lib/genalloc.c

   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 <jes@trained-monkey.org>
   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  */
  27 struct 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 }
  39 EXPORT_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  */
  54 int 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 }
  77 EXPORT_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  */
  86 phys_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 }
 102 EXPORT_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  */
 111 void 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 }
 132 EXPORT_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  */
 142 unsigned 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 }
 179 EXPORT_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  */
 189 void 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 }
 216 EXPORT_SYMBOL(gen_pool_free);