PSCI: Add SYSTEM_SUSPEND API support

This patch adds support for SYSTEM_SUSPEND API as mentioned in the PSCI 1.0
specification. This API, on being invoked on the last running core on a
supported platform, will put the system into a low power mode with memory
retention.

The psci_afflvl_suspend() internal API has been reused as most of the actions
to suspend a system are the same as invoking the PSCI CPU_SUSPEND API with the
target affinity level as 'system'. This API needs the 'power state' parameter
for the target low power state. This parameter is not passed by the caller of
the SYSTEM_SUSPEND API. Hence, the platform needs to implement the
get_sys_suspend_power_state() platform function to provide this information.
Also, the platform also needs to add support for suspending the system to the
existing 'plat_pm_ops' functions: affinst_suspend() and
affinst_suspend_finish().

Change-Id: Ib6bf10809cb4e9b92f463755608889aedd83cef5

4 files changed, 106 insertions, 4 deletions

diff --git a/services/std_svc/psci/psci_common.c b/services/std_svc/psci/psci_common.c
index 237cf1e9..e401609a 100644
--- a/services/std_svc/psci/psci_common.c
+++ b/services/std_svc/psci/psci_common.c
@@ -92,6 +92,38 @@ uint32_t psci_find_max_phys_off_afflvl(uint32_t start_afflvl,
 }
 
 /*******************************************************************************
+ * This function verifies that the all the other cores in the system have been
+ * turned OFF and the current CPU is the last running CPU in the system.
+ * Returns 1 (true) if the current CPU is the last ON CPU or 0 (false)
+ * otherwise.
+ ******************************************************************************/
+unsigned int psci_is_last_on_cpu(void)
+{
+	unsigned long mpidr = read_mpidr_el1() & MPIDR_AFFINITY_MASK;
+	unsigned int i;
+
+	for (i = psci_aff_limits[MPIDR_AFFLVL0].min;
+			i <= psci_aff_limits[MPIDR_AFFLVL0].max; i++) {
+
+		assert(psci_aff_map[i].level == MPIDR_AFFLVL0);
+
+		if (!(psci_aff_map[i].state & PSCI_AFF_PRESENT))
+			continue;
+
+		if (psci_aff_map[i].mpidr == mpidr) {
+			assert(psci_get_state(&psci_aff_map[i])
+					== PSCI_STATE_ON);
+			continue;
+		}
+
+		if (psci_get_state(&psci_aff_map[i]) != PSCI_STATE_OFF)
+			return 0;
+	}
+
+	return 1;
+}
+
+/*******************************************************************************
  * This function saves the highest affinity level which is in OFF state. The
  * affinity instance with which the level is associated is determined by the
  * caller.
diff --git a/services/std_svc/psci/psci_main.c b/services/std_svc/psci/psci_main.c
index fcd3b552..b389287b 100644
--- a/services/std_svc/psci/psci_main.c
+++ b/services/std_svc/psci/psci_main.c
@@ -31,9 +31,10 @@
 #include <arch.h>
 #include <arch_helpers.h>
 #include <assert.h>
+#include <debug.h>
+#include <platform.h>
 #include <runtime_svc.h>
 #include <std_svc.h>
-#include <debug.h>
 #include "psci_private.h"
 
 /*******************************************************************************
@@ -167,6 +168,62 @@ int psci_cpu_suspend(unsigned int power_state,
 	return PSCI_E_SUCCESS;
 }
 
+int psci_system_suspend(unsigned long entrypoint,
+			unsigned long context_id)
+{
+	int rc;
+	unsigned int power_state;
+	entry_point_info_t ep;
+
+	/* Validate the entrypoint using platform pm_ops */
+	if (psci_plat_pm_ops->validate_ns_entrypoint) {
+		rc = psci_plat_pm_ops->validate_ns_entrypoint(entrypoint);
+		if (rc != PSCI_E_SUCCESS) {
+			assert(rc == PSCI_E_INVALID_PARAMS);
+			return PSCI_E_INVALID_PARAMS;
+		}
+	}
+
+	/* Check if the current CPU is the last ON CPU in the system */
+	if (!psci_is_last_on_cpu())
+		return PSCI_E_DENIED;
+
+	/*
+	 * Verify and derive the re-entry information for
+	 * the non-secure world from the non-secure state from
+	 * where this call originated.
+	 */
+	rc = psci_get_ns_ep_info(&ep, entrypoint, context_id);
+	if (rc != PSCI_E_SUCCESS)
+		return rc;
+
+	/*
+	 * Assert that the required pm_ops hook is implemented to ensure that
+	 * the capability detected during psci_setup() is valid.
+	 */
+	assert(psci_plat_pm_ops->get_sys_suspend_power_state);
+
+	/*
+	 * Query the platform for the power_state required for system suspend
+	 */
+	power_state = psci_plat_pm_ops->get_sys_suspend_power_state();
+
+	/* Save PSCI power state parameter for the core in suspend context */
+	psci_set_suspend_power_state(power_state);
+
+	/*
+	 * Do what is needed to enter the power down state. Upon success,
+	 * enter the final wfi which will power down this cpu.
+	 */
+	psci_afflvl_suspend(&ep,
+			    MPIDR_AFFLVL0,
+			    PLATFORM_MAX_AFFLVL);
+
+	/* Reset PSCI power state parameter for the core. */
+	psci_set_suspend_power_state(PSCI_INVALID_DATA);
+	return PSCI_E_SUCCESS;
+}
+
 int psci_cpu_off(void)
 {
 	int rc;
@@ -357,6 +414,9 @@ uint64_t psci_smc_handler(uint32_t smc_fid,
 		case PSCI_MIG_INFO_UP_CPU_AARCH32:
 			SMC_RET1(handle, psci_migrate_info_up_cpu());
 
