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1/*
2 * DMA Pool allocator
3 *
4 * Copyright 2001 David Brownell
5 * Copyright 2007 Intel Corporation
6 * Author: Matthew Wilcox <[email protected]>
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, 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 */
131struct 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}
204EXPORT_SYMBOL(dma_pool_create);
205
206static 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
222static 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
245static inline bool is_page_busy(struct dma_page *page)
246{
247 return page->in_use != 0;
248}
249
250static 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 */
270void dma_pool_destroy(struct dma_pool *pool)
271{
272 bool empty = false;
273
274 if (unlikely(!pool))
275 return;
276
277 mutex_lock(&pools_reg_lock);
278 mutex_lock(&pools_lock);
279 list_del(&pool->pools);
280 if (pool->dev && list_empty(&pool->dev->dma_pools))
281 empty = true;
282 mutex_unlock(&pools_lock);
283 if (empty)
284 device_remove_file(pool->dev, &dev_attr_pools);
285 mutex_unlock(&pools_reg_lock);
286
287 while (!list_empty(&pool->page_list)) {
288 struct dma_page *page;
289 page = list_entry(pool->page_list.next,
290 struct dma_page, page_list);
291 if (is_page_busy(page)) {
292 if (pool->dev)
293 dev_err(pool->dev,
294 "dma_pool_destroy %s, %p busy\n",
295 pool->name, page->vaddr);
296 else
297 pr_err("dma_pool_destroy %s, %p busy\n",
298 pool->name, page->vaddr);
299 /* leak the still-in-use consistent memory */
300 list_del(&page->page_list);
301 kfree(page);
302 } else
303 pool_free_page(pool, page);
304 }
305
306 kfree(pool);
307}
308EXPORT_SYMBOL(dma_pool_destroy);
309
310/**
311 * dma_pool_alloc - get a block of consistent memory
312 * @pool: dma pool that will produce the block
313 * @mem_flags: GFP_* bitmask
314 * @handle: pointer to dma address of block
315 *
316 * This returns the kernel virtual address of a currently unused block,
317 * and reports its dma address through the handle.
318 * If such a memory block can't be allocated, %NULL is returned.
319 */
320void *dma_pool_alloc(struct dma_pool *pool, gfp_t mem_flags,
321 dma_addr_t *handle)
322{
323 unsigned long flags;
324 struct dma_page *page;
325 size_t offset;
326 void *retval;
327
328 might_sleep_if(gfpflags_allow_blocking(mem_flags));
329
330 spin_lock_irqsave(&pool->lock, flags);
331 list_for_each_entry(page, &pool->page_list, page_list) {
332 if (page->offset < pool->allocation)
333 goto ready;
334 }
335
336 /* pool_alloc_page() might sleep, so temporarily drop &pool->lock */
337 spin_unlock_irqrestore(&pool->lock, flags);
338
339 page = pool_alloc_page(pool, mem_flags & (~__GFP_ZERO));
340 if (!page)
341 return NULL;
342
343 spin_lock_irqsave(&pool->lock, flags);
344
345 list_add(&page->page_list, &pool->page_list);
346 ready:
347 page->in_use++;
348 offset = page->offset;
349 page->offset = *(int *)(page->vaddr + offset);
350 retval = offset + page->vaddr;
351 *handle = offset + page->dma;
352#ifdef DMAPOOL_DEBUG
353 {
354 int i;
355 u8 *data = retval;
356 /* page->offset is stored in first 4 bytes */
357 for (i = sizeof(page->offset); i < pool->size; i++) {
358 if (data[i] == POOL_POISON_FREED)
359 continue;
360 if (pool->dev)
361 dev_err(pool->dev,
362 "dma_pool_alloc %s, %p (corrupted)\n",
363 pool->name, retval);
364 else
365 pr_err("dma_pool_alloc %s, %p (corrupted)\n",
366 pool->name, retval);
367
368 /*
369 * Dump the first 4 bytes even if they are not
370 * POOL_POISON_FREED
371 */
372 print_hex_dump(KERN_ERR, "", DUMP_PREFIX_OFFSET, 16, 1,
373 data, pool->size, 1);
374 break;
375 }
376 }
377 if (!(mem_flags & __GFP_ZERO))
378 memset(retval, POOL_POISON_ALLOCATED, pool->size);
379#endif
380 spin_unlock_irqrestore(&pool->lock, flags);
381
382 if (mem_flags & __GFP_ZERO)
383 memset(retval, 0, pool->size);
384
385 return retval;
386}
387EXPORT_SYMBOL(dma_pool_alloc);
388
389static struct dma_page *pool_find_page(struct dma_pool *pool, dma_addr_t dma)
390{
391 struct dma_page *page;
392
393 list_for_each_entry(page, &pool->page_list, page_list) {
394 if (dma < page->dma)
395 continue;
396 if ((dma - page->dma) < pool->allocation)
397 return page;
398 }
399 return NULL;
400}
401
402/**
403 * dma_pool_free - put block back into dma pool
404 * @pool: the dma pool holding the block
405 * @vaddr: virtual address of block
406 * @dma: dma address of block
407 *
408 * Caller promises neither device nor driver will again touch this block
409 * unless it is first re-allocated.
