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Convert those documents and prepare them to be part of the kernel
API book, as most of the stuff there are related to the
Kernel interfaces.
Still, in the future, it would make sense to split the docs,
as some of the stuff is clearly focused on sysadmin tasks.
The conversion is actually:
- add blank lines and identation in order to identify paragraphs;
- fix tables markups;
- add some lists markups;
- mark literal blocks;
- adjust title markups.
At its new index.rst, let's add a :orphan: while this is not linked to
the main index.rst file, in order to avoid build warnings.
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
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Those functions are not only deprecated, but gone for good.
Fixes: 62cd1c40ce1c ("watchdog: kill unref/ref ops")
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.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@linux-watchdog.org>
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Many watchdog drivers explicitly stop the watchdog when unregistering it.
While it is unclear if this is actually needed (the whatdog should not be
running at that time if it can be stopped), introduce a helper to
explicitly stop the watchdog in the watchdog core when unregistering it.
This helps reducing driver code size while retaining functionality.
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
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The change adds a simple watchdog pretimeout framework infrastructure,
its purpose is to allow users to select a desired handling of watchdog
pretimeout events, which may be generated by some watchdog devices.
A user selects a default watchdog pretimeout governor during
compilation stage.
Watchdogs with WDIOF_PRETIMEOUT capability now have one more device
attribute in sysfs, pretimeout_governor attribute is intended to display
the selected watchdog pretimeout governor.
The framework has no impact at runtime on watchdog devices with no
WDIOF_PRETIMEOUT capability set.
Signed-off-by: Vladimir Zapolskiy <vladimir_zapolskiy@mentor.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Tested-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
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Since the watchdog framework centrializes the IOCTL interfaces of device
drivers now, SETPRETIMEOUT and GETPRETIMEOUT need to be added in the
common code.
Signed-off-by: Robin Gong <b38343@freescale.com>
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
[vzapolskiy: added conditional pretimeout sysfs attribute visibility]
Signed-off-by: Vladimir Zapolskiy <vladimir_zapolskiy@mentor.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>
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Up to now, the watchdog status function called a driver function,
which was supposed to return the watchdog status. All but one
driver using the watchdog core did not implement this function,
and the driver implementing it did not implement it correctly
(the function is supposed to return WDIOF_ flags). At the same time,
at least some of the status information can be provided by the watchdog
core.
Provide the available status bits directly from the watchdog driver core.
Call the driver status function if it exists to get the boot status, but
always provide WDIOF_MAGICCLOSE and WDIOF_KEEPALIVEPING internally.
This patch makes the 'status' sysfs attribute always available.
This attribute is now displayed as hex number with 0x prepended to be
easier to decode.
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
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The description of min_hw_heartbeat_ms is misleading and needs some
improvements.
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
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Some watchdogs require a minimum time between heartbeats.
Examples are the watchdogs in DA9062 and AT91SAM9x.
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
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Not all hardware watchdogs can be stopped. The driver for
such watchdogs would typically only set the WATCHDOG_HW_RUNNING
flag in its stop function. Make the stop function optional and set
WATCHDOG_HW_RUNNING in the watchdog core if it is not provided.
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
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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 <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
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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 <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
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For some watchdogs, the watchdog driver handles timeout changes without
explicitly setting any registers. In this situation, the watchdog driver
might only set the 'timeout' variable but do nothing else.
This can as well be handled by the infrastructure, so make the set_timeout
callback optional. If WDIOF_SETTIMEOUT is configured but the .set_timeout
callback is not available, update the timeout variable in the
infrastructure code.
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
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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>
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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 <linux@roeck-us.net>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
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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>
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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>
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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>
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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>
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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>
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If a driver's watchdog_device struct is part of a dynamically allocated
struct (which it often will be), merely locking the module is not enough,
even with a drivers module locked, the driver can be unbound from the device,
examples:
1) The root user can unbind it through sysfd
2) The i2c bus master driver being unloaded for an i2c watchdog
I will gladly admit that these are corner cases, but we still need to handle
them correctly.
The fix for this consists of 2 parts:
1) Add ref / unref operations, so that the driver can refcount the struct
holding the watchdog_device struct and delay freeing it until any
open filehandles referring to it are closed
2) Most driver operations will do IO on the device and the driver should not
do any IO on the device after it has been unbound. Rather then letting each
driver deal with this internally, it is better to ensure at the watchdog
core level that no operations (other then unref) will get called after
the driver has called watchdog_unregister_device(). This actually is the
bulk of this patch.
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
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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>
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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>
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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>
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Signed-off-by: Devendra Naga <devendra.aaru@gmail.com>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
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This patch adds support for WDIOC_GETTIMELEFT IOCTL in watchdog core. So, there
is another function pointer added to struct watchdog_ops, which can be passed by
drivers to support this IOCTL.
Related documentation is updated too.
Signed-off-by: Viresh Kumar <viresh.kumar@st.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
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When a set_timeout operation succeeds this does not necessarily mean that
the exact timeout requested has been achieved, because the watchdog does not
necessarily have a 1 second resolution. So rather then have the core set
the timeout member of the watchdog_device struct to the exact requested
value, instead the driver should set it to the actually achieved timeout value.
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
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Correct spelling "retruns" to "returns" in
Documentations/watchdog/watchdog-kernel-api.txt
Signed-off-by: Masanari Iida <standby24x7@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
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Add two nowayout helpers for the Watchdog Timer Driver Kernel API.
And apply this to the already converted drivers.
Note: s3c2410_wdt lost the nowayout feature during the conversion.
Reviewed-by: Wolfram Sang <w.sang@pengutronix.de>
Acked-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
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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>
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Add support for extra ioctl calls by adding a
ioctl watchdog operation. This operation will be
called before we do our own handling of ioctl
commands. This way we can override the internal
ioctl command handling and we can also add
extra ioctl commands. The ioctl watchdog operation
should return the appropriate error codes or
-ENOIOCTLCMD if the ioctl command should be handled
through the internal ioctl handling of the framework.
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>
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Add support for the nowayout feature to the
WatchDog Timer Driver Core framework.
This feature prevents the watchdog timer from being
stopped.
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>
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Add support for the Magic Close feature to the
WatchDog Timer Driver Core framework.
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>
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This part add's the WDIOC_SETTIMEOUT and WDIOC_GETTIMEOUT ioctl
functionality to the WatchDog Timer Driver Core framework.
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>
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This part add's the WDIOC_SETOPTIONS ioctl functionality
to the WatchDog Timer Driver Core framework.
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>
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This part add's the WDIOC_KEEPALIVE ioctl functionality to the
WatchDog Timer Driver Core framework. Please note that the
WDIOF_KEEPALIVEPING bit has to be set in the watchdog_info
options field.
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>
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This part add's the basic ioctl functionality to the
WatchDog Timer Driver Core framework. The supported
ioctl call's are:
WDIOC_GETSUPPORT
WDIOC_GETSTATUS
WDIOC_GETBOOTSTATUS
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>
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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>
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Mauro Carvalho Chehab
Wolfram Sang
Guenter Roeck
Vladimir Zapolskiy
Damien Riegel
Jean-Baptiste Theou
Fabio Porcedda
Hans de Goede
Alan Cox
Devendra Naga
Viresh Kumar
Masanari Iida
Wim Van Sebroeck