Correctly dimension the PSCI aff_map_node array

The array of affinity nodes is currently allocated for 32 entries
with the PSCI_NUM_AFFS value defined in psci.h. This is not enough
for large systems, and will substantially over allocate the array
for small systems.

This patch introduces an optional platform definition
PLATFORM_NUM_AFFS to platform_def.h. If defined this value is
used for PSCI_NUM_AFFS, otherwise a value of two times the number
of CPU cores is used.

The FVP port defines PLATFORM_NUM_AFFS to be 10 which saves
nearly 1.5KB of memory.

Fixes ARM-software/tf-issues#192

Change-Id: I68e30ac950de88cfbd02982ba882a18fb69c1445

docs/porting-guide.md

@@ -150,6 +150,11 @@ file is found in [plat/fvp/include/platform_def.h].
     Defines the maximum number of CPUs that can be implemented within a cluster
     on the platform.
 
+*   **#define : PLATFORM_NUM_AFFS**
+
+    Defines the total number of nodes in the affinity heirarchy at all affinity
+    levels used by the platform.
+
 *   **#define : PRIMARY_CPU**
 
     Defines the `MPIDR` of the primary CPU on the platform. This value is used

include/bl31/services/psci.h

@@ -128,9 +128,6 @@
 #define psci_validate_power_state(pstate) (pstate & PSTATE_VALID_MASK)
 
 
-/* Number of affinity instances whose state this psci imp. can track */
-#define PSCI_NUM_AFFS		32ull
-
 #ifndef __ASSEMBLY__
 
 #include <stdint.h>

plat/fvp/include/platform_def.h

@@ -75,6 +75,8 @@
 #define PLATFORM_CORE_COUNT		(PLATFORM_CLUSTER1_CORE_COUNT + \
 						PLATFORM_CLUSTER0_CORE_COUNT)
 #define PLATFORM_MAX_CPUS_PER_CLUSTER	4
+#define PLATFORM_NUM_AFFS		(PLATFORM_CLUSTER_COUNT + \
+					 PLATFORM_CORE_COUNT)
 #define PRIMARY_CPU			0x0
 #define MAX_IO_DEVICES			3
 #define MAX_IO_HANDLES			4

services/std_svc/psci/psci_private.h

@@ -33,8 +33,16 @@
 
 #include <arch.h>
 #include <bakery_lock.h>
+#include <platform_def.h>	/* for PLATFORM_NUM_AFFS */
 #include <psci.h>
 
+/* Number of affinity instances whose state this psci imp. can track */
+#ifdef PLATFORM_NUM_AFFS
+#define PSCI_NUM_AFFS		PLATFORM_NUM_AFFS
+#else
+#define PSCI_NUM_AFFS		(2 * PLATFORM_CORE_COUNT)
+#endif
+
 /*******************************************************************************
  * The following two data structures hold the topology tree which in turn tracks
  * the state of the all the affinity instances supported by the platform.