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/module.h> 14 #include <linux/genalloc.h> 15 16 17 /* 18 * Create a new special memory pool. 19 * 20 * @min_alloc_order: log base 2 of number of bytes each bitmap bit represents 21 * @nid: node id of the node the pool structure should be allocated on, or -1 22 */ 23 struct gen_pool *gen_pool_create(int min_alloc_order, int nid) 24 { 25 struct gen_pool *pool; 26 27 pool = kmalloc_node(sizeof(struct gen_pool), GFP_KERNEL, nid); 28 if (pool != NULL) { 29 rwlock_init(&pool->lock); 30 INIT_LIST_HEAD(&pool->chunks); 31 pool->min_alloc_order = min_alloc_order; 32 } 33 return pool; 34 } 35 EXPORT_SYMBOL(gen_pool_create); 36 37 38 /* 39 * Add a new chunk of memory to the specified pool. 40 * 41 * @pool: pool to add new memory chunk to 42 * @addr: starting address of memory chunk to add to pool 43 * @size: size in bytes of the memory chunk to add to pool 44 * @nid: node id of the node the chunk structure and bitmap should be 45 * allocated on, or -1 46 */ 47 int gen_pool_add(struct gen_pool *pool, unsigned long addr, size_t size, 48 int nid) 49 { 50 struct gen_pool_chunk *chunk; 51 int nbits = size >> pool->min_alloc_order; 52 int nbytes = sizeof(struct gen_pool_chunk) + 53 (nbits + BITS_PER_BYTE - 1) / BITS_PER_BYTE; 54 55 chunk = kmalloc_node(nbytes, GFP_KERNEL, nid); 56 if (unlikely(chunk == NULL)) 57 return -1; 58 59 memset(chunk, 0, nbytes); 60 spin_lock_init(&chunk->lock); 61 chunk->start_addr = addr; 62 chunk->end_addr = addr + size; 63 64 write_lock(&pool->lock); 65 list_add(&chunk->next_chunk, &pool->chunks); 66 write_unlock(&pool->lock); 67 68 return 0; 69 } 70 EXPORT_SYMBOL(gen_pool_add); 71 72 73 /* 74 * Allocate the requested number of bytes from the specified pool. 75 * Uses a first-fit algorithm. 76 * 77 * @pool: pool to allocate from 78 * @size: number of bytes to allocate from the pool 79 */ 80 unsigned long gen_pool_alloc(struct gen_pool *pool, size_t size) 81 { 82 struct list_head *_chunk; 83 struct gen_pool_chunk *chunk; 84 unsigned long addr, flags; 85 int order = pool->min_alloc_order; 86 int nbits, bit, start_bit, end_bit; 87 88 if (size == 0) 89 return 0; 90 91 nbits = (size + (1UL << order) - 1) >> order; 92 93 read_lock(&pool->lock); 94 list_for_each(_chunk, &pool->chunks) { 95 chunk = list_entry(_chunk, struct gen_pool_chunk, next_chunk); 96 97 end_bit = (chunk->end_addr - chunk->start_addr) >> order; 98 end_bit -= nbits + 1; 99 100 spin_lock_irqsave(&chunk->lock, flags); 101 bit = -1; 102 while (bit + 1 < end_bit) { 103 bit = find_next_zero_bit(chunk->bits, end_bit, bit + 1); 104 if (bit >= end_bit) 105 break; 106 107 start_bit = bit; 108 if (nbits > 1) { 109 bit = find_next_bit(chunk->bits, bit + nbits, 110 bit + 1); 111 if (bit - start_bit < nbits) 112 continue; 113 } 114 115 addr = chunk->start_addr + 116 ((unsigned long)start_bit << order); 117 while (nbits--) 118 __set_bit(start_bit++, &chunk->bits); 119 spin_unlock_irqrestore(&chunk->lock, flags); 120 read_unlock(&pool->lock); 121 return addr; 122 } 123 spin_unlock_irqrestore(&chunk->lock, flags); 124 } 125 read_unlock(&pool->lock); 126 return 0; 127 } 128 EXPORT_SYMBOL(gen_pool_alloc); 129 130 131 /* 132 * Free the specified memory back to the specified pool. 133 * 134 * @pool: pool to free to 135 * @addr: starting address of memory to free back to pool 136 * @size: size in bytes of memory to free 137 */ 138 void gen_pool_free(struct gen_pool *pool, unsigned long addr, size_t size) 139 { 140 struct list_head *_chunk; 141 struct gen_pool_chunk *chunk; 142 unsigned long flags; 143 int order = pool->min_alloc_order; 144 int bit, nbits; 145 146 nbits = (size + (1UL << order) - 1) >> order; 147 148 read_lock(&pool->lock); 149 list_for_each(_chunk, &pool->chunks) { 150 chunk = list_entry(_chunk, struct gen_pool_chunk, next_chunk); 151 152 if (addr >= chunk->start_addr && addr < chunk->end_addr) { 153 BUG_ON(addr + size > chunk->end_addr); 154 spin_lock_irqsave(&chunk->lock, flags); 155 bit = (addr - chunk->start_addr) >> order; 156 while (nbits--) 157 __clear_bit(bit++, &chunk->bits); 158 spin_unlock_irqrestore(&chunk->lock, flags); 159 break; 160 } 161 } 162 BUG_ON(nbits > 0); 163 read_unlock(&pool->lock); 164 } 165 EXPORT_SYMBOL(gen_pool_free); 166