feat(psci): add support for PSCI_SET_SUSPEND_MODE

This patch adds a PSCI_SET_SUSPEND_MODE handler that validates the
request per section 5.20.2 of the PSCI spec (DEN0022D.b), and updates
the suspend mode to the requested mode.

This is conditionally compiled into the build depending on the value of
the `PSCI_OS_INIT_MODE` build option.

Change-Id: Iebf65f5f7846aef6b8643ad6082db99b4dcc4bef
Signed-off-by: Wing Li <wingers@google.com>

1 files changed, 45 insertions, 0 deletions

diff --git a/lib/psci/psci_main.c b/lib/psci/psci_main.c
index a631f3ffb..4b5fc81d7 100644
--- a/lib/psci/psci_main.c
+++ b/lib/psci/psci_main.c
@@ -370,6 +370,39 @@ int psci_features(unsigned int psci_fid)
 	return PSCI_E_SUCCESS;
 }
 
+#if PSCI_OS_INIT_MODE
+int psci_set_suspend_mode(unsigned int mode)
+{
+	if (psci_suspend_mode == mode) {
+		return PSCI_E_SUCCESS;
+	}
+
+	if (mode == PLAT_COORD) {
+		/* Check if the current CPU is the last ON CPU in the system */
+		if (!psci_is_last_on_cpu_safe()) {
+			return PSCI_E_DENIED;
+		}
+	}
+
+	if (mode == OS_INIT) {
+		/*
+		 * Check if all CPUs in the system are ON or if the current
+		 * CPU is the last ON CPU in the system.
+		 */
+		if (!(psci_are_all_cpus_on_safe() ||
+		      psci_is_last_on_cpu_safe())) {
+			return PSCI_E_DENIED;
+		}
+	}
+
+	psci_suspend_mode = mode;
+	psci_flush_dcache_range((uintptr_t)&psci_suspend_mode,
+				sizeof(psci_suspend_mode));
+
+	return PSCI_E_SUCCESS;
+}
+#endif
+
 /*******************************************************************************
  * PSCI top level handler for servicing SMCs.
  ******************************************************************************/
@@ -453,6 +486,12 @@ u_register_t psci_smc_handler(uint32_t smc_fid,
 			ret = (u_register_t)psci_features(r1);
 			break;
 
+#if PSCI_OS_INIT_MODE
+		case PSCI_SET_SUSPEND_MODE:
+			ret = (u_register_t)psci_set_suspend_mode(r1);
+			break;
+#endif
+
 #if ENABLE_PSCI_STAT
 		case PSCI_STAT_RESIDENCY_AARCH32:
 			ret = psci_stat_residency(r1, r2);
@@ -515,6 +554,12 @@ u_register_t psci_smc_handler(uint32_t smc_fid,
 			ret = (u_register_t)psci_system_suspend(x1, x2);
 			break;
 
+#if PSCI_OS_INIT_MODE
+		case PSCI_SET_SUSPEND_MODE:
+			ret = (u_register_t)psci_set_suspend_mode(x1);
+			break;
+#endif
+
 #if ENABLE_PSCI_STAT
 		case PSCI_STAT_RESIDENCY_AARCH64:
 			ret = psci_stat_residency(x1, (unsigned int) x2);