/*

   * 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.

   *

   * This source code is licensed under the GNU General Public License,
   * Version 2.  See the file COPYING for more details.
   */

  #ifndef __GENALLOC_H__
  #define __GENALLOC_H__

  /*

   *  General purpose special memory pool descriptor.

   */

  struct gen_pool {

  	spinlock_t lock;

  	struct list_head chunks;	/* list of chunks in this pool */
  	int min_alloc_order;		/* minimum allocation order */

  };
  
  /*

   *  General purpose special memory pool chunk descriptor.

   */

  struct gen_pool_chunk {

  	struct list_head next_chunk;	/* next chunk in pool */

  	atomic_t avail;

  	phys_addr_t phys_addr;		/* physical starting address of memory chunk */

  	unsigned long start_addr;	/* starting address of memory chunk */
  	unsigned long end_addr;		/* ending address of memory chunk */
  	unsigned long bits[0];		/* bitmap for allocating memory chunk */

  };

  extern struct gen_pool *gen_pool_create(int, int);

  extern phys_addr_t gen_pool_virt_to_phys(struct gen_pool *pool, unsigned long);
  extern int gen_pool_add_virt(struct gen_pool *, unsigned long, phys_addr_t,
  			     size_t, int);
  /**
   * 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.
   *
   * Returns 0 on success or a -ve errno on failure.
   */
  static inline int gen_pool_add(struct gen_pool *pool, unsigned long addr,
  			       size_t size, int nid)
  {
  	return gen_pool_add_virt(pool, addr, -1, size, nid);
  }

  extern void gen_pool_destroy(struct gen_pool *);

  extern unsigned long gen_pool_alloc(struct gen_pool *, size_t);
  extern void gen_pool_free(struct gen_pool *, unsigned long, size_t);

  extern void gen_pool_for_each_chunk(struct gen_pool *,
  	void (*)(struct gen_pool *, struct gen_pool_chunk *, void *), void *);
  extern size_t gen_pool_avail(struct gen_pool *);
  extern size_t gen_pool_size(struct gen_pool *);

  #endif /* __GENALLOC_H__ */