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
45struct 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
56struct 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
64static DEFINE_MUTEX(pools_lock);
65static DEFINE_MUTEX(pools_reg_lock);
66
67static ssize_t
68show_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
108static DEVICE_ATTR(pools, 0444, 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: not in_interrupt()
118 *
119 * 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.
124 *
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.
129 *
130 * Return: a dma allocation pool with the requested characteristics, or
131 * %NULL if one can't be created.
132 */
133struct dma_pool *dma_pool_create(const char *name, struct device *dev,
134 size_t size, size_t align, size_t boundary)
135{
136 struct dma_pool *retval;
137 size_t allocation;
138 bool empty = false;
139
140 if (align == 0)
141 align = 1;
142 else if (align & (align - 1))
143 return NULL;
144
145 if (size == 0)
146 return NULL;
147 else if (size < 4)
148 size = 4;
149
150 if ((size % align) != 0)
151 size = ALIGN(size, align);
152
153 allocation = max_t(size_t, size, PAGE_SIZE);
154
155 if (!boundary)
156 boundary = allocation;
157 else if ((boundary < size) || (boundary & (boundary - 1)))
158 return NULL;
159
160 retval = kmalloc_node(sizeof(*retval), GFP_KERNEL, dev_to_node(dev));
161 if (!retval)
162 return retval;
163
164 strlcpy(retval->name, name, sizeof(retval->name));
165
166 retval->dev = dev;
167
168 INIT_LIST_HEAD(&retval->page_list);
169 spin_lock_init(&retval->lock);
170 retval->size = size;
171 retval->boundary = boundary;
172 retval->allocation = allocation;
173
174 INIT_LIST_HEAD(&retval->pools);
175
176 /*
177 * pools_lock ensures that the ->dma_pools list does not get corrupted.
178 * pools_reg_lock ensures that there is not a race between
179 * dma_pool_create() and dma_pool_destroy() or within dma_pool_create()
180 * when the first invocation of dma_pool_create() failed on
181 * device_create_file() and the second assumes that it has been done (I
182 * know it is a short window).
183 */
184 mutex_lock(&pools_reg_lock);
185 mutex_lock(&pools_lock);
186 if (list_empty(&dev->dma_pools))
187 empty = true;
188 list_add(&retval->pools, &dev->dma_pools);
189 mutex_unlock(&pools_lock);
190 if (empty) {
191 int err;
192
193 err = device_create_file(dev, &dev_attr_pools);
194 if (err) {
195 mutex_lock(&pools_lock);
196 list_del(&retval->pools);
197 mutex_unlock(&pools_lock);
198 mutex_unlock(&pools_reg_lock);
199 kfree(retval);
200 return NULL;
201 }
202 }
203 mutex_unlock(&pools_reg_lock);
204 return retval;
205}
206EXPORT_SYMBOL(dma_pool_create);
207
208static void pool_initialise_page(struct dma_pool *pool, struct dma_page *page)
209{
210 unsigned int offset = 0;
211 unsigned int next_boundary = pool->boundary;
212
213 do {
214 unsigned int next = offset + pool->size;
215 if (unlikely((next + pool->size) >= next_boundary)) {
216 next = next_boundary;
217 next_boundary += pool->boundary;
218 }
219 *(int *)(page->vaddr + offset) = next;
220 offset = next;
221 } while (offset < pool->allocation);
222}
223
224static struct dma_page *pool_alloc_page(struct dma_pool *pool, gfp_t mem_flags)
225{
226 struct dma_page *page;
227
228 page = kmalloc(sizeof(*page), mem_flags);
229 if (!page)
230 return NULL;
231 page->vaddr = dma_alloc_coherent(pool->dev, pool->allocation,
232 &page->dma, mem_flags);
233 if (page->vaddr) {
234#ifdef DMAPOOL_DEBUG
235 memset(page->vaddr, POOL_POISON_FREED, pool->allocation);
236#endif
237 pool_initialise_page(pool, page);
238 page->in_use = 0;
239 page->offset = 0;
240 } else {
241 kfree(page);
242 page = NULL;
243 }
244 return page;
245}
246
247static inline bool is_page_busy(struct dma_page *page)
248{
249 return page->in_use != 0;
250}
251
252static void pool_free_page(struct dma_pool *pool, struct dma_page *page)
253{
254 dma_addr_t dma = page->dma;
255
256#ifdef DMAPOOL_DEBUG
257 memset(page->vaddr, POOL_POISON_FREED, pool->allocation);
258#endif
259 dma_free_coherent(pool->dev, pool->allocation, page->vaddr, dma);
260 list_del(&page->page_list);
261 kfree(page);
262}
263
264/**
265 * dma_pool_destroy - destroys a pool of dma memory blocks.
