Commit Graph

20 Commits

Author SHA1 Message Date
Guenter Roeck
0254e95353 watchdog: Drop pointer to watchdog device from struct watchdog_device
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 <linux@roeck-us.net>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
2016-01-11 21:53:59 +01:00
Guenter Roeck
b4ffb19098 watchdog: Separate and maintain variables based on variable lifetime
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 <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
2015-12-29 20:36:03 +01:00
Guenter Roeck
32ecc63926 watchdog: Create watchdog device in watchdog_dev.c
The watchdog character device is currently created in watchdog_dev.c,
and the watchdog device in watchdog_core.c. This results in
cross-dependencies, since device creation needs to know the watchdog
character device number as well as the watchdog class, both of which
reside in watchdog_dev.c.

Create the watchdog device in watchdog_dev.c to simplify the code.

Inspired by earlier patch set from Damien Riegel.

Cc: Damien Riegel <damien.riegel@savoirfairelinux.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
2015-12-29 20:36:01 +01:00
Pratyush Anand
33b711269a watchdog: Read device status through sysfs attributes
This patch adds following attributes to watchdog device's sysfs interface
to read its different status.

* state - reads whether device is active or not
* identity - reads Watchdog device's identity string.
* timeout - reads current timeout.
* timeleft - reads timeleft before watchdog generates a reset
* bootstatus - reads status of the watchdog device at boot
* status - reads watchdog device's  internal status bits
* nowayout - reads whether nowayout feature was set or not

Testing with iTCO_wdt:
 # cd /sys/class/watchdog/watchdog1/
 # ls
bootstatus  dev  device  identity  nowayout  power  state
subsystem  timeleft  timeout  uevent
 # cat identity
iTCO_wdt
 # cat timeout
30
 # cat state
inactive
 # echo > /dev/watchdog1
 # cat timeleft
26
 # cat state
active
 # cat bootstatus
0
 # cat nowayout
0

Signed-off-by: Pratyush Anand <panand@redhat.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
2015-12-27 16:55:57 +01:00
Pratyush Anand
906d7a5cfe watchdog: Use static struct class watchdog_class in stead of pointer
We need few sysfs attributes to know different status of a watchdog device.
To do that, we need to associate .dev_groups with watchdog_class. So
convert it from pointer to static.
Putting this static struct in watchdog_dev.c, so that static device
attributes defined in that file can be attached to it.

Signed-off-by: Pratyush Anand <panand@redhat.com>
Suggested-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
2015-12-27 16:54:54 +01:00
Damien Riegel
e131319669 watchdog: core: add reboot notifier support
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 <vivien.didelot@savoirfairelinux.com>
Signed-off-by: Damien Riegel <damien.riegel@savoirfairelinux.com>
Reviewed-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
2015-12-13 15:55:51 +01:00
Damien Riegel
2165bf524d watchdog: core: add restart handler support
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 <vivien.didelot@savoirfairelinux.com>
Signed-off-by: Damien Riegel <damien.riegel@savoirfairelinux.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
2015-12-13 15:27:10 +01:00
Justin Chen
9dd4e173f7 watchdog: watchdog_dev: Use device tree alias for naming watchdogs
Currently there is no way to easily differentiate multiple
watchdog devices. The watchdogs are named by the order they
are probed.
1st probed watchdog: /dev/watchdog0
2nd probed watchdog: /dev/watchdog1
...

This change uses the alias of the watchdog device node for
the name of the watchdog.
aliases {
    watchdog0 = "/...../...."
    watchdog3 = "/..../....."
    watchdog2 = "/..../....."
    ...
}

This will translate to...
/dev/watchdog0
/dev/watchdog3
/dev/watchdog2

v2
Assign alias number to id in watchdog_core instead of watchdog_dev.
If failed to get id, fallback to original ida_simple_get call.

Signed-off-by: Justin Chen <justinpopo6@gmail.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
2015-10-27 16:49:57 +01:00
Jean-Baptiste Theou
ef90174f82 watchdog: watchdog_core: Add watchdog registration deferral mechanism
Currently, watchdog subsystem require the misc subsystem to
register a watchdog. This may not be the case in case of an
early registration of a watchdog, which can be required when
the watchdog cannot be disabled.

This patch introduces a deferral mechanism to remove this requirement.

