TBB: add Trusted Watchdog support on ARM platforms

This patch adds watchdog support on ARM platforms (FVP and Juno).
A secure instance of SP805 is used as Trusted Watchdog. It is
entirely managed in BL1, being enabled in the early platform setup
hook and disabled in the exit hook. By default, the watchdog is
enabled in every build (even when TBB is disabled).

A new ARM platform specific build option `ARM_DISABLE_TRUSTED_WDOG`
has been introduced to allow the user to disable the watchdog at
build time. This feature may be used for testing or debugging
purposes.

Specific error handlers for Juno and FVP are also provided in this
patch. These handlers will be called after an image load or
authentication error. On FVP, the Table of Contents (ToC) in the FIP
is erased. On Juno, the corresponding error code is stored in the
V2M Non-Volatile flags register. In both cases, the CPU spins until
a watchdog reset is generated after 256 seconds (as specified in
the TBBR document).

Change-Id: I9ca11dcb0fe15af5dbc5407ab3cf05add962f4b4
diff --git a/include/plat/arm/board/common/v2m_def.h b/include/plat/arm/board/common/v2m_def.h
index 7a4ef5a..7ed0af6 100644
--- a/include/plat/arm/board/common/v2m_def.h
+++ b/include/plat/arm/board/common/v2m_def.h
@@ -38,6 +38,9 @@
 #define V2M_SYS_ID			0x0
 #define V2M_SYS_SWITCH			0x4
 #define V2M_SYS_LED			0x8
+#define V2M_SYS_NVFLAGS			0x38
+#define V2M_SYS_NVFLAGSSET		0x38
+#define V2M_SYS_NVFLAGSCLR		0x3c
 #define V2M_SYS_CFGDATA			0xa0
 #define V2M_SYS_CFGCTRL			0xa4
 #define V2M_SYS_CFGSTATUS		0xa8
@@ -109,7 +112,11 @@
 #define V2M_SP804_TIMER0_BASE		0x1C110000
 #define V2M_SP804_TIMER1_BASE		0x1C120000
 
-#define V2M_MAP_FLASH0			MAP_REGION_FLAT(V2M_FLASH0_BASE,\
+#define V2M_MAP_FLASH0_RW		MAP_REGION_FLAT(V2M_FLASH0_BASE,\
+						V2M_FLASH0_SIZE,	\
+						MT_DEVICE | MT_RW | MT_SECURE)
+
+#define V2M_MAP_FLASH0_RO		MAP_REGION_FLAT(V2M_FLASH0_BASE,\
 						V2M_FLASH0_SIZE,	\
 						MT_MEMORY | MT_RO | MT_SECURE)