Merge tag 'acpi-5.12-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael...

[thirdparty/kernel/linux.git] / lib / genalloc.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Basic general purpose allocator for managing special purpose
 * memory, for example, memory that is not managed by the regular
 * kmalloc/kfree interface.  Uses for this includes on-device special
 * memory, uncached memory etc.
 *
 * It is safe to use the allocator in NMI handlers and other special
 * unblockable contexts that could otherwise deadlock on locks.  This
 * is implemented by using atomic operations and retries on any
 * conflicts.  The disadvantage is that there may be livelocks in
 * extreme cases.  For better scalability, one allocator can be used
 * for each CPU.
 *
 * The lockless operation only works if there is enough memory
 * available.  If new memory is added to the pool a lock has to be
 * still taken.  So any user relying on locklessness has to ensure
 * that sufficient memory is preallocated.
 *
 * The basic atomic operation of this allocator is cmpxchg on long.
 * On architectures that don't have NMI-safe cmpxchg implementation,
 * the allocator can NOT be used in NMI handler.  So code uses the
 * allocator in NMI handler should depend on
 * CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG.
 *
 * Copyright 2005 (C) Jes Sorensen <jes@trained-monkey.org>
 */

#include <linux/slab.h>
#include <linux/export.h>
#include <linux/bitmap.h>
#include <linux/rculist.h>
#include <linux/interrupt.h>
#include <linux/genalloc.h>
#include <linux/of_device.h>
#include <linux/vmalloc.h>

static inline size_t chunk_size(const struct gen_pool_chunk *chunk)
{
        return chunk->end_addr - chunk->start_addr + 1;
}

static int set_bits_ll(unsigned long *addr, unsigned long mask_to_set)
{
        unsigned long val, nval;

        nval = *addr;
        do {
                val = nval;
                if (val & mask_to_set)
                        return -EBUSY;
                cpu_relax();
        } while ((nval = cmpxchg(addr, val, val | mask_to_set)) != val);

        return 0;
}

static int clear_bits_ll(unsigned long *addr, unsigned long mask_to_clear)
{
        unsigned long val, nval;

        nval = *addr;
        do {
                val = nval;
                if ((val & mask_to_clear) != mask_to_clear)
                        return -EBUSY;
                cpu_relax();
        } while ((nval = cmpxchg(addr, val, val & ~mask_to_clear)) != val);

        return 0;
}

/*
 * bitmap_set_ll - set the specified number of bits at the specified position
 * @map: pointer to a bitmap
 * @start: a bit position in @map
 * @nr: number of bits to set
 *
 * Set @nr bits start from @start in @map lock-lessly. Several users
 * can set/clear the same bitmap simultaneously without lock. If two
 * users set the same bit, one user will return remain bits, otherwise
 * return 0.
 */
static unsigned long
bitmap_set_ll(unsigned long *map, unsigned long start, unsigned long nr)
{
        unsigned long *p = map + BIT_WORD(start);
        const unsigned long size = start + nr;
        int bits_to_set = BITS_PER_LONG - (start % BITS_PER_LONG);
        unsigned long mask_to_set = BITMAP_FIRST_WORD_MASK(start);

        while (nr >= bits_to_set) {
                if (set_bits_ll(p, mask_to_set))
                        return nr;
                nr -= bits_to_set;
                bits_to_set = BITS_PER_LONG;
                mask_to_set = ~0UL;
                p++;
        }
        if (nr) {
                mask_to_set &= BITMAP_LAST_WORD_MASK(size);
                if (set_bits_ll(p, mask_to_set))
                        return nr;
        }

        return 0;
}

/*
 * bitmap_clear_ll - clear the specified number of bits at the specified position
 * @map: pointer to a bitmap
 * @start: a bit position in @map
 * @nr: number of bits to set
 *
 * Clear @nr bits start from @start in @map lock-lessly. Several users
 * can set/clear the same bitmap simultaneously without lock. If two
 * users clear the same bit, one user will return remain bits,
 * otherwise return 0.
 */
static unsigned long
bitmap_clear_ll(unsigned long *map, unsigned long start, unsigned long nr)
{
        unsigned long *p = map + BIT_WORD(start);
        const unsigned long size = start + nr;
        int bits_to_clear = BITS_PER_LONG - (start % BITS_PER_LONG);
        unsigned long mask_to_clear = BITMAP_FIRST_WORD_MASK(start);

