From mboxrd@z Thu Jan 1 00:00:00 1970 From: l.stach@pengutronix.de (Lucas Stach) Date: Fri, 29 May 2015 18:37:38 +0200 Subject: [PATCH 1/2] watchdog: imx2_wdt: add external reset support via 'ext-reset' dt property In-Reply-To: <1432853677-5150-2-git-send-email-tharvey@gateworks.com> References: <1432853677-5150-1-git-send-email-tharvey@gateworks.com> <1432853677-5150-2-git-send-email-tharvey@gateworks.com> Message-ID: <1432917458.3015.10.camel@pengutronix.de> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Am Donnerstag, den 28.05.2015, 15:54 -0700 schrieb Tim Harvey: > 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 voltate for > the CPU when comming out of reset at 800Mhz. > > This uses a new device-tree property 'ext-reset' 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 > > Signed-off-by: Tim Harvey > --- > .../devicetree/bindings/watchdog/fsl-imx-wdt.txt | 2 ++ > drivers/watchdog/imx2_wdt.c | 18 ++++++++++++++++-- > 2 files changed, 18 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..14e04ac 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: If present the watchdog device is configured to assert its > + external reset (WDOG_B) instead of issuing a software reset. > Probably a bit of personal taste, but I would prefer the naming to include the property that this is a output. So something like "ext-reset-output". > Examples: > > diff --git a/drivers/watchdog/imx2_wdt.c b/drivers/watchdog/imx2_wdt.c > index 5e6d808..9ffd516 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 Assert */ > +#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; > @@ -86,10 +89,17 @@ static const struct watchdog_info imx2_wdt_info = { > static int imx2_restart_handler(struct notifier_block *this, unsigned long mode, > void *cmd) > { > - unsigned int wcr_enable = IMX2_WDT_WCR_WDE; > + unsigned int wcr_enable; > struct imx2_wdt_device *wdev = container_of(this, > struct imx2_wdt_device, > restart_handler); > + > + if (!wdev->ext_reset) > + wcr_enable = IMX2_WDT_WCR_WDE; > + /* Use external reset */ > + else > + wcr_enable = IMX2_WDT_WCR_WDE | IMX2_WDT_WCR_SRS; > + This doesn't look nice. Please write this simply as: if (wdev->ext_reset) wcr_enable |= IMX2_WDT_WCR_SRS; > /* Assert SRS signal */ > regmap_write(wdev->regmap, 0, wcr_enable); > /* > @@ -120,7 +130,10 @@ static inline void imx2_wdt_setup(struct watchdog_device *wdog) > /* Strip the old watchdog Time-Out value */ > val &= ~IMX2_WDT_WCR_WT; > /* Generate reset if WDOG times out */ > - val &= ~IMX2_WDT_WCR_WRE; > + if (!wdev->ext_reset) > + val &= ~IMX2_WDT_WCR_WRE; > + else > + val |= IMX2_WDT_WCR_WRE; /* assert WDOG_B on time-out */ The comment above this sections doesn't seem to match the code anymore after your change. > /* Keep Watchdog Disabled */ > val &= ~IMX2_WDT_WCR_WDE; > /* Set the watchdog's Time-Out value */ > @@ -262,6 +275,7 @@ 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"); > 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", -- Pengutronix e.K. | Lucas Stach | Industrial Linux Solutions | http://www.pengutronix.de/ |