Initial import

1 files changed, 861 insertions, 0 deletions

diff --git a/drivers/gpu/drm/drm_mm.c b/drivers/gpu/drm/drm_mm.c
new file mode 100644
index 000000000..113452628
--- /dev/null
+++ b/drivers/gpu/drm/drm_mm.c
@@ -0,0 +1,861 @@
+/**************************************************************************
+ *
+ * Copyright 2006 Tungsten Graphics, Inc., Bismarck, ND., USA.
+ * All Rights Reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sub license, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the
+ * next paragraph) shall be included in all copies or substantial portions
+ * of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
+ * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
+ * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+ * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
+ * USE OR OTHER DEALINGS IN THE SOFTWARE.
+ *
+ *
+ **************************************************************************/
+
+/*
+ * Generic simple memory manager implementation. Intended to be used as a base
+ * class implementation for more advanced memory managers.
+ *
+ * Note that the algorithm used is quite simple and there might be substantial
+ * performance gains if a smarter free list is implemented. Currently it is just an
+ * unordered stack of free regions. This could easily be improved if an RB-tree
+ * is used instead. At least if we expect heavy fragmentation.
+ *
+ * Aligned allocations can also see improvement.
+ *
+ * Authors:
+ * Thomas Hellström <thomas-at-tungstengraphics-dot-com>
+ */
+
+#include <drm/drmP.h>
+#include <drm/drm_mm.h>
+#include <linux/slab.h>
+#include <linux/seq_file.h>
+#include <linux/export.h>
+
+/**
+ * DOC: Overview
+ *
+ * drm_mm provides a simple range allocator. The drivers are free to use the
+ * resource allocator from the linux core if it suits them, the upside of drm_mm
+ * is that it's in the DRM core. Which means that it's easier to extend for
+ * some of the crazier special purpose needs of gpus.
+ *
+ * The main data struct is &drm_mm, allocations are tracked in &drm_mm_node.
+ * Drivers are free to embed either of them into their own suitable
+ * datastructures. drm_mm itself will not do any allocations of its own, so if
+ * drivers choose not to embed nodes they need to still allocate them
+ * themselves.
+ *
+ * The range allocator also supports reservation of preallocated blocks. This is
+ * useful for taking over initial mode setting configurations from the firmware,
+ * where an object needs to be created which exactly matches the firmware's
+ * scanout target. As long as the range is still free it can be inserted anytime
+ * after the allocator is initialized, which helps with avoiding looped
+ * depencies in the driver load sequence.
+ *
+ * drm_mm maintains a stack of most recently freed holes, which of all
+ * simplistic datastructures seems to be a fairly decent approach to clustering
+ * allocations and avoiding too much fragmentation. This means free space
+ * searches are O(num_holes). Given that all the fancy features drm_mm supports
+ * something better would be fairly complex and since gfx thrashing is a fairly
+ * steep cliff not a real concern. Removing a node again is O(1).
+ *
+ * drm_mm supports a few features: Alignment and range restrictions can be
+ * supplied. Further more every &drm_mm_node has a color value (which is just an
+ * opaqua unsigned long) which in conjunction with a driver callback can be used
+ * to implement sophisticated placement restrictions. The i915 DRM driver uses
+ * this to implement guard pages between incompatible caching domains in the
+ * graphics TT.
+ *
+ * Two behaviors are supported for searching and allocating: bottom-up and top-down.
+ * The default is bottom-up. Top-down allocation can be used if the memory area
+ * has different restrictions, or just to reduce fragmentation.
+ *
+ * Finally iteration helpers to walk all nodes and all holes are provided as are
+ * some basic allocator dumpers for debugging.
