1 /* SPDX-License-Identifier: GPL-2.0-only */
2 /*
3  * Header file for dma buffer sharing framework.
4  *
5  * Copyright(C) 2011 Linaro Limited. All rights reserved.
6  * Author: Sumit Semwal <sumit.semwal@ti.com>
7  *
8  * Many thanks to linaro-mm-sig list, and specially
9  * Arnd Bergmann <arnd@arndb.de>, Rob Clark <rob@ti.com> and
10  * Daniel Vetter <daniel@ffwll.ch> for their support in creation and
11  * refining of this idea.
12  */
13 #ifndef __DMA_BUF_H__
14 #define __DMA_BUF_H__
15 
16 #include <linux/iosys-map.h>
17 #include <linux/file.h>
18 #include <linux/err.h>
19 #include <linux/scatterlist.h>
20 #include <linux/list.h>
21 #include <linux/dma-mapping.h>
22 #include <linux/fs.h>
23 #include <linux/dma-fence.h>
24 #include <linux/wait.h>
25 
26 struct device;
27 struct dma_buf;
28 struct dma_buf_attachment;
29 
30 /**
31  * struct dma_buf_ops - operations possible on struct dma_buf
32  * @vmap: [optional] creates a virtual mapping for the buffer into kernel
33  *	  address space. Same restrictions as for vmap and friends apply.
34  * @vunmap: [optional] unmaps a vmap from the buffer
35  */
36 struct dma_buf_ops {
37 	/**
38 	  * @cache_sgt_mapping:
39 	  *
40 	  * If true the framework will cache the first mapping made for each
41 	  * attachment. This avoids creating mappings for attachments multiple
42 	  * times.
43 	  */
44 	bool cache_sgt_mapping;
45 
46 	/**
47 	 * @attach:
48 	 *
49 	 * This is called from dma_buf_attach() to make sure that a given
50 	 * &dma_buf_attachment.dev can access the provided &dma_buf. Exporters
51 	 * which support buffer objects in special locations like VRAM or
52 	 * device-specific carveout areas should check whether the buffer could
53 	 * be move to system memory (or directly accessed by the provided
54 	 * device), and otherwise need to fail the attach operation.
55 	 *
56 	 * The exporter should also in general check whether the current
57 	 * allocation fulfills the DMA constraints of the new device. If this
58 	 * is not the case, and the allocation cannot be moved, it should also
59 	 * fail the attach operation.
60 	 *
61 	 * Any exporter-private housekeeping data can be stored in the
62 	 * &dma_buf_attachment.priv pointer.
63 	 *
64 	 * This callback is optional.
65 	 *
66 	 * Returns:
67 	 *
68 	 * 0 on success, negative error code on failure. It might return -EBUSY
69 	 * to signal that backing storage is already allocated and incompatible
70 	 * with the requirements of requesting device.
71 	 */
72 	int (*attach)(struct dma_buf *, struct dma_buf_attachment *);
73 
74 	/**
75 	 * @detach:
76 	 *
77 	 * This is called by dma_buf_detach() to release a &dma_buf_attachment.
78 	 * Provided so that exporters can clean up any housekeeping for an
79 	 * &dma_buf_attachment.
80 	 *
81 	 * This callback is optional.
82 	 */
83 	void (*detach)(struct dma_buf *, struct dma_buf_attachment *);
84 
85 	/**
86 	 * @pin:
87 	 *
88 	 * This is called by dma_buf_pin() and lets the exporter know that the
89 	 * DMA-buf can't be moved any more. Ideally, the exporter should
90 	 * pin the buffer so that it is generally accessible by all
91 	 * devices.
92 	 *
93 	 * This is called with the &dmabuf.resv object locked and is mutual
94 	 * exclusive with @cache_sgt_mapping.
95 	 *
96 	 * This is called automatically for non-dynamic importers from
97 	 * dma_buf_attach().
98 	 *
99 	 * Note that similar to non-dynamic exporters in their @map_dma_buf
100 	 * callback the driver must guarantee that the memory is available for
101 	 * use and cleared of any old data by the time this function returns.
102 	 * Drivers which pipeline their buffer moves internally must wait for
103 	 * all moves and clears to complete.
104 	 *
105 	 * Returns:
106 	 *
107 	 * 0 on success, negative error code on failure.
