On Fri, Nov 22, 2019 at 02:22:46PM +0100, Christophe Roullier wrote:
> If the watchdog hardware is already enabled during the boot process,
> when the Linux watchdog driver loads, it should start/reset the watchdog
> and tell the watchdog framework. As a result, ping can be generated from
> the watchdog framework (if CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED is set),
> until the userspace watchdog daemon takes over control
>
> Fixes:4332d113c66a ("watchdog: Add STM32 IWDG driver")
>
> Signed-off-by: Christophe Roullier <christophe.roullier@xxxxxx>
Reviewed-by: Guenter Roeck <linux@xxxxxxxxxxxx>
> ---
> Changes since v2:
> According to Guenter
> removed intermediate variable
>
> I've tested some config and it is working as expected:
> Watchdog enable in Uboot + HANDLE_BOOT_ENABLE is not set + daemon watchdog in userland ON ==> No reset IWDG2
> Watchdog enable in Uboot + HANDLE_BOOT_ENABLE is not set ==> Reset IWDG2
> Watchdog enable in Uboot + HANDLE_BOOT_ENABLE=y ==> No reset IWDG2
> Watchdog enable in Uboot + HANDLE_BOOT_ENABLE=y + daemon watchdog in userland ON puis OFF ==> Reset IWDG2
> Watchdog disable in Uboot + HANDLE_BOOT_ENABLE is not set ==> No reset IWDG2
> Watchdog disable in Uboot + HANDLE_BOOT_ENABLE=y ==> No reset IWDG2
> Watchdog disable in Uboot + HANDLE_BOOT_ENABLE=y + daemon watchdog in userland ON ==> No reset IWDG2
> Watchdog disable in Uboot + HANDLE_BOOT_ENABLE=y + daemon watchdog in userland ON puis OFF ==> Reset IWDG2
>
> Thanks,
> Christophe
>
> drivers/watchdog/stm32_iwdg.c | 18 ++++++++++++++++++
> 1 file changed, 18 insertions(+)
>
> diff --git a/drivers/watchdog/stm32_iwdg.c b/drivers/watchdog/stm32_iwdg.c
> index a3a329011a06..25188d6bbe15 100644
> --- a/drivers/watchdog/stm32_iwdg.c
> +++ b/drivers/watchdog/stm32_iwdg.c
> @@ -262,6 +262,24 @@ static int stm32_iwdg_probe(struct platform_device *pdev)
> watchdog_set_nowayout(wdd, WATCHDOG_NOWAYOUT);
> watchdog_init_timeout(wdd, 0, dev);
>
> + /*
> + * In case of CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED is set
> + * (Means U-Boot/bootloaders leaves the watchdog running)
> + * When we get here we should make a decision to prevent
> + * any side effects before user space daemon will take care of it.
> + * The best option, taking into consideration that there is no
> + * way to read values back from hardware, is to enforce watchdog
> + * being run with deterministic values.
> + */
> + if (IS_ENABLED(CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED)) {
> + ret = stm32_iwdg_start(wdd);
> + if (ret)
> + return ret;
> +
> + /* Make sure the watchdog is serviced */
> + set_bit(WDOG_HW_RUNNING, &wdd->status);
> + }
> +
> ret = devm_watchdog_register_device(dev, wdd);
> if (ret)
> return ret;
> --
> 2.17.1
>
