1 /*
2 * DMA Pool allocator
3 *
4 * Copyright 2001 David Brownell
5 * Copyright 2007 Intel Corporation
6 * Author: Matthew Wilcox <willy@linux.intel.com>
7 *
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.
11 *
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.
16 *
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.
23 */
24
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>
40
41 #if defined(CONFIG_DEBUG_SLAB) || defined(CONFIG_SLUB_DEBUG_ON)
42 #define DMAPOOL_DEBUG 1
43 #endif
44
45 struct dma_pool { /* the pool */
46 struct list_head page_list;
47 spinlock_t lock;
48 size_t size;
49 struct device *dev;
50 size_t allocation;
51 size_t boundary;
52 char name[32];
53 struct list_head pools;
54 };
55
56 struct dma_page { /* cacheable header for 'allocation' bytes */
57 struct list_head page_list;
58 void *vaddr;
59 dma_addr_t dma;
60 unsigned int in_use;
61 unsigned int offset;
62 };
63
64 static DEFINE_MUTEX(pools_lock);
65 static DEFINE_MUTEX(pools_reg_lock);
66
67 static ssize_t
show_pools(struct device * dev,struct device_attribute * attr,char * buf)68 show_pools(struct device *dev, struct device_attribute *attr, char *buf)
69 {
70 unsigned temp;
71 unsigned size;
72 char *next;
73 struct dma_page *page;
74 struct dma_pool *pool;
75
76 next = buf;
77 size = PAGE_SIZE;
78
79 temp = scnprintf(next, size, "poolinfo - 0.1\n");
80 size -= temp;
81 next += temp;
82
83 mutex_lock(&pools_lock);
84 list_for_each_entry(pool, &dev->dma_pools, pools) {
85 unsigned pages = 0;
86 unsigned blocks = 0;
87
88 spin_lock_irq(&pool->lock);
89 list_for_each_entry(page, &pool->page_list, page_list) {
90 pages++;
91 blocks += page->in_use;
92 }
93 spin_unlock_irq(&pool->lock);
94
95 /* per-pool info, no real statistics yet */
96 temp = scnprintf(next, size, "%-16s %4u %4Zu %4Zu %2u\n",
97 pool->name, blocks,
98 pages * (pool->allocation / pool->size),
99 pool->size, pages);
100 size -= temp;
101 next += temp;
102 }
103 mutex_unlock(&pools_lock);
104
105 return PAGE_SIZE - size;
106 }
107
108 static DEVICE_ATTR(pools, S_IRUGO, show_pools, NULL);
109
110 /**
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()
118 *
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.
125 *
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.
130 */
dma_pool_create(const char * name,struct device * dev,size_t size,size_t align,size_t boundary)131 struct dma_pool *dma_pool_create(const char *name, struct device *dev,
132 size_t size, size_t align, size_t boundary)
133 {
134 struct dma_pool *retval;
135 size_t allocation;
136 bool empty = false;
137
138 if (align == 0)
139 align = 1;
140 else if (align & (align - 1))
141 return NULL;
142
143 if (size == 0)
144 return NULL;
145 else if (size < 4)
146 size = 4;
147
148 if ((size % align) != 0)
149 size = ALIGN(size, align);
150
151 allocation = max_t(size_t, size, PAGE_SIZE);
152
153 if (!boundary)
154 boundary = allocation;
155 else if ((boundary < size) || (boundary & (boundary - 1)))
156 return NULL;
157
158 retval = kmalloc_node(sizeof(*retval), GFP_KERNEL, dev_to_node(dev));
159 if (!retval)
160 return retval;
161
162 strlcpy(retval->name, name, sizeof(retval->name));
163
164 retval->dev = dev;
165
166 INIT_LIST_HEAD(&retval->page_list);
167 spin_lock_init(&retval->lock);
168 retval->size = size;
169 retval->boundary = boundary;
170 retval->allocation = allocation;
171
172 INIT_LIST_HEAD(&retval->pools);
173
174 /*
175 * pools_lock ensures that the ->dma_pools list does not get corrupted.
176 * pools_reg_lock ensures that there is not a race between
177 * dma_pool_create() and dma_pool_destroy() or within dma_pool_create()
178 * when the first invocation of dma_pool_create() failed on
179 * device_create_file() and the second assumes that it has been done (I
180 * know it is a short window).
