ARM: 6188/1: Add a config option for the ARM11MPCore DMA cache maintenance workaround
Commit f4d6477f introduced a workaround for the lack of hardware
broadcasting of the cache maintenance operations on ARM11MPCore.
However, the workaround is only valid on CPUs that do not do speculative
loads into the D-cache.
This patch adds a Kconfig option with the corresponding help to make the
above clear. When the DMA_CACHE_RWFO option is disabled, the kernel
behaviour is that prior to the f4d6477f commit. This also allows ARMv6
UP processors with speculative loads to work correctly.
For other processors, a different workaround may be needed.
Cc: Ronen Shitrit <rshitrit@marvell.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/arch/arm/mm/cache-v6.S b/arch/arm/mm/cache-v6.S
index 332b48c..86aa689 100644
--- a/arch/arm/mm/cache-v6.S
+++ b/arch/arm/mm/cache-v6.S
@@ -211,7 +211,7 @@
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_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 @@
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 @@
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 @@
* - 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)