I've looked a bit more into this and I think we should just follow Thomas Zimmermann's idea to make this a separate module.

Otherwise we just have the code around all the time even if it is unused and implementing this should be trivial.

See how DRM_GEM_CMA_HELPER or DRM_VRAM_HELPER are done in drivers/gpu/drm/Kconfig and then have the desired effect in drivers/gpu/drm/Makefile

Should be something like ~15 lines of additional configuration which saves a bit of memory on embedded systems which just need a fbdev replacement.

Thanks,
Christian.

Am 16.11.21 um 21:18 schrieb Arunpravin:
Move the base i915 buddy allocator code into drm
- Move i915_buddy.h to include/drm
- Move i915_buddy.c to drm root folder
- Rename "i915" string with "drm" string wherever applicable
- Rename "I915" string with "DRM" string wherever applicable
- Fix header file dependencies
- Fix alignment issues
- add Makefile support for drm buddy
- export functions and write kerneldoc description
- Remove i915 selftest config check condition as buddy selftest
   will be moved to drm selftest folder

cleanup i915 buddy references in i915 driver module
and replace with drm buddy

v2:
   - include header file in alphabetical order (Thomas)
   - merged changes listed in the body section into a single patch
     to keep the build intact (Christian, Jani)

Signed-off-by: Arunpravin <arunpravin.paneersel...@amd.com>
---
  drivers/gpu/drm/Makefile                      |   2 +-
  drivers/gpu/drm/drm_buddy.c                   | 521 ++++++++++++++++++
  drivers/gpu/drm/drm_drv.c                     |   3 +
  drivers/gpu/drm/i915/Makefile                 |   1 -
  drivers/gpu/drm/i915/i915_buddy.c             | 466 ----------------
  drivers/gpu/drm/i915/i915_buddy.h             | 143 -----
  drivers/gpu/drm/i915/i915_module.c            |   3 -
  drivers/gpu/drm/i915/i915_scatterlist.c       |  11 +-
  drivers/gpu/drm/i915/i915_ttm_buddy_manager.c |  33 +-
  drivers/gpu/drm/i915/i915_ttm_buddy_manager.h |   4 +-
  include/drm/drm_buddy.h                       | 153 +++++
  11 files changed, 702 insertions(+), 638 deletions(-)
  create mode 100644 drivers/gpu/drm/drm_buddy.c
  delete mode 100644 drivers/gpu/drm/i915/i915_buddy.c
  delete mode 100644 drivers/gpu/drm/i915/i915_buddy.h
  create mode 100644 include/drm/drm_buddy.h

diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile
index 0dff40bb863c..dc61e91a3154 100644
--- a/drivers/gpu/drm/Makefile
+++ b/drivers/gpu/drm/Makefile
@@ -18,7 +18,7 @@ drm-y       :=        drm_aperture.o drm_auth.o drm_cache.o \
                drm_dumb_buffers.o drm_mode_config.o drm_vblank.o \
                drm_syncobj.o drm_lease.o drm_writeback.o drm_client.o \
                drm_client_modeset.o drm_atomic_uapi.o drm_hdcp.o \
-               drm_managed.o drm_vblank_work.o
+               drm_managed.o drm_vblank_work.o drm_buddy.o
drm-$(CONFIG_DRM_LEGACY) += drm_agpsupport.o drm_bufs.o drm_context.o drm_dma.o \
                            drm_legacy_misc.o drm_lock.o drm_memory.o 
drm_scatter.o \
diff --git a/drivers/gpu/drm/drm_buddy.c b/drivers/gpu/drm/drm_buddy.c
new file mode 100644
index 000000000000..39eb1d224bec
--- /dev/null
+++ b/drivers/gpu/drm/drm_buddy.c
@@ -0,0 +1,521 @@
+// SPDX-License-Identifier: MIT
+/*
+ * Copyright © 2021 Intel Corporation
+ */
+
+#include <linux/kmemleak.h>
+#include <linux/sizes.h>
+
+#include <drm/drm_buddy.h>
+
+static struct kmem_cache *slab_blocks;
+
+static struct drm_buddy_block *drm_block_alloc(struct drm_buddy_mm *mm,
+                                              struct drm_buddy_block *parent,
+                                              unsigned int order,
+                                              u64 offset)
+{
+       struct drm_buddy_block *block;
+
+       BUG_ON(order > DRM_BUDDY_MAX_ORDER);
+
+       block = kmem_cache_zalloc(slab_blocks, GFP_KERNEL);
+       if (!block)
+               return NULL;
+
+       block->header = offset;
+       block->header |= order;
+       block->parent = parent;
+
+       BUG_ON(block->header & DRM_BUDDY_HEADER_UNUSED);
+       return block;
+}
+
+static void drm_block_free(struct drm_buddy_mm *mm,
+                          struct drm_buddy_block *block)
+{
+       kmem_cache_free(slab_blocks, block);
+}
+
+static void mark_allocated(struct drm_buddy_block *block)
+{
+       block->header &= ~DRM_BUDDY_HEADER_STATE;
+       block->header |= DRM_BUDDY_ALLOCATED;
+
+       list_del(&block->link);
+}
+
+static void mark_free(struct drm_buddy_mm *mm,
+                     struct drm_buddy_block *block)
+{
+       block->header &= ~DRM_BUDDY_HEADER_STATE;
+       block->header |= DRM_BUDDY_FREE;
+
+       list_add(&block->link,
+                &mm->free_list[drm_buddy_block_order(block)]);
+}
+
+static void mark_split(struct drm_buddy_block *block)
+{
+       block->header &= ~DRM_BUDDY_HEADER_STATE;
+       block->header |= DRM_BUDDY_SPLIT;
+
+       list_del(&block->link);
+}
+
+/**
+ * drm_buddy_init - init memory manager
+ *
+ * @mm: DRM buddy manager to initialize
+ * @size: size in bytes to manage
+ * @chunk_size: minimum page size in bytes for our allocations
+ *
+ * Initializes the memory manager and its resources.
+ *
+ * Returns:
+ * 0 on success, error code on failure.
+ */
+int drm_buddy_init(struct drm_buddy_mm *mm, u64 size, u64 chunk_size)
+{
+       unsigned int i;
+       u64 offset;
+
+       if (size < chunk_size)
+               return -EINVAL;
+
+       if (chunk_size < PAGE_SIZE)
+               return -EINVAL;
+
+       if (!is_power_of_2(chunk_size))
+               return -EINVAL;
+
+       size = round_down(size, chunk_size);
+
+       mm->size = size;
+       mm->avail = size;
+       mm->chunk_size = chunk_size;
+       mm->max_order = ilog2(size) - ilog2(chunk_size);
+
+       BUG_ON(mm->max_order > DRM_BUDDY_MAX_ORDER);
+
+       mm->free_list = kmalloc_array(mm->max_order + 1,
+                                     sizeof(struct list_head),
+                                     GFP_KERNEL);
+       if (!mm->free_list)
+               return -ENOMEM;
+
+       for (i = 0; i <= mm->max_order; ++i)
+               INIT_LIST_HEAD(&mm->free_list[i]);
+
+       mm->n_roots = hweight64(size);
+
+       mm->roots = kmalloc_array(mm->n_roots,
+                                 sizeof(struct drm_buddy_block *),
+                                 GFP_KERNEL);
+       if (!mm->roots)
+               goto out_free_list;
+
+       offset = 0;
+       i = 0;
+
+       /*
+        * Split into power-of-two blocks, in case we are given a size that is
+        * not itself a power-of-two.