181 */
182 mutex_lock(&pools_reg_lock);
183 mutex_lock(&pools_lock);
184 if (list_empty(&dev->dma_pools))
185 empty = true;
186 list_add(&retval->pools, &dev->dma_pools);
187 mutex_unlock(&pools_lock);
188 if (empty) {
189 int err;
190
191 err = device_create_file(dev, &dev_attr_pools);
192 if (err) {
193 mutex_lock(&pools_lock);
194 list_del(&retval->pools);
195 mutex_unlock(&pools_lock);
196 mutex_unlock(&pools_reg_lock);
197 kfree(retval);
198 return NULL;
199 }
200 }
201 mutex_unlock(&pools_reg_lock);
202 return retval;
203 }
204 EXPORT_SYMBOL(dma_pool_create);
205
pool_initialise_page(struct dma_pool * pool,struct dma_page * page)206 static void pool_initialise_page(struct dma_pool *pool, struct dma_page *page)
207 {
208 unsigned int offset = 0;
209 unsigned int next_boundary = pool->boundary;
210
211 do {
212 unsigned int next = offset + pool->size;
213 if (unlikely((next + pool->size) >= next_boundary)) {
214 next = next_boundary;
215 next_boundary += pool->boundary;
216 }
217 *(int *)(page->vaddr + offset) = next;
218 offset = next;
219 } while (offset < pool->allocation);
220 }
221
pool_alloc_page(struct dma_pool * pool,gfp_t mem_flags)222 static struct dma_page *pool_alloc_page(struct dma_pool *pool, gfp_t mem_flags)
223 {
224 struct dma_page *page;
225
226 page = kmalloc(sizeof(*page), mem_flags);
227 if (!page)
228 return NULL;
229 page->vaddr = dma_alloc_coherent(pool->dev, pool->allocation,
230 &page->dma, mem_flags);
231 if (page->vaddr) {
232 #ifdef DMAPOOL_DEBUG
233 memset(page->vaddr, POOL_POISON_FREED, pool->allocation);
234 #endif
235 pool_initialise_page(pool, page);
236 page->in_use = 0;
237 page->offset = 0;
238 } else {
239 kfree(page);
240 page = NULL;
241 }
242 return page;
243 }
244
is_page_busy(struct dma_page * page)245 static inline int is_page_busy(struct dma_page *page)
246 {
247 return page->in_use != 0;
248 }
249
pool_free_page(struct dma_pool * pool,struct dma_page * page)250 static void pool_free_page(struct dma_pool *pool, struct dma_page *page)
251 {
252 dma_addr_t dma = page->dma;
253
254 #ifdef DMAPOOL_DEBUG
255 memset(page->vaddr, POOL_POISON_FREED, pool->allocation);
256 #endif
257 dma_free_coherent(pool->dev, pool->allocation, page->vaddr, dma);
258 list_del(&page->page_list);
259 kfree(page);
260 }
261
262 /**
263 * dma_pool_destroy - destroys a pool of dma memory blocks.
264 * @pool: dma pool that will be destroyed
265 * Context: !in_interrupt()
266 *
267 * Caller guarantees that no more memory from the pool is in use,
268 * and that nothing will try to use the pool after this call.
269 */
dma_pool_destroy(struct dma_pool * pool)270 void dma_pool_destroy(struct dma_pool *pool)
271 {
272 bool empty = false;
273
274 mutex_lock(&pools_reg_lock);
275 mutex_lock(&pools_lock);
276 list_del(&pool->pools);
277 if (pool->dev && list_empty(&pool->dev->dma_pools))
278 empty = true;
279 mutex_unlock(&pools_lock);
280 if (empty)
281 device_remove_file(pool->dev, &dev_attr_pools);
282 mutex_unlock(&pools_reg_lock);
283
284 while (!list_empty(&pool->page_list)) {
285 struct dma_page *page;
286 page = list_entry(pool->page_list.next,
287 struct dma_page, page_list);
288 if (is_page_busy(page)) {
289 if (pool->dev)
290 dev_err(pool->dev,
291 "dma_pool_destroy %s, %p busy\n",
292 pool->name, page->vaddr);
293 else
294 printk(KERN_ERR
295 "dma_pool_destroy %s, %p busy\n",
296 pool->name, page->vaddr);
297 /* leak the still-in-use consistent memory */
298 list_del(&page->page_list);
299 kfree(page);
300 } else
301 pool_free_page(pool, page);
302 }
303
304 kfree(pool);
305 }
306 EXPORT_SYMBOL(dma_pool_destroy);
307
308 /**
309 * dma_pool_alloc - get a block of consistent memory
310 * @pool: dma pool that will produce the block
311 * @mem_flags: GFP_* bitmask
312 * @handle: pointer to dma address of block
313 *
314 * This returns the kernel virtual address of a currently unused block,
315 * and reports its dma address through the handle.
