ARC: I/O and DMA Mappings

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

arch/arc/plat-arcfpga/include/plat/dma_addr.h

@@ -0,0 +1,45 @@
+/*
+ * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * vineetg: Feb 2009
+ *  -For AA4 board, kernel to DMA address APIs
+ */
+
+/*
+ * kernel addresses are 0x800_000 based, while Bus addr are 0 based
+ */
+
+#ifndef __PLAT_DMA_ADDR_H
+#define __PLAT_DMA_ADDR_H
+
+#include <linux/device.h>
+
+static inline unsigned long plat_dma_addr_to_kernel(struct device *dev,
+						    dma_addr_t dma_addr)
+{
+	return dma_addr + PAGE_OFFSET;
+}
+
+static inline dma_addr_t plat_kernel_addr_to_dma(struct device *dev, void *ptr)
+{
+	unsigned long addr = (unsigned long)ptr;
+	/*
+	 * To Catch buggy drivers which can call DMA map API with kernel vaddr
+	 * i.e. for buffers alloc via vmalloc or ioremap which are not
+	 * gaurnateed to be PHY contiguous and hence unfit for DMA anyways.
+	 * On ARC kernel virtual address is 0x7000_0000 to 0x7FFF_FFFF, so
+	 * ideally we want to check this range here, but our implementation is
+	 * better as it checks for even worse user virtual address as well.
+	 */
+	if (likely(addr >= PAGE_OFFSET))
+		return addr - PAGE_OFFSET;
+
+	BUG();
+	return addr;
+}
+
+#endif