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/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>
39
40 #if defined(CONFIG_DEBUG_SLAB) || defined(CONFIG_SLUB_DEBUG_ON)
41 #define DMAPOOL_DEBUG 1
42 #endif
43
44 struct dma_pool { /* the pool */
45 struct list_head page_list;
46 spinlock_t lock;
47 size_t size;
48 struct device *dev;
49 size_t allocation;
50 size_t boundary;
51 char name[32];
52 wait_queue_head_t waitq;
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 #define POOL_TIMEOUT_JIFFIES ((100 /* msec */ * HZ) / 1000)
65
66 static DEFINE_MUTEX(pools_lock);
67
68 static ssize_t
show_pools(struct device * dev,struct device_attribute * attr,char * buf)69 show_pools(struct device *dev, struct device_attribute *attr, char *buf)
70 {
71 unsigned temp;
72 unsigned size;
73 char *next;
74 struct dma_page *page;
75 struct dma_pool *pool;
76
77 next = buf;
78 size = PAGE_SIZE;
79
80 temp = scnprintf(next, size, "poolinfo - 0.1\n");
81 size -= temp;
82 next += temp;
83
84 mutex_lock(&pools_lock);
85 list_for_each_entry(pool, &dev->dma_pools, pools) {
86 unsigned pages = 0;
87 unsigned blocks = 0;
88
89 list_for_each_entry(page, &pool->page_list, page_list) {
90 pages++;
91 blocks += page->in_use;
92 }
93
94 /* per-pool info, no real statistics yet */
95 temp = scnprintf(next, size, "%-16s %4u %4Zu %4Zu %2u\n",
96 pool->name, blocks,
97 pages * (pool->allocation / pool->size),
98 pool->size, pages);
99 size -= temp;
100 next += temp;
101 }
102 mutex_unlock(&pools_lock);
103
104 return PAGE_SIZE - size;
105 }
106
107 static DEVICE_ATTR(pools, S_IRUGO, show_pools, NULL);
108
109 /**
110 * dma_pool_create - Creates a pool of consistent memory blocks, for dma.
111 * @name: name of pool, for diagnostics
112 * @dev: device that will be doing the DMA
113 * @size: size of the blocks in this pool.
114 * @align: alignment requirement for blocks; must be a power of two
115 * @boundary: returned blocks won't cross this power of two boundary
116 * Context: !in_interrupt()
117 *
118 * Returns a dma allocation pool with the requested characteristics, or
119 * null if one can't be created. 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 */
dma_pool_create(const char * name,struct device * dev,size_t size,size_t align,size_t boundary)130 struct dma_pool *dma_pool_create(const char *name, struct device *dev,
131 size_t size, size_t align, size_t boundary)
132 {
133 struct dma_pool *retval;
134 size_t allocation;
135
136 if (align == 0) {
137 align = 1;
138 } else if (align & (align - 1)) {
139 return NULL;
140 }
141
142 if (size == 0) {
143 return NULL;
144 } else if (size < 4) {
145 size = 4;
146 }
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
159 retval = kmalloc_node(sizeof(*retval), GFP_KERNEL, dev_to_node(dev));
160 if (!retval)
161 return retval;
162
163 strlcpy(retval->name, name, sizeof(retval->name));
164
165 retval->dev = dev;
166
167 INIT_LIST_HEAD(&retval->page_list);
168 spin_lock_init(&retval->lock);
169 retval->size = size;
170 retval->boundary = boundary;
171 retval->allocation = allocation;
172 init_waitqueue_head(&retval->waitq);
173
174 if (dev) {
175 int ret;
176
177 mutex_lock(&pools_lock);
178 if (list_empty(&dev->dma_pools))
179 ret = device_create_file(dev, &dev_attr_pools);
180 else
181 ret = 0;
182 /* note: not currently insisting "name" be unique */
183 if (!ret)
184 list_add(&retval->pools, &dev->dma_pools);
185 else {
186 kfree(retval);
187 retval = NULL;
188 }
189 mutex_unlock(&pools_lock);
190 } else
191 INIT_LIST_HEAD(&retval->pools);
192
193 return retval;
194 }
195 EXPORT_SYMBOL(dma_pool_create);
196
pool_initialise_page(struct dma_pool * pool,struct dma_page * page)197 static void pool_initialise_page(struct dma_pool *pool, struct dma_page *page)
198 {
199 unsigned int offset = 0;
200 unsigned int next_boundary = pool->boundary;
201
202 do {
203 unsigned int next = offset + pool->size;
204 if (unlikely((next + pool->size) >= next_boundary)) {
205 next = next_boundary;
206 next_boundary += pool->boundary;
207 }
208 *(int *)(page->vaddr + offset) = next;
209 offset = next;
210 } while (offset < pool->allocation);
211 }
212
