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 struct list_head pools;
55 struct dma_page { /* cacheable header for 'allocation' bytes */
56 struct list_head page_list;
63 static DEFINE_MUTEX(pools_lock);
66 show_pools(struct device *dev, struct device_attribute *attr, char *buf)
71 struct dma_page *page;
72 struct dma_pool *pool;
77 temp = scnprintf(next, size, "poolinfo - 0.1\n");
81 mutex_lock(&pools_lock);
82 list_for_each_entry(pool, &dev->dma_pools, pools) {
86 spin_lock_irq(&pool->lock);
87 list_for_each_entry(page, &pool->page_list, page_list) {
89 blocks += page->in_use;
91 spin_unlock_irq(&pool->lock);
93 /* per-pool info, no real statistics yet */
94 temp = scnprintf(next, size, "%-16s %4u %4Zu %4Zu %2u\n",
96 pages * (pool->allocation / pool->size),
101 mutex_unlock(&pools_lock);
103 return PAGE_SIZE - size;
106 static DEVICE_ATTR(pools, S_IRUGO, show_pools, NULL);
109 * dma_pool_create - Creates a pool of consistent memory blocks, for dma.
110 * @name: name of pool, for diagnostics
111 * @dev: device that will be doing the DMA
112 * @size: size of the blocks in this pool.
113 * @align: alignment requirement for blocks; must be a power of two
114 * @boundary: returned blocks won't cross this power of two boundary
115 * Context: !in_interrupt()
117 * Returns a dma allocation pool with the requested characteristics, or
118 * null if one can't be created. Given one of these pools, dma_pool_alloc()
119 * may be used to allocate memory. Such memory will all have "consistent"
120 * DMA mappings, accessible by the device and its driver without using
121 * cache flushing primitives. The actual size of blocks allocated may be
122 * larger than requested because of alignment.
124 * If @boundary is nonzero, objects returned from dma_pool_alloc() won't
125 * cross that size boundary. This is useful for devices which have
126 * addressing restrictions on individual DMA transfers, such as not crossing
127 * boundaries of 4KBytes.
129 struct dma_pool *dma_pool_create(const char *name, struct device *dev,
130 size_t size, size_t align, size_t boundary)
132 struct dma_pool *retval;
137 } else if (align & (align - 1)) {
143 } else if (size < 4) {
147 if ((size % align) != 0)
148 size = ALIGN(size, align);
150 allocation = max_t(size_t, size, PAGE_SIZE);
153 boundary = allocation;
154 } else if ((boundary < size) || (boundary & (boundary - 1))) {
158 retval = kmalloc_node(sizeof(*retval), GFP_KERNEL, dev_to_node(dev));
162 strlcpy(retval->name, name, sizeof(retval->name));
166 INIT_LIST_HEAD(&retval->page_list);
167 spin_lock_init(&retval->lock);
169 retval->boundary = boundary;
170 retval->allocation = allocation;
175 mutex_lock(&pools_lock);
176 if (list_empty(&dev->dma_pools))
177 ret = device_create_file(dev, &dev_attr_pools);
180 /* note: not currently insisting "name" be unique */
182 list_add(&retval->pools, &dev->dma_pools);
187 mutex_unlock(&pools_lock);
189 INIT_LIST_HEAD(&retval->pools);
193 EXPORT_SYMBOL(dma_pool_create);
195 static void pool_initialise_page(struct dma_pool *pool, struct dma_page *page)
197 unsigned int offset = 0;
198 unsigned int next_boundary = pool->boundary;
201 unsigned int next = offset + pool->size;
202 if (unlikely((next + pool->size) >= next_boundary)) {
203 next = next_boundary;
204 next_boundary += pool->boundary;
206 *(int *)(page->vaddr + offset) = next;
208 } while (offset < pool->allocation);
211 static struct dma_page *pool_alloc_page(struct dma_pool *pool, gfp_t mem_flags)
213 struct dma_page *page;
215 page = kmalloc(sizeof(*page), mem_flags);
218 page->vaddr = dma_alloc_coherent(pool->dev, pool->allocation,
219 &page->dma, mem_flags);
222 memset(page->vaddr, POOL_POISON_FREED, pool->allocation);
224 pool_initialise_page(pool, page);
234 static inline int is_page_busy(struct dma_page *page)
236 return page->in_use != 0;
239 static void pool_free_page(struct dma_pool *pool, struct dma_page *page)
241 dma_addr_t dma = page->dma;
244 memset(page->vaddr, POOL_POISON_FREED, pool->allocation);
246 dma_free_coherent(pool->dev, pool->allocation, page->vaddr, dma);
247 list_del(&page->page_list);
252 * dma_pool_destroy - destroys a pool of dma memory blocks.
253 * @pool: dma pool that will be destroyed
254 * Context: !in_interrupt()
256 * Caller guarantees that no more memory from the pool is in use,
257 * and that nothing will try to use the pool after this call.
259 void dma_pool_destroy(struct dma_pool *pool)
261 mutex_lock(&pools_lock);
262 list_del(&pool->pools);
263 if (pool->dev && list_empty(&pool->dev->dma_pools))
264 device_remove_file(pool->dev, &dev_attr_pools);
265 mutex_unlock(&pools_lock);
267 while (!list_empty(&pool->page_list)) {
268 struct dma_page *page;
269 page = list_entry(pool->page_list.next,
270 struct dma_page, page_list);
271 if (is_page_busy(page)) {
274 "dma_pool_destroy %s, %p busy\n",
275 pool->name, page->vaddr);
278 "dma_pool_destroy %s, %p busy\n",
279 pool->name, page->vaddr);
280 /* leak the still-in-use consistent memory */
281 list_del(&page->page_list);
284 pool_free_page(pool, page);
289 EXPORT_SYMBOL(dma_pool_destroy);
292 * dma_pool_alloc - get a block of consistent memory
293 * @pool: dma pool that will produce the block
294 * @mem_flags: GFP_* bitmask
295 * @handle: pointer to dma address of block
297 * This returns the kernel virtual address of a currently unused block,
298 * and reports its dma address through the handle.