108 	 */
109 	int (*pin)(struct dma_buf_attachment *attach);
110 
111 	/**
112 	 * @unpin:
113 	 *
114 	 * This is called by dma_buf_unpin() and lets the exporter know that the
115 	 * DMA-buf can be moved again.
116 	 *
117 	 * This is called with the dmabuf->resv object locked and is mutual
118 	 * exclusive with @cache_sgt_mapping.
119 	 *
120 	 * This callback is optional.
121 	 */
122 	void (*unpin)(struct dma_buf_attachment *attach);
123 
124 	/**
125 	 * @map_dma_buf:
126 	 *
127 	 * This is called by dma_buf_map_attachment() and is used to map a
128 	 * shared &dma_buf into device address space, and it is mandatory. It
129 	 * can only be called if @attach has been called successfully.
130 	 *
131 	 * This call may sleep, e.g. when the backing storage first needs to be
132 	 * allocated, or moved to a location suitable for all currently attached
133 	 * devices.
134 	 *
135 	 * Note that any specific buffer attributes required for this function
136 	 * should get added to device_dma_parameters accessible via
137 	 * &device.dma_params from the &dma_buf_attachment. The @attach callback
138 	 * should also check these constraints.
139 	 *
140 	 * If this is being called for the first time, the exporter can now
141 	 * choose to scan through the list of attachments for this buffer,
142 	 * collate the requirements of the attached devices, and choose an
143 	 * appropriate backing storage for the buffer.
144 	 *
145 	 * Based on enum dma_data_direction, it might be possible to have
146 	 * multiple users accessing at the same time (for reading, maybe), or
147 	 * any other kind of sharing that the exporter might wish to make
148 	 * available to buffer-users.
149 	 *
150 	 * This is always called with the dmabuf->resv object locked when
151 	 * the dynamic_mapping flag is true.
152 	 *
153 	 * Note that for non-dynamic exporters the driver must guarantee that
154 	 * that the memory is available for use and cleared of any old data by
155 	 * the time this function returns.  Drivers which pipeline their buffer
156 	 * moves internally must wait for all moves and clears to complete.
157 	 * Dynamic exporters do not need to follow this rule: For non-dynamic
158 	 * importers the buffer is already pinned through @pin, which has the
159 	 * same requirements. Dynamic importers otoh are required to obey the
160 	 * dma_resv fences.
161 	 *
162 	 * Returns:
163 	 *
164 	 * A &sg_table scatter list of the backing storage of the DMA buffer,
165 	 * already mapped into the device address space of the &device attached
166 	 * with the provided &dma_buf_attachment. The addresses and lengths in
167 	 * the scatter list are PAGE_SIZE aligned.
168 	 *
169 	 * On failure, returns a negative error value wrapped into a pointer.
170 	 * May also return -EINTR when a signal was received while being
171 	 * blocked.
172 	 *
173 	 * Note that exporters should not try to cache the scatter list, or
174 	 * return the same one for multiple calls. Caching is done either by the
175 	 * DMA-BUF code (for non-dynamic importers) or the importer. Ownership
176 	 * of the scatter list is transferred to the caller, and returned by
177 	 * @unmap_dma_buf.
178 	 */
179 	struct sg_table * (*map_dma_buf)(struct dma_buf_attachment *,
180 					 enum dma_data_direction);
181 	/**
182 	 * @unmap_dma_buf:
183 	 *
184 	 * This is called by dma_buf_unmap_attachment() and should unmap and
185 	 * release the &sg_table allocated in @map_dma_buf, and it is mandatory.
186 	 * For static dma_buf handling this might also unpin the backing
187 	 * storage if this is the last mapping of the DMA buffer.
188 	 */
189 	void (*unmap_dma_buf)(struct dma_buf_attachment *,
190 			      struct sg_table *,
191 			      enum dma_data_direction);
192 
193 	/* TODO: Add try_map_dma_buf version, to return immed with -EBUSY
194 	 * if the call would block.
195 	 */
196 
197 	/**
198 	 * @release:
199 	 *
200 	 * Called after the last dma_buf_put to release the &dma_buf, and
201 	 * mandatory.
202 	 */
203 	void (*release)(struct dma_buf *);
204 
205 	/**
206 	 * @begin_cpu_access:
207 	 *
208 	 * This is called from dma_buf_begin_cpu_access() and allows the
209 	 * exporter to ensure that the memory is actually coherent for cpu
210 	 * access. The exporter also needs to ensure that cpu access is coherent
211 	 * for the access direction. The direction can be used by the exporter
212 	 * to optimize the cache flushing, i.e. access with a different
213 	 * direction (read instead of write) might return stale or even bogus
214 	 * data (e.g. when the exporter needs to copy the data to temporary
215 	 * storage).
