linux-toradex.git/include/linux/watchdog.h, branch v4.6-rc3

watchdog: Add support for minimum time between heartbeats

2016-03-16T20:11:19+00:00

Some watchdogs require a minimum time between heartbeats.
Examples are the watchdogs in DA9062 and AT91SAM9x.

Signed-off-by: Guenter Roeck 
Signed-off-by: Wim Van Sebroeck

watchdog: Introduce WDOG_HW_RUNNING flag

2016-03-16T20:11:15+00:00

The WDOG_HW_RUNNING flag is expected to be set by watchdog drivers if
the hardware watchdog is running. If the flag is set, the watchdog
subsystem will ping the watchdog even if the watchdog device is closed.

The watchdog driver stop function is now optional and may be omitted
if the watchdog can not be stopped. If stopping the watchdog is not
possible but the driver implements a stop function, it is responsible
to set the WDOG_HW_RUNNING flag in its stop function.

Signed-off-by: Guenter Roeck 
Signed-off-by: Wim Van Sebroeck

watchdog: Introduce hardware maximum heartbeat in watchdog core

2016-03-16T20:11:14+00:00

Introduce an optional hardware maximum heartbeat in the watchdog core.
The hardware maximum heartbeat can be lower than the maximum timeout.

Drivers can set the maximum hardware heartbeat value in the watchdog data
structure. If the configured timeout exceeds the maximum hardware heartbeat,
the watchdog core enables a timer function to assist sending keepalive
requests to the watchdog driver.

Signed-off-by: Guenter Roeck 
Signed-off-by: Wim Van Sebroeck

watchdog: Add 'action' and 'data' parameters to restart handler callback

2016-03-01T14:36:35+00:00

The 'action' (or restart mode) and data parameters may be used by restart
handlers, so they should be passed to the restart callback functions.

Cc: Sylvain Lemieux 
Signed-off-by: Guenter Roeck 
Signed-off-by: Wim Van Sebroeck

watchdog: Drop pointer to watchdog device from struct watchdog_device

2016-01-11T20:53:59+00:00

The lifetime of the watchdog device pointer is different from the lifetime
of its character device. Remove it entirely to avoid race conditions.

Signed-off-by: Guenter Roeck 
Signed-off-by: Guenter Roeck 
Signed-off-by: Wim Van Sebroeck

watchdog: Add support for creating driver specific sysfs attributes

2016-01-11T20:53:57+00:00

The Zodiac watchdog driver attaches additional sysfs attributes to the
watchdog device. This has a number of problems: The watchdog device
lifetime differs from the driver lifetime, and the device structure
should therefore not be accessed from drivers. Also, creating sysfs
attributes after driver registration results in a potential race condition
if user space expects the attributes to exist but they don't exist yet.

Add support for creating driver specific sysfs attributes to the watchdog
core to solve the problems.

Signed-off-by: Guenter Roeck 
Signed-off-by: Guenter Roeck 
Signed-off-by: Wim Van Sebroeck

watchdog: kill unref/ref ops

2016-01-11T20:52:51+00:00

ref/unref ops are not called at all so even marked them as deprecated
is misleading, we need to just drop the API.

Signed-off-by: Tomas Winkler 
Signed-off-by: Guenter Roeck 
Signed-off-by: Wim Van Sebroeck

watchdog: Separate and maintain variables based on variable lifetime

2015-12-29T19:36:03+00:00

All variables required by the watchdog core to manage a watchdog are
currently stored in struct watchdog_device. The lifetime of those
variables is determined by the watchdog driver. However, the lifetime
of variables used by the watchdog core differs from the lifetime of
struct watchdog_device. To remedy this situation, watchdog drivers
can implement ref and unref callbacks, to be used by the watchdog
core to lock struct watchdog_device in memory.

While this solves the immediate problem, it depends on watchdog drivers
to actually implement the ref/unref callbacks. This is error prone,
often not implemented in the first place, or not implemented correctly.

To solve the problem without requiring driver support, split the variables
in struct watchdog_device into two data structures - one for variables
associated with the watchdog driver, one for variables associated with
the watchdog core. With this approach, the watchdog core can keep track
of its variable lifetime and no longer depends on ref/unref callbacks
in the driver. As a side effect, some of the variables originally in
struct watchdog_driver are now private to the watchdog core and no longer
visible in watchdog drivers.

As a side effect of the changes made, an ioctl will now always fail
with -ENODEV after a watchdog device was unregistered with the character
device still open. Previously, it would only fail with -ENODEV in some
situations. Also, ioctl operations are now atomic from driver perspective.
With this change, it is now guaranteed that the driver will not unregister
a watchdog between a timeout change and the subsequent ping.

The 'ref' and 'unref' callbacks in struct watchdog_driver are no longer
used and marked as deprecated.

Signed-off-by: Guenter Roeck 
Signed-off-by: Wim Van Sebroeck

watchdog: core: add reboot notifier support

2015-12-13T14:55:51+00:00

Many watchdog drivers register a reboot notifier in order to stop the
watchdog on system reboot. Thus we can factorize this code in the
watchdog core.

For that purpose, a new notifier block is added in watchdog_device for
internal use only, as well as a new watchdog_stop_on_reboot helper
function.

If this helper is called, watchdog core registers the related notifier
block and will stop the watchdog when SYS_HALT or SYS_DOWN is received.

Since this operation can be critical on some platforms, abort the device
registration if the reboot notifier registration fails.

Suggested-by: Vivien Didelot 
Signed-off-by: Damien Riegel 
Reviewed-by: Vivien Didelot 
Signed-off-by: Guenter Roeck 
Signed-off-by: Wim Van Sebroeck

watchdog: core: add restart handler support

2015-12-13T14:27:10+00:00

Many watchdog drivers implement the same code to register a restart
handler. This patch provides a generic way to set such a function.

The patch adds a new restart watchdog operation. If a restart priority
greater than 0 is needed, the driver can call
watchdog_set_restart_priority to set it.

Suggested-by: Vivien Didelot 
Signed-off-by: Damien Riegel 
Reviewed-by: Guenter Roeck 
Reviewed-by: Vivien Didelot 
Signed-off-by: Guenter Roeck 
Signed-off-by: Wim Van Sebroeck