diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
index 6f51b30..2171f86 100644
--- a/drivers/gpu/drm/ttm/ttm_bo.c
+++ b/drivers/gpu/drm/ttm/ttm_bo.c
@@ -632,6 +632,7 @@ static int ttm_bo_evict(struct ttm_buffer_object *bo, bool interruptible,
 
 	evict_mem = bo->mem;
 	evict_mem.mm_node = NULL;
+	evict_mem.bus.io_reserved = false;
 
 	placement.fpfn = 0;
 	placement.lpfn = 0;
@@ -1005,6 +1006,7 @@ int ttm_bo_move_buffer(struct ttm_buffer_object *bo,
 	mem.num_pages = bo->num_pages;
 	mem.size = mem.num_pages << PAGE_SHIFT;
 	mem.page_alignment = bo->mem.page_alignment;
+	mem.bus.io_reserved = false;
 	/*
 	 * Determine where to move the buffer.
 	 */
@@ -1160,6 +1162,7 @@ int ttm_bo_init(struct ttm_bo_device *bdev,
 	bo->mem.num_pages = bo->num_pages;
 	bo->mem.mm_node = NULL;
 	bo->mem.page_alignment = page_alignment;
+	bo->mem.bus.io_reserved = false;
 	bo->buffer_start = buffer_start & PAGE_MASK;
 	bo->priv_flags = 0;
 	bo->mem.placement = (TTM_PL_FLAG_SYSTEM | TTM_PL_FLAG_CACHED);
@@ -1574,7 +1577,7 @@ int ttm_bo_pci_offset(struct ttm_bo_device *bdev,
 	if (ttm_mem_reg_is_pci(bdev, mem)) {
 		*bus_offset = mem->mm_node->start << PAGE_SHIFT;
 		*bus_size = mem->num_pages << PAGE_SHIFT;
-		*bus_base = man->io_offset;
+		*bus_base = man->io_offset + (uintptr_t)man->io_addr;
 	}
 
 	return 0;
@@ -1588,8 +1591,8 @@ void ttm_bo_unmap_virtual(struct ttm_buffer_object *bo)
 
 	if (!bdev->dev_mapping)
 		return;
-
 	unmap_mapping_range(bdev->dev_mapping, offset, holelen, 1);
+	ttm_mem_io_free(bdev, &bo->mem);
 }
 EXPORT_SYMBOL(ttm_bo_unmap_virtual);
 
diff --git a/drivers/gpu/drm/ttm/ttm_bo_util.c b/drivers/gpu/drm/ttm/ttm_bo_util.c
index 865b2a8..8493f39 100644
--- a/drivers/gpu/drm/ttm/ttm_bo_util.c
+++ b/drivers/gpu/drm/ttm/ttm_bo_util.c
@@ -81,30 +81,61 @@ int ttm_bo_move_ttm(struct ttm_buffer_object *bo,
 }
 EXPORT_SYMBOL(ttm_bo_move_ttm);
 
+int ttm_mem_io_reserve(struct ttm_bo_device *bdev, struct ttm_mem_reg *mem)
+{
+	struct ttm_mem_type_manager *man = &bdev->man[mem->mem_type];
+	int ret;
+
+	if (bdev->driver->io_mem_reserve) {
+		if (!mem->bus.io_reserved) {
+			mem->bus.io_reserved = true;
+			ret = bdev->driver->io_mem_reserve(bdev, mem);
+			if (unlikely(ret != 0))
+				return ret;
+		}
+	} else {
+		ret = ttm_bo_pci_offset(bdev, mem, &mem->bus.base, &mem->bus.offset, &mem->bus.size);
+		if (unlikely(ret != 0))
+			return ret;
+		mem->bus.addr = man->io_addr;
+		mem->bus.is_iomem = (mem->bus.size > 0) ? 1 : 0;
+	}
+	return 0;
+}
+
+void ttm_mem_io_free(struct ttm_bo_device *bdev, struct ttm_mem_reg *mem)
+{
+	if (bdev->driver->io_mem_reserve) {
+		if (mem->bus.io_reserved) {
+			mem->bus.io_reserved = false;
+			bdev->driver->io_mem_free(bdev, mem);
+		}
+	}
+}
+
 int ttm_mem_reg_ioremap(struct ttm_bo_device *bdev, struct ttm_mem_reg *mem,
 			void **virtual)
 {
 	struct ttm_mem_type_manager *man = &bdev->man[mem->mem_type];
-	unsigned long bus_offset;
-	unsigned long bus_size;
-	unsigned long bus_base;
 	int ret;
 	void *addr;
 
