powerpc/watchdog: Make default timeout for Book-E watchdog a Kconfig option

The PowerPC Book-E watchdog driver (booke_wdt.c) defines a default timeout
value in the code based on whether it's a Freescale Book-E part of not.
Instead of having hard-coded values in the driver, make it a Kconfig
option.

As newer chips gets faster, the current default values become less
appropriate, since the timeout sometimes occurs before the kernel finishes
booting.  Making the value a Kconfig option allows BSPs to configure a new
value without requiring the wdt_period command-line parameter to be set.
Signed-off-by: Timur Tabi <timur@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>

drivers/watchdog/Kconfig

@@ -966,6 +966,23 @@ config BOOKE_WDT
 	  Please see Documentation/watchdog/watchdog-api.txt for
 	  more information.
 
+config BOOKE_WDT_DEFAULT_TIMEOUT
+	int "PowerPC Book-E Watchdog Timer Default Timeout"
+	depends on BOOKE_WDT
+	default 38 if FSL_BOOKE
+	range 0 63 if FSL_BOOKE
+	default 3 if !FSL_BOOKE
+	range 0 3 if !FSL_BOOKE
+	help
+	  Select the default watchdog timer period to be used by the PowerPC
+	  Book-E watchdog driver.  A watchdog "event" occurs when the bit
+	  position represented by this number transitions from zero to one.
+
+	  For Freescale Book-E processors, this is a number between 0 and 63.
+	  For other Book-E processors, this is a number between 0 and 3.
+
+	  The value can be overidden by the wdt_period command-line parameter.
+
 # PPC64 Architecture
 
 config WATCHDOG_RTAS

drivers/watchdog/booke_wdt.c

@@ -33,14 +33,8 @@
  * occur, and the final time the board will reset.
  */
 
-#ifdef	CONFIG_FSL_BOOKE
-#define WDT_PERIOD_DEFAULT 38	/* Ex. wdt_period=28 bus=333Mhz,reset=~40sec */
-#else
-#define WDT_PERIOD_DEFAULT 3	/* Refer to the PPC40x and PPC4xx manuals */
-#endif				/* for timing information */
-
 u32 booke_wdt_enabled;
-u32 booke_wdt_period = WDT_PERIOD_DEFAULT;
+u32 booke_wdt_period = CONFIG_BOOKE_WDT_DEFAULT_TIMEOUT;
 
 #ifdef	CONFIG_FSL_BOOKE
 #define WDTP(x)		((((x)&0x3)<<30)|(((x)&0x3c)<<15))