aboutsummaryrefslogtreecommitdiffstats
path: root/drivers/base/dmapool.c
blob: b2efbd4cf710d9d0ce79474c2280d04c6bbd7c42 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422

#include <linux/device.h>
#include <linux/mm.h>
#include <asm/io.h>		/* Needed for i386 to build */
#include <asm/scatterlist.h>	/* Needed for i386 to build */
#include <linux/dma-mapping.h>
#include <linux/dmapool.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/poison.h>

/*
 * Pool allocator ... wraps the dma_alloc_coherent page allocator, so
 * small blocks are easily used by drivers for bus mastering controllers.
 * This should probably be sharing the guts of the slab allocator.
 */

struct dma_pool {	/* the pool */
	struct list_head	page_list;
	spinlock_t		lock;
	size_t			blocks_per_page;
	size_t			size;
	struct device		*dev;
	size_t			allocation;
	char			name [32];
	wait_queue_head_t	waitq;
	struct list_head	pools;
};

struct dma_page {	/* cacheable header for 'allocation' bytes */
	struct list_head	page_list;
	void			*vaddr;
	dma_addr_t		dma;
	unsigned		in_use;
	unsigned long		bitmap [0];
};

#define	POOL_TIMEOUT_JIFFIES	((100 /* msec */ * HZ) / 1000)

static DECLARE_MUTEX (pools_lock);

static ssize_t
show_pools (struct device *dev, struct device_attribute *attr, char *buf)
{
	unsigned temp;
	unsigned size;
	char *next;
	struct dma_page *page;
	struct dma_pool *pool;

	next = buf;
	size = PAGE_SIZE;

	temp = scnprintf(next, size, "poolinfo - 0.1\n");
	size -= temp;
	next += temp;

	down (&pools_lock);
	list_for_each_entry(pool, &dev->dma_pools, pools) {
		unsigned pages = 0;
		unsigned blocks = 0;

		list_for_each_entry(page, &pool->page_list, page_list) {
			pages++;
			blocks += page->in_use;
		}

		/* per-pool info, no real statistics yet */
		temp = scnprintf(next, size, "%-16s %4u %4Zu %4Zu %2u\n",
				pool->name,
				blocks, pages * pool->blocks_per_page,
				pool->size, pages);
		size -= temp;
		next += temp;
	}
	up (&pools_lock);

	return PAGE_SIZE - size;
}
static DEVICE_ATTR (pools, S_IRUGO, show_pools, NULL);

/**
 * dma_pool_create - Creates a pool of consistent memory blocks, for dma.
 * @name: name of pool, for diagnostics
 * @dev: device that will be doing the DMA
 * @size: size of the blocks in this pool.
 * @align: alignment requirement for blocks; must be a power of two
 * @allocation: returned blocks won't cross this boundary (or zero)
 * Context: !in_interrupt()
 *
 * Returns a dma allocation pool with the requested characteristics, or
 * null if one can't be created.  Given one of these pools, dma_pool_alloc()
 * may be used to allocate memory.  Such memory will all have "consistent"
 * DMA mappings, accessible by the device and its driver without using
 * cache flushing primitives.  The actual size of blocks allocated may be
 * larger than requested because of alignment.
 *
 * If allocation is nonzero, objects returned from dma_pool_alloc() won't
 * cross that size boundary.  This is useful for devices which have
 * addressing restrictions on individual DMA transfers, such as not crossing
 * boundaries of 4KBytes.
 */
struct dma_pool *
dma_pool_create (const char *name, struct device *dev,
	size_t size, size_t align, size_t allocation)
{
	struct dma_pool		*retval;

	if (align == 0)
		align = 1;
	if (size == 0)
		return NULL;
	else if (size < align)
		size = align;
	else if ((size % align) != 0) {
		size += align + 1;
		size &= ~(align - 1);
	}

	if (allocation == 0) {
		if (PAGE_SIZE < size)
			allocation = size;
		else
			allocation = PAGE_SIZE;
		// FIXME: round up for less fragmentation
	} else if (allocation < size)
		return NULL;

	if (!(retval = kmalloc (sizeof *retval, SLAB_KERNEL)))
		return retval;

	strlcpy (retval->name, name, sizeof retval->name);

	retval->dev = dev;

