lib/genalloc.c

   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  * Copyright 2005 (C) Jes Sorensen <jes@trained-monkey.org>
  26  *
  27  * This source code is licensed under the GNU General Public License,
  28  * Version 2.  See the file COPYING for more details.
  29  */
  30
  31 #include <linux/slab.h>
  32 #include <linux/export.h>
  33 #include <linux/bitmap.h>
  34 #include <linux/rculist.h>
  35 #include <linux/interrupt.h>
  36 #include <linux/genalloc.h>
  37 #include <linux/of_device.h>
  38
  39 static inline size_t chunk_size(const struct gen_pool_chunk *chunk)
  40 {
  41         return chunk->end_addr - chunk->start_addr + 1;
  42 }
  43
  44 static int set_bits_ll(unsigned long *addr, unsigned long mask_to_set)
  45 {
  46         unsigned long val, nval;
  47
  48         nval = *addr;
  49         do {
  50                 val = nval;
  51                 if (val & mask_to_set)
  52                         return -EBUSY;
  53                 cpu_relax();
  54         } while ((nval = cmpxchg(addr, val, val | mask_to_set)) != val);
  55
  56         return 0;
  57 }
  58
  59 static int clear_bits_ll(unsigned long *addr, unsigned long mask_to_clear)
  60 {
  61         unsigned long val, nval;
  62
  63         nval = *addr;
  64         do {
  65                 val = nval;
  66                 if ((val & mask_to_clear) != mask_to_clear)
  67                         return -EBUSY;
  68                 cpu_relax();
  69         } while ((nval = cmpxchg(addr, val, val & ~mask_to_clear)) != val);
  70
  71         return 0;
  72 }
  73
  74 /*
  75  * bitmap_set_ll - set the specified number of bits at the specified position
  76  * @map: pointer to a bitmap
  77  * @start: a bit position in @map
  78  * @nr: number of bits to set
  79  *
  80  * Set @nr bits start from @start in @map lock-lessly. Several users
  81  * can set/clear the same bitmap simultaneously without lock. If two
  82  * users set the same bit, one user will return remain bits, otherwise
  83  * return 0.
  84  */
  85 static int bitmap_set_ll(unsigned long *map, int start, int nr)
  86 {
  87         unsigned long *p = map + BIT_WORD(start);
  88         const int size = start + nr;
  89         int bits_to_set = BITS_PER_LONG - (start % BITS_PER_LONG);
  90         unsigned long mask_to_set = BITMAP_FIRST_WORD_MASK(start);
  91
  92         while (nr - bits_to_set >= 0) {
  93                 if (set_bits_ll(p, mask_to_set))
  94                         return nr;
  95                 nr -= bits_to_set;
  96                 bits_to_set = BITS_PER_LONG;
  97                 mask_to_set = ~0UL;
  98                 p++;
  99         }
 100         if (nr) {
 101                 mask_to_set &= BITMAP_LAST_WORD_MASK(size);
 102                 if (set_bits_ll(p, mask_to_set))
 103                         return nr;
 104         }
 105
 106         return 0;
 107 }
 108
 109 /*
 110  * bitmap_clear_ll - clear the specified number of bits at the specified position
 111  * @map: pointer to a bitmap
 112  * @start: a bit position in @map
 113  * @nr: number of bits to set
 114  *
 115  * Clear @nr bits start from @start in @map lock-lessly. Several users
 116  * can set/clear the same bitmap simultaneously without lock. If two
 117  * users clear the same bit, one user will return remain bits,
 118  * otherwise return 0.
 119  */
 120 static int bitmap_clear_ll(unsigned long *map, int start, int nr)
 121 {
 122         unsigned long *p = map + BIT_WORD(start);
 123         const int size = start + nr;
 124         int bits_to_clear = BITS_PER_LONG - (start % BITS_PER_LONG);
 125         unsigned long mask_to_clear = BITMAP_FIRST_WORD_MASK(start);
 126
 127         while (nr - bits_to_clear >= 0) {
 128                 if (clear_bits_ll(p, mask_to_clear))
 129                         return nr;
 130                 nr -= bits_to_clear;
 131                 bits_to_clear = BITS_PER_LONG;
 132                 mask_to_clear = ~0UL;
 133                 p++;
 134         }
 135         if (nr) {
 136                 mask_to_clear &= BITMAP_LAST_WORD_MASK(size);
 137                 if (clear_bits_ll(p, mask_to_clear))
 138                         return nr;
 139         }
 140
 141         return 0;
 142 }
 143
 144 /**
 145  * gen_pool_create - create a new special memory pool
 146  * @min_alloc_order: log base 2 of number of bytes each bitmap bit represents
 147  * @nid: node id of the node the pool structure should be allocated on, or -1
 148  *
 149  * Create a new special memory pool that can be used to manage special purpose
 150  * memory not managed by the regular kmalloc/kfree interface.