        while (nr >= bits_to_clear) {
                if (clear_bits_ll(p, mask_to_clear))
                        return nr;
                nr -= bits_to_clear;
                bits_to_clear = BITS_PER_LONG;
                mask_to_clear = ~0UL;
                p++;
        }
        if (nr) {
                mask_to_clear &= BITMAP_LAST_WORD_MASK(size);
                if (clear_bits_ll(p, mask_to_clear))
                        return nr;
        }

        return 0;
}

/**
 * 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) {
                spin_lock_init(&pool->lock);
                INIT_LIST_HEAD(&pool->chunks);
                pool->min_alloc_order = min_alloc_order;
                pool->algo = gen_pool_first_fit;
                pool->data = NULL;
                pool->name = NULL;
        }
        return pool;
}
EXPORT_SYMBOL(gen_pool_create);

/**
 * gen_pool_add_owner- 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
 * @owner: private data the publisher would like to recall at alloc time
 *
 * 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_owner(struct gen_pool *pool, unsigned long virt, phys_addr_t phys,
                 size_t size, int nid, void *owner)
{
        struct gen_pool_chunk *chunk;
        unsigned long nbits = size >> pool->min_alloc_order;
        unsigned long nbytes = sizeof(struct gen_pool_chunk) +
                                BITS_TO_LONGS(nbits) * sizeof(long);

        chunk = vzalloc_node(nbytes, nid);
        if (unlikely(chunk == NULL))
                return -ENOMEM;

        chunk->phys_addr = phys;
        chunk->start_addr = virt;
        chunk->end_addr = virt + size - 1;
        chunk->owner = owner;
        atomic_long_set(&chunk->avail, size);

        spin_lock(&pool->lock);
        list_add_rcu(&chunk->next_chunk, &pool->chunks);
        spin_unlock(&pool->lock);

        return 0;
}
EXPORT_SYMBOL(gen_pool_add_owner);

/**
 * 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 gen_pool_chunk *chunk;
        phys_addr_t paddr = -1;

        rcu_read_lock();
        list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk) {
                if (addr >= chunk->start_addr && addr <= chunk->end_addr) {
                        paddr = chunk->phys_addr + (addr - chunk->start_addr);
                        break;
                }
        }
        rcu_read_unlock();

        return paddr;
}
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;
        unsigned long 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_size(chunk) >> order;
                bit = find_next_bit(chunk->bits, end_bit, 0);
                BUG_ON(bit < end_bit);

                vfree(chunk);
        }
        kfree_const(pool->name);
        kfree(pool);
}
EXPORT_SYMBOL(gen_pool_destroy);

/**
 * gen_pool_alloc_algo_owner - allocate special memory from the pool
 * @pool: pool to allocate from
 * @size: number of bytes to allocate from the pool
 * @algo: algorithm passed from caller
 * @data: data passed to algorithm
 * @owner: optionally retrieve the chunk owner
 *
 * Allocate the requested number of bytes from the specified pool.
 * Uses the pool allocation function (with first-fit algorithm by default).
 * Can not be used in NMI handler on architectures without
 * NMI-safe cmpxchg implementation.
 */
unsigned long gen_pool_alloc_algo_owner(struct gen_pool *pool, size_t size,
                genpool_algo_t algo, void *data, void **owner)
{
        struct gen_pool_chunk *chunk;
        unsigned long addr = 0;
        int order = pool->min_alloc_order;
        unsigned long nbits, start_bit, end_bit, remain;