 	*virtual = NULL;
-	ret = ttm_bo_pci_offset(bdev, mem, &bus_base, &bus_offset, &bus_size);
-	if (ret || bus_size == 0)
+	ret = ttm_mem_io_reserve(bdev, mem);
+	if (ret)
 		return ret;
 
-	if (!(man->flags & TTM_MEMTYPE_FLAG_NEEDS_IOREMAP))
-		addr = (void *)(((u8 *) man->io_addr) + bus_offset);
-	else {
+	if (!(man->flags & TTM_MEMTYPE_FLAG_NEEDS_IOREMAP)) {
+		addr = mem->bus.addr;
+	} else {
 		if (mem->placement & TTM_PL_FLAG_WC)
-			addr = ioremap_wc(bus_base + bus_offset, bus_size);
+			addr = ioremap_wc(mem->bus.base + mem->bus.offset, mem->bus.size);
 		else
-			addr = ioremap_nocache(bus_base + bus_offset, bus_size);
-		if (!addr)
+			addr = ioremap_nocache(mem->bus.base + mem->bus.offset, mem->bus.size);
+		if (!addr) {
+			ttm_mem_io_free(bdev, mem);
 			return -ENOMEM;
+		}
 	}
 	*virtual = addr;
 	return 0;
@@ -119,6 +150,7 @@ void ttm_mem_reg_iounmap(struct ttm_bo_device *bdev, struct ttm_mem_reg *mem,
 
 	if (virtual && (man->flags & TTM_MEMTYPE_FLAG_NEEDS_IOREMAP))
 		iounmap(virtual);
+	ttm_mem_io_free(bdev, mem);
 }
 
 static int ttm_copy_io_page(void *dst, void *src, unsigned long page)
@@ -370,9 +402,8 @@ pgprot_t ttm_io_prot(uint32_t caching_flags, pgprot_t tmp)
 EXPORT_SYMBOL(ttm_io_prot);
 
 static int ttm_bo_ioremap(struct ttm_buffer_object *bo,
-			  unsigned long bus_base,
-			  unsigned long bus_offset,
-			  unsigned long bus_size,
+			  unsigned long offset,
+			  unsigned long size,
 			  struct ttm_bo_kmap_obj *map)
 {
 	struct ttm_bo_device *bdev = bo->bdev;
@@ -381,15 +412,15 @@ static int ttm_bo_ioremap(struct ttm_buffer_object *bo,
 
 	if (!(man->flags & TTM_MEMTYPE_FLAG_NEEDS_IOREMAP)) {
 		map->bo_kmap_type = ttm_bo_map_premapped;
-		map->virtual = (void *)(((u8 *) man->io_addr) + bus_offset);
+		map->virtual = (void *)(((u8 *) bo->mem.bus.addr) + offset);
 	} else {
 		map->bo_kmap_type = ttm_bo_map_iomap;
 		if (mem->placement & TTM_PL_FLAG_WC)
-			map->virtual = ioremap_wc(bus_base + bus_offset,
-						  bus_size);
+			map->virtual = ioremap_wc(bo->mem.bus.base + bo->mem.bus.offset + offset,
+						  size);
 		else
-			map->virtual = ioremap_nocache(bus_base + bus_offset,
-						       bus_size);
+			map->virtual = ioremap_nocache(bo->mem.bus.base + bo->mem.bus.offset + offset,
+						       size);
 	}
 	return (!map->virtual) ? -ENOMEM : 0;
 }
@@ -442,13 +473,12 @@ int ttm_bo_kmap(struct ttm_buffer_object *bo,
 		unsigned long start_page, unsigned long num_pages,
 		struct ttm_bo_kmap_obj *map)
 {
+	unsigned long offset, size;
 	int ret;
-	unsigned long bus_base;
-	unsigned long bus_offset;
-	unsigned long bus_size;
 
