lib/genalloc.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Basic general purpose allocator for managing special purpose
   4  * memory, for example, memory that is not managed by the regular
   5  * kmalloc/kfree interface.  Uses for this includes on-device special
   6  * memory, uncached memory etc.
   7  *
   8  * It is safe to use the allocator in NMI handlers and other special
   9  * unblockable contexts that could otherwise deadlock on locks.  This
  10  * is implemented by using atomic operations and retries on any
  11  * conflicts.  The disadvantage is that there may be livelocks in
  12  * extreme cases.  For better scalability, one allocator can be used
  13  * for each CPU.
  14  *
  15  * The lockless operation only works if there is enough memory
  16  * available.  If new memory is added to the pool a lock has to be
  17  * still taken.  So any user relying on locklessness has to ensure
  18  * that sufficient memory is preallocated.
  19  *
  20  * The basic atomic operation of this allocator is cmpxchg on long.
  21  * On architectures that don't have NMI-safe cmpxchg implementation,
  22  * the allocator can NOT be used in NMI handler.  So code uses the
  23  * allocator in NMI handler should depend on
  24  * CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG.
  25  *
  26  * Copyright 2005 (C) Jes Sorensen <jes@trained-monkey.org>
  27  */
  28
  29 #include <linux/slab.h>
  30 #include <linux/export.h>
  31 #include <linux/bitmap.h>
  32 #include <linux/rculist.h>
  33 #include <linux/interrupt.h>
  34 #include <linux/genalloc.h>
  35 #include <linux/of_device.h>
  36 #include <linux/vmalloc.h>
  37
  38 static inline size_t chunk_size(const struct gen_pool_chunk *chunk)
  39 {
  40         return chunk->end_addr - chunk->start_addr + 1;
  41 }
  42
  43 static int set_bits_ll(unsigned long *addr, unsigned long mask_to_set)
  44 {
  45         unsigned long val, nval;
  46
  47         nval = *addr;
  48         do {
  49                 val = nval;
  50                 if (val & mask_to_set)
  51                         return -EBUSY;
  52                 cpu_relax();
  53         } while ((nval = cmpxchg(addr, val, val | mask_to_set)) != val);
  54
  55         return 0;
  56 }
  57
  58 static int clear_bits_ll(unsigned long *addr, unsigned long mask_to_clear)
  59 {
  60         unsigned long val, nval;
  61
  62         nval = *addr;
  63         do {
  64                 val = nval;
  65                 if ((val & mask_to_clear) != mask_to_clear)
  66                         return -EBUSY;
  67                 cpu_relax();
  68         } while ((nval = cmpxchg(addr, val, val & ~mask_to_clear)) != val);
  69
  70         return 0;
  71 }
  72
  73 /*
  74  * bitmap_set_ll - set the specified number of bits at the specified position
  75  * @map: pointer to a bitmap
  76  * @start: a bit position in @map
  77  * @nr: number of bits to set
  78  *
  79  * Set @nr bits start from @start in @map lock-lessly. Several users
  80  * can set/clear the same bitmap simultaneously without lock. If two
  81  * users set the same bit, one user will return remain bits, otherwise
  82  * return 0.
  83  */
  84 static int bitmap_set_ll(unsigned long *map, unsigned long start, unsigned long nr)
  85 {
  86         unsigned long *p = map + BIT_WORD(start);
  87         const unsigned long size = start + nr;
  88         int bits_to_set = BITS_PER_LONG - (start % BITS_PER_LONG);
  89         unsigned long mask_to_set = BITMAP_FIRST_WORD_MASK(start);
  90
  91         while (nr >= bits_to_set) {
  92                 if (set_bits_ll(p, mask_to_set))
  93                         return nr;
  94                 nr -= bits_to_set;
  95                 bits_to_set = BITS_PER_LONG;
  96                 mask_to_set = ~0UL;
  97                 p++;
  98         }
  99         if (nr) {
 100                 mask_to_set &= BITMAP_LAST_WORD_MASK(size);
 101                 if (set_bits_ll(p, mask_to_set))
 102                         return nr;
 103         }
 104
 105         return 0;
 106 }
 107
 108 /*
 109  * bitmap_clear_ll - clear the specified number of bits at the specified position
 110  * @map: pointer to a bitmap
 111  * @start: a bit position in @map
 112  * @nr: number of bits to set
 113  *
 114  * Clear @nr bits start from @start in @map lock-lessly. Several users
 115  * can set/clear the same bitmap simultaneously without lock. If two
 116  * users clear the same bit, one user will return remain bits,
 117  * otherwise return 0.
