Documentation/watchdog/pcwd-watchdog.txt

   1                      Berkshire Products PC Watchdog Card
   2                    Support for ISA Cards  Revision A and C
   3            Documentation and Driver by Ken Hollis <kenji@bitgate.com>
   4
   5  The PC Watchdog is a card that offers the same type of functionality that
   6  the WDT card does, only it doesn't require an IRQ to run.  Furthermore,
   7  the Revision C card allows you to monitor any IO Port to automatically
   8  trigger the card into being reset.  This way you can make the card
   9  monitor hard drive status, or anything else you need.
  10
  11  The Watchdog Driver has one basic role: to talk to the card and send
  12  signals to it so it doesn't reset your computer ... at least during
  13  normal operation.
  14
  15  The Watchdog Driver will automatically find your watchdog card, and will
  16  attach a running driver for use with that card.  After the watchdog
  17  drivers have initialized, you can then talk to the card using the PC
  18  Watchdog program, available from http://ftp.bitgate.com/pcwd/.
  19
  20  I suggest putting a "watchdog -d" before the beginning of an fsck, and
  21  a "watchdog -e -t 1" immediately after the end of an fsck.  (Remember
  22  to run the program with an "&" to run it in the background!)
  23
  24  If you want to write a program to be compatible with the PC Watchdog
  25  driver, simply do the following:
  26
  27 -- Snippet of code --
  28 /*
  29  * Watchdog Driver Test Program
  30  */
  31
  32 #include <stdio.h>
  33 #include <stdlib.h>
  34 #include <string.h>
  35 #include <unistd.h>
  36 #include <fcntl.h>
  37 #include <sys/ioctl.h>
  38 #include <linux/types.h>
  39 #include <linux/watchdog.h>
  40
  41 int fd;
  42
  43 /*
  44  * This function simply sends an IOCTL to the driver, which in turn ticks
  45  * the PC Watchdog card to reset its internal timer so it doesn't trigger
  46  * a computer reset.
  47  */
  48 void keep_alive(void)
  49 {
  50     int dummy;
  51
  52     ioctl(fd, WDIOC_KEEPALIVE, &dummy);
  53 }
  54
  55 /*
  56  * The main program.  Run the program with "-d" to disable the card,
  57  * or "-e" to enable the card.
  58  */
  59 int main(int argc, char *argv[])
  60 {
  61     fd = open("/dev/watchdog", O_WRONLY);
  62
  63     if (fd == -1) {
  64         fprintf(stderr, "Watchdog device not enabled.\n");
  65         fflush(stderr);
  66         exit(-1);
  67     }
  68
  69     if (argc > 1) {
  70         if (!strncasecmp(argv[1], "-d", 2)) {
  71             ioctl(fd, WDIOC_SETOPTIONS, WDIOS_DISABLECARD);
  72             fprintf(stderr, "Watchdog card disabled.\n");
  73             fflush(stderr);
  74             exit(0);
  75         } else if (!strncasecmp(argv[1], "-e", 2)) {
  76             ioctl(fd, WDIOC_SETOPTIONS, WDIOS_ENABLECARD);
  77             fprintf(stderr, "Watchdog card enabled.\n");
  78             fflush(stderr);
  79             exit(0);
  80         } else {
  81             fprintf(stderr, "-d to disable, -e to enable.\n");
  82             fprintf(stderr, "run by itself to tick the card.\n");
  83             fflush(stderr);
  84             exit(0);
  85         }
  86     } else {
  87         fprintf(stderr, "Watchdog Ticking Away!\n");
  88         fflush(stderr);
  89     }
  90
  91     while(1) {
  92         keep_alive();
  93         sleep(1);
  94     }
  95 }
  96 -- End snippet --
  97
  98  Other IOCTL functions include:
  99
 100         WDIOC_GETSUPPORT
 101                 This returns the support of the card itself.  This
 102                 returns in structure "PCWDS" which returns:
 103                         options = WDIOS_TEMPPANIC
 104                                   (This card supports temperature)
 105                         firmware_version = xxxx
 106                                   (Firmware version of the card)
 107
 108         WDIOC_GETSTATUS
 109                 This returns the status of the card, with the bits of
 110                 WDIOF_* bitwise-anded into the value.  (The comments
 111                 are in linux/pcwd.h)
 112
 113         WDIOC_GETBOOTSTATUS
 114                 This returns the status of the card that was reported
 115                 at bootup.
 116
 117         WDIOC_GETTEMP
 118                 This returns the temperature of the card.  (You can also
 119                 read /dev/watchdog, which gives a temperature update
 120                 every second.)
 121
 122         WDIOC_SETOPTIONS
 123                 This lets you set the options of the card.  You can either
 124                 enable or disable the card this way.
 125
 126         WDIOC_KEEPALIVE
 127                 This pings the card to tell it not to reset your computer.
 128
 129  And that's all she wrote!
 130
 131  -- Ken Hollis
 132     (kenji@bitgate.com)
 133
 134 (This documentation may be out of date.  Check
 135  http://ftp.bitgate.com/pcwd/ for the absolute latest additions.)