2 * Framework for buffer objects that can be shared across devices/subsystems.
4 * Copyright(C) 2011 Linaro Limited. All rights reserved.
5 * Author: Sumit Semwal <sumit.semwal@ti.com>
7 * Many thanks to linaro-mm-sig list, and specially
8 * Arnd Bergmann <arnd@arndb.de>, Rob Clark <rob@ti.com> and
9 * Daniel Vetter <daniel@ffwll.ch> for their support in creation and
10 * refining of this idea.
12 * This program is free software; you can redistribute it and/or modify it
13 * under the terms of the GNU General Public License version 2 as published by
14 * the Free Software Foundation.
16 * This program is distributed in the hope that it will be useful, but WITHOUT
17 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
18 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
21 * You should have received a copy of the GNU General Public License along with
22 * this program. If not, see <http://www.gnu.org/licenses/>.
26 #include <linux/slab.h>
27 #include <linux/dma-buf.h>
28 #include <linux/anon_inodes.h>
29 #include <linux/export.h>
31 static inline int is_dma_buf_file(struct file *);
33 static int dma_buf_release(struct inode *inode, struct file *file)
35 struct dma_buf *dmabuf;
37 if (!is_dma_buf_file(file))
40 dmabuf = file->private_data;
42 dmabuf->ops->release(dmabuf);
43 kds_resource_term(&dmabuf->kds);
48 static int dma_buf_mmap_internal(struct file *file, struct vm_area_struct *vma)
50 struct dma_buf *dmabuf;
52 if (!is_dma_buf_file(file))
55 dmabuf = file->private_data;
57 /* check for overflowing the buffer's size */
58 if (vma->vm_pgoff + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) >
59 dmabuf->size >> PAGE_SHIFT)
62 return dmabuf->ops->mmap(dmabuf, vma);
65 static const struct file_operations dma_buf_fops = {
66 .release = dma_buf_release,
67 .mmap = dma_buf_mmap_internal,
71 * is_dma_buf_file - Check if struct file* is associated with dma_buf
73 static inline int is_dma_buf_file(struct file *file)
75 return file->f_op == &dma_buf_fops;
79 * dma_buf_export - Creates a new dma_buf, and associates an anon file
80 * with this buffer, so it can be exported.
81 * Also connect the allocator specific data and ops to the buffer.
83 * @priv: [in] Attach private data of allocator to this buffer
84 * @ops: [in] Attach allocator-defined dma buf ops to the new buffer.
85 * @size: [in] Size of the buffer
86 * @flags: [in] mode flags for the file.
88 * Returns, on success, a newly created dma_buf object, which wraps the
89 * supplied private data and operations for dma_buf_ops. On either missing
90 * ops, or error in allocating struct dma_buf, will return negative error.
93 struct dma_buf *dma_buf_export(void *priv, const struct dma_buf_ops *ops,
94 size_t size, int flags)
96 struct dma_buf *dmabuf;
99 if (WARN_ON(!priv || !ops
101 || !ops->unmap_dma_buf
106 return ERR_PTR(-EINVAL);
109 dmabuf = kzalloc(sizeof(struct dma_buf), GFP_KERNEL);
111 return ERR_PTR(-ENOMEM);
117 file = anon_inode_getfile("dmabuf", &dma_buf_fops, dmabuf, flags);
121 mutex_init(&dmabuf->lock);
122 INIT_LIST_HEAD(&dmabuf->attachments);
124 kds_resource_init(&dmabuf->kds);
128 EXPORT_SYMBOL_GPL(dma_buf_export);
132 * dma_buf_fd - returns a file descriptor for the given dma_buf
133 * @dmabuf: [in] pointer to dma_buf for which fd is required.
134 * @flags: [in] flags to give to fd
136 * On success, returns an associated 'fd'. Else, returns error.
