powerpc/dma: Add optional platform override of dma_set_mask()

Some platforms may want to override dma_set_mask() to take into
account some specific "features" such as the availability of
a direct-map window in addition to an iommu.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 18 insertions, 0 deletions

diff --git a/arch/powerpc/kernel/dma.c b/arch/powerpc/kernel/dma.c
index 84d6367ec003..f368c075c90b 100644
--- a/arch/powerpc/kernel/dma.c
+++ b/arch/powerpc/kernel/dma.c
@@ -12,6 +12,7 @@
 #include <linux/memblock.h>
 #include <asm/bug.h>
 #include <asm/abs_addr.h>
+#include <asm/machdep.h>
 
 /*
  * Generic direct DMA implementation
@@ -154,6 +155,23 @@ EXPORT_SYMBOL(dma_direct_ops);
 
 #define PREALLOC_DMA_DEBUG_ENTRIES (1 << 16)
 
+int dma_set_mask(struct device *dev, u64 dma_mask)
+{
+        struct dma_map_ops *dma_ops = get_dma_ops(dev);
+
+        if (ppc_md.dma_set_mask)
+                return ppc_md.dma_set_mask(dev, dma_mask);
+        if (unlikely(dma_ops == NULL))
+                return -EIO;
+        if (dma_ops->set_dma_mask != NULL)
+                return dma_ops->set_dma_mask(dev, dma_mask);
+        if (!dev->dma_mask || !dma_supported(dev, dma_mask))
+                return -EIO;
+        *dev->dma_mask = dma_mask;
+        return 0;
+}
+EXPORT_SYMBOL(dma_set_mask);
+
 static int __init dma_init(void)
 {
        dma_debug_init(PREALLOC_DMA_DEBUG_ENTRIES);