Tegra: Enable irq as wake-up event for cpu_standby
As per ARM ARM D1.17.2, any physical IRQ interrupt received by the PE
will be treated as a wake-up event, if SCR_EL3.IRQ is set to '1',
irrespective of the value of the PSTATE.I bit value.
This patch programs the SCR_EL3.IRQ bit before entering CPU standby
state, to allow an IRQ to wake the PE. On waking up, the previous
SCR_EL3 value is restored.
Change-Id: Ie81cf3a7668f5ac35f4bf2ecc461b91b9b60650c
Signed-off-by: Vignesh Radhakrishnan <vigneshr@nvidia.com>
diff --git a/plat/nvidia/tegra/common/tegra_pm.c b/plat/nvidia/tegra/common/tegra_pm.c
index fbc0f11..4275cf3 100644
--- a/plat/nvidia/tegra/common/tegra_pm.c
+++ b/plat/nvidia/tegra/common/tegra_pm.c
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 2015-2017, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2015-2018, ARM Limited and Contributors. All rights reserved.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
@@ -146,18 +146,37 @@
******************************************************************************/
void tegra_cpu_standby(plat_local_state_t cpu_state)
{
+ u_register_t saved_scr_el3;
+
(void)cpu_state;
/* Tegra SoC specific handler */
if (tegra_soc_cpu_standby(cpu_state) != PSCI_E_SUCCESS)
ERROR("%s failed\n", __func__);
+ saved_scr_el3 = read_scr_el3();
+
+ /*
+ * As per ARM ARM D1.17.2, any physical IRQ interrupt received by the
+ * PE will be treated as a wake-up event, if SCR_EL3.IRQ is set to '1',
+ * irrespective of the value of the PSTATE.I bit value.
+ */
+ write_scr_el3(saved_scr_el3 | SCR_IRQ_BIT);
+
/*
* Enter standby state
- * dsb is good practice before using wfi to enter low power states
+ *
+ * dsb & isb is good practice before using wfi to enter low power states
*/
dsb();
+ isb();
wfi();
+
+ /*
+ * Restore saved scr_el3 that has IRQ bit cleared as we don't want EL3
+ * handling any further interrupts
+ */
+ write_scr_el3(saved_scr_el3);
}
/*******************************************************************************