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Alan Cox authored and Wim Van Sebroeck committed May 24, 2007
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2 changes: 1 addition & 1 deletion [refs]
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---
refs/heads/master: ccb8f430ac4cfd1acd12ff591918b8b67d73c977
refs/heads/master: 4d389dcea8543161c3bb1e26f1c2ffb7e0822ff1
8 changes: 4 additions & 4 deletions trunk/Documentation/watchdog/pcwd-watchdog.txt
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Last reviewed: 10/05/2007

Berkshire Products PC Watchdog Card
Support for ISA Cards Revision A and C
Documentation and Driver by Ken Hollis <kenji@bitgate.com>
Expand All @@ -14,8 +16,8 @@

The Watchdog Driver will automatically find your watchdog card, and will
attach a running driver for use with that card. After the watchdog
drivers have initialized, you can then talk to the card using the PC
Watchdog program, available from http://ftp.bitgate.com/pcwd/.
drivers have initialized, you can then talk to the card using a PC
Watchdog program.

I suggest putting a "watchdog -d" before the beginning of an fsck, and
a "watchdog -e -t 1" immediately after the end of an fsck. (Remember
Expand Down Expand Up @@ -62,5 +64,3 @@
-- Ken Hollis
(kenji@bitgate.com)

(This documentation may be out of date. Check
http://ftp.bitgate.com/pcwd/ for the absolute latest additions.)
236 changes: 13 additions & 223 deletions trunk/Documentation/watchdog/watchdog-api.txt
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Last reviewed: 10/05/2007


The Linux Watchdog driver API.

Copyright 2002 Christer Weingel <wingel@nano-system.com>
Expand All @@ -22,7 +25,7 @@ the system. If userspace fails (RAM error, kernel bug, whatever), the
notifications cease to occur, and the hardware watchdog will reset the
system (causing a reboot) after the timeout occurs.

The Linux watchdog API is a rather AD hoc construction and different
The Linux watchdog API is a rather ad-hoc construction and different
drivers implement different, and sometimes incompatible, parts of it.
This file is an attempt to document the existing usage and allow
future driver writers to use it as a reference.
Expand All @@ -46,14 +49,16 @@ some of the drivers support the configuration option "Disable watchdog
shutdown on close", CONFIG_WATCHDOG_NOWAYOUT. If it is set to Y when
compiling the kernel, there is no way of disabling the watchdog once
it has been started. So, if the watchdog daemon crashes, the system
will reboot after the timeout has passed.
will reboot after the timeout has passed. Watchdog devices also usually
support the nowayout module parameter so that this option can be controlled
at runtime.

Some other drivers will not disable the watchdog, unless a specific
magic character 'V' has been sent /dev/watchdog just before closing
the file. If the userspace daemon closes the file without sending
this special character, the driver will assume that the daemon (and
userspace in general) died, and will stop pinging the watchdog without
disabling it first. This will then cause a reboot.
Drivers will not disable the watchdog, unless a specific magic character 'V'
has been sent /dev/watchdog just before closing the file. If the userspace
daemon closes the file without sending this special character, the driver
will assume that the daemon (and userspace in general) died, and will stop
pinging the watchdog without disabling it first. This will then cause a
reboot if the watchdog is not re-opened in sufficient time.

The ioctl API:

Expand Down Expand Up @@ -227,218 +232,3 @@ The following options are available:

[FIXME -- better explanations]

Implementations in the current drivers in the kernel tree:

Here I have tried to summarize what the different drivers support and
where they do strange things compared to the other drivers.

acquirewdt.c -- Acquire Single Board Computer

This driver has a hardcoded timeout of 1 minute

Supports CONFIG_WATCHDOG_NOWAYOUT

GETSUPPORT returns KEEPALIVEPING. GETSTATUS will return 1 if
the device is open, 0 if not. [FIXME -- isn't this rather
silly? To be able to use the ioctl, the device must be open
and so GETSTATUS will always return 1].

advantechwdt.c -- Advantech Single Board Computer

Timeout that defaults to 60 seconds, supports SETTIMEOUT.

Supports CONFIG_WATCHDOG_NOWAYOUT

GETSUPPORT returns WDIOF_KEEPALIVEPING and WDIOF_SETTIMEOUT.
The GETSTATUS call returns if the device is open or not.
[FIXME -- silliness again?]

booke_wdt.c -- PowerPC BookE Watchdog Timer

Timeout default varies according to frequency, supports
SETTIMEOUT

Watchdog cannot be turned off, CONFIG_WATCHDOG_NOWAYOUT
does not make sense

GETSUPPORT returns the watchdog_info struct, and
GETSTATUS returns the supported options. GETBOOTSTATUS
returns a 1 if the last reset was caused by the
watchdog and a 0 otherwise. This watchdog cannot be
disabled once it has been started. The wdt_period kernel
parameter selects which bit of the time base changing
from 0->1 will trigger the watchdog exception. Changing
the timeout from the ioctl calls will change the
wdt_period as defined above. Finally if you would like to
replace the default Watchdog Handler you can implement the
WatchdogHandler() function in your own code.

eurotechwdt.c -- Eurotech CPU-1220/1410

The timeout can be set using the SETTIMEOUT ioctl and defaults
to 60 seconds.

