diff options
Diffstat (limited to 'Documentation/watchdog')
| -rw-r--r-- | Documentation/watchdog/pcwd-watchdog.txt | 135 | ||||
| -rw-r--r-- | Documentation/watchdog/watchdog-api.txt | 399 | ||||
| -rw-r--r-- | Documentation/watchdog/watchdog.txt | 115 |
3 files changed, 649 insertions, 0 deletions
diff --git a/Documentation/watchdog/pcwd-watchdog.txt b/Documentation/watchdog/pcwd-watchdog.txt new file mode 100644 index 00000000000..12187a33e31 --- /dev/null +++ b/Documentation/watchdog/pcwd-watchdog.txt @@ -0,0 +1,135 @@ + Berkshire Products PC Watchdog Card + Support for ISA Cards Revision A and C + Documentation and Driver by Ken Hollis <kenji@bitgate.com> + + The PC Watchdog is a card that offers the same type of functionality that + the WDT card does, only it doesn't require an IRQ to run. Furthermore, + the Revision C card allows you to monitor any IO Port to automatically + trigger the card into being reset. This way you can make the card + monitor hard drive status, or anything else you need. + + The Watchdog Driver has one basic role: to talk to the card and send + signals to it so it doesn't reset your computer ... at least during + normal operation. + + 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/. + + 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 + to run the program with an "&" to run it in the background!) + + If you want to write a program to be compatible with the PC Watchdog + driver, simply do the following: + +-- Snippet of code -- +/* + * Watchdog Driver Test Program + */ + +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <unistd.h> +#include <fcntl.h> +#include <sys/ioctl.h> +#include <linux/types.h> +#include <linux/watchdog.h> + +int fd; + +/* + * This function simply sends an IOCTL to the driver, which in turn ticks + * the PC Watchdog card to reset its internal timer so it doesn't trigger + * a computer reset. + */ +void keep_alive(void) +{ + int dummy; + + ioctl(fd, WDIOC_KEEPALIVE, &dummy); +} + +/* + * The main program. Run the program with "-d" to disable the card, + * or "-e" to enable the card. + */ +int main(int argc, char *argv[]) +{ + fd = open("/dev/watchdog", O_WRONLY); + + if (fd == -1) { + fprintf(stderr, "Watchdog device not enabled.\n"); + fflush(stderr); + exit(-1); + } + + if (argc > 1) { + if (!strncasecmp(argv[1], "-d", 2)) { + ioctl(fd, WDIOC_SETOPTIONS, WDIOS_DISABLECARD); + fprintf(stderr, "Watchdog card disabled.\n"); + fflush(stderr); + exit(0); + } else if (!strncasecmp(argv[1], "-e", 2)) { + ioctl(fd, WDIOC_SETOPTIONS, WDIOS_ENABLECARD); + fprintf(stderr, "Watchdog card enabled.\n"); + fflush(stderr); + exit(0); + } else { + fprintf(stderr, "-d to disable, -e to enable.\n"); + fprintf(stderr, "run by itself to tick the card.\n"); + fflush(stderr); + exit(0); + } + } else { + fprintf(stderr, "Watchdog Ticking Away!\n"); + fflush(stderr); + } + + while(1) { + keep_alive(); + sleep(1); + } +} +-- End snippet -- + + Other IOCTL functions include: + + WDIOC_GETSUPPORT + This returns the support of the card itself. This + returns in structure "PCWDS" which returns: + options = WDIOS_TEMPPANIC + (This card supports temperature) + firmware_version = xxxx + (Firmware version of the card) + + WDIOC_GETSTATUS + This returns the status of the card, with the bits of + WDIOF_* bitwise-anded into the value. (The comments + are in linux/pcwd.h) + + WDIOC_GETBOOTSTATUS + This returns the status of the card that was reported + at bootup. + + WDIOC_GETTEMP + This returns the temperature of the card. (You can also + read /dev/watchdog, which gives a temperature update + every second.) + + WDIOC_SETOPTIONS + This lets you set the options of the card. You can either + enable or disable the card this way. + + WDIOC_KEEPALIVE + This pings the card to tell it not to reset your computer. + + And that's all she wrote! + + -- Ken Hollis + (kenji@bitgate.com) + +(This documentation may be out of date. Check + http://ftp.bitgate.com/pcwd/ for the absolute latest additions.) diff --git a/Documentation/watchdog/watchdog-api.txt b/Documentation/watchdog/watchdog-api.txt new file mode 100644 index 00000000000..28388aa700c --- /dev/null +++ b/Documentation/watchdog/watchdog-api.txt @@ -0,0 +1,399 @@ +The Linux Watchdog driver API. + +Copyright 2002 Christer Weingel <wingel@nano-system.com> + +Some parts of this document are copied verbatim from the sbc60xxwdt +driver which is (c) Copyright 2000 Jakob Oestergaard <jakob@ostenfeld.dk> + +This document describes the state of the Linux 2.4.18 kernel. + +Introduction: + +A Watchdog Timer (WDT) is a hardware circuit that can reset the +computer system in case of a software fault. You probably knew that +already. + +Usually a userspace daemon will notify the kernel watchdog driver via the +/dev/watchdog special device file that userspace is still alive, at +regular intervals. When such a notification occurs, the driver will +usually tell the hardware watchdog that everything is in order, and +that the watchdog should wait for yet another little while to reset +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 +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. + +The simplest API: + +All drivers support the basic mode of operation, where the watchdog +activates as soon as /dev/watchdog is opened and will reboot unless +the watchdog is pinged within a certain time, this time is called the +timeout or margin. The simplest way to ping the watchdog is to write +some data to the device. So a very simple watchdog daemon would look +like this: + +int main(int argc, const char *argv[]) { + int