Eliminate psci_suspend_context array

psci_suspend_context is an array of cache-line aligned structures
containing the single power_state integer per cpu. This array is
the only structure indexed by the aff_map_node.data integer.

This patch saves 2KB of BL3-1 memory by placing the CPU
power_state value directly in the aff_map_node structure. As a
result, this value is now never cached and the cache clean when
writing the value is no longer required.

Fixes ARM-software/tf-issues#195

Change-Id: Ib4c70c8f79eed295ea541e7827977a588a19ef9b

services/std_svc/psci/psci_afflvl_suspend.c

@@ -57,16 +57,11 @@ void psci_set_suspend_power_state(aff_map_node_t *node, unsigned int power_state
 	assert(node->mpidr == (read_mpidr() & MPIDR_AFFINITY_MASK));
 	assert(node->level == MPIDR_AFFLVL0);
 
-	/* Save PSCI power state parameter for the core in suspend context */
-	psci_suspend_context[node->data].power_state = power_state;
-
 	/*
-	 * Flush the suspend data to PoC since it will be accessed while
-	 * returning back from suspend with the caches turned off
+	 * Save PSCI power state parameter for the core in suspend context.
+	 * The node is in always-coherent RAM so it does not need to be flushed
 	 */
-	flush_dcache_range(
-		(unsigned long)&psci_suspend_context[node->data],
-		sizeof(suspend_context_t));
+	node->power_state = power_state;
 }
 
 /*******************************************************************************
@@ -97,7 +92,7 @@ int psci_get_aff_map_node_suspend_afflvl(aff_map_node_t *node)
 
 	assert(node->level == MPIDR_AFFLVL0);
 
-	power_state = psci_suspend_context[node->data].power_state;
+	power_state = node->power_state;
 	return ((power_state == PSCI_INVALID_DATA) ?
 				power_state : psci_get_pstate_afflvl(power_state));
 }
@@ -117,7 +112,7 @@ int psci_get_suspend_stateid(unsigned long mpidr)
 	assert(node);
 	assert(node->level == MPIDR_AFFLVL0);
 
-	power_state = psci_suspend_context[node->data].power_state;
+	power_state = node->power_state;
 	return ((power_state == PSCI_INVALID_DATA) ?
 					power_state : psci_get_pstate_id(power_state));
 }

services/std_svc/psci/psci_common.c

@@ -45,13 +45,6 @@
  */
 const spd_pm_ops_t *psci_spd_pm;
 
-/*******************************************************************************
- * Arrays that contains information needs to resume a cpu's execution when woken
- * out of suspend or off states. Each cpu is allocated a single entry in each
- * array during startup.
- ******************************************************************************/
-suspend_context_t psci_suspend_context[PSCI_NUM_AFFS];
-
 /*******************************************************************************
  * Grand array that holds the platform's topology information for state
  * management of affinity instances. Each node (aff_map_node) in the array

services/std_svc/psci/psci_private.h

@@ -44,7 +44,7 @@ typedef struct aff_map_node {
 	unsigned short ref_count;
 	unsigned char state;
 	unsigned char level;
-	unsigned int data;
+	unsigned int power_state;
 	bakery_lock_t lock;
 } aff_map_node_t;
 
@@ -53,14 +53,6 @@ typedef struct aff_limits_node {
 	int max;
 } aff_limits_node_t;
 
-/*******************************************************************************
- * This data structure holds secure world context that needs to be preserved
- * across cpu_suspend calls which enter the power down state.
- ******************************************************************************/
-typedef struct suspend_context {
-	unsigned int power_state;
-} __aligned(CACHE_WRITEBACK_GRANULE) suspend_context_t;
-
 typedef aff_map_node_t (*mpidr_aff_map_nodes_t[MPIDR_MAX_AFFLVL]);
 typedef unsigned int (*afflvl_power_on_finisher_t)(unsigned long,
 						 aff_map_node_t *);
@@ -68,7 +60,6 @@ typedef unsigned int (*afflvl_power_on_finisher_t)(unsigned long,
 /*******************************************************************************
  * Data prototypes
  ******************************************************************************/
-extern suspend_context_t psci_suspend_context[PSCI_NUM_AFFS];
 extern const plat_pm_ops_t *psci_plat_pm_ops;
 extern aff_map_node_t psci_aff_map[PSCI_NUM_AFFS];
 

services/std_svc/psci/psci_setup.c

@@ -57,12 +57,6 @@ static cpu_context_t psci_ns_context[PLATFORM_CORE_COUNT];
  ******************************************************************************/
 static aff_limits_node_t psci_aff_limits[MPIDR_MAX_AFFLVL + 1];
 
-/*******************************************************************************
- * 'psci_ns_einfo_idx' keeps track of the next free index in the
- * 'psci_suspend_context' arrays.
- ******************************************************************************/
-static unsigned int psci_ns_einfo_idx;
-
 /*******************************************************************************
  * Routines for retrieving the node corresponding to an affinity level instance
  * in the mpidr. The first one uses binary search to find the node corresponding
@@ -195,13 +189,8 @@ static void psci_init_aff_map_node(unsigned long mpidr,
 		if (state & PSCI_AFF_PRESENT)
 			psci_set_state(&psci_aff_map[idx], PSCI_STATE_OFF);
 
-		/* Ensure that we have not overflowed the psci_ns_einfo array */
-		assert(psci_ns_einfo_idx < PSCI_NUM_AFFS);
-
-		psci_aff_map[idx].data = psci_ns_einfo_idx;
 		/* Invalidate the suspend context for the node */
-		psci_suspend_context[psci_ns_einfo_idx].power_state = PSCI_INVALID_DATA;
-		psci_ns_einfo_idx++;
+		psci_aff_map[idx].power_state = PSCI_INVALID_DATA;
 
 		/*
 		 * Associate a non-secure context with this affinity
@@ -301,7 +290,6 @@ int32_t psci_setup(void)
 	int afflvl, affmap_idx, max_afflvl;
 	aff_map_node_t *node;
 
-	psci_ns_einfo_idx = 0;
 	psci_plat_pm_ops = NULL;
 
 	/* Find out the maximum affinity level that the platform implements */