Add PubSub events for CPU powerdown/powerup

The suspend hook is published at the start of a CPU powerdown
operation.  The resume hook is published at the end of a CPU powerup
operation.

Change-Id: I50c05e2dde0d33834095ac41b4fcea4c161bb434
Signed-off-by: Dimitris Papastamos <dimitris.papastamos@arm.com>

include/lib/el3_runtime/pubsub_events.h

@@ -17,6 +17,13 @@
  */
 REGISTER_PUBSUB_EVENT(psci_cpu_on_finish);
 
+/*
+ * These events are published before/after a CPU has been powered down/up
+ * via the PSCI CPU SUSPEND API.
+ */
+REGISTER_PUBSUB_EVENT(psci_suspend_pwrdown_start);
+REGISTER_PUBSUB_EVENT(psci_suspend_pwrdown_finish);
+
 #ifdef AARCH64
 /*
  * These events are published by the AArch64 context management framework

lib/psci/psci_suspend.c

@@ -14,6 +14,7 @@
 #include <debug.h>
 #include <platform.h>
 #include <pmf.h>
+#include <pubsub_events.h>
 #include <runtime_instr.h>
 #include <stddef.h>
 #include "psci_private.h"
@@ -68,6 +69,8 @@ static void psci_suspend_to_pwrdown_start(unsigned int end_pwrlvl,
 {
 	unsigned int max_off_lvl = psci_find_max_off_lvl(state_info);
 
+	PUBLISH_EVENT(psci_suspend_pwrdown_start);
+
 	/* Save PSCI target power level for the suspend finisher handler */
 	psci_set_suspend_pwrlvl(end_pwrlvl);
 
@@ -308,6 +311,8 @@ void psci_cpu_suspend_finish(unsigned int cpu_idx,
 	/* Invalidate the suspend level for the cpu */
 	psci_set_suspend_pwrlvl(PSCI_INVALID_PWR_LVL);
 
+	PUBLISH_EVENT(psci_suspend_pwrdown_finish);
+
 	/*
 	 * Generic management: Now we just need to retrieve the
 	 * information that we had stashed away during the suspend