 	BUG_ON(!list_empty(&bo->swap));
 	map->virtual = NULL;
+	map->bo = bo;
 	if (num_pages > bo->num_pages)
 		return -EINVAL;
 	if (start_page > bo->num_pages)
@@ -457,16 +487,15 @@ int ttm_bo_kmap(struct ttm_buffer_object *bo,
 	if (num_pages > 1 && !DRM_SUSER(DRM_CURPROC))
 		return -EPERM;
 #endif
-	ret = ttm_bo_pci_offset(bo->bdev, &bo->mem, &bus_base,
-				&bus_offset, &bus_size);
+	ret = ttm_mem_io_reserve(bo->bdev, &bo->mem);
 	if (ret)
 		return ret;
-	if (bus_size == 0) {
+	if (!bo->mem.bus.is_iomem) {
 		return ttm_bo_kmap_ttm(bo, start_page, num_pages, map);
 	} else {
-		bus_offset += start_page << PAGE_SHIFT;
-		bus_size = num_pages << PAGE_SHIFT;
-		return ttm_bo_ioremap(bo, bus_base, bus_offset, bus_size, map);
+		offset = start_page << PAGE_SHIFT;
+		size = num_pages << PAGE_SHIFT;
+		return ttm_bo_ioremap(bo, offset, size, map);
 	}
 }
 EXPORT_SYMBOL(ttm_bo_kmap);
@@ -478,6 +507,7 @@ void ttm_bo_kunmap(struct ttm_bo_kmap_obj *map)
 	switch (map->bo_kmap_type) {
 	case ttm_bo_map_iomap:
 		iounmap(map->virtual);
+		ttm_mem_io_free(map->bo->bdev, &map->bo->mem);
 		break;
 	case ttm_bo_map_vmap:
 		vunmap(map->virtual);
@@ -495,35 +525,6 @@ void ttm_bo_kunmap(struct ttm_bo_kmap_obj *map)
 }
 EXPORT_SYMBOL(ttm_bo_kunmap);
 
-int ttm_bo_pfn_prot(struct ttm_buffer_object *bo,
-		    unsigned long dst_offset,
-		    unsigned long *pfn, pgprot_t *prot)
-{
-	struct ttm_mem_reg *mem = &bo->mem;
-	struct ttm_bo_device *bdev = bo->bdev;
-	unsigned long bus_offset;
-	unsigned long bus_size;
-	unsigned long bus_base;
-	int ret;
-	ret = ttm_bo_pci_offset(bdev, mem, &bus_base, &bus_offset,
-			&bus_size);
-	if (ret)
-		return -EINVAL;
-	if (bus_size != 0)
-		*pfn = (bus_base + bus_offset + dst_offset) >> PAGE_SHIFT;
-	else
-		if (!bo->ttm)
-			return -EINVAL;
-		else
-			*pfn = page_to_pfn(ttm_tt_get_page(bo->ttm,
-							   dst_offset >>
-							   PAGE_SHIFT));
-	*prot = (mem->placement & TTM_PL_FLAG_CACHED) ?
-		PAGE_KERNEL : ttm_io_prot(mem->placement, PAGE_KERNEL);
-
-	return 0;
-}
-
 int ttm_bo_move_accel_cleanup(struct ttm_buffer_object *bo,
 			      void *sync_obj,
 			      void *sync_obj_arg,
diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c b/drivers/gpu/drm/ttm/ttm_bo_vm.c
index 668dbe8..fe6cb77 100644
--- a/drivers/gpu/drm/ttm/ttm_bo_vm.c
+++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c
@@ -74,9 +74,6 @@ static int ttm_bo_vm_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 	struct ttm_buffer_object *bo = (struct ttm_buffer_object *)
 	    vma->vm_private_data;
 	struct ttm_bo_device *bdev = bo->bdev;
-	unsigned long bus_base;
-	unsigned long bus_offset;
-	unsigned long bus_size;
 	unsigned long page_offset;
 	unsigned long page_last;
 	unsigned long pfn;
@@ -84,7 +81,6 @@ static int ttm_bo_vm_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 	struct page *page;
 	int ret;
 	int i;
-	bool is_iomem;
 	unsigned long address = (unsigned long)vmf->virtual_address;
 	int retval = VM_FAULT_NOPAGE;
 
