2015 at 2:23 PM, Guenter Roeck <linux@roeck-us.net> wrote: > >>>> > >>>> On Thu, Nov 05, 2015 at 04:19:21PM -0500, Akshay Bhat wrote: > >>>>> > >>>>> From: Tim Harvey <tharvey@gateworks.com> > >>>>> > >>>>> 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> > >>>>> --- > >>>>> .../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 ? > >>> > >>> > >>> Hi Guenter, > >>> > >>> I don't see why a vendor prefix is necessary - its a feature of the > >>> IMX6 watchdog supported by this driver to be able to trigger an > >>> internal chip-level reset and/or an external signal that can be hooked > >>> to additional hardware. > >>> > >> Sounded like vendor specific to me, but then I am not a devicetree > >> maintainer, > >> so I am not an authority on the subject. > > > > > > Devicetree maintainers, > > > > Any thoughts? > > > > Tim, > > > > After looking at all the other watchdog drivers, it does not appear that > > there is any other processor which uses a similar feature. Since imx is the > > only processor that appears to support this feature, it might make sense in > > making this vendor specific. If in the future it is found more processors > > support a similar functionality, it can be revisited and moved out from > > being vendor specific? > > > > I'm certainly no expert on device-tree policy. I understand your > point, but realize that the driver in question is imx2_wdt.c > (compatible = "fsl,imx21-wdt"). This is an IP block inside the silicon > of only Freescale chips, so its not like a future omap chip would be > using this driver - only fsl devices. So why would it need a 'vendor' > property any more than its other properties? > > Regards, > > Tim Wim, Does the lack of response mean overwhelming approval? I haven't heard any valid complaints - what does it take to get this approved? Regards, Tim
On 12/17/2015 07:02 AM, Tim Harvey wrote: > On Wed, Dec 2, 2015 at 12:54 PM, Tim Harvey <tharvey@gateworks.com> wrote: >> >> On Wed, Dec 2, 2015 at 11:11 AM, Akshay Bhat <akshay.bhat@timesys.com> wrote: >>> >>> >>> On 11/06/2015 05:02 PM, Guenter Roeck wrote: >>>> >>>> On Fri, Nov 06, 2015 at 11:53:42AM -0800, Tim Harvey wrote: >>>>> >>>>> On Thu, Nov 5, 2015 at 2:23 PM, Guenter Roeck <linux@roeck-us.net> wrote: >>>>>> >>>>>> On Thu, Nov 05, 2015 at 04:19:21PM -0500, Akshay Bhat wrote: >>>>>>> >>>>>>> From: Tim Harvey <tharvey@gateworks.com> >>>>>>> >>>>>>> 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> >>>>>>> --- >>>>>>> .../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 ? >>>>> >>>>> >>>>> Hi Guenter, >>>>> >>>>> I don't see why a vendor prefix is necessary - its a feature of the >>>>> IMX6 watchdog supported by this driver to be able to trigger an >>>>> internal chip-level reset and/or an external signal that can be hooked >>>>> to additional hardware. >>>>> >>>> Sounded like vendor specific to me, but then I am not a devicetree >>>> maintainer, >>>> so I am not an authority on the subject. >>> >>> >>> Devicetree maintainers, >>> >>> Any thoughts? >>> >>> Tim, >>> >>> After looking at all the other watchdog drivers, it does not appear that >>> there is any other processor which uses a similar feature. Since imx is the >>> only processor that appears to support this feature, it might make sense in >>> making this vendor specific. If in the future it is found more processors >>> support a similar functionality, it can be revisited and moved out from >>> being vendor specific? >>> >> >> I'm certainly no expert on device-tree policy. I understand your >> point, but realize that the driver in question is imx2_wdt.c >> (compatible = "fsl,imx21-wdt"). This is an IP block inside the silicon >> of only Freescale chips, so its not like a future omap chip would be >> using this driver - only fsl devices. So why would it need a 'vendor' >> property any more than its other properties? >> >> Regards, >> >> Tim > > Wim, > > Does the lack of response mean overwhelming approval? > > I haven't heard any valid complaints - what does it take to get this approved? > Tim, Do you have an Ack from a devicetree maintainer ? I don't recall seeing one. Thanks, Guenter