+        */
+       do {
+               struct drm_buddy_block *root;
+               unsigned int order;
+               u64 root_size;
+
+               root_size = rounddown_pow_of_two(size);
+               order = ilog2(root_size) - ilog2(chunk_size);
+
+               root = drm_block_alloc(mm, NULL, order, offset);
+               if (!root)
+                       goto out_free_roots;
+
+               mark_free(mm, root);
+
+               BUG_ON(i > mm->max_order);
+               BUG_ON(drm_buddy_block_size(mm, root) < chunk_size);
+
+               mm->roots[i] = root;
+
+               offset += root_size;
+               size -= root_size;
+               i++;
+       } while (size);
+
+       return 0;
+
+out_free_roots:
+       while (i--)
+               drm_block_free(mm, mm->roots[i]);
+       kfree(mm->roots);
+out_free_list:
+       kfree(mm->free_list);
+       return -ENOMEM;
+}
+EXPORT_SYMBOL(drm_buddy_init);
+
+/**
+ * drm_buddy_fini - tear down the memory manager
+ *
+ * @mm: DRM buddy manager to free
+ *
+ * Cleanup memory manager resources and the freelist
+ */
+void drm_buddy_fini(struct drm_buddy_mm *mm)
+{
+       int i;
+
+       for (i = 0; i < mm->n_roots; ++i) {
+               WARN_ON(!drm_buddy_block_is_free(mm->roots[i]));
+               drm_block_free(mm, mm->roots[i]);
+       }
+
+       WARN_ON(mm->avail != mm->size);
+
+       kfree(mm->roots);
+       kfree(mm->free_list);
+}
+EXPORT_SYMBOL(drm_buddy_fini);
+
+static int split_block(struct drm_buddy_mm *mm,
+                      struct drm_buddy_block *block)
+{
+       unsigned int block_order = drm_buddy_block_order(block) - 1;
+       u64 offset = drm_buddy_block_offset(block);
+
+       BUG_ON(!drm_buddy_block_is_free(block));
+       BUG_ON(!drm_buddy_block_order(block));
+
+       block->left = drm_block_alloc(mm, block, block_order, offset);
+       if (!block->left)
+               return -ENOMEM;
+
+       block->right = drm_block_alloc(mm, block, block_order,
+                                       offset + (mm->chunk_size << 
block_order));
+       if (!block->right) {
+               drm_block_free(mm, block->left);
+               return -ENOMEM;
+       }
+
+       mark_free(mm, block->left);
+       mark_free(mm, block->right);
+
+       mark_split(block);
+
+       return 0;
+}
+
+static struct drm_buddy_block *
+get_buddy(struct drm_buddy_block *block)
+{
+       struct drm_buddy_block *parent;
+
+       parent = block->parent;
+       if (!parent)
+               return NULL;
+
+       if (parent->left == block)
+               return parent->right;
+
+       return parent->left;
+}
+
+static void __drm_buddy_free(struct drm_buddy_mm *mm,
+                            struct drm_buddy_block *block)
+{
+       struct drm_buddy_block *parent;
+
+       while ((parent = block->parent)) {
+               struct drm_buddy_block *buddy;
+
+               buddy = get_buddy(block);
+
+               if (!drm_buddy_block_is_free(buddy))
+                       break;
+
+               list_del(&buddy->link);
+
+               drm_block_free(mm, block);
+               drm_block_free(mm, buddy);
+
+               block = parent;
+       }
+
+       mark_free(mm, block);
+}
+
+void drm_buddy_free(struct drm_buddy_mm *mm,
+                   struct drm_buddy_block *block)
+{
+       BUG_ON(!drm_buddy_block_is_allocated(block));
+       mm->avail += drm_buddy_block_size(mm, block);
+       __drm_buddy_free(mm, block);
+}
+
+/**
+ * drm_buddy_free_list - free blocks
+ *
+ * @mm: DRM buddy manager
+ * @objects: input list head to free blocks
+ */
+void drm_buddy_free_list(struct drm_buddy_mm *mm, struct list_head *objects)
+{
+       struct drm_buddy_block *block, *on;
+
+       list_for_each_entry_safe(block, on, objects, link) {
+               drm_buddy_free(mm, block);
+               cond_resched();
+       }
+       INIT_LIST_HEAD(objects);
+}
+EXPORT_SYMBOL(drm_buddy_free_list);
+
+/**
+ * drm_buddy_alloc - allocate power-of-two blocks
+ *
+ * @mm: DRM buddy manager to allocate from
+ * @order: size of the allocation
+ *
+ * The order value here translates to:
+ *
+ * 0 = 2^0 * mm->chunk_size
+ * 1 = 2^1 * mm->chunk_size
+ * 2 = 2^2 * mm->chunk_size
+ *
+ * Returns:
+ * allocated ptr to the &drm_buddy_block on success
+ */
+struct drm_buddy_block *
+drm_buddy_alloc(struct drm_buddy_mm *mm, unsigned int order)
+{
+       struct drm_buddy_block *block = NULL;
+       unsigned int i;
+       int err;
+
+       for (i = order; i <= mm->max_order; ++i) {
+               block = list_first_entry_or_null(&mm->free_list[i],
+                                                struct drm_buddy_block,
+                                                link);
+               if (block)
+                       break;
+       }
+
+       if (!block)
+               return ERR_PTR(-ENOSPC);
+
+       BUG_ON(!drm_buddy_block_is_free(block));
+
+       while (i != order) {
+               err = split_block(mm, block);
+               if (unlikely(err))
+                       goto out_free;
+
+               /* Go low */
+               block = block->left;
+               i--;
+       }
+
+       mark_allocated(block);
+       mm->avail -= drm_buddy_block_size(mm, block);
+       kmemleak_update_trace(block);
+       return block;
+
+out_free:
+       if (i != order)
+               __drm_buddy_free(mm, block);
+       return ERR_PTR(err);
+}
+EXPORT_SYMBOL(drm_buddy_alloc);
+
+static inline bool overlaps(u64 s1, u64 e1, u64 s2, u64 e2)
+{
+       return s1 <= e2 && e1 >= s2;
+}
+
+static inline bool contains(u64 s1, u64 e1, u64 s2, u64 e2)
+{
+       return s1 <= s2 && e1 >= e2;
+}
+
+/**
+ * drm_buddy_alloc_range - allocate range
+ *
+ * @mm: DRM buddy manager to allocate from
+ * @blocks: output list head to add allocated blocks
+ * @start: start of the allowed range for this block
+ * @size: size of the allocation
+ *
+ * Intended for pre-allocating portions of the address space, for example to
+ * reserve a block for the initial framebuffer or similar, hence the 
expectation
+ * here is that drm_buddy_alloc() is still the main vehicle for
+ * allocations, so if that's not the case then the drm_mm range allocator is
+ * probably a much better fit, and so you should probably go use that instead.