	INIT_LIST_HEAD (&retval->page_list);
	spin_lock_init (&retval->lock);
	retval->size = size;
	retval->allocation = allocation;
	retval->blocks_per_page = allocation / size;
	init_waitqueue_head (&retval->waitq);

	if (dev) {
		int ret;

		down (&pools_lock);
		if (list_empty (&dev->dma_pools))
			ret = device_create_file (dev, &dev_attr_pools);
		else
			ret = 0;
		/* note:  not currently insisting "name" be unique */
		if (!ret)
			list_add (&retval->pools, &dev->dma_pools);
		else {
			kfree(retval);
			retval = NULL;
		}
		up (&pools_lock);
	} else
		INIT_LIST_HEAD (&retval->pools);

	return retval;
}


static struct dma_page *
pool_alloc_page (struct dma_pool *pool, gfp_t mem_flags)
{
	struct dma_page	*page;
	int		mapsize;

	mapsize = pool->blocks_per_page;
	mapsize = (mapsize + BITS_PER_LONG - 1) / BITS_PER_LONG;
	mapsize *= sizeof (long);

	page = (struct dma_page *) kmalloc (mapsize + sizeof *page, mem_flags);
	if (!page)
		return NULL;
	page->vaddr = dma_alloc_coherent (pool->dev,
					    pool->allocation,
					    &page->dma,
					    mem_flags);
	if (page->vaddr) {
		memset (page->bitmap, 0xff, mapsize);	// bit set == free
#ifdef	CONFIG_DEBUG_SLAB
		memset (page->vaddr, POOL_POISON_FREED, pool->allocation);
#endif
		list_add (&page->page_list, &pool->page_list);
		page->in_use = 0;
	} else {
		kfree (page);
		page = NULL;
	}
	return page;
}


static inline int
is_page_busy (int blocks, unsigned long *bitmap)
{
	while (blocks > 0) {
		if (*bitmap++ != ~0UL)
			return 1;
		blocks -= BITS_PER_LONG;
	}
	return 0;
}

static void
pool_free_page (struct dma_pool *pool, struct dma_page *page)
{
	dma_addr_t	dma = page->dma;

#ifdef	CONFIG_DEBUG_SLAB
	memset (page->vaddr, POOL_POISON_FREED, pool->allocation);
#endif
	dma_free_coherent (pool->dev, pool->allocation, page->vaddr, dma);
	list_del (&page->page_list);
	kfree (page);
}


/**
 * dma_pool_destroy - destroys a pool of dma memory blocks.
 * @pool: dma pool that will be destroyed
 * Context: !in_interrupt()
 *
 * Caller guarantees that no more memory from the pool is in use,
 * and that nothing will try to use the pool after this call.
 */
void
dma_pool_destroy (struct dma_pool *pool)
{
	down (&pools_lock);
	list_del (&pool->pools);
	if (pool->dev && list_empty (&pool->dev->dma_pools))
		device_remove_file (pool->dev, &dev_attr_pools);
	up (&pools_lock);

	while (!list_empty (&pool->page_list)) {
		struct dma_page		*page;
		page = list_entry (pool->page_list.next,
				struct dma_page, page_list);
		if (is_page_busy (pool->blocks_per_page, page->bitmap)) {
			if (pool->dev)
				dev_err(pool->dev, "dma_pool_destroy %s, %p busy\n",
					pool->name, page->vaddr);
			else
				printk (KERN_ERR "dma_pool_destroy %s, %p busy\n",
					pool->name, page->vaddr);
			/* leak the still-in-use consistent memory */
			list_del (&page->page_list);
			kfree (page);
		} else
			pool_free_page (pool, page);
	}

	kfree (pool);
}


/**
 * dma_pool_alloc - get a block of consistent memory
 * @pool: dma pool that will produce the block
 * @mem_flags: GFP_* bitmask
 * @handle: pointer to dma address of block
 *
 * This returns the kernel virtual address of a currently unused block,
 * and reports its dma address through the handle.
 * If such a memory block can't be allocated, null is returned.
 */
void *
dma_pool_alloc (struct dma_pool *pool, gfp_t mem_flags, dma_addr_t *handle)
{
	unsigned long		flags;
	struct dma_page		*page;
	int			map, block;
	size_t			offset;
	void			*retval;

