1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * DMA Pool allocator
4 *
5 * Copyright 2001 David Brownell
6 * Copyright 2007 Intel Corporation
7 * Author: Matthew Wilcox <willy@linux.intel.com>
8 *
9 * This allocator returns small blocks of a given size which are DMA-able by
10 * the given device. It uses the dma_alloc_coherent page allocator to get
11 * new pages, then splits them up into blocks of the required size.
12 * Many older drivers still have their own code to do this.
13 *
14 * The current design of this allocator is fairly simple. The pool is
15 * represented by the 'struct dma_pool' which keeps a doubly-linked list of
16 * allocated pages. Each page in the page_list is split into blocks of at
17 * least 'size' bytes. Free blocks are tracked in an unsorted singly-linked
18 * list of free blocks across all pages. Used blocks aren't tracked, but we
19 * keep a count of how many are currently allocated from each page.
20 */
21
22 #include <linux/device.h>
23 #include <linux/dma-mapping.h>
24 #include <linux/dmapool.h>
25 #include <linux/kernel.h>
26 #include <linux/list.h>
27 #include <linux/export.h>
28 #include <linux/mutex.h>
29 #include <linux/poison.h>
30 #include <linux/sched.h>
31 #include <linux/sched/mm.h>
32 #include <linux/slab.h>
33 #include <linux/stat.h>
34 #include <linux/spinlock.h>
35 #include <linux/string.h>
36 #include <linux/types.h>
37 #include <linux/wait.h>
38
39 #ifdef CONFIG_SLUB_DEBUG_ON
40 #define DMAPOOL_DEBUG 1
41 #endif
42
43 struct dma_block {
44 struct dma_block *next_block;
45 dma_addr_t dma;
46 };
47
48 struct dma_pool { /* the pool */
49 struct list_head page_list;
50 spinlock_t lock;
51 struct dma_block *next_block;
52 size_t nr_blocks;
53 size_t nr_active;
54 size_t nr_pages;
55 struct device *dev;
56 unsigned int size;
57 unsigned int allocation;
58 unsigned int boundary;
59 char name[32];
60 struct list_head pools;
61 };
62
63 struct dma_page { /* cacheable header for 'allocation' bytes */
64 struct list_head page_list;
65 void *vaddr;
66 dma_addr_t dma;
67 };
68
69 static DEFINE_MUTEX(pools_lock);
70 static DEFINE_MUTEX(pools_reg_lock);
71
72 static ssize_t pools_show(struct device *dev, struct device_attribute *attr, char *buf)
73 {
74 struct dma_pool *pool;
75 unsigned size;
76
77 size = sysfs_emit(buf, "poolinfo - 0.1\n");
78
79 mutex_lock(&pools_lock);
80 list_for_each_entry(pool, &dev->dma_pools, pools) {
81 /* per-pool info, no real statistics yet */
82 size += sysfs_emit_at(buf, size, "%-16s %4zu %4zu %4u %2zu\n",
83 pool->name, pool->nr_active,
84 pool->nr_blocks, pool->size,
85 pool->nr_pages);
86 }
87 mutex_unlock(&pools_lock);
88
89 return size;
90 }
91
92 static DEVICE_ATTR_RO(pools);
93
94 #ifdef DMAPOOL_DEBUG
95 static void pool_check_block(struct dma_pool *pool, struct dma_block *block,
96 gfp_t mem_flags)
97 {
98 u8 *data = (void *)block;
99 int i;
100
101 for (i = sizeof(struct dma_block); i < pool->size; i++) {
102 if (data[i] == POOL_POISON_FREED)
103 continue;
104 dev_err(pool->dev, "%s %s, %p (corrupted)\n", __func__,
105 pool->name, block);
106
107 /*
108 * Dump the first 4 bytes even if they are not
109 * POOL_POISON_FREED
110 */
111 print_hex_dump(KERN_ERR, "", DUMP_PREFIX_OFFSET, 16, 1,
112 data, pool->size, 1);
113 break;
114 }
115
116 if (!want_init_on_alloc(mem_flags))
117 memset(block, POOL_POISON_ALLOCATED, pool->size);
118 }
119
120 static struct dma_page *pool_find_page(struct dma_pool *pool, dma_addr_t dma)
121 {
122 struct dma_page *page;
123
124 list_for_each_entry(page, &pool->page_list, page_list) {
125 if (dma < page->dma)
126 continue;
127 if ((dma - page->dma) < pool->allocation)
128 return page;
129 }
130 return NULL;
131 }
132
133 static bool pool_block_err(struct dma_pool *pool, void *vaddr, dma_addr_t dma)
134 {
135 struct dma_block *block = pool->next_block;
