dma-direct: reject too small dma masks
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
diff --git a/lib/dma-direct.c b/lib/dma-direct.c
index 784a68d..40b1f92 100644
--- a/lib/dma-direct.c
+++ b/lib/dma-direct.c
@@ -122,6 +122,24 @@
return nents;
}
+int dma_direct_supported(struct device *dev, u64 mask)
+{
+#ifdef CONFIG_ZONE_DMA
+ if (mask < DMA_BIT_MASK(ARCH_ZONE_DMA_BITS))
+ return 0;
+#else
+ /*
+ * Because 32-bit DMA masks are so common we expect every architecture
+ * to be able to satisfy them - either by not supporting more physical
+ * memory, or by providing a ZONE_DMA32. If neither is the case, the
+ * architecture needs to use an IOMMU instead of the direct mapping.
+ */
+ if (mask < DMA_BIT_MASK(32))
+ return 0;
+#endif
+ return 1;
+}
+
static int dma_direct_mapping_error(struct device *dev, dma_addr_t dma_addr)
{
return dma_addr == DIRECT_MAPPING_ERROR;
@@ -132,6 +150,7 @@
.free = dma_direct_free,
.map_page = dma_direct_map_page,
.map_sg = dma_direct_map_sg,
+ .dma_supported = dma_direct_supported,
.mapping_error = dma_direct_mapping_error,
};
EXPORT_SYMBOL(dma_direct_ops);