#ifndef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG
        BUG_ON(in_nmi());
#endif

        if (owner)
                *owner = NULL;

        if (size == 0)
                return 0;

        nbits = (size + (1UL << order) - 1) >> order;
        rcu_read_lock();
        list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk) {
                if (size > atomic_long_read(&chunk->avail))
                        continue;

                start_bit = 0;
                end_bit = chunk_size(chunk) >> order;
retry:
                start_bit = algo(chunk->bits, end_bit, start_bit,
                                 nbits, data, pool, chunk->start_addr);
                if (start_bit >= end_bit)
                        continue;
                remain = bitmap_set_ll(chunk->bits, start_bit, nbits);
                if (remain) {
                        remain = bitmap_clear_ll(chunk->bits, start_bit,
                                                 nbits - remain);
                        BUG_ON(remain);
                        goto retry;
                }

                addr = chunk->start_addr + ((unsigned long)start_bit << order);
                size = nbits << order;
                atomic_long_sub(size, &chunk->avail);
                if (owner)
                        *owner = chunk->owner;
                break;
        }
        rcu_read_unlock();
        return addr;
}
EXPORT_SYMBOL(gen_pool_alloc_algo_owner);

/**
 * gen_pool_dma_alloc - allocate special memory from the pool for DMA usage
 * @pool: pool to allocate from
 * @size: number of bytes to allocate from the pool
 * @dma: dma-view physical address return value.  Use %NULL if unneeded.
 *
 * Allocate the requested number of bytes from the specified pool.
 * Uses the pool allocation function (with first-fit algorithm by default).
 * Can not be used in NMI handler on architectures without
 * NMI-safe cmpxchg implementation.
 *
 * Return: virtual address of the allocated memory, or %NULL on failure
 */
void *gen_pool_dma_alloc(struct gen_pool *pool, size_t size, dma_addr_t *dma)
{
        return gen_pool_dma_alloc_algo(pool, size, dma, pool->algo, pool->data);
}
EXPORT_SYMBOL(gen_pool_dma_alloc);

/**
 * gen_pool_dma_alloc_algo - allocate special memory from the pool for DMA
 * usage with the given pool algorithm
 * @pool: pool to allocate from
 * @size: number of bytes to allocate from the pool
 * @dma: DMA-view physical address return value. Use %NULL if unneeded.
 * @algo: algorithm passed from caller
 * @data: data passed to algorithm
 *
 * Allocate the requested number of bytes from the specified pool. Uses the
 * given pool allocation function. Can not be used in NMI handler on
 * architectures without NMI-safe cmpxchg implementation.
 *
 * Return: virtual address of the allocated memory, or %NULL on failure
 */
void *gen_pool_dma_alloc_algo(struct gen_pool *pool, size_t size,
                dma_addr_t *dma, genpool_algo_t algo, void *data)
{
        unsigned long vaddr;

        if (!pool)
                return NULL;

        vaddr = gen_pool_alloc_algo(pool, size, algo, data);
        if (!vaddr)
                return NULL;

        if (dma)
                *dma = gen_pool_virt_to_phys(pool, vaddr);

        return (void *)vaddr;
}
EXPORT_SYMBOL(gen_pool_dma_alloc_algo);

/**
 * gen_pool_dma_alloc_align - allocate special memory from the pool for DMA
 * usage with the given alignment
 * @pool: pool to allocate from
 * @size: number of bytes to allocate from the pool
 * @dma: DMA-view physical address return value. Use %NULL if unneeded.
 * @align: alignment in bytes for starting address
 *
 * Allocate the requested number bytes from the specified pool, with the given
 * alignment restriction. Can not be used in NMI handler on architectures
 * without NMI-safe cmpxchg implementation.
 *
 * Return: virtual address of the allocated memory, or %NULL on failure
 */
void *gen_pool_dma_alloc_align(struct gen_pool *pool, size_t size,
                dma_addr_t *dma, int align)
{
        struct genpool_data_align data = { .align = align };

        return gen_pool_dma_alloc_algo(pool, size, dma,
                        gen_pool_first_fit_align, &data);
}
EXPORT_SYMBOL(gen_pool_dma_alloc_align);

