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
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	char name[32];
60	struct list_head pools;
61};
62
63struct dma_page {		/* cacheable header for 'allocation' bytes */
64	struct list_head page_list;
65	void *vaddr;
66	dma_addr_t dma;
67};
68
69static DEFINE_MUTEX(pools_lock);
70static DEFINE_MUTEX(pools_reg_lock);
71
72static 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
92static DEVICE_ATTR_RO(pools);
93
94#ifdef DMAPOOL_DEBUG
95static 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
120static 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
133static 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
159static 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
164static void pool_check_block(struct dma_pool *pool, struct dma_block *block,
165			     gfp_t mem_flags)
166{
167}
168
169static 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
176static void pool_init_page(struct dma_pool *pool, struct dma_page *page)
177{
178}
179#endif
180
181static 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
192static 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 */
224struct 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}
298EXPORT_SYMBOL(dma_pool_create);
299
300static 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
334static 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 */
360void 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}
392EXPORT_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 */
404void *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}
439EXPORT_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 */
450void 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}
462EXPORT_SYMBOL(dma_pool_free);
463
464/*
465 * Managed DMA pool
466 */
467static 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
474static 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 */
493struct 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}
510EXPORT_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 */
518void 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}
524EXPORT_SYMBOL(dmam_pool_destroy);
525