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/module.h>
31 #include <linux/mutex.h>
32 #include <linux/poison.h>
33 #include <linux/sched.h>
34 #include <linux/slab.h>
35 #include <linux/spinlock.h>
36 #include <linux/string.h>
37 #include <linux/types.h>
38 #include <linux/wait.h>
40 #if defined(CONFIG_DEBUG_SLAB) || defined(CONFIG_SLUB_DEBUG_ON)
41 #define DMAPOOL_DEBUG 1
44 struct dma_pool
{ /* the pool */
45 struct list_head page_list
;
52 wait_queue_head_t waitq
;
53 struct list_head pools
;
56 struct dma_page
{ /* cacheable header for 'allocation' bytes */
57 struct list_head page_list
;
64 #define POOL_TIMEOUT_JIFFIES ((100 /* msec */ * HZ) / 1000)
66 static DEFINE_MUTEX(pools_lock
);
69 show_pools(struct device
*dev
, struct device_attribute
*attr
, char *buf
)
74 struct dma_page
*page
;
75 struct dma_pool
*pool
;
80 temp
= scnprintf(next
, size
, "poolinfo - 0.1\n");
84 mutex_lock(&pools_lock
);
85 list_for_each_entry(pool
, &dev
->dma_pools
, pools
) {
89 list_for_each_entry(page
, &pool
->page_list
, page_list
) {
91 blocks
+= page
->in_use
;
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
;
172 init_waitqueue_head(&retval
->waitq
);
177 mutex_lock(&pools_lock
);
178 if (list_empty(&dev
->dma_pools
))
179 ret
= device_create_file(dev
, &dev_attr_pools
);
182 /* note: not currently insisting "name" be unique */
184 list_add(&retval
->pools
, &dev
->dma_pools
);
189 mutex_unlock(&pools_lock
);
191 INIT_LIST_HEAD(&retval
->pools
);
195 EXPORT_SYMBOL(dma_pool_create
);
197 static void pool_initialise_page(struct dma_pool
*pool
, struct dma_page
*page
)
199 unsigned int offset
= 0;
200 unsigned int next_boundary
= pool
->boundary
;
203 unsigned int next
= offset
+ pool
->size
;
204 if (unlikely((next
+ pool
->size
) >= next_boundary
)) {
205 next
= next_boundary
;
206 next_boundary
+= pool
->boundary
;
208 *(int *)(page
->vaddr
+ offset
) = next
;
210 } while (offset
< pool
->allocation
);
213 static struct dma_page
*pool_alloc_page(struct dma_pool
*pool
, gfp_t mem_flags
)
215 struct dma_page
*page
;
217 page
= kmalloc(sizeof(*page
), mem_flags
);
220 page
->vaddr
= dma_alloc_coherent(pool
->dev
, pool
->allocation
,
221 &page
->dma
, mem_flags
);
224 memset(page
->vaddr
, POOL_POISON_FREED
, pool
->allocation
);
226 pool_initialise_page(pool
, page
);
227 list_add(&page
->page_list
, &pool
->page_list
);
237 static inline int is_page_busy(struct dma_page
*page
)
239 return page
->in_use
!= 0;
242 static void pool_free_page(struct dma_pool
*pool
, struct dma_page
*page
)
244 dma_addr_t dma
= page
->dma
;
247 memset(page
->vaddr
, POOL_POISON_FREED
, pool
->allocation
);
249 dma_free_coherent(pool
->dev
, pool
->allocation
, page
->vaddr
, dma
);
250 list_del(&page
->page_list
);
255 * dma_pool_destroy - destroys a pool of dma memory blocks.
256 * @pool: dma pool that will be destroyed
257 * Context: !in_interrupt()
259 * Caller guarantees that no more memory from the pool is in use,
260 * and that nothing will try to use the pool after this call.
262 void dma_pool_destroy(struct dma_pool
*pool
)
264 mutex_lock(&pools_lock
);
265 list_del(&pool
->pools
);
266 if (pool
->dev
&& list_empty(&pool
->dev
->dma_pools
))
267 device_remove_file(pool
->dev
, &dev_attr_pools
);
268 mutex_unlock(&pools_lock
);
270 while (!list_empty(&pool
->page_list
)) {
271 struct dma_page
*page
;
272 page
= list_entry(pool
->page_list
.next
,
273 struct dma_page
, page_list
);
274 if (is_page_busy(page
)) {
277 "dma_pool_destroy %s, %p busy\n",
278 pool
->name
, page
->vaddr
);
281 "dma_pool_destroy %s, %p busy\n",
282 pool
->name
, page
->vaddr
);
283 /* leak the still-in-use consistent memory */
284 list_del(&page
->page_list
);
287 pool_free_page(pool
, page
);
292 EXPORT_SYMBOL(dma_pool_destroy
);
295 * dma_pool_alloc - get a block of consistent memory
296 * @pool: dma pool that will produce the block
297 * @mem_flags: GFP_* bitmask
298 * @handle: pointer to dma address of block
300 * This returns the kernel virtual address of a currently unused block,
301 * and reports its dma address through the handle.
302 * If such a memory block can't be allocated, %NULL is returned.
