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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 <[email protected]>
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
43struct dma_block {
44 struct dma_block *next_block;
45 dma_addr_t dma;
46};
47
48struct 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 int node;
60 char name[32];
61 struct list_head pools;
62};
63
64struct dma_page { /* cacheable header for 'allocation' bytes */
65 struct list_head page_list;
66 void *vaddr;
67 dma_addr_t dma;
68};
69
70static DEFINE_MUTEX(pools_lock);
71static DEFINE_MUTEX(pools_reg_lock);
72
73static ssize_t pools_show(struct device *dev, struct device_attribute *attr, char *buf)
74{
75 struct dma_pool *pool;
76 unsigned size;
77
78 size = sysfs_emit(buf, "poolinfo - 0.1\n");
79
80 mutex_lock(&pools_lock);
81 list_for_each_entry(pool, &dev->dma_pools, pools) {
82 /* per-pool info, no real statistics yet */
83 size += sysfs_emit_at(buf, size, "%-16s %4zu %4zu %4u %2zu\n",
84 pool->name, pool->nr_active,
85 pool->nr_blocks, pool->size,
86 pool->nr_pages);
87 }
88 mutex_unlock(&pools_lock);
89
90 return size;
91}
92
93static DEVICE_ATTR_RO(pools);
94
95#ifdef DMAPOOL_DEBUG
96static void pool_check_block(struct dma_pool *pool, struct dma_block *block,
97 gfp_t mem_flags)
98{
99 u8 *data = (void *)block;
100 int i;
101
102 for (i = sizeof(struct dma_block); i < pool->size; i++) {
103 if (data[i] == POOL_POISON_FREED)
104 continue;
105 dev_err(pool->dev, "%s %s, %p (corrupted)\n", __func__,
106 pool->name, block);
107
108 /*
109 * Dump the first 4 bytes even if they are not
110 * POOL_POISON_FREED
111 */
112 print_hex_dump(KERN_ERR, "", DUMP_PREFIX_OFFSET, 16, 1,
113 data, pool->size, 1);
114 break;
115 }
116
117 if (!want_init_on_alloc(mem_flags))
118 memset(block, POOL_POISON_ALLOCATED, pool->size);
119}
120
121static struct dma_page *pool_find_page(struct dma_pool *pool, dma_addr_t dma)
122{
123 struct dma_page *page;
124
125 list_for_each_entry(page, &pool->page_list, page_list) {
126 if (dma < page->dma)
127 continue;
128 if ((dma - page->dma) < pool->allocation)
129 return page;
130 }
131 return NULL;
132}
133
134static bool pool_block_err(struct dma_pool *pool, void *vaddr, dma_addr_t dma)
135{
136 struct dma_block *block = pool->next_block;
137 struct dma_page *page;
138
139 page = pool_find_page(pool, dma);
140 if (!page) {
141 dev_err(pool->dev, "%s %s, %p/%pad (bad dma)\n",
142 __func__, pool->name, vaddr, &dma);
143 return true;
144 }
145
146 while (block) {
147 if (block != vaddr) {
148 block = block->next_block;
149 continue;
150 }
151 dev_err(pool->dev, "%s %s, dma %pad already free\n",
152 __func__, pool->name, &dma);
153 return true;
154 }
155
156 memset(vaddr, POOL_POISON_FREED, pool->size);
157 return false;
158}
159
160static void pool_init_page(struct dma_pool *pool, struct dma_page *page)
161{
162 memset(page->vaddr, POOL_POISON_FREED, pool->allocation);
163}
164#else
165static void pool_check_block(struct dma_pool *pool, struct dma_block *block,
166 gfp_t mem_flags)
167{
168}
169
170static bool pool_block_err(struct dma_pool *pool, void *vaddr, dma_addr_t dma)
171{
172 if (want_init_on_free())
173 memset(vaddr, 0, pool->size);
174 return false;
175}
176
177static void pool_init_page(struct dma_pool *pool, struct dma_page *page)
178{
179}
180#endif
181
182static struct dma_block *pool_block_pop(struct dma_pool *pool)
183{
184 struct dma_block *block = pool->next_block;
185
186 if (block) {
187 pool->next_block = block->next_block;
188 pool->nr_active++;
189 }
190 return block;
191}
192
193static void pool_block_push(struct dma_pool *pool, struct dma_block *block,
194 dma_addr_t dma)
195{
196 block->dma = dma;
197 block->next_block = pool->next_block;
198 pool->next_block = block;
199}
200
201
202/**
203 * dma_pool_create_node - Creates a pool of coherent DMA memory blocks.
