4 * Copyright 2001 David Brownell
5 * Copyright 2007 Intel Corporation
6 * Author: Matthew Wilcox <willy@linux.intel.com>
8 * This software may be redistributed and/or modified under the terms of
9 * the GNU General Public License ("GPL") version 2 as published by the
10 * Free Software Foundation.
12 * This allocator returns small blocks of a given size which are DMA-able by
13 * the given device. It uses the dma_alloc_coherent page allocator to get
14 * new pages, then splits them up into blocks of the required size.
15 * Many older drivers still have their own code to do this.
17 * The current design of this allocator is fairly simple. The pool is
18 * represented by the 'struct dma_pool' which keeps a doubly-linked list of
19 * allocated pages. Each page in the page_list is split into blocks of at
20 * least 'size' bytes. Free blocks are tracked in an unsorted singly-linked
21 * list of free blocks within the page. Used blocks aren't tracked, but we
22 * keep a count of how many are currently allocated from each page.
25 #include <linux/device.h>
26 #include <linux/dma-mapping.h>
27 #include <linux/dmapool.h>
28 #include <linux/kernel.h>
29 #include <linux/list.h>
30 #include <linux/export.h>
31 #include <linux/mutex.h>
32 #include <linux/poison.h>
33 #include <linux/sched.h>
34 #include <linux/slab.h>
35 #include <linux/stat.h>
36 #include <linux/spinlock.h>
37 #include <linux/string.h>
38 #include <linux/types.h>
39 #include <linux/wait.h>
41 #if defined(CONFIG_DEBUG_SLAB) || defined(CONFIG_SLUB_DEBUG_ON)
42 #define DMAPOOL_DEBUG 1
45 struct dma_pool
{ /* the pool */
46 struct list_head page_list
;
53 struct list_head pools
;
56 struct dma_page
{ /* cacheable header for 'allocation' bytes */
57 struct list_head page_list
;
64 static DEFINE_MUTEX(pools_lock
);
67 show_pools(struct device
*dev
, struct device_attribute
*attr
, char *buf
)
72 struct dma_page
*page
;
73 struct dma_pool
*pool
;
78 temp
= scnprintf(next
, size
, "poolinfo - 0.1\n");
82 mutex_lock(&pools_lock
);
83 list_for_each_entry(pool
, &dev
->dma_pools
, pools
) {
87 spin_lock_irq(&pool
->lock
);
88 list_for_each_entry(page
, &pool
->page_list
, page_list
) {
90 blocks
+= page
->in_use
;
92 spin_unlock_irq(&pool
->lock
);
94 /* per-pool info, no real statistics yet */
95 temp
= scnprintf(next
, size
, "%-16s %4u %4Zu %4Zu %2u\n",
97 pages
* (pool
->allocation
/ pool
->size
),
102 mutex_unlock(&pools_lock
);
104 return PAGE_SIZE
- size
;
107 static DEVICE_ATTR(pools
, S_IRUGO
, show_pools
, NULL
);
110 * dma_pool_create - Creates a pool of consistent memory blocks, for dma.
111 * @name: name of pool, for diagnostics
112 * @dev: device that will be doing the DMA
113 * @size: size of the blocks in this pool.
114 * @align: alignment requirement for blocks; must be a power of two
115 * @boundary: returned blocks won't cross this power of two boundary
116 * Context: !in_interrupt()
118 * Returns a dma allocation pool with the requested characteristics, or
119 * null if one can't be created. Given one of these pools, dma_pool_alloc()
120 * may be used to allocate memory. Such memory will all have "consistent"
121 * DMA mappings, accessible by the device and its driver without using
122 * cache flushing primitives. The actual size of blocks allocated may be
123 * larger than requested because of alignment.
125 * If @boundary is nonzero, objects returned from dma_pool_alloc() won't
126 * cross that size boundary. This is useful for devices which have
127 * addressing restrictions on individual DMA transfers, such as not crossing
128 * boundaries of 4KBytes.
