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Commit 4d389dce authored May 23, 2007 by Alan Cox Committed by Wim Van Sebroeck May 24, 2007

[WATCHDOG] clean-up watchdog documentation



Random sampling of some URLs in the Documentation tree to see how many were
stale found that one watchdog driver was now a porn site.  In fact if the
watchdogs document directory was any older it would be written in latin

Clean it up somewhat and add Last reviewed headers, something all the
Documentation could do with IMHO.

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>

parent ccb8f430

Documentation/watchdog/pcwd-watchdog.txt

+4 −4

Original line number	Diff line number	Diff line
		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>
		@@ -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
		@@ -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		(This documentation may be out of date.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.)

Documentation/watchdog/watchdog-api.txt

+13 −223

Original line number	Diff line number	Diff line
		Last reviewed: 10/05/2007


		The Linux Watchdog driver API.

		Copyright 2002 Christer Weingel <wingel@nano-system.com>
		@@ -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.
		@@ -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:

		@@ -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.

Documentation/watchdog/watchdog.txt

deleted100644 → 0

+0 −94

Original line number	Diff line number	Diff line
		Watchdog Timer Interfaces For The Linux Operating System

		Alan Cox <alan@lxorguk.ukuu.org.uk>

		Custom Linux Driver And Program Development


		The following watchdog drivers are currently implemented:

		ICS WDT501-P
		ICS WDT501-P (no fan tachometer)
		ICS WDT500-P
		Software Only
		SA1100 Internal Watchdog
		Berkshire Products PC Watchdog Revision A & C (by Ken Hollis)


		All six interfaces provide /dev/watchdog, which when open must be written
		to within a timeout or the machine will reboot. Each write delays the reboot
		time another timeout. In the case of the software watchdog the ability to
		reboot will depend on the state of the machines and interrupts. The hardware
		boards physically pull the machine down off their own onboard timers and
		will reboot from almost anything.

		A second temperature monitoring interface is available on the WDT501P cards
		and some Berkshire cards. This provides /dev/temperature. This is the machine
		internal temperature in degrees Fahrenheit. Each read returns a single byte
		giving the temperature.

		The third interface logs kernel messages on additional alert events.

		Both software and hardware watchdog drivers are available in the standard
		kernel. If you are using the software watchdog, you probably also want
		to use "panic=60" as a boot argument as well.

		The wdt card cannot be safely probed for. Instead you need to pass
		wdt=ioaddr,irq as a boot parameter - eg "wdt=0x240,11".

		The SA1100 watchdog module can be configured with the "sa1100_margin"
		commandline argument which specifies timeout value in seconds.

		The i810 TCO watchdog modules can be configured with the "i810_margin"
		commandline argument which specifies the counter initial value. The counter
		is decremented every 0.6 seconds and default to 50 (30 seconds). Values can
		range between 3 and 63.

		The i810 TCO watchdog driver also implements the WDIOC_GETSTATUS and
		WDIOC_GETBOOTSTATUS ioctl()s. WDIOC_GETSTATUS returns the actual counter value
		and WDIOC_GETBOOTSTATUS returns the value of TCO2 Status Register (see Intel's
		documentation for the 82801AA and 82801AB datasheet).

		Features
		--------
		WDT501P WDT500P Software Berkshire i810 TCO SA1100WD
		Reboot Timer X X X X X X
		External Reboot X X o o o X
		I/O Port Monitor o o o X o o
		Temperature X o o X o o
		Fan Speed X o o o o o
		Power Under X o o o o o
		Power Over X o o o o o
		Overheat X o o o o o

		The external event interfaces on the WDT boards are not currently supported.
		Minor numbers are however allocated for it.


		Example Watchdog Driver: see Documentation/watchdog/src/watchdog-simple.c


		Contact Information

		People keep asking about the WDT watchdog timer hardware: The phone contacts
		for Industrial Computer Source are:

		Industrial Computer Source
		http://www.indcompsrc.com
		ICS Advent, San Diego
		6260 Sequence Dr.
		San Diego, CA 92121-4371
		Phone (858) 677-0877
		FAX: (858) 677-0895
		>
		ICS Advent Europe, UK
		Oving Road
		Chichester,
		West Sussex,
		PO19 4ET, UK
		Phone: 00.44.1243.533900


		and please mention Linux when enquiring.

		For full information about the PCWD cards see the pcwd-watchdog.txt document.

Documentation/watchdog/wdt.txt

0 → 100644

+43 −0

Original line number	Diff line number	Diff line
		Last Reviewed: 10/05/2007

		WDT Watchdog Timer Interfaces For The Linux Operating System
		Alan Cox <alan@lxorguk.ukuu.org.uk>

		ICS WDT501-P
		ICS WDT501-P (no fan tachometer)
		ICS WDT500-P

		All the interfaces provide /dev/watchdog, which when open must be written
		to within a timeout or the machine will reboot. Each write delays the reboot
		time another timeout. In the case of the software watchdog the ability to
		reboot will depend on the state of the machines and interrupts. The hardware
		boards physically pull the machine down off their own onboard timers and
		will reboot from almost anything.

		A second temperature monitoring interface is available on the WDT501P cards
		This provides /dev/temperature. This is the machine internal temperature in
		degrees Fahrenheit. Each read returns a single byte giving the temperature.

		The third interface logs kernel messages on additional alert events.

		The wdt card cannot be safely probed for. Instead you need to pass
		wdt=ioaddr,irq as a boot parameter - eg "wdt=0x240,11".

		Features
		--------
		WDT501P WDT500P
		Reboot Timer X X
		External Reboot X X
		I/O Port Monitor o o
		Temperature X o
		Fan Speed X o
		Power Under X o
		Power Over X o
		Overheat X o

		The external event interfaces on the WDT boards are not currently supported.
		Minor numbers are however allocated for it.


		Example Watchdog Driver: see Documentation/watchdog/src/watchdog-simple.c