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 spin_lock_irq(&pool->lock);
90 list_for_each_entry(page, &pool->page_list, page_list) {
92 blocks += page->in_use;
94 spin_unlock_irq(&pool->lock);
96 /* per-pool info, no real statistics yet */
97 temp = scnprintf(next, size, "%-16s %4u %4Zu %4Zu %2u\n",
99 pages * (pool->allocation / pool->size),
104 mutex_unlock(&pools_lock);
106 return PAGE_SIZE - size;
109 static DEVICE_ATTR(pools, S_IRUGO, show_pools, NULL);
112 * dma_pool_create - Creates a pool of consistent memory blocks, for dma.
113 * @name: name of pool, for diagnostics
114 * @dev: device that will be doing the DMA
115 * @size: size of the blocks in this pool.
116 * @align: alignment requirement for blocks; must be a power of two
117 * @boundary: returned blocks won't cross this power of two boundary
118 * Context: !in_interrupt()
120 * Returns a dma allocation pool with the requested characteristics, or
121 * null if one can't be created. Given one of these pools, dma_pool_alloc()
122 * may be used to allocate memory. Such memory will all have "consistent"
123 * DMA mappings, accessible by the device and its driver without using
124 * cache flushing primitives. The actual size of blocks allocated may be
125 * larger than requested because of alignment.
127 * If @boundary is nonzero, objects returned from dma_pool_alloc() won't
128 * cross that size boundary. This is useful for devices which have
129 * addressing restrictions on individual DMA transfers, such as not crossing
130 * boundaries of 4KBytes.
132 struct dma_pool *dma_pool_create(const char *name, struct device *dev,
133 size_t size, size_t align, size_t boundary)
135 struct dma_pool *retval;
140 } else if (align & (align - 1)) {
146 } else if (size < 4) {
150 if ((size % align) != 0)
151 size = ALIGN(size, align);
153 allocation = max_t(size_t, size, PAGE_SIZE);
156 boundary = allocation;
157 } else if ((boundary < size) || (boundary & (boundary - 1))) {
161 retval = kmalloc_node(sizeof(*retval), GFP_KERNEL, dev_to_node(dev));
165 strlcpy(retval->name, name, sizeof(retval->name));
169 INIT_LIST_HEAD(&retval->page_list);
170 spin_lock_init(&retval->lock);
172 retval->boundary = boundary;
173 retval->allocation = allocation;
174 init_waitqueue_head(&retval->waitq);
179 mutex_lock(&pools_lock);
180 if (list_empty(&dev->dma_pools))
181 ret = device_create_file(dev, &dev_attr_pools);
184 /* note: not currently insisting "name" be unique */
186 list_add(&retval->pools, &dev->dma_pools);
191 mutex_unlock(&pools_lock);
193 INIT_LIST_HEAD(&retval->pools);
197 EXPORT_SYMBOL(dma_pool_create);
199 static void pool_initialise_page(struct dma_pool *pool, struct dma_page *page)
201 unsigned int offset = 0;
202 unsigned int next_boundary = pool->boundary;
205 unsigned int next = offset + pool->size;
206 if (unlikely((next + pool->size) >= next_boundary)) {
207 next = next_boundary;
208 next_boundary += pool->boundary;
210 *(int *)(page->vaddr + offset) = next;
212 } while (offset < pool->allocation);
215 #ifdef CONFIG_FSL_UTP
216 static struct dma_page *pool_alloc_page_nonbufferable(struct dma_pool *pool, gfp_t mem_flags)
218 struct dma_page *page;
220 page = kmalloc(sizeof(*page), mem_flags);
223 page->vaddr = dma_alloc_noncacheable(pool->dev, pool->allocation,
224 &page->dma, mem_flags);
227 memset(page->vaddr, POOL_POISON_FREED, pool->allocation);
229 pool_initialise_page(pool, page);
230 list_add(&page->page_list, &pool->page_list);
241 static struct dma_page *pool_alloc_page(struct dma_pool *pool, gfp_t mem_flags)
243 struct dma_page *page;
245 page = kmalloc(sizeof(*page), mem_flags);
248 page->vaddr = dma_alloc_coherent(pool->dev, pool->allocation,
249 &page->dma, mem_flags);
252 memset(page->vaddr, POOL_POISON_FREED, pool->allocation);
254 pool_initialise_page(pool, page);
255 list_add(&page->page_list, &pool->page_list);
265 static inline int is_page_busy(struct dma_page *page)
267 return page->in_use != 0;
270 static void pool_free_page(struct dma_pool *pool, struct dma_page *page)
272 dma_addr_t dma = page->dma;
275 memset(page->vaddr, POOL_POISON_FREED, pool->allocation);
277 dma_free_coherent(pool->dev, pool->allocation, page->vaddr, dma);
278 list_del(&page->page_list);
283 * dma_pool_destroy - destroys a pool of dma memory blocks.