 151  */
 152 struct gen_pool *gen_pool_create(int min_alloc_order, int nid)
 153 {
 154         struct gen_pool *pool;
 155
 156         pool = kmalloc_node(sizeof(struct gen_pool), GFP_KERNEL, nid);
 157         if (pool != NULL) {
 158                 spin_lock_init(&pool->lock);
 159                 INIT_LIST_HEAD(&pool->chunks);
 160                 pool->min_alloc_order = min_alloc_order;
 161                 pool->algo = gen_pool_first_fit;
 162                 pool->data = NULL;
 163                 pool->name = NULL;
 164         }
 165         return pool;
 166 }
 167 EXPORT_SYMBOL(gen_pool_create);
 168
 169 /**
 170  * gen_pool_add_virt - add a new chunk of special memory to the pool
 171  * @pool: pool to add new memory chunk to
 172  * @virt: virtual starting address of memory chunk to add to pool
 173  * @phys: physical starting address of memory chunk to add to pool
 174  * @size: size in bytes of the memory chunk to add to pool
 175  * @nid: node id of the node the chunk structure and bitmap should be
 176  *       allocated on, or -1
 177  *
 178  * Add a new chunk of special memory to the specified pool.
 179  *
 180  * Returns 0 on success or a -ve errno on failure.
 181  */
 182 int gen_pool_add_virt(struct gen_pool *pool, unsigned long virt, phys_addr_t phys,
 183                  size_t size, int nid)
 184 {
 185         struct gen_pool_chunk *chunk;
 186         int nbits = size >> pool->min_alloc_order;
 187         int nbytes = sizeof(struct gen_pool_chunk) +
 188                                 BITS_TO_LONGS(nbits) * sizeof(long);
 189
 190         chunk = kzalloc_node(nbytes, GFP_KERNEL, nid);
 191         if (unlikely(chunk == NULL))
 192                 return -ENOMEM;
 193
 194         chunk->phys_addr = phys;
 195         chunk->start_addr = virt;
 196         chunk->end_addr = virt + size - 1;
 197         atomic_set(&chunk->avail, size);
 198
 199         spin_lock(&pool->lock);
 200         list_add_rcu(&chunk->next_chunk, &pool->chunks);
 201         spin_unlock(&pool->lock);
 202
 203         return 0;
 204 }
 205 EXPORT_SYMBOL(gen_pool_add_virt);
 206
 207 /**
 208  * gen_pool_virt_to_phys - return the physical address of memory
 209  * @pool: pool to allocate from
 210  * @addr: starting address of memory
 211  *
 212  * Returns the physical address on success, or -1 on error.
 213  */
 214 phys_addr_t gen_pool_virt_to_phys(struct gen_pool *pool, unsigned long addr)
 215 {
 216         struct gen_pool_chunk *chunk;
 217         phys_addr_t paddr = -1;
 218
 219         rcu_read_lock();
 220         list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk) {
 221                 if (addr >= chunk->start_addr && addr <= chunk->end_addr) {
 222                         paddr = chunk->phys_addr + (addr - chunk->start_addr);
 223                         break;
 224                 }
 225         }
 226         rcu_read_unlock();
 227
 228         return paddr;
 229 }
 230 EXPORT_SYMBOL(gen_pool_virt_to_phys);
 231
 232 /**
 233  * gen_pool_destroy - destroy a special memory pool
 234  * @pool: pool to destroy
 235  *
 236  * Destroy the specified special memory pool. Verifies that there are no
 237  * outstanding allocations.
