summaryrefslogtreecommitdiffstats
path: root/drivers/base/dma-buf.c
blob: 24e88fe29ec19801f627e55b7b454fbbe8268181 (plain)
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
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
/*
 * Framework for buffer objects that can be shared across devices/subsystems.
 *
 * Copyright(C) 2011 Linaro Limited. All rights reserved.
 * Author: Sumit Semwal <sumit.semwal@ti.com>
 *
 * Many thanks to linaro-mm-sig list, and specially
 * Arnd Bergmann <arnd@arndb.de>, Rob Clark <rob@ti.com> and
 * Daniel Vetter <daniel@ffwll.ch> for their support in creation and
 * refining of this idea.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published by
 * the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <linux/fs.h>
#include <linux/slab.h>
#include <linux/dma-buf.h>
#include <linux/anon_inodes.h>
#include <linux/export.h>

static inline int is_dma_buf_file(struct file *);

static int dma_buf_release(struct inode *inode, struct file *file)
{
	struct dma_buf *dmabuf;

	if (!is_dma_buf_file(file))
		return -EINVAL;

	dmabuf = file->private_data;

	dmabuf->ops->release(dmabuf);
	kfree(dmabuf);
	return 0;
}

static int dma_buf_mmap_internal(struct file *file, struct vm_area_struct *vma)
{
	struct dma_buf *dmabuf;

	if (!is_dma_buf_file(file))
		return -EINVAL;

	dmabuf = file->private_data;

	/* check for overflowing the buffer's size */
	if (vma->vm_pgoff + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) >
	    dmabuf->size >> PAGE_SHIFT)
		return -EINVAL;

	return dmabuf->ops->mmap(dmabuf, vma);
}

static const struct file_operations dma_buf_fops = {
	.release	= dma_buf_release,
	.mmap		= dma_buf_mmap_internal,
};

/*
 * is_dma_buf_file - Check if struct file* is associated with dma_buf
 */
static inline int is_dma_buf_file(struct file *file)
{
	return file->f_op == &dma_buf_fops;
}

/**
 * dma_buf_export - Creates a new dma_buf, and associates an anon file
 * with this buffer, so it can be exported.
 * Also connect the allocator specific data and ops to the buffer.
 *
 * @priv:	[in]	Attach private data of allocator to this buffer
 * @ops:	[in]	Attach allocator-defined dma buf ops to the new buffer.
 * @size:	[in]	Size of the buffer
 * @flags:	[in]	mode flags for the file.
 *
 * Returns, on success, a newly created dma_buf object, which wraps the
 * supplied private data and operations for dma_buf_ops. On either missing
 * ops, or error in allocating struct dma_buf, will return negative error.
 *
 */
struct dma_buf *dma_buf_export(void *priv, const struct dma_buf_ops *ops,
				size_t size, int flags)
{
	struct dma_buf *dmabuf;
	struct file *file;

	if (WARN_ON(!priv || !ops
			  || !ops->map_dma_buf
			  || !ops->unmap_dma_buf
			  || !ops->release
			  || !ops->kmap_atomic
			  || !ops->kmap
			  || !ops->mmap)) {
		return ERR_PTR(-EINVAL);
	}

	dmabuf = kzalloc(sizeof(struct dma_buf), GFP_KERNEL);
	if (dmabuf == NULL)
		return ERR_PTR(-ENOMEM);

	dmabuf->priv = priv;
	dmabuf->ops = ops;
	dmabuf->size = size;

	file = anon_inode_getfile("dmabuf", &dma_buf_fops, dmabuf, flags);

	dmabuf->file = file;

	mutex_init(&dmabuf->lock);
	INIT_LIST_HEAD(&dmabuf->attachments);

	return dmabuf;
}
EXPORT_SYMBOL_GPL(dma_buf_export);


/**
 * dma_buf_fd - returns a file descriptor for the given dma_buf
 * @dmabuf:	[in]	pointer to dma_buf for which fd is required.
 * @flags:      [in]    flags to give to fd
 *
 * On success, returns an associated 'fd'. Else, returns error.
 */
int dma_buf_fd(struct dma_buf *dmabuf, int flags)
{
	int error, fd;

	if (!dmabuf || !dmabuf->file)
		return -EINVAL;

	error = get_unused_fd_flags(flags);
	if (error < 0)
		return error;
	fd = error;

	fd_install(fd, dmabuf->file);

	return fd;
}
EXPORT_SYMBOL_GPL(dma_buf_fd);