/**
 * gen_pool_dma_zalloc - allocate special zeroed memory from the pool for
 * DMA usage
 * @pool: pool to allocate from
 * @size: number of bytes to allocate from the pool
 * @dma: dma-view physical address return value.  Use %NULL if unneeded.
 *
 * Allocate the requested number of zeroed bytes from the specified pool.
 * Uses the pool allocation function (with first-fit algorithm by default).
 * Can not be used in NMI handler on architectures without
 * NMI-safe cmpxchg implementation.
 *
 * Return: virtual address of the allocated zeroed memory, or %NULL on failure
 */
void *gen_pool_dma_zalloc(struct gen_pool *pool, size_t size, dma_addr_t *dma)
{
        return gen_pool_dma_zalloc_algo(pool, size, dma, pool->algo, pool->data);
}
EXPORT_SYMBOL(gen_pool_dma_zalloc);

/**
 * gen_pool_dma_zalloc_algo - allocate special zeroed memory from the pool for
 * DMA usage with the given pool algorithm
 * @pool: pool to allocate from
 * @size: number of bytes to allocate from the pool
 * @dma: DMA-view physical address return value. Use %NULL if unneeded.
 * @algo: algorithm passed from caller
 * @data: data passed to algorithm
 *
 * Allocate the requested number of zeroed bytes from the specified pool. Uses
 * the given pool allocation function. Can not be used in NMI handler on
 * architectures without NMI-safe cmpxchg implementation.
 *
 * Return: virtual address of the allocated zeroed memory, or %NULL on failure
 */
void *gen_pool_dma_zalloc_algo(struct gen_pool *pool, size_t size,
                dma_addr_t *dma, genpool_algo_t algo, void *data)
{
        void *vaddr = gen_pool_dma_alloc_algo(pool, size, dma, algo, data);

        if (vaddr)
                memset(vaddr, 0, size);

        return vaddr;
}
EXPORT_SYMBOL(gen_pool_dma_zalloc_algo);

/**
 * gen_pool_dma_zalloc_align - allocate special zeroed memory from the pool for
 * DMA usage with the given alignment
 * @pool: pool to allocate from
 * @size: number of bytes to allocate from the pool
 * @dma: DMA-view physical address return value. Use %NULL if unneeded.
 * @align: alignment in bytes for starting address
 *
 * Allocate the requested number of zeroed bytes from the specified pool,
 * with the given alignment restriction. Can not be used in NMI handler on
 * architectures without NMI-safe cmpxchg implementation.
 *
 * Return: virtual address of the allocated zeroed memory, or %NULL on failure
 */
void *gen_pool_dma_zalloc_align(struct gen_pool *pool, size_t size,
                dma_addr_t *dma, int align)
{
        struct genpool_data_align data = { .align = align };

        return gen_pool_dma_zalloc_algo(pool, size, dma,
                        gen_pool_first_fit_align, &data);
}
EXPORT_SYMBOL(gen_pool_dma_zalloc_align);

/**
 * gen_pool_free_owner - 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
 * @owner: private data stashed at gen_pool_add() time
 *
 * Free previously allocated special memory back to the specified
 * pool.  Can not be used in NMI handler on architectures without
 * NMI-safe cmpxchg implementation.
 */
void gen_pool_free_owner(struct gen_pool *pool, unsigned long addr, size_t size,
                void **owner)
{
        struct gen_pool_chunk *chunk;
        int order = pool->min_alloc_order;
        unsigned long start_bit, nbits, remain;

#ifndef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG
        BUG_ON(in_nmi());
#endif

        if (owner)
                *owner = NULL;

        nbits = (size + (1UL << order) - 1) >> order;
        rcu_read_lock();
        list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk) {
                if (addr >= chunk->start_addr && addr <= chunk->end_addr) {
                        BUG_ON(addr + size - 1 > chunk->end_addr);
                        start_bit = (addr - chunk->start_addr) >> order;
                        remain = bitmap_clear_ll(chunk->bits, start_bit, nbits);
                        BUG_ON(remain);
                        size = nbits << order;
                        atomic_long_add(size, &chunk->avail);
                        if (owner)
                                *owner = chunk->owner;
                        rcu_read_unlock();
                        return;
                }
        }
        rcu_read_unlock();
        BUG();
}
EXPORT_SYMBOL(gen_pool_free_owner);