 238  */
 239 void gen_pool_destroy(struct gen_pool *pool)
 240 {
 241         struct list_head *_chunk, *_next_chunk;
 242         struct gen_pool_chunk *chunk;
 243         int order = pool->min_alloc_order;
 244         int bit, end_bit;
 245
 246         list_for_each_safe(_chunk, _next_chunk, &pool->chunks) {
 247                 chunk = list_entry(_chunk, struct gen_pool_chunk, next_chunk);
 248                 list_del(&chunk->next_chunk);
 249
 250                 end_bit = chunk_size(chunk) >> order;
 251                 bit = find_next_bit(chunk->bits, end_bit, 0);
 252                 BUG_ON(bit < end_bit);
 253
 254                 kfree(chunk);
 255         }
 256         kfree_const(pool->name);
 257         kfree(pool);
 258 }
 259 EXPORT_SYMBOL(gen_pool_destroy);
 260
 261 /**
 262  * gen_pool_alloc - allocate special memory from the pool
 263  * @pool: pool to allocate from
 264  * @size: number of bytes to allocate from the pool
 265  *
 266  * Allocate the requested number of bytes from the specified pool.
 267  * Uses the pool allocation function (with first-fit algorithm by default).
 268  * Can not be used in NMI handler on architectures without
 269  * NMI-safe cmpxchg implementation.
 270  */
 271 unsigned long gen_pool_alloc(struct gen_pool *pool, size_t size)
 272 {
 273         struct gen_pool_chunk *chunk;
 274         unsigned long addr = 0;
 275         int order = pool->min_alloc_order;
 276         int nbits, start_bit = 0, end_bit, remain;
 277
 278 #ifndef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG
 279         BUG_ON(in_nmi());
 280 #endif
 281
 282         if (size == 0)
 283                 return 0;
 284
 285         nbits = (size + (1UL << order) - 1) >> order;
 286         rcu_read_lock();
 287         list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk) {
 288                 if (size > atomic_read(&chunk->avail))
 289                         continue;
 290
 291                 end_bit = chunk_size(chunk) >> order;
 292 retry:
 293                 start_bit = pool->algo(chunk->bits, end_bit, start_bit, nbits,
 294                                 pool->data);
 295                 if (start_bit >= end_bit)
 296                         continue;
 297                 remain = bitmap_set_ll(chunk->bits, start_bit, nbits);
 298                 if (remain) {
 299                         remain = bitmap_clear_ll(chunk->bits, start_bit,
 300                                                  nbits - remain);
 301                         BUG_ON(remain);
 302                         goto retry;
 303                 }
 304
 305                 addr = chunk->start_addr + ((unsigned long)start_bit << order);
 306                 size = nbits << order;
 307                 atomic_sub(size, &chunk->avail);
 308                 break;
 309         }
 310         rcu_read_unlock();
 311         return addr;
 312 }
 313 EXPORT_SYMBOL(gen_pool_alloc);
 314
 315 /**
 316  * gen_pool_dma_alloc - allocate special memory from the pool for DMA usage
 317  * @pool: pool to allocate from
 318  * @size: number of bytes to allocate from the pool
 319  * @dma: dma-view physical address return value.  Use NULL if unneeded.
 320  *
 321  * Allocate the requested number of bytes from the specified pool.
 322  * Uses the pool allocation function (with first-fit algorithm by default).
 323  * Can not be used in NMI handler on architectures without
 324  * NMI-safe cmpxchg implementation.
 325  */
 326 void *gen_pool_dma_alloc(struct gen_pool *pool, size_t size, dma_addr_t *dma)
 327 {
 328         unsigned long vaddr;
 329
 330         if (!pool)
 331                 return NULL;
 332
 333         vaddr = gen_pool_alloc(pool, size);
 334         if (!vaddr)
 335                 return NULL;
 336
 337         if (dma)
 338                 *dma = gen_pool_virt_to_phys(pool, vaddr);
 339
 340         return (void *)vaddr;
 341 }
 342 EXPORT_SYMBOL(gen_pool_dma_alloc);
 343
 344 /**
 345  * gen_pool_free - free allocated special memory back to the pool
 346  * @pool: pool to free to
 347  * @addr: starting address of memory to free back to pool
 348  * @size: size in bytes of memory to free
 349  *
 350  * Free previously allocated special memory back to the specified
 351  * pool.  Can not be used in NMI handler on architectures without
 352  * NMI-safe cmpxchg implementation.
