On 7/17/20 6:29 AM, Tero Kristo wrote: > Certain watchdogs require the watchdog only to be pinged within a > specific time window, pinging too early or too late cause the watchdog > to fire. In cases where this sort of watchdog has been started before > kernel comes up, we must adjust the watchdog keepalive window to match > the actually running timer, so add a new driver API for this purpose. > > Signed-off-by: Tero Kristo <[email protected]>
Reviewed-by: Guenter Roeck <[email protected]> > --- > .../watchdog/watchdog-kernel-api.rst | 12 ++++++++ > drivers/watchdog/watchdog_dev.c | 30 +++++++++++++++++++ > include/linux/watchdog.h | 2 ++ > 3 files changed, 44 insertions(+) > > diff --git a/Documentation/watchdog/watchdog-kernel-api.rst > b/Documentation/watchdog/watchdog-kernel-api.rst > index 068a55ee0d4a..baf44e986b07 100644 > --- a/Documentation/watchdog/watchdog-kernel-api.rst > +++ b/Documentation/watchdog/watchdog-kernel-api.rst > @@ -336,3 +336,15 @@ an action is taken by a preconfigured pretimeout > governor preassigned to > the watchdog device. If watchdog pretimeout governor framework is not > enabled, watchdog_notify_pretimeout() prints a notification message to > the kernel log buffer. > + > +To set the last known HW keepalive time for a watchdog, the following > function > +should be used:: > + > + int watchdog_set_last_hw_keepalive(struct watchdog_device *wdd, > + unsigned int last_ping_ms) > + > +This function must be called immediately after watchdog registration. It > +sets the last known hardware heartbeat to have happened last_ping_ms before > +current time. Calling this is only needed if the watchdog is already running > +when probe is called, and the watchdog can only be pinged after the > +min_hw_heartbeat_ms time has passed from the last ping. > diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c > index bc1cfa288553..e74a0c6811b5 100644 > --- a/drivers/watchdog/watchdog_dev.c > +++ b/drivers/watchdog/watchdog_dev.c > @@ -1138,6 +1138,36 @@ void watchdog_dev_unregister(struct watchdog_device > *wdd) > watchdog_cdev_unregister(wdd); > } > > +/* > + * watchdog_set_last_hw_keepalive: set last HW keepalive time for watchdog > + * @wdd: watchdog device > + * @last_ping_ms: time since last HW heartbeat > + * > + * Adjusts the last known HW keepalive time for a watchdog timer. > + * This is needed if the watchdog is already running when the probe > + * function is called, and it can't be pinged immediately. This > + * function must be called immediately after watchdog registration, > + * and min_hw_heartbeat_ms must be set for this to be useful. > + */ > +int watchdog_set_last_hw_keepalive(struct watchdog_device *wdd, > + unsigned int last_ping_ms) > +{ > + struct watchdog_core_data *wd_data; > + ktime_t now; > + > + if (!wdd) > + return -EINVAL; > + > + wd_data = wdd->wd_data; > + > + now = ktime_get(); > + > + wd_data->last_hw_keepalive = ktime_sub(now, ms_to_ktime(last_ping_ms)); > + > + return __watchdog_ping(wdd); > +} > +EXPORT_SYMBOL_GPL(watchdog_set_last_hw_keepalive); > + > /* > * watchdog_dev_init: init dev part of watchdog core > * > diff --git a/include/linux/watchdog.h b/include/linux/watchdog.h > index 1464ce6ffa31..9b19e6bb68b5 100644 > --- a/include/linux/watchdog.h > +++ b/include/linux/watchdog.h > @@ -210,6 +210,8 @@ extern int watchdog_init_timeout(struct watchdog_device > *wdd, > extern int watchdog_register_device(struct watchdog_device *); > extern void watchdog_unregister_device(struct watchdog_device *); > > +int watchdog_set_last_hw_keepalive(struct watchdog_device *, unsigned int); > + > /* devres register variant */ > int devm_watchdog_register_device(struct device *dev, struct watchdog_device > *); > >