+ */
+
+static struct drm_mm_node *drm_mm_search_free_generic(const struct drm_mm *mm,
+						u64 size,
+						unsigned alignment,
+						unsigned long color,
+						enum drm_mm_search_flags flags);
+static struct drm_mm_node *drm_mm_search_free_in_range_generic(const struct drm_mm *mm,
+						u64 size,
+						unsigned alignment,
+						unsigned long color,
+						u64 start,
+						u64 end,
+						enum drm_mm_search_flags flags);
+
+static void drm_mm_insert_helper(struct drm_mm_node *hole_node,
+				 struct drm_mm_node *node,
+				 u64 size, unsigned alignment,
+				 unsigned long color,
+				 enum drm_mm_allocator_flags flags)
+{
+	struct drm_mm *mm = hole_node->mm;
+	u64 hole_start = drm_mm_hole_node_start(hole_node);
+	u64 hole_end = drm_mm_hole_node_end(hole_node);
+	u64 adj_start = hole_start;
+	u64 adj_end = hole_end;
+
+	BUG_ON(node->allocated);
+
+	if (mm->color_adjust)
+		mm->color_adjust(hole_node, color, &adj_start, &adj_end);
+
+	if (flags & DRM_MM_CREATE_TOP)
+		adj_start = adj_end - size;
+
+	if (alignment) {
+		u64 tmp = adj_start;
+		unsigned rem;
+
+		rem = do_div(tmp, alignment);
+		if (rem) {
+			if (flags & DRM_MM_CREATE_TOP)
+				adj_start -= rem;
+			else
+				adj_start += alignment - rem;
+		}
+	}
+
+	BUG_ON(adj_start < hole_start);
+	BUG_ON(adj_end > hole_end);
+
+	if (adj_start == hole_start) {
+		hole_node->hole_follows = 0;
+		list_del(&hole_node->hole_stack);
+	}
+
+	node->start = adj_start;
+	node->size = size;
+	node->mm = mm;
+	node->color = color;
+	node->allocated = 1;
+
+	INIT_LIST_HEAD(&node->hole_stack);
+	list_add(&node->node_list, &hole_node->node_list);
+
+	BUG_ON(node->start + node->size > adj_end);
+
+	node->hole_follows = 0;
+	if (__drm_mm_hole_node_start(node) < hole_end) {
+		list_add(&node->hole_stack, &mm->hole_stack);
+		node->hole_follows = 1;
+	}
+}
+
+/**
+ * drm_mm_reserve_node - insert an pre-initialized node
+ * @mm: drm_mm allocator to insert @node into
+ * @node: drm_mm_node to insert
+ *
+ * This functions inserts an already set-up drm_mm_node into the allocator,
+ * meaning that start, size and color must be set by the caller. This is useful
+ * to initialize the allocator with preallocated objects which must be set-up
+ * before the range allocator can be set-up, e.g. when taking over a firmware
+ * framebuffer.
+ *
+ * Returns:
+ * 0 on success, -ENOSPC if there's no hole where @node is.
+ */
+int drm_mm_reserve_node(struct drm_mm *mm, struct drm_mm_node *node)
+{
+	struct drm_mm_node *hole;
+	u64 end = node->start + node->size;
+	u64 hole_start;
+	u64 hole_end;
+
+	BUG_ON(node == NULL);
+
+	/* Find the relevant hole to add our node to */
+	drm_mm_for_each_hole(hole, mm, hole_start, hole_end) {
+		if (hole_start > node->start || hole_end < end)
+			continue;
+
+		node->mm = mm;
+		node->allocated = 1;
+
+		INIT_LIST_HEAD(&node->hole_stack);
+		list_add(&node->node_list, &hole->node_list);
+
+		if (node->start == hole_start) {
+			hole->hole_follows = 0;
+			list_del_init(&hole->hole_stack);
+		}
+
+		node->hole_follows = 0;
+		if (end != hole_end) {
+			list_add(&node->hole_stack, &mm->hole_stack);
+			node->hole_follows = 1;
+		}
+
+		return 0;
+	}
+
+	return -ENOSPC;
+}
+EXPORT_SYMBOL(drm_mm_reserve_node);
+
+/**
+ * drm_mm_insert_node_generic - search for space and insert @node
+ * @mm: drm_mm to allocate from
+ * @node: preallocate node to insert
+ * @size: size of the allocation
+ * @alignment: alignment of the allocation
+ * @color: opaque tag value to use for this node
+ * @sflags: flags to fine-tune the allocation search
+ * @aflags: flags to fine-tune the allocation behavior
+ *
+ * The preallocated node must be cleared to 0.
+ *
+ * Returns:
+ * 0 on success, -ENOSPC if there's no suitable hole.