 353  */
 354 void gen_pool_free(struct gen_pool *pool, unsigned long addr, size_t size)
 355 {
 356         struct gen_pool_chunk *chunk;
 357         int order = pool->min_alloc_order;
 358         int start_bit, nbits, remain;
 359
 360 #ifndef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG
 361         BUG_ON(in_nmi());
 362 #endif
 363
 364         nbits = (size + (1UL << order) - 1) >> order;
 365         rcu_read_lock();
 366         list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk) {
 367                 if (addr >= chunk->start_addr && addr <= chunk->end_addr) {
 368                         BUG_ON(addr + size - 1 > chunk->end_addr);
 369                         start_bit = (addr - chunk->start_addr) >> order;
 370                         remain = bitmap_clear_ll(chunk->bits, start_bit, nbits);
 371                         BUG_ON(remain);
 372                         size = nbits << order;
 373                         atomic_add(size, &chunk->avail);
 374                         rcu_read_unlock();
 375                         return;
 376                 }
 377         }
 378         rcu_read_unlock();
 379         BUG();
 380 }
 381 EXPORT_SYMBOL(gen_pool_free);
 382
 383 /**
 384  * gen_pool_for_each_chunk - call func for every chunk of generic memory pool
 385  * @pool:       the generic memory pool
 386  * @func:       func to call
 387  * @data:       additional data used by @func
 388  *
 389  * Call @func for every chunk of generic memory pool.  The @func is
 390  * called with rcu_read_lock held.
 391  */
 392 void gen_pool_for_each_chunk(struct gen_pool *pool,
 393         void (*func)(struct gen_pool *pool, struct gen_pool_chunk *chunk, void *data),
 394         void *data)
 395 {
 396         struct gen_pool_chunk *chunk;
 397
 398         rcu_read_lock();
 399         list_for_each_entry_rcu(chunk, &(pool)->chunks, next_chunk)
 400                 func(pool, chunk, data);
 401         rcu_read_unlock();
 402 }
 403 EXPORT_SYMBOL(gen_pool_for_each_chunk);
 404
 405 /**
 406  * addr_in_gen_pool - checks if an address falls within the range of a pool
 407  * @pool:       the generic memory pool
 408  * @start:      start address
 409  * @size:       size of the region
 410  *
 411  * Check if the range of addresses falls within the specified pool. Returns
 412  * true if the entire range is contained in the pool and false otherwise.
 413  */
 414 bool addr_in_gen_pool(struct gen_pool *pool, unsigned long start,
 415                         size_t size)
 416 {
 417         bool found = false;
 418         unsigned long end = start + size - 1;
 419         struct gen_pool_chunk *chunk;
 420
 421         rcu_read_lock();
 422         list_for_each_entry_rcu(chunk, &(pool)->chunks, next_chunk) {
 423                 if (start >= chunk->start_addr && start <= chunk->end_addr) {
 424                         if (end <= chunk->end_addr) {
 425                                 found = true;
 426                                 break;
 427                         }
 428                 }
 429         }
 430         rcu_read_unlock();
 431         return found;
 432 }
 433
 434 /**
 435  * gen_pool_avail - get available free space of the pool
 436  * @pool: pool to get available free space
 437  *
 438  * Return available free space of the specified pool.
 439  */
 440 size_t gen_pool_avail(struct gen_pool *pool)
 441 {
 442         struct gen_pool_chunk *chunk;
 443         size_t avail = 0;
 444
 445         rcu_read_lock();
 446         list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk)
 447                 avail += atomic_read(&chunk->avail);
 448         rcu_read_unlock();
 449         return avail;
 450 }
 451 EXPORT_SYMBOL_GPL(gen_pool_avail);
 452
 453 /**
 454  * gen_pool_size - get size in bytes of memory managed by the pool
 455  * @pool: pool to get size
 456  *
 457  * Return size in bytes of memory managed by the pool.
 458  */
 459 size_t gen_pool_size(struct gen_pool *pool)
 460 {
 461         struct gen_pool_chunk *chunk;
 462         size_t size = 0;
 463
 464         rcu_read_lock();
 465         list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk)
 466                 size += chunk_size(chunk);
 467         rcu_read_unlock();
 468         return size;
 469 }
 470 EXPORT_SYMBOL_GPL(gen_pool_size);
 471
 472 /**
 473  * gen_pool_set_algo - set the allocation algorithm
 474  * @pool: pool to change allocation algorithm
 475  * @algo: custom algorithm function
 476  * @data: additional data used by @algo
 477  *
 478  * Call @algo for each memory allocation in the pool.
