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Merge master.kernel.org:/pub/scm/linux/kernel/git/wim/linux-2.6-watchdog
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* master.kernel.org:/pub/scm/linux/kernel/git/wim/linux-2.6-watchdog:
  [WATCHDOG] Documentation/watchdog update
  [WATCHDOG] convert AT91RM9200 watchdog to platform driver
  [WATCHDOG] add WDIOC_GETTIMELEFT ioctl
  [WATCHDOG] Pre-Timeout flags
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Linus Torvalds committed Jun 28, 2006
2 parents b445979 + 56fb9e5 commit fffcb48
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Showing 10 changed files with 283 additions and 127 deletions.
75 changes: 3 additions & 72 deletions Documentation/watchdog/pcwd-watchdog.txt
Original file line number Diff line number Diff line change
Expand Up @@ -22,78 +22,9 @@
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 --
driver, simply use of modify the watchdog test program:
Documentation/watchdog/src/watchdog-test.c


Other IOCTL functions include:

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15 changes: 15 additions & 0 deletions Documentation/watchdog/src/watchdog-simple.c
Original file line number Diff line number Diff line change
@@ -0,0 +1,15 @@
#include <stdlib.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);
}
}
68 changes: 68 additions & 0 deletions Documentation/watchdog/src/watchdog-test.c
Original file line number Diff line number Diff line change
@@ -0,0 +1,68 @@
/*
* 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);
}
}
56 changes: 39 additions & 17 deletions Documentation/watchdog/watchdog-api.txt
Original file line number Diff line number Diff line change
Expand Up @@ -34,22 +34,7 @@ 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:

#include <stdlib.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);
sleep(10);
}
}
like this source file: see Documentation/watchdog/src/watchdog-simple.c

A more advanced driver could for example check that a HTTP server is
still responding before doing the write call to ping the watchdog.
Expand Down Expand Up @@ -110,7 +95,40 @@ current timeout using the GETTIMEOUT ioctl.
ioctl(fd, WDIOC_GETTIMEOUT, &timeout);
printf("The timeout was is %d seconds\n", timeout);

Envinronmental monitoring:
Pretimeouts:

Some watchdog timers can be set to have a trigger go off before the
actual time they will reset the system. This can be done with an NMI,
interrupt, or other mechanism. This allows Linux to record useful
information (like panic information and kernel coredumps) before it
resets.

pretimeout = 10;
ioctl(fd, WDIOC_SETPRETIMEOUT, &pretimeout);

Note that the pretimeout is the number of seconds before the time
when the timeout will go off. It is not the number of seconds until
the pretimeout. So, for instance, if you set the timeout to 60 seconds
and the pretimeout to 10 seconds, the pretimout will go of in 50
seconds. Setting a pretimeout to zero disables it.

There is also a get function for getting the pretimeout:

ioctl(fd, WDIOC_GETPRETIMEOUT, &timeout);
printf("The pretimeout was is %d seconds\n", timeout);

Not all watchdog drivers will support a pretimeout.

Get the number of seconds before reboot:

Some watchdog drivers have the ability to report the remaining time
before the system will reboot. The WDIOC_GETTIMELEFT is the ioctl
that returns the number of seconds before reboot.

ioctl(fd, WDIOC_GETTIMELEFT, &timeleft);
printf("The timeout was is %d seconds\n", timeleft);

Environmental monitoring:

All watchdog drivers are required return more information about the system,
some do temperature, fan and power level monitoring, some can tell you
Expand Down Expand Up @@ -169,6 +187,10 @@ The watchdog saw a keepalive ping since it was last queried.

WDIOF_SETTIMEOUT Can set/get the timeout

The watchdog can do pretimeouts.

WDIOF_PRETIMEOUT Pretimeout (in seconds), get/set


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
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23 changes: 1 addition & 22 deletions Documentation/watchdog/watchdog.txt
Original file line number Diff line number Diff line change
Expand Up @@ -65,28 +65,7 @@ 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);
}
}
Example Watchdog Driver: see Documentation/watchdog/src/watchdog-simple.c


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