/**
 * dma_buf_get - returns the dma_buf structure related to an fd
 * @fd:	[in]	fd associated with the dma_buf to be returned
 *
 * On success, returns the dma_buf structure associated with an fd; uses
 * file's refcounting done by fget to increase refcount. returns ERR_PTR
 * otherwise.
 */
struct dma_buf *dma_buf_get(int fd)
{
	struct file *file;

	file = fget(fd);

	if (!file)
		return ERR_PTR(-EBADF);

	if (!is_dma_buf_file(file)) {
		fput(file);
		return ERR_PTR(-EINVAL);
	}

	return file->private_data;
}
EXPORT_SYMBOL_GPL(dma_buf_get);

/**
 * dma_buf_put - decreases refcount of the buffer
 * @dmabuf:	[in]	buffer to reduce refcount of
 *
 * Uses file's refcounting done implicitly by fput()
 */
void dma_buf_put(struct dma_buf *dmabuf)
{
	if (WARN_ON(!dmabuf || !dmabuf->file))
		return;

	fput(dmabuf->file);
}
EXPORT_SYMBOL_GPL(dma_buf_put);

/**
 * dma_buf_attach - Add the device to dma_buf's attachments list; optionally,
 * calls attach() of dma_buf_ops to allow device-specific attach functionality
 * @dmabuf:	[in]	buffer to attach device to.
 * @dev:	[in]	device to be attached.
 *
 * Returns struct dma_buf_attachment * for this attachment; may return negative
 * error codes.
 *
 */
struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,
					  struct device *dev)
{
	struct dma_buf_attachment *attach;
	int ret;

	if (WARN_ON(!dmabuf || !dev))
		return ERR_PTR(-EINVAL);

	attach = kzalloc(sizeof(struct dma_buf_attachment), GFP_KERNEL);
	if (attach == NULL)
		return ERR_PTR(-ENOMEM);

	attach->dev = dev;
	attach->dmabuf = dmabuf;

	mutex_lock(&dmabuf->lock);

	if (dmabuf->ops->attach) {
		ret = dmabuf->ops->attach(dmabuf, dev, attach);
		if (ret)
			goto err_attach;
	}
	list_add(&attach->node, &dmabuf->attachments);

	mutex_unlock(&dmabuf->lock);
	return attach;

err_attach:
	kfree(attach);
	mutex_unlock(&dmabuf->lock);
	return ERR_PTR(ret);
}
EXPORT_SYMBOL_GPL(dma_buf_attach);

/**
 * dma_buf_detach - Remove the given attachment from dmabuf's attachments list;
 * optionally calls detach() of dma_buf_ops for device-specific detach
 * @dmabuf:	[in]	buffer to detach from.
 * @attach:	[in]	attachment to be detached; is free'd after this call.
 *
 */
void dma_buf_detach(struct dma_buf *dmabuf, struct dma_buf_attachment *attach)
{
	if (WARN_ON(!dmabuf || !attach))
		return;

	mutex_lock(&dmabuf->lock);
	list_del(&attach->node);
	if (dmabuf->ops->detach)
		dmabuf->ops->detach(dmabuf, attach);

	mutex_unlock(&dmabuf->lock);
	kfree(attach);
}
EXPORT_SYMBOL_GPL(dma_buf_detach);

/**
 * dma_buf_map_attachment - Returns the scatterlist table of the attachment;
 * mapped into _device_ address space. Is a wrapper for map_dma_buf() of the
 * dma_buf_ops.
 * @attach:	[in]	attachment whose scatterlist is to be returned
 * @direction:	[in]	direction of DMA transfer
 *
 * Returns sg_table containing the scatterlist to be returned; may return NULL
 * or ERR_PTR.
 *
 */
struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *attach,
					enum dma_data_direction direction)
{
	struct sg_table *sg_table = ERR_PTR(-EINVAL);

	might_sleep();

	if (WARN_ON(!attach || !attach->dmabuf))
		return ERR_PTR(-EINVAL);

	sg_table = attach->dmabuf->ops->map_dma_buf(attach, direction);

	return sg_table;
}
EXPORT_SYMBOL_GPL(dma_buf_map_attachment);

