1/* SPDX-License-Identifier: MIT */
2/*
3 * Copyright © 2019 Intel Corporation
4 */
5
6#ifndef __I915_BUDDY_H__
7#define __I915_BUDDY_H__
8
9#include <linux/bitops.h>
10#include <linux/list.h>
11
12struct i915_buddy_block {
13#define I915_BUDDY_HEADER_OFFSET GENMASK_ULL(63, 12)
14#define I915_BUDDY_HEADER_STATE  GENMASK_ULL(11, 10)
15#define   I915_BUDDY_ALLOCATED	   (1 << 10)
16#define   I915_BUDDY_FREE	   (2 << 10)
17#define   I915_BUDDY_SPLIT	   (3 << 10)
18#define I915_BUDDY_HEADER_ORDER  GENMASK_ULL(9, 0)
19	u64 header;
20
21	struct i915_buddy_block *left;
22	struct i915_buddy_block *right;
23	struct i915_buddy_block *parent;
24
25	void *private; /* owned by creator */
26
27	/*
28	 * While the block is allocated by the user through i915_buddy_alloc*,
29	 * the user has ownership of the link, for example to maintain within
30	 * a list, if so desired. As soon as the block is freed with
31	 * i915_buddy_free* ownership is given back to the mm.
32	 */
33	struct list_head link;
34	struct list_head tmp_link;
35};
36
37#define I915_BUDDY_MAX_ORDER  I915_BUDDY_HEADER_ORDER
38
39/*
40 * Binary Buddy System.
41 *
42 * Locking should be handled by the user, a simple mutex around
43 * i915_buddy_alloc* and i915_buddy_free* should suffice.
44 */
45struct i915_buddy_mm {
46	/* Maintain a free list for each order. */
47	struct list_head *free_list;
48
49	/*
50	 * Maintain explicit binary tree(s) to track the allocation of the
51	 * address space. This gives us a simple way of finding a buddy block
52	 * and performing the potentially recursive merge step when freeing a
53	 * block.  Nodes are either allocated or free, in which case they will
54	 * also exist on the respective free list.
55	 */
56	struct i915_buddy_block **roots;
57
58	/*
59	 * Anything from here is public, and remains static for the lifetime of
60	 * the mm. Everything above is considered do-not-touch.
61	 */
62	unsigned int n_roots;
63	unsigned int max_order;
64
65	/* Must be at least PAGE_SIZE */
66	u64 chunk_size;
67	u64 size;
68};
69
70static inline u64
71i915_buddy_block_offset(struct i915_buddy_block *block)
72{
73	return block->header & I915_BUDDY_HEADER_OFFSET;
74}
75
76static inline unsigned int
77i915_buddy_block_order(struct i915_buddy_block *block)
78{
79	return block->header & I915_BUDDY_HEADER_ORDER;
80}
81
82static inline unsigned int
83i915_buddy_block_state(struct i915_buddy_block *block)
84{
85	return block->header & I915_BUDDY_HEADER_STATE;
86}
87
88static inline bool
89i915_buddy_block_is_allocated(struct i915_buddy_block *block)
90{
91	return i915_buddy_block_state(block) == I915_BUDDY_ALLOCATED;
92}
93
94static inline bool
95i915_buddy_block_is_free(struct i915_buddy_block *block)
96{
97	return i915_buddy_block_state(block) == I915_BUDDY_FREE;
98}
99
100static inline bool
101i915_buddy_block_is_split(struct i915_buddy_block *block)
102{
103	return i915_buddy_block_state(block) == I915_BUDDY_SPLIT;
104}
105
106static inline u64
107i915_buddy_block_size(struct i915_buddy_mm *mm,
108		      struct i915_buddy_block *block)
109{
110	return mm->chunk_size << i915_buddy_block_order(block);
111}
112
113int i915_buddy_init(struct i915_buddy_mm *mm, u64 size, u64 chunk_size);
114
115void i915_buddy_fini(struct i915_buddy_mm *mm);
116
117struct i915_buddy_block *
118i915_buddy_alloc(struct i915_buddy_mm *mm, unsigned int order);
119
120int i915_buddy_alloc_range(struct i915_buddy_mm *mm,
121			   struct list_head *blocks,
122			   u64 start, u64 size);
123
124void i915_buddy_free(struct i915_buddy_mm *mm, struct i915_buddy_block *block);
125
126void i915_buddy_free_list(struct i915_buddy_mm *mm, struct list_head *objects);
127
128#endif
129