@@ -101,8 +97,21 @@ static int ttm_bo_vm_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 		return VM_FAULT_NOPAGE;
 	}
 
-	if (bdev->driver->fault_reserve_notify)
-		bdev->driver->fault_reserve_notify(bo);
+	if (bdev->driver->fault_reserve_notify) {
+		ret = bdev->driver->fault_reserve_notify(bo);
+		switch (ret) {
+		case 0:
+			break;
+		case -EBUSY:
+			set_need_resched();
+		case -ERESTARTSYS:
+			retval = VM_FAULT_NOPAGE;
+			goto out_unlock;
+		default:
+			retval = VM_FAULT_SIGBUS;
+			goto out_unlock;
+		}
+	}
 
 	/*
 	 * Wait for buffer data in transit, due to a pipelined
@@ -122,15 +131,12 @@ static int ttm_bo_vm_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 		spin_unlock(&bo->lock);
 
 
-	ret = ttm_bo_pci_offset(bdev, &bo->mem, &bus_base, &bus_offset,
-				&bus_size);
-	if (unlikely(ret != 0)) {
+	ret = ttm_mem_io_reserve(bdev, &bo->mem);
+	if (ret) {
 		retval = VM_FAULT_SIGBUS;
 		goto out_unlock;
 	}
 
-	is_iomem = (bus_size != 0);
-
 	page_offset = ((address - vma->vm_start) >> PAGE_SHIFT) +
 	    bo->vm_node->start - vma->vm_pgoff;
 	page_last = ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) +
@@ -154,8 +160,7 @@ static int ttm_bo_vm_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 	 * vma->vm_page_prot when the object changes caching policy, with
 	 * the correct locks held.
 	 */
-
-	if (is_iomem) {
+	if (bo->mem.bus.is_iomem) {
 		vma->vm_page_prot = ttm_io_prot(bo->mem.placement,
 						vma->vm_page_prot);
 	} else {
@@ -171,10 +176,8 @@ static int ttm_bo_vm_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 	 */
 
 	for (i = 0; i < TTM_BO_VM_NUM_PREFAULT; ++i) {
-
-		if (is_iomem)
-			pfn = ((bus_base + bus_offset) >> PAGE_SHIFT) +
-			    page_offset;
+		if (bo->mem.bus.is_iomem)
+			pfn = ((bo->mem.bus.base + bo->mem.bus.offset) >> PAGE_SHIFT) + page_offset;
 		else {
 			page = ttm_tt_get_page(ttm, page_offset);
 			if (unlikely(!page && i == 0)) {
@@ -198,7 +201,6 @@ static int ttm_bo_vm_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 			retval =
 			    (ret == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS;
 			goto out_unlock;
-
 		}
 
 		address += PAGE_SIZE;
@@ -221,8 +223,7 @@ static void ttm_bo_vm_open(struct vm_area_struct *vma)
 
 static void ttm_bo_vm_close(struct vm_area_struct *vma)
 {
-	struct ttm_buffer_object *bo =
-	    (struct ttm_buffer_object *)vma->vm_private_data;
+	struct ttm_buffer_object *bo = (struct ttm_buffer_object *)vma->vm_private_data;
 
 	ttm_bo_unref(&bo);
 	vma->vm_private_data = NULL;
diff --git a/include/drm/ttm/ttm_bo_api.h b/include/drm/ttm/ttm_bo_api.h
index 8c8005e..3e273e0 100644
--- a/include/drm/ttm/ttm_bo_api.h
+++ b/include/drm/ttm/ttm_bo_api.h
@@ -66,6 +66,26 @@ struct ttm_placement {
 	const uint32_t	*busy_placement;
 };
 
