CSS: Allow system suspend only via PSCI SYSTEM_SUSPEND API

The CSS power management layer previously allowed to suspend system
power domain level via both PSCI CPU_SUSPEND and PSCI SYSTEM_SUSPEND
APIs. System suspend via PSCI CPU_SUSPEND was always problematic to
support because of issues with targeting wakeup interrupts to
suspended cores before the per-cpu GIC initialization is done. This
is not the case for PSCI SYSTEM_SUSPEND API because all the other
cores are expected to be offlined prior to issuing system suspend and
PSCI CPU_ON explicit calls will be made to power them on. Hence the Juno
platform used to downgrade the PSCI CPU_SUSPEND request for system
power domain level to cluster level by overriding the default
`plat_psci_pm_ops` exported by CSS layer.

Given the direction the new CSS platforms are evolving, it is best to
limit the system suspend only via PSCI SYSTEM_SUSPEND API for all
CSS platforms. This patch makes changes to allow system suspend
only via PSCI SYSTEM_SUSPEND API. The override of `plat_psci_ops`
for Juno is removed.

Change-Id: Idb30eaad04890dd46074e9e888caeedc50a4b533
Signed-off-by: Soby Mathew <soby.mathew@arm.com>

3 files changed, 46 insertions, 98 deletions

diff --git a/plat/arm/board/juno/juno_pm.c b/plat/arm/board/juno/juno_pm.c
deleted file mode 100644
index c0fa628e..00000000
--- a/plat/arm/board/juno/juno_pm.c
+++ /dev/null
@@ -1,93 +0,0 @@
-/*
- * Copyright (c) 2015-2016, ARM Limited and Contributors. All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are met:
- *
- * Redistributions of source code must retain the above copyright notice, this
- * list of conditions and the following disclaimer.
- *
- * Redistributions in binary form must reproduce the above copyright notice,
- * this list of conditions and the following disclaimer in the documentation
- * and/or other materials provided with the distribution.
- *
- * Neither the name of ARM nor the names of its contributors may be used
- * to endorse or promote products derived from this software without specific
- * prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
- * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
- * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
- * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
- * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
- * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
- * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
- * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
- * POSSIBILITY OF SUCH DAMAGE.
- */
-#include <css_pm.h>
-#include <plat_arm.h>
-
-/*
- * Custom `validate_power_state` handler for Juno. According to PSCI
- * Specification, interrupts targeted to cores in PSCI CPU SUSPEND should
- * be able to resume it. On Juno, when the system power domain is suspended,
- * the GIC is also powered down. The SCP resumes the final core to be suspend
- * when an external wake-up event is received. But the other cores cannot be
- * woken up by a targeted interrupt, because GIC doesn't forward these
- * interrupts to the SCP. Due to this hardware limitation, we down-grade PSCI
- * CPU SUSPEND requests targeted to the system power domain level
- * to cluster power domain level.
- *
- * The system power domain suspend on Juno is only supported only via
- * PSCI SYSTEM SUSPEND API.
- */
-static int juno_validate_power_state(unsigned int power_state,
-			    psci_power_state_t *req_state)
-{
-	int rc;
-	rc = arm_validate_power_state(power_state, req_state);
-
-	/*
-	 * Ensure that the system power domain level is never suspended
-	 * via PSCI CPU SUSPEND API. Currently system suspend is only
-	 * supported via PSCI SYSTEM SUSPEND API.
-	 */
-	req_state->pwr_domain_state[ARM_PWR_LVL2] = ARM_LOCAL_STATE_RUN;
-	return rc;
-}
-
-/*
- * Custom `translate_power_state_by_mpidr` handler for Juno. Unlike in the
- * `juno_validate_power_state`, we do not down-grade the system power
- * domain level request in `power_state` as it will be used to query the
- * PSCI_STAT_COUNT/RESIDENCY at the system power domain level.
- */
-static int juno_translate_power_state_by_mpidr(u_register_t mpidr,
-		unsigned int power_state,
-		psci_power_state_t *output_state)
-{
-	return arm_validate_power_state(power_state, output_state);
-}
-
-/*******************************************************************************
- * Export the platform handlers via plat_arm_psci_pm_ops. The ARM Standard
- * platform will take care of registering the handlers with PSCI.
- ******************************************************************************/
-plat_psci_ops_t plat_arm_psci_pm_ops = {
-	.pwr_domain_on			= css_pwr_domain_on,
-	.pwr_domain_on_finish		= css_pwr_domain_on_finish,
-	.pwr_domain_off			= css_pwr_domain_off,
-	.cpu_standby			= css_cpu_standby,
-	.pwr_domain_suspend		= css_pwr_domain_suspend,
-	.pwr_domain_suspend_finish	= css_pwr_domain_suspend_finish,
-	.system_off			= css_system_off,
-	.system_reset			= css_system_reset,
-	.validate_power_state		= juno_validate_power_state,
-	.validate_ns_entrypoint		= arm_validate_ns_entrypoint,
-	.get_sys_suspend_power_state	= css_get_sys_suspend_power_state,
-	.translate_power_state_by_mpidr = juno_translate_power_state_by_mpidr,
-	.get_node_hw_state		= css_node_hw_state
-};
diff --git a/plat/arm/board/juno/platform.mk b/plat/arm/board/juno/platform.mk
index 08554381..e29f8c86 100644
--- a/plat/arm/board/juno/platform.mk
+++ b/plat/arm/board/juno/platform.mk
@@ -73,7 +73,6 @@ BL2U_SOURCES		+=	${JUNO_SECURITY_SOURCES}
 BL31_SOURCES		+=	lib/cpus/aarch64/cortex_a53.S		\
 				lib/cpus/aarch64/cortex_a57.S		\
 				lib/cpus/aarch64/cortex_a72.S		\
-				plat/arm/board/juno/juno_pm.c		\
 				plat/arm/board/juno/juno_topology.c	\
 				${JUNO_GIC_SOURCES}			\
 				${JUNO_INTERCONNECT_SOURCES}		\
diff --git a/plat/arm/css/common/css_pm.c b/plat/arm/css/common/css_pm.c
index d4dd0af7..21ce8655 100644
--- a/plat/arm/css/common/css_pm.c
+++ b/plat/arm/css/common/css_pm.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015-2016, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2015-2017, ARM Limited and Contributors. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
@@ -75,6 +75,13 @@ const unsigned int arm_pm_idle_states[] = {
 CASSERT(PLAT_MAX_PWR_LVL >= ARM_PWR_LVL1,
 		assert_max_pwr_lvl_supported_mismatch);
 