pool_alloc_page(struct dma_pool * pool,gfp_t mem_flags)213 static struct dma_page *pool_alloc_page(struct dma_pool *pool, gfp_t mem_flags)
214 {
215 struct dma_page *page;
216
217 page = kmalloc(sizeof(*page), mem_flags);
218 if (!page)
219 return NULL;
220 page->vaddr = dma_alloc_coherent(pool->dev, pool->allocation,
221 &page->dma, mem_flags);
222 if (page->vaddr) {
223 #ifdef DMAPOOL_DEBUG
224 memset(page->vaddr, POOL_POISON_FREED, pool->allocation);
225 #endif
226 pool_initialise_page(pool, page);
227 list_add(&page->page_list, &pool->page_list);
228 page->in_use = 0;
229 page->offset = 0;
230 } else {
231 kfree(page);
232 page = NULL;
233 }
234 return page;
235 }
236
is_page_busy(struct dma_page * page)237 static inline int is_page_busy(struct dma_page *page)
238 {
239 return page->in_use != 0;
240 }
241
pool_free_page(struct dma_pool * pool,struct dma_page * page)242 static void pool_free_page(struct dma_pool *pool, struct dma_page *page)
243 {
244 dma_addr_t dma = page->dma;
245
246 #ifdef DMAPOOL_DEBUG
247 memset(page->vaddr, POOL_POISON_FREED, pool->allocation);
248 #endif
249 dma_free_coherent(pool->dev, pool->allocation, page->vaddr, dma);
250 list_del(&page->page_list);
251 kfree(page);
252 }
253
254 /**
255 * dma_pool_destroy - destroys a pool of dma memory blocks.
256 * @pool: dma pool that will be destroyed
257 * Context: !in_interrupt()
258 *
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.
261 */
dma_pool_destroy(struct dma_pool * pool)262 void dma_pool_destroy(struct dma_pool *pool)
263 {
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);
269
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)) {
275 if (pool->dev)
276 dev_err(pool->dev,
277 "dma_pool_destroy %s, %p busy\n",
278 pool->name, page->vaddr);
279 else
280 printk(KERN_ERR
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);
285 kfree(page);
286 } else
287 pool_free_page(pool, page);
288 }
289
290 kfree(pool);
291 }
292 EXPORT_SYMBOL(dma_pool_destroy);
293
294 /**
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
299 *
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.
303 */
dma_pool_alloc(struct dma_pool * pool,gfp_t mem_flags,dma_addr_t * handle)304 void *dma_pool_alloc(struct dma_pool *pool, gfp_t mem_flags,
305 dma_addr_t *handle)
306 {
307 unsigned long flags;
308 struct dma_page *page;
309 size_t offset;
310 void *retval;
311
312 spin_lock_irqsave(&pool->lock, flags);
313 restart:
314 list_for_each_entry(page, &pool->page_list, page_list) {
315 if (page->offset < pool->allocation)
316 goto ready;
317 }
318 page = pool_alloc_page(pool, GFP_ATOMIC);
319 if (!page) {
320 if (mem_flags & __GFP_WAIT) {
321 DECLARE_WAITQUEUE(wait, current);
322
323 __set_current_state(TASK_INTERRUPTIBLE);
324 __add_wait_queue(&pool->waitq, &wait);
325 spin_unlock_irqrestore(&pool->lock, flags);
326
327 schedule_timeout(POOL_TIMEOUT_JIFFIES);
328
329 spin_lock_irqsave(&pool->lock, flags);
330 __remove_wait_queue(&pool->waitq, &wait);
331 goto restart;
332 }
333 retval = NULL;
334 goto done;
335 }
336
337 ready:
338 page->in_use++;
339 offset = page->offset;
340 page->offset = *(int *)(page->vaddr + offset);
341 retval = offset + page->vaddr;
342 *handle = offset + page->dma;
343 #ifdef DMAPOOL_DEBUG
344 memset(retval, POOL_POISON_ALLOCATED, pool->size);
345 #endif
346 done:
347 spin_unlock_irqrestore(&pool->lock, flags);
348 return retval;
349 }
350 EXPORT_SYMBOL(dma_pool_alloc);
351
pool_find_page(struct dma_pool * pool,dma_addr_t dma)352 static struct dma_page *pool_find_page(struct dma_pool *pool, dma_addr_t dma)
353 {
354 unsigned long flags;
355 struct dma_page *page;
356
357 spin_lock_irqsave(&pool->lock, flags);
358 list_for_each_entry(page, &pool->page_list, page_list) {
359 if (dma < page->dma)
360 continue;
361 if (dma < (page->dma + pool->allocation))
362 goto done;
363 }
364 page = NULL;
365 done:
366 spin_unlock_irqrestore(&pool->lock, flags);
367 return page;
368 }
369
370 /**
371 * dma_pool_free - put block back into dma pool
372 * @pool: the dma pool holding the block
373 * @vaddr: virtual address of block
374 * @dma: dma address of block
375 *
376 * Caller promises neither device nor driver will again touch this block
377 * unless it is first re-allocated.
