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ARM: 6111/1: Implement read/write for ownership in the ARMv6 DMA cache ops 

The Snoop Control Unit on the ARM11MPCore hardware does not detect the
cache operations and the dma_cache_maint*() functions may leave stale
cache entries on other CPUs. The solution implemented in this patch
performs a Read or Write For Ownership in the ARMv6 DMA cache
maintenance functions. These LDR/STR instructions change the cache line
state to shared or exclusive so that the cache maintenance operation has
the desired effect.

Tested-by: George G. Davis <gdavis@mvista.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Catalin Marinas 2010-05-07 16:26:24 +01:00 committed by Russell King
parent b5a07faade
commit f4d6477f7f
1 changed files with 13 additions and 4 deletions
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17
arch/arm/mm/cache-v6.S
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@ -211,6 +211,9 @@ v6_dma_inv_range:
mcrne p15, 0, r1, c7, c15, 1 @ clean & invalidate unified line
#endif
1:
#ifdef CONFIG_SMP
str r0, [r0] @ write for ownership
#endif
#ifdef HARVARD_CACHE
mcr p15, 0, r0, c7, c6, 1 @ invalidate D line
#else
@ -231,6 +234,9 @@ v6_dma_inv_range:
v6_dma_clean_range:
bic r0, r0, #D_CACHE_LINE_SIZE - 1
1:
#ifdef CONFIG_SMP
ldr r2, [r0] @ read for ownership
#endif
#ifdef HARVARD_CACHE
mcr p15, 0, r0, c7, c10, 1 @ clean D line
#else
@ -251,6 +257,10 @@ v6_dma_clean_range:
ENTRY(v6_dma_flush_range)
bic r0, r0, #D_CACHE_LINE_SIZE - 1
1:
#ifdef CONFIG_SMP
ldr r2, [r0] @ read for ownership
str r2, [r0] @ write for ownership
#endif
#ifdef HARVARD_CACHE
mcr p15, 0, r0, c7, c14, 1 @ clean & invalidate D line
#else
@ -273,7 +283,9 @@ ENTRY(v6_dma_map_area)
add r1, r1, r0
teq r2, #DMA_FROM_DEVICE
beq v6_dma_inv_range
b v6_dma_clean_range
teq r2, #DMA_TO_DEVICE
beq v6_dma_clean_range
b v6_dma_flush_range
ENDPROC(v6_dma_map_area)
/*
@ -283,9 +295,6 @@ ENDPROC(v6_dma_map_area)
* - dir - DMA direction
*/
ENTRY(v6_dma_unmap_area)
add r1, r1, r0
teq r2, #DMA_TO_DEVICE
bne v6_dma_inv_range
mov pc, lr
ENDPROC(v6_dma_unmap_area)