The advantech boards have multiple watchdog types,
so this wasn't accepted as is into 2.4.
I updated the patch for 2.6 which was accepted.

diff -Naru linux-2.4.20/drivers/char/advantechwdt.c linux-2.4.20-pb/drivers/char/advantechwdt.c
--- linux-2.4.20/drivers/char/advantechwdt.c	2002-11-28 23:53:12.000000000 +0000
+++ linux-2.4.20-pb/drivers/char/advantechwdt.c	2003-10-14 15:48:30.000000000 +0100
@@ -22,6 +22,9 @@
  *
  *	14-Dec-2001 Matt Domsch <Matt_Domsch@dell.com>
  *	    Added nowayout module option to override CONFIG_WATCHDOG_NOWAYOUT
+ *
+ *	04-Oct-2003 Pádraig Brady <P@draigBrady.com>
+ *	    Changed to work on PCM-9578 (W83627HF)
  */
 
 #include <linux/config.h>
@@ -43,19 +46,10 @@
 static unsigned long advwdt_is_open;
 static char adv_expect_close;
 
-/*
- *	You must set these - there is no sane way to probe for this board.
- *
- *	To enable or restart, write the timeout value in seconds (1 to 63)
- *	to I/O port wdt_start.  To disable, read I/O port wdt_stop.
- *	Both are 0x443 for most boards (tested on a PCA-6276VE-00B1), but
- *	check your manual (at least the PCA-6159 seems to be different -
- *	the manual says wdt_stop is 0x43, not 0x443).
- *	(0x43 is also a write-only control register for the 8254 timer!)
- */
- 
-static int wdt_stop = 0x443;
-static int wdt_start = 0x443;
+static int wdt_io = 0x2E;
+#define WDT_EFER (wdt_io+0)   /* Extended Function Enable Registers */
+#define WDT_EFIR (wdt_io+0)   /* Extended Function Index Register (same as EFER) */
+#define WDT_EFDR (WDT_EFIR+1) /* Extended Function Data Register */
 
 static int wd_margin = 60; /* 60 sec default timeout */
 
@@ -76,14 +70,12 @@
 
 static int __init adv_setup(char *str)
 {
-	int ints[4];
+	int ints[3];
 
 	str = get_options(str, ARRAY_SIZE(ints), ints);
 
 	if(ints[0] > 0){
-		wdt_stop = ints[1];
-		if(ints[0] > 1)
-			wdt_start = ints[2];
+		wdt_io = ints[1];
 	}
 
 	return 1;
@@ -93,22 +85,36 @@
 
 #endif /* !MODULE */
 
-MODULE_PARM(wdt_stop, "i");
-MODULE_PARM_DESC(wdt_stop, "Advantech WDT 'stop' io port (default 0x443)");
-MODULE_PARM(wdt_start, "i");
-MODULE_PARM_DESC(wdt_start, "Advantech WDT 'start' io port (default 0x443)");
+MODULE_PARM(wdt_io, "i");
+MODULE_PARM_DESC(wdt_io, "Advantech WDT io port (default 0x2E)");
+
+static void
+advwdt_ctrl(int timeout)
+{
+	outb_p(0x87, WDT_EFER); /* Enter extended function mode */
+	outb_p(0x87, WDT_EFER); /* Again according to manual */
+
+	outb_p(0x07, WDT_EFER); /* point to logical device number reg */
+	outb_p(0x08, WDT_EFDR); /* select logical device 8 (GPIO2) */
+	outb_p(0x30, WDT_EFER); /* select CR30 */
+	outb_p(0x01, WDT_EFDR); /* set bit 0 to activate GPIO2 */
+
+	outb_p(0xF6, WDT_EFER);    /* Select CRF6 */
+	outb_p(timeout, WDT_EFDR); /* Write Timeout counter to CRF6 */
+
+	outb_p(0xAA, WDT_EFER); /* Leave extended function mode */
+}
 
 static void
 advwdt_ping(void)
 {
-	/* Write a watchdog value */
-	outb_p(wd_margin, wdt_start);
+	advwdt_ctrl(wd_margin);
 }
 
 static void
 advwdt_disable(void)
 {
-	inb_p(wdt_stop);
+	advwdt_ctrl(0);
 }
 
 static ssize_t
@@ -132,7 +138,7 @@
 					adv_expect_close = 42;
 			}
 		}
-			advwdt_ping();
+		advwdt_ping();
 	}
 	return count;
 }
@@ -278,9 +284,7 @@
 	printk(KERN_INFO "WDT driver for Advantech single board computer initialising.\n");
 
 	misc_register(&advwdt_miscdev);
-	if(wdt_stop != wdt_start)
-		request_region(wdt_stop, 1, "Advantech WDT");
-	request_region(wdt_start, 1, "Advantech WDT");
+	request_region(wdt_io, 1, "Advantech WDT");
 	register_reboot_notifier(&advwdt_notifier);
 	return 0;
 }
@@ -290,17 +294,15 @@
 {
 	misc_deregister(&advwdt_miscdev);
 	unregister_reboot_notifier(&advwdt_notifier);
-	if(wdt_stop != wdt_start)
-		release_region(wdt_stop,1);
-	release_region(wdt_start,1);
+	release_region(wdt_io,1);
 }
 
 module_init(advwdt_init);
 module_exit(advwdt_exit);
 
 MODULE_LICENSE("GPL");
-MODULE_AUTHOR("Marek Michalkiewicz <marekm@linux.org.pl>");
-MODULE_DESCRIPTION("Advantech Single Board Computer WDT driver");
+MODULE_AUTHOR("Pádraig Brady <P@draigBrady.com>");
+MODULE_DESCRIPTION("Advantech Single Board Computer (9578) WDT driver");
 EXPORT_NO_SYMBOLS;
 
 /* end of advantechwdt.c */