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 wait_queue_head_t waitq;
54 struct list_head pools;
57 struct dma_page { /* cacheable header for 'allocation' bytes */
58 struct list_head page_list;
65 static DEFINE_MUTEX(pools_lock);
68 show_pools(struct device *dev, struct device_attribute *attr, char *buf)
73 struct dma_page *page;
74 struct dma_pool *pool;
79 temp = scnprintf(next, size, "poolinfo - 0.1\n");
83 mutex_lock(&pools_lock);
84 list_for_each_entry(pool, &dev->dma_pools, pools) {
88 spin_lock_irq(&pool->lock);
89 list_for_each_entry(page, &pool->page_list, page_list) {
91 blocks += page->in_use;
93 spin_unlock_irq(&pool->lock);
95 /* per-pool info, no real statistics yet */
96 temp = scnprintf(next, size, "%-16s %4u %4Zu %4Zu %2u\n",
98 pages * (pool->allocation / pool->size),
103 mutex_unlock(&pools_lock);
105 return PAGE_SIZE - size;
108 static DEVICE_ATTR(pools, S_IRUGO, show_pools, NULL);
111 * dma_pool_create - Creates a pool of consistent memory blocks, for dma.
112 * @name: name of pool, for diagnostics
113 * @dev: device that will be doing the DMA
114 * @size: size of the blocks in this pool.
115 * @align: alignment requirement for blocks; must be a power of two
116 * @boundary: returned blocks won't cross this power of two boundary
117 * Context: !in_interrupt()
119 * Returns a dma allocation pool with the requested characteristics, or
120 * null if one can't be created. Given one of these pools, dma_pool_alloc()
121 * may be used to allocate memory. Such memory will all have "consistent"
122 * DMA mappings, accessible by the device and its driver without using
123 * cache flushing primitives. The actual size of blocks allocated may be
124 * larger than requested because of alignment.
126 * If @boundary is nonzero, objects returned from dma_pool_alloc() won't
127 * cross that size boundary. This is useful for devices which have
128 * addressing restrictions on individual DMA transfers, such as not crossing
129 * boundaries of 4KBytes.
131 struct dma_pool *dma_pool_create(const char *name, struct device *dev,
132 size_t size, size_t align, size_t boundary)
134 struct dma_pool *retval;
139 } else if (align & (align - 1)) {
145 } else if (size < 4) {
149 if ((size % align) != 0)
150 size = ALIGN(size, align);
152 allocation = max_t(size_t, size, PAGE_SIZE);
155 boundary = allocation;
156 } else if ((boundary < size) || (boundary & (boundary - 1))) {
160 retval = kmalloc_node(sizeof(*retval), GFP_KERNEL, dev_to_node(dev));
164 strlcpy(retval->name, name, sizeof(retval->name));
168 INIT_LIST_HEAD(&retval->page_list);
169 spin_lock_init(&retval->lock);
171 retval->boundary = boundary;
172 retval->allocation = allocation;
173 init_waitqueue_head(&retval->waitq);
178 mutex_lock(&pools_lock);
179 if (list_empty(&dev->dma_pools))
180 ret = device_create_file(dev, &dev_attr_pools);
183 /* note: not currently insisting "name" be unique */
185 list_add(&retval->pools, &dev->dma_pools);
190 mutex_unlock(&pools_lock);
192 INIT_LIST_HEAD(&retval->pools);
196 EXPORT_SYMBOL(dma_pool_create);
198 static void pool_initialise_page(struct dma_pool *pool, struct dma_page *page)
200 unsigned int offset = 0;
201 unsigned int next_boundary = pool->boundary;
204 unsigned int next = offset + pool->size;
205 if (unlikely((next + pool->size) >= next_boundary)) {
206 next = next_boundary;
207 next_boundary += pool->boundary;
209 *(int *)(page->vaddr + offset) = next;
211 } while (offset < pool->allocation);
214 static struct dma_page *pool_alloc_page(struct dma_pool *pool, gfp_t mem_flags)
216 struct dma_page *page;
218 page = kmalloc(sizeof(*page), mem_flags);
221 page->vaddr = dma_alloc_coherent(pool->dev, pool->allocation,
222 &page->dma, mem_flags);
225 memset(page->vaddr, POOL_POISON_FREED, pool->allocation);
227 pool_initialise_page(pool, page);
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 might_sleep_if(mem_flags & __GFP_WAIT);
314 spin_lock_irqsave(&pool->lock, flags);
315 list_for_each_entry(page, &pool->page_list, page_list) {
316 if (page->offset < pool->allocation)
320 /* pool_alloc_page() might sleep, so temporarily drop &pool->lock */
321 spin_unlock_irqrestore(&pool->lock, flags);
323 page = pool_alloc_page(pool, mem_flags);
327 spin_lock_irqsave(&pool->lock, flags);
329 list_add(&page->page_list, &pool->page_list);
332 offset = page->offset;
333 page->offset = *(int *)(page->vaddr + offset);
334 retval = offset + page->vaddr;
335 *handle = offset + page->dma;
337 memset(retval, POOL_POISON_ALLOCATED, pool->size);
339 spin_unlock_irqrestore(&pool->lock, flags);
342 EXPORT_SYMBOL(dma_pool_alloc);
344 static struct dma_page *pool_find_page(struct dma_pool *pool, dma_addr_t dma)
346 struct dma_page *page;
348 list_for_each_entry(page, &pool->page_list, page_list) {
351 if (dma < (page->dma + pool->allocation))
358 * dma_pool_free - put block back into dma pool
359 * @pool: the dma pool holding the block
360 * @vaddr: virtual address of block
361 * @dma: dma address of block
363 * Caller promises neither device nor driver will again touch this block
364 * unless it is first re-allocated.
