diff options
Diffstat (limited to 'lib/genalloc.c')
-rw-r--r-- | lib/genalloc.c | 216 |
1 files changed, 216 insertions, 0 deletions
diff --git a/lib/genalloc.c b/lib/genalloc.c new file mode 100644 index 00000000..577ddf80 --- /dev/null +++ b/lib/genalloc.c @@ -0,0 +1,216 @@ +/* + * Basic general purpose allocator for managing special purpose memory + * not managed by the regular kmalloc/kfree interface. + * Uses for this includes on-device special memory, uncached memory + * etc. + * + * Copyright 2005 (C) Jes Sorensen <jes@trained-monkey.org> + * + * This source code is licensed under the GNU General Public License, + * Version 2. See the file COPYING for more details. + */ + +#include <linux/slab.h> +#include <linux/module.h> +#include <linux/bitmap.h> +#include <linux/genalloc.h> + + +/** + * gen_pool_create - create a new special memory pool + * @min_alloc_order: log base 2 of number of bytes each bitmap bit represents + * @nid: node id of the node the pool structure should be allocated on, or -1 + * + * Create a new special memory pool that can be used to manage special purpose + * memory not managed by the regular kmalloc/kfree interface. + */ +struct gen_pool *gen_pool_create(int min_alloc_order, int nid) +{ + struct gen_pool *pool; + + pool = kmalloc_node(sizeof(struct gen_pool), GFP_KERNEL, nid); + if (pool != NULL) { + rwlock_init(&pool->lock); + INIT_LIST_HEAD(&pool->chunks); + pool->min_alloc_order = min_alloc_order; + } + return pool; +} +EXPORT_SYMBOL(gen_pool_create); + +/** + * gen_pool_add_virt - add a new chunk of special memory to the pool + * @pool: pool to add new memory chunk to + * @virt: virtual starting address of memory chunk to add to pool + * @phys: physical starting address of memory chunk to add to pool + * @size: size in bytes of the memory chunk to add to pool + * @nid: node id of the node the chunk structure and bitmap should be + * allocated on, or -1 + * + * Add a new chunk of special memory to the specified pool. + * + * Returns 0 on success or a -ve errno on failure. + */ +int gen_pool_add_virt(struct gen_pool *pool, unsigned long virt, phys_addr_t phys, + size_t size, int nid) +{ + struct gen_pool_chunk *chunk; + int nbits = size >> pool->min_alloc_order; + int nbytes = sizeof(struct gen_pool_chunk) + + (nbits + BITS_PER_BYTE - 1) / BITS_PER_BYTE; + + chunk = kmalloc_node(nbytes, GFP_KERNEL | __GFP_ZERO, nid); + if (unlikely(chunk == NULL)) + return -ENOMEM; + + spin_lock_init(&chunk->lock); + chunk->phys_addr = phys; + chunk->start_addr = virt; + chunk->end_addr = virt + size; + + write_lock(&pool->lock); + list_add(&chunk->next_chunk, &pool->chunks); + write_unlock(&pool->lock); + + return 0; +} +EXPORT_SYMBOL(gen_pool_add_virt); + +/** + * gen_pool_virt_to_phys - return the physical address of memory + * @pool: pool to allocate from + * @addr: starting address of memory + * + * Returns the physical address on success, or -1 on error. + */ +phys_addr_t gen_pool_virt_to_phys(struct gen_pool *pool, unsigned long addr) +{ + struct list_head *_chunk; + struct gen_pool_chunk *chunk; + + read_lock(&pool->lock); + list_for_each(_chunk, &pool->chunks) { + chunk = list_entry(_chunk, struct gen_pool_chunk, next_chunk); + + if (addr >= chunk->start_addr && addr < chunk->end_addr) + return chunk->phys_addr + addr - chunk->start_addr; + } + read_unlock(&pool->lock); + + return -1; +} +EXPORT_SYMBOL(gen_pool_virt_to_phys); + +/** + * gen_pool_destroy - destroy a special memory pool + * @pool: pool to destroy + * + * Destroy the specified special memory pool. Verifies that there are no + * outstanding allocations. + */ +void gen_pool_destroy(struct gen_pool *pool) +{ + struct list_head *_chunk, *_next_chunk; + struct gen_pool_chunk *chunk; + int order = pool->min_alloc_order; + int bit, end_bit; + + + list_for_each_safe(_chunk, _next_chunk, &pool->chunks) { + chunk = list_entry(_chunk, struct gen_pool_chunk, next_chunk); + list_del(&chunk->next_chunk); + + end_bit = (chunk->end_addr - chunk->start_addr) >> order; + bit = find_next_bit(chunk->bits, end_bit, 0); + BUG_ON(bit < end_bit); + + kfree(chunk); + } + kfree(pool); + return; +} +EXPORT_SYMBOL(gen_pool_destroy); + +/** + * gen_pool_alloc - allocate special memory from the pool + * @pool: pool to allocate from + * @size: number of bytes to allocate from the pool + * + * Allocate the requested number of bytes from the specified pool. + * Uses a first-fit algorithm. + */ +unsigned long gen_pool_alloc(struct gen_pool *pool, size_t size) +{ + struct list_head *_chunk; + struct gen_pool_chunk *chunk; + unsigned long addr, flags; + int order = pool->min_alloc_order; + int nbits, start_bit, end_bit; + + if (size == 0) + return 0; + + nbits = (size + (1UL << order) - 1) >> order; + + read_lock(&pool->lock); + list_for_each(_chunk, &pool->chunks) { + chunk = list_entry(_chunk, struct gen_pool_chunk, next_chunk); + + end_bit = (chunk->end_addr - chunk->start_addr) >> order; + + spin_lock_irqsave(&chunk->lock, flags); + start_bit = bitmap_find_next_zero_area(chunk->bits, end_bit, 0, + nbits, 0); + if (start_bit >= end_bit) { + spin_unlock_irqrestore(&chunk->lock, flags); + continue; + } + + addr = chunk->start_addr + ((unsigned long)start_bit << order); + + bitmap_set(chunk->bits, start_bit, nbits); + spin_unlock_irqrestore(&chunk->lock, flags); + read_unlock(&pool->lock); + return addr; + } + read_unlock(&pool->lock); + return 0; +} +EXPORT_SYMBOL(gen_pool_alloc); + +/** + * gen_pool_free - free allocated special memory back to the pool + * @pool: pool to free to + * @addr: starting address of memory to free back to pool + * @size: size in bytes of memory to free + * + * Free previously allocated special memory back to the specified pool. + */ +void gen_pool_free(struct gen_pool *pool, unsigned long addr, size_t size) +{ + struct list_head *_chunk; + struct gen_pool_chunk *chunk; + unsigned long flags; + int order = pool->min_alloc_order; + int bit, nbits; + + nbits = (size + (1UL << order) - 1) >> order; + + read_lock(&pool->lock); + list_for_each(_chunk, &pool->chunks) { + chunk = list_entry(_chunk, struct gen_pool_chunk, next_chunk); + + if (addr >= chunk->start_addr && addr < chunk->end_addr) { + BUG_ON(addr + size > chunk->end_addr); + spin_lock_irqsave(&chunk->lock, flags); + bit = (addr - chunk->start_addr) >> order; + while (nbits--) + __clear_bit(bit++, chunk->bits); + spin_unlock_irqrestore(&chunk->lock, flags); + break; + } + } + BUG_ON(nbits > 0); + read_unlock(&pool->lock); +} +EXPORT_SYMBOL(gen_pool_free); |