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https://github.com/ARM-software/arm-trusted-firmware.git
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695a48b5b4
A processing element should never return from a wfi, however, due to a hardware bug, certain CPUs may wake up because of an external event. This patch tightens the behaviour of the common power down sequence, it ensures the routine never returns by entering a wfi loop at its end. It aligns with the behaviour of the platform implementations. Change-Id: I36d8b0c64eccb71035bf164b4cd658d66ed7beb4 Signed-off-by: Harrison Mutai <harrison.mutai@arm.com>
149 lines
4.3 KiB
ArmAsm
149 lines
4.3 KiB
ArmAsm
/*
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* Copyright (c) 2016-2023, ARM Limited and Contributors. All rights reserved.
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*
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* SPDX-License-Identifier: BSD-3-Clause
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*/
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#include <asm_macros.S>
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#include <lib/psci/psci.h>
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#include <platform_def.h>
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.globl psci_do_pwrdown_cache_maintenance
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.globl psci_do_pwrup_cache_maintenance
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.globl psci_power_down_wfi
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/* -----------------------------------------------------------------------
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* void psci_do_pwrdown_cache_maintenance(unsigned int power level);
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*
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* This function performs cache maintenance for the specified power
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* level. The levels of cache affected are determined by the power
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* level which is passed as the argument i.e. level 0 results
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* in a flush of the L1 cache. Both the L1 and L2 caches are flushed
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* for a higher power level.
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*
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* Additionally, this function also ensures that stack memory is correctly
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* flushed out to avoid coherency issues due to a change in its memory
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* attributes after the data cache is disabled.
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* -----------------------------------------------------------------------
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*/
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func psci_do_pwrdown_cache_maintenance
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push {r4, lr}
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/* ----------------------------------------------
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* Turn OFF cache and do stack maintenance
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* prior to cpu operations . This sequence is
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* different from AArch64 because in AArch32 the
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* assembler routines for cpu operations utilize
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* the stack whereas in AArch64 it doesn't.
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* ----------------------------------------------
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*/
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mov r4, r0
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bl do_stack_maintenance
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/* ---------------------------------------------
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* Invoke CPU-specifc power down operations for
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* the appropriate level
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* ---------------------------------------------
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*/
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mov r0, r4
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pop {r4, lr}
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b prepare_cpu_pwr_dwn
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endfunc psci_do_pwrdown_cache_maintenance
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/* -----------------------------------------------------------------------
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* void psci_do_pwrup_cache_maintenance(void);
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*
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* This function performs cache maintenance after this cpu is powered up.
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* Currently, this involves managing the used stack memory before turning
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* on the data cache.
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* -----------------------------------------------------------------------
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*/
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func psci_do_pwrup_cache_maintenance
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/* r12 is pushed to meet the 8 byte stack alignment requirement */
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push {r12, lr}
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/* ---------------------------------------------
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* Ensure any inflight stack writes have made it
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* to main memory.
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* ---------------------------------------------
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*/
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dmb st
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/* ---------------------------------------------
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* Calculate and store the size of the used
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* stack memory in r1. Calculate and store the
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* stack base address in r0.
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* ---------------------------------------------
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*/
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bl plat_get_my_stack
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mov r1, sp
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sub r1, r0, r1
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mov r0, sp
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bl inv_dcache_range
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/* ---------------------------------------------
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* Enable the data cache.
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* ---------------------------------------------
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*/
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ldcopr r0, SCTLR
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orr r0, r0, #SCTLR_C_BIT
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stcopr r0, SCTLR
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isb
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pop {r12, pc}
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endfunc psci_do_pwrup_cache_maintenance
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/* ---------------------------------------------
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* void do_stack_maintenance(void)
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* Do stack maintenance by flushing the used
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* stack to the main memory and invalidating the
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* remainder.
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* ---------------------------------------------
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*/
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func do_stack_maintenance
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push {r4, lr}
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bl plat_get_my_stack
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/* Turn off the D-cache */
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ldcopr r1, SCTLR
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bic r1, #SCTLR_C_BIT
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stcopr r1, SCTLR
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isb
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/* ---------------------------------------------
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* Calculate and store the size of the used
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* stack memory in r1.
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* ---------------------------------------------
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*/
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mov r4, r0
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mov r1, sp
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sub r1, r0, r1
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mov r0, sp
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bl flush_dcache_range
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/* ---------------------------------------------
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* Calculate and store the size of the unused
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* stack memory in r1. Calculate and store the
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* stack base address in r0.
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* ---------------------------------------------
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*/
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sub r0, r4, #PLATFORM_STACK_SIZE
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sub r1, sp, r0
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bl inv_dcache_range
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pop {r4, pc}
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endfunc do_stack_maintenance
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/* -----------------------------------------------------------------------
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* This function is called to indicate to the power controller that it
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* is safe to power down this cpu. It should not exit the wfi and will
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* be released from reset upon power up.
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* -----------------------------------------------------------------------
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*/
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func psci_power_down_wfi
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dsb sy // ensure write buffer empty
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1:
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wfi
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b 1b
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endfunc psci_power_down_wfi
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