fd=open("/dev/watchdog",O_WRONLY); + if (fd==-1) { + perror("watchdog"); + exit(1); + } + while(1) { + write(fd, "\0", 1); + sleep(10); + } +} + +A more advanced driver could for example check that a HTTP server is +still responding before doing the write call to ping the watchdog. + +When the device is closed, the watchdog is disabled. This is not +always such a good idea, since if there is a bug in the watchdog +daemon and it crashes the system will not reboot. Because of this, +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 dameon crashes, the system +will reboot after the timeout has passed. + +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. + +The ioctl API: + +All conforming drivers also support an ioctl API. + +Pinging the watchdog using an ioctl: + +All drivers that have an ioctl interface support at least one ioctl, +KEEPALIVE. This ioctl does exactly the same thing as a write to the +watchdog device, so the main loop in the above program could be +replaced with: + + while (1) { + ioctl(fd, WDIOC_KEEPALIVE, 0); + sleep(10); + } + +the argument to the ioctl is ignored. + +Setting and getting the timeout: + +For some drivers it is possible to modify the watchdog timeout on the +fly with the SETTIMEOUT ioctl, those drivers have the WDIOF_SETTIMEOUT +flag set in their option field. The argument is an integer +representing the timeout in seconds. The driver returns the real +timeout used in the same variable, and this timeout might differ from +the requested one due to limitation of the hardware. + + int timeout = 45; + ioctl(fd, WDIOC_SETTIMEOUT, &timeout); + printf("The timeout was set to %d seconds\n", timeout); + +This example might actually print "The timeout was set to 60 seconds" +if the device has a granularity of minutes for its timeout. + +Starting with the Linux 2.4.18 kernel, it is possible to query the +current timeout using the GETTIMEOUT ioctl. + + ioctl(fd, WDIOC_GETTIMEOUT, &timeout); + printf("The timeout was is %d seconds\n", timeout); + +Envinronmental monitoring: + +All watchdog drivers are required return more information about the system, +some do temperature, fan and power level monitoring, some can tell you +the reason for the last reboot of the system. The GETSUPPORT ioctl is +available to ask what the device can do: + + struct watchdog_info ident; + ioctl(fd, WDIOC_GETSUPPORT, &ident); + +the fields returned in the ident struct are: + + identity a string identifying the watchdog driver + firmware_version the firmware version of the card if available + options a flags describing what the device supports + +the options field can have the following bits set, and describes what +kind of information that the GET_STATUS and GET_BOOT_STATUS ioctls can +return. [FIXME -- Is this correct?] + + WDIOF_OVERHEAT Reset due to CPU overheat + +The machine was last rebooted by the watchdog because the thermal limit was +exceeded + + WDIOF_FANFAULT Fan failed + +A system fan monitored by the watchdog card has failed + + WDIOF_EXTERN1 External relay 1 + +External monitoring relay/source 1 was triggered. Controllers intended for +real world applications include external monitoring pins that will trigger +a reset. + + WDIOF_EXTERN2 External relay 2 + +External monitoring relay/source 2 was triggered + + WDIOF_POWERUNDER Power bad/power fault + +The machine is showing an undervoltage status + + WDIOF_CARDRESET Card previously reset the CPU + +The last reboot was caused by the watchdog card + + WDIOF_POWEROVER Power over voltage + +The machine is showing an overvoltage status. Note that if one level is +under and one over both bits will be set - this may seem odd but makes +sense. + + WDIOF_KEEPALIVEPING Keep alive ping reply + +The watchdog saw a keepalive ping since it was last queried. + + WDIOF_SETTIMEOUT Can set/get the timeout + + +For those drivers that return any bits set in the option field, the +GETSTATUS and GETBOOTSTATUS ioctls can be used to ask for the current +status, and the status at the last reboot, respectively. + + int flags; + ioctl(fd, WDIOC_GETSTATUS, &flags); + + or + + ioctl(fd, WDIOC_GETBOOTSTATUS, &flags); + +Note that not all devices support these two calls, and some only +support the GETBOOTSTATUS call. + +Some drivers can measure the temperature using the GETTEMP ioctl. The +returned value is the temperature in degrees farenheit. + + int temperature; + ioctl(fd, WDIOC_GETTEMP, &temperature); + +Finally the SETOPTIONS ioctl can be used to control some aspects of +the cards operation; right now the pcwd driver is the only one +supporting thiss ioctl. + + int options = 0; + ioctl(fd, WDIOC_SETOPTIONS, options); + +The following options are available: + + WDIOS_DISABLECARD Turn off the watchdog timer + WDIOS_ENABLECARD Turn on the watchdog timer + WDIOS_TEMPPANIC Kernel panic on temperature trip + +[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?] + +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. + diff --git a/Documentation/watchdog/watchdog.txt b/Documentation/watchdog/watchdog.txt new file mode 100644 index 00000000000..dffda29c879 --- /dev/null +++ b/Documentation/watchdog/watchdog.txt @@ -0,0 +1,115 @@ + 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 +----------------------- + +#include <stdio.h> +#include <unistd.h> +#include <fcntl.h> + +int main(int argc, const char *argv[]) +{ + int fd=open("/dev/watchdog",O_WRONLY); + if(fd==-1) + { + perror("watchdog"); + exit(1); + } + while(1) + { + write(fd,"\0",1); + fsync(fd); + sleep(10); + } +} + + +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. |