LXR linux/include/linux/genalloc.h

   1/*
   2 * Basic general purpose allocator for managing special purpose
   3 * memory, for example, memory that is not managed by the regular
   4 * kmalloc/kfree interface.  Uses for this includes on-device special
   5 * memory, uncached memory etc.
   6 *
   7 * It is safe to use the allocator in NMI handlers and other special
   8 * unblockable contexts that could otherwise deadlock on locks.  This
   9 * is implemented by using atomic operations and retries on any
  10 * conflicts.  The disadvantage is that there may be livelocks in
  11 * extreme cases.  For better scalability, one allocator can be used
  12 * for each CPU.
  13 *
  14 * The lockless operation only works if there is enough memory
  15 * available.  If new memory is added to the pool a lock has to be
  16 * still taken.  So any user relying on locklessness has to ensure
  17 * that sufficient memory is preallocated.
  18 *
  19 * The basic atomic operation of this allocator is cmpxchg on long.
  20 * On architectures that don't have NMI-safe cmpxchg implementation,
  21 * the allocator can NOT be used in NMI handler.  So code uses the
  22 * allocator in NMI handler should depend on
  23 * CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG.
  24 *
  25 * This source code is licensed under the GNU General Public License,
  26 * Version 2.  See the file COPYING for more details.
  27 */
  28
  29
  30#ifndef __GENALLOC_H__
  31#define __GENALLOC_H__
  32
  33struct device;
  34struct device_node;
  35
  36/**
  37 * Allocation callback function type definition
  38 * @map: Pointer to bitmap
  39 * @size: The bitmap size in bits
  40 * @start: The bitnumber to start searching at
  41 * @nr: The number of zeroed bits we're looking for
  42 * @data: optional additional data used by @genpool_algo_t
  43 */
  44typedef unsigned long (*genpool_algo_t)(unsigned long *map,
  45                        unsigned long size,
  46                        unsigned long start,
  47                        unsigned int nr,
  48                        void *data);
  49
  50/*
  51 *  General purpose special memory pool descriptor.
  52 */
  53struct gen_pool {
  54        spinlock_t lock;
  55        struct list_head chunks;        /* list of chunks in this pool */
  56        int min_alloc_order;            /* minimum allocation order */
  57
  58        genpool_algo_t algo;            /* allocation function */
  59        void *data;
  60};
  61
  62/*
  63 *  General purpose special memory pool chunk descriptor.
  64 */
  65struct gen_pool_chunk {
  66        struct list_head next_chunk;    /* next chunk in pool */
  67        atomic_t avail;
  68        phys_addr_t phys_addr;          /* physical starting address of memory chunk */
  69        unsigned long start_addr;       /* starting address of memory chunk */
  70        unsigned long end_addr;         /* ending address of memory chunk */
  71        unsigned long bits[0];          /* bitmap for allocating memory chunk */
  72};
  73
  74extern struct gen_pool *gen_pool_create(int, int);
  75extern phys_addr_t gen_pool_virt_to_phys(struct gen_pool *pool, unsigned long);
  76extern int gen_pool_add_virt(struct gen_pool *, unsigned long, phys_addr_t,
  77                             size_t, int);
  78/**
  79 * gen_pool_add - add a new chunk of special memory to the pool
  80 * @pool: pool to add new memory chunk to
  81 * @addr: starting address of memory chunk to add to pool
  82 * @size: size in bytes of the memory chunk to add to pool
  83 * @nid: node id of the node the chunk structure and bitmap should be
  84 *       allocated on, or -1
  85 *
  86 * Add a new chunk of special memory to the specified pool.
  87 *
  88 * Returns 0 on success or a -ve errno on failure.
  89 */
  90static inline int gen_pool_add(struct gen_pool *pool, unsigned long addr,
  91                               size_t size, int nid)
  92{
  93        return gen_pool_add_virt(pool, addr, -1, size, nid);
  94}
  95extern void gen_pool_destroy(struct gen_pool *);
  96extern unsigned long gen_pool_alloc(struct gen_pool *, size_t);
  97extern void gen_pool_free(struct gen_pool *, unsigned long, size_t);
  98extern void gen_pool_for_each_chunk(struct gen_pool *,
  99        void (*)(struct gen_pool *, struct gen_pool_chunk *, void *), void *);
 100extern size_t gen_pool_avail(struct gen_pool *);
 101extern size_t gen_pool_size(struct gen_pool *);
 102
 103extern void gen_pool_set_algo(struct gen_pool *pool, genpool_algo_t algo,
 104                void *data);
 105
 106extern unsigned long gen_pool_first_fit(unsigned long *map, unsigned long size,
 107                unsigned long start, unsigned int nr, void *data);
 108
 109extern unsigned long gen_pool_best_fit(unsigned long *map, unsigned long size,
 110                unsigned long start, unsigned int nr, void *data);
 111
 112extern struct gen_pool *devm_gen_pool_create(struct device *dev,
 113                int min_alloc_order, int nid);
 114extern struct gen_pool *dev_get_gen_pool(struct device *dev);
 115
 116#ifdef CONFIG_OF
 117extern struct gen_pool *of_get_named_gen_pool(struct device_node *np,
 118        const char *propname, int index);
 119#else
 120static inline struct gen_pool *of_get_named_gen_pool(struct device_node *np,
 121        const char *propname, int index)
 122{
 123        return NULL;
 124}
 125#endif
 126#endif /* __GENALLOC_H__ */
 127