projects/linux·blob v3.0 · refs

216 lines · 5.9 KiB

1/*
2 * Basic general purpose allocator for managing special purpose memory
3 * not managed by the regular kmalloc/kfree interface.
4 * Uses for this includes on-device special memory, uncached memory
5 * etc.
6 *
7 * Copyright 2005 (C) Jes Sorensen <[email protected]>
8 *
9 * This source code is licensed under the GNU General Public License,
10 * Version 2. See the file COPYING for more details.
11 */
12
13#include <linux/slab.h>
14#include <linux/module.h>
15#include <linux/bitmap.h>
16#include <linux/genalloc.h>
17
18
19/**
20 * gen_pool_create - create a new special memory pool
21 * @min_alloc_order: log base 2 of number of bytes each bitmap bit represents
22 * @nid: node id of the node the pool structure should be allocated on, or -1
23 *
24 * Create a new special memory pool that can be used to manage special purpose
25 * memory not managed by the regular kmalloc/kfree interface.
26 */
27struct gen_pool *gen_pool_create(int min_alloc_order, int nid)
28{
29 struct gen_pool *pool;
30
31 pool = kmalloc_node(sizeof(struct gen_pool), GFP_KERNEL, nid);
32 if (pool != NULL) {
33 rwlock_init(&pool->lock);
34 INIT_LIST_HEAD(&pool->chunks);
35 pool->min_alloc_order = min_alloc_order;
36 }
37 return pool;
38}
39EXPORT_SYMBOL(gen_pool_create);
40
41/**
42 * gen_pool_add_virt - add a new chunk of special memory to the pool
43 * @pool: pool to add new memory chunk to
44 * @virt: virtual starting address of memory chunk to add to pool
45 * @phys: physical starting address of memory chunk to add to pool
46 * @size: size in bytes of the memory chunk to add to pool
47 * @nid: node id of the node the chunk structure and bitmap should be
48 * allocated on, or -1
49 *
50 * Add a new chunk of special memory to the specified pool.
51 *
52 * Returns 0 on success or a -ve errno on failure.
53 */
54int gen_pool_add_virt(struct gen_pool *pool, unsigned long virt, phys_addr_t phys,
55 size_t size, int nid)
56{
57 struct gen_pool_chunk *chunk;
58 int nbits = size >> pool->min_alloc_order;
59 int nbytes = sizeof(struct gen_pool_chunk) +
60 (nbits + BITS_PER_BYTE - 1) / BITS_PER_BYTE;
61
62 chunk = kmalloc_node(nbytes, GFP_KERNEL | __GFP_ZERO, nid);
63 if (unlikely(chunk == NULL))
64 return -ENOMEM;
65
66 spin_lock_init(&chunk->lock);
67 chunk->phys_addr = phys;
68 chunk->start_addr = virt;
69 chunk->end_addr = virt + size;
70
71 write_lock(&pool->lock);
72 list_add(&chunk->next_chunk, &pool->chunks);
73 write_unlock(&pool->lock);
74
75 return 0;
76}
77EXPORT_SYMBOL(gen_pool_add_virt);
78
79/**
80 * gen_pool_virt_to_phys - return the physical address of memory
81 * @pool: pool to allocate from
82 * @addr: starting address of memory
83 *
84 * Returns the physical address on success, or -1 on error.
85 */
86phys_addr_t gen_pool_virt_to_phys(struct gen_pool *pool, unsigned long addr)
87{
88 struct list_head *_chunk;
89 struct gen_pool_chunk *chunk;
90
91 read_lock(&pool->lock);
92 list_for_each(_chunk, &pool->chunks) {
93 chunk = list_entry(_chunk, struct gen_pool_chunk, next_chunk);
94
95 if (addr >= chunk->start_addr && addr < chunk->end_addr)
96 return chunk->phys_addr + addr - chunk->start_addr;
97 }
98 read_unlock(&pool->lock);
99
100 return -1;
101}
102EXPORT_SYMBOL(gen_pool_virt_to_phys);
103
104/**
105 * gen_pool_destroy - destroy a special memory pool
106 * @pool: pool to destroy
107 *
108 * Destroy the specified special memory pool. Verifies that there are no
109 * outstanding allocations.