266 * @pool: dma pool that will be destroyed
267 * Context: !in_interrupt()
268 *
269 * Caller guarantees that no more memory from the pool is in use,
270 * and that nothing will try to use the pool after this call.
271 */
272void dma_pool_destroy(struct dma_pool *pool)
273{
274 bool empty = false;
275
276 if (unlikely(!pool))
277 return;
278
279 mutex_lock(&pools_reg_lock);
280 mutex_lock(&pools_lock);
281 list_del(&pool->pools);
282 if (pool->dev && list_empty(&pool->dev->dma_pools))
283 empty = true;
284 mutex_unlock(&pools_lock);
285 if (empty)
286 device_remove_file(pool->dev, &dev_attr_pools);
287 mutex_unlock(&pools_reg_lock);
288
289 while (!list_empty(&pool->page_list)) {
290 struct dma_page *page;
291 page = list_entry(pool->page_list.next,
292 struct dma_page, page_list);
293 if (is_page_busy(page)) {
294 if (pool->dev)
295 dev_err(pool->dev,
296 "dma_pool_destroy %s, %p busy\n",
297 pool->name, page->vaddr);
298 else
299 pr_err("dma_pool_destroy %s, %p busy\n",
300 pool->name, page->vaddr);
301 /* leak the still-in-use consistent memory */
302 list_del(&page->page_list);
303 kfree(page);
304 } else
305 pool_free_page(pool, page);
306 }
307
308 kfree(pool);
309}
310EXPORT_SYMBOL(dma_pool_destroy);
311
312/**
313 * dma_pool_alloc - get a block of consistent memory
314 * @pool: dma pool that will produce the block
315 * @mem_flags: GFP_* bitmask
316 * @handle: pointer to dma address of block
317 *
318 * Return: the kernel virtual address of a currently unused block,
319 * and reports its dma address through the handle.
320 * If such a memory block can't be allocated, %NULL is returned.
321 */
322void *dma_pool_alloc(struct dma_pool *pool, gfp_t mem_flags,
323 dma_addr_t *handle)
324{
325 unsigned long flags;
326 struct dma_page *page;
327 size_t offset;
328 void *retval;
329
330 might_sleep_if(gfpflags_allow_blocking(mem_flags));
331
332 spin_lock_irqsave(&pool->lock, flags);
333 list_for_each_entry(page, &pool->page_list, page_list) {
334 if (page->offset < pool->allocation)
335 goto ready;
336 }
337
338 /* pool_alloc_page() might sleep, so temporarily drop &pool->lock */
339 spin_unlock_irqrestore(&pool->lock, flags);
340
341 page = pool_alloc_page(pool, mem_flags & (~__GFP_ZERO));
342 if (!page)
343 return NULL;
344
345 spin_lock_irqsave(&pool->lock, flags);
346
347 list_add(&page->page_list, &pool->page_list);
348 ready:
349 page->in_use++;
350 offset = page->offset;
351 page->offset = *(int *)(page->vaddr + offset);
352 retval = offset + page->vaddr;
353 *handle = offset + page->dma;
354#ifdef DMAPOOL_DEBUG
355 {
356 int i;
357 u8 *data = retval;
358 /* page->offset is stored in first 4 bytes */
359 for (i = sizeof(page->offset); i < pool->size; i++) {
360 if (data[i] == POOL_POISON_FREED)
361 continue;
362 if (pool->dev)
363 dev_err(pool->dev,
364 "dma_pool_alloc %s, %p (corrupted)\n",
365 pool->name, retval);
366 else
367 pr_err("dma_pool_alloc %s, %p (corrupted)\n",
368 pool->name, retval);
369
370 /*
371 * Dump the first 4 bytes even if they are not
372 * POOL_POISON_FREED
373 */
374 print_hex_dump(KERN_ERR, "", DUMP_PREFIX_OFFSET, 16, 1,
375 data, pool->size, 1);
376 break;
377 }
378 }
379 if (!(mem_flags & __GFP_ZERO))
380 memset(retval, POOL_POISON_ALLOCATED, pool->size);
381#endif
382 spin_unlock_irqrestore(&pool->lock, flags);
383
384 if (mem_flags & __GFP_ZERO)
385 memset(retval, 0, pool->size);
386
387 return retval;
388}
389EXPORT_SYMBOL(dma_pool_alloc);
390
391static struct dma_page *pool_find_page(struct dma_pool *pool, dma_addr_t dma)
392{
393 struct dma_page *page;
394
395 list_for_each_entry(page, &pool->page_list, page_list) {
396 if (dma < page->dma)
397 continue;
398 if ((dma - page->dma) < pool->allocation)
399 return page;
400 }
401 return NULL;
402}
403
404/**
405 * dma_pool_free - put block back into dma pool
406 * @pool: the dma pool holding the block
407 * @vaddr: virtual address of block
408 * @dma: dma address of block
409 *
410 * Caller promises neither device nor driver will again touch this block
411 * unless it is first re-allocated.
