/* * 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/module.h>#include <linux/genalloc.h>  /* * 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 */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);  /* * Add a new chunk of memory to the specified pool. * * @pool: pool to add new memory chunk to * @addr: 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 */int gen_pool_add(struct gen_pool *pool, unsigned long addr, 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, nid);	if (unlikely(chunk == NULL))		return -1; 	memset(chunk, 0, nbytes);	spin_lock_init(&chunk->lock);	chunk->start_addr = addr;	chunk->end_addr = addr + size; 	write_lock(&pool->lock);	list_add(&chunk->next_chunk, &pool->chunks);	write_unlock(&pool->lock); 	return 0;}EXPORT_SYMBOL(gen_pool_add);  /* * Allocate the requested number of bytes from the specified pool. * Uses a first-fit algorithm. * * @pool: pool to allocate from * @size: number of bytes to allocate from the pool */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, bit, 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;		end_bit -= nbits + 1; 		spin_lock_irqsave(&chunk->lock, flags);		bit = -1;		while (bit + 1 < end_bit) {			bit = find_next_zero_bit(chunk->bits, end_bit, bit + 1);			if (bit >= end_bit)				break; 			start_bit = bit;			if (nbits > 1) {				bit = find_next_bit(chunk->bits, bit + nbits,							bit + 1);				if (bit - start_bit < nbits)					continue;			} 			addr = chunk->start_addr +					    ((unsigned long)start_bit << order);			while (nbits--)				__set_bit(start_bit++, &chunk->bits);			spin_unlock_irqrestore(&chunk->lock, flags);			read_unlock(&pool->lock);			return addr;		}		spin_unlock_irqrestore(&chunk->lock, flags);	}	read_unlock(&pool->lock);	return 0;}EXPORT_SYMBOL(gen_pool_alloc);  /* * Free the specified memory back to the specified pool. * * @pool: pool to free to * @addr: starting address of memory to free back to pool * @size: size in bytes of memory to free */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);