204 * @name: name of pool, for diagnostics
205 * @dev: device that will be doing the DMA
206 * @size: size of the blocks in this pool.
207 * @align: alignment requirement for blocks; must be a power of two
208 * @boundary: returned blocks won't cross this power of two boundary
209 * @node: optional NUMA node to allocate structs 'dma_pool' and 'dma_page' on
210 * Context: not in_interrupt()
211 *
212 * Given one of these pools, dma_pool_alloc()
213 * may be used to allocate memory. Such memory will all have coherent
214 * DMA mappings, accessible by the device and its driver without using
215 * cache flushing primitives. The actual size of blocks allocated may be
216 * larger than requested because of alignment.
217 *
218 * If @boundary is nonzero, objects returned from dma_pool_alloc() won't
219 * cross that size boundary. This is useful for devices which have
220 * addressing restrictions on individual DMA transfers, such as not crossing
221 * boundaries of 4KBytes.
222 *
223 * Return: a dma allocation pool with the requested characteristics, or
224 * %NULL if one can't be created.
225 */
226struct dma_pool *dma_pool_create_node(const char *name, struct device *dev,
227 size_t size, size_t align, size_t boundary, int node)
228{
229 struct dma_pool *retval;
230 size_t allocation;
231 bool empty;
232
233 if (!dev)
234 return NULL;
235
236 if (align == 0)
237 align = 1;
238 else if (align & (align - 1))
239 return NULL;
240
241 if (size == 0 || size > INT_MAX)
242 return NULL;
243 if (size < sizeof(struct dma_block))
244 size = sizeof(struct dma_block);
245
246 size = ALIGN(size, align);
247 allocation = max_t(size_t, size, PAGE_SIZE);
248
249 if (!boundary)
250 boundary = allocation;
251 else if ((boundary < size) || (boundary & (boundary - 1)))
252 return NULL;
253
254 boundary = min(boundary, allocation);
255
256 retval = kzalloc_node(sizeof(*retval), GFP_KERNEL, node);
257 if (!retval)
258 return retval;
259
260 strscpy(retval->name, name, sizeof(retval->name));
261
262 retval->dev = dev;
263
264 INIT_LIST_HEAD(&retval->page_list);
265 spin_lock_init(&retval->lock);
266 retval->size = size;
267 retval->boundary = boundary;
268 retval->allocation = allocation;
269 retval->node = node;
270 INIT_LIST_HEAD(&retval->pools);
271
272 /*
273 * pools_lock ensures that the ->dma_pools list does not get corrupted.
274 * pools_reg_lock ensures that there is not a race between
275 * dma_pool_create() and dma_pool_destroy() or within dma_pool_create()
276 * when the first invocation of dma_pool_create() failed on
277 * device_create_file() and the second assumes that it has been done (I
278 * know it is a short window).
