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-rw-r--r--Documentation/watchdog/pcwd-watchdog.txt75
-rw-r--r--Documentation/watchdog/src/watchdog-simple.c15
-rw-r--r--Documentation/watchdog/src/watchdog-test.c68
-rw-r--r--Documentation/watchdog/watchdog-api.txt56
-rw-r--r--Documentation/watchdog/watchdog.txt23
5 files changed, 126 insertions, 111 deletions
diff --git a/Documentation/watchdog/pcwd-watchdog.txt b/Documentation/watchdog/pcwd-watchdog.txt
index 12187a33e310..d9ee6336c1d4 100644
--- a/Documentation/watchdog/pcwd-watchdog.txt
+++ b/Documentation/watchdog/pcwd-watchdog.txt
@@ -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:
diff --git a/Documentation/watchdog/src/watchdog-simple.c b/Documentation/watchdog/src/watchdog-simple.c
new file mode 100644
index 000000000000..85cf17c48669
--- /dev/null
+++ b/Documentation/watchdog/src/watchdog-simple.c
@@ -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);
+ }
+}
diff --git a/Documentation/watchdog/src/watchdog-test.c b/Documentation/watchdog/src/watchdog-test.c
new file mode 100644
index 000000000000..65f6c19cb865
--- /dev/null
+++ b/Documentation/watchdog/src/watchdog-test.c
@@ -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);
+ }
+}
diff --git a/Documentation/watchdog/watchdog-api.txt b/Documentation/watchdog/watchdog-api.txt
index 21ed51173662..958ff3d48be3 100644
--- a/Documentation/watchdog/watchdog-api.txt
+++ b/Documentation/watchdog/watchdog-api.txt
@@ -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.
@@ -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
@@ -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
diff --git a/Documentation/watchdog/watchdog.txt b/Documentation/watchdog/watchdog.txt
index dffda29c8799..4b1ff69cc19a 100644
--- a/Documentation/watchdog/watchdog.txt
+++ b/Documentation/watchdog/watchdog.txt
@@ -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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