+ *
+ * Note that it's safe to chain together multiple alloc_ranges
+ * with the same blocks list
+ *
+ * Returns:
+ * 0 on success, error code on failure.
+ */
+int drm_buddy_alloc_range(struct drm_buddy_mm *mm,
+                         struct list_head *blocks,
+                         u64 start, u64 size)
+{
+       struct drm_buddy_block *block;
+       struct drm_buddy_block *buddy;
+       LIST_HEAD(allocated);
+       LIST_HEAD(dfs);
+       u64 end;
+       int err;
+       int i;
+
+       if (size < mm->chunk_size)
+               return -EINVAL;
+
+       if (!IS_ALIGNED(size | start, mm->chunk_size))
+               return -EINVAL;
+
+       if (range_overflows(start, size, mm->size))
+               return -EINVAL;
+
+       for (i = 0; i < mm->n_roots; ++i)
+               list_add_tail(&mm->roots[i]->tmp_link, &dfs);
+
+       end = start + size - 1;
+
+       do {
+               u64 block_start;
+               u64 block_end;
+
+               block = list_first_entry_or_null(&dfs,
+                                                struct drm_buddy_block,
+                                                tmp_link);
+               if (!block)
+                       break;
+
+               list_del(&block->tmp_link);
+
+               block_start = drm_buddy_block_offset(block);
+               block_end = block_start + drm_buddy_block_size(mm, block) - 1;
+
+               if (!overlaps(start, end, block_start, block_end))
+                       continue;
+
+               if (drm_buddy_block_is_allocated(block)) {
+                       err = -ENOSPC;
+                       goto err_free;
+               }
+
+               if (contains(start, end, block_start, block_end)) {
+                       if (!drm_buddy_block_is_free(block)) {
+                               err = -ENOSPC;
+                               goto err_free;
+                       }
+
+                       mark_allocated(block);
+                       mm->avail -= drm_buddy_block_size(mm, block);
+                       list_add_tail(&block->link, &allocated);
+                       continue;
+               }
+
+               if (!drm_buddy_block_is_split(block)) {
+                       err = split_block(mm, block);
+                       if (unlikely(err))
+                               goto err_undo;
+               }
+
+               list_add(&block->right->tmp_link, &dfs);
+               list_add(&block->left->tmp_link, &dfs);
+       } while (1);
+
+       list_splice_tail(&allocated, blocks);
+       return 0;
+
+err_undo:
+       /*
+        * We really don't want to leave around a bunch of split blocks, since
+        * bigger is better, so make sure we merge everything back before we
+        * free the allocated blocks.
+        */
+       buddy = get_buddy(block);
+       if (buddy &&
+           (drm_buddy_block_is_free(block) &&
+            drm_buddy_block_is_free(buddy)))
+               __drm_buddy_free(mm, block);
+
+err_free:
+       drm_buddy_free_list(mm, &allocated);
+       return err;
+}
+EXPORT_SYMBOL(drm_buddy_alloc_range);
+
+/**
+ * drm_buddy_block_print - print block information
+ *
+ * @mm: DRM buddy manager
+ * @block: DRM buddy block
+ * @p: DRM printer to use
+ */
+void drm_buddy_block_print(struct drm_buddy_mm *mm,
+                          struct drm_buddy_block *block,
+                          struct drm_printer *p)
+{
+       u64 start = drm_buddy_block_offset(block);
+       u64 size = drm_buddy_block_size(mm, block);
+
+       drm_printf(p, "%#018llx-%#018llx: %llu\n", start, start + size, size);
+}
+EXPORT_SYMBOL(drm_buddy_block_print);
+
+/**
+ * drm_buddy_print - print allocator state
+ *
+ * @mm: DRM buddy manager
+ * @p: DRM printer to use
+ */
+void drm_buddy_print(struct drm_buddy_mm *mm, struct drm_printer *p)
+{
+       int order;
+
+       drm_printf(p, "chunk_size: %lluKiB, total: %lluMiB, free: %lluMiB\n",
+                  mm->chunk_size >> 10, mm->size >> 20, mm->avail >> 20);
+
+       for (order = mm->max_order; order >= 0; order--) {
+               struct drm_buddy_block *block;
+               u64 count = 0, free;
+
+               list_for_each_entry(block, &mm->free_list[order], link) {
+                       BUG_ON(!drm_buddy_block_is_free(block));
+                       count++;
+               }
+
+               drm_printf(p, "order-%d ", order);
+
+               free = count * (mm->chunk_size << order);
+               if (free < SZ_1M)
+                       drm_printf(p, "free: %lluKiB", free >> 10);
+               else
+                       drm_printf(p, "free: %lluMiB", free >> 20);
+
+               drm_printf(p, ", pages: %llu\n", count);
+       }
+}
+EXPORT_SYMBOL(drm_buddy_print);
+
+void drm_buddy_module_exit(void)
+{
+       kmem_cache_destroy(slab_blocks);
+}
+
+int __init drm_buddy_module_init(void)
+{
+       slab_blocks = KMEM_CACHE(drm_buddy_block, 0);
+       if (!slab_blocks)
+               return -ENOMEM;
+
+       return 0;
+}
diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
index 7a5097467ba5..5d5e46e60586 100644
--- a/drivers/gpu/drm/drm_drv.c
+++ b/drivers/gpu/drm/drm_drv.c
@@ -35,6 +35,7 @@
  #include <linux/slab.h>
  #include <linux/srcu.h>
+#include <drm/drm_buddy.h>
  #include <drm/drm_cache.h>
  #include <drm/drm_client.h>
  #include <drm/drm_color_mgmt.h>
@@ -1034,6 +1035,7 @@ static void drm_core_exit(void)
        drm_sysfs_destroy();
        idr_destroy(&drm_minors_idr);
        drm_connector_ida_destroy();
+       drm_buddy_module_exit();
  }
static int __init drm_core_init(void)
@@ -1043,6 +1045,7 @@ static int __init drm_core_init(void)
        drm_connector_ida_init();
        idr_init(&drm_minors_idr);
        drm_memcpy_init_early();
+       drm_buddy_module_init();
ret = drm_sysfs_init();
        if (ret < 0) {
diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile
index 467872cca027..fc5ca8c4ccb2 100644
--- a/drivers/gpu/drm/i915/Makefile
+++ b/drivers/gpu/drm/i915/Makefile
@@ -161,7 +161,6 @@ gem-y += \
  i915-y += \
          $(gem-y) \
          i915_active.o \
-         i915_buddy.o \
          i915_cmd_parser.o \
          i915_gem_evict.o \
          i915_gem_gtt.o \
diff --git a/drivers/gpu/drm/i915/i915_buddy.c 
b/drivers/gpu/drm/i915/i915_buddy.c
deleted file mode 100644
index 6e2ad68f8f3f..000000000000
--- a/drivers/gpu/drm/i915/i915_buddy.c
+++ /dev/null
@@ -1,466 +0,0 @@
-// SPDX-License-Identifier: MIT
-/*
- * Copyright © 2021 Intel Corporation
- */
-
-#include <linux/kmemleak.h>
-#include <linux/sizes.h>
-
-#include "i915_buddy.h"
-
-#include "i915_gem.h"
-#include "i915_utils.h"
-
-static struct kmem_cache *slab_blocks;
-
