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arm: mach-k3: Clean non-coherent lines out of L3 cache

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When switching on or off the ARM caches some care must be taken to ensure
existing cache line allocations are not left in an inconsistent state.
An example of this is when cache lines are considered non-shared by
and L3 controller even though the lines are shared. To prevent these
and other issues all cache lines should be cleared before enabling
or disabling a coherent master's cache. ARM cores and many L3 controllers
provide a way to efficiently clean out all cache lines to allow for
this, unfortunately there is no such easy way to do this on current K3
MSMC based systems.

We could explicitly clean out every valid external address tracked by
MSMC (all of DRAM), or we could attempt to identify only the set of
addresses accessed by a given boot stage and flush only those
specifically. This patch attempts the latter. We start with cleaning the
SPL load address. More addresses can be added here later as they are
identified.

Note that we perform a flush operation for both the flush and invalidate
operations, this is not a typo. We do this to avoid the situation that
some ARM cores will promote an invalidate to a clean+invalidate, but only
emit the invalidation operation externally, leading to a loss of data.

Signed-off-by: Andrew F. Davis <afd@ti.com>
Tested-by: Faiz Abbas <faiz_abbas@ti.com>
This commit is contained in:
Andrew F. Davis 2020-07-15 17:02:36 -04:00 committed by Lokesh Vutla
parent e1c3668594
commit 864e285739
2 changed files with 25 additions and 0 deletions
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1
arch/arm/mach-k3/Makefile
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@ -8,6 +8,7 @@ obj-$(CONFIG_SOC_K3_J721E) += j721e_init.o
obj-$(CONFIG_ARM64) += arm64-mmu.o
obj-$(CONFIG_CPU_V7R) += r5_mpu.o lowlevel_init.o
obj-$(CONFIG_TI_SECURE_DEVICE) += security.o
obj-$(CONFIG_ARM64) += cache.o
ifeq ($(CONFIG_SPL_BUILD),y)
obj-$(CONFIG_K3_LOAD_SYSFW) += sysfw-loader.o
endif

24
arch/arm/mach-k3/cache.S Normal file
View file

@ -0,0 +1,24 @@
/* SPDX-License-Identifier: GPL-2.0 */
/*
* Copyright (C) 2020 Texas Instruments Incorporated - http://www.ti.com/
* Andrew F. Davis <afd@ti.com>
*/
#include <config.h>
#include <linux/linkage.h>
#if defined(CONFIG_SPL_BUILD)
ENTRY(__asm_invalidate_l3_dcache)
/* Invalidate SPL address range */
mov x0, #CONFIG_SPL_TEXT_BASE
add x1, x0, #CONFIG_SPL_MAX_SIZE
b __asm_flush_dcache_range
ENDPROC(__asm_invalidate_l3_dcache)
ENTRY(__asm_flush_l3_dcache)
/* Flush SPL address range */
mov x0, #CONFIG_SPL_TEXT_BASE
add x1, x0, #CONFIG_SPL_MAX_SIZE
b __asm_flush_dcache_range
ENDPROC(__asm_flush_l3_dcache)
#endif