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/* 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_ALLOCATED (1 << 10)
#define I915_BUDDY_FREE (2 << 10)
#define I915_BUDDY_SPLIT (3 << 10)
/* Free to be used, if needed in the future */
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);