304 void *dma_pool_alloc(struct dma_pool
*pool
, gfp_t mem_flags
,
308 struct dma_page
*page
;
312 spin_lock_irqsave(&pool
->lock
, flags
);
314 list_for_each_entry(page
, &pool
->page_list
, page_list
) {
315 if (page
->offset
< pool
->allocation
)
318 page
= pool_alloc_page(pool
, GFP_ATOMIC
);
320 if (mem_flags
& __GFP_WAIT
) {
321 DECLARE_WAITQUEUE(wait
, current
);
323 __set_current_state(TASK_INTERRUPTIBLE
);
324 __add_wait_queue(&pool
->waitq
, &wait
);
325 spin_unlock_irqrestore(&pool
->lock
, flags
);
327 schedule_timeout(POOL_TIMEOUT_JIFFIES
);
329 spin_lock_irqsave(&pool
->lock
, flags
);
330 __remove_wait_queue(&pool
->waitq
, &wait
);
339 offset
= page
->offset
;
340 page
->offset
= *(int *)(page
->vaddr
+ offset
);
341 retval
= offset
+ page
->vaddr
;
342 *handle
= offset
+ page
->dma
;
344 memset(retval
, POOL_POISON_ALLOCATED
, pool
->size
);
347 spin_unlock_irqrestore(&pool
->lock
, flags
);
350 EXPORT_SYMBOL(dma_pool_alloc
);
352 static struct dma_page
*pool_find_page(struct dma_pool
*pool
, dma_addr_t dma
)
355 struct dma_page
*page
;
357 spin_lock_irqsave(&pool
->lock
, flags
);
358 list_for_each_entry(page
, &pool
->page_list
, page_list
) {
361 if (dma
< (page
->dma
+ pool
->allocation
))
366 spin_unlock_irqrestore(&pool
->lock
, flags
);
371 * dma_pool_free - put block back into dma pool
372 * @pool: the dma pool holding the block
373 * @vaddr: virtual address of block
374 * @dma: dma address of block
376 * Caller promises neither device nor driver will again touch this block
377 * unless it is first re-allocated.
379 void dma_pool_free(struct dma_pool
*pool
, void *vaddr
, dma_addr_t dma
)
381 struct dma_page
*page
;
385 page
= pool_find_page(pool
, dma
);
389 "dma_pool_free %s, %p/%lx (bad dma)\n",
390 pool
->name
, vaddr
, (unsigned long)dma
);
392 printk(KERN_ERR
"dma_pool_free %s, %p/%lx (bad dma)\n",
393 pool
->name
, vaddr
, (unsigned long)dma
);
397 offset
= vaddr
- page
->vaddr
;
399 if ((dma
- page
->dma
) != offset
) {
402 "dma_pool_free %s, %p (bad vaddr)/%Lx\n",
403 pool
->name
, vaddr
, (unsigned long long)dma
);
406 "dma_pool_free %s, %p (bad vaddr)/%Lx\n",
407 pool
->name
, vaddr
, (unsigned long long)dma
);
411 unsigned int chain
= page
->offset
;
412 while (chain
< pool
->allocation
) {
413 if (chain
!= offset
) {
414 chain
= *(int *)(page
->vaddr
+ chain
);
418 dev_err(pool
->dev
, "dma_pool_free %s, dma %Lx "
419 "already free\n", pool
->name
,
420 (unsigned long long)dma
);
422 printk(KERN_ERR
"dma_pool_free %s, dma %Lx "
423 "already free\n", pool
->name
,
424 (unsigned long long)dma
);
428 memset(vaddr
, POOL_POISON_FREED
, pool
->size
);
431 spin_lock_irqsave(&pool
->lock
, flags
);
433 *(int *)vaddr
= page
->offset
;
434 page
->offset
= offset
;
435 if (waitqueue_active(&pool
->waitq
))
436 wake_up_locked(&pool
->waitq
);
438 * Resist a temptation to do
439 * if (!is_page_busy(page)) pool_free_page(pool, page);
440 * Better have a few empty pages hang around.
442 spin_unlock_irqrestore(&pool
->lock
, flags
);
444 EXPORT_SYMBOL(dma_pool_free
);
449 static void dmam_pool_release(struct device
*dev
, void *res
)
451 struct dma_pool
*pool
= *(struct dma_pool
**)res
;
453 dma_pool_destroy(pool
);
456 static int dmam_pool_match(struct device
*dev
, void *res
, void *match_data
)
458 return *(struct dma_pool
**)res
== match_data
;
462 * dmam_pool_create - Managed dma_pool_create()
463 * @name: name of pool, for diagnostics
464 * @dev: device that will be doing the DMA
465 * @size: size of the blocks in this pool.
466 * @align: alignment requirement for blocks; must be a power of two
467 * @allocation: returned blocks won't cross this boundary (or zero)
469 * Managed dma_pool_create(). DMA pool created with this function is
470 * automatically destroyed on driver detach.
472 struct dma_pool
*dmam_pool_create(const char *name
, struct device
*dev
,
473 size_t size
, size_t align
, size_t allocation
)
475 struct dma_pool
**ptr
, *pool
;
477 ptr
= devres_alloc(dmam_pool_release
, sizeof(*ptr
), GFP_KERNEL
);
481 pool
= *ptr
= dma_pool_create(name
, dev
, size
, align
, allocation
);
483 devres_add(dev
, ptr
);
489 EXPORT_SYMBOL(dmam_pool_create
);
492 * dmam_pool_destroy - Managed dma_pool_destroy()
493 * @pool: dma pool that will be destroyed
495 * Managed dma_pool_destroy().
497 void dmam_pool_destroy(struct dma_pool
*pool
)
499 struct device
*dev
= pool
->dev
;
501 dma_pool_destroy(pool
);
502 WARN_ON(devres_destroy(dev
, dmam_pool_release
, dmam_pool_match
, pool
));
504 EXPORT_SYMBOL(dmam_pool_destroy
);
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