/**
 * gen_pool_for_each_chunk - call func for every chunk of generic memory pool
 * @pool:       the generic memory pool
 * @func:       func to call
 * @data:       additional data used by @func
 *
 * Call @func for every chunk of generic memory pool.  The @func is
 * called with rcu_read_lock held.
 */
void gen_pool_for_each_chunk(struct gen_pool *pool,
        void (*func)(struct gen_pool *pool, struct gen_pool_chunk *chunk, void *data),
        void *data)
{
        struct gen_pool_chunk *chunk;

        rcu_read_lock();
        list_for_each_entry_rcu(chunk, &(pool)->chunks, next_chunk)
                func(pool, chunk, data);
        rcu_read_unlock();
}
EXPORT_SYMBOL(gen_pool_for_each_chunk);

/**
 * gen_pool_has_addr - checks if an address falls within the range of a pool
 * @pool:       the generic memory pool
 * @start:      start address
 * @size:       size of the region
 *
 * Check if the range of addresses falls within the specified pool. Returns
 * true if the entire range is contained in the pool and false otherwise.
 */
bool gen_pool_has_addr(struct gen_pool *pool, unsigned long start,
                        size_t size)
{
        bool found = false;
        unsigned long end = start + size - 1;
        struct gen_pool_chunk *chunk;

        rcu_read_lock();
        list_for_each_entry_rcu(chunk, &(pool)->chunks, next_chunk) {
                if (start >= chunk->start_addr && start <= chunk->end_addr) {
                        if (end <= chunk->end_addr) {
                                found = true;
                                break;
                        }
                }
        }
        rcu_read_unlock();
        return found;
}
EXPORT_SYMBOL(gen_pool_has_addr);

/**
 * gen_pool_avail - get available free space of the pool
 * @pool: pool to get available free space
 *
 * Return available free space of the specified pool.
 */
size_t gen_pool_avail(struct gen_pool *pool)
{
        struct gen_pool_chunk *chunk;
        size_t avail = 0;

        rcu_read_lock();
        list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk)
                avail += atomic_long_read(&chunk->avail);
        rcu_read_unlock();
        return avail;
}
EXPORT_SYMBOL_GPL(gen_pool_avail);

/**
 * gen_pool_size - get size in bytes of memory managed by the pool
 * @pool: pool to get size
 *
 * Return size in bytes of memory managed by the pool.
 */
size_t gen_pool_size(struct gen_pool *pool)
{
        struct gen_pool_chunk *chunk;
        size_t size = 0;

        rcu_read_lock();
        list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk)
                size += chunk_size(chunk);
        rcu_read_unlock();
        return size;
}
EXPORT_SYMBOL_GPL(gen_pool_size);

/**
 * gen_pool_set_algo - set the allocation algorithm
 * @pool: pool to change allocation algorithm
 * @algo: custom algorithm function
 * @data: additional data used by @algo
 *
 * Call @algo for each memory allocation in the pool.
 * If @algo is NULL use gen_pool_first_fit as default
 * memory allocation function.
 */
void gen_pool_set_algo(struct gen_pool *pool, genpool_algo_t algo, void *data)
{
        rcu_read_lock();

        pool->algo = algo;
        if (!pool->algo)
                pool->algo = gen_pool_first_fit;

        pool->data = data;

        rcu_read_unlock();
}
EXPORT_SYMBOL(gen_pool_set_algo);

/**
 * gen_pool_first_fit - find the first available region
 * of memory matching the size requirement (no alignment constraint)
 * @map: The address to base the search on
 * @size: The bitmap size in bits
 * @start: The bitnumber to start searching at
 * @nr: The number of zeroed bits we're looking for
 * @data: additional data - unused
 * @pool: pool to find the fit region memory from
 */
unsigned long gen_pool_first_fit(unsigned long *map, unsigned long size,
                unsigned long start, unsigned int nr, void *data,
                struct gen_pool *pool, unsigned long start_addr)
{
        return bitmap_find_next_zero_area(map, size, start, nr, 0);
}
EXPORT_SYMBOL(gen_pool_first_fit);