130 struct dma_pool
*dma_pool_create(const char *name
, struct device
*dev
,
131 size_t size
, size_t align
, size_t boundary
)
133 struct dma_pool
*retval
;
138 } else if (align
& (align
- 1)) {
144 } else if (size
< 4) {
148 if ((size
% align
) != 0)
149 size
= ALIGN(size
, align
);
151 allocation
= max_t(size_t, size
, PAGE_SIZE
);
154 boundary
= allocation
;
155 } else if ((boundary
< size
) || (boundary
& (boundary
- 1))) {
159 retval
= kmalloc_node(sizeof(*retval
), GFP_KERNEL
, dev_to_node(dev
));
163 strlcpy(retval
->name
, name
, sizeof(retval
->name
));
167 INIT_LIST_HEAD(&retval
->page_list
);
168 spin_lock_init(&retval
->lock
);
170 retval
->boundary
= boundary
;
171 retval
->allocation
= allocation
;
176 mutex_lock(&pools_lock
);
177 if (list_empty(&dev
->dma_pools
))
178 ret
= device_create_file(dev
, &dev_attr_pools
);
181 /* note: not currently insisting "name" be unique */
183 list_add(&retval
->pools
, &dev
->dma_pools
);
188 mutex_unlock(&pools_lock
);
190 INIT_LIST_HEAD(&retval
->pools
);
194 EXPORT_SYMBOL(dma_pool_create
);
196 static void pool_initialise_page(struct dma_pool
*pool
, struct dma_page
*page
)
198 unsigned int offset
= 0;
199 unsigned int next_boundary
= pool
->boundary
;
202 unsigned int next
= offset
+ pool
->size
;
203 if (unlikely((next
+ pool
->size
) >= next_boundary
)) {
204 next
= next_boundary
;
205 next_boundary
+= pool
->boundary
;
207 *(int *)(page
->vaddr
+ offset
) = next
;
209 } while (offset
< pool
->allocation
);
212 static struct dma_page
*pool_alloc_page(struct dma_pool
*pool
, gfp_t mem_flags
)
214 struct dma_page
*page
;
216 page
= kmalloc(sizeof(*page
), mem_flags
);
219 page
->vaddr
= dma_alloc_coherent(pool
->dev
, pool
->allocation
,
220 &page
->dma
, mem_flags
);
223 memset(page
->vaddr
, POOL_POISON_FREED
, pool
->allocation
);
225 pool_initialise_page(pool
, page
);
235 static inline int is_page_busy(struct dma_page
*page
)
237 return page
->in_use
!= 0;
240 static void pool_free_page(struct dma_pool
*pool
, struct dma_page
*page
)
242 dma_addr_t dma
= page
->dma
;
245 memset(page
->vaddr
, POOL_POISON_FREED
, pool
->allocation
);
247 dma_free_coherent(pool
->dev
, pool
->allocation
, page
->vaddr
, dma
);
248 list_del(&page
->page_list
);
253 * dma_pool_destroy - destroys a pool of dma memory blocks.
254 * @pool: dma pool that will be destroyed
255 * Context: !in_interrupt()
257 * Caller guarantees that no more memory from the pool is in use,
258 * and that nothing will try to use the pool after this call.
260 void dma_pool_destroy(struct dma_pool
*pool
)
262 mutex_lock(&pools_lock
);
263 list_del(&pool
->pools
);
264 if (pool
->dev
&& list_empty(&pool
->dev
->dma_pools
))
265 device_remove_file(pool
->dev
, &dev_attr_pools
);
266 mutex_unlock(&pools_lock
);
268 while (!list_empty(&pool
->page_list
)) {
269 struct dma_page
*page
;
270 page
= list_entry(pool
->page_list
.next
,
271 struct dma_page
, page_list
);
272 if (is_page_busy(page
)) {
275 "dma_pool_destroy %s, %p busy\n",
276 pool
->name
, page
->vaddr
);
279 "dma_pool_destroy %s, %p busy\n",
280 pool
->name
, page
->vaddr
);
281 /* leak the still-in-use consistent memory */
282 list_del(&page
->page_list
);
285 pool_free_page(pool
, page
);
290 EXPORT_SYMBOL(dma_pool_destroy
);
293 * dma_pool_alloc - get a block of consistent memory
294 * @pool: dma pool that will produce the block
295 * @mem_flags: GFP_* bitmask
296 * @handle: pointer to dma address of block
298 * This returns the kernel virtual address of a currently unused block,
299 * and reports its dma address through the handle.
300 * If such a memory block can't be allocated, %NULL is returned.
302 void *dma_pool_alloc(struct dma_pool
*pool
, gfp_t mem_flags
,
306 struct dma_page
*page
;
310 might_sleep_if(mem_flags
& __GFP_WAIT
);
312 spin_lock_irqsave(&pool
->lock
, flags
);
313 list_for_each_entry(page
, &pool
->page_list
, page_list
) {
314 if (page
->offset
< pool
->allocation
)
318 /* pool_alloc_page() might sleep, so temporarily drop &pool->lock */
319 spin_unlock_irqrestore(&pool
->lock
, flags
);
321 page
= pool_alloc_page(pool
, mem_flags
);
325 spin_lock_irqsave(&pool
->lock
, flags
);
327 list_add(&page
->page_list
, &pool
->page_list
);
330 offset
= page
->offset
;
331 page
->offset
= *(int *)(page
->vaddr
+ offset
);
332 retval
= offset
+ page
->vaddr
;
333 *handle
= offset
+ page
->dma
;
338 /* page->offset is stored in first 4 bytes */
339 for (i
= sizeof(page
->offset
); i
< pool
->size
; i
++) {
340 if (data
[i
] == POOL_POISON_FREED
)
344 "dma_pool_alloc %s, %p (corruped)\n",
347 pr_err("dma_pool_alloc %s, %p (corruped)\n",
351 * Dump the first 4 bytes even if they are not
354 print_hex_dump(KERN_ERR
, "", DUMP_PREFIX_OFFSET
, 16, 1,
355 data
, pool
->size
, 1);
359 memset(retval
, POOL_POISON_ALLOCATED
, pool
->size
);
361 spin_unlock_irqrestore(&pool
->lock
, flags
);
364 EXPORT_SYMBOL(dma_pool_alloc
);
366 static struct dma_page
*pool_find_page(struct dma_pool
*pool
, dma_addr_t dma
)
368 struct dma_page
*page
;
370 list_for_each_entry(page
, &pool
->page_list
, page_list
) {
373 if (dma
< (page
->dma
+ pool
->allocation
))
380 * dma_pool_free - put block back into dma pool
381 * @pool: the dma pool holding the block
382 * @vaddr: virtual address of block
383 * @dma: dma address of block
385 * Caller promises neither device nor driver will again touch this block
386 * unless it is first re-allocated.