410 */
411void dma_pool_free(struct dma_pool *pool, void *vaddr, dma_addr_t dma)
412{
413 struct dma_page *page;
414 unsigned long flags;
415 unsigned int offset;
416
417 spin_lock_irqsave(&pool->lock, flags);
418 page = pool_find_page(pool, dma);
419 if (!page) {
420 spin_unlock_irqrestore(&pool->lock, flags);
421 if (pool->dev)
422 dev_err(pool->dev,
423 "dma_pool_free %s, %p/%lx (bad dma)\n",
424 pool->name, vaddr, (unsigned long)dma);
425 else
426 pr_err("dma_pool_free %s, %p/%lx (bad dma)\n",
427 pool->name, vaddr, (unsigned long)dma);
428 return;
429 }
430
431 offset = vaddr - page->vaddr;
432#ifdef DMAPOOL_DEBUG
433 if ((dma - page->dma) != offset) {
434 spin_unlock_irqrestore(&pool->lock, flags);
435 if (pool->dev)
436 dev_err(pool->dev,
437 "dma_pool_free %s, %p (bad vaddr)/%Lx\n",
438 pool->name, vaddr, (unsigned long long)dma);
439 else
440 pr_err("dma_pool_free %s, %p (bad vaddr)/%Lx\n",
441 pool->name, vaddr, (unsigned long long)dma);
442 return;
443 }
444 {
445 unsigned int chain = page->offset;
446 while (chain < pool->allocation) {
447 if (chain != offset) {
448 chain = *(int *)(page->vaddr + chain);
449 continue;
450 }
451 spin_unlock_irqrestore(&pool->lock, flags);
452 if (pool->dev)
453 dev_err(pool->dev, "dma_pool_free %s, dma %Lx already free\n",
454 pool->name, (unsigned long long)dma);
455 else
456 pr_err("dma_pool_free %s, dma %Lx already free\n",
457 pool->name, (unsigned long long)dma);
458 return;
459 }
460 }
461 memset(vaddr, POOL_POISON_FREED, pool->size);
462#endif
463
464 page->in_use--;
465 *(int *)vaddr = page->offset;
466 page->offset = offset;
467 /*
468 * Resist a temptation to do
469 * if (!is_page_busy(page)) pool_free_page(pool, page);
470 * Better have a few empty pages hang around.
471 */
472 spin_unlock_irqrestore(&pool->lock, flags);
473}
474EXPORT_SYMBOL(dma_pool_free);
475
476/*
477 * Managed DMA pool
478 */
479static void dmam_pool_release(struct device *dev, void *res)
480{
481 struct dma_pool *pool = *(struct dma_pool **)res;
482
483 dma_pool_destroy(pool);
484}
485
486static int dmam_pool_match(struct device *dev, void *res, void *match_data)
487{
488 return *(struct dma_pool **)res == match_data;
489}
490
491/**
492 * dmam_pool_create - Managed dma_pool_create()
493 * @name: name of pool, for diagnostics
494 * @dev: device that will be doing the DMA
495 * @size: size of the blocks in this pool.
496 * @align: alignment requirement for blocks; must be a power of two
497 * @allocation: returned blocks won't cross this boundary (or zero)
498 *
499 * Managed dma_pool_create(). DMA pool created with this function is
500 * automatically destroyed on driver detach.
501 */
502struct dma_pool *dmam_pool_create(const char *name, struct device *dev,
503 size_t size, size_t align, size_t allocation)
504{
505 struct dma_pool **ptr, *pool;
506
507 ptr = devres_alloc(dmam_pool_release, sizeof(*ptr), GFP_KERNEL);
508 if (!ptr)
509 return NULL;
510
511 pool = *ptr = dma_pool_create(name, dev, size, align, allocation);
512 if (pool)
513 devres_add(dev, ptr);
514 else
515 devres_free(ptr);
516
517 return pool;
518}
519EXPORT_SYMBOL(dmam_pool_create);
520
521/**
522 * dmam_pool_destroy - Managed dma_pool_destroy()
523 * @pool: dma pool that will be destroyed
524 *
525 * Managed dma_pool_destroy().
526 */
527void dmam_pool_destroy(struct dma_pool *pool)
528{
529 struct device *dev = pool->dev;
530
531 WARN_ON(devres_release(dev, dmam_pool_release, dmam_pool_match, pool));
532}
533EXPORT_SYMBOL(dmam_pool_destroy);