216 	 *
217 	 * Note that this is both called through the DMA_BUF_IOCTL_SYNC IOCTL
218 	 * command for userspace mappings established through @mmap, and also
219 	 * for kernel mappings established with @vmap.
220 	 *
221 	 * This callback is optional.
222 	 *
223 	 * Returns:
224 	 *
225 	 * 0 on success or a negative error code on failure. This can for
226 	 * example fail when the backing storage can't be allocated. Can also
227 	 * return -ERESTARTSYS or -EINTR when the call has been interrupted and
228 	 * needs to be restarted.
229 	 */
230 	int (*begin_cpu_access)(struct dma_buf *, enum dma_data_direction);
231 
232 	/**
233 	 * @end_cpu_access:
234 	 *
235 	 * This is called from dma_buf_end_cpu_access() when the importer is
236 	 * done accessing the CPU. The exporter can use this to flush caches and
237 	 * undo anything else done in @begin_cpu_access.
238 	 *
239 	 * This callback is optional.
240 	 *
241 	 * Returns:
242 	 *
243 	 * 0 on success or a negative error code on failure. Can return
244 	 * -ERESTARTSYS or -EINTR when the call has been interrupted and needs
245 	 * to be restarted.
246 	 */
247 	int (*end_cpu_access)(struct dma_buf *, enum dma_data_direction);
248 
249 	/**
250 	 * @mmap:
251 	 *
252 	 * This callback is used by the dma_buf_mmap() function
253 	 *
254 	 * Note that the mapping needs to be incoherent, userspace is expected
255 	 * to bracket CPU access using the DMA_BUF_IOCTL_SYNC interface.
256 	 *
257 	 * Because dma-buf buffers have invariant size over their lifetime, the
258 	 * dma-buf core checks whether a vma is too large and rejects such
259 	 * mappings. The exporter hence does not need to duplicate this check.
260 	 * Drivers do not need to check this themselves.
261 	 *
262 	 * If an exporter needs to manually flush caches and hence needs to fake
263 	 * coherency for mmap support, it needs to be able to zap all the ptes
264 	 * pointing at the backing storage. Now linux mm needs a struct
265 	 * address_space associated with the struct file stored in vma->vm_file
266 	 * to do that with the function unmap_mapping_range. But the dma_buf
267 	 * framework only backs every dma_buf fd with the anon_file struct file,
268 	 * i.e. all dma_bufs share the same file.
269 	 *
270 	 * Hence exporters need to setup their own file (and address_space)
271 	 * association by setting vma->vm_file and adjusting vma->vm_pgoff in
272 	 * the dma_buf mmap callback. In the specific case of a gem driver the
273 	 * exporter could use the shmem file already provided by gem (and set
274 	 * vm_pgoff = 0). Exporters can then zap ptes by unmapping the
275 	 * corresponding range of the struct address_space associated with their
276 	 * own file.
277 	 *
278 	 * This callback is optional.
279 	 *
280 	 * Returns:
281 	 *
282 	 * 0 on success or a negative error code on failure.
283 	 */
284 	int (*mmap)(struct dma_buf *, struct vm_area_struct *vma);
285 
286 	int (*vmap)(struct dma_buf *dmabuf, struct iosys_map *map);
287 	void (*vunmap)(struct dma_buf *dmabuf, struct iosys_map *map);
288 };
289 
290 /**
291  * struct dma_buf - shared buffer object
292  *
293  * This represents a shared buffer, created by calling dma_buf_export(). The
294  * userspace representation is a normal file descriptor, which can be created by
295  * calling dma_buf_fd().
296  *
297  * Shared dma buffers are reference counted using dma_buf_put() and
298  * get_dma_buf().
299  *
300  * Device DMA access is handled by the separate &struct dma_buf_attachment.
301  */
302 struct dma_buf {
303 	/**
304 	 * @size:
305 	 *
306 	 * Size of the buffer; invariant over the lifetime of the buffer.
307 	 */
308 	size_t size;
309 
310 	/**
311 	 * @file:
312 	 *
313 	 * File pointer used for sharing buffers across, and for refcounting.