 479  * If @algo is NULL use gen_pool_first_fit as default
 480  * memory allocation function.
 481  */
 482 void gen_pool_set_algo(struct gen_pool *pool, genpool_algo_t algo, void *data)
 483 {
 484         rcu_read_lock();
 485
 486         pool->algo = algo;
 487         if (!pool->algo)
 488                 pool->algo = gen_pool_first_fit;
 489
 490         pool->data = data;
 491
 492         rcu_read_unlock();
 493 }
 494 EXPORT_SYMBOL(gen_pool_set_algo);
 495
 496 /**
 497  * gen_pool_first_fit - find the first available region
 498  * of memory matching the size requirement (no alignment constraint)
 499  * @map: The address to base the search on
 500  * @size: The bitmap size in bits
 501  * @start: The bitnumber to start searching at
 502  * @nr: The number of zeroed bits we're looking for
 503  * @data: additional data - unused
 504  */
 505 unsigned long gen_pool_first_fit(unsigned long *map, unsigned long size,
 506                 unsigned long start, unsigned int nr, void *data)
 507 {
 508         return bitmap_find_next_zero_area(map, size, start, nr, 0);
 509 }
 510 EXPORT_SYMBOL(gen_pool_first_fit);
 511
 512 /**
 513  * gen_pool_first_fit_order_align - find the first available region
 514  * of memory matching the size requirement. The region will be aligned
 515  * to the order of the size specified.
 516  * @map: The address to base the search on
 517  * @size: The bitmap size in bits
 518  * @start: The bitnumber to start searching at
 519  * @nr: The number of zeroed bits we're looking for
 520  * @data: additional data - unused
 521  */
 522 unsigned long gen_pool_first_fit_order_align(unsigned long *map,
 523                 unsigned long size, unsigned long start,
 524                 unsigned int nr, void *data)
 525 {
 526         unsigned long align_mask = roundup_pow_of_two(nr) - 1;
 527
 528         return bitmap_find_next_zero_area(map, size, start, nr, align_mask);
 529 }
 530 EXPORT_SYMBOL(gen_pool_first_fit_order_align);
 531
 532 /**
 533  * gen_pool_best_fit - find the best fitting region of memory
 534  * macthing the size requirement (no alignment constraint)
 535  * @map: The address to base the search on
 536  * @size: The bitmap size in bits
 537  * @start: The bitnumber to start searching at
 538  * @nr: The number of zeroed bits we're looking for
 539  * @data: additional data - unused
 540  *
 541  * Iterate over the bitmap to find the smallest free region
 542  * which we can allocate the memory.
 543  */
 544 unsigned long gen_pool_best_fit(unsigned long *map, unsigned long size,
 545                 unsigned long start, unsigned int nr, void *data)
 546 {
 547         unsigned long start_bit = size;
 548         unsigned long len = size + 1;
 549         unsigned long index;
 550
 551         index = bitmap_find_next_zero_area(map, size, start, nr, 0);
 552
 553         while (index < size) {
 554                 int next_bit = find_next_bit(map, size, index + nr);
 555                 if ((next_bit - index) < len) {
 556                         len = next_bit - index;
 557                         start_bit = index;
 558                         if (len == nr)
 559                                 return start_bit;
 560                 }
 561                 index = bitmap_find_next_zero_area(map, size,
 562                                                    next_bit + 1, nr, 0);
 563         }
 564
 565         return start_bit;
 566 }
 567 EXPORT_SYMBOL(gen_pool_best_fit);
 568
 569 static void devm_gen_pool_release(struct device *dev, void *res)
 570 {
 571         gen_pool_destroy(*(struct gen_pool **)res);
 572 }
 573
 574 static int devm_gen_pool_match(struct device *dev, void *res, void *data)
 575 {
 576         struct gen_pool **p = res;
 577
 578         /* NULL data matches only a pool without an assigned name */
 579         if (!data && !(*p)->name)
 580                 return 1;
 581
 582         if (!data || !(*p)->name)
 583                 return 0;
 584
 585         return !strcmp((*p)->name, data);
 586 }
 587
 588 /**
 589  * gen_pool_get - Obtain the gen_pool (if any) for a device
 590  * @dev: device to retrieve the gen_pool from
 591  * @name: name of a gen_pool or NULL, identifies a particular gen_pool on device
 592  *
 593  * Returns the gen_pool for the device if one is present, or NULL.
