linux.git/Documentation/watchdog, branch v5.3.2

Merge branch 'pdf_fixes_v1' of https://git.linuxtv.org/mchehab/experimental into mauro

2019-07-22T19:51:20+00:00

Bring in a set of post-thrashup fixes from Mauro.

Merge tag 'linux-watchdog-5.3-rc1' of git://www.linux-watchdog.org/linux-watchdog

2019-07-18T17:47:59+00:00

Pull watchdog updates from Wim Van Sebroeck:

 - add Allwinner H6 watchdog

 - drop warning after registering device patches

 - hpwdt improvements

 - gpio: add support for nowayout option

 - introduce CONFIG_WATCHDOG_OPEN_TIMEOUT

 - convert remaining drivers to use SPDX license identifier

 - Fixes and improvements on several watchdog device drivers

* tag 'linux-watchdog-5.3-rc1' of git://www.linux-watchdog.org/linux-watchdog: (74 commits)
  watchdog: digicolor_wdt: Remove unused variable in dc_wdt_probe
  watchdog: ie6xx_wdt: Use spinlock_t instead of struct spinlock
  watchdog: atmel: atmel-sama5d4-wdt: Disable watchdog on system suspend
  watchdog: convert remaining drivers to use SPDX license identifier
  dt-bindings: watchdog: Rename bindings documentation file
  watchdog: mei_wdt: no need to check return value of debugfs_create functions
  watchdog: bcm_kona_wdt: no need to check return value of debugfs_create functions
  docs: watchdog: Fix build error.
  docs: watchdog: convert docs to ReST and rename to *.rst
  watchdog: make the device time out at open_deadline when open_timeout is used
  watchdog: introduce CONFIG_WATCHDOG_OPEN_TIMEOUT
  watchdog: introduce watchdog.open_timeout commandline parameter
  dt-bindings: watchdog: move i.MX system controller watchdog binding to SCU
  watchdog: imx_sc: Add pretimeout support
  watchdog: renesas_wdt: Add a few cycles delay
  watchdog: gpio: add support for nowayout option
  watchdog: renesas_wdt: Use 'dev' instead of dereferencing it repeatedly
  dt-bindings: watchdog: add Allwinner H6 watchdog
  watchdog: jz4740: Avoid starting watchdog in set_timeout
  watchdog: jz4740: Use register names from 
  ...

docs: fix broken doc references due to renames

2019-07-17T09:57:51+00:00

Some files got renamed but probably due to some merge conflicts,
a few references still point to the old locations.

Signed-off-by: Mauro Carvalho Chehab

docs: add some directories to the main documentation index

2019-07-15T14:03:03+00:00

The contents of those directories were orphaned at the documentation
body.

While those directories could likely be moved to be inside some guide,
I'm opting to just adding their indexes to the main one, removing the
:orphan: and adding the SPDX header.

For the drivers, the rationale is that the documentation contains
a mix of Kernelspace, uAPI and admin-guide. So, better to keep them on
separate directories, as we've be doing with similar subsystem-specific
docs that were not split yet.

For the others, well... I'm too lazy to do the move. Also, it
seems to make sense to keep at least some of those at the main
dir (like kbuild, for example). In any case, a latter patch
could do the move.

Signed-off-by: Mauro Carvalho Chehab 
Acked-by: Bartlomiej Zolnierkiewicz

docs: watchdog: Fix build error.

2019-07-08T18:35:09+00:00

make htmldocs fails due to missing blank line following header.

Signed-off-by: Jerry Hoemann 
Reviewed-by: Mauro Carvalho Chehab 
Reviewed-by: Guenter Roeck 
Signed-off-by: Guenter Roeck 
Signed-off-by: Wim Van Sebroeck

docs: watchdog: convert docs to ReST and rename to *.rst

2019-07-08T18:35:09+00:00

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

watchdog: introduce CONFIG_WATCHDOG_OPEN_TIMEOUT

2019-07-08T18:04:13+00:00

This allows setting a default value for the watchdog.open_timeout
commandline parameter via Kconfig.

Some BSPs allow remote updating of the kernel image and root file
system, but updating the bootloader requires physical access. Hence, if
one has a firmware update that requires relaxing the
watchdog.open_timeout a little, the value used must be baked into the
kernel image itself and cannot come from the u-boot environment via the
kernel command line.

Being able to set the initial value in .config doesn't change the fact
that the value on the command line, if present, takes precedence, and is
of course immensely useful for development purposes while one has
console acccess, as well as usable in the cases where one can make a
permanent update of the kernel command line.

Signed-off-by: Rasmus Villemoes 
Reviewed-by: Guenter Roeck 
Signed-off-by: Guenter Roeck 
Signed-off-by: Wim Van Sebroeck

watchdog: introduce watchdog.open_timeout commandline parameter

2019-07-08T18:04:13+00:00

The watchdog framework takes care of feeding a hardware watchdog until
userspace opens /dev/watchdogN. If that never happens for some reason
(buggy init script, corrupt root filesystem or whatnot) but the kernel
itself is fine, the machine stays up indefinitely. This patch allows
setting an upper limit for how long the kernel will take care of the
watchdog, thus ensuring that the watchdog will eventually reset the
machine.

A value of 0 (the default) means infinite timeout, preserving the
current behaviour.

This is particularly useful for embedded devices where some fallback
logic is implemented in the bootloader (e.g., use a different root
partition, boot from network, ...).

There is already handle_boot_enabled serving a similar purpose. However,
such a binary choice is unsuitable if the hardware watchdog cannot be
programmed by the bootloader to provide a timeout long enough for
userspace to get up and running. Many of the embedded devices we see use
external (gpio-triggered) watchdogs with a fixed timeout of the order of
1-2 seconds.

The open timeout only applies for the first open from
userspace. Should userspace need to close the watchdog device, with
the intention of re-opening it shortly, the application can emulate
the open timeout feature by combining the nowayout feature with an
appropriate WDIOC_SETTIMEOUT immediately prior to closing the device.

Signed-off-by: Rasmus Villemoes 
Reviewed-by: Guenter Roeck 
Signed-off-by: Guenter Roeck 
Signed-off-by: Wim Van Sebroeck

watchdog/hpwdt: Update documentation

2019-07-08T14:10:09+00:00

Update documentation to explain new module parameter kdumptimeout.

Signed-off-by: Jerry Hoemann 
Reviewed-by: Guenter Roeck 
Signed-off-by: Guenter Roeck 
Signed-off-by: Wim Van Sebroeck

docs: watchdog: convert docs to ReST and rename to *.rst

2019-06-14T20:32:05+00:00

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 
Reviewed-by: Guenter Roeck 
Signed-off-by: Jonathan Corbet