watchdog: add watchdog poller ...

In some cases it is practical to supervise as much as possible of
the barebox execution with a watchdog (or multiple watchdogs). This
patch provides an async poller for watchdog core framework which can
be enabled by the user and stores this configuration to nv.

Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

watchdog: provide timeout_cur value ...

timeout_cur will be used for watchdog poller.
Provided values should be good enough for most users
and still can be changed for separate projects and
fit to needed requirements.

Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

watchdog: set some reasonable timeout_max value if no other is available ...

Some drivers do not provide timeout_max value.
Using some value is probably better then setting timeout_max to 0.

Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

watchdog: move max timeout test in to wd_core ...

this also will be needed for watchdog poller as well

Signed-off-by: Oleksij Rempel <linux@rempel-privat.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

watchdog: register watchdog virtual device with short name wdog ...

the watchdog hwdev is usually named with devicetree schema
which is not practical for CLI.

On device registration "wdog" will be extended with some index number
extracted from devicetree (if awailable) or automatically assigned
first available number. End result will be "wdog0" .. etc.

Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

watchdog: rename dev to hwdev ...

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

watchdog: Give watchdogs a name ...

This adds a dev and name member to struct watchdog which helps distinguishing
between different watchdogs. Also add some debugging aids.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

watchdog: Allow multiple watchdogs ...

Put watchdogs on a list to allow multiple watchdogs. Add a priority
field to be able to pick the highest priority watchdog.
This patch also provides a of_get_watchdog_priority() function to
allow configuring the watchdog priority from the device tree.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

Add a simple watchdog framework ...

This patch adds a simple wd command which can setup, trigger and stop a watchdog
on the platform.

Signed-off-by: Juergen Beisert <jbe@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>