Hexagon: use correct translations for DMA mappings

With physical offsets, pa<->va translations aren't just based
on PAGE_OFFSET anymore.

Signed-off-by: Richard Kuo <rkuo@codeaurora.org>

arch/hexagon/include/asm/page.h

@@ -140,6 +140,11 @@ static inline void clear_page(void *page)
  */
 #define page_to_phys(page)      (page_to_pfn(page) << PAGE_SHIFT)
 
+#define virt_to_pfn(kaddr)      (__pa(kaddr) >> PAGE_SHIFT)
+#define pfn_to_virt(pfn)        __va((pfn) << PAGE_SHIFT)
+
+#define page_to_virt(page)	__va(page_to_phys(page))
+
 /*
  * For port to Hexagon Virtual Machine, MAYBE we check for attempts
  * to reference reserved HVM space, but in any case, the VM will be

arch/hexagon/kernel/dma.c

@@ -1,7 +1,7 @@
 /*
  * DMA implementation for Hexagon
  *
- * Copyright (c) 2010-2011, The Linux Foundation. All rights reserved.
+ * Copyright (c) 2010-2012, The Linux Foundation. All rights reserved.
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 and
@@ -23,12 +23,18 @@
 #include <linux/genalloc.h>
 #include <asm/dma-mapping.h>
 #include <linux/module.h>
+#include <asm/page.h>
 
 struct dma_map_ops *dma_ops;
 EXPORT_SYMBOL(dma_ops);
 
 int bad_dma_address;  /*  globals are automatically initialized to zero  */
 
+static inline void *dma_addr_to_virt(dma_addr_t dma_addr)
+{
+	return phys_to_virt((unsigned long) dma_addr);
+}
+
 int dma_supported(struct device *dev, u64 mask)
 {
 	if (mask == DMA_BIT_MASK(32))
@@ -60,6 +66,12 @@ static void *hexagon_dma_alloc_coherent(struct device *dev, size_t size,
 {
 	void *ret;
 
+	/*
+	 * Our max_low_pfn should have been backed off by 16MB in
+	 * mm/init.c to create DMA coherent space.  Use that as the VA
+	 * for the pool.
+	 */
+
 	if (coherent_pool == NULL) {
 		coherent_pool = gen_pool_create(PAGE_SHIFT, -1);
 
@@ -67,7 +79,7 @@ static void *hexagon_dma_alloc_coherent(struct device *dev, size_t size,
 			panic("Can't create %s() memory pool!", __func__);
 		else
 			gen_pool_add(coherent_pool,
-				(PAGE_OFFSET + (max_low_pfn << PAGE_SHIFT)),
+				pfn_to_virt(max_low_pfn),
 				hexagon_coherent_pool_size, -1);
 	}
 
@@ -75,7 +87,7 @@ static void *hexagon_dma_alloc_coherent(struct device *dev, size_t size,
 
 	if (ret) {
 		memset(ret, 0, size);
-		*dma_addr = (dma_addr_t) (ret - PAGE_OFFSET);
+		*dma_addr = (dma_addr_t) virt_to_phys(ret);
 	} else
 		*dma_addr = ~0;
 
@@ -118,8 +130,8 @@ static int hexagon_map_sg(struct device *hwdev, struct scatterlist *sg,
 
 		s->dma_length = s->length;
 
-		flush_dcache_range(PAGE_OFFSET + s->dma_address,
-				   PAGE_OFFSET + s->dma_address + s->length);
+		flush_dcache_range(dma_addr_to_virt(s->dma_address),
+				   dma_addr_to_virt(s->dma_address + s->length));
 	}
 
 	return nents;
@@ -149,11 +161,6 @@ static inline void dma_sync(void *addr, size_t size,
 	}
 }
 
-static inline void *dma_addr_to_virt(dma_addr_t dma_addr)
-{
-	return phys_to_virt((unsigned long) dma_addr);
-}
-
 /**
  * hexagon_map_page() - maps an address for device DMA
  * @dev:	pointer to DMA device