lwmon5: enable hardware watchdog

Some boards (e.g. lwmon5) may use rather small watchdog intervals, so
causing it to reboot the board if U-Boot does a long busy-wait with
udelay(). Thus, for these boards we have to restart WD more
frequently.

This patch splits the busy-wait udelay() into smaller, predefined,
intervals, so that the watchdog timer may be resetted with the
configurable (CONFIG_WD_PERIOD) interval.

Signed-off-by: Yuri Tikhonov <yur@emcraft.com>

include/configs/lwmon5.h

@@ -366,12 +366,11 @@
 #define CFG_PCI_SUBSYS_VENDORID 0x10e8	/* AMCC				*/
 #define CFG_PCI_SUBSYS_ID       0xcafe	/* Whatever			*/
 
-#if 0
 /*
  * ToDo: Watchdog is not test fully, so exclude it for now
  */
 #define CONFIG_HW_WATCHDOG	1	/* Use external HW-Watchdog	*/
-#endif
+#define CONFIG_WD_PERIOD	40000	/* in usec */
 
 /*
  * For booting Linux, the board info and command line data

lib_ppc/time.c

@@ -23,6 +23,9 @@
 
 #include <common.h>
 
+#ifndef CONFIG_WD_PERIOD
+# define CONFIG_WD_PERIOD	(10 * 1000 * 1000)	/* 10 seconds default*/
+#endif
 
 /* ------------------------------------------------------------------------- */
 
@@ -53,9 +56,14 @@ unsigned long usec2ticks(unsigned long usec)
  */
 void udelay(unsigned long usec)
 {
-	ulong ticks = usec2ticks (usec);
-
-	wait_ticks (ticks);
+	ulong ticks, kv;
+
+	do {
+		kv = usec > CONFIG_WD_PERIOD ? CONFIG_WD_PERIOD : usec;
+		ticks = usec2ticks (kv);
+		wait_ticks (ticks);
+		usec -= kv;
+	} while(usec);
 }
 
 /* ------------------------------------------------------------------------- */