+ */
+int drm_mm_insert_node_generic(struct drm_mm *mm, struct drm_mm_node *node,
+			       u64 size, unsigned alignment,
+			       unsigned long color,
+			       enum drm_mm_search_flags sflags,
+			       enum drm_mm_allocator_flags aflags)
+{
+	struct drm_mm_node *hole_node;
+
+	hole_node = drm_mm_search_free_generic(mm, size, alignment,
+					       color, sflags);
+	if (!hole_node)
+		return -ENOSPC;
+
+	drm_mm_insert_helper(hole_node, node, size, alignment, color, aflags);
+	return 0;
+}
+EXPORT_SYMBOL(drm_mm_insert_node_generic);
+
+static void drm_mm_insert_helper_range(struct drm_mm_node *hole_node,
+				       struct drm_mm_node *node,
+				       u64 size, unsigned alignment,
+				       unsigned long color,
+				       u64 start, u64 end,
+				       enum drm_mm_allocator_flags flags)
+{
+	struct drm_mm *mm = hole_node->mm;
+	u64 hole_start = drm_mm_hole_node_start(hole_node);
+	u64 hole_end = drm_mm_hole_node_end(hole_node);
+	u64 adj_start = hole_start;
+	u64 adj_end = hole_end;
+
+	BUG_ON(!hole_node->hole_follows || node->allocated);
+
+	if (adj_start < start)
+		adj_start = start;
+	if (adj_end > end)
+		adj_end = end;
+
+	if (flags & DRM_MM_CREATE_TOP)
+		adj_start = adj_end - size;
+
+	if (mm->color_adjust)
+		mm->color_adjust(hole_node, color, &adj_start, &adj_end);
+
+	if (alignment) {
+		u64 tmp = adj_start;
+		unsigned rem;
+
+		rem = do_div(tmp, alignment);
+		if (rem) {
+			if (flags & DRM_MM_CREATE_TOP)
+				adj_start -= rem;
+			else
+				adj_start += alignment - rem;
+		}
+	}
+
+	if (adj_start == hole_start) {
+		hole_node->hole_follows = 0;
+		list_del(&hole_node->hole_stack);
+	}
+
+	node->start = adj_start;
+	node->size = size;
+	node->mm = mm;
+	node->color = color;
+	node->allocated = 1;
+
+	INIT_LIST_HEAD(&node->hole_stack);
+	list_add(&node->node_list, &hole_node->node_list);
+
+	BUG_ON(node->start < start);
+	BUG_ON(node->start < adj_start);
+	BUG_ON(node->start + node->size > adj_end);
+	BUG_ON(node->start + node->size > end);
+
+	node->hole_follows = 0;
+	if (__drm_mm_hole_node_start(node) < hole_end) {
+		list_add(&node->hole_stack, &mm->hole_stack);
+		node->hole_follows = 1;
+	}
+}
+
+/**
+ * drm_mm_insert_node_in_range_generic - ranged search for space and insert @node
+ * @mm: drm_mm to allocate from
+ * @node: preallocate node to insert
+ * @size: size of the allocation
+ * @alignment: alignment of the allocation
+ * @color: opaque tag value to use for this node
+ * @start: start of the allowed range for this node
+ * @end: end of the allowed range for this node
+ * @sflags: flags to fine-tune the allocation search
+ * @aflags: flags to fine-tune the allocation behavior
+ *
+ * The preallocated node must be cleared to 0.
+ *
+ * Returns:
+ * 0 on success, -ENOSPC if there's no suitable hole.
+ */
+int drm_mm_insert_node_in_range_generic(struct drm_mm *mm, struct drm_mm_node *node,
+					u64 size, unsigned alignment,
+					unsigned long color,
+					u64 start, u64 end,
+					enum drm_mm_search_flags sflags,
+					enum drm_mm_allocator_flags aflags)
+{
+	struct drm_mm_node *hole_node;
+
+	hole_node = drm_mm_search_free_in_range_generic(mm,
+							size, alignment, color,
+							start, end, sflags);
+	if (!hole_node)
+		return -ENOSPC;
+
+	drm_mm_insert_helper_range(hole_node, node,
+				   size, alignment, color,
+				   start, end, aflags);
+	return 0;
+}
+EXPORT_SYMBOL(drm_mm_insert_node_in_range_generic);
+
+/**
+ * drm_mm_remove_node - Remove a memory node from the allocator.
+ * @node: drm_mm_node to remove
+ *
+ * This just removes a node from its drm_mm allocator. The node does not need to
+ * be cleared again before it can be re-inserted into this or any other drm_mm
+ * allocator. It is a bug to call this function on a un-allocated node.