-static struct i915_buddy_block *i915_block_alloc(struct i915_buddy_mm *mm,
-                                                struct i915_buddy_block 
*parent,
-                                                unsigned int order,
-                                                u64 offset)
-{
-       struct i915_buddy_block *block;
-
-       GEM_BUG_ON(order > I915_BUDDY_MAX_ORDER);
-
-       block = kmem_cache_zalloc(slab_blocks, GFP_KERNEL);
-       if (!block)
-               return NULL;
-
-       block->header = offset;
-       block->header |= order;
-       block->parent = parent;
-
-       GEM_BUG_ON(block->header & I915_BUDDY_HEADER_UNUSED);
-       return block;
-}
-
-static void i915_block_free(struct i915_buddy_mm *mm,
-                           struct i915_buddy_block *block)
-{
-       kmem_cache_free(slab_blocks, block);
-}
-
-static void mark_allocated(struct i915_buddy_block *block)
-{
-       block->header &= ~I915_BUDDY_HEADER_STATE;
-       block->header |= I915_BUDDY_ALLOCATED;
-
-       list_del(&block->link);
-}
-
-static void mark_free(struct i915_buddy_mm *mm,
-                     struct i915_buddy_block *block)
-{
-       block->header &= ~I915_BUDDY_HEADER_STATE;
-       block->header |= I915_BUDDY_FREE;
-
-       list_add(&block->link,
-                &mm->free_list[i915_buddy_block_order(block)]);
-}
-
-static void mark_split(struct i915_buddy_block *block)
-{
-       block->header &= ~I915_BUDDY_HEADER_STATE;
-       block->header |= I915_BUDDY_SPLIT;
-
-       list_del(&block->link);
-}
-
-int i915_buddy_init(struct i915_buddy_mm *mm, u64 size, u64 chunk_size)
-{
-       unsigned int i;
-       u64 offset;
-
-       if (size < chunk_size)
-               return -EINVAL;
-
-       if (chunk_size < PAGE_SIZE)
-               return -EINVAL;
-
-       if (!is_power_of_2(chunk_size))
-               return -EINVAL;
-
-       size = round_down(size, chunk_size);
-
-       mm->size = size;
-       mm->avail = size;
-       mm->chunk_size = chunk_size;
-       mm->max_order = ilog2(size) - ilog2(chunk_size);
-
-       GEM_BUG_ON(mm->max_order > I915_BUDDY_MAX_ORDER);
-
-       mm->free_list = kmalloc_array(mm->max_order + 1,
-                                     sizeof(struct list_head),
-                                     GFP_KERNEL);
-       if (!mm->free_list)
-               return -ENOMEM;
-
-       for (i = 0; i <= mm->max_order; ++i)
-               INIT_LIST_HEAD(&mm->free_list[i]);
-
-       mm->n_roots = hweight64(size);
-
-       mm->roots = kmalloc_array(mm->n_roots,
-                                 sizeof(struct i915_buddy_block *),
-                                 GFP_KERNEL);
-       if (!mm->roots)
-               goto out_free_list;
-
-       offset = 0;
-       i = 0;
-
-       /*
-        * Split into power-of-two blocks, in case we are given a size that is
-        * not itself a power-of-two.
-        */
-       do {
-               struct i915_buddy_block *root;
-               unsigned int order;
-               u64 root_size;
-
-               root_size = rounddown_pow_of_two(size);
-               order = ilog2(root_size) - ilog2(chunk_size);
-
-               root = i915_block_alloc(mm, NULL, order, offset);
-               if (!root)
-                       goto out_free_roots;
-
-               mark_free(mm, root);
-
-               GEM_BUG_ON(i > mm->max_order);
-               GEM_BUG_ON(i915_buddy_block_size(mm, root) < chunk_size);
-
-               mm->roots[i] = root;
-
-               offset += root_size;
-               size -= root_size;
-               i++;
-       } while (size);
-
-       return 0;
-
-out_free_roots:
-       while (i--)
-               i915_block_free(mm, mm->roots[i]);
-       kfree(mm->roots);
-out_free_list:
-       kfree(mm->free_list);
-       return -ENOMEM;
-}
-
-void i915_buddy_fini(struct i915_buddy_mm *mm)
-{
-       int i;
-
-       for (i = 0; i < mm->n_roots; ++i) {
-               GEM_WARN_ON(!i915_buddy_block_is_free(mm->roots[i]));
-               i915_block_free(mm, mm->roots[i]);
-       }
-
-       GEM_WARN_ON(mm->avail != mm->size);
-
-       kfree(mm->roots);
-       kfree(mm->free_list);
-}
-
-static int split_block(struct i915_buddy_mm *mm,
-                      struct i915_buddy_block *block)
-{
-       unsigned int block_order = i915_buddy_block_order(block) - 1;
-       u64 offset = i915_buddy_block_offset(block);
-
-       GEM_BUG_ON(!i915_buddy_block_is_free(block));
-       GEM_BUG_ON(!i915_buddy_block_order(block));
-
-       block->left = i915_block_alloc(mm, block, block_order, offset);
-       if (!block->left)
-               return -ENOMEM;
-
-       block->right = i915_block_alloc(mm, block, block_order,
-                                       offset + (mm->chunk_size << 
block_order));
-       if (!block->right) {
-               i915_block_free(mm, block->left);
-               return -ENOMEM;
-       }
-
-       mark_free(mm, block->left);
-       mark_free(mm, block->right);
-
-       mark_split(block);
-
-       return 0;
-}
-
-static struct i915_buddy_block *
-get_buddy(struct i915_buddy_block *block)
-{
-       struct i915_buddy_block *parent;
-
-       parent = block->parent;
-       if (!parent)
-               return NULL;
-
-       if (parent->left == block)
-               return parent->right;
-
-       return parent->left;
-}
-
-static void __i915_buddy_free(struct i915_buddy_mm *mm,
-                             struct i915_buddy_block *block)
-{
-       struct i915_buddy_block *parent;
-
-       while ((parent = block->parent)) {
-               struct i915_buddy_block *buddy;
-
-               buddy = get_buddy(block);
-
-               if (!i915_buddy_block_is_free(buddy))
-                       break;
-
-               list_del(&buddy->link);
-
-               i915_block_free(mm, block);
-               i915_block_free(mm, buddy);
-
-               block = parent;
-       }
-
-       mark_free(mm, block);
-}
-
-void i915_buddy_free(struct i915_buddy_mm *mm,
-                    struct i915_buddy_block *block)
-{
-       GEM_BUG_ON(!i915_buddy_block_is_allocated(block));
-       mm->avail += i915_buddy_block_size(mm, block);
-       __i915_buddy_free(mm, block);
-}
-
-void i915_buddy_free_list(struct i915_buddy_mm *mm, struct list_head *objects)
-{
-       struct i915_buddy_block *block, *on;
-
-       list_for_each_entry_safe(block, on, objects, link) {
-               i915_buddy_free(mm, block);
-               cond_resched();
-       }
-       INIT_LIST_HEAD(objects);
-}
-
-/*
- * Allocate power-of-two block. The order value here translates to:
- *
- *   0 = 2^0 * mm->chunk_size
- *   1 = 2^1 * mm->chunk_size
- *   2 = 2^2 * mm->chunk_size
- *   ...
