[PATCH 1/2] watchdog: imx2_wdt: add external reset support via 'ext-reset' dt property
Lucas Stach
l.stach at pengutronix.de
Fri May 29 09:37:38 PDT 2015
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 <tharvey at gateworks.com>
> ---
> .../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/ |
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