+/**
+ * struct ttm_bus_placement
+ *
+ * @addr:		mapped virtual address
+ * @base:		bus base address
+ * @is_iomem:		is this io memory ?
+ * @size:		size in byte
+ * @offset:		offset from the base address
+ *
+ * Structure indicating the bus placement of an object.
+ */
+struct ttm_bus_placement {
+	void		*addr;
+	unsigned long	base;
+	unsigned long	size;
+	unsigned long	offset;
+	bool		is_iomem;
+	bool		io_reserved;
+};
+
 
 /**
  * struct ttm_mem_reg
@@ -75,6 +95,7 @@ struct ttm_placement {
  * @num_pages: Actual size of memory region in pages.
  * @page_alignment: Page alignment.
  * @placement: Placement flags.
+ * @bus: Placement on io bus accessible to the CPU
  *
  * Structure indicating the placement and space resources used by a
  * buffer object.
@@ -87,6 +108,7 @@ struct ttm_mem_reg {
 	uint32_t page_alignment;
 	uint32_t mem_type;
 	uint32_t placement;
+	struct ttm_bus_placement bus;
 };
 
 /**
@@ -274,6 +296,7 @@ struct ttm_bo_kmap_obj {
 		ttm_bo_map_kmap         = 3,
 		ttm_bo_map_premapped    = 4 | TTM_BO_MAP_IOMEM_MASK,
 	} bo_kmap_type;
+	struct ttm_buffer_object *bo;
 };
 
 /**
diff --git a/include/drm/ttm/ttm_bo_driver.h b/include/drm/ttm/ttm_bo_driver.h
index 69f70e4..da39865 100644
--- a/include/drm/ttm/ttm_bo_driver.h
+++ b/include/drm/ttm/ttm_bo_driver.h
@@ -352,12 +352,21 @@ struct ttm_bo_driver {
 			    struct ttm_mem_reg *new_mem);
 	/* notify the driver we are taking a fault on this BO
 	 * and have reserved it */
-	void (*fault_reserve_notify)(struct ttm_buffer_object *bo);
+	int (*fault_reserve_notify)(struct ttm_buffer_object *bo);
 
 	/**
 	 * notify the driver that we're about to swap out this bo
 	 */
 	void (*swap_notify) (struct ttm_buffer_object *bo);
+
+	/**
+	 * Driver callback on when mapping io memory (for bo_move_memcpy
+	 * for instance). TTM will take care to call io_mem_free whenever
+	 * the mapping is not use anymore. io_mem_reserve & io_mem_free
+	 * are balanced.
+	 */
+	int (*io_mem_reserve)(struct ttm_bo_device *bdev, struct ttm_mem_reg *mem);
+	void (*io_mem_free)(struct ttm_bo_device *bdev, struct ttm_mem_reg *mem);
 };
 
 /**
@@ -685,6 +694,11 @@ extern int ttm_bo_pci_offset(struct ttm_bo_device *bdev,
 			     unsigned long *bus_offset,
 			     unsigned long *bus_size);
 
+extern int ttm_mem_io_reserve(struct ttm_bo_device *bdev,
+				struct ttm_mem_reg *mem);
+extern void ttm_mem_io_free(struct ttm_bo_device *bdev,
+				struct ttm_mem_reg *mem);
+
 extern void ttm_bo_global_release(struct ttm_global_reference *ref);
 extern int ttm_bo_global_init(struct ttm_global_reference *ref);
 
