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.
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
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.
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.
25 * Copyright 2005 (C) Jes Sorensen <jes@trained-monkey.org>
27 * This source code is licensed under the GNU General Public License,
28 * Version 2. See the file COPYING for more details.
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_address.h>
38 #include <linux/of_device.h>
40 static inline size_t chunk_size(const struct gen_pool_chunk
*chunk
)
42 return chunk
->end_addr
- chunk
->start_addr
+ 1;
45 static int set_bits_ll(unsigned long *addr
, unsigned long mask_to_set
)
47 unsigned long val
, nval
;
52 if (val
& mask_to_set
)
55 } while ((nval
= cmpxchg(addr
, val
, val
| mask_to_set
)) != val
);
60 static int clear_bits_ll(unsigned long *addr
, unsigned long mask_to_clear
)
62 unsigned long val
, nval
;
67 if ((val
& mask_to_clear
) != mask_to_clear
)
70 } while ((nval
= cmpxchg(addr
, val
, val
& ~mask_to_clear
)) != val
);
76 * bitmap_set_ll - set the specified number of bits at the specified position
77 * @map: pointer to a bitmap
78 * @start: a bit position in @map
79 * @nr: number of bits to set
81 * Set @nr bits start from @start in @map lock-lessly. Several users
82 * can set/clear the same bitmap simultaneously without lock. If two
83 * users set the same bit, one user will return remain bits, otherwise
86 static int bitmap_set_ll(unsigned long *map
, int start
, int nr
)
88 unsigned long *p
= map
+ BIT_WORD(start
);
89 const int size
= start
+ nr
;
90 int bits_to_set
= BITS_PER_LONG
- (start
% BITS_PER_LONG
);
91 unsigned long mask_to_set
= BITMAP_FIRST_WORD_MASK(start
);
93 while (nr
- bits_to_set
>= 0) {
94 if (set_bits_ll(p
, mask_to_set
))
97 bits_to_set
= BITS_PER_LONG
;
102 mask_to_set
&= BITMAP_LAST_WORD_MASK(size
);
103 if (set_bits_ll(p
, mask_to_set
))
111 * bitmap_clear_ll - clear the specified number of bits at the specified position
112 * @map: pointer to a bitmap
113 * @start: a bit position in @map
114 * @nr: number of bits to set
116 * Clear @nr bits start from @start in @map lock-lessly. Several users
117 * can set/clear the same bitmap simultaneously without lock. If two
118 * users clear the same bit, one user will return remain bits,
119 * otherwise return 0.
121 static int bitmap_clear_ll(unsigned long *map
, int start
, int nr
)
123 unsigned long *p
= map
+ BIT_WORD(start
);
124 const int size
= start
+ nr
;
125 int bits_to_clear
= BITS_PER_LONG
- (start
% BITS_PER_LONG
);
126 unsigned long mask_to_clear
= BITMAP_FIRST_WORD_MASK(start
);
128 while (nr
- bits_to_clear
>= 0) {
129 if (clear_bits_ll(p
, mask_to_clear
))
132 bits_to_clear
= BITS_PER_LONG
;
133 mask_to_clear
= ~0UL;
137 mask_to_clear
&= BITMAP_LAST_WORD_MASK(size
);
138 if (clear_bits_ll(p
, mask_to_clear
))
146 * gen_pool_create - create a new special memory pool
147 * @min_alloc_order: log base 2 of number of bytes each bitmap bit represents
148 * @nid: node id of the node the pool structure should be allocated on, or -1
150 * Create a new special memory pool that can be used to manage special purpose
151 * memory not managed by the regular kmalloc/kfree interface.
153 struct gen_pool
*gen_pool_create(int min_alloc_order
, int nid
)
155 struct gen_pool
*pool
;
157 pool
= kmalloc_node(sizeof(struct gen_pool
), GFP_KERNEL
, nid
);
159 spin_lock_init(&pool
->lock
);
160 INIT_LIST_HEAD(&pool
->chunks
);
161 pool
->min_alloc_order
= min_alloc_order
;
162 pool
->algo
= gen_pool_first_fit
;
167 EXPORT_SYMBOL(gen_pool_create
);
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
178 * Add a new chunk of special memory to the specified pool.
180 * Returns 0 on success or a -ve errno on failure.
