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SubjectRe: [PATCH v3 4/6] watchdog: sp805: set WDOG_HW_RUNNING when appropriate
On Wed, May 23, 2018 at 05:15:22PM -0700, Ray Jui wrote:
> If the watchdog hardware is already enabled during the boot process,
> when the Linux watchdog driver loads, it should reset the watchdog and
> tell the watchdog framework. As a result, ping can be generated from
> the watchdog framework, until the userspace watchdog daemon takes over
> control
>
> Signed-off-by: Ray Jui <ray.jui@broadcom.com>
> Reviewed-by: Vladimir Olovyannikov <vladimir.olovyannikov@broadcom.com>
> Reviewed-by: Scott Branden <scott.branden@broadcom.com>

Reviewed-by: Guenter Roeck <linux@roeck-us.net>

I have one question, though: Is it really correct that both
INT_ENABLE _and_ RESET_ENABLE have to be set to enable the watdog ?
What if only RESET_ENABLE is set ?

Thanks,
Guenter

> ---
> drivers/watchdog/sp805_wdt.c | 19 +++++++++++++++++++
> 1 file changed, 19 insertions(+)
>
> diff --git a/drivers/watchdog/sp805_wdt.c b/drivers/watchdog/sp805_wdt.c
> index 1484609..d662a6f 100644
> --- a/drivers/watchdog/sp805_wdt.c
> +++ b/drivers/watchdog/sp805_wdt.c
> @@ -42,6 +42,7 @@
> /* control register masks */
> #define INT_ENABLE (1 << 0)
> #define RESET_ENABLE (1 << 1)
> + #define ENABLE_MASK (INT_ENABLE | RESET_ENABLE)
> #define WDTINTCLR 0x00C
> #define WDTRIS 0x010
> #define WDTMIS 0x014
> @@ -74,6 +75,15 @@ module_param(nowayout, bool, 0);
> MODULE_PARM_DESC(nowayout,
> "Set to 1 to keep watchdog running after device release");
>
> +/* returns true if wdt is running; otherwise returns false */
> +static bool wdt_is_running(struct watchdog_device *wdd)
> +{
> + struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
> + u32 wdtcontrol = readl_relaxed(wdt->base + WDTCONTROL);
> +
> + return (wdtcontrol & ENABLE_MASK) == ENABLE_MASK;
> +}
> +
> /* This routine finds load value that will reset system in required timout */
> static int wdt_setload(struct watchdog_device *wdd, unsigned int timeout)
> {
> @@ -239,6 +249,15 @@ sp805_wdt_probe(struct amba_device *adev, const struct amba_id *id)
> watchdog_init_timeout(&wdt->wdd, 0, &adev->dev);
> wdt_setload(&wdt->wdd, wdt->wdd.timeout);
>
> + /*
> + * If HW is already running, enable/reset the wdt and set the running
> + * bit to tell the wdt subsystem
> + */
> + if (wdt_is_running(&wdt->wdd)) {
> + wdt_enable(&wdt->wdd);
> + set_bit(WDOG_HW_RUNNING, &wdt->wdd.status);
> + }
> +
> ret = watchdog_register_device(&wdt->wdd);
> if (ret) {
> dev_err(&adev->dev, "watchdog_register_device() failed: %d\n",
> --
> 2.1.4
>
> --
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