 118  */
 119 static unsigned long
 120 bitmap_clear_ll(unsigned long *map, unsigned long start, unsigned long nr)
 121 {
 122         unsigned long *p = map + BIT_WORD(start);
 123         const unsigned long 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) {
 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_owner- 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  * @owner: private data the publisher would like to recall at alloc time
 178  *
 179  * Add a new chunk of special memory to the specified pool.
 180  *
 181  * Returns 0 on success or a -ve errno on failure.
 182  */
 183 int gen_pool_add_owner(struct gen_pool *pool, unsigned long virt, phys_addr_t phys,
 184                  size_t size, int nid, void *owner)
 185 {
 186         struct gen_pool_chunk *chunk;
 187         unsigned long nbits = size >> pool->min_alloc_order;
 188         unsigned long nbytes = sizeof(struct gen_pool_chunk) +
 189                                 BITS_TO_LONGS(nbits) * sizeof(long);
 190
 191         chunk = vzalloc_node(nbytes, nid);
 192         if (unlikely(chunk == NULL))
 193                 return -ENOMEM;
 194
 195         chunk->phys_addr = phys;
 196         chunk->start_addr = virt;
 197         chunk->end_addr = virt + size - 1;
 198         chunk->owner = owner;
 199         atomic_long_set(&chunk->avail, size);
 200
 201         spin_lock(&pool->lock);
 202         list_add_rcu(&chunk->next_chunk, &pool->chunks);
 203         spin_unlock(&pool->lock);
 204
 205         return 0;
 206 }
 207 EXPORT_SYMBOL(gen_pool_add_owner);
 208
 209 /**
 210  * gen_pool_virt_to_phys - return the physical address of memory
 211  * @pool: pool to allocate from
 212  * @addr: starting address of memory
 213  *
 214  * Returns the physical address on success, or -1 on error.
 215  */
 216 phys_addr_t gen_pool_virt_to_phys(struct gen_pool *pool, unsigned long addr)
 217 {
 218         struct gen_pool_chunk *chunk;
 219         phys_addr_t paddr = -1;
 220
 221         rcu_read_lock();
 222         list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk) {
 223                 if (addr >= chunk->start_addr && addr <= chunk->end_addr) {
 224                         paddr = chunk->phys_addr + (addr - chunk->start_addr);
 225                         break;
 226                 }
 227         }
 228         rcu_read_unlock();
 229
 230         return paddr;
 231 }
 232 EXPORT_SYMBOL(gen_pool_virt_to_phys);
 233
 234 /**
 235  * gen_pool_destroy - destroy a special memory pool
 236  * @pool: pool to destroy
 237  *
 238  * Destroy the specified special memory pool. Verifies that there are no
 239  * outstanding allocations.
 240  */
 241 void gen_pool_destroy(struct gen_pool *pool)
 242 {
 243         struct list_head *_chunk, *_next_chunk;
 244         struct gen_pool_chunk *chunk;
 245         int order = pool->min_alloc_order;
 246         unsigned long bit, end_bit;
 247
 248         list_for_each_safe(_chunk, _next_chunk, &pool->chunks) {
 249                 chunk = list_entry(_chunk, struct gen_pool_chunk, next_chunk);
 250                 list_del(&chunk->next_chunk);
 251
 252                 end_bit = chunk_size(chunk) >> order;
 253                 bit = find_next_bit(chunk->bits, end_bit, 0);
 254                 BUG_ON(bit < end_bit);
 255
 256                 vfree(chunk);
 257         }
 258         kfree_const(pool->name);
 259         kfree(pool);
 260 }
 261 EXPORT_SYMBOL(gen_pool_destroy);
 262
 263 /**
 264  * gen_pool_alloc_algo_owner - allocate special memory from the pool
 265  * @pool: pool to allocate from
 266  * @size: number of bytes to allocate from the pool
 267  * @algo: algorithm passed from caller
 268  * @data: data passed to algorithm
 269  * @owner: optionally retrieve the chunk owner
 270  *
 271  * Allocate the requested number of bytes from the specified pool.
