1 files changed, 106 insertions, 0 deletions
diff --git a/arch/x86/kernel/pci-nommu.c b/arch/x86/kernel/pci-nommu.c
new file mode 100644
index 00000000..f9605068
--- /dev/null
+++ b/arch/x86/kernel/pci-nommu.c
@@ -0,0 +1,106 @@
+/* Fallback functions when the main IOMMU code is not compiled in. This
+   code is roughly equivalent to i386. */
+#include <linux/dma-mapping.h>
+#include <linux/scatterlist.h>
+#include <linux/string.h>
+#include <linux/init.h>
+#include <linux/gfp.h>
+#include <linux/pci.h>
+#include <linux/mm.h>
+
+#include <asm/processor.h>
+#include <asm/iommu.h>
+#include <asm/dma.h>
+
+static int
+check_addr(char *name, struct device *hwdev, dma_addr_t bus, size_t size)
+{
+	if (hwdev && !dma_capable(hwdev, bus, size)) {
+		if (*hwdev->dma_mask >= DMA_BIT_MASK(32))
+			printk(KERN_ERR
+			    "nommu_%s: overflow %Lx+%zu of device mask %Lx\n",
+				name, (long long)bus, size,
+				(long long)*hwdev->dma_mask);
+		return 0;
+	}
+	return 1;
+}
+
+static dma_addr_t nommu_map_page(struct device *dev, struct page *page,
+				 unsigned long offset, size_t size,
+				 enum dma_data_direction dir,
+				 struct dma_attrs *attrs)
+{
+	dma_addr_t bus = page_to_phys(page) + offset;
+	WARN_ON(size == 0);
+	if (!check_addr("map_single", dev, bus, size))
+		return DMA_ERROR_CODE;
+	flush_write_buffers();
+	return bus;
+}
+
+/* Map a set of buffers described by scatterlist in streaming
+ * mode for DMA.  This is the scatter-gather version of the
+ * above pci_map_single interface.  Here the scatter gather list
+ * elements are each tagged with the appropriate dma address
+ * and length.  They are obtained via sg_dma_{address,length}(SG).
+ *
+ * NOTE: An implementation may be able to use a smaller number of
+ *       DMA address/length pairs than there are SG table elements.
+ *       (for example via virtual mapping capabilities)
+ *       The routine returns the number of addr/length pairs actually
+ *       used, at most nents.
+ *
+ * Device ownership issues as mentioned above for pci_map_single are
+ * the same here.
+ */
+static int nommu_map_sg(struct device *hwdev, struct scatterlist *sg,
+			int nents, enum dma_data_direction dir,
+			struct dma_attrs *attrs)
+{
+	struct scatterlist *s;
+	int i;
+
+	WARN_ON(nents == 0 || sg[0].length == 0);
+
+	for_each_sg(sg, s, nents, i) {
+		BUG_ON(!sg_page(s));
+		s->dma_address = sg_phys(s);
+		if (!check_addr("map_sg", hwdev, s->dma_address, s->length))
+			return 0;
+		s->dma_length = s->length;
+	}
+	flush_write_buffers();
+	return nents;
+}
+
+static void nommu_free_coherent(struct device *dev, size_t size, void *vaddr,
+				dma_addr_t dma_addr, struct dma_attrs *attrs)
+{
+	free_pages((unsigned long)vaddr, get_order(size));
+}
+
+static void nommu_sync_single_for_device(struct device *dev,
+			dma_addr_t addr, size_t size,
+			enum dma_data_direction dir)
+{
+	flush_write_buffers();
+}
+
+
+static void nommu_sync_sg_for_device(struct device *dev,
+			struct scatterlist *sg, int nelems,
+			enum dma_data_direction dir)
+{
+	flush_write_buffers();
+}
+
+struct dma_map_ops nommu_dma_ops = {
+	.alloc			= dma_generic_alloc_coherent,
+	.free			= nommu_free_coherent,
+	.map_sg			= nommu_map_sg,
+	.map_page		= nommu_map_page,
+	.sync_single_for_device = nommu_sync_single_for_device,
+	.sync_sg_for_device	= nommu_sync_sg_for_device,
+	.is_phys		= 1,
+};