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/*

 * 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>

/**

 * 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 - add a new chunk of special memory to the 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

 *

 * Add a new chunk of special memory to the specified pool.

 */

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 | __GFP_ZERO, nid);

        if (unlikely(chunk == NULL))

                return -1;

        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);

/**

 * 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;

        write_lock(&pool->lock);

        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, 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);

/**

 * 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);