314 	 * See dma_buf_get() and dma_buf_put().
315 	 */
316 	struct file *file;
317 
318 	/**
319 	 * @attachments:
320 	 *
321 	 * List of dma_buf_attachment that denotes all devices attached,
322 	 * protected by &dma_resv lock @resv.
323 	 */
324 	struct list_head attachments;
325 
326 	/** @ops: dma_buf_ops associated with this buffer object. */
327 	const struct dma_buf_ops *ops;
328 
329 	/**
330 	 * @lock:
331 	 *
332 	 * Used internally to serialize list manipulation, attach/detach and
333 	 * vmap/unmap. Note that in many cases this is superseeded by
334 	 * dma_resv_lock() on @resv.
335 	 */
336 	struct mutex lock;
337 
338 	/**
339 	 * @vmapping_counter:
340 	 *
341 	 * Used internally to refcnt the vmaps returned by dma_buf_vmap().
342 	 * Protected by @lock.
343 	 */
344 	unsigned vmapping_counter;
345 
346 	/**
347 	 * @vmap_ptr:
348 	 * The current vmap ptr if @vmapping_counter > 0. Protected by @lock.
349 	 */
350 	struct iosys_map vmap_ptr;
351 
352 	/**
353 	 * @exp_name:
354 	 *
355 	 * Name of the exporter; useful for debugging. See the
356 	 * DMA_BUF_SET_NAME IOCTL.
357 	 */
358 	const char *exp_name;
359 
360 	/**
361 	 * @name:
362 	 *
363 	 * Userspace-provided name; useful for accounting and debugging,
364 	 * protected by dma_resv_lock() on @resv and @name_lock for read access.
365 	 */
366 	const char *name;
367 
368 	/** @name_lock: Spinlock to protect name acces for read access. */
369 	spinlock_t name_lock;
370 
371 	/**
372 	 * @owner:
373 	 *
374 	 * Pointer to exporter module; used for refcounting when exporter is a
375 	 * kernel module.
376 	 */
377 	struct module *owner;
378 
379 	/** @list_node: node for dma_buf accounting and debugging. */
380 	struct list_head list_node;
381 
382 	/** @priv: exporter specific private data for this buffer object. */
383 	void *priv;
384 
385 	/**
386 	 * @resv:
387 	 *
388 	 * Reservation object linked to this dma-buf.
389 	 *
390 	 * IMPLICIT SYNCHRONIZATION RULES:
391 	 *
392 	 * Drivers which support implicit synchronization of buffer access as
393 	 * e.g. exposed in `Implicit Fence Poll Support`_ must follow the
394 	 * below rules.
395 	 *
396 	 * - Drivers must add a read fence through dma_resv_add_fence() with the
397 	 *   DMA_RESV_USAGE_READ flag for anything the userspace API considers a
398 	 *   read access. This highly depends upon the API and window system.
399 	 *
400 	 * - Similarly drivers must add a write fence through
401 	 *   dma_resv_add_fence() with the DMA_RESV_USAGE_WRITE flag for
402 	 *   anything the userspace API considers write access.
403 	 *
404 	 * - Drivers may just always add a write fence, since that only
405 	 *   causes unecessarily synchronization, but no correctness issues.
406 	 *
407 	 * - Some drivers only expose a synchronous userspace API with no
408 	 *   pipelining across drivers. These do not set any fences for their
409 	 *   access. An example here is v4l.
410 	 *
411 	 * - Driver should use dma_resv_usage_rw() when retrieving fences as
412 	 *   dependency for implicit synchronization.
413 	 *
414 	 * DYNAMIC IMPORTER RULES:
415 	 *
416 	 * Dynamic importers, see dma_buf_attachment_is_dynamic(), have
417 	 * additional constraints on how they set up fences:
418 	 *
419 	 * - Dynamic importers must obey the write fences and wait for them to
420 	 *   signal before allowing access to the buffer's underlying storage
421 	 *   through the device.
422 	 *
423 	 * - Dynamic importers should set fences for any access that they can't
424 	 *   disable immediately from their &dma_buf_attach_ops.move_notify
425 	 *   callback.
426 	 *
427 	 * IMPORTANT:
428 	 *
429 	 * All drivers and memory management related functions must obey the
430 	 * struct dma_resv rules, specifically the rules for updating and
431 	 * obeying fences. See enum dma_resv_usage for further descriptions.