/**
 * gen_pool_first_fit_align - find the first available region
 * of memory matching the size requirement (alignment constraint)
 * @map: The address to base the search on
 * @size: The bitmap size in bits
 * @start: The bitnumber to start searching at
 * @nr: The number of zeroed bits we're looking for
 * @data: data for alignment
 * @pool: pool to get order from
 */
unsigned long gen_pool_first_fit_align(unsigned long *map, unsigned long size,
                unsigned long start, unsigned int nr, void *data,
                struct gen_pool *pool, unsigned long start_addr)
{
        struct genpool_data_align *alignment;
        unsigned long align_mask, align_off;
        int order;

        alignment = data;
        order = pool->min_alloc_order;
        align_mask = ((alignment->align + (1UL << order) - 1) >> order) - 1;
        align_off = (start_addr & (alignment->align - 1)) >> order;

        return bitmap_find_next_zero_area_off(map, size, start, nr,
                                              align_mask, align_off);
}
EXPORT_SYMBOL(gen_pool_first_fit_align);

/**
 * gen_pool_fixed_alloc - reserve a specific region
 * @map: The address to base the search on
 * @size: The bitmap size in bits
 * @start: The bitnumber to start searching at
 * @nr: The number of zeroed bits we're looking for
 * @data: data for alignment
 * @pool: pool to get order from
 */
unsigned long gen_pool_fixed_alloc(unsigned long *map, unsigned long size,
                unsigned long start, unsigned int nr, void *data,
                struct gen_pool *pool, unsigned long start_addr)
{
        struct genpool_data_fixed *fixed_data;
        int order;
        unsigned long offset_bit;
        unsigned long start_bit;

        fixed_data = data;
        order = pool->min_alloc_order;
        offset_bit = fixed_data->offset >> order;
        if (WARN_ON(fixed_data->offset & ((1UL << order) - 1)))
                return size;

        start_bit = bitmap_find_next_zero_area(map, size,
                        start + offset_bit, nr, 0);
        if (start_bit != offset_bit)
                start_bit = size;
        return start_bit;
}
EXPORT_SYMBOL(gen_pool_fixed_alloc);

/**
 * gen_pool_first_fit_order_align - find the first available region
 * of memory matching the size requirement. The region will be aligned
 * to the order of the size specified.
 * @map: The address to base the search on
 * @size: The bitmap size in bits
 * @start: The bitnumber to start searching at
 * @nr: The number of zeroed bits we're looking for
 * @data: additional data - unused
 * @pool: pool to find the fit region memory from
 */
unsigned long gen_pool_first_fit_order_align(unsigned long *map,
                unsigned long size, unsigned long start,
                unsigned int nr, void *data, struct gen_pool *pool,
                unsigned long start_addr)
{
        unsigned long align_mask = roundup_pow_of_two(nr) - 1;

        return bitmap_find_next_zero_area(map, size, start, nr, align_mask);
}
EXPORT_SYMBOL(gen_pool_first_fit_order_align);

/**
 * gen_pool_best_fit - find the best fitting region of memory
 * macthing the size requirement (no alignment constraint)
 * @map: The address to base the search on
 * @size: The bitmap size in bits
 * @start: The bitnumber to start searching at
 * @nr: The number of zeroed bits we're looking for
 * @data: additional data - unused
 * @pool: pool to find the fit region memory from
 *
 * Iterate over the bitmap to find the smallest free region
 * which we can allocate the memory.
 */
unsigned long gen_pool_best_fit(unsigned long *map, unsigned long size,
                unsigned long start, unsigned int nr, void *data,
                struct gen_pool *pool, unsigned long start_addr)
{
        unsigned long start_bit = size;
        unsigned long len = size + 1;
        unsigned long index;

        index = bitmap_find_next_zero_area(map, size, start, nr, 0);

        while (index < size) {
                unsigned long next_bit = find_next_bit(map, size, index + nr);
                if ((next_bit - index) < len) {
                        len = next_bit - index;
                        start_bit = index;
                        if (len == nr)
                                return start_bit;
                }
                index = bitmap_find_next_zero_area(map, size,
                                                   next_bit + 1, nr, 0);
        }

        return start_bit;
}
EXPORT_SYMBOL(gen_pool_best_fit);

static void devm_gen_pool_release(struct device *dev, void *res)
{
        gen_pool_destroy(*(struct gen_pool **)res);
}

static int devm_gen_pool_match(struct device *dev, void *res, void *data)
{
        struct gen_pool **p = res;