 272  * Uses the pool allocation function (with first-fit algorithm by default).
 273  * Can not be used in NMI handler on architectures without
 274  * NMI-safe cmpxchg implementation.
 275  */
 276 unsigned long gen_pool_alloc_algo_owner(struct gen_pool *pool, size_t size,
 277                 genpool_algo_t algo, void *data, void **owner)
 278 {
 279         struct gen_pool_chunk *chunk;
 280         unsigned long addr = 0;
 281         int order = pool->min_alloc_order;
 282         unsigned long nbits, start_bit, end_bit, remain;
 283
 284 #ifndef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG
 285         BUG_ON(in_nmi());
 286 #endif
 287
 288         if (owner)
 289                 *owner = NULL;
 290
 291         if (size == 0)
 292                 return 0;
 293
 294         nbits = (size + (1UL << order) - 1) >> order;
 295         rcu_read_lock();
 296         list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk) {
 297                 if (size > atomic_long_read(&chunk->avail))
 298                         continue;
 299
 300                 start_bit = 0;
 301                 end_bit = chunk_size(chunk) >> order;
 302 retry:
 303                 start_bit = algo(chunk->bits, end_bit, start_bit,
 304                                  nbits, data, pool, chunk->start_addr);
 305                 if (start_bit >= end_bit)
 306                         continue;
 307                 remain = bitmap_set_ll(chunk->bits, start_bit, nbits);
 308                 if (remain) {
 309                         remain = bitmap_clear_ll(chunk->bits, start_bit,
 310                                                  nbits - remain);
 311                         BUG_ON(remain);
 312                         goto retry;
 313                 }
 314
 315                 addr = chunk->start_addr + ((unsigned long)start_bit << order);
 316                 size = nbits << order;
 317                 atomic_long_sub(size, &chunk->avail);
 318                 if (owner)
 319                         *owner = chunk->owner;
 320                 break;
 321         }
 322         rcu_read_unlock();
 323         return addr;
 324 }
 325 EXPORT_SYMBOL(gen_pool_alloc_algo_owner);
 326
 327 /**
 328  * gen_pool_dma_alloc - allocate special memory from the pool for DMA usage
 329  * @pool: pool to allocate from
 330  * @size: number of bytes to allocate from the pool
 331  * @dma: dma-view physical address return value.  Use %NULL if unneeded.
 332  *
 333  * Allocate the requested number of bytes from the specified pool.
 334  * Uses the pool allocation function (with first-fit algorithm by default).
 335  * Can not be used in NMI handler on architectures without
 336  * NMI-safe cmpxchg implementation.
 337  *
 338  * Return: virtual address of the allocated memory, or %NULL on failure
 339  */
 340 void *gen_pool_dma_alloc(struct gen_pool *pool, size_t size, dma_addr_t *dma)
 341 {
 342         return gen_pool_dma_alloc_algo(pool, size, dma, pool->algo, pool->data);
 343 }
 344 EXPORT_SYMBOL(gen_pool_dma_alloc);
 345
 346 /**
 347  * gen_pool_dma_alloc_algo - allocate special memory from the pool for DMA
 348  * usage with the given pool algorithm
 349  * @pool: pool to allocate from
 350  * @size: number of bytes to allocate from the pool
 351  * @dma: DMA-view physical address return value. Use %NULL if unneeded.
 352  * @algo: algorithm passed from caller
 353  * @data: data passed to algorithm
 354  *
 355  * Allocate the requested number of bytes from the specified pool. Uses the
 356  * given pool allocation function. Can not be used in NMI handler on
 357  * architectures without NMI-safe cmpxchg implementation.
