[PATCH] ppc32: Added support for the Book-E style Watchdog Timer

PowerPC 40x and Book-E processors support a watchdog timer at the processor
core level.  The timer has implementation dependent timeout frequencies
that can be configured by software.

One the first Watchdog timeout we get a critical exception.  It is left to
board specific code to determine what should happen at this point.  If
nothing is done and another timeout period expires the processor may
attempt to reset the machine.

Command line parameters:
  wdt=0 : disable watchdog (default)
  wdt=1 : enable watchdog

  wdt_period=N : N sets the value of the Watchdog Timer Period.

  The Watchdog Timer Period meaning is implementation specific. Check
  User Manual for the processor for more details.

This patch is based off of work done by Takeharu Kato.

Signed-off-by: Matt McClintock <msm@freescale.com>
Signed-off-by: Kumar Gala <kumar.gala@freescale.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

Documentation/watchdog/watchdog-api.txt

@@ -228,6 +228,26 @@ advantechwdt.c -- Advantech Single Board Computer
 	The GETSTATUS call returns if the device is open or not.
 	[FIXME -- silliness again?]
 	
+booke_wdt.c -- PowerPC BookE Watchdog Timer
+
+	Timeout default varies according to frequency, supports
+	SETTIMEOUT
+
+	Watchdog can not be turned off, CONFIG_WATCHDOG_NOWAYOUT
+	does not make sense
+
+	GETSUPPORT returns the watchdog_info struct, and
+	GETSTATUS returns the supported options. GETBOOTSTATUS
+	returns a 1 if the last reset was caused by the
+	watchdog and a 0 otherwise. This watchdog can not be
+	disabled once it has been started. The wdt_period kernel
+	parameter selects which bit of the time base changing
+	from 0->1 will trigger the watchdog exception. Changing
+	the timeout from the ioctl calls will change the
+	wdt_period as defined above. Finally if you would like to
+	replace the default Watchdog Handler you can implement the
+	WatchdogHandler() function in your own code.
+
 eurotechwdt.c -- Eurotech CPU-1220/1410
 
 	The timeout can be set using the SETTIMEOUT ioctl and defaults