284 * @pool: dma pool that will be destroyed
285 * Context: !in_interrupt()
287 * Caller guarantees that no more memory from the pool is in use,
288 * and that nothing will try to use the pool after this call.
290 void dma_pool_destroy(struct dma_pool *pool)
292 mutex_lock(&pools_lock);
293 list_del(&pool->pools);
294 if (pool->dev && list_empty(&pool->dev->dma_pools))
295 device_remove_file(pool->dev, &dev_attr_pools);
296 mutex_unlock(&pools_lock);
298 while (!list_empty(&pool->page_list)) {
299 struct dma_page *page;
300 page = list_entry(pool->page_list.next,
301 struct dma_page, page_list);
302 if (is_page_busy(page)) {
305 "dma_pool_destroy %s, %p busy\n",
306 pool->name, page->vaddr);
309 "dma_pool_destroy %s, %p busy\n",
310 pool->name, page->vaddr);
311 /* leak the still-in-use consistent memory */
312 list_del(&page->page_list);
315 pool_free_page(pool, page);
320 EXPORT_SYMBOL(dma_pool_destroy);
323 * dma_pool_alloc - get a block of consistent memory
324 * @pool: dma pool that will produce the block
325 * @mem_flags: GFP_* bitmask
326 * @handle: pointer to dma address of block
328 * This returns the kernel virtual address of a currently unused block,
329 * and reports its dma address through the handle.
330 * If such a memory block can't be allocated, %NULL is returned.
332 void *dma_pool_alloc(struct dma_pool *pool, gfp_t mem_flags,
336 struct dma_page *page;
340 might_sleep_if(mem_flags & __GFP_WAIT);
342 spin_lock_irqsave(&pool->lock, flags);
344 list_for_each_entry(page, &pool->page_list, page_list) {
345 if (page->offset < pool->allocation)
348 page = pool_alloc_page(pool, GFP_ATOMIC);
350 if (mem_flags & __GFP_WAIT) {
351 DECLARE_WAITQUEUE(wait, current);
353 __set_current_state(TASK_UNINTERRUPTIBLE);
354 __add_wait_queue(&pool->waitq, &wait);
355 spin_unlock_irqrestore(&pool->lock, flags);
357 schedule_timeout(POOL_TIMEOUT_JIFFIES);
359 spin_lock_irqsave(&pool->lock, flags);
360 __remove_wait_queue(&pool->waitq, &wait);
369 offset = page->offset;
370 page->offset = *(int *)(page->vaddr + offset);
371 retval = offset + page->vaddr;
372 *handle = offset + page->dma;
374 memset(retval, POOL_POISON_ALLOCATED, pool->size);
377 spin_unlock_irqrestore(&pool->lock, flags);
380 EXPORT_SYMBOL(dma_pool_alloc);
382 #ifdef CONFIG_FSL_UTP
384 * dma_pool_alloc_nonbufferable - get a block of consistent memory
385 * @pool: dma pool that will produce the block
386 * @mem_flags: GFP_* bitmask
387 * @handle: pointer to dma address of block
389 * This returns the kernel virtual address of a currently unused block,
390 * and reports its dma address through the handle.
391 * If such a memory block can't be allocated, %NULL is returned.
393 void *dma_pool_alloc_nonbufferable(struct dma_pool *pool, gfp_t mem_flags,
397 struct dma_page *page;
401 might_sleep_if(mem_flags & __GFP_WAIT);
403 spin_lock_irqsave(&pool->lock, flags);
405 list_for_each_entry(page, &pool->page_list, page_list) {
406 if (page->offset < pool->allocation)
409 page = pool_alloc_page_nonbufferable(pool, GFP_ATOMIC);
411 if (mem_flags & __GFP_WAIT) {
412 DECLARE_WAITQUEUE(wait, current);
414 __set_current_state(TASK_UNINTERRUPTIBLE);
415 __add_wait_queue(&pool->waitq, &wait);
416 spin_unlock_irqrestore(&pool->lock, flags);
418 schedule_timeout(POOL_TIMEOUT_JIFFIES);
420 spin_lock_irqsave(&pool->lock, flags);
421 __remove_wait_queue(&pool->waitq, &wait);
430 offset = page->offset;
431 page->offset = *(int *)(page->vaddr + offset);
432 retval = offset + page->vaddr;
433 *handle = offset + page->dma;
435 memset(retval, POOL_POISON_ALLOCATED, pool->size);
438 spin_unlock_irqrestore(&pool->lock, flags);
441 EXPORT_SYMBOL(dma_pool_alloc_nonbufferable);
444 static struct dma_page *pool_find_page(struct dma_pool *pool, dma_addr_t dma)
446 struct dma_page *page;
448 list_for_each_entry(page, &pool->page_list, page_list) {
451 if (dma < (page->dma + pool->allocation))
458 * dma_pool_free - put block back into dma pool
459 * @pool: the dma pool holding the block
460 * @vaddr: virtual address of block
461 * @dma: dma address of block
463 * Caller promises neither device nor driver will again touch this block
464 * unless it is first re-allocated.
