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
  33 struct device;
  34 struct 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  */
  44 typedef 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  */
  53 struct 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  */
  65 struct 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;       /* start address of memory chunk */
  70         unsigned long end_addr;         /* end address of memory chunk (inclusive) */
  71         unsigned long bits[0];          /* bitmap for allocating memory chunk */
  72 };
  73
  74 extern struct gen_pool *gen_pool_create(int, int);
  75 extern phys_addr_t gen_pool_virt_to_phys(struct gen_pool *pool, unsigned long);
  76 extern 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  */
  90 static 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 }
  95 extern void gen_pool_destroy(struct gen_pool *);
  96 extern unsigned long gen_pool_alloc(struct gen_pool *, size_t);
  97 extern void gen_pool_free(struct gen_pool *, unsigned long, size_t);
  98 extern void gen_pool_for_each_chunk(struct gen_pool *,
  99         void (*)(struct gen_pool *, struct gen_pool_chunk *, void *), void *);
 100 extern size_t gen_pool_avail(struct gen_pool *);
 101 extern size_t gen_pool_size(struct gen_pool *);
 102
 103 extern void gen_pool_set_algo(struct gen_pool *pool, genpool_algo_t algo,
 104                 void *data);
 105
 106 extern unsigned long gen_pool_first_fit(unsigned long *map, unsigned long size,
 107                 unsigned long start, unsigned int nr, void *data);
 108
 109 extern unsigned long gen_pool_best_fit(unsigned long *map, unsigned long size,
 110                 unsigned long start, unsigned int nr, void *data);
 111
 112 extern struct gen_pool *devm_gen_pool_create(struct device *dev,
 113                 int min_alloc_order, int nid);
 114 extern struct gen_pool *dev_get_gen_pool(struct device *dev);
 115
 116 #ifdef CONFIG_OF
 117 extern struct gen_pool *of_get_named_gen_pool(struct device_node *np,
 118         const char *propname, int index);
 119 #else
 120 static 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__ */