- */
-struct i915_buddy_block *
-i915_buddy_alloc(struct i915_buddy_mm *mm, unsigned int order)
-{
-       struct i915_buddy_block *block = NULL;
-       unsigned int i;
-       int err;
-
-       for (i = order; i <= mm->max_order; ++i) {
-               block = list_first_entry_or_null(&mm->free_list[i],
-                                                struct i915_buddy_block,
-                                                link);
-               if (block)
-                       break;
-       }
-
-       if (!block)
-               return ERR_PTR(-ENOSPC);
-
-       GEM_BUG_ON(!i915_buddy_block_is_free(block));
-
-       while (i != order) {
-               err = split_block(mm, block);
-               if (unlikely(err))
-                       goto out_free;
-
-               /* Go low */
-               block = block->left;
-               i--;
-       }
-
-       mark_allocated(block);
-       mm->avail -= i915_buddy_block_size(mm, block);
-       kmemleak_update_trace(block);
-       return block;
-
-out_free:
-       if (i != order)
-               __i915_buddy_free(mm, block);
-       return ERR_PTR(err);
-}
-
-static inline bool overlaps(u64 s1, u64 e1, u64 s2, u64 e2)
-{
-       return s1 <= e2 && e1 >= s2;
-}
-
-static inline bool contains(u64 s1, u64 e1, u64 s2, u64 e2)
-{
-       return s1 <= s2 && e1 >= e2;
-}
-
-/*
- * Allocate range. Note that it's safe to chain together multiple alloc_ranges
- * with the same blocks list.
- *
- * Intended for pre-allocating portions of the address space, for example to
- * reserve a block for the initial framebuffer or similar, hence the 
expectation
- * here is that i915_buddy_alloc() is still the main vehicle for
- * allocations, so if that's not the case then the drm_mm range allocator is
- * probably a much better fit, and so you should probably go use that instead.
- */
-int i915_buddy_alloc_range(struct i915_buddy_mm *mm,
-                          struct list_head *blocks,
-                          u64 start, u64 size)
-{
-       struct i915_buddy_block *block;
-       struct i915_buddy_block *buddy;
-       LIST_HEAD(allocated);
-       LIST_HEAD(dfs);
-       u64 end;
-       int err;
-       int i;
-
-       if (size < mm->chunk_size)
-               return -EINVAL;
-
-       if (!IS_ALIGNED(size | start, mm->chunk_size))
-               return -EINVAL;
-
-       if (range_overflows(start, size, mm->size))
-               return -EINVAL;
-
-       for (i = 0; i < mm->n_roots; ++i)
-               list_add_tail(&mm->roots[i]->tmp_link, &dfs);
-
-       end = start + size - 1;
-
-       do {
-               u64 block_start;
-               u64 block_end;
-
-               block = list_first_entry_or_null(&dfs,
-                                                struct i915_buddy_block,
-                                                tmp_link);
-               if (!block)
-                       break;
-
-               list_del(&block->tmp_link);
-
-               block_start = i915_buddy_block_offset(block);
-               block_end = block_start + i915_buddy_block_size(mm, block) - 1;
-
-               if (!overlaps(start, end, block_start, block_end))
-                       continue;
-
-               if (i915_buddy_block_is_allocated(block)) {
-                       err = -ENOSPC;
-                       goto err_free;
-               }
-
-               if (contains(start, end, block_start, block_end)) {
-                       if (!i915_buddy_block_is_free(block)) {
-                               err = -ENOSPC;
-                               goto err_free;
-                       }
-
-                       mark_allocated(block);
-                       mm->avail -= i915_buddy_block_size(mm, block);
-                       list_add_tail(&block->link, &allocated);
-                       continue;
-               }
-
-               if (!i915_buddy_block_is_split(block)) {
-                       err = split_block(mm, block);
-                       if (unlikely(err))
-                               goto err_undo;
-               }
-
-               list_add(&block->right->tmp_link, &dfs);
-               list_add(&block->left->tmp_link, &dfs);
-       } while (1);
-
-       list_splice_tail(&allocated, blocks);
-       return 0;
-
-err_undo:
-       /*
-        * We really don't want to leave around a bunch of split blocks, since
-        * bigger is better, so make sure we merge everything back before we
-        * free the allocated blocks.