 358  *
 359  * Return: virtual address of the allocated memory, or %NULL on failure
 360  */
 361 void *gen_pool_dma_alloc_algo(struct gen_pool *pool, size_t size,
 362                 dma_addr_t *dma, genpool_algo_t algo, void *data)
 363 {
 364         unsigned long vaddr;
 365
 366         if (!pool)
 367                 return NULL;
 368
 369         vaddr = gen_pool_alloc_algo(pool, size, algo, data);
 370         if (!vaddr)
 371                 return NULL;
 372
 373         if (dma)
 374                 *dma = gen_pool_virt_to_phys(pool, vaddr);
 375
 376         return (void *)vaddr;
 377 }
 378 EXPORT_SYMBOL(gen_pool_dma_alloc_algo);
 379
 380 /**
 381  * gen_pool_dma_alloc_align - allocate special memory from the pool for DMA
 382  * usage with the given alignment
 383  * @pool: pool to allocate from
 384  * @size: number of bytes to allocate from the pool
 385  * @dma: DMA-view physical address return value. Use %NULL if unneeded.
 386  * @align: alignment in bytes for starting address
 387  *
 388  * Allocate the requested number bytes from the specified pool, with the given
 389  * alignment restriction. Can not be used in NMI handler on architectures
 390  * without NMI-safe cmpxchg implementation.
 391  *
 392  * Return: virtual address of the allocated memory, or %NULL on failure
 393  */
 394 void *gen_pool_dma_alloc_align(struct gen_pool *pool, size_t size,
 395                 dma_addr_t *dma, int align)
 396 {
 397         struct genpool_data_align data = { .align = align };
 398
 399         return gen_pool_dma_alloc_algo(pool, size, dma,
 400                         gen_pool_first_fit_align, &data);
 401 }
 402 EXPORT_SYMBOL(gen_pool_dma_alloc_align);
 403
 404 /**
 405  * gen_pool_dma_zalloc - allocate special zeroed memory from the pool for
 406  * DMA usage
 407  * @pool: pool to allocate from
 408  * @size: number of bytes to allocate from the pool
 409  * @dma: dma-view physical address return value.  Use %NULL if unneeded.
 410  *
 411  * Allocate the requested number of zeroed bytes from the specified pool.
 412  * Uses the pool allocation function (with first-fit algorithm by default).
 413  * Can not be used in NMI handler on architectures without
 414  * NMI-safe cmpxchg implementation.
 415  *
 416  * Return: virtual address of the allocated zeroed memory, or %NULL on failure
 417  */
 418 void *gen_pool_dma_zalloc(struct gen_pool *pool, size_t size, dma_addr_t *dma)
 419 {
 420         return gen_pool_dma_zalloc_algo(pool, size, dma, pool->algo, pool->data);
 421 }
 422 EXPORT_SYMBOL(gen_pool_dma_zalloc);
 423
 424 /**
 425  * gen_pool_dma_zalloc_algo - allocate special zeroed memory from the pool for
 426  * DMA usage with the given pool algorithm
 427  * @pool: pool to allocate from
 428  * @size: number of bytes to allocate from the pool
 429  * @dma: DMA-view physical address return value. Use %NULL if unneeded.
 430  * @algo: algorithm passed from caller
 431  * @data: data passed to algorithm
 432  *
 433  * Allocate the requested number of zeroed bytes from the specified pool. Uses
 434  * the given pool allocation function. Can not be used in NMI handler on
 435  * architectures without NMI-safe cmpxchg implementation.
 436  *
 437  * Return: virtual address of the allocated zeroed memory, or %NULL on failure
 438  */
 439 void *gen_pool_dma_zalloc_algo(struct gen_pool *pool, size_t size,
 440                 dma_addr_t *dma, genpool_algo_t algo, void *data)
 441 {
 442         void *vaddr = gen_pool_dma_alloc_algo(pool, size, dma, algo, data);
 443
 444         if (vaddr)
 445                 memset(vaddr, 0, size);
 446
 447         return vaddr;
 448 }
 449 EXPORT_SYMBOL(gen_pool_dma_zalloc_algo);
 450
 451 /**
 452  * gen_pool_dma_zalloc_align - allocate special zeroed memory from the pool for
 453  * DMA usage with the given alignment
 454  * @pool: pool to allocate from
 455  * @size: number of bytes to allocate from the pool
 456  * @dma: DMA-view physical address return value. Use %NULL if unneeded.
 457  * @align: alignment in bytes for starting address
 458  *
 459  * Allocate the requested number of zeroed bytes from the specified pool,
 460  * with the given alignment restriction. Can not be used in NMI handler on
 461  * architectures without NMI-safe cmpxchg implementation.