/**
 * dma_buf_unmap_attachment - unmaps and decreases usecount of the buffer;might
 * deallocate the scatterlist associated. Is a wrapper for unmap_dma_buf() of
 * dma_buf_ops.
 * @attach:	[in]	attachment to unmap buffer from
 * @sg_table:	[in]	scatterlist info of the buffer to unmap
 * @direction:  [in]    direction of DMA transfer
 *
 */
void dma_buf_unmap_attachment(struct dma_buf_attachment *attach,
				struct sg_table *sg_table,
				enum dma_data_direction direction)
{
	if (WARN_ON(!attach || !attach->dmabuf || !sg_table))
		return;

	attach->dmabuf->ops->unmap_dma_buf(attach, sg_table,
						direction);
}
EXPORT_SYMBOL_GPL(dma_buf_unmap_attachment);


/**
 * dma_buf_begin_cpu_access - Must be called before accessing a dma_buf from the
 * cpu in the kernel context. Calls begin_cpu_access to allow exporter-specific
 * preparations. Coherency is only guaranteed in the specified range for the
 * specified access direction.
 * @dmabuf:	[in]	buffer to prepare cpu access for.
 * @start:	[in]	start of range for cpu access.
 * @len:	[in]	length of range for cpu access.
 * @direction:	[in]	length of range for cpu access.
 *
 * Can return negative error values, returns 0 on success.
 */
int dma_buf_begin_cpu_access(struct dma_buf *dmabuf, size_t start, size_t len,
			     enum dma_data_direction direction)
{
	int ret = 0;

	if (WARN_ON(!dmabuf))
		return -EINVAL;

	if (dmabuf->ops->begin_cpu_access)
		ret = dmabuf->ops->begin_cpu_access(dmabuf, start, len, direction);

	return ret;
}
EXPORT_SYMBOL_GPL(dma_buf_begin_cpu_access);

/**
 * dma_buf_end_cpu_access - Must be called after accessing a dma_buf from the
 * cpu in the kernel context. Calls end_cpu_access to allow exporter-specific
 * actions. Coherency is only guaranteed in the specified range for the
 * specified access direction.
 * @dmabuf:	[in]	buffer to complete cpu access for.
 * @start:	[in]	start of range for cpu access.
 * @len:	[in]	length of range for cpu access.
 * @direction:	[in]	length of range for cpu access.
 *
 * This call must always succeed.
 */
void dma_buf_end_cpu_access(struct dma_buf *dmabuf, size_t start, size_t len,
			    enum dma_data_direction direction)
{
	WARN_ON(!dmabuf);

	if (dmabuf->ops->end_cpu_access)
		dmabuf->ops->end_cpu_access(dmabuf, start, len, direction);
}
EXPORT_SYMBOL_GPL(dma_buf_end_cpu_access);

/**
 * dma_buf_kmap_atomic - Map a page of the buffer object into kernel address
 * space. The same restrictions as for kmap_atomic and friends apply.
 * @dmabuf:	[in]	buffer to map page from.
 * @page_num:	[in]	page in PAGE_SIZE units to map.
 *
 * This call must always succeed, any necessary preparations that might fail
 * need to be done in begin_cpu_access.
 */
void *dma_buf_kmap_atomic(struct dma_buf *dmabuf, unsigned long page_num)
{
	WARN_ON(!dmabuf);

	return dmabuf->ops->kmap_atomic(dmabuf, page_num);
}
EXPORT_SYMBOL_GPL(dma_buf_kmap_atomic);

/**
 * dma_buf_kunmap_atomic - Unmap a page obtained by dma_buf_kmap_atomic.
 * @dmabuf:	[in]	buffer to unmap page from.
 * @page_num:	[in]	page in PAGE_SIZE units to unmap.
 * @vaddr:	[in]	kernel space pointer obtained from dma_buf_kmap_atomic.
 *
 * This call must always succeed.
 */
void dma_buf_kunmap_atomic(struct dma_buf *dmabuf, unsigned long page_num,
			   void *vaddr)
{
	WARN_ON(!dmabuf);

	if (dmabuf->ops->kunmap_atomic)
		dmabuf->ops->kunmap_atomic(dmabuf, page_num, vaddr);
}
EXPORT_SYMBOL_GPL(dma_buf_kunmap_atomic);