466 void dma_pool_free(struct dma_pool *pool, void *vaddr, dma_addr_t dma)
468 struct dma_page *page;
472 spin_lock_irqsave(&pool->lock, flags);
473 page = pool_find_page(pool, dma);
475 spin_unlock_irqrestore(&pool->lock, flags);
478 "dma_pool_free %s, %p/%lx (bad dma)\n",
479 pool->name, vaddr, (unsigned long)dma);
481 printk(KERN_ERR "dma_pool_free %s, %p/%lx (bad dma)\n",
482 pool->name, vaddr, (unsigned long)dma);
486 offset = vaddr - page->vaddr;
488 if ((dma - page->dma) != offset) {
489 spin_unlock_irqrestore(&pool->lock, flags);
492 "dma_pool_free %s, %p (bad vaddr)/%Lx\n",
493 pool->name, vaddr, (unsigned long long)dma);
496 "dma_pool_free %s, %p (bad vaddr)/%Lx\n",
497 pool->name, vaddr, (unsigned long long)dma);
501 unsigned int chain = page->offset;
502 while (chain < pool->allocation) {
503 if (chain != offset) {
504 chain = *(int *)(page->vaddr + chain);
507 spin_unlock_irqrestore(&pool->lock, flags);
509 dev_err(pool->dev, "dma_pool_free %s, dma %Lx "
510 "already free\n", pool->name,
511 (unsigned long long)dma);
513 printk(KERN_ERR "dma_pool_free %s, dma %Lx "
514 "already free\n", pool->name,
515 (unsigned long long)dma);
519 memset(vaddr, POOL_POISON_FREED, pool->size);
523 *(int *)vaddr = page->offset;
524 page->offset = offset;
525 if (waitqueue_active(&pool->waitq))
526 wake_up_locked(&pool->waitq);
528 * Resist a temptation to do
529 * if (!is_page_busy(page)) pool_free_page(pool, page);
530 * Better have a few empty pages hang around.
532 spin_unlock_irqrestore(&pool->lock, flags);
534 EXPORT_SYMBOL(dma_pool_free);
539 static void dmam_pool_release(struct device *dev, void *res)
541 struct dma_pool *pool = *(struct dma_pool **)res;
543 dma_pool_destroy(pool);
546 static int dmam_pool_match(struct device *dev, void *res, void *match_data)
548 return *(struct dma_pool **)res == match_data;
552 * dmam_pool_create - Managed dma_pool_create()
553 * @name: name of pool, for diagnostics
554 * @dev: device that will be doing the DMA
555 * @size: size of the blocks in this pool.
556 * @align: alignment requirement for blocks; must be a power of two
557 * @allocation: returned blocks won't cross this boundary (or zero)
559 * Managed dma_pool_create(). DMA pool created with this function is
560 * automatically destroyed on driver detach.
562 struct dma_pool *dmam_pool_create(const char *name, struct device *dev,
563 size_t size, size_t align, size_t allocation)
565 struct dma_pool **ptr, *pool;
567 ptr = devres_alloc(dmam_pool_release, sizeof(*ptr), GFP_KERNEL);
571 pool = *ptr = dma_pool_create(name, dev, size, align, allocation);
573 devres_add(dev, ptr);
579 EXPORT_SYMBOL(dmam_pool_create);
582 * dmam_pool_destroy - Managed dma_pool_destroy()
583 * @pool: dma pool that will be destroyed
585 * Managed dma_pool_destroy().
587 void dmam_pool_destroy(struct dma_pool *pool)
589 struct device *dev = pool->dev;
591 dma_pool_destroy(pool);
592 WARN_ON(devres_destroy(dev, dmam_pool_release, dmam_pool_match, pool));
594 EXPORT_SYMBOL(dmam_pool_destroy);