316 * If such a memory block can't be allocated, %NULL is returned.
317 */
dma_pool_alloc(struct dma_pool * pool,gfp_t mem_flags,dma_addr_t * handle)318 void *dma_pool_alloc(struct dma_pool *pool, gfp_t mem_flags,
319 dma_addr_t *handle)
320 {
321 unsigned long flags;
322 struct dma_page *page;
323 size_t offset;
324 void *retval;
325
326 might_sleep_if(mem_flags & __GFP_WAIT);
327
328 spin_lock_irqsave(&pool->lock, flags);
329 list_for_each_entry(page, &pool->page_list, page_list) {
330 if (page->offset < pool->allocation)
331 goto ready;
332 }
333
334 /* pool_alloc_page() might sleep, so temporarily drop &pool->lock */
335 spin_unlock_irqrestore(&pool->lock, flags);
336
337 page = pool_alloc_page(pool, mem_flags);
338 if (!page)
339 return NULL;
340
341 spin_lock_irqsave(&pool->lock, flags);
342
343 list_add(&page->page_list, &pool->page_list);
344 ready:
345 page->in_use++;
346 offset = page->offset;
347 page->offset = *(int *)(page->vaddr + offset);
348 retval = offset + page->vaddr;
349 *handle = offset + page->dma;
350 #ifdef DMAPOOL_DEBUG
351 {
352 int i;
353 u8 *data = retval;
354 /* page->offset is stored in first 4 bytes */
355 for (i = sizeof(page->offset); i < pool->size; i++) {
356 if (data[i] == POOL_POISON_FREED)
357 continue;
358 if (pool->dev)
359 dev_err(pool->dev,
360 "dma_pool_alloc %s, %p (corrupted)\n",
361 pool->name, retval);
362 else
363 pr_err("dma_pool_alloc %s, %p (corrupted)\n",
364 pool->name, retval);
365
366 /*
367 * Dump the first 4 bytes even if they are not
368 * POOL_POISON_FREED
369 */
370 print_hex_dump(KERN_ERR, "", DUMP_PREFIX_OFFSET, 16, 1,
371 data, pool->size, 1);
372 break;
373 }
374 }
375 memset(retval, POOL_POISON_ALLOCATED, pool->size);
376 #endif
377 spin_unlock_irqrestore(&pool->lock, flags);
378 return retval;
379 }
380 EXPORT_SYMBOL(dma_pool_alloc);
381
pool_find_page(struct dma_pool * pool,dma_addr_t dma)382 static struct dma_page *pool_find_page(struct dma_pool *pool, dma_addr_t dma)
383 {
384 struct dma_page *page;
385
386 list_for_each_entry(page, &pool->page_list, page_list) {
387 if (dma < page->dma)
388 continue;
389 if (dma < (page->dma + pool->allocation))
390 return page;
391 }
392 return NULL;
393 }
394
395 /**
396 * dma_pool_free - put block back into dma pool
397 * @pool: the dma pool holding the block
398 * @vaddr: virtual address of block
399 * @dma: dma address of block
400 *
401 * Caller promises neither device nor driver will again touch this block
402 * unless it is first re-allocated.