Also has a module parameter "ev", event type which controls
what should happen on a timeout, the string "int" or anything
else that causes a reboot. [FIXME -- better description]

Supports CONFIG_WATCHDOG_NOWAYOUT

GETSUPPORT returns CARDRESET and WDIOF_SETTIMEOUT but
GETSTATUS is not supported and GETBOOTSTATUS just returns 0.

i810-tco.c -- Intel 810 chipset

Also has support for a lot of other i8x0 stuff, but the
watchdog is one of the things.

The timeout is set using the module parameter "i810_margin",
which is in steps of 0.6 seconds where 2<i810_margin<64. The
driver supports the SETTIMEOUT ioctl.

Supports CONFIG_WATCHDOG_NOWAYOUT.

GETSUPPORT returns WDIOF_SETTIMEOUT. The GETSTATUS call
returns some kind of timer value which ist not compatible with
the other drivers. GETBOOT status returns some kind of
hardware specific boot status. [FIXME -- describe this]

ib700wdt.c -- IB700 Single Board Computer

Default timeout of 30 seconds and the timeout is settable
using the SETTIMEOUT ioctl. Note that only a few timeout
values are supported.

Supports CONFIG_WATCHDOG_NOWAYOUT

GETSUPPORT returns WDIOF_KEEPALIVEPING and WDIOF_SETTIMEOUT.
The GETSTATUS call returns if the device is open or not.
[FIXME -- silliness again?]

machzwd.c -- MachZ ZF-Logic

Hardcoded timeout of 10 seconds

Has a module parameter "action" that controls what happens
when the timeout runs out which can be 0 = RESET (default),
1 = SMI, 2 = NMI, 3 = SCI.

Supports CONFIG_WATCHDOG_NOWAYOUT and the magic character
'V' close handling.

GETSUPPORT returns WDIOF_KEEPALIVEPING, and the GETSTATUS call
returns if the device is open or not. [FIXME -- silliness
again?]

mixcomwd.c -- MixCom Watchdog

[FIXME -- I'm unable to tell what the timeout is]

Supports CONFIG_WATCHDOG_NOWAYOUT

GETSUPPORT returns WDIOF_KEEPALIVEPING, GETSTATUS returns if
the device is opened or not [FIXME -- I'm not really sure how
this works, there seems to be some magic connected to
CONFIG_WATCHDOG_NOWAYOUT]

pcwd.c -- Berkshire PC Watchdog

Hardcoded timeout of 1.5 seconds

Supports CONFIG_WATCHDOG_NOWAYOUT

GETSUPPORT returns WDIOF_OVERHEAT|WDIOF_CARDRESET and both
GETSTATUS and GETBOOTSTATUS return something useful.

The SETOPTIONS call can be used to enable and disable the card
and to ask the driver to call panic if the system overheats.

sbc60xxwdt.c -- 60xx Single Board Computer

Hardcoded timeout of 10 seconds

Does not support CONFIG_WATCHDOG_NOWAYOUT, but has the magic
character 'V' close handling.

No bits set in GETSUPPORT

scx200.c -- National SCx200 CPUs

Not in the kernel yet.

The timeout is set using a module parameter "margin" which
defaults to 60 seconds. The timeout can also be set using
SETTIMEOUT and read using GETTIMEOUT.

Supports a module parameter "nowayout" that is initialized
with the value of CONFIG_WATCHDOG_NOWAYOUT. Also supports the
magic character 'V' handling.

shwdt.c -- SuperH 3/4 processors

[FIXME -- I'm unable to tell what the timeout is]

Supports CONFIG_WATCHDOG_NOWAYOUT

GETSUPPORT returns WDIOF_KEEPALIVEPING, and the GETSTATUS call
returns if the device is open or not. [FIXME -- silliness
again?]

softdog.c -- Software watchdog

The timeout is set with the module parameter "soft_margin"
which defaults to 60 seconds, the timeout is also settable
using the SETTIMEOUT ioctl.

Supports CONFIG_WATCHDOG_NOWAYOUT

WDIOF_SETTIMEOUT bit set in GETSUPPORT

w83877f_wdt.c -- W83877F Computer

Hardcoded timeout of 30 seconds

Does not support CONFIG_WATCHDOG_NOWAYOUT, but has the magic
character 'V' close handling.

No bits set in GETSUPPORT

w83627hf_wdt.c -- w83627hf watchdog

Timeout that defaults to 60 seconds, supports SETTIMEOUT.

Supports CONFIG_WATCHDOG_NOWAYOUT

GETSUPPORT returns WDIOF_KEEPALIVEPING and WDIOF_SETTIMEOUT.
The GETSTATUS call returns if the device is open or not.

wdt.c -- ICS WDT500/501 ISA and
wdt_pci.c -- ICS WDT500/501 PCI

Default timeout of 60 seconds. The timeout is also settable
using the SETTIMEOUT ioctl.

Supports CONFIG_WATCHDOG_NOWAYOUT

GETSUPPORT returns with bits set depending on the actual
card. The WDT501 supports a lot of external monitoring, the
WDT500 much less.

wdt285.c -- Footbridge watchdog

The timeout is set with the module parameter "soft_margin"
which defaults to 60 seconds. The timeout is also settable
using the SETTIMEOUT ioctl.

Does not support CONFIG_WATCHDOG_NOWAYOUT

WDIOF_SETTIMEOUT bit set in GETSUPPORT

wdt977.c -- Netwinder W83977AF chip

Hardcoded timeout of 3 minutes

Supports CONFIG_WATCHDOG_NOWAYOUT

Does not support any ioctls at all.

94 changes: 0 additions & 94 deletions trunk/Documentation/watchdog/watchdog.txt
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