136 struct dma_page *page;
137
138 page = pool_find_page(pool, dma);
139 if (!page) {
140 dev_err(pool->dev, "%s %s, %p/%pad (bad dma)\n",
141 __func__, pool->name, vaddr, &dma);
142 return true;
143 }
144
145 while (block) {
146 if (block != vaddr) {
147 block = block->next_block;
148 continue;
149 }
150 dev_err(pool->dev, "%s %s, dma %pad already free\n",
151 __func__, pool->name, &dma);
152 return true;
153 }
154
155 memset(vaddr, POOL_POISON_FREED, pool->size);
156 return false;
157 }
158
159 static void pool_init_page(struct dma_pool *pool, struct dma_page *page)
160 {
161 memset(page->vaddr, POOL_POISON_FREED, pool->allocation);
162 }
163 #else
164 static void pool_check_block(struct dma_pool *pool, struct dma_block *block,
165 gfp_t mem_flags)
166 {
167 }
168
169 static bool pool_block_err(struct dma_pool *pool, void *vaddr, dma_addr_t dma)
170 {
171 if (want_init_on_free())
172 memset(vaddr, 0, pool->size);
173 return false;
174 }
175
176 static void pool_init_page(struct dma_pool *pool, struct dma_page *page)
177 {
178 }
179 #endif
180
181 static struct dma_block *pool_block_pop(struct dma_pool *pool)
182 {
183 struct dma_block *block = pool->next_block;
184
185 if (block) {
186 pool->next_block = block->next_block;
187 pool->nr_active++;
188 }
189 return block;
190 }
191
192 static void pool_block_push(struct dma_pool *pool, struct dma_block *block,
193 dma_addr_t dma)
194 {
195 block->dma = dma;
196 block->next_block = pool->next_block;
197 pool->next_block = block;
198 }
199
200
201 /**
202 * dma_pool_create - Creates a pool of consistent memory blocks, for dma.
203 * @name: name of pool, for diagnostics
204 * @dev: device that will be doing the DMA
205 * @size: size of the blocks in this pool.
206 * @align: alignment requirement for blocks; must be a power of two
207 * @boundary: returned blocks won't cross this power of two boundary
208 * Context: not in_interrupt()
209 *
210 * Given one of these pools, dma_pool_alloc()
211 * may be used to allocate memory. Such memory will all have "consistent"
212 * DMA mappings, accessible by the device and its driver without using
213 * cache flushing primitives. The actual size of blocks allocated may be
214 * larger than requested because of alignment.
215 *
216 * If @boundary is nonzero, objects returned from dma_pool_alloc() won't
217 * cross that size boundary. This is useful for devices which have
218 * addressing restrictions on individual DMA transfers, such as not crossing
219 * boundaries of 4KBytes.
220 *
221 * Return: a dma allocation pool with the requested characteristics, or
222 * %NULL if one can't be created.
223 */
224 struct dma_pool *dma_pool_create(const char *name, struct device *dev,
225 size_t size, size_t align, size_t boundary)
226 {
227 struct dma_pool *retval;
228 size_t allocation;
229 bool empty;
230
231 if (!dev)
232 return NULL;
233
234 if (align == 0)
235 align = 1;
236 else if (align & (align - 1))
237 return NULL;
238
239 if (size == 0 || size > INT_MAX)
240 return NULL;
241 if (size < sizeof(struct dma_block))
242 size = sizeof(struct dma_block);
243
244 size = ALIGN(size, align);
245 allocation = max_t(size_t, size, PAGE_SIZE);
246
247 if (!boundary)
248 boundary = allocation;
249 else if ((boundary < size) || (boundary & (boundary - 1)))
250 return NULL;
251
252 boundary = min(boundary, allocation);
253
254 retval = kzalloc(sizeof(*retval), GFP_KERNEL);
255 if (!retval)
256 return retval;
257
258 strscpy(retval->name, name, sizeof(retval->name));
259
260 retval->dev = dev;
261
262 INIT_LIST_HEAD(&retval->page_list);
263 spin_lock_init(&retval->lock);
264 retval->size = size;
265 retval->boundary = boundary;
266 retval->allocation = allocation;
267 INIT_LIST_HEAD(&retval->pools);
268
269 /*
270 * pools_lock ensures that the ->dma_pools list does not get corrupted.