432 	 */
433 	struct dma_resv *resv;
434 
435 	/** @poll: for userspace poll support */
436 	wait_queue_head_t poll;
437 
438 	/** @cb_in: for userspace poll support */
439 	/** @cb_out: for userspace poll support */
440 	struct dma_buf_poll_cb_t {
441 		struct dma_fence_cb cb;
442 		wait_queue_head_t *poll;
443 
444 		__poll_t active;
445 	} cb_in, cb_out;
446 #ifdef CONFIG_DMABUF_SYSFS_STATS
447 	/**
448 	 * @sysfs_entry:
449 	 *
450 	 * For exposing information about this buffer in sysfs. See also
451 	 * `DMA-BUF statistics`_ for the uapi this enables.
452 	 */
453 	struct dma_buf_sysfs_entry {
454 		struct kobject kobj;
455 		struct dma_buf *dmabuf;
456 	} *sysfs_entry;
457 #endif
458 };
459 
460 /**
461  * struct dma_buf_attach_ops - importer operations for an attachment
462  *
463  * Attachment operations implemented by the importer.
464  */
465 struct dma_buf_attach_ops {
466 	/**
467 	 * @allow_peer2peer:
468 	 *
469 	 * If this is set to true the importer must be able to handle peer
470 	 * resources without struct pages.
471 	 */
472 	bool allow_peer2peer;
473 
474 	/**
475 	 * @move_notify: [optional] notification that the DMA-buf is moving
476 	 *
477 	 * If this callback is provided the framework can avoid pinning the
478 	 * backing store while mappings exists.
479 	 *
480 	 * This callback is called with the lock of the reservation object
481 	 * associated with the dma_buf held and the mapping function must be
482 	 * called with this lock held as well. This makes sure that no mapping
483 	 * is created concurrently with an ongoing move operation.
484 	 *
485 	 * Mappings stay valid and are not directly affected by this callback.
486 	 * But the DMA-buf can now be in a different physical location, so all
487 	 * mappings should be destroyed and re-created as soon as possible.
488 	 *
489 	 * New mappings can be created after this callback returns, and will
490 	 * point to the new location of the DMA-buf.
491 	 */
492 	void (*move_notify)(struct dma_buf_attachment *attach);
493 };
494 
495 /**
496  * struct dma_buf_attachment - holds device-buffer attachment data
497  * @dmabuf: buffer for this attachment.
498  * @dev: device attached to the buffer.
499  * @node: list of dma_buf_attachment, protected by dma_resv lock of the dmabuf.
500  * @sgt: cached mapping.
501  * @dir: direction of cached mapping.
502  * @peer2peer: true if the importer can handle peer resources without pages.
503  * @priv: exporter specific attachment data.
504  * @importer_ops: importer operations for this attachment, if provided
505  * dma_buf_map/unmap_attachment() must be called with the dma_resv lock held.
506  * @importer_priv: importer specific attachment data.
507  *
508  * This structure holds the attachment information between the dma_buf buffer
509  * and its user device(s). The list contains one attachment struct per device
510  * attached to the buffer.
511  *
512  * An attachment is created by calling dma_buf_attach(), and released again by
513  * calling dma_buf_detach(). The DMA mapping itself needed to initiate a
514  * transfer is created by dma_buf_map_attachment() and freed again by calling
515  * dma_buf_unmap_attachment().
516  */
517 struct dma_buf_attachment {
518 	struct dma_buf *dmabuf;
519 	struct device *dev;
520 	struct list_head node;
521 	struct sg_table *sgt;
522 	enum dma_data_direction dir;
523 	bool peer2peer;
524 	const struct dma_buf_attach_ops *importer_ops;
525 	void *importer_priv;
526 	void *priv;
527 };
528 
529 /**
530  * struct dma_buf_export_info - holds information needed to export a dma_buf
531  * @exp_name:	name of the exporter - useful for debugging.
532  * @owner:	pointer to exporter module - used for refcounting kernel module
533  * @ops:	Attach allocator-defined dma buf ops to the new buffer
534  * @size:	Size of the buffer - invariant over the lifetime of the buffer
535  * @flags:	mode flags for the file
536  * @resv:	reservation-object, NULL to allocate default one
537  * @priv:	Attach private data of allocator to this buffer
538  *
539  * This structure holds the information required to export the buffer. Used
540  * with dma_buf_export() only.