-        */
-       buddy = get_buddy(block);
-       if (buddy &&
-           (i915_buddy_block_is_free(block) &&
-            i915_buddy_block_is_free(buddy)))
-               __i915_buddy_free(mm, block);
-
-err_free:
-       i915_buddy_free_list(mm, &allocated);
-       return err;
-}
-
-void i915_buddy_block_print(struct i915_buddy_mm *mm,
-                           struct i915_buddy_block *block,
-                           struct drm_printer *p)
-{
-       u64 start = i915_buddy_block_offset(block);
-       u64 size = i915_buddy_block_size(mm, block);
-
-       drm_printf(p, "%#018llx-%#018llx: %llu\n", start, start + size, size);
-}
-
-void i915_buddy_print(struct i915_buddy_mm *mm, struct drm_printer *p)
-{
-       int order;
-
-       drm_printf(p, "chunk_size: %lluKiB, total: %lluMiB, free: %lluMiB\n",
-                  mm->chunk_size >> 10, mm->size >> 20, mm->avail >> 20);
-
-       for (order = mm->max_order; order >= 0; order--) {
-               struct i915_buddy_block *block;
-               u64 count = 0, free;
-
-               list_for_each_entry(block, &mm->free_list[order], link) {
-                       GEM_BUG_ON(!i915_buddy_block_is_free(block));
-                       count++;
-               }
-
-               drm_printf(p, "order-%d ", order);
-
-               free = count * (mm->chunk_size << order);
-               if (free < SZ_1M)
-                       drm_printf(p, "free: %lluKiB", free >> 10);
-               else
-                       drm_printf(p, "free: %lluMiB", free >> 20);
-
-               drm_printf(p, ", pages: %llu\n", count);
-       }
-}
-
-#if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
-#include "selftests/i915_buddy.c"
-#endif
-
-void i915_buddy_module_exit(void)
-{
-       kmem_cache_destroy(slab_blocks);
-}
-
-int __init i915_buddy_module_init(void)
-{
-       slab_blocks = KMEM_CACHE(i915_buddy_block, 0);
-       if (!slab_blocks)
-               return -ENOMEM;
-
-       return 0;
-}
diff --git a/drivers/gpu/drm/i915/i915_buddy.h 
b/drivers/gpu/drm/i915/i915_buddy.h
deleted file mode 100644
index 7077742112ac..000000000000
--- a/drivers/gpu/drm/i915/i915_buddy.h
+++ /dev/null
@@ -1,143 +0,0 @@
-/* SPDX-License-Identifier: MIT */
-/*
- * Copyright © 2021 Intel Corporation
- */
-
-#ifndef __I915_BUDDY_H__
-#define __I915_BUDDY_H__
-
-#include <linux/bitops.h>
-#include <linux/list.h>
-#include <linux/slab.h>
-
-#include <drm/drm_print.h>
-
-struct i915_buddy_block {
-#define I915_BUDDY_HEADER_OFFSET GENMASK_ULL(63, 12)
-#define I915_BUDDY_HEADER_STATE  GENMASK_ULL(11, 10)
-#define   I915_BUDDY_ALLOCATED    (1 << 10)
-#define   I915_BUDDY_FREE         (2 << 10)
-#define   I915_BUDDY_SPLIT        (3 << 10)
-/* Free to be used, if needed in the future */
-#define I915_BUDDY_HEADER_UNUSED GENMASK_ULL(9, 6)
-#define I915_BUDDY_HEADER_ORDER  GENMASK_ULL(5, 0)
-       u64 header;
-
-       struct i915_buddy_block *left;
-       struct i915_buddy_block *right;
-       struct i915_buddy_block *parent;
-
-       void *private; /* owned by creator */
-
-       /*
-        * While the block is allocated by the user through i915_buddy_alloc*,
-        * the user has ownership of the link, for example to maintain within
-        * a list, if so desired. As soon as the block is freed with
-        * i915_buddy_free* ownership is given back to the mm.
-        */
-       struct list_head link;
-       struct list_head tmp_link;
-};
-
-/* Order-zero must be at least PAGE_SIZE */
-#define I915_BUDDY_MAX_ORDER (63 - PAGE_SHIFT)
-
-/*
- * Binary Buddy System.
- *
- * Locking should be handled by the user, a simple mutex around
- * i915_buddy_alloc* and i915_buddy_free* should suffice.
- */
-struct i915_buddy_mm {
-       /* Maintain a free list for each order. */
-       struct list_head *free_list;
-
-       /*
-        * Maintain explicit binary tree(s) to track the allocation of the
-        * address space. This gives us a simple way of finding a buddy block
-        * and performing the potentially recursive merge step when freeing a
-        * block.  Nodes are either allocated or free, in which case they will
-        * also exist on the respective free list.
-        */
-       struct i915_buddy_block **roots;
-
-       /*
-        * Anything from here is public, and remains static for the lifetime of
-        * the mm. Everything above is considered do-not-touch.
-        */
-       unsigned int n_roots;
-       unsigned int max_order;
-
-       /* Must be at least PAGE_SIZE */
-       u64 chunk_size;
-       u64 size;
-       u64 avail;
-};
-
-static inline u64
-i915_buddy_block_offset(struct i915_buddy_block *block)
-{
-       return block->header & I915_BUDDY_HEADER_OFFSET;
-}
-
-static inline unsigned int
-i915_buddy_block_order(struct i915_buddy_block *block)
-{
-       return block->header & I915_BUDDY_HEADER_ORDER;
-}
-
-static inline unsigned int
-i915_buddy_block_state(struct i915_buddy_block *block)
-{
-       return block->header & I915_BUDDY_HEADER_STATE;
-}
-
-static inline bool
-i915_buddy_block_is_allocated(struct i915_buddy_block *block)
-{
-       return i915_buddy_block_state(block) == I915_BUDDY_ALLOCATED;
-}
-
-static inline bool
-i915_buddy_block_is_free(struct i915_buddy_block *block)
-{
-       return i915_buddy_block_state(block) == I915_BUDDY_FREE;
-}
-
-static inline bool
-i915_buddy_block_is_split(struct i915_buddy_block *block)
-{
-       return i915_buddy_block_state(block) == I915_BUDDY_SPLIT;
-}
-
-static inline u64
-i915_buddy_block_size(struct i915_buddy_mm *mm,
-                     struct i915_buddy_block *block)
-{
-       return mm->chunk_size << i915_buddy_block_order(block);
-}
-
-int i915_buddy_init(struct i915_buddy_mm *mm, u64 size, u64 chunk_size);
-
-void i915_buddy_fini(struct i915_buddy_mm *mm);
-
-struct i915_buddy_block *
-i915_buddy_alloc(struct i915_buddy_mm *mm, unsigned int order);
-
-int i915_buddy_alloc_range(struct i915_buddy_mm *mm,
-                          struct list_head *blocks,
-                          u64 start, u64 size);
-
-void i915_buddy_free(struct i915_buddy_mm *mm, struct i915_buddy_block *block);
-
-void i915_buddy_free_list(struct i915_buddy_mm *mm, struct list_head *objects);
-
-void i915_buddy_print(struct i915_buddy_mm *mm, struct drm_printer *p);
-void i915_buddy_block_print(struct i915_buddy_mm *mm,
-                           struct i915_buddy_block *block,