182 int gen_pool_add_virt(struct gen_pool
*pool
, unsigned long virt
, phys_addr_t phys
,
183 size_t size
, int nid
)
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);
190 chunk
= kzalloc_node(nbytes
, GFP_KERNEL
, nid
);
191 if (unlikely(chunk
== NULL
))
194 chunk
->phys_addr
= phys
;
195 chunk
->start_addr
= virt
;
196 chunk
->end_addr
= virt
+ size
- 1;
197 atomic_set(&chunk
->avail
, size
);
199 spin_lock(&pool
->lock
);
200 list_add_rcu(&chunk
->next_chunk
, &pool
->chunks
);
201 spin_unlock(&pool
->lock
);
205 EXPORT_SYMBOL(gen_pool_add_virt
);
208 * gen_pool_virt_to_phys - return the physical address of memory
209 * @pool: pool to allocate from
210 * @addr: starting address of memory
212 * Returns the physical address on success, or -1 on error.
214 phys_addr_t
gen_pool_virt_to_phys(struct gen_pool
*pool
, unsigned long addr
)
216 struct gen_pool_chunk
*chunk
;
217 phys_addr_t paddr
= -1;
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
);
230 EXPORT_SYMBOL(gen_pool_virt_to_phys
);
233 * gen_pool_destroy - destroy a special memory pool
234 * @pool: pool to destroy
236 * Destroy the specified special memory pool. Verifies that there are no
237 * outstanding allocations.
239 void gen_pool_destroy(struct gen_pool
*pool
)
241 struct list_head
*_chunk
, *_next_chunk
;
242 struct gen_pool_chunk
*chunk
;
243 int order
= pool
->min_alloc_order
;
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
);
250 end_bit
= chunk_size(chunk
) >> order
;
251 bit
= find_next_bit(chunk
->bits
, end_bit
, 0);
252 BUG_ON(bit
< end_bit
);
259 EXPORT_SYMBOL(gen_pool_destroy
);
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
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.
271 unsigned long gen_pool_alloc(struct gen_pool
*pool
, size_t size
)
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
;
278 #ifndef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG
285 nbits
= (size
+ (1UL << order
) - 1) >> order
;
287 list_for_each_entry_rcu(chunk
, &pool
->chunks
, next_chunk
) {
288 if (size
> atomic_read(&chunk
->avail
))
291 end_bit
= chunk_size(chunk
) >> order
;
293 start_bit
= pool
->algo(chunk
->bits
, end_bit
, start_bit
, nbits
,
295 if (start_bit
>= end_bit
)
297 remain
= bitmap_set_ll(chunk
->bits
, start_bit
, nbits
);
299 remain
= bitmap_clear_ll(chunk
->bits
, start_bit
,
305 addr
= chunk
->start_addr
+ ((unsigned long)start_bit
<< order
);
306 size
= nbits
<< order
;
307 atomic_sub(size
, &chunk
->avail
);
313 EXPORT_SYMBOL(gen_pool_alloc
);
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.
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.
326 void *gen_pool_dma_alloc(struct gen_pool
*pool
, size_t size
, dma_addr_t
*dma
)
333 vaddr
= gen_pool_alloc(pool
, size
);
338 *dma
= gen_pool_virt_to_phys(pool
, vaddr
);
340 return (void *)vaddr
;
342 EXPORT_SYMBOL(gen_pool_dma_alloc
);
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
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.
354 void gen_pool_free(struct gen_pool
*pool
, unsigned long addr
, size_t size
)
356 struct gen_pool_chunk
*chunk
;
357 int order
= pool
->min_alloc_order
;
358 int start_bit
, nbits
, remain
;
360 #ifndef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG
364 nbits
= (size
+ (1UL << order
) - 1) >> order
;
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
);
372 size
= nbits
<< order
;
373 atomic_add(size
, &chunk
->avail
);
381 EXPORT_SYMBOL(gen_pool_free
);
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
389 * Call @func for every chunk of generic memory pool. The @func is
390 * called with rcu_read_lock held.
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
),
396 struct gen_pool_chunk
*chunk
;
399 list_for_each_entry_rcu(chunk
, &(pool
)->chunks
, next_chunk
)
400 func(pool
, chunk
, data
);
403 EXPORT_SYMBOL(gen_pool_for_each_chunk
);
406 * gen_pool_avail - get available free space of the pool
407 * @pool: pool to get available free space
409 * Return available free space of the specified pool.
411 size_t gen_pool_avail(struct gen_pool
*pool
)
413 struct gen_pool_chunk
*chunk
;
417 list_for_each_entry_rcu(chunk
, &pool
->chunks
, next_chunk
)
418 avail
+= atomic_read(&chunk
->avail
);
422 EXPORT_SYMBOL_GPL(gen_pool_avail
);
425 * gen_pool_size - get size in bytes of memory managed by the pool
426 * @pool: pool to get size
428 * Return size in bytes of memory managed by the pool.