Rob, On 12/28/2015 11:29 AM, Wim Van Sebroeck wrote: > Hi Tim, > >> On Wed, Dec 2, 2015 at 12:54 PM, Tim Harvey <tharvey@gateworks.com> wrote: >>> >>> On Wed, Dec 2, 2015 at 11:11 AM, Akshay Bhat <akshay.bhat@timesys.com> wrote: >>>> >>>> >>>> On 11/06/2015 05:02 PM, Guenter Roeck wrote: >>>>> >>>>> On Fri, Nov 06, 2015 at 11:53:42AM -0800, Tim Harvey wrote: >>>>>> >>>>>> On Thu, Nov 5, 2015 at 2:23 PM, Guenter Roeck <linux@roeck-us.net> wrote: >>>>>>> >>>>>>> On Thu, Nov 05, 2015 at 04:19:21PM -0500, Akshay Bhat wrote: >>>>>>>> >>>>>>>> From: Tim Harvey <tharvey@gateworks.com> >>>>>>>> >>>>>>>> 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> >>>>>>>> --- >>>>>>>> .../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 ? >>>>>> >>>>>> >>>>>> Hi Guenter, >>>>>> >>>>>> I don't see why a vendor prefix is necessary - its a feature of the >>>>>> IMX6 watchdog supported by this driver to be able to trigger an >>>>>> internal chip-level reset and/or an external signal that can be hooked >>>>>> to additional hardware. >>>>>> >>>>> Sounded like vendor specific to me, but then I am not a devicetree >>>>> maintainer, >>>>> so I am not an authority on the subject. >>>> >>>> >>>> Devicetree maintainers, >>>> >>>> Any thoughts? >>>> >>>> Tim, >>>> >>>> After looking at all the other watchdog drivers, it does not appear that >>>> there is any other processor which uses a similar feature. Since imx is the >>>> only processor that appears to support this feature, it might make sense in >>>> making this vendor specific. If in the future it is found more processors >>>> support a similar functionality, it can be revisited and moved out from >>>> being vendor specific? >>>> >>> >>> I'm certainly no expert on device-tree policy. I understand your >>> point, but realize that the driver in question is imx2_wdt.c >>> (compatible = "fsl,imx21-wdt"). This is an IP block inside the silicon >>> of only Freescale chips, so its not like a future omap chip would be >>> using this driver - only fsl devices. So why would it need a 'vendor' >>> property any more than its other properties? >>> >>> Regards, >>> >>> Tim >> >> Wim, >> >> Does the lack of response mean overwhelming approval? >> >> I haven't heard any valid complaints - what does it take to get this approved? >> >> Regards, >> >> Tim > > I have no objections against the idea and the code itself. > But as Guenter pointed out: it would be handy to get feedback from the devicetree maintainers on the above discussion. > > Kind regards, > Wim. > Any suggestions on whether a vendor specific prefix is necessary? Thanks, Akshay
Rob, On Thu, Jan 28, 2016 at 6:28 PM, Akshay Bhat <akshay.bhat@timesys.com> wrote: >> I have no objections against the idea and the code itself. >> But as Guenter pointed out: it would be handy to get feedback from the >> devicetree maintainers on the above discussion. >> >> Kind regards, >> Wim. >> > > Any suggestions on whether a vendor specific prefix is necessary? Any comments?
Hi Shawn, On 02/28/2016 08:56 AM, Fabio Estevam wrote: > Rob, > > On Thu, Jan 28, 2016 at 6:28 PM, Akshay Bhat <akshay.bhat@timesys.com> wrote: > >>> I have no objections against the idea and the code itself. >>> But as Guenter pointed out: it would be handy to get feedback from the >>> devicetree maintainers on the above discussion. >>> >>> Kind regards, >>> Wim. >>> >> >> Any suggestions on whether a vendor specific prefix is necessary? > > Any comments? > Is this something you can help with, since you are the iMX architecture/devicetree maintainer? Appreciate any feedback. Thanks, Akshay
On Mon, Mar 28, 2016 at 04:19:15PM -0400, Akshay Bhat wrote: > Hi Shawn, > > On 02/28/2016 08:56 AM, Fabio Estevam wrote: > >Rob, > > > >On Thu, Jan 28, 2016 at 6:28 PM, Akshay Bhat <akshay.bhat@timesys.com> wrote: > > > >>>I have no objections against the idea and the code itself. > >>>But as Guenter pointed out: it would be handy to get feedback from the > >>>devicetree maintainers on the above discussion. > >>> > >>>Kind regards, > >>>Wim. > >>> > >> > >>Any suggestions on whether a vendor specific prefix is necessary? > > > >Any comments? > > > > Is this something you can help with, since you are the iMX > architecture/devicetree maintainer? Appreciate any feedback. FWIW, Acked-by: Shawn Guo <shawnguo@kernel.org> Guenter, I think it's reasonable to pick up the patch, if we have it copied to DT maintainers and on the list for a long period of time, and do not see any objection from anyone. Shawn