403 */
dma_pool_free(struct dma_pool * pool,void * vaddr,dma_addr_t dma)404 void dma_pool_free(struct dma_pool *pool, void *vaddr, dma_addr_t dma)
405 {
406 struct dma_page *page;
407 unsigned long flags;
408 unsigned int offset;
409
410 spin_lock_irqsave(&pool->lock, flags);
411 page = pool_find_page(pool, dma);
412 if (!page) {
413 spin_unlock_irqrestore(&pool->lock, flags);
414 if (pool->dev)
415 dev_err(pool->dev,
416 "dma_pool_free %s, %p/%lx (bad dma)\n",
417 pool->name, vaddr, (unsigned long)dma);
418 else
419 printk(KERN_ERR "dma_pool_free %s, %p/%lx (bad dma)\n",
420 pool->name, vaddr, (unsigned long)dma);
421 return;
422 }
423
424 offset = vaddr - page->vaddr;
425 #ifdef DMAPOOL_DEBUG
426 if ((dma - page->dma) != offset) {
427 spin_unlock_irqrestore(&pool->lock, flags);
428 if (pool->dev)
429 dev_err(pool->dev,
430 "dma_pool_free %s, %p (bad vaddr)/%Lx\n",
431 pool->name, vaddr, (unsigned long long)dma);
432 else
433 printk(KERN_ERR
434 "dma_pool_free %s, %p (bad vaddr)/%Lx\n",
435 pool->name, vaddr, (unsigned long long)dma);
436 return;
437 }
438 {
439 unsigned int chain = page->offset;
440 while (chain < pool->allocation) {
441 if (chain != offset) {
442 chain = *(int *)(page->vaddr + chain);
443 continue;
444 }
445 spin_unlock_irqrestore(&pool->lock, flags);
446 if (pool->dev)
447 dev_err(pool->dev, "dma_pool_free %s, dma %Lx "
448 "already free\n", pool->name,
449 (unsigned long long)dma);
450 else
451 printk(KERN_ERR "dma_pool_free %s, dma %Lx "
452 "already free\n", pool->name,
453 (unsigned long long)dma);
454 return;
455 }
456 }
457 memset(vaddr, POOL_POISON_FREED, pool->size);
458 #endif
459
460 page->in_use--;
461 *(int *)vaddr = page->offset;
462 page->offset = offset;
463 /*
464 * Resist a temptation to do
465 * if (!is_page_busy(page)) pool_free_page(pool, page);
466 * Better have a few empty pages hang around.
467 */
468 spin_unlock_irqrestore(&pool->lock, flags);
469 }
470 EXPORT_SYMBOL(dma_pool_free);
471
472 /*
473 * Managed DMA pool
474 */
dmam_pool_release(struct device * dev,void * res)475 static void dmam_pool_release(struct device *dev, void *res)
476 {
477 struct dma_pool *pool = *(struct dma_pool **)res;
478
479 dma_pool_destroy(pool);
480 }
481
dmam_pool_match(struct device * dev,void * res,void * match_data)482 static int dmam_pool_match(struct device *dev, void *res, void *match_data)
483 {
484 return *(struct dma_pool **)res == match_data;
485 }
486
487 /**
488 * dmam_pool_create - Managed dma_pool_create()
489 * @name: name of pool, for diagnostics
490 * @dev: device that will be doing the DMA
491 * @size: size of the blocks in this pool.
492 * @align: alignment requirement for blocks; must be a power of two
493 * @allocation: returned blocks won't cross this boundary (or zero)
494 *
495 * Managed dma_pool_create(). DMA pool created with this function is
496 * automatically destroyed on driver detach.
497 */
dmam_pool_create(const char * name,struct device * dev,size_t size,size_t align,size_t allocation)498 struct dma_pool *dmam_pool_create(const char *name, struct device *dev,
499 size_t size, size_t align, size_t allocation)
500 {
501 struct dma_pool **ptr, *pool;
502
503 ptr = devres_alloc(dmam_pool_release, sizeof(*ptr), GFP_KERNEL);
504 if (!ptr)
505 return NULL;
506
507 pool = *ptr = dma_pool_create(name, dev, size, align, allocation);
508 if (pool)
509 devres_add(dev, ptr);
510 else
511 devres_free(ptr);
512
513 return pool;
514 }
515 EXPORT_SYMBOL(dmam_pool_create);
516
517 /**
518 * dmam_pool_destroy - Managed dma_pool_destroy()
519 * @pool: dma pool that will be destroyed
520 *
521 * Managed dma_pool_destroy().
522 */
dmam_pool_destroy(struct dma_pool * pool)523 void dmam_pool_destroy(struct dma_pool *pool)
524 {
525 struct device *dev = pool->dev;
526
527 WARN_ON(devres_release(dev, dmam_pool_release, dmam_pool_match, pool));
528 }
529 EXPORT_SYMBOL(dmam_pool_destroy);
530