        /* NULL data matches only a pool without an assigned name */
        if (!data && !(*p)->name)
                return 1;

        if (!data || !(*p)->name)
                return 0;

        return !strcmp((*p)->name, data);
}

/**
 * gen_pool_get - Obtain the gen_pool (if any) for a device
 * @dev: device to retrieve the gen_pool from
 * @name: name of a gen_pool or NULL, identifies a particular gen_pool on device
 *
 * Returns the gen_pool for the device if one is present, or NULL.
 */
struct gen_pool *gen_pool_get(struct device *dev, const char *name)
{
        struct gen_pool **p;

        p = devres_find(dev, devm_gen_pool_release, devm_gen_pool_match,
                        (void *)name);
        if (!p)
                return NULL;
        return *p;
}
EXPORT_SYMBOL_GPL(gen_pool_get);

/**
 * devm_gen_pool_create - managed gen_pool_create
 * @dev: device that provides the gen_pool
 * @min_alloc_order: log base 2 of number of bytes each bitmap bit represents
 * @nid: node selector for allocated gen_pool, %NUMA_NO_NODE for all nodes
 * @name: name of a gen_pool or NULL, identifies a particular gen_pool on device
 *
 * Create a new special memory pool that can be used to manage special purpose
 * memory not managed by the regular kmalloc/kfree interface. The pool will be
 * automatically destroyed by the device management code.
 */
struct gen_pool *devm_gen_pool_create(struct device *dev, int min_alloc_order,
                                      int nid, const char *name)
{
        struct gen_pool **ptr, *pool;
        const char *pool_name = NULL;

        /* Check that genpool to be created is uniquely addressed on device */
        if (gen_pool_get(dev, name))
                return ERR_PTR(-EINVAL);

        if (name) {
                pool_name = kstrdup_const(name, GFP_KERNEL);
                if (!pool_name)
                        return ERR_PTR(-ENOMEM);
        }

        ptr = devres_alloc(devm_gen_pool_release, sizeof(*ptr), GFP_KERNEL);
        if (!ptr)
                goto free_pool_name;

        pool = gen_pool_create(min_alloc_order, nid);
        if (!pool)
                goto free_devres;

        *ptr = pool;
        pool->name = pool_name;
        devres_add(dev, ptr);

        return pool;

free_devres:
        devres_free(ptr);
free_pool_name:
        kfree_const(pool_name);

        return ERR_PTR(-ENOMEM);
}
EXPORT_SYMBOL(devm_gen_pool_create);

#ifdef CONFIG_OF
/**
 * of_gen_pool_get - find a pool by phandle property
 * @np: device node
 * @propname: property name containing phandle(s)
 * @index: index into the phandle array
 *
 * Returns the pool that contains the chunk starting at the physical
 * address of the device tree node pointed at by the phandle property,
 * or NULL if not found.
 */
struct gen_pool *of_gen_pool_get(struct device_node *np,
        const char *propname, int index)
{
        struct platform_device *pdev;
        struct device_node *np_pool, *parent;
        const char *name = NULL;
        struct gen_pool *pool = NULL;

        np_pool = of_parse_phandle(np, propname, index);
        if (!np_pool)
                return NULL;

        pdev = of_find_device_by_node(np_pool);
        if (!pdev) {
                /* Check if named gen_pool is created by parent node device */
                parent = of_get_parent(np_pool);
                pdev = of_find_device_by_node(parent);
                of_node_put(parent);

                of_property_read_string(np_pool, "label", &name);
                if (!name)
                        name = np_pool->name;
        }
        if (pdev)
                pool = gen_pool_get(&pdev->dev, name);
        of_node_put(np_pool);

        return pool;
}
EXPORT_SYMBOL_GPL(of_gen_pool_get);
#endif /* CONFIG_OF */