110 */
111void gen_pool_destroy(struct gen_pool *pool)
112{
113 struct list_head *_chunk, *_next_chunk;
114 struct gen_pool_chunk *chunk;
115 int order = pool->min_alloc_order;
116 int bit, end_bit;
117
118
119 list_for_each_safe(_chunk, _next_chunk, &pool->chunks) {
120 chunk = list_entry(_chunk, struct gen_pool_chunk, next_chunk);
121 list_del(&chunk->next_chunk);
122
123 end_bit = (chunk->end_addr - chunk->start_addr) >> order;
124 bit = find_next_bit(chunk->bits, end_bit, 0);
125 BUG_ON(bit < end_bit);
126
127 kfree(chunk);
128 }
129 kfree(pool);
130 return;
131}
132EXPORT_SYMBOL(gen_pool_destroy);
133
134/**
135 * gen_pool_alloc - allocate special memory from the pool
136 * @pool: pool to allocate from
137 * @size: number of bytes to allocate from the pool
138 *
139 * Allocate the requested number of bytes from the specified pool.
140 * Uses a first-fit algorithm.
141 */
142unsigned long gen_pool_alloc(struct gen_pool *pool, size_t size)
143{
144 struct list_head *_chunk;
145 struct gen_pool_chunk *chunk;
146 unsigned long addr, flags;
147 int order = pool->min_alloc_order;
148 int nbits, start_bit, end_bit;
149
150 if (size == 0)
151 return 0;
152
153 nbits = (size + (1UL << order) - 1) >> order;
154
155 read_lock(&pool->lock);
156 list_for_each(_chunk, &pool->chunks) {
157 chunk = list_entry(_chunk, struct gen_pool_chunk, next_chunk);
158
159 end_bit = (chunk->end_addr - chunk->start_addr) >> order;
160
161 spin_lock_irqsave(&chunk->lock, flags);
162 start_bit = bitmap_find_next_zero_area(chunk->bits, end_bit, 0,
163 nbits, 0);
164 if (start_bit >= end_bit) {
165 spin_unlock_irqrestore(&chunk->lock, flags);
166 continue;
167 }
168
169 addr = chunk->start_addr + ((unsigned long)start_bit << order);
170
171 bitmap_set(chunk->bits, start_bit, nbits);
172 spin_unlock_irqrestore(&chunk->lock, flags);
173 read_unlock(&pool->lock);
174 return addr;
175 }
176 read_unlock(&pool->lock);
177 return 0;
178}
179EXPORT_SYMBOL(gen_pool_alloc);
180
181/**
182 * gen_pool_free - free allocated special memory back to the pool
183 * @pool: pool to free to
184 * @addr: starting address of memory to free back to pool
185 * @size: size in bytes of memory to free
186 *
187 * Free previously allocated special memory back to the specified pool.
188 */
189void gen_pool_free(struct gen_pool *pool, unsigned long addr, size_t size)
190{
191 struct list_head *_chunk;
192 struct gen_pool_chunk *chunk;
193 unsigned long flags;
194 int order = pool->min_alloc_order;
195 int bit, nbits;
196
197 nbits = (size + (1UL << order) - 1) >> order;
198
199 read_lock(&pool->lock);
200 list_for_each(_chunk, &pool->chunks) {
201 chunk = list_entry(_chunk, struct gen_pool_chunk, next_chunk);
202
203 if (addr >= chunk->start_addr && addr < chunk->end_addr) {
204 BUG_ON(addr + size > chunk->end_addr);
205 spin_lock_irqsave(&chunk->lock, flags);
206 bit = (addr - chunk->start_addr) >> order;
207 while (nbits--)
208 __clear_bit(bit++, chunk->bits);
209 spin_unlock_irqrestore(&chunk->lock, flags);
210 break;
211 }
212 }
213 BUG_ON(nbits > 0);
214 read_unlock(&pool->lock);
215}
216EXPORT_SYMBOL(gen_pool_free);