378 */
dma_pool_free(struct dma_pool * pool,void * vaddr,dma_addr_t dma)379 void dma_pool_free(struct dma_pool *pool, void *vaddr, dma_addr_t dma)
380 {
381 struct dma_page *page;
382 unsigned long flags;
383 unsigned int offset;
384
385 page = pool_find_page(pool, dma);
386 if (!page) {
387 if (pool->dev)
388 dev_err(pool->dev,
389 "dma_pool_free %s, %p/%lx (bad dma)\n",
390 pool->name, vaddr, (unsigned long)dma);
391 else
392 printk(KERN_ERR "dma_pool_free %s, %p/%lx (bad dma)\n",
393 pool->name, vaddr, (unsigned long)dma);
394 return;
395 }
396
397 offset = vaddr - page->vaddr;
398 #ifdef DMAPOOL_DEBUG
399 if ((dma - page->dma) != offset) {
400 if (pool->dev)
401 dev_err(pool->dev,
402 "dma_pool_free %s, %p (bad vaddr)/%Lx\n",
403 pool->name, vaddr, (unsigned long long)dma);
404 else
405 printk(KERN_ERR
406 "dma_pool_free %s, %p (bad vaddr)/%Lx\n",
407 pool->name, vaddr, (unsigned long long)dma);
408 return;
409 }
410 {
411 unsigned int chain = page->offset;
412 while (chain < pool->allocation) {
413 if (chain != offset) {
414 chain = *(int *)(page->vaddr + chain);
415 continue;
416 }
417 if (pool->dev)
418 dev_err(pool->dev, "dma_pool_free %s, dma %Lx "
419 "already free\n", pool->name,
420 (unsigned long long)dma);
421 else
422 printk(KERN_ERR "dma_pool_free %s, dma %Lx "
423 "already free\n", pool->name,
424 (unsigned long long)dma);
425 return;
426 }
427 }
428 memset(vaddr, POOL_POISON_FREED, pool->size);
429 #endif
430
431 spin_lock_irqsave(&pool->lock, flags);
432 page->in_use--;
433 *(int *)vaddr = page->offset;
434 page->offset = offset;
435 if (waitqueue_active(&pool->waitq))
436 wake_up_locked(&pool->waitq);
437 /*
438 * Resist a temptation to do
439 * if (!is_page_busy(page)) pool_free_page(pool, page);
440 * Better have a few empty pages hang around.
441 */
442 spin_unlock_irqrestore(&pool->lock, flags);
443 }
444 EXPORT_SYMBOL(dma_pool_free);
445
446 /*
447 * Managed DMA pool
448 */
dmam_pool_release(struct device * dev,void * res)449 static void dmam_pool_release(struct device *dev, void *res)
450 {
451 struct dma_pool *pool = *(struct dma_pool **)res;
452
453 dma_pool_destroy(pool);
454 }
455
dmam_pool_match(struct device * dev,void * res,void * match_data)456 static int dmam_pool_match(struct device *dev, void *res, void *match_data)
457 {
458 return *(struct dma_pool **)res == match_data;
459 }
460
461 /**
462 * dmam_pool_create - Managed dma_pool_create()
463 * @name: name of pool, for diagnostics
464 * @dev: device that will be doing the DMA
465 * @size: size of the blocks in this pool.
466 * @align: alignment requirement for blocks; must be a power of two
467 * @allocation: returned blocks won't cross this boundary (or zero)
468 *
469 * Managed dma_pool_create(). DMA pool created with this function is
470 * automatically destroyed on driver detach.
471 */
dmam_pool_create(const char * name,struct device * dev,size_t size,size_t align,size_t allocation)472 struct dma_pool *dmam_pool_create(const char *name, struct device *dev,
473 size_t size, size_t align, size_t allocation)
474 {
475 struct dma_pool **ptr, *pool;
476
477 ptr = devres_alloc(dmam_pool_release, sizeof(*ptr), GFP_KERNEL);
478 if (!ptr)
479 return NULL;
480
481 pool = *ptr = dma_pool_create(name, dev, size, align, allocation);
482 if (pool)
483 devres_add(dev, ptr);
484 else
485 devres_free(ptr);
486
487 return pool;
488 }
489 EXPORT_SYMBOL(dmam_pool_create);
490
491 /**
492 * dmam_pool_destroy - Managed dma_pool_destroy()
493 * @pool: dma pool that will be destroyed
494 *
495 * Managed dma_pool_destroy().
496 */
dmam_pool_destroy(struct dma_pool * pool)497 void dmam_pool_destroy(struct dma_pool *pool)
498 {
499 struct device *dev = pool->dev;
500
501 dma_pool_destroy(pool);
502 WARN_ON(devres_destroy(dev, dmam_pool_release, dmam_pool_match, pool));
503 }
504 EXPORT_SYMBOL(dmam_pool_destroy);
505