+ */
+void drm_mm_remove_node(struct drm_mm_node *node)
+{
+	struct drm_mm *mm = node->mm;
+	struct drm_mm_node *prev_node;
+
+	if (WARN_ON(!node->allocated))
+		return;
+
+	BUG_ON(node->scanned_block || node->scanned_prev_free
+				   || node->scanned_next_free);
+
+	prev_node =
+	    list_entry(node->node_list.prev, struct drm_mm_node, node_list);
+
+	if (node->hole_follows) {
+		BUG_ON(__drm_mm_hole_node_start(node) ==
+		       __drm_mm_hole_node_end(node));
+		list_del(&node->hole_stack);
+	} else
+		BUG_ON(__drm_mm_hole_node_start(node) !=
+		       __drm_mm_hole_node_end(node));
+
+
+	if (!prev_node->hole_follows) {
+		prev_node->hole_follows = 1;
+		list_add(&prev_node->hole_stack, &mm->hole_stack);
+	} else
+		list_move(&prev_node->hole_stack, &mm->hole_stack);
+
+	list_del(&node->node_list);
+	node->allocated = 0;
+}
+EXPORT_SYMBOL(drm_mm_remove_node);
+
+static int check_free_hole(u64 start, u64 end, u64 size, unsigned alignment)
+{
+	if (end - start < size)
+		return 0;
+
+	if (alignment) {
+		u64 tmp = start;
+		unsigned rem;
+
+		rem = do_div(tmp, alignment);
+		if (rem)
+			start += alignment - rem;
+	}
+
+	return end >= start + size;
+}
+
+static struct drm_mm_node *drm_mm_search_free_generic(const struct drm_mm *mm,
+						      u64 size,
+						      unsigned alignment,
+						      unsigned long color,
+						      enum drm_mm_search_flags flags)
+{
+	struct drm_mm_node *entry;
+	struct drm_mm_node *best;
+	u64 adj_start;
+	u64 adj_end;
+	u64 best_size;
+
+	BUG_ON(mm->scanned_blocks);
+
+	best = NULL;
+	best_size = ~0UL;
+
+	__drm_mm_for_each_hole(entry, mm, adj_start, adj_end,
+			       flags & DRM_MM_SEARCH_BELOW) {
+		u64 hole_size = adj_end - adj_start;
+
+		if (mm->color_adjust) {
+			mm->color_adjust(entry, color, &adj_start, &adj_end);
+			if (adj_end <= adj_start)
+				continue;
+		}
+
+		if (!check_free_hole(adj_start, adj_end, size, alignment))
+			continue;
+
+		if (!(flags & DRM_MM_SEARCH_BEST))
+			return entry;
+
+		if (hole_size < best_size) {
+			best = entry;
+			best_size = hole_size;
+		}
+	}
+
+	return best;
+}
+
+static struct drm_mm_node *drm_mm_search_free_in_range_generic(const struct drm_mm *mm,
+							u64 size,
+							unsigned alignment,
+							unsigned long color,
+							u64 start,
+							u64 end,
+							enum drm_mm_search_flags flags)
+{
+	struct drm_mm_node *entry;
+	struct drm_mm_node *best;
+	u64 adj_start;
+	u64 adj_end;
+	u64 best_size;
+
+	BUG_ON(mm->scanned_blocks);
+
+	best = NULL;
+	best_size = ~0UL;
+
+	__drm_mm_for_each_hole(entry, mm, adj_start, adj_end,
+			       flags & DRM_MM_SEARCH_BELOW) {
+		u64 hole_size = adj_end - adj_start;
+
+		if (adj_start < start)
+			adj_start = start;
+		if (adj_end > end)
+			adj_end = end;
+
+		if (mm->color_adjust) {
+			mm->color_adjust(entry, color, &adj_start, &adj_end);
+			if (adj_end <= adj_start)
+				continue;
+		}
+
+		if (!check_free_hole(adj_start, adj_end, size, alignment))
+			continue;
+
+		if (!(flags & DRM_MM_SEARCH_BEST))
+			return entry;
+
+		if (hole_size < best_size) {
+			best = entry;
+			best_size = hole_size;
+		}
+	}
+
+	return best;
+}
+
+/**
+ * drm_mm_replace_node - move an allocation from @old to @new
+ * @old: drm_mm_node to remove from the allocator
+ * @new: drm_mm_node which should inherit @old's allocation
+ *
+ * This is useful for when drivers embed the drm_mm_node structure and hence
+ * can't move allocations by reassigning pointers. It's a combination of remove
+ * and insert with the guarantee that the allocation start will match.