279 */
280 mutex_lock(&pools_reg_lock);
281 mutex_lock(&pools_lock);
282 empty = list_empty(&dev->dma_pools);
283 list_add(&retval->pools, &dev->dma_pools);
284 mutex_unlock(&pools_lock);
285 if (empty) {
286 int err;
287
288 err = device_create_file(dev, &dev_attr_pools);
289 if (err) {
290 mutex_lock(&pools_lock);
291 list_del(&retval->pools);
292 mutex_unlock(&pools_lock);
293 mutex_unlock(&pools_reg_lock);
294 kfree(retval);
295 return NULL;
296 }
297 }
298 mutex_unlock(&pools_reg_lock);
299 return retval;
300}
301EXPORT_SYMBOL(dma_pool_create_node);
302
303static void pool_initialise_page(struct dma_pool *pool, struct dma_page *page)
304{
305 unsigned int next_boundary = pool->boundary, offset = 0;
306 struct dma_block *block, *first = NULL, *last = NULL;
307
308 pool_init_page(pool, page);
309 while (offset + pool->size <= pool->allocation) {
310 if (offset + pool->size > next_boundary) {
311 offset = next_boundary;
312 next_boundary += pool->boundary;
313 continue;
314 }
315
316 block = page->vaddr + offset;
317 block->dma = page->dma + offset;
318 block->next_block = NULL;
319
320 if (last)
321 last->next_block = block;
322 else
323 first = block;
324 last = block;
325
326 offset += pool->size;
327 pool->nr_blocks++;
328 }
329
330 last->next_block = pool->next_block;
331 pool->next_block = first;
332
333 list_add(&page->page_list, &pool->page_list);
334 pool->nr_pages++;
335}
336
337static struct dma_page *pool_alloc_page(struct dma_pool *pool, gfp_t mem_flags)
338{
339 struct dma_page *page;
340
341 page = kmalloc_node(sizeof(*page), mem_flags, pool->node);
342 if (!page)
343 return NULL;
344
345 page->vaddr = dma_alloc_coherent(pool->dev, pool->allocation,
346 &page->dma, mem_flags);
347 if (!page->vaddr) {
348 kfree(page);
349 return NULL;
350 }
351
352 return page;
353}
354
355/**
356 * dma_pool_destroy - destroys a pool of dma memory blocks.
357 * @pool: dma pool that will be destroyed
358 * Context: !in_interrupt()
359 *
360 * Caller guarantees that no more memory from the pool is in use,
361 * and that nothing will try to use the pool after this call.
362 */
363void dma_pool_destroy(struct dma_pool *pool)
364{
365 struct dma_page *page, *tmp;
366 bool empty, busy = false;
367
368 if (unlikely(!pool))
369 return;
370
371 mutex_lock(&pools_reg_lock);
372 mutex_lock(&pools_lock);
373 list_del(&pool->pools);
374 empty = list_empty(&pool->dev->dma_pools);
375 mutex_unlock(&pools_lock);
376 if (empty)
377 device_remove_file(pool->dev, &dev_attr_pools);
378 mutex_unlock(&pools_reg_lock);
379
380 if (pool->nr_active) {
381 dev_err(pool->dev, "%s %s busy\n", __func__, pool->name);
382 busy = true;
383 }
384
385 list_for_each_entry_safe(page, tmp, &pool->page_list, page_list) {
386 if (!busy)
387 dma_free_coherent(pool->dev, pool->allocation,
388 page->vaddr, page->dma);
389 list_del(&page->page_list);
390 kfree(page);
391 }
392
393 kfree(pool);
394}
395EXPORT_SYMBOL(dma_pool_destroy);
396
397/**
398 * dma_pool_alloc - get a block of coherent memory
399 * @pool: dma pool that will produce the block
400 * @mem_flags: GFP_* bitmask
401 * @handle: pointer to dma address of block
402 *
403 * Return: the kernel virtual address of a currently unused block,
404 * and reports its dma address through the handle.
405 * If such a memory block can't be allocated, %NULL is returned.