On Wed, Mar 30, 2016 at 09:22:33AM +0800, Shawn Guo wrote: > On Mon, Mar 28, 2016 at 04:19:15PM -0400, Akshay Bhat wrote: > > Hi Shawn, > > > > On 02/28/2016 08:56 AM, Fabio Estevam wrote: > > >Rob, > > > > > >On Thu, Jan 28, 2016 at 6:28 PM, Akshay Bhat <akshay.bhat@timesys.com> wrote: > > > > > >>>I have no objections against the idea and the code itself. > > >>>But as Guenter pointed out: it would be handy to get feedback from the > > >>>devicetree maintainers on the above discussion. > > >>> > > >>>Kind regards, > > >>>Wim. > > >>> > > >> > > >>Any suggestions on whether a vendor specific prefix is necessary? > > > > > >Any comments? > > > > > > > Is this something you can help with, since you are the iMX > > architecture/devicetree maintainer? Appreciate any feedback. > > FWIW, > > Acked-by: Shawn Guo <shawnguo@kernel.org> > > Guenter, > > I think it's reasonable to pick up the patch, if we have it copied to DT > maintainers and on the list for a long period of time, and do not see > any objection from anyone. > The question was if the property name should be ext-reset-output or fsl,ext-reset-output. In my opinion, it should be fsl,ext-reset-output because it is not a generic property. Tim disagrees. So we have two options: Change the property name to fsl,ext-reset-output, which I would accept, or wait for a devicetree maintainer to make a decision. Guenter
On Wed, Mar 30, 2016 at 02:09:16PM -0700, Guenter Roeck wrote: > The question was if the property name should be ext-reset-output or > fsl,ext-reset-output. In my opinion, it should be fsl,ext-reset-output > because it is not a generic property. Tim disagrees. > > So we have two options: Change the property name to fsl,ext-reset-output, > which I would accept, or wait for a devicetree maintainer to make a decision. Guenter, I agree with you on this point. Before everyone agrees that this is a generic binding, we should have vendor prefix for the property. Tim, This is a small change which, IMO, shouldn't hold an useful patch from being merged. Care to resend with the suggested change? Shawn
On Wed, Mar 30, 2016 at 6:57 PM, Shawn Guo <shawnguo@kernel.org> wrote: > On Wed, Mar 30, 2016 at 02:09:16PM -0700, Guenter Roeck wrote: >> The question was if the property name should be ext-reset-output or >> fsl,ext-reset-output. In my opinion, it should be fsl,ext-reset-output >> because it is not a generic property. Tim disagrees. >> Guenter, My issue regarding the vendor prefix was not a hard dissagreement but was more about me understanding the rational behind using vendor prefixes. In this case the imx2_wdt driver 'is' a vendor specific driver as its compatible strings are prefixed with 'fsl,' so isn't 'any' property added to devicetree/bindings/watchdog/fsl-imx-wdt.txt inherently a vendor specific properly already? I assume that is why the 'big-endian' property isn't 'fsl,big-endian'. Maybe it's more about if it 'is' marked as a vendor specific property its much easier to get approval and accepted by a vendor-specific maintainer? >> So we have two options: Change the property name to fsl,ext-reset-output, >> which I would accept, or wait for a devicetree maintainer to make a decision. > > Guenter, > > I agree with you on this point. Before everyone agrees that this is a > generic binding, we should have vendor prefix for the property. > > Tim, > > This is a small change which, IMO, shouldn't hold an useful patch from being > merged. Care to resend with the suggested change? > > Shawn Shawn, Sure - I'll rebase and re-submit. Tim
On Thu, Mar 31, 2016 at 11:01:58AM -0700, Tim Harvey wrote: > On Wed, Mar 30, 2016 at 6:57 PM, Shawn Guo <shawnguo@kernel.org> wrote: > > On Wed, Mar 30, 2016 at 02:09:16PM -0700, Guenter Roeck wrote: > >> The question was if the property name should be ext-reset-output or > >> fsl,ext-reset-output. In my opinion, it should be fsl,ext-reset-output > >> because it is not a generic property. Tim disagrees. > >> > > Guenter, > > My issue regarding the vendor prefix was not a hard dissagreement but > was more about me understanding the rational behind using vendor > prefixes. In this case the imx2_wdt driver 'is' a vendor specific > driver as its compatible strings are prefixed with 'fsl,' so isn't > 'any' property added to devicetree/bindings/watchdog/fsl-imx-wdt.txt > inherently a vendor specific properly already? I assume that is why > the 'big-endian' property isn't 'fsl,big-endian'. We should read it as that 'big-endian' is a generic property defined by generic bindings - bindings/regmap/regmap.txt, and we just reference the bindings in fsl-imx-wdt.txt. Taking mmc bindings as example, bindings/mmc/mmc.txt defines generic bindings, while bindings/mmc/fsl-imx-esdhc.txt defines i.MX vendor specific properties, which should ideally have vendor prefix. Shawn
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 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; /* 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",