diff options
| -rw-r--r-- | arch/arm/mm/Kconfig | 19 | ||||
| -rw-r--r-- | arch/arm/mm/cache-v6.S | 15 |
2 files changed, 31 insertions, 3 deletions
diff --git a/arch/arm/mm/Kconfig b/arch/arm/mm/Kconfig index 346ae14824a5..fc1b2fa59429 100644 --- a/arch/arm/mm/Kconfig +++ b/arch/arm/mm/Kconfig @@ -735,6 +735,25 @@ config NEEDS_SYSCALL_FOR_CMPXCHG Forget about fast user space cmpxchg support. It is just not possible. +config DMA_CACHE_RWFO + bool "Enable read/write for ownership DMA cache maintenance" + depends on CPU_V6 && SMP + default y + help + The Snoop Control Unit on ARM11MPCore does not detect the + cache maintenance operations and the dma_{map,unmap}_area() + functions may leave stale cache entries on other CPUs. By + enabling this option, Read or Write For Ownership in the ARMv6 + DMA cache maintenance functions is performed. These LDR/STR + instructions change the cache line state to shared or modified + so that the cache operation has the desired effect. + + Note that the workaround is only valid on processors that do + not perform speculative loads into the D-cache. For such + processors, if cache maintenance operations are not broadcast + in hardware, other workarounds are needed (e.g. cache + maintenance broadcasting in software via FIQ). + config OUTER_CACHE bool diff --git a/arch/arm/mm/cache-v6.S b/arch/arm/mm/cache-v6.S index 332b48c6d4ff..86aa689ef1aa 100644 --- a/arch/arm/mm/cache-v6.S +++ b/arch/arm/mm/cache-v6.S @@ -211,7 +211,7 @@ v6_dma_inv_range: mcrne p15, 0, r1, c7, c15, 1 @ clean & invalidate unified line #endif 1: -#ifdef CONFIG_SMP +#ifdef CONFIG_DMA_CACHE_RWFO ldr r2, [r0] @ read for ownership str r2, [r0] @ write for ownership #endif @@ -235,7 +235,7 @@ v6_dma_inv_range: v6_dma_clean_range: bic r0, r0, #D_CACHE_LINE_SIZE - 1 1: -#ifdef CONFIG_SMP +#ifdef CONFIG_DMA_CACHE_RWFO ldr r2, [r0] @ read for ownership #endif #ifdef HARVARD_CACHE @@ -258,7 +258,7 @@ v6_dma_clean_range: ENTRY(v6_dma_flush_range) bic r0, r0, #D_CACHE_LINE_SIZE - 1 1: -#ifdef CONFIG_SMP +#ifdef CONFIG_DMA_CACHE_RWFO ldr r2, [r0] @ read for ownership str r2, [r0] @ write for ownership #endif @@ -284,9 +284,13 @@ ENTRY(v6_dma_map_area) add r1, r1, r0 teq r2, #DMA_FROM_DEVICE beq v6_dma_inv_range +#ifndef CONFIG_DMA_CACHE_RWFO + b v6_dma_clean_range +#else teq r2, #DMA_TO_DEVICE beq v6_dma_clean_range b v6_dma_flush_range +#endif ENDPROC(v6_dma_map_area) /* @@ -296,6 +300,11 @@ ENDPROC(v6_dma_map_area) * - dir - DMA direction */ ENTRY(v6_dma_unmap_area) +#ifndef CONFIG_DMA_CACHE_RWFO + add r1, r1, r0 + teq r2, #DMA_TO_DEVICE + bne v6_dma_inv_range +#endif mov pc, lr ENDPROC(v6_dma_unmap_area) |