406 */
407void *dma_pool_alloc(struct dma_pool *pool, gfp_t mem_flags,
408 dma_addr_t *handle)
409{
410 struct dma_block *block;
411 struct dma_page *page;
412 unsigned long flags;
413
414 might_alloc(mem_flags);
415
416 spin_lock_irqsave(&pool->lock, flags);
417 block = pool_block_pop(pool);
418 if (!block) {
419 /*
420 * pool_alloc_page() might sleep, so temporarily drop
421 * &pool->lock
422 */
423 spin_unlock_irqrestore(&pool->lock, flags);
424
425 page = pool_alloc_page(pool, mem_flags & (~__GFP_ZERO));
426 if (!page)
427 return NULL;
428
429 spin_lock_irqsave(&pool->lock, flags);
430 pool_initialise_page(pool, page);
431 block = pool_block_pop(pool);
432 }
433 spin_unlock_irqrestore(&pool->lock, flags);
434
435 *handle = block->dma;
436 pool_check_block(pool, block, mem_flags);
437 if (want_init_on_alloc(mem_flags))
438 memset(block, 0, pool->size);
439
440 return block;
441}
442EXPORT_SYMBOL(dma_pool_alloc);
443
444/**
445 * dma_pool_free - put block back into dma pool
446 * @pool: the dma pool holding the block
447 * @vaddr: virtual address of block
448 * @dma: dma address of block
449 *
450 * Caller promises neither device nor driver will again touch this block
451 * unless it is first re-allocated.
452 */
453void dma_pool_free(struct dma_pool *pool, void *vaddr, dma_addr_t dma)
454{
455 struct dma_block *block = vaddr;
456 unsigned long flags;
457
458 spin_lock_irqsave(&pool->lock, flags);
459 if (!pool_block_err(pool, vaddr, dma)) {
460 pool_block_push(pool, block, dma);
461 pool->nr_active--;
462 }
463 spin_unlock_irqrestore(&pool->lock, flags);
464}
465EXPORT_SYMBOL(dma_pool_free);
466
467/*
468 * Managed DMA pool
469 */
470static void dmam_pool_release(struct device *dev, void *res)
471{
472 struct dma_pool *pool = *(struct dma_pool **)res;
473
474 dma_pool_destroy(pool);
475}
476
477static int dmam_pool_match(struct device *dev, void *res, void *match_data)
478{
479 return *(struct dma_pool **)res == match_data;
480}
481
482/**
483 * dmam_pool_create - Managed dma_pool_create()
484 * @name: name of pool, for diagnostics
485 * @dev: device that will be doing the DMA
486 * @size: size of the blocks in this pool.
487 * @align: alignment requirement for blocks; must be a power of two
488 * @allocation: returned blocks won't cross this boundary (or zero)
489 *
490 * Managed dma_pool_create(). DMA pool created with this function is
491 * automatically destroyed on driver detach.
492 *
493 * Return: a managed dma allocation pool with the requested
494 * characteristics, or %NULL if one can't be created.
495 */
496struct dma_pool *dmam_pool_create(const char *name, struct device *dev,
497 size_t size, size_t align, size_t allocation)
498{
499 struct dma_pool **ptr, *pool;
500
501 ptr = devres_alloc(dmam_pool_release, sizeof(*ptr), GFP_KERNEL);
502 if (!ptr)
503 return NULL;
504
505 pool = *ptr = dma_pool_create(name, dev, size, align, allocation);
506 if (pool)
507 devres_add(dev, ptr);
508 else
509 devres_free(ptr);
510
511 return pool;
512}
513EXPORT_SYMBOL(dmam_pool_create);
514
515/**
516 * dmam_pool_destroy - Managed dma_pool_destroy()
517 * @pool: dma pool that will be destroyed
518 *
519 * Managed dma_pool_destroy().
520 */
521void dmam_pool_destroy(struct dma_pool *pool)
522{
523 struct device *dev = pool->dev;
524
525 WARN_ON(devres_release(dev, dmam_pool_release, dmam_pool_match, pool));
526}
527EXPORT_SYMBOL(dmam_pool_destroy);