 462  *
 463  * Return: virtual address of the allocated zeroed memory, or %NULL on failure
 464  */
 465 void *gen_pool_dma_zalloc_align(struct gen_pool *pool, size_t size,
 466                 dma_addr_t *dma, int align)
 467 {
 468         struct genpool_data_align data = { .align = align };
 469
 470         return gen_pool_dma_zalloc_algo(pool, size, dma,
 471                         gen_pool_first_fit_align, &data);
 472 }
 473 EXPORT_SYMBOL(gen_pool_dma_zalloc_align);
 474
 475 /**
 476  * gen_pool_free_owner - free allocated special memory back to the pool
 477  * @pool: pool to free to
 478  * @addr: starting address of memory to free back to pool
 479  * @size: size in bytes of memory to free
 480  * @owner: private data stashed at gen_pool_add() time
 481  *
 482  * Free previously allocated special memory back to the specified
 483  * pool.  Can not be used in NMI handler on architectures without
 484  * NMI-safe cmpxchg implementation.
 485  */
 486 void gen_pool_free_owner(struct gen_pool *pool, unsigned long addr, size_t size,
 487                 void **owner)
 488 {
 489         struct gen_pool_chunk *chunk;
 490         int order = pool->min_alloc_order;
 491         unsigned long start_bit, nbits, remain;
 492
 493 #ifndef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG
 494         BUG_ON(in_nmi());
 495 #endif
 496
 497         if (owner)
 498                 *owner = NULL;
 499
 500         nbits = (size + (1UL << order) - 1) >> order;
 501         rcu_read_lock();
 502         list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk) {
 503                 if (addr >= chunk->start_addr && addr <= chunk->end_addr) {
 504                         BUG_ON(addr + size - 1 > chunk->end_addr);
 505                         start_bit = (addr - chunk->start_addr) >> order;
 506                         remain = bitmap_clear_ll(chunk->bits, start_bit, nbits);
 507                         BUG_ON(remain);
 508                         size = nbits << order;
 509                         atomic_long_add(size, &chunk->avail);
 510                         if (owner)
 511                                 *owner = chunk->owner;
 512                         rcu_read_unlock();
 513                         return;
 514                 }
 515         }
 516         rcu_read_unlock();
 517         BUG();
 518 }
 519 EXPORT_SYMBOL(gen_pool_free_owner);
 520
 521 /**
 522  * gen_pool_for_each_chunk - call func for every chunk of generic memory pool
 523  * @pool:       the generic memory pool
 524  * @func:       func to call
 525  * @data:       additional data used by @func
 526  *
 527  * Call @func for every chunk of generic memory pool.  The @func is
 528  * called with rcu_read_lock held.
 529  */
 530 void gen_pool_for_each_chunk(struct gen_pool *pool,
 531         void (*func)(struct gen_pool *pool, struct gen_pool_chunk *chunk, void *data),
 532         void *data)
 533 {
 534         struct gen_pool_chunk *chunk;
 535
 536         rcu_read_lock();
 537         list_for_each_entry_rcu(chunk, &(pool)->chunks, next_chunk)
 538                 func(pool, chunk, data);
 539         rcu_read_unlock();
 540 }
 541 EXPORT_SYMBOL(gen_pool_for_each_chunk);
 542
 543 /**
 544  * gen_pool_has_addr - checks if an address falls within the range of a pool
 545  * @pool:       the generic memory pool
 546  * @start:      start address
 547  * @size:       size of the region
 548  *
 549  * Check if the range of addresses falls within the specified pool. Returns
 550  * true if the entire range is contained in the pool and false otherwise.
 551  */
 552 bool gen_pool_has_addr(struct gen_pool *pool, unsigned long start,
 553                         size_t size)
 554 {
 555         bool found = false;
 556         unsigned long end = start + size - 1;
 557         struct gen_pool_chunk *chunk;
 558
 559         rcu_read_lock();
 560         list_for_each_entry_rcu(chunk, &(pool)->chunks, next_chunk) {
 561                 if (start >= chunk->start_addr && start <= chunk->end_addr) {
 562                         if (end <= chunk->end_addr) {
 563                                 found = true;
 564                                 break;
 565                         }
 566                 }
 567         }
 568         rcu_read_unlock();
 569         return found;
 570 }
 571 EXPORT_SYMBOL(gen_pool_has_addr);
 572
 573 /**
 574  * gen_pool_avail - get available free space of the pool
 575  * @pool: pool to get available free space
 576  *
 577  * Return available free space of the specified pool.
