[PATCH 1/3] dma: Use dma-mapping for cache ops and sync after write

[Andrew Davis]

The DMA'd memory area needs cleaned and invalidated after the DMA
write so that any stale cache lines do not mask new data.

Signed-off-by: Andrew Davis <afd at ti.com>
---
 drivers/dma/dma-uclass.c | 17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/drivers/dma/dma-uclass.c b/drivers/dma/dma-uclass.c
index 012609bb53..70f06f1f09 100644
--- a/drivers/dma/dma-uclass.c
+++ b/drivers/dma/dma-uclass.c
@@ -19,6 +19,7 @@
 #include <asm/cache.h>
 #include <dm/read.h>
 #include <dma-uclass.h>
+#include <linux/dma-mapping.h>
 #include <dt-structs.h>
 #include <errno.h>
 
@@ -235,6 +236,8 @@ int dma_memcpy(void *dst, void *src, size_t len)
 {
 	struct udevice *dev;
 	const struct dma_ops *ops;
+	dma_addr_t destination;
+	dma_addr_t source;
 	int ret;
 
 	ret = dma_get_device(DMA_SUPPORTS_MEM_TO_MEM, &dev);
@@ -245,11 +248,17 @@ int dma_memcpy(void *dst, void *src, size_t len)
 	if (!ops->transfer)
 		return -ENOSYS;
 
-	/* Invalidate the area, so no writeback into the RAM races with DMA */
-	invalidate_dcache_range((unsigned long)dst, (unsigned long)dst +
-				roundup(len, ARCH_DMA_MINALIGN));
+	/* Clean the areas, so no writeback into the RAM races with DMA */
+	destination = dma_map_single(dst, len, DMA_FROM_DEVICE);
+	source = dma_map_single(src, len, DMA_TO_DEVICE);
 
-	return ops->transfer(dev, DMA_MEM_TO_MEM, dst, src, len);
+	ret = ops->transfer(dev, DMA_MEM_TO_MEM, dst, src, len);
+
+	/* Clean+Invalidate the areas after, so we can see DMA'd data */
+	dma_unmap_single(destination, len, DMA_FROM_DEVICE);
+	dma_unmap_single(source, len, DMA_TO_DEVICE);
+
+	return ret;
 }
 
 UCLASS_DRIVER(dma) = {
-- 
2.37.3