+ */
+void drm_mm_replace_node(struct drm_mm_node *old, struct drm_mm_node *new)
+{
+	list_replace(&old->node_list, &new->node_list);
+	list_replace(&old->hole_stack, &new->hole_stack);
+	new->hole_follows = old->hole_follows;
+	new->mm = old->mm;
+	new->start = old->start;
+	new->size = old->size;
+	new->color = old->color;
+
+	old->allocated = 0;
+	new->allocated = 1;
+}
+EXPORT_SYMBOL(drm_mm_replace_node);
+
+/**
+ * DOC: lru scan roaster
+ *
+ * Very often GPUs need to have continuous allocations for a given object. When
+ * evicting objects to make space for a new one it is therefore not most
+ * efficient when we simply start to select all objects from the tail of an LRU
+ * until there's a suitable hole: Especially for big objects or nodes that
+ * otherwise have special allocation constraints there's a good chance we evict
+ * lots of (smaller) objects unecessarily.
+ *
+ * The DRM range allocator supports this use-case through the scanning
+ * interfaces. First a scan operation needs to be initialized with
+ * drm_mm_init_scan() or drm_mm_init_scan_with_range(). The the driver adds
+ * objects to the roaster (probably by walking an LRU list, but this can be
+ * freely implemented) until a suitable hole is found or there's no further
+ * evitable object.
+ *
+ * The the driver must walk through all objects again in exactly the reverse
+ * order to restore the allocator state. Note that while the allocator is used
+ * in the scan mode no other operation is allowed.
+ *
+ * Finally the driver evicts all objects selected in the scan. Adding and
+ * removing an object is O(1), and since freeing a node is also O(1) the overall
+ * complexity is O(scanned_objects). So like the free stack which needs to be
+ * walked before a scan operation even begins this is linear in the number of
+ * objects. It doesn't seem to hurt badly.
+ */
+
+/**
+ * drm_mm_init_scan - initialize lru scanning
+ * @mm: drm_mm to scan
+ * @size: size of the allocation
+ * @alignment: alignment of the allocation
+ * @color: opaque tag value to use for the allocation
+ *
+ * This simply sets up the scanning routines with the parameters for the desired
+ * hole. Note that there's no need to specify allocation flags, since they only
+ * change the place a node is allocated from within a suitable hole.
+ *
+ * Warning:
+ * As long as the scan list is non-empty, no other operations than
+ * adding/removing nodes to/from the scan list are allowed.
+ */
+void drm_mm_init_scan(struct drm_mm *mm,
+		      u64 size,
+		      unsigned alignment,
+		      unsigned long color)
+{
+	mm->scan_color = color;
+	mm->scan_alignment = alignment;
+	mm->scan_size = size;
+	mm->scanned_blocks = 0;
+	mm->scan_hit_start = 0;
+	mm->scan_hit_end = 0;
+	mm->scan_check_range = 0;
+	mm->prev_scanned_node = NULL;
+}
+EXPORT_SYMBOL(drm_mm_init_scan);
+
+/**
+ * drm_mm_init_scan - initialize range-restricted lru scanning
+ * @mm: drm_mm to scan
+ * @size: size of the allocation
+ * @alignment: alignment of the allocation
+ * @color: opaque tag value to use for the allocation
+ * @start: start of the allowed range for the allocation
+ * @end: end of the allowed range for the allocation
+ *
+ * This simply sets up the scanning routines with the parameters for the desired
+ * hole. Note that there's no need to specify allocation flags, since they only
+ * change the place a node is allocated from within a suitable hole.
+ *
+ * Warning:
+ * As long as the scan list is non-empty, no other operations than
+ * adding/removing nodes to/from the scan list are allowed.
+ */
+void drm_mm_init_scan_with_range(struct drm_mm *mm,
+				 u64 size,
+				 unsigned alignment,
+				 unsigned long color,
+				 u64 start,
+				 u64 end)
+{
+	mm->scan_color = color;
+	mm->scan_alignment = alignment;
+	mm->scan_size = size;
+	mm->scanned_blocks = 0;
+	mm->scan_hit_start = 0;
+	mm->scan_hit_end = 0;
+	mm->scan_start = start;
+	mm->scan_end = end;
+	mm->scan_check_range = 1;
+	mm->prev_scanned_node = NULL;
+}
+EXPORT_SYMBOL(drm_mm_init_scan_with_range);
+
+/**
+ * drm_mm_scan_add_block - add a node to the scan list
+ * @node: drm_mm_node to add
+ *
+ * Add a node to the scan list that might be freed to make space for the desired
+ * hole.