430 size_t gen_pool_size(struct gen_pool
*pool
)
432 struct gen_pool_chunk
*chunk
;
436 list_for_each_entry_rcu(chunk
, &pool
->chunks
, next_chunk
)
437 size
+= chunk_size(chunk
);
441 EXPORT_SYMBOL_GPL(gen_pool_size
);
444 * gen_pool_set_algo - set the allocation algorithm
445 * @pool: pool to change allocation algorithm
446 * @algo: custom algorithm function
447 * @data: additional data used by @algo
449 * Call @algo for each memory allocation in the pool.
450 * If @algo is NULL use gen_pool_first_fit as default
451 * memory allocation function.
453 void gen_pool_set_algo(struct gen_pool
*pool
, genpool_algo_t algo
, void *data
)
459 pool
->algo
= gen_pool_first_fit
;
465 EXPORT_SYMBOL(gen_pool_set_algo
);
468 * gen_pool_first_fit - find the first available region
469 * of memory matching the size requirement (no alignment constraint)
470 * @map: The address to base the search on
471 * @size: The bitmap size in bits
472 * @start: The bitnumber to start searching at
473 * @nr: The number of zeroed bits we're looking for
474 * @data: additional data - unused
476 unsigned long gen_pool_first_fit(unsigned long *map
, unsigned long size
,
477 unsigned long start
, unsigned int nr
, void *data
)
479 return bitmap_find_next_zero_area(map
, size
, start
, nr
, 0);
481 EXPORT_SYMBOL(gen_pool_first_fit
);
484 * gen_pool_best_fit - find the best fitting region of memory
485 * macthing the size requirement (no alignment constraint)
486 * @map: The address to base the search on
487 * @size: The bitmap size in bits
488 * @start: The bitnumber to start searching at
489 * @nr: The number of zeroed bits we're looking for
490 * @data: additional data - unused
492 * Iterate over the bitmap to find the smallest free region
493 * which we can allocate the memory.
495 unsigned long gen_pool_best_fit(unsigned long *map
, unsigned long size
,
496 unsigned long start
, unsigned int nr
, void *data
)
498 unsigned long start_bit
= size
;
499 unsigned long len
= size
+ 1;
502 index
= bitmap_find_next_zero_area(map
, size
, start
, nr
, 0);
504 while (index
< size
) {
505 int next_bit
= find_next_bit(map
, size
, index
+ nr
);
506 if ((next_bit
- index
) < len
) {
507 len
= next_bit
- index
;
512 index
= bitmap_find_next_zero_area(map
, size
,
513 next_bit
+ 1, nr
, 0);
518 EXPORT_SYMBOL(gen_pool_best_fit
);
520 static void devm_gen_pool_release(struct device
*dev
, void *res
)
522 gen_pool_destroy(*(struct gen_pool
**)res
);
526 * devm_gen_pool_create - managed gen_pool_create
527 * @dev: device that provides the gen_pool
528 * @min_alloc_order: log base 2 of number of bytes each bitmap bit represents
529 * @nid: node id of the node the pool structure should be allocated on, or -1
531 * Create a new special memory pool that can be used to manage special purpose
532 * memory not managed by the regular kmalloc/kfree interface. The pool will be
533 * automatically destroyed by the device management code.
535 struct gen_pool
*devm_gen_pool_create(struct device
*dev
, int min_alloc_order
,
538 struct gen_pool
**ptr
, *pool
;
540 ptr
= devres_alloc(devm_gen_pool_release
, sizeof(*ptr
), GFP_KERNEL
);
542 pool
= gen_pool_create(min_alloc_order
, nid
);
545 devres_add(dev
, ptr
);
554 * dev_get_gen_pool - Obtain the gen_pool (if any) for a device
555 * @dev: device to retrieve the gen_pool from
557 * Returns the gen_pool for the device if one is present, or NULL.
559 struct gen_pool
*dev_get_gen_pool(struct device
*dev
)
561 struct gen_pool
**p
= devres_find(dev
, devm_gen_pool_release
, NULL
,
568 EXPORT_SYMBOL_GPL(dev_get_gen_pool
);
572 * of_get_named_gen_pool - find a pool by phandle property
574 * @propname: property name containing phandle(s)
575 * @index: index into the phandle array
577 * Returns the pool that contains the chunk starting at the physical
578 * address of the device tree node pointed at by the phandle property,
579 * or NULL if not found.
581 struct gen_pool
*of_get_named_gen_pool(struct device_node
*np
,
582 const char *propname
, int index
)
584 struct platform_device
*pdev
;
585 struct device_node
*np_pool
;
587 np_pool
= of_parse_phandle(np
, propname
, index
);
590 pdev
= of_find_device_by_node(np_pool
);
591 of_node_put(np_pool
);
594 return dev_get_gen_pool(&pdev
->dev
);
596 EXPORT_SYMBOL_GPL(of_get_named_gen_pool
);
597 #endif /* CONFIG_OF */
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