+/*
+ * Ensure that the PLAT_MAX_PWR_LVL is not greater than CSS_SYSTEM_PWR_DMN_LVL
+ * assumed by the CSS layer.
+ */
+CASSERT(PLAT_MAX_PWR_LVL <= CSS_SYSTEM_PWR_DMN_LVL,
+		assert_max_pwr_lvl_higher_than_css_sys_lvl);
+
 /*******************************************************************************
  * Handler called when a power domain is about to be turned on. The
  * level and mpidr determine the affinity instance.
@@ -243,7 +250,7 @@ void css_get_sys_suspend_power_state(psci_power_state_t *req_state)
 	 * System Suspend is supported only if the system power domain node
 	 * is implemented.
 	 */
-	assert(PLAT_MAX_PWR_LVL >= ARM_PWR_LVL2);
+	assert(PLAT_MAX_PWR_LVL == CSS_SYSTEM_PWR_DMN_LVL);
 
 	for (i = ARM_PWR_LVL0; i <= PLAT_MAX_PWR_LVL; i++)
 		req_state->pwr_domain_state[i] = ARM_LOCAL_STATE_OFF;
@@ -257,6 +264,39 @@ int css_node_hw_state(u_register_t mpidr, unsigned int power_level)
 	return css_scp_get_power_state(mpidr, power_level);
 }
 
+/*
+ * The system power domain suspend is only supported only via
+ * PSCI SYSTEM_SUSPEND API. PSCI CPU_SUSPEND request to system power domain
+ * will be downgraded to the lower level.
+ */
+static int css_validate_power_state(unsigned int power_state,
+			    psci_power_state_t *req_state)
+{
+	int rc;
+	rc = arm_validate_power_state(power_state, req_state);
+
+	/*
+	 * Ensure that the system power domain level is never suspended
+	 * via PSCI CPU SUSPEND API. Currently system suspend is only
+	 * supported via PSCI SYSTEM SUSPEND API.
+	 */
+	req_state->pwr_domain_state[CSS_SYSTEM_PWR_DMN_LVL] = ARM_LOCAL_STATE_RUN;
+	return rc;
+}
+
+/*
+ * Custom `translate_power_state_by_mpidr` handler for CSS. Unlike in the
+ * `css_validate_power_state`, we do not downgrade the system power
+ * domain level request in `power_state` as it will be used to query the
+ * PSCI_STAT_COUNT/RESIDENCY at the system power domain level.
+ */
+static int css_translate_power_state_by_mpidr(u_register_t mpidr,
+		unsigned int power_state,
+		psci_power_state_t *output_state)
+{
+	return arm_validate_power_state(power_state, output_state);
+}
+
 /*******************************************************************************
  * Export the platform handlers via plat_arm_psci_pm_ops. The ARM Standard
  * platform will take care of registering the handlers with PSCI.
@@ -270,7 +310,9 @@ plat_psci_ops_t plat_arm_psci_pm_ops = {
 	.pwr_domain_suspend_finish	= css_pwr_domain_suspend_finish,
 	.system_off		= css_system_off,
 	.system_reset		= css_system_reset,
-	.validate_power_state	= arm_validate_power_state,
+	.validate_power_state	= css_validate_power_state,
 	.validate_ns_entrypoint = arm_validate_ns_entrypoint,
-	.get_node_hw_state	= css_node_hw_state
+	.translate_power_state_by_mpidr = css_translate_power_state_by_mpidr,
+	.get_node_hw_state	= css_node_hw_state,
+	.get_sys_suspend_power_state = css_get_sys_suspend_power_state
 };