/**
 * dma_buf_kmap - Map a page of the buffer object into kernel address space. The
 * same restrictions as for kmap and friends apply.
 * @dmabuf:	[in]	buffer to map page from.
 * @page_num:	[in]	page in PAGE_SIZE units to map.
 *
 * This call must always succeed, any necessary preparations that might fail
 * need to be done in begin_cpu_access.
 */
void *dma_buf_kmap(struct dma_buf *dmabuf, unsigned long page_num)
{
	WARN_ON(!dmabuf);

	return dmabuf->ops->kmap(dmabuf, page_num);
}
EXPORT_SYMBOL_GPL(dma_buf_kmap);

/**
 * dma_buf_kunmap - Unmap a page obtained by dma_buf_kmap.
 * @dmabuf:	[in]	buffer to unmap page from.
 * @page_num:	[in]	page in PAGE_SIZE units to unmap.
 * @vaddr:	[in]	kernel space pointer obtained from dma_buf_kmap.
 *
 * This call must always succeed.
 */
void dma_buf_kunmap(struct dma_buf *dmabuf, unsigned long page_num,
		    void *vaddr)
{
	WARN_ON(!dmabuf);

	if (dmabuf->ops->kunmap)
		dmabuf->ops->kunmap(dmabuf, page_num, vaddr);
}
EXPORT_SYMBOL_GPL(dma_buf_kunmap);


/**
 * dma_buf_mmap - Setup up a userspace mmap with the given vma
 * @dmabuf:	[in]	buffer that should back the vma
 * @vma:	[in]	vma for the mmap
 * @pgoff:	[in]	offset in pages where this mmap should start within the
 * 			dma-buf buffer.
 *
 * This function adjusts the passed in vma so that it points at the file of the
 * dma_buf operation. It alsog adjusts the starting pgoff and does bounds
 * checking on the size of the vma. Then it calls the exporters mmap function to
 * set up the mapping.
 *
 * Can return negative error values, returns 0 on success.
 */
int dma_buf_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma,
		 unsigned long pgoff)
{
	if (WARN_ON(!dmabuf || !vma))
		return -EINVAL;

	/* check for offset overflow */
	if (pgoff + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) < pgoff)
		return -EOVERFLOW;

	/* check for overflowing the buffer's size */
	if (pgoff + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) >
	    dmabuf->size >> PAGE_SHIFT)
		return -EINVAL;

	/* readjust the vma */
	if (vma->vm_file)
		fput(vma->vm_file);

	vma->vm_file = dmabuf->file;
	get_file(vma->vm_file);

	vma->vm_pgoff = pgoff;

	return dmabuf->ops->mmap(dmabuf, vma);
}
EXPORT_SYMBOL_GPL(dma_buf_mmap);

/**
 * dma_buf_vmap - Create virtual mapping for the buffer object into kernel
 * address space. Same restrictions as for vmap and friends apply.
 * @dmabuf:	[in]	buffer to vmap
 *
 * This call may fail due to lack of virtual mapping address space.
 * These calls are optional in drivers. The intended use for them
 * is for mapping objects linear in kernel space for high use objects.
 * Please attempt to use kmap/kunmap before thinking about these interfaces.
 */
void *dma_buf_vmap(struct dma_buf *dmabuf)
{
	if (WARN_ON(!dmabuf))
		return NULL;

	if (dmabuf->ops->vmap)
		return dmabuf->ops->vmap(dmabuf);
	return NULL;
}
EXPORT_SYMBOL_GPL(dma_buf_vmap);

/**
 * dma_buf_vunmap - Unmap a vmap obtained by dma_buf_vmap.
 * @dmabuf:	[in]	buffer to vunmap
 */
void dma_buf_vunmap(struct dma_buf *dmabuf, void *vaddr)
{
	if (WARN_ON(!dmabuf))
		return;

	if (dmabuf->ops->vunmap)
		dmabuf->ops->vunmap(dmabuf, vaddr);
}
EXPORT_SYMBOL_GPL(dma_buf_vunmap);