271 * pools_reg_lock ensures that there is not a race between
272 * dma_pool_create() and dma_pool_destroy() or within dma_pool_create()
273 * when the first invocation of dma_pool_create() failed on
274 * device_create_file() and the second assumes that it has been done (I
275 * know it is a short window).
276 */
277 mutex_lock(&pools_reg_lock);
278 mutex_lock(&pools_lock);
279 empty = list_empty(&dev->dma_pools);
280 list_add(&retval->pools, &dev->dma_pools);
281 mutex_unlock(&pools_lock);
282 if (empty) {
283 int err;
284
285 err = device_create_file(dev, &dev_attr_pools);
286 if (err) {
287 mutex_lock(&pools_lock);
288 list_del(&retval->pools);
289 mutex_unlock(&pools_lock);
290 mutex_unlock(&pools_reg_lock);
291 kfree(retval);
292 return NULL;
293 }
294 }
295 mutex_unlock(&pools_reg_lock);
296 return retval;
297 }
298 EXPORT_SYMBOL(dma_pool_create);
299
300 static void pool_initialise_page(struct dma_pool *pool, struct dma_page *page)
301 {
302 unsigned int next_boundary = pool->boundary, offset = 0;
303 struct dma_block *block, *first = NULL, *last = NULL;
304
305 pool_init_page(pool, page);
306 while (offset + pool->size <= pool->allocation) {
307 if (offset + pool->size > next_boundary) {
308 offset = next_boundary;
309 next_boundary += pool->boundary;
310 continue;
311 }
312
313 block = page->vaddr + offset;
314 block->dma = page->dma + offset;
315 block->next_block = NULL;
316
317 if (last)
318 last->next_block = block;
319 else
320 first = block;
321 last = block;
322
323 offset += pool->size;
324 pool->nr_blocks++;
325 }
326
327 last->next_block = pool->next_block;
328 pool->next_block = first;
329
330 list_add(&page->page_list, &pool->page_list);
331 pool->nr_pages++;
332 }
333
334 static struct dma_page *pool_alloc_page(struct dma_pool *pool, gfp_t mem_flags)
335 {
336 struct dma_page *page;
337
338 page = kmalloc(sizeof(*page), mem_flags);
339 if (!page)
340 return NULL;
341
342 page->vaddr = dma_alloc_coherent(pool->dev, pool->allocation,
343 &page->dma, mem_flags);
344 if (!page->vaddr) {
345 kfree(page);
346 return NULL;
347 }
348
349 return page;
350 }
351
352 /**
353 * dma_pool_destroy - destroys a pool of dma memory blocks.
354 * @pool: dma pool that will be destroyed
355 * Context: !in_interrupt()
356 *
357 * Caller guarantees that no more memory from the pool is in use,
358 * and that nothing will try to use the pool after this call.
359 */
360 void dma_pool_destroy(struct dma_pool *pool)
361 {
362 struct dma_page *page, *tmp;
363 bool empty, busy = false;
364
365 if (unlikely(!pool))
366 return;
367
368 mutex_lock(&pools_reg_lock);
369 mutex_lock(&pools_lock);
370 list_del(&pool->pools);
371 empty = list_empty(&pool->dev->dma_pools);
372 mutex_unlock(&pools_lock);
373 if (empty)
374 device_remove_file(pool->dev, &dev_attr_pools);
375 mutex_unlock(&pools_reg_lock);
376
377 if (pool->nr_active) {
378 dev_err(pool->dev, "%s %s busy\n", __func__, pool->name);
379 busy = true;
380 }
381
382 list_for_each_entry_safe(page, tmp, &pool->page_list, page_list) {
383 if (!busy)
384 dma_free_coherent(pool->dev, pool->allocation,
385 page->vaddr, page->dma);
386 list_del(&page->page_list);
387 kfree(page);
388 }
389
390 kfree(pool);
391 }
392 EXPORT_SYMBOL(dma_pool_destroy);
393
394 /**
395 * dma_pool_alloc - get a block of consistent memory
396 * @pool: dma pool that will produce the block
397 * @mem_flags: GFP_* bitmask
398 * @handle: pointer to dma address of block
399 *
400 * Return: the kernel virtual address of a currently unused block,
401 * and reports its dma address through the handle.
