1 files changed, 69 insertions, 2 deletions

diff --git a/arch/powerpc/kernel/dma-iommu.c b/arch/powerpc/kernel/dma-iommu.c
index a1c744194018..111249fd619d 100644
--- a/arch/powerpc/kernel/dma-iommu.c
+++ b/arch/powerpc/kernel/dma-iommu.c
@@ -10,6 +10,63 @@
 #include <linux/pci.h>
 #include <asm/iommu.h>
 
+#ifdef CONFIG_ARCH_HAS_DMA_MAP_DIRECT
+#define can_map_direct(dev, addr) \
+	((dev)->bus_dma_limit >= phys_to_dma((dev), (addr)))
+
+bool arch_dma_map_page_direct(struct device *dev, phys_addr_t addr)
+{
+	if (likely(!dev->bus_dma_limit))
+		return false;
+
+	return can_map_direct(dev, addr);
+}
+
+#define is_direct_handle(dev, h) ((h) >= (dev)->archdata.dma_offset)
+
+bool arch_dma_unmap_page_direct(struct device *dev, dma_addr_t dma_handle)
+{
+	if (likely(!dev->bus_dma_limit))
+		return false;
+
+	return is_direct_handle(dev, dma_handle);
+}
+
+bool arch_dma_map_sg_direct(struct device *dev, struct scatterlist *sg,
+			    int nents)
+{
+	struct scatterlist *s;
+	int i;
+
+	if (likely(!dev->bus_dma_limit))
+		return false;
+
+	for_each_sg(sg, s, nents, i) {
+		if (!can_map_direct(dev, sg_phys(s) + s->offset + s->length))
+			return false;
+	}
+
+	return true;
+}
+
+bool arch_dma_unmap_sg_direct(struct device *dev, struct scatterlist *sg,
+			      int nents)
+{
+	struct scatterlist *s;
+	int i;
+
+	if (likely(!dev->bus_dma_limit))
+		return false;
+
+	for_each_sg(sg, s, nents, i) {
+		if (!is_direct_handle(dev, s->dma_address + s->length))
+			return false;
+	}
+
+	return true;
+}
+#endif /* CONFIG_ARCH_HAS_DMA_MAP_DIRECT */
+
 /*
  * Generic iommu implementation
  */
@@ -90,8 +147,18 @@ int dma_iommu_dma_supported(struct device *dev, u64 mask)
 	struct iommu_table *tbl = get_iommu_table_base(dev);
 
 	if (dev_is_pci(dev) && dma_iommu_bypass_supported(dev, mask)) {
-		dev->dma_ops_bypass = true;
-		dev_dbg(dev, "iommu: 64-bit OK, using fixed ops\n");
+		/*
+		 * dma_iommu_bypass_supported() sets dma_max when there is
+		 * 1:1 mapping but it is somehow limited.
+		 * ibm,pmemory is one example.
+		 */
+		dev->dma_ops_bypass = dev->bus_dma_limit == 0;
+		if (!dev->dma_ops_bypass)
+			dev_warn(dev,
+				 "iommu: 64-bit OK but direct DMA is limited by %llx\n",
+				 dev->bus_dma_limit);
+		else
+			dev_dbg(dev, "iommu: 64-bit OK, using fixed ops\n");
 		return 1;
 	}