 578  */
 579 size_t gen_pool_avail(struct gen_pool *pool)
 580 {
 581         struct gen_pool_chunk *chunk;
 582         size_t avail = 0;
 583
 584         rcu_read_lock();
 585         list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk)
 586                 avail += atomic_long_read(&chunk->avail);
 587         rcu_read_unlock();
 588         return avail;
 589 }
 590 EXPORT_SYMBOL_GPL(gen_pool_avail);
 591
 592 /**
 593  * gen_pool_size - get size in bytes of memory managed by the pool
 594  * @pool: pool to get size
 595  *
 596  * Return size in bytes of memory managed by the pool.
 597  */
 598 size_t gen_pool_size(struct gen_pool *pool)
 599 {
 600         struct gen_pool_chunk *chunk;
 601         size_t size = 0;
 602
 603         rcu_read_lock();
 604         list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk)
 605                 size += chunk_size(chunk);
 606         rcu_read_unlock();
 607         return size;
 608 }
 609 EXPORT_SYMBOL_GPL(gen_pool_size);
 610
 611 /**
 612  * gen_pool_set_algo - set the allocation algorithm
 613  * @pool: pool to change allocation algorithm
 614  * @algo: custom algorithm function
 615  * @data: additional data used by @algo
 616  *
 617  * Call @algo for each memory allocation in the pool.
 618  * If @algo is NULL use gen_pool_first_fit as default
 619  * memory allocation function.
 620  */
 621 void gen_pool_set_algo(struct gen_pool *pool, genpool_algo_t algo, void *data)
 622 {
 623         rcu_read_lock();
 624
 625         pool->algo = algo;
 626         if (!pool->algo)
 627                 pool->algo = gen_pool_first_fit;
 628
 629         pool->data = data;
 630
 631         rcu_read_unlock();
 632 }
 633 EXPORT_SYMBOL(gen_pool_set_algo);
 634
 635 /**
 636  * gen_pool_first_fit - find the first available region
 637  * of memory matching the size requirement (no alignment constraint)
 638  * @map: The address to base the search on
 639  * @size: The bitmap size in bits
 640  * @start: The bitnumber to start searching at
 641  * @nr: The number of zeroed bits we're looking for
 642  * @data: additional data - unused
 643  * @pool: pool to find the fit region memory from
 644  */
 645 unsigned long gen_pool_first_fit(unsigned long *map, unsigned long size,
 646                 unsigned long start, unsigned int nr, void *data,
 647                 struct gen_pool *pool, unsigned long start_addr)
 648 {
 649         return bitmap_find_next_zero_area(map, size, start, nr, 0);
 650 }
 651 EXPORT_SYMBOL(gen_pool_first_fit);
 652
 653 /**
 654  * gen_pool_first_fit_align - find the first available region
 655  * of memory matching the size requirement (alignment constraint)
 656  * @map: The address to base the search on
 657  * @size: The bitmap size in bits
 658  * @start: The bitnumber to start searching at
 659  * @nr: The number of zeroed bits we're looking for
 660  * @data: data for alignment
 661  * @pool: pool to get order from
 662  */
 663 unsigned long gen_pool_first_fit_align(unsigned long *map, unsigned long size,
 664                 unsigned long start, unsigned int nr, void *data,
 665                 struct gen_pool *pool, unsigned long start_addr)
 666 {
 667         struct genpool_data_align *alignment;
 668         unsigned long align_mask, align_off;
 669         int order;
 670
 671         alignment = data;
 672         order = pool->min_alloc_order;
 673         align_mask = ((alignment->align + (1UL << order) - 1) >> order) - 1;
 674         align_off = (start_addr & (alignment->align - 1)) >> order;
 675
 676         return bitmap_find_next_zero_area_off(map, size, start, nr,
 677                                               align_mask, align_off);
 678 }
 679 EXPORT_SYMBOL(gen_pool_first_fit_align);
 680
 681 /**
 682  * gen_pool_fixed_alloc - reserve a specific region
 683  * @map: The address to base the search on
 684  * @size: The bitmap size in bits
 685  * @start: The bitnumber to start searching at
 686  * @nr: The number of zeroed bits we're looking for
 687  * @data: data for alignment
 688  * @pool: pool to get order from
 689  */
 690 unsigned long gen_pool_fixed_alloc(unsigned long *map, unsigned long size,
 691                 unsigned long start, unsigned int nr, void *data,