Signed-off-by: Jean-Baptiste Theou <jtheou@adeneo-embedded.us>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
2015-06-29 11:51:06 +02:00
Doug Anderson
2c34d59916 watchdog: core: Make dt "timeout-sec" property work on drivers w/out min/max
It is valid for a watchdog driver to have 0 for a "min" and "max"
timeout if the driver doesn't need the core to enforce the concepts of
min and max.  The s3c2410_wdt driver is one such driver.  Specifically
it can be hard for that driver to come up with a static "max" on all
platforms without a lot more information since the input clock on
S3C2410 and S3C2440 can change with DVFS.

As written, watchdog_init_timeout() will not ever read "timeout-sec"
on these drivers since watchdog_timeout_invalid() will _never_ return
true.  Change to not consider a timeout_parm of 0 as valid even if
min/max aren't specified by the driver.  Also handle the case when
there is no min/max and no "timeout-sec" property.

Signed-off-by: Doug Anderson <dianders@chromium.org>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
2014-01-28 19:07:56 +01:00
Sachin Kamat
6ffcff9319 watchdog: watchdog_core: Fix a trivial typo
Fixed a trivial typo.

Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
2013-11-17 19:38:34 +01:00
Fabio Porcedda
3048253ed9 watchdog: core: dt: add support for the timeout-sec dt property
Add support for watchdog drivers to initialize/set the timeout field
of the watchdog_device structure. The timeout field is initialised
either with the module timeout parameter value (if valid) or with the
timeout-sec dt property (if valid). If both are invalid the initial
value is unchanged.

Signed-off-by: Fabio Porcedda <fabio.porcedda@gmail.com>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
2013-03-01 12:48:36 +01:00
Wei Yongjun
b232a70a17 watchdog: move the dereference below the NULL test
The dereference should be moved below the NULL test.

spatch with a semantic match is used to found this.
(http://coccinelle.lip6.fr/)

Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
2012-09-10 17:33:17 +02:00
Hans de Goede
f4e9c82f64 watchdog: Add Locking support
This patch fixes some potential multithreading issues, despite only
allowing one process to open the /dev/watchdog device, we can still get
called multiple times at the same time, since a program could be using thread,
or could share the fd after a fork.

This causes 2 potential problems:
1) watchdog_start / open do an unlocked test_n_set / test_n_clear,
   if these 2 race, the watchdog could be stopped while the active
   bit indicates it is running or visa versa.

2) Most watchdog_dev drivers probably assume that only one
   watchdog-op will get called at a time, this is not necessary
   true atm.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
2012-05-30 07:55:23 +02:00
Alan Cox
d6b469d915 watchdog: create all the proper device files
Create the watchdog class and it's associated devices.

Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
2012-05-30 07:54:46 +02:00
Alan Cox
45f5fed30a watchdog: Add multiple device support
We keep the old /dev/watchdog interface file for the first watchdog via
miscdev. This is basically a cut and paste of the relevant interface code
from the rtc driver layer tweaked for watchdog.

Revised to fix problems noted by Hans de Goede

Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
2012-05-30 07:54:25 +02:00
Wim Van Sebroeck
6cfb5aa836 watchdog: correct the name of the watchdog_core inlude file
The watchdog_core include file should have been named
watchdog_core.h and not watchdog_dev.h . Correct this.

Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
2012-05-30 07:54:03 +02:00
Joe Perches
27c766aaac watchdog: Use pr_<fmt> and pr_<level>
Use the current logging styles.

Make sure all output has a prefix.
Add missing newlines.
Remove now unnecessary PFX, NAME, and miscellaneous other #defines.
Coalesce formats.

Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
2012-03-27 19:59:26 +02:00
Wim Van Sebroeck
3f43f68e29 watchdog: WatchDog Timer Driver Core - Add minimum and max timeout
Add min_timeout (minimum timeout) and max_timeout
values so that the framework can check if the new
timeout value is between the minimum and maximum
timeout values. If both values are 0, then the
framework will leave the check for the watchdog
device driver itself.

Signed-off-by: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Wolfram Sang <w.sang@pengutronix.de>
2011-07-28 08:01:18 +00:00
Wim Van Sebroeck
43316044d4 watchdog: WatchDog Timer Driver Core - Add basic framework
The WatchDog Timer Driver Core is a framework
that contains the common code for all watchdog-driver's.
It also introduces a watchdog device structure and the
operations that go with it.

This is the introduction of this framework. This part
supports the minimal watchdog userspace API (or with
other words: the functionality to use /dev/watchdog's
open, release and write functionality as defined in
the simplest watchdog API). Extra functionality will
follow in the next set of patches.

Signed-off-by: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Wolfram Sang <w.sang@pengutronix.de>
2011-07-28 08:01:04 +00:00