299 * If such a memory block can't be allocated, %NULL is returned.
301 void *dma_pool_alloc(struct dma_pool *pool, gfp_t mem_flags,
305 struct dma_page *page;
309 might_sleep_if(mem_flags & __GFP_WAIT);
311 spin_lock_irqsave(&pool->lock, flags);
312 list_for_each_entry(page, &pool->page_list, page_list) {
313 if (page->offset < pool->allocation)
317 /* pool_alloc_page() might sleep, so temporarily drop &pool->lock */
318 spin_unlock_irqrestore(&pool->lock, flags);
320 page = pool_alloc_page(pool, mem_flags);
324 spin_lock_irqsave(&pool->lock, flags);
326 list_add(&page->page_list, &pool->page_list);
329 offset = page->offset;
330 page->offset = *(int *)(page->vaddr + offset);
331 retval = offset + page->vaddr;
332 *handle = offset + page->dma;
334 memset(retval, POOL_POISON_ALLOCATED, pool->size);
336 spin_unlock_irqrestore(&pool->lock, flags);
339 EXPORT_SYMBOL(dma_pool_alloc);
341 static struct dma_page *pool_find_page(struct dma_pool *pool, dma_addr_t dma)
343 struct dma_page *page;
345 list_for_each_entry(page, &pool->page_list, page_list) {
348 if (dma < (page->dma + pool->allocation))
355 * dma_pool_free - put block back into dma pool
356 * @pool: the dma pool holding the block
357 * @vaddr: virtual address of block
358 * @dma: dma address of block
360 * Caller promises neither device nor driver will again touch this block
361 * unless it is first re-allocated.
363 void dma_pool_free(struct dma_pool *pool, void *vaddr, dma_addr_t dma)
365 struct dma_page *page;
369 spin_lock_irqsave(&pool->lock, flags);
370 page = pool_find_page(pool, dma);
372 spin_unlock_irqrestore(&pool->lock, flags);
375 "dma_pool_free %s, %p/%lx (bad dma)\n",
376 pool->name, vaddr, (unsigned long)dma);
378 printk(KERN_ERR "dma_pool_free %s, %p/%lx (bad dma)\n",
379 pool->name, vaddr, (unsigned long)dma);
383 offset = vaddr - page->vaddr;
385 if ((dma - page->dma) != offset) {
386 spin_unlock_irqrestore(&pool->lock, flags);
389 "dma_pool_free %s, %p (bad vaddr)/%Lx\n",
390 pool->name, vaddr, (unsigned long long)dma);
393 "dma_pool_free %s, %p (bad vaddr)/%Lx\n",
394 pool->name, vaddr, (unsigned long long)dma);
398 unsigned int chain = page->offset;
399 while (chain < pool->allocation) {
400 if (chain != offset) {
401 chain = *(int *)(page->vaddr + chain);
404 spin_unlock_irqrestore(&pool->lock, flags);
406 dev_err(pool->dev, "dma_pool_free %s, dma %Lx "
407 "already free\n", pool->name,
408 (unsigned long long)dma);
410 printk(KERN_ERR "dma_pool_free %s, dma %Lx "
411 "already free\n", pool->name,
412 (unsigned long long)dma);
416 memset(vaddr, POOL_POISON_FREED, pool->size);
420 *(int *)vaddr = page->offset;
421 page->offset = offset;
423 * Resist a temptation to do
424 * if (!is_page_busy(page)) pool_free_page(pool, page);
425 * Better have a few empty pages hang around.
427 spin_unlock_irqrestore(&pool->lock, flags);
429 EXPORT_SYMBOL(dma_pool_free);
434 static void dmam_pool_release(struct device *dev, void *res)
436 struct dma_pool *pool = *(struct dma_pool **)res;
438 dma_pool_destroy(pool);
441 static int dmam_pool_match(struct device *dev, void *res, void *match_data)
443 return *(struct dma_pool **)res == match_data;
447 * dmam_pool_create - Managed dma_pool_create()
448 * @name: name of pool, for diagnostics
449 * @dev: device that will be doing the DMA
450 * @size: size of the blocks in this pool.
451 * @align: alignment requirement for blocks; must be a power of two
452 * @allocation: returned blocks won't cross this boundary (or zero)
454 * Managed dma_pool_create(). DMA pool created with this function is
455 * automatically destroyed on driver detach.
457 struct dma_pool *dmam_pool_create(const char *name, struct device *dev,
458 size_t size, size_t align, size_t allocation)
460 struct dma_pool **ptr, *pool;
462 ptr = devres_alloc(dmam_pool_release, sizeof(*ptr), GFP_KERNEL);
466 pool = *ptr = dma_pool_create(name, dev, size, align, allocation);
468 devres_add(dev, ptr);
474 EXPORT_SYMBOL(dmam_pool_create);
477 * dmam_pool_destroy - Managed dma_pool_destroy()
478 * @pool: dma pool that will be destroyed
480 * Managed dma_pool_destroy().
482 void dmam_pool_destroy(struct dma_pool *pool)
484 struct device *dev = pool->dev;
486 dma_pool_destroy(pool);
487 WARN_ON(devres_destroy(dev, dmam_pool_release, dmam_pool_match, pool));
489 EXPORT_SYMBOL(dmam_pool_destroy);