 692                 struct gen_pool *pool, unsigned long start_addr)
 693 {
 694         struct genpool_data_fixed *fixed_data;
 695         int order;
 696         unsigned long offset_bit;
 697         unsigned long start_bit;
 698
 699         fixed_data = data;
 700         order = pool->min_alloc_order;
 701         offset_bit = fixed_data->offset >> order;
 702         if (WARN_ON(fixed_data->offset & ((1UL << order) - 1)))
 703                 return size;
 704
 705         start_bit = bitmap_find_next_zero_area(map, size,
 706                         start + offset_bit, nr, 0);
 707         if (start_bit != offset_bit)
 708                 start_bit = size;
 709         return start_bit;
 710 }
 711 EXPORT_SYMBOL(gen_pool_fixed_alloc);
 712
 713 /**
 714  * gen_pool_first_fit_order_align - find the first available region
 715  * of memory matching the size requirement. The region will be aligned
 716  * to the order of the size specified.
 717  * @map: The address to base the search on
 718  * @size: The bitmap size in bits
 719  * @start: The bitnumber to start searching at
 720  * @nr: The number of zeroed bits we're looking for
 721  * @data: additional data - unused
 722  * @pool: pool to find the fit region memory from
 723  */
 724 unsigned long gen_pool_first_fit_order_align(unsigned long *map,
 725                 unsigned long size, unsigned long start,
 726                 unsigned int nr, void *data, struct gen_pool *pool,
 727                 unsigned long start_addr)
 728 {
 729         unsigned long align_mask = roundup_pow_of_two(nr) - 1;
 730
 731         return bitmap_find_next_zero_area(map, size, start, nr, align_mask);
 732 }
 733 EXPORT_SYMBOL(gen_pool_first_fit_order_align);
 734
 735 /**
 736  * gen_pool_best_fit - find the best fitting region of memory
 737  * macthing the size requirement (no alignment constraint)
 738  * @map: The address to base the search on
 739  * @size: The bitmap size in bits
 740  * @start: The bitnumber to start searching at
 741  * @nr: The number of zeroed bits we're looking for
 742  * @data: additional data - unused
 743  * @pool: pool to find the fit region memory from
 744  *
 745  * Iterate over the bitmap to find the smallest free region
 746  * which we can allocate the memory.
 747  */
 748 unsigned long gen_pool_best_fit(unsigned long *map, unsigned long size,
 749                 unsigned long start, unsigned int nr, void *data,
 750                 struct gen_pool *pool, unsigned long start_addr)
 751 {
 752         unsigned long start_bit = size;
 753         unsigned long len = size + 1;
 754         unsigned long index;
 755
 756         index = bitmap_find_next_zero_area(map, size, start, nr, 0);
 757
 758         while (index < size) {
 759                 unsigned long next_bit = find_next_bit(map, size, index + nr);
 760                 if ((next_bit - index) < len) {
 761                         len = next_bit - index;
 762                         start_bit = index;
 763                         if (len == nr)
 764                                 return start_bit;
 765                 }
 766                 index = bitmap_find_next_zero_area(map, size,
 767                                                    next_bit + 1, nr, 0);
 768         }
 769
 770         return start_bit;
 771 }
 772 EXPORT_SYMBOL(gen_pool_best_fit);
 773
 774 static void devm_gen_pool_release(struct device *dev, void *res)
 775 {
 776         gen_pool_destroy(*(struct gen_pool **)res);
 777 }
 778
 779 static int devm_gen_pool_match(struct device *dev, void *res, void *data)
 780 {
 781         struct gen_pool **p = res;
 782
 783         /* NULL data matches only a pool without an assigned name */
 784         if (!data && !(*p)->name)
 785                 return 1;
 786
 787         if (!data || !(*p)->name)
 788                 return 0;
 789
 790         return !strcmp((*p)->name, data);
 791 }
 792
 793 /**
 794  * gen_pool_get - Obtain the gen_pool (if any) for a device
 795  * @dev: device to retrieve the gen_pool from
 796  * @name: name of a gen_pool or NULL, identifies a particular gen_pool on device
 797  *
 798  * Returns the gen_pool for the device if one is present, or NULL.