+		case PSCI_SYSTEM_SUSPEND_AARCH32:
+			SMC_RET1(handle, psci_system_suspend(x1, x2));
+
 		case PSCI_SYSTEM_OFF:
 			psci_system_off();
 			/* We should never return from psci_system_off() */
@@ -390,6 +450,9 @@ uint64_t psci_smc_handler(uint32_t smc_fid,
 		case PSCI_MIG_INFO_UP_CPU_AARCH64:
 			SMC_RET1(handle, psci_migrate_info_up_cpu());
 
+		case PSCI_SYSTEM_SUSPEND_AARCH64:
+			SMC_RET1(handle, psci_system_suspend(x1, x2));
+
 		default:
 			break;
 		}
diff --git a/services/std_svc/psci/psci_private.h b/services/std_svc/psci/psci_private.h
index 62a0efc8..2955de7a 100644
--- a/services/std_svc/psci/psci_private.h
+++ b/services/std_svc/psci/psci_private.h
@@ -69,7 +69,8 @@
 			define_psci_cap(PSCI_CPU_ON_AARCH64) |		\
 			define_psci_cap(PSCI_AFFINITY_INFO_AARCH64) |	\
 			define_psci_cap(PSCI_MIG_AARCH64) |		\
-			define_psci_cap(PSCI_MIG_INFO_UP_CPU_AARCH64))
+			define_psci_cap(PSCI_MIG_INFO_UP_CPU_AARCH64) |	\
+			define_psci_cap(PSCI_SYSTEM_SUSPEND_AARCH64))
 
 
 /*******************************************************************************
@@ -102,6 +103,7 @@ typedef void (*afflvl_power_on_finisher_t)(aff_map_node_t *);
  ******************************************************************************/
 extern const plat_pm_ops_t *psci_plat_pm_ops;
 extern aff_map_node_t psci_aff_map[PSCI_NUM_AFFS];
+extern aff_limits_node_t psci_aff_limits[MPIDR_MAX_AFFLVL + 1];
 extern uint32_t psci_caps;
 
 /*******************************************************************************
@@ -140,6 +142,7 @@ void psci_set_max_phys_off_afflvl(uint32_t afflvl);
 uint32_t psci_find_max_phys_off_afflvl(uint32_t start_afflvl,
 				       uint32_t end_afflvl,
 				       aff_map_node_t *mpidr_nodes[]);
+unsigned int psci_is_last_on_cpu(void);
 int psci_spd_migrate_info(uint64_t *mpidr);
 
 /* Private exported functions from psci_setup.c */
diff --git a/services/std_svc/psci/psci_setup.c b/services/std_svc/psci/psci_setup.c
index 5ff24d5b..01b559cf 100644
--- a/services/std_svc/psci/psci_setup.c
+++ b/services/std_svc/psci/psci_setup.c
@@ -55,7 +55,7 @@ static cpu_context_t psci_ns_context[PLATFORM_CORE_COUNT];
  * level i.e. start index and end index needs to be present. 'psci_aff_limits'
  * stores this information.
  ******************************************************************************/
-static aff_limits_node_t psci_aff_limits[MPIDR_MAX_AFFLVL + 1];
+aff_limits_node_t psci_aff_limits[MPIDR_MAX_AFFLVL + 1];
 
 /******************************************************************************
  * Define the psci capability variable.
@@ -385,8 +385,12 @@ int32_t psci_setup(void)
 		psci_caps |=  define_psci_cap(PSCI_CPU_OFF);
 	if (psci_plat_pm_ops->affinst_on && psci_plat_pm_ops->affinst_on_finish)
 		psci_caps |=  define_psci_cap(PSCI_CPU_ON_AARCH64);
-	if (psci_plat_pm_ops->affinst_suspend && psci_plat_pm_ops->affinst_suspend_finish)
+	if (psci_plat_pm_ops->affinst_suspend &&
+			psci_plat_pm_ops->affinst_suspend_finish) {
 		psci_caps |=  define_psci_cap(PSCI_CPU_SUSPEND_AARCH64);
+		if (psci_plat_pm_ops->get_sys_suspend_power_state)
+			psci_caps |=  define_psci_cap(PSCI_SYSTEM_SUSPEND_AARCH64);
+	}
 	if (psci_plat_pm_ops->system_off)
 		psci_caps |=  define_psci_cap(PSCI_SYSTEM_OFF);
 	if (psci_plat_pm_ops->system_reset)