366 void dma_pool_free(struct dma_pool *pool, void *vaddr, dma_addr_t dma)
368 struct dma_page *page;
372 spin_lock_irqsave(&pool->lock, flags);
373 page = pool_find_page(pool, dma);
375 spin_unlock_irqrestore(&pool->lock, flags);
378 "dma_pool_free %s, %p/%lx (bad dma)\n",
379 pool->name, vaddr, (unsigned long)dma);
381 printk(KERN_ERR "dma_pool_free %s, %p/%lx (bad dma)\n",
382 pool->name, vaddr, (unsigned long)dma);
386 offset = vaddr - page->vaddr;
388 if ((dma - page->dma) != offset) {
389 spin_unlock_irqrestore(&pool->lock, flags);
392 "dma_pool_free %s, %p (bad vaddr)/%Lx\n",
393 pool->name, vaddr, (unsigned long long)dma);
396 "dma_pool_free %s, %p (bad vaddr)/%Lx\n",
397 pool->name, vaddr, (unsigned long long)dma);
401 unsigned int chain = page->offset;
402 while (chain < pool->allocation) {
403 if (chain != offset) {
404 chain = *(int *)(page->vaddr + chain);
407 spin_unlock_irqrestore(&pool->lock, flags);
409 dev_err(pool->dev, "dma_pool_free %s, dma %Lx "
410 "already free\n", pool->name,
411 (unsigned long long)dma);
413 printk(KERN_ERR "dma_pool_free %s, dma %Lx "
414 "already free\n", pool->name,
415 (unsigned long long)dma);
419 memset(vaddr, POOL_POISON_FREED, pool->size);
423 *(int *)vaddr = page->offset;
424 page->offset = offset;
425 if (waitqueue_active(&pool->waitq))
426 wake_up_locked(&pool->waitq);
428 * Resist a temptation to do
429 * if (!is_page_busy(page)) pool_free_page(pool, page);
430 * Better have a few empty pages hang around.
432 spin_unlock_irqrestore(&pool->lock, flags);
434 EXPORT_SYMBOL(dma_pool_free);
439 static void dmam_pool_release(struct device *dev, void *res)
441 struct dma_pool *pool = *(struct dma_pool **)res;
443 dma_pool_destroy(pool);
446 static int dmam_pool_match(struct device *dev, void *res, void *match_data)
448 return *(struct dma_pool **)res == match_data;
452 * dmam_pool_create - Managed dma_pool_create()
453 * @name: name of pool, for diagnostics
454 * @dev: device that will be doing the DMA
455 * @size: size of the blocks in this pool.
456 * @align: alignment requirement for blocks; must be a power of two
457 * @allocation: returned blocks won't cross this boundary (or zero)
459 * Managed dma_pool_create(). DMA pool created with this function is
460 * automatically destroyed on driver detach.
462 struct dma_pool *dmam_pool_create(const char *name, struct device *dev,
463 size_t size, size_t align, size_t allocation)
465 struct dma_pool **ptr, *pool;
467 ptr = devres_alloc(dmam_pool_release, sizeof(*ptr), GFP_KERNEL);
471 pool = *ptr = dma_pool_create(name, dev, size, align, allocation);
473 devres_add(dev, ptr);
479 EXPORT_SYMBOL(dmam_pool_create);
482 * dmam_pool_destroy - Managed dma_pool_destroy()
483 * @pool: dma pool that will be destroyed
485 * Managed dma_pool_destroy().
487 void dmam_pool_destroy(struct dma_pool *pool)
489 struct device *dev = pool->dev;
491 WARN_ON(devres_destroy(dev, dmam_pool_release, dmam_pool_match, pool));
492 dma_pool_destroy(pool);
494 EXPORT_SYMBOL(dmam_pool_destroy);