388 void dma_pool_free(struct dma_pool
*pool
, void *vaddr
, dma_addr_t dma
)
390 struct dma_page
*page
;
394 spin_lock_irqsave(&pool
->lock
, flags
);
395 page
= pool_find_page(pool
, dma
);
397 spin_unlock_irqrestore(&pool
->lock
, flags
);
400 "dma_pool_free %s, %p/%lx (bad dma)\n",
401 pool
->name
, vaddr
, (unsigned long)dma
);
403 printk(KERN_ERR
"dma_pool_free %s, %p/%lx (bad dma)\n",
404 pool
->name
, vaddr
, (unsigned long)dma
);
408 offset
= vaddr
- page
->vaddr
;
410 if ((dma
- page
->dma
) != offset
) {
411 spin_unlock_irqrestore(&pool
->lock
, flags
);
414 "dma_pool_free %s, %p (bad vaddr)/%Lx\n",
415 pool
->name
, vaddr
, (unsigned long long)dma
);
418 "dma_pool_free %s, %p (bad vaddr)/%Lx\n",
419 pool
->name
, vaddr
, (unsigned long long)dma
);
423 unsigned int chain
= page
->offset
;
424 while (chain
< pool
->allocation
) {
425 if (chain
!= offset
) {
426 chain
= *(int *)(page
->vaddr
+ chain
);
429 spin_unlock_irqrestore(&pool
->lock
, flags
);
431 dev_err(pool
->dev
, "dma_pool_free %s, dma %Lx "
432 "already free\n", pool
->name
,
433 (unsigned long long)dma
);
435 printk(KERN_ERR
"dma_pool_free %s, dma %Lx "
436 "already free\n", pool
->name
,
437 (unsigned long long)dma
);
441 memset(vaddr
, POOL_POISON_FREED
, pool
->size
);
445 *(int *)vaddr
= page
->offset
;
446 page
->offset
= offset
;
448 * Resist a temptation to do
449 * if (!is_page_busy(page)) pool_free_page(pool, page);
450 * Better have a few empty pages hang around.
452 spin_unlock_irqrestore(&pool
->lock
, flags
);
454 EXPORT_SYMBOL(dma_pool_free
);
459 static void dmam_pool_release(struct device
*dev
, void *res
)
461 struct dma_pool
*pool
= *(struct dma_pool
**)res
;
463 dma_pool_destroy(pool
);
466 static int dmam_pool_match(struct device
*dev
, void *res
, void *match_data
)
468 return *(struct dma_pool
**)res
== match_data
;
472 * dmam_pool_create - Managed dma_pool_create()
473 * @name: name of pool, for diagnostics
474 * @dev: device that will be doing the DMA
475 * @size: size of the blocks in this pool.
476 * @align: alignment requirement for blocks; must be a power of two
477 * @allocation: returned blocks won't cross this boundary (or zero)
479 * Managed dma_pool_create(). DMA pool created with this function is
480 * automatically destroyed on driver detach.
482 struct dma_pool
*dmam_pool_create(const char *name
, struct device
*dev
,
483 size_t size
, size_t align
, size_t allocation
)
485 struct dma_pool
**ptr
, *pool
;
487 ptr
= devres_alloc(dmam_pool_release
, sizeof(*ptr
), GFP_KERNEL
);
491 pool
= *ptr
= dma_pool_create(name
, dev
, size
, align
, allocation
);
493 devres_add(dev
, ptr
);
499 EXPORT_SYMBOL(dmam_pool_create
);
502 * dmam_pool_destroy - Managed dma_pool_destroy()
503 * @pool: dma pool that will be destroyed
505 * Managed dma_pool_destroy().
507 void dmam_pool_destroy(struct dma_pool
*pool
)
509 struct device
*dev
= pool
->dev
;
511 WARN_ON(devres_destroy(dev
, dmam_pool_release
, dmam_pool_match
, pool
));
512 dma_pool_destroy(pool
);
514 EXPORT_SYMBOL(dmam_pool_destroy
);
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