 594  */
 595 struct gen_pool *gen_pool_get(struct device *dev, const char *name)
 596 {
 597         struct gen_pool **p;
 598
 599         p = devres_find(dev, devm_gen_pool_release, devm_gen_pool_match,
 600                         (void *)name);
 601         if (!p)
 602                 return NULL;
 603         return *p;
 604 }
 605 EXPORT_SYMBOL_GPL(gen_pool_get);
 606
 607 /**
 608  * devm_gen_pool_create - managed gen_pool_create
 609  * @dev: device that provides the gen_pool
 610  * @min_alloc_order: log base 2 of number of bytes each bitmap bit represents
 611  * @nid: node selector for allocated gen_pool, %NUMA_NO_NODE for all nodes
 612  * @name: name of a gen_pool or NULL, identifies a particular gen_pool on device
 613  *
 614  * Create a new special memory pool that can be used to manage special purpose
 615  * memory not managed by the regular kmalloc/kfree interface. The pool will be
 616  * automatically destroyed by the device management code.
 617  */
 618 struct gen_pool *devm_gen_pool_create(struct device *dev, int min_alloc_order,
 619                                       int nid, const char *name)
 620 {
 621         struct gen_pool **ptr, *pool;
 622         const char *pool_name = NULL;
 623
 624         /* Check that genpool to be created is uniquely addressed on device */
 625         if (gen_pool_get(dev, name))
 626                 return ERR_PTR(-EINVAL);
 627
 628         if (name) {
 629                 pool_name = kstrdup_const(name, GFP_KERNEL);
 630                 if (!pool_name)
 631                         return ERR_PTR(-ENOMEM);
 632         }
 633
 634         ptr = devres_alloc(devm_gen_pool_release, sizeof(*ptr), GFP_KERNEL);
 635         if (!ptr)
 636                 goto free_pool_name;
 637
 638         pool = gen_pool_create(min_alloc_order, nid);
 639         if (!pool)
 640                 goto free_devres;
 641
 642         *ptr = pool;
 643         pool->name = pool_name;
 644         devres_add(dev, ptr);
 645
 646         return pool;
 647
 648 free_devres:
 649         devres_free(ptr);
 650 free_pool_name:
 651         kfree_const(pool_name);
 652
 653         return ERR_PTR(-ENOMEM);
 654 }
 655 EXPORT_SYMBOL(devm_gen_pool_create);
 656
 657 #ifdef CONFIG_OF
 658 /**
 659  * of_gen_pool_get - find a pool by phandle property
 660  * @np: device node
 661  * @propname: property name containing phandle(s)
 662  * @index: index into the phandle array
 663  *
 664  * Returns the pool that contains the chunk starting at the physical
 665  * address of the device tree node pointed at by the phandle property,
 666  * or NULL if not found.
 667  */
 668 struct gen_pool *of_gen_pool_get(struct device_node *np,
 669         const char *propname, int index)
 670 {
 671         struct platform_device *pdev;
 672         struct device_node *np_pool, *parent;
 673         const char *name = NULL;
 674         struct gen_pool *pool = NULL;
 675
 676         np_pool = of_parse_phandle(np, propname, index);
 677         if (!np_pool)
 678                 return NULL;
 679
 680         pdev = of_find_device_by_node(np_pool);
 681         if (!pdev) {
 682                 /* Check if named gen_pool is created by parent node device */
 683                 parent = of_get_parent(np_pool);
 684                 pdev = of_find_device_by_node(parent);
 685                 of_node_put(parent);
 686
 687                 of_property_read_string(np_pool, "label", &name);
 688                 if (!name)
 689                         name = np_pool->name;
 690         }
 691         if (pdev)
 692                 pool = gen_pool_get(&pdev->dev, name);
 693         of_node_put(np_pool);
 694
 695         return pool;
 696 }
 697 EXPORT_SYMBOL_GPL(of_gen_pool_get);
 698 #endif /* CONFIG_OF */