restart:
	spin_lock_irqsave (&pool->lock, flags);
	list_for_each_entry(page, &pool->page_list, page_list) {
		int		i;
		/* only cachable accesses here ... */
		for (map = 0, i = 0;
				i < pool->blocks_per_page;
				i += BITS_PER_LONG, map++) {
			if (page->bitmap [map] == 0)
				continue;
			block = ffz (~ page->bitmap [map]);
			if ((i + block) < pool->blocks_per_page) {
				clear_bit (block, &page->bitmap [map]);
				offset = (BITS_PER_LONG * map) + block;
				offset *= pool->size;
				goto ready;
			}
		}
	}
	if (!(page = pool_alloc_page (pool, SLAB_ATOMIC))) {
		if (mem_flags & __GFP_WAIT) {
			DECLARE_WAITQUEUE (wait, current);

			current->state = TASK_INTERRUPTIBLE;
			add_wait_queue (&pool->waitq, &wait);
			spin_unlock_irqrestore (&pool->lock, flags);

			schedule_timeout (POOL_TIMEOUT_JIFFIES);

			remove_wait_queue (&pool->waitq, &wait);
			goto restart;
		}
		retval = NULL;
		goto done;
	}

	clear_bit (0, &page->bitmap [0]);
	offset = 0;
ready:
	page->in_use++;
	retval = offset + page->vaddr;
	*handle = offset + page->dma;
#ifdef	CONFIG_DEBUG_SLAB
	memset (retval, POOL_POISON_ALLOCATED, pool->size);
#endif
done:
	spin_unlock_irqrestore (&pool->lock, flags);
	return retval;
}


static struct dma_page *
pool_find_page (struct dma_pool *pool, dma_addr_t dma)
{
	unsigned long		flags;
	struct dma_page		*page;

	spin_lock_irqsave (&pool->lock, flags);
	list_for_each_entry(page, &pool->page_list, page_list) {
		if (dma < page->dma)
			continue;
		if (dma < (page->dma + pool->allocation))
			goto done;
	}
	page = NULL;
done:
	spin_unlock_irqrestore (&pool->lock, flags);
	return page;
}


/**
 * dma_pool_free - put block back into dma pool
 * @pool: the dma pool holding the block
 * @vaddr: virtual address of block
 * @dma: dma address of block
 *
 * Caller promises neither device nor driver will again touch this block
 * unless it is first re-allocated.
 */
void
dma_pool_free (struct dma_pool *pool, void *vaddr, dma_addr_t dma)
{
	struct dma_page		*page;
	unsigned long		flags;
	int			map, block;

	if ((page = pool_find_page (pool, dma)) == 0) {
		if (pool->dev)
			dev_err(pool->dev, "dma_pool_free %s, %p/%lx (bad dma)\n",
				pool->name, vaddr, (unsigned long) dma);
		else
			printk (KERN_ERR "dma_pool_free %s, %p/%lx (bad dma)\n",
				pool->name, vaddr, (unsigned long) dma);
		return;
	}

	block = dma - page->dma;
	block /= pool->size;
	map = block / BITS_PER_LONG;
	block %= BITS_PER_LONG;

#ifdef	CONFIG_DEBUG_SLAB
	if (((dma - page->dma) + (void *)page->vaddr) != vaddr) {
		if (pool->dev)
			dev_err(pool->dev, "dma_pool_free %s, %p (bad vaddr)/%Lx\n",
				pool->name, vaddr, (unsigned long long) dma);
		else
			printk (KERN_ERR "dma_pool_free %s, %p (bad vaddr)/%Lx\n",
				pool->name, vaddr, (unsigned long long) dma);
		return;
	}
	if (page->bitmap [map] & (1UL << block)) {
		if (pool->dev)
			dev_err(pool->dev, "dma_pool_free %s, dma %Lx already free\n",
				pool->name, (unsigned long long)dma);
		else
			printk (KERN_ERR "dma_pool_free %s, dma %Lx already free\n",
				pool->name, (unsigned long long)dma);
		return;
	}
	memset (vaddr, POOL_POISON_FREED, pool->size);
#endif

	spin_lock_irqsave (&pool->lock, flags);
	page->in_use--;
	set_bit (block, &page->bitmap [map]);
	if (waitqueue_active (&pool->waitq))
		wake_up (&pool->waitq);
	/*
	 * Resist a temptation to do
	 *    if (!is_page_busy(bpp, page->bitmap)) pool_free_page(pool, page);
	 * Better have a few empty pages hang around.
	 */
	spin_unlock_irqrestore (&pool->lock, flags);
}


EXPORT_SYMBOL (dma_pool_create);
EXPORT_SYMBOL (dma_pool_destroy);
EXPORT_SYMBOL (dma_pool_alloc);
EXPORT_SYMBOL (dma_pool_free);