+ *
+ * Returns:
+ * True if a hole has been found, false otherwise.
+ */
+bool drm_mm_scan_add_block(struct drm_mm_node *node)
+{
+	struct drm_mm *mm = node->mm;
+	struct drm_mm_node *prev_node;
+	u64 hole_start, hole_end;
+	u64 adj_start, adj_end;
+
+	mm->scanned_blocks++;
+
+	BUG_ON(node->scanned_block);
+	node->scanned_block = 1;
+
+	prev_node = list_entry(node->node_list.prev, struct drm_mm_node,
+			       node_list);
+
+	node->scanned_preceeds_hole = prev_node->hole_follows;
+	prev_node->hole_follows = 1;
+	list_del(&node->node_list);
+	node->node_list.prev = &prev_node->node_list;
+	node->node_list.next = &mm->prev_scanned_node->node_list;
+	mm->prev_scanned_node = node;
+
+	adj_start = hole_start = drm_mm_hole_node_start(prev_node);
+	adj_end = hole_end = drm_mm_hole_node_end(prev_node);
+
+	if (mm->scan_check_range) {
+		if (adj_start < mm->scan_start)
+			adj_start = mm->scan_start;
+		if (adj_end > mm->scan_end)
+			adj_end = mm->scan_end;
+	}
+
+	if (mm->color_adjust)
+		mm->color_adjust(prev_node, mm->scan_color,
+				 &adj_start, &adj_end);
+
+	if (check_free_hole(adj_start, adj_end,
+			    mm->scan_size, mm->scan_alignment)) {
+		mm->scan_hit_start = hole_start;
+		mm->scan_hit_end = hole_end;
+		return true;
+	}
+
+	return false;
+}
+EXPORT_SYMBOL(drm_mm_scan_add_block);
+
+/**
+ * drm_mm_scan_remove_block - remove a node from the scan list
+ * @node: drm_mm_node to remove
+ *
+ * Nodes _must_ be removed in the exact same order from the scan list as they
+ * have been added, otherwise the internal state of the memory manager will be
+ * corrupted.
+ *
+ * When the scan list is empty, the selected memory nodes can be freed. An
+ * immediately following drm_mm_search_free with !DRM_MM_SEARCH_BEST will then
+ * return the just freed block (because its at the top of the free_stack list).
+ *
+ * Returns:
+ * True if this block should be evicted, false otherwise. Will always
+ * return false when no hole has been found.
+ */
+bool drm_mm_scan_remove_block(struct drm_mm_node *node)
+{
+	struct drm_mm *mm = node->mm;
+	struct drm_mm_node *prev_node;
+
+	mm->scanned_blocks--;
+
+	BUG_ON(!node->scanned_block);
+	node->scanned_block = 0;
+
+	prev_node = list_entry(node->node_list.prev, struct drm_mm_node,
+			       node_list);
+
+	prev_node->hole_follows = node->scanned_preceeds_hole;
+	list_add(&node->node_list, &prev_node->node_list);
+
+	 return (drm_mm_hole_node_end(node) > mm->scan_hit_start &&
+		 node->start < mm->scan_hit_end);
+}
+EXPORT_SYMBOL(drm_mm_scan_remove_block);
+
+/**
+ * drm_mm_clean - checks whether an allocator is clean
+ * @mm: drm_mm allocator to check
+ *
+ * Returns:
+ * True if the allocator is completely free, false if there's still a node
+ * allocated in it.
+ */
+bool drm_mm_clean(struct drm_mm * mm)
+{
+	struct list_head *head = &mm->head_node.node_list;
+
+	return (head->next->next == head);
+}
+EXPORT_SYMBOL(drm_mm_clean);
+
+/**
+ * drm_mm_init - initialize a drm-mm allocator
+ * @mm: the drm_mm structure to initialize
+ * @start: start of the range managed by @mm
+ * @size: end of the range managed by @mm
+ *
+ * Note that @mm must be cleared to 0 before calling this function.