-                           struct drm_printer *p);
-
-void i915_buddy_module_exit(void);
-int i915_buddy_module_init(void);
-
-#endif
diff --git a/drivers/gpu/drm/i915/i915_module.c 
b/drivers/gpu/drm/i915/i915_module.c
index c7507266aa83..355681dbd7a8 100644
--- a/drivers/gpu/drm/i915/i915_module.c
+++ b/drivers/gpu/drm/i915/i915_module.c
@@ -9,7 +9,6 @@
  #include "gem/i915_gem_context.h"
  #include "gem/i915_gem_object.h"
  #include "i915_active.h"
-#include "i915_buddy.h"
  #include "i915_params.h"
  #include "i915_pci.h"
  #include "i915_perf.h"
@@ -50,8 +49,6 @@ static const struct {
        { .init = i915_check_nomodeset },
        { .init = i915_active_module_init,
          .exit = i915_active_module_exit },
-       { .init = i915_buddy_module_init,
-         .exit = i915_buddy_module_exit },
        { .init = i915_context_module_init,
          .exit = i915_context_module_exit },
        { .init = i915_gem_context_module_init,
diff --git a/drivers/gpu/drm/i915/i915_scatterlist.c 
b/drivers/gpu/drm/i915/i915_scatterlist.c
index 4a6712dca838..84d622aa32d2 100644
--- a/drivers/gpu/drm/i915/i915_scatterlist.c
+++ b/drivers/gpu/drm/i915/i915_scatterlist.c
@@ -5,10 +5,9 @@
   */
#include "i915_scatterlist.h"
-
-#include "i915_buddy.h"
  #include "i915_ttm_buddy_manager.h"
+#include <drm/drm_buddy.h>
  #include <drm/drm_mm.h>
#include <linux/slab.h>
@@ -126,9 +125,9 @@ struct sg_table *i915_sg_from_buddy_resource(struct 
ttm_resource *res,
        struct i915_ttm_buddy_resource *bman_res = to_ttm_buddy_resource(res);
        const u64 size = res->num_pages << PAGE_SHIFT;
        const u64 max_segment = rounddown(UINT_MAX, PAGE_SIZE);
-       struct i915_buddy_mm *mm = bman_res->mm;
+       struct drm_buddy_mm *mm = bman_res->mm;
        struct list_head *blocks = &bman_res->blocks;
-       struct i915_buddy_block *block;
+       struct drm_buddy_block *block;
        struct scatterlist *sg;
        struct sg_table *st;
        resource_size_t prev_end;
@@ -151,8 +150,8 @@ struct sg_table *i915_sg_from_buddy_resource(struct 
ttm_resource *res,
        list_for_each_entry(block, blocks, link) {
                u64 block_size, offset;
- block_size = min_t(u64, size, i915_buddy_block_size(mm, block));
-               offset = i915_buddy_block_offset(block);
+               block_size = min_t(u64, size, drm_buddy_block_size(mm, block));
+               offset = drm_buddy_block_offset(block);
while (block_size) {
                        u64 len;
diff --git a/drivers/gpu/drm/i915/i915_ttm_buddy_manager.c 
b/drivers/gpu/drm/i915/i915_ttm_buddy_manager.c
index d59fbb019032..c4b70cb8c248 100644
--- a/drivers/gpu/drm/i915/i915_ttm_buddy_manager.c
+++ b/drivers/gpu/drm/i915/i915_ttm_buddy_manager.c
@@ -8,14 +8,15 @@
  #include <drm/ttm/ttm_bo_driver.h>
  #include <drm/ttm/ttm_placement.h>
+#include <drm/drm_buddy.h>
+
  #include "i915_ttm_buddy_manager.h"
-#include "i915_buddy.h"
  #include "i915_gem.h"
struct i915_ttm_buddy_manager {
        struct ttm_resource_manager manager;
-       struct i915_buddy_mm mm;
+       struct drm_buddy_mm mm;
        struct list_head reserved;
        struct mutex lock;
        u64 default_page_size;
@@ -34,7 +35,7 @@ static int i915_ttm_buddy_man_alloc(struct 
ttm_resource_manager *man,
  {
        struct i915_ttm_buddy_manager *bman = to_buddy_manager(man);
        struct i915_ttm_buddy_resource *bman_res;
-       struct i915_buddy_mm *mm = &bman->mm;
+       struct drm_buddy_mm *mm = &bman->mm;
        unsigned long n_pages;
        unsigned int min_order;
        u64 min_page_size;
@@ -73,7 +74,7 @@ static int i915_ttm_buddy_man_alloc(struct 
ttm_resource_manager *man,
        n_pages = size >> ilog2(mm->chunk_size);
do {
-               struct i915_buddy_block *block;
+               struct drm_buddy_block *block;
                unsigned int order;
order = fls(n_pages) - 1;
@@ -82,7 +83,7 @@ static int i915_ttm_buddy_man_alloc(struct 
ttm_resource_manager *man,
do {
                        mutex_lock(&bman->lock);
-                       block = i915_buddy_alloc(mm, order);
+                       block = drm_buddy_alloc(mm, order);
                        mutex_unlock(&bman->lock);
                        if (!IS_ERR(block))
                                break;
@@ -106,7 +107,7 @@ static int i915_ttm_buddy_man_alloc(struct 
ttm_resource_manager *man,
err_free_blocks:
        mutex_lock(&bman->lock);
-       i915_buddy_free_list(mm, &bman_res->blocks);
+       drm_buddy_free_list(mm, &bman_res->blocks);
        mutex_unlock(&bman->lock);
  err_free_res:
        kfree(bman_res);
@@ -120,7 +121,7 @@ static void i915_ttm_buddy_man_free(struct 
ttm_resource_manager *man,
        struct i915_ttm_buddy_manager *bman = to_buddy_manager(man);
mutex_lock(&bman->lock);
-       i915_buddy_free_list(&bman->mm, &bman_res->blocks);
+       drm_buddy_free_list(&bman->mm, &bman_res->blocks);
        mutex_unlock(&bman->lock);
kfree(bman_res);
@@ -130,17 +131,17 @@ static void i915_ttm_buddy_man_debug(struct 
ttm_resource_manager *man,
                                     struct drm_printer *printer)
  {
        struct i915_ttm_buddy_manager *bman = to_buddy_manager(man);
-       struct i915_buddy_block *block;
+       struct drm_buddy_block *block;
mutex_lock(&bman->lock);
        drm_printf(printer, "default_page_size: %lluKiB\n",
                   bman->default_page_size >> 10);
- i915_buddy_print(&bman->mm, printer);
+       drm_buddy_print(&bman->mm, printer);
drm_printf(printer, "reserved:\n");
        list_for_each_entry(block, &bman->reserved, link)
-               i915_buddy_block_print(&bman->mm, block, printer);
+               drm_buddy_block_print(&bman->mm, block, printer);
        mutex_unlock(&bman->lock);
  }
@@ -190,7 +191,7 @@ int i915_ttm_buddy_man_init(struct ttm_device *bdev,
        if (!bman)
                return -ENOMEM;
- err = i915_buddy_init(&bman->mm, size, chunk_size);
+       err = drm_buddy_init(&bman->mm, size, chunk_size);
        if (err)
                goto err_free_bman;
@@ -228,7 +229,7 @@ int i915_ttm_buddy_man_fini(struct ttm_device *bdev, unsigned int type)
  {
        struct ttm_resource_manager *man = ttm_manager_type(bdev, type);
        struct i915_ttm_buddy_manager *bman = to_buddy_manager(man);
-       struct i915_buddy_mm *mm = &bman->mm;
+       struct drm_buddy_mm *mm = &bman->mm;
        int ret;
ttm_resource_manager_set_used(man, false);