412 */
413void dma_pool_free(struct dma_pool *pool, void *vaddr, dma_addr_t dma)
414{
415 struct dma_page *page;
416 unsigned long flags;
417 unsigned int offset;
418
419 spin_lock_irqsave(&pool->lock, flags);
420 page = pool_find_page(pool, dma);
421 if (!page) {
422 spin_unlock_irqrestore(&pool->lock, flags);
423 if (pool->dev)
424 dev_err(pool->dev,
425 "dma_pool_free %s, %p/%lx (bad dma)\n",
426 pool->name, vaddr, (unsigned long)dma);
427 else
428 pr_err("dma_pool_free %s, %p/%lx (bad dma)\n",
429 pool->name, vaddr, (unsigned long)dma);
430 return;
431 }
432
433 offset = vaddr - page->vaddr;
434#ifdef DMAPOOL_DEBUG
435 if ((dma - page->dma) != offset) {
436 spin_unlock_irqrestore(&pool->lock, flags);
437 if (pool->dev)
438 dev_err(pool->dev,
439 "dma_pool_free %s, %p (bad vaddr)/%pad\n",
440 pool->name, vaddr, &dma);
441 else
442 pr_err("dma_pool_free %s, %p (bad vaddr)/%pad\n",
443 pool->name, vaddr, &dma);
444 return;
445 }
446 {
447 unsigned int chain = page->offset;
448 while (chain < pool->allocation) {
449 if (chain != offset) {
450 chain = *(int *)(page->vaddr + chain);
451 continue;
452 }
453 spin_unlock_irqrestore(&pool->lock, flags);
454 if (pool->dev)
455 dev_err(pool->dev, "dma_pool_free %s, dma %pad already free\n",
456 pool->name, &dma);
457 else
458 pr_err("dma_pool_free %s, dma %pad already free\n",
459 pool->name, &dma);
460 return;
461 }
462 }
463 memset(vaddr, POOL_POISON_FREED, pool->size);
464#endif
465
466 page->in_use--;
467 *(int *)vaddr = page->offset;
468 page->offset = offset;
469 /*
470 * Resist a temptation to do
471 * if (!is_page_busy(page)) pool_free_page(pool, page);
472 * Better have a few empty pages hang around.
473 */
474 spin_unlock_irqrestore(&pool->lock, flags);
475}
476EXPORT_SYMBOL(dma_pool_free);
477
478/*
479 * Managed DMA pool
480 */
481static void dmam_pool_release(struct device *dev, void *res)
482{
483 struct dma_pool *pool = *(struct dma_pool **)res;
484
485 dma_pool_destroy(pool);
486}
487
488static int dmam_pool_match(struct device *dev, void *res, void *match_data)
489{
490 return *(struct dma_pool **)res == match_data;
491}
492
493/**
494 * dmam_pool_create - Managed dma_pool_create()
495 * @name: name of pool, for diagnostics
496 * @dev: device that will be doing the DMA
497 * @size: size of the blocks in this pool.
498 * @align: alignment requirement for blocks; must be a power of two
499 * @allocation: returned blocks won't cross this boundary (or zero)
500 *
501 * Managed dma_pool_create(). DMA pool created with this function is
502 * automatically destroyed on driver detach.
503 *
504 * Return: a managed dma allocation pool with the requested
505 * characteristics, or %NULL if one can't be created.
506 */
507struct dma_pool *dmam_pool_create(const char *name, struct device *dev,
508 size_t size, size_t align, size_t allocation)
509{
510 struct dma_pool **ptr, *pool;
511
512 ptr = devres_alloc(dmam_pool_release, sizeof(*ptr), GFP_KERNEL);
513 if (!ptr)
514 return NULL;
515
516 pool = *ptr = dma_pool_create(name, dev, size, align, allocation);
517 if (pool)
518 devres_add(dev, ptr);
519 else
520 devres_free(ptr);
521
522 return pool;
523}
524EXPORT_SYMBOL(dmam_pool_create);
525
526/**
527 * dmam_pool_destroy - Managed dma_pool_destroy()
528 * @pool: dma pool that will be destroyed
529 *
530 * Managed dma_pool_destroy().
531 */
532void dmam_pool_destroy(struct dma_pool *pool)
533{
534 struct device *dev = pool->dev;
535
536 WARN_ON(devres_release(dev, dmam_pool_release, dmam_pool_match, pool));
537}
538EXPORT_SYMBOL(dmam_pool_destroy);
539