 799  */
 800 struct gen_pool *gen_pool_get(struct device *dev, const char *name)
 801 {
 802         struct gen_pool **p;
 803
 804         p = devres_find(dev, devm_gen_pool_release, devm_gen_pool_match,
 805                         (void *)name);
 806         if (!p)
 807                 return NULL;
 808         return *p;
 809 }
 810 EXPORT_SYMBOL_GPL(gen_pool_get);
 811
 812 /**
 813  * devm_gen_pool_create - managed gen_pool_create
 814  * @dev: device that provides the gen_pool
 815  * @min_alloc_order: log base 2 of number of bytes each bitmap bit represents
 816  * @nid: node selector for allocated gen_pool, %NUMA_NO_NODE for all nodes
 817  * @name: name of a gen_pool or NULL, identifies a particular gen_pool on device
 818  *
 819  * Create a new special memory pool that can be used to manage special purpose
 820  * memory not managed by the regular kmalloc/kfree interface. The pool will be
 821  * automatically destroyed by the device management code.
 822  */
 823 struct gen_pool *devm_gen_pool_create(struct device *dev, int min_alloc_order,
 824                                       int nid, const char *name)
 825 {
 826         struct gen_pool **ptr, *pool;
 827         const char *pool_name = NULL;
 828
 829         /* Check that genpool to be created is uniquely addressed on device */
 830         if (gen_pool_get(dev, name))
 831                 return ERR_PTR(-EINVAL);
 832
 833         if (name) {
 834                 pool_name = kstrdup_const(name, GFP_KERNEL);
 835                 if (!pool_name)
 836                         return ERR_PTR(-ENOMEM);
 837         }
 838
 839         ptr = devres_alloc(devm_gen_pool_release, sizeof(*ptr), GFP_KERNEL);
 840         if (!ptr)
 841                 goto free_pool_name;
 842
 843         pool = gen_pool_create(min_alloc_order, nid);
 844         if (!pool)
 845                 goto free_devres;
 846
 847         *ptr = pool;
 848         pool->name = pool_name;
 849         devres_add(dev, ptr);
 850
 851         return pool;
 852
 853 free_devres:
 854         devres_free(ptr);
 855 free_pool_name:
 856         kfree_const(pool_name);
 857
 858         return ERR_PTR(-ENOMEM);
 859 }
 860 EXPORT_SYMBOL(devm_gen_pool_create);
 861
 862 #ifdef CONFIG_OF
 863 /**
 864  * of_gen_pool_get - find a pool by phandle property
 865  * @np: device node
 866  * @propname: property name containing phandle(s)
 867  * @index: index into the phandle array
 868  *
 869  * Returns the pool that contains the chunk starting at the physical
 870  * address of the device tree node pointed at by the phandle property,
 871  * or NULL if not found.
 872  */
 873 struct gen_pool *of_gen_pool_get(struct device_node *np,
 874         const char *propname, int index)
 875 {
 876         struct platform_device *pdev;
 877         struct device_node *np_pool, *parent;
 878         const char *name = NULL;
 879         struct gen_pool *pool = NULL;
 880
 881         np_pool = of_parse_phandle(np, propname, index);
 882         if (!np_pool)
 883                 return NULL;
 884
 885         pdev = of_find_device_by_node(np_pool);
 886         if (!pdev) {
 887                 /* Check if named gen_pool is created by parent node device */
 888                 parent = of_get_parent(np_pool);
 889                 pdev = of_find_device_by_node(parent);
 890                 of_node_put(parent);
 891
 892                 of_property_read_string(np_pool, "label", &name);
 893                 if (!name)
 894                         name = np_pool->name;
 895         }
 896         if (pdev)
 897                 pool = gen_pool_get(&pdev->dev, name);
 898         of_node_put(np_pool);
 899
 900         return pool;
 901 }
 902 EXPORT_SYMBOL_GPL(of_gen_pool_get);
 903 #endif /* CONFIG_OF */