541  */
542 struct dma_buf_export_info {
543 	const char *exp_name;
544 	struct module *owner;
545 	const struct dma_buf_ops *ops;
546 	size_t size;
547 	int flags;
548 	struct dma_resv *resv;
549 	void *priv;
550 };
551 
552 /**
553  * DEFINE_DMA_BUF_EXPORT_INFO - helper macro for exporters
554  * @name: export-info name
555  *
556  * DEFINE_DMA_BUF_EXPORT_INFO macro defines the &struct dma_buf_export_info,
557  * zeroes it out and pre-populates exp_name in it.
558  */
559 #define DEFINE_DMA_BUF_EXPORT_INFO(name)	\
560 	struct dma_buf_export_info name = { .exp_name = KBUILD_MODNAME, \
561 					 .owner = THIS_MODULE }
562 
563 /**
564  * get_dma_buf - convenience wrapper for get_file.
565  * @dmabuf:	[in]	pointer to dma_buf
566  *
567  * Increments the reference count on the dma-buf, needed in case of drivers
568  * that either need to create additional references to the dmabuf on the
569  * kernel side.  For example, an exporter that needs to keep a dmabuf ptr
570  * so that subsequent exports don't create a new dmabuf.
571  */
get_dma_buf(struct dma_buf * dmabuf)572 static inline void get_dma_buf(struct dma_buf *dmabuf)
573 {
574 	get_file(dmabuf->file);
575 }
576 
577 /**
578  * dma_buf_is_dynamic - check if a DMA-buf uses dynamic mappings.
579  * @dmabuf: the DMA-buf to check
580  *
581  * Returns true if a DMA-buf exporter wants to be called with the dma_resv
582  * locked for the map/unmap callbacks, false if it doesn't wants to be called
583  * with the lock held.
584  */
dma_buf_is_dynamic(struct dma_buf * dmabuf)585 static inline bool dma_buf_is_dynamic(struct dma_buf *dmabuf)
586 {
587 	return !!dmabuf->ops->pin;
588 }
589 
590 /**
591  * dma_buf_attachment_is_dynamic - check if a DMA-buf attachment uses dynamic
592  * mappings
593  * @attach: the DMA-buf attachment to check
594  *
595  * Returns true if a DMA-buf importer wants to call the map/unmap functions with
596  * the dma_resv lock held.
597  */
598 static inline bool
dma_buf_attachment_is_dynamic(struct dma_buf_attachment * attach)599 dma_buf_attachment_is_dynamic(struct dma_buf_attachment *attach)
600 {
601 	return !!attach->importer_ops;
602 }
603 
604 struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,
605 					  struct device *dev);
606 struct dma_buf_attachment *
607 dma_buf_dynamic_attach(struct dma_buf *dmabuf, struct device *dev,
608 		       const struct dma_buf_attach_ops *importer_ops,
609 		       void *importer_priv);
610 void dma_buf_detach(struct dma_buf *dmabuf,
611 		    struct dma_buf_attachment *attach);
612 int dma_buf_pin(struct dma_buf_attachment *attach);
613 void dma_buf_unpin(struct dma_buf_attachment *attach);
614 
615 struct dma_buf *dma_buf_export(const struct dma_buf_export_info *exp_info);
616 
617 int dma_buf_fd(struct dma_buf *dmabuf, int flags);
618 struct dma_buf *dma_buf_get(int fd);
619 void dma_buf_put(struct dma_buf *dmabuf);
620 
621 struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *,
622 					enum dma_data_direction);
623 void dma_buf_unmap_attachment(struct dma_buf_attachment *, struct sg_table *,
624 				enum dma_data_direction);
625 void dma_buf_move_notify(struct dma_buf *dma_buf);
626 int dma_buf_begin_cpu_access(struct dma_buf *dma_buf,
627 			     enum dma_data_direction dir);
628 int dma_buf_end_cpu_access(struct dma_buf *dma_buf,
629 			   enum dma_data_direction dir);
630 
631 int dma_buf_mmap(struct dma_buf *, struct vm_area_struct *,
632 		 unsigned long);
633 int dma_buf_vmap(struct dma_buf *dmabuf, struct iosys_map *map);
634 void dma_buf_vunmap(struct dma_buf *dmabuf, struct iosys_map *map);
635 #endif /* __DMA_BUF_H__ */
636