+ */
+void drm_mm_init(struct drm_mm * mm, u64 start, u64 size)
+{
+	INIT_LIST_HEAD(&mm->hole_stack);
+	mm->scanned_blocks = 0;
+
+	/* Clever trick to avoid a special case in the free hole tracking. */
+	INIT_LIST_HEAD(&mm->head_node.node_list);
+	INIT_LIST_HEAD(&mm->head_node.hole_stack);
+	mm->head_node.hole_follows = 1;
+	mm->head_node.scanned_block = 0;
+	mm->head_node.scanned_prev_free = 0;
+	mm->head_node.scanned_next_free = 0;
+	mm->head_node.mm = mm;
+	mm->head_node.start = start + size;
+	mm->head_node.size = start - mm->head_node.start;
+	list_add_tail(&mm->head_node.hole_stack, &mm->hole_stack);
+
+	mm->color_adjust = NULL;
+}
+EXPORT_SYMBOL(drm_mm_init);
+
+/**
+ * drm_mm_takedown - clean up a drm_mm allocator
+ * @mm: drm_mm allocator to clean up
+ *
+ * Note that it is a bug to call this function on an allocator which is not
+ * clean.
+ */
+void drm_mm_takedown(struct drm_mm * mm)
+{
+	WARN(!list_empty(&mm->head_node.node_list),
+	     "Memory manager not clean during takedown.\n");
+}
+EXPORT_SYMBOL(drm_mm_takedown);
+
+static u64 drm_mm_debug_hole(struct drm_mm_node *entry,
+				     const char *prefix)
+{
+	u64 hole_start, hole_end, hole_size;
+
+	if (entry->hole_follows) {
+		hole_start = drm_mm_hole_node_start(entry);
+		hole_end = drm_mm_hole_node_end(entry);
+		hole_size = hole_end - hole_start;
+		pr_debug("%s %#llx-%#llx: %llu: free\n", prefix, hole_start,
+			 hole_end, hole_size);
+		return hole_size;
+	}
+
+	return 0;
+}
+
+/**
+ * drm_mm_debug_table - dump allocator state to dmesg
+ * @mm: drm_mm allocator to dump
+ * @prefix: prefix to use for dumping to dmesg
+ */
+void drm_mm_debug_table(struct drm_mm *mm, const char *prefix)
+{
+	struct drm_mm_node *entry;
+	u64 total_used = 0, total_free = 0, total = 0;
+
+	total_free += drm_mm_debug_hole(&mm->head_node, prefix);
+
+	drm_mm_for_each_node(entry, mm) {
+		pr_debug("%s %#llx-%#llx: %llu: used\n", prefix, entry->start,
+			 entry->start + entry->size, entry->size);
+		total_used += entry->size;
+		total_free += drm_mm_debug_hole(entry, prefix);
+	}
+	total = total_free + total_used;
+
+	pr_debug("%s total: %llu, used %llu free %llu\n", prefix, total,
+		 total_used, total_free);
+}
+EXPORT_SYMBOL(drm_mm_debug_table);
+
+#if defined(CONFIG_DEBUG_FS)
+static u64 drm_mm_dump_hole(struct seq_file *m, struct drm_mm_node *entry)
+{
+	u64 hole_start, hole_end, hole_size;
+
+	if (entry->hole_follows) {
+		hole_start = drm_mm_hole_node_start(entry);
+		hole_end = drm_mm_hole_node_end(entry);
+		hole_size = hole_end - hole_start;
+		seq_printf(m, "%#llx-%#llx: %llu: free\n", hole_start,
+			   hole_end, hole_size);
+		return hole_size;
+	}
+
+	return 0;
+}
+
+/**
+ * drm_mm_dump_table - dump allocator state to a seq_file
+ * @m: seq_file to dump to
+ * @mm: drm_mm allocator to dump
+ */
+int drm_mm_dump_table(struct seq_file *m, struct drm_mm *mm)
+{
+	struct drm_mm_node *entry;
+	u64 total_used = 0, total_free = 0, total = 0;
+
+	total_free += drm_mm_dump_hole(m, &mm->head_node);
+
+	drm_mm_for_each_node(entry, mm) {
+		seq_printf(m, "%#016llx-%#016llx: %llu: used\n", entry->start,
+			   entry->start + entry->size, entry->size);
+		total_used += entry->size;
+		total_free += drm_mm_dump_hole(m, entry);
+	}
+	total = total_free + total_used;
+
+	seq_printf(m, "total: %llu, used %llu free %llu\n", total,
+		   total_used, total_free);
+	return 0;
+}
+EXPORT_SYMBOL(drm_mm_dump_table);
+#endif