refactor(psci): absorb psci_power_down_wfi() into common code
The AArch64 and AArch32 variants are not that different so there is no
need for them to be in assembly. They should also not be called from
non-PSCI code as PSCI is smart enough to handle this after platform
hooks. So absorb the functions into common code.
This allows for a tiny bit of optimisation: there will be no branch
(that can be missed or non-cached) to a non-inlineable function. Then in
the terminal case we can call wfi() directly with the application of the
erratum before the loop. And finally in the wakeup case, we don't have
to explicitly clear the errata as that will happen automatically on the
second call of prepare_cpu_pwr_dwn().
The A510 erratum requires a tsb csync before the dsb+wfi combo to turn
the core off. We can do this a little bit earlier in the cpu hook and
relieve common code from the responsibility. EL3 is always a prohibited
region so the buffer will stay empty.
Change-Id: I5f950df3fb7b0736df4ce25a21f78b29896de215
Signed-off-by: Boyan Karatotev <boyan.karatotev@arm.com>
diff --git a/lib/psci/aarch32/psci_helpers.S b/lib/psci/aarch32/psci_helpers.S
index 4e1013c..929af8c 100644
--- a/lib/psci/aarch32/psci_helpers.S
+++ b/lib/psci/aarch32/psci_helpers.S
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 2016-2023, Arm Limited and Contributors. All rights reserved.
+ * Copyright (c) 2016-2025, Arm Limited and Contributors. All rights reserved.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
@@ -10,7 +10,6 @@
.globl psci_do_pwrdown_cache_maintenance
.globl psci_do_pwrup_cache_maintenance
- .globl psci_power_down_wfi
/* -----------------------------------------------------------------------
* void psci_do_pwrdown_cache_maintenance(unsigned int power level);
@@ -134,16 +133,3 @@
pop {r4, pc}
endfunc do_stack_maintenance
-
-/* -----------------------------------------------------------------------
- * This function is called to indicate to the power controller that it
- * is safe to power down this cpu. It should not exit the wfi and will
- * be released from reset upon power up.
- * -----------------------------------------------------------------------
- */
-func psci_power_down_wfi
- dsb sy // ensure write buffer empty
-1:
- wfi
- b 1b
-endfunc psci_power_down_wfi