patch-2.4.20 linux-2.4.20/arch/x86_64/kernel/pci-dma.c

• Lines: 75
• Date: Thu Nov 28 15:53:12 2002
• Orig file: linux-2.4.19/arch/x86_64/kernel/pci-dma.c
• Orig date: Wed Dec 31 16:00:00 1969

diff -urN linux-2.4.19/arch/x86_64/kernel/pci-dma.c linux-2.4.20/arch/x86_64/kernel/pci-dma.c
@@ -0,0 +1,74 @@
+/*
+ * Dynamic DMA mapping support. Common code
+ */
+
+#include <linux/types.h>
+#include <linux/mm.h>
+#include <linux/string.h>
+#include <linux/pci.h>
+#include <asm/io.h>
+
+dma_addr_t bad_dma_address = -1UL; 
+
+/* Map a set of buffers described by scatterlist in streaming
+ * mode for DMA.  This is the scather-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.
+ */
+int pci_map_sg(struct pci_dev *hwdev, struct scatterlist *sg,
+			     int nents, int direction)
+{
+	int i;
+
+	BUG_ON(direction == PCI_DMA_NONE);
+ 
+ 	/*
+ 	 * temporary 2.4 hack
+ 	 */
+ 	for (i = 0; i < nents; i++ ) {
+		struct scatterlist *s = &sg[i];
+ 		if (s->address) {
+			BUG_ON(s->page || s->offset); 
+ 			s->dma_address = pci_map_single(hwdev, s->address, s->length, 
+							direction); 
+ 		} else if (s->page) { 
+			s->dma_address = pci_map_page(hwdev, s->page, s->offset,
+						      s->length, direction); 
+		} else
+			BUG(); 
+
+		if (unlikely(s->dma_address == bad_dma_address))
+			goto error; 
+ 	}
+	return nents;
+
+ error: 
+	pci_unmap_sg(hwdev, sg, i, direction); 
+	return 0; 
+}
+
+/* Unmap a set of streaming mode DMA translations.
+ * Again, cpu read rules concerning calls here are the same as for
+ * pci_unmap_single() above.
+ */
+void pci_unmap_sg(struct pci_dev *dev, struct scatterlist *sg, 
+				  int nents, int dir)
+{
+	int i;
+	for (i = 0; i < nents; i++) { 
+		struct scatterlist *s = &sg[i];
+		BUG_ON(s->address == NULL && s->page == NULL); 
+		BUG_ON(s->dma_address == 0); 
+		pci_unmap_single(dev, s->dma_address, s->length, dir); 
+	} 
+}