@@ -240,8 +241,8 @@ int i915_ttm_buddy_man_fini(struct ttm_device *bdev, 
unsigned int type)
        ttm_set_driver_manager(bdev, type, NULL);
mutex_lock(&bman->lock);
-       i915_buddy_free_list(mm, &bman->reserved);
-       i915_buddy_fini(mm);
+       drm_buddy_free_list(mm, &bman->reserved);
+       drm_buddy_fini(mm);
        mutex_unlock(&bman->lock);
ttm_resource_manager_cleanup(man);
@@ -264,11 +265,11 @@ int i915_ttm_buddy_man_reserve(struct 
ttm_resource_manager *man,
                               u64 start, u64 size)
  {
        struct i915_ttm_buddy_manager *bman = to_buddy_manager(man);
-       struct i915_buddy_mm *mm = &bman->mm;
+       struct drm_buddy_mm *mm = &bman->mm;
        int ret;
mutex_lock(&bman->lock);
-       ret = i915_buddy_alloc_range(mm, &bman->reserved, start, size);
+       ret = drm_buddy_alloc_range(mm, &bman->reserved, start, size);
        mutex_unlock(&bman->lock);
return ret;
diff --git a/drivers/gpu/drm/i915/i915_ttm_buddy_manager.h 
b/drivers/gpu/drm/i915/i915_ttm_buddy_manager.h
index 0722d33f3e14..fa644b512c2e 100644
--- a/drivers/gpu/drm/i915/i915_ttm_buddy_manager.h
+++ b/drivers/gpu/drm/i915/i915_ttm_buddy_manager.h
@@ -13,7 +13,7 @@
struct ttm_device;
  struct ttm_resource_manager;
-struct i915_buddy_mm;
+struct drm_buddy_mm;
/**
   * struct i915_ttm_buddy_resource
@@ -28,7 +28,7 @@ struct i915_buddy_mm;
  struct i915_ttm_buddy_resource {
        struct ttm_resource base;
        struct list_head blocks;
-       struct i915_buddy_mm *mm;
+       struct drm_buddy_mm *mm;
  };
/**
diff --git a/include/drm/drm_buddy.h b/include/drm/drm_buddy.h
new file mode 100644
index 000000000000..5ce3fc702f80
--- /dev/null
+++ b/include/drm/drm_buddy.h
@@ -0,0 +1,153 @@
+/* SPDX-License-Identifier: MIT */
+/*
+ * Copyright © 2021 Intel Corporation
+ */
+
+#ifndef __DRM_BUDDY_H__
+#define __DRM_BUDDY_H__
+
+#include <linux/bitops.h>
+#include <linux/list.h>
+#include <linux/slab.h>
+#include <linux/sched.h>
+
+#include <drm/drm_print.h>
+
+#define range_overflows(start, size, max) ({ \
+       typeof(start) start__ = (start); \
+       typeof(size) size__ = (size); \
+       typeof(max) max__ = (max); \
+       (void)(&start__ == &size__); \
+       (void)(&start__ == &max__); \
+       start__ >= max__ || size__ > max__ - start__; \
+})
+
+struct drm_buddy_block {
+#define DRM_BUDDY_HEADER_OFFSET GENMASK_ULL(63, 12)
+#define DRM_BUDDY_HEADER_STATE  GENMASK_ULL(11, 10)
+#define   DRM_BUDDY_ALLOCATED     (1 << 10)
+#define   DRM_BUDDY_FREE          (2 << 10)
+#define   DRM_BUDDY_SPLIT         (3 << 10)
+/* Free to be used, if needed in the future */
+#define DRM_BUDDY_HEADER_UNUSED GENMASK_ULL(9, 6)
+#define DRM_BUDDY_HEADER_ORDER  GENMASK_ULL(5, 0)
+       u64 header;
+
+       struct drm_buddy_block *left;
+       struct drm_buddy_block *right;
+       struct drm_buddy_block *parent;
+
+       void *private; /* owned by creator */
+
+       /*
+        * While the block is allocated by the user through drm_buddy_alloc*,
+        * the user has ownership of the link, for example to maintain within
+        * a list, if so desired. As soon as the block is freed with
+        * drm_buddy_free* ownership is given back to the mm.
+        */
+       struct list_head link;
+       struct list_head tmp_link;
+};
+
+/* Order-zero must be at least PAGE_SIZE */
+#define DRM_BUDDY_MAX_ORDER (63 - PAGE_SHIFT)
+
+/*
+ * Binary Buddy System.
+ *
+ * Locking should be handled by the user, a simple mutex around
+ * drm_buddy_alloc* and drm_buddy_free* should suffice.
+ */
+struct drm_buddy_mm {
+       /* Maintain a free list for each order. */
+       struct list_head *free_list;
+
+       /*
+        * Maintain explicit binary tree(s) to track the allocation of the
+        * address space. This gives us a simple way of finding a buddy block
+        * and performing the potentially recursive merge step when freeing a
+        * block.  Nodes are either allocated or free, in which case they will
+        * also exist on the respective free list.
+        */
+       struct drm_buddy_block **roots;
+
+       /*
+        * Anything from here is public, and remains static for the lifetime of
+        * the mm. Everything above is considered do-not-touch.
+        */
+       unsigned int n_roots;
+       unsigned int max_order;
+
+       /* Must be at least PAGE_SIZE */
+       u64 chunk_size;
+       u64 size;
+       u64 avail;
+};
+
+static inline u64
+drm_buddy_block_offset(struct drm_buddy_block *block)
+{
+       return block->header & DRM_BUDDY_HEADER_OFFSET;
+}
+
+static inline unsigned int
+drm_buddy_block_order(struct drm_buddy_block *block)
+{
+       return block->header & DRM_BUDDY_HEADER_ORDER;
+}
+
+static inline unsigned int
+drm_buddy_block_state(struct drm_buddy_block *block)
+{
+       return block->header & DRM_BUDDY_HEADER_STATE;
+}
+
+static inline bool
+drm_buddy_block_is_allocated(struct drm_buddy_block *block)
+{
+       return drm_buddy_block_state(block) == DRM_BUDDY_ALLOCATED;
+}
+
+static inline bool
+drm_buddy_block_is_free(struct drm_buddy_block *block)
+{
+       return drm_buddy_block_state(block) == DRM_BUDDY_FREE;
+}
+
+static inline bool
+drm_buddy_block_is_split(struct drm_buddy_block *block)
+{
+       return drm_buddy_block_state(block) == DRM_BUDDY_SPLIT;
+}
+
+static inline u64
+drm_buddy_block_size(struct drm_buddy_mm *mm,
+                    struct drm_buddy_block *block)
+{
+       return mm->chunk_size << drm_buddy_block_order(block);
+}
+
+int drm_buddy_init(struct drm_buddy_mm *mm, u64 size, u64 chunk_size);
+
+void drm_buddy_fini(struct drm_buddy_mm *mm);
+
+struct drm_buddy_block *
+drm_buddy_alloc(struct drm_buddy_mm *mm, unsigned int order);
+
+int drm_buddy_alloc_range(struct drm_buddy_mm *mm,
+                         struct list_head *blocks,
+                         u64 start, u64 size);
+
+void drm_buddy_free(struct drm_buddy_mm *mm, struct drm_buddy_block *block);
+
+void drm_buddy_free_list(struct drm_buddy_mm *mm, struct list_head *objects);
+
+void drm_buddy_print(struct drm_buddy_mm *mm, struct drm_printer *p);
+void drm_buddy_block_print(struct drm_buddy_mm *mm,
+                          struct drm_buddy_block *block,
+                          struct drm_printer *p);
+
+void drm_buddy_module_exit(void);
+int drm_buddy_module_init(void);
+
+#endif

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