1/* SPDX-License-Identifier: MIT */
  2/*
  3 * Copyright © 2021 Intel Corporation
  4 */
  5
  6#ifndef __DRM_BUDDY_H__
  7#define __DRM_BUDDY_H__
  8
  9#include <linux/bitops.h>
 10#include <linux/list.h>
 11#include <linux/slab.h>
 12#include <linux/sched.h>
 13
 14#include <drm/drm_print.h>
 15
 16#define range_overflows(start, size, max) ({ \
 17	typeof(start) start__ = (start); \
 18	typeof(size) size__ = (size); \
 19	typeof(max) max__ = (max); \
 20	(void)(&start__ == &size__); \
 21	(void)(&start__ == &max__); \
 22	start__ >= max__ || size__ > max__ - start__; \
 23})
 24
 25#define DRM_BUDDY_RANGE_ALLOCATION (1 << 0)
 26#define DRM_BUDDY_TOPDOWN_ALLOCATION (1 << 1)
 27
 28struct drm_buddy_block {
 29#define DRM_BUDDY_HEADER_OFFSET GENMASK_ULL(63, 12)
 30#define DRM_BUDDY_HEADER_STATE  GENMASK_ULL(11, 10)
 31#define   DRM_BUDDY_ALLOCATED	   (1 << 10)
 32#define   DRM_BUDDY_FREE	   (2 << 10)
 33#define   DRM_BUDDY_SPLIT	   (3 << 10)
 34/* Free to be used, if needed in the future */
 35#define DRM_BUDDY_HEADER_UNUSED GENMASK_ULL(9, 6)
 36#define DRM_BUDDY_HEADER_ORDER  GENMASK_ULL(5, 0)
 37	u64 header;
 38
 39	struct drm_buddy_block *left;
 40	struct drm_buddy_block *right;
 41	struct drm_buddy_block *parent;
 42
 43	void *private; /* owned by creator */
 44
 45	/*
 46	 * While the block is allocated by the user through drm_buddy_alloc*,
 47	 * the user has ownership of the link, for example to maintain within
 48	 * a list, if so desired. As soon as the block is freed with
 49	 * drm_buddy_free* ownership is given back to the mm.
 50	 */
 51	struct list_head link;
 52	struct list_head tmp_link;
 53};
 54
 55/* Order-zero must be at least PAGE_SIZE */
 56#define DRM_BUDDY_MAX_ORDER (63 - PAGE_SHIFT)
 57
 58/*
 59 * Binary Buddy System.
 60 *
 61 * Locking should be handled by the user, a simple mutex around
 62 * drm_buddy_alloc* and drm_buddy_free* should suffice.
 63 */
 64struct drm_buddy {
 65	/* Maintain a free list for each order. */
 66	struct list_head *free_list;
 67
 68	/*
 69	 * Maintain explicit binary tree(s) to track the allocation of the
 70	 * address space. This gives us a simple way of finding a buddy block
 71	 * and performing the potentially recursive merge step when freeing a
 72	 * block.  Nodes are either allocated or free, in which case they will
 73	 * also exist on the respective free list.
 74	 */
 75	struct drm_buddy_block **roots;
 76
 77	/*
 78	 * Anything from here is public, and remains static for the lifetime of
 79	 * the mm. Everything above is considered do-not-touch.
 80	 */
 81	unsigned int n_roots;
 82	unsigned int max_order;
 83
 84	/* Must be at least PAGE_SIZE */
 85	u64 chunk_size;
 86	u64 size;
 87	u64 avail;
 88};
 89
 90static inline u64
 91drm_buddy_block_offset(struct drm_buddy_block *block)
 92{
 93	return block->header & DRM_BUDDY_HEADER_OFFSET;
 94}
 95
 96static inline unsigned int
 97drm_buddy_block_order(struct drm_buddy_block *block)
 98{
 99	return block->header & DRM_BUDDY_HEADER_ORDER;
100}
101
102static inline unsigned int
103drm_buddy_block_state(struct drm_buddy_block *block)
104{
105	return block->header & DRM_BUDDY_HEADER_STATE;
106}
107
108static inline bool
109drm_buddy_block_is_allocated(struct drm_buddy_block *block)
110{
111	return drm_buddy_block_state(block) == DRM_BUDDY_ALLOCATED;
112}
113
114static inline bool
115drm_buddy_block_is_free(struct drm_buddy_block *block)
116{
117	return drm_buddy_block_state(block) == DRM_BUDDY_FREE;
118}
119
120static inline bool
121drm_buddy_block_is_split(struct drm_buddy_block *block)
122{
123	return drm_buddy_block_state(block) == DRM_BUDDY_SPLIT;
124}
125
126static inline u64
127drm_buddy_block_size(struct drm_buddy *mm,
128		     struct drm_buddy_block *block)
129{
130	return mm->chunk_size << drm_buddy_block_order(block);
131}
132
133int drm_buddy_init(struct drm_buddy *mm, u64 size, u64 chunk_size);
134
135void drm_buddy_fini(struct drm_buddy *mm);
136
137struct drm_buddy_block *
138drm_get_buddy(struct drm_buddy_block *block);
139
140int drm_buddy_alloc_blocks(struct drm_buddy *mm,
141			   u64 start, u64 end, u64 size,
142			   u64 min_page_size,
143			   struct list_head *blocks,
144			   unsigned long flags);
145
146int drm_buddy_block_trim(struct drm_buddy *mm,
147			 u64 new_size,
148			 struct list_head *blocks);
149
150void drm_buddy_free_block(struct drm_buddy *mm, struct drm_buddy_block *block);
151
152void drm_buddy_free_list(struct drm_buddy *mm, struct list_head *objects);
153
154void drm_buddy_print(struct drm_buddy *mm, struct drm_printer *p);
155void drm_buddy_block_print(struct drm_buddy *mm,
156			   struct drm_buddy_block *block,
157			   struct drm_printer *p);
158
159#endif