402 * If such a memory block can't be allocated, %NULL is returned.
403 */
404 void *dma_pool_alloc(struct dma_pool *pool, gfp_t mem_flags,
405 dma_addr_t *handle)
406 {
407 struct dma_block *block;
408 struct dma_page *page;
409 unsigned long flags;
410
411 might_alloc(mem_flags);
412
413 spin_lock_irqsave(&pool->lock, flags);
414 block = pool_block_pop(pool);
415 if (!block) {
416 /*
417 * pool_alloc_page() might sleep, so temporarily drop
418 * &pool->lock
419 */
420 spin_unlock_irqrestore(&pool->lock, flags);
421
422 page = pool_alloc_page(pool, mem_flags & (~__GFP_ZERO));
423 if (!page)
424 return NULL;
425
426 spin_lock_irqsave(&pool->lock, flags);
427 pool_initialise_page(pool, page);
428 block = pool_block_pop(pool);
429 }
430 spin_unlock_irqrestore(&pool->lock, flags);
431
432 *handle = block->dma;
433 pool_check_block(pool, block, mem_flags);
434 if (want_init_on_alloc(mem_flags))
435 memset(block, 0, pool->size);
436
437 return block;
438 }
439 EXPORT_SYMBOL(dma_pool_alloc);
440
441 /**
442 * dma_pool_free - put block back into dma pool
443 * @pool: the dma pool holding the block
444 * @vaddr: virtual address of block
445 * @dma: dma address of block
446 *
447 * Caller promises neither device nor driver will again touch this block
448 * unless it is first re-allocated.
449 */
450 void dma_pool_free(struct dma_pool *pool, void *vaddr, dma_addr_t dma)
451 {
452 struct dma_block *block = vaddr;
453 unsigned long flags;
454
455 spin_lock_irqsave(&pool->lock, flags);
456 if (!pool_block_err(pool, vaddr, dma)) {
457 pool_block_push(pool, block, dma);
458 pool->nr_active--;
459 }
460 spin_unlock_irqrestore(&pool->lock, flags);
461 }
462 EXPORT_SYMBOL(dma_pool_free);
463
464 /*
465 * Managed DMA pool
466 */
467 static void dmam_pool_release(struct device *dev, void *res)
468 {
469 struct dma_pool *pool = *(struct dma_pool **)res;
470
471 dma_pool_destroy(pool);
472 }
473
474 static int dmam_pool_match(struct device *dev, void *res, void *match_data)
475 {
476 return *(struct dma_pool **)res == match_data;
477 }
478
479 /**
480 * dmam_pool_create - Managed dma_pool_create()
481 * @name: name of pool, for diagnostics
482 * @dev: device that will be doing the DMA
483 * @size: size of the blocks in this pool.
484 * @align: alignment requirement for blocks; must be a power of two
485 * @allocation: returned blocks won't cross this boundary (or zero)
486 *
487 * Managed dma_pool_create(). DMA pool created with this function is
488 * automatically destroyed on driver detach.
489 *
490 * Return: a managed dma allocation pool with the requested
491 * characteristics, or %NULL if one can't be created.
492 */
493 struct dma_pool *dmam_pool_create(const char *name, struct device *dev,
494 size_t size, size_t align, size_t allocation)
495 {
496 struct dma_pool **ptr, *pool;
497
498 ptr = devres_alloc(dmam_pool_release, sizeof(*ptr), GFP_KERNEL);
499 if (!ptr)
500 return NULL;
501
502 pool = *ptr = dma_pool_create(name, dev, size, align, allocation);
503 if (pool)
504 devres_add(dev, ptr);
505 else
506 devres_free(ptr);
507
508 return pool;
509 }
510 EXPORT_SYMBOL(dmam_pool_create);
511
512 /**
513 * dmam_pool_destroy - Managed dma_pool_destroy()
514 * @pool: dma pool that will be destroyed
515 *
516 * Managed dma_pool_destroy().
517 */
518 void dmam_pool_destroy(struct dma_pool *pool)
519 {
520 struct device *dev = pool->dev;
521
522 WARN_ON(devres_release(dev, dmam_pool_release, dmam_pool_match, pool));
523 }
524 EXPORT_SYMBOL(dmam_pool_destroy);
525
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