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