138 int dma_buf_fd(struct dma_buf *dmabuf, int flags)
142 if (!dmabuf || !dmabuf->file)
145 error = get_unused_fd_flags(flags);
150 fd_install(fd, dmabuf->file);
154 EXPORT_SYMBOL_GPL(dma_buf_fd);
157 * dma_buf_get - returns the dma_buf structure related to an fd
158 * @fd: [in] fd associated with the dma_buf to be returned
160 * On success, returns the dma_buf structure associated with an fd; uses
161 * file's refcounting done by fget to increase refcount. returns ERR_PTR
164 struct dma_buf *dma_buf_get(int fd)
171 return ERR_PTR(-EBADF);
173 if (!is_dma_buf_file(file)) {
175 return ERR_PTR(-EINVAL);
178 return file->private_data;
180 EXPORT_SYMBOL_GPL(dma_buf_get);
183 * dma_buf_put - decreases refcount of the buffer
184 * @dmabuf: [in] buffer to reduce refcount of
186 * Uses file's refcounting done implicitly by fput()
188 void dma_buf_put(struct dma_buf *dmabuf)
190 if (WARN_ON(!dmabuf || !dmabuf->file))
195 EXPORT_SYMBOL_GPL(dma_buf_put);
198 * dma_buf_attach - Add the device to dma_buf's attachments list; optionally,
199 * calls attach() of dma_buf_ops to allow device-specific attach functionality
200 * @dmabuf: [in] buffer to attach device to.
201 * @dev: [in] device to be attached.
203 * Returns struct dma_buf_attachment * for this attachment; may return negative
207 struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,
210 struct dma_buf_attachment *attach;
213 if (WARN_ON(!dmabuf || !dev))
214 return ERR_PTR(-EINVAL);
216 attach = kzalloc(sizeof(struct dma_buf_attachment), GFP_KERNEL);
218 return ERR_PTR(-ENOMEM);
221 attach->dmabuf = dmabuf;
223 mutex_lock(&dmabuf->lock);
225 if (dmabuf->ops->attach) {
226 ret = dmabuf->ops->attach(dmabuf, dev, attach);
230 list_add(&attach->node, &dmabuf->attachments);
232 mutex_unlock(&dmabuf->lock);
237 mutex_unlock(&dmabuf->lock);
240 EXPORT_SYMBOL_GPL(dma_buf_attach);
243 * dma_buf_detach - Remove the given attachment from dmabuf's attachments list;
244 * optionally calls detach() of dma_buf_ops for device-specific detach
245 * @dmabuf: [in] buffer to detach from.
246 * @attach: [in] attachment to be detached; is free'd after this call.
249 void dma_buf_detach(struct dma_buf *dmabuf, struct dma_buf_attachment *attach)
251 if (WARN_ON(!dmabuf || !attach))
254 mutex_lock(&dmabuf->lock);
255 list_del(&attach->node);
256 if (dmabuf->ops->detach)
257 dmabuf->ops->detach(dmabuf, attach);
259 mutex_unlock(&dmabuf->lock);
262 EXPORT_SYMBOL_GPL(dma_buf_detach);
265 * dma_buf_map_attachment - Returns the scatterlist table of the attachment;
266 * mapped into _device_ address space. Is a wrapper for map_dma_buf() of the
268 * @attach: [in] attachment whose scatterlist is to be returned
269 * @direction: [in] direction of DMA transfer
271 * Returns sg_table containing the scatterlist to be returned; may return NULL
275 struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *attach,
276 enum dma_data_direction direction)
278 struct sg_table *sg_table = ERR_PTR(-EINVAL);
282 if (WARN_ON(!attach || !attach->dmabuf))
283 return ERR_PTR(-EINVAL);
285 sg_table = attach->dmabuf->ops->map_dma_buf(attach, direction);
289 EXPORT_SYMBOL_GPL(dma_buf_map_attachment);
292 * dma_buf_unmap_attachment - unmaps and decreases usecount of the buffer;might
293 * deallocate the scatterlist associated. Is a wrapper for unmap_dma_buf() of
295 * @attach: [in] attachment to unmap buffer from
296 * @sg_table: [in] scatterlist info of the buffer to unmap
297 * @direction: [in] direction of DMA transfer
300 void dma_buf_unmap_attachment(struct dma_buf_attachment *attach,
301 struct sg_table *sg_table,
302 enum dma_data_direction direction)
304 if (WARN_ON(!attach || !attach->dmabuf || !sg_table))
307 attach->dmabuf->ops->unmap_dma_buf(attach, sg_table,
310 EXPORT_SYMBOL_GPL(dma_buf_unmap_attachment);
314 * dma_buf_begin_cpu_access - Must be called before accessing a dma_buf from the
315 * cpu in the kernel context. Calls begin_cpu_access to allow exporter-specific
316 * preparations. Coherency is only guaranteed in the specified range for the
317 * specified access direction.
318 * @dma_buf: [in] buffer to prepare cpu access for.
319 * @start: [in] start of range for cpu access.
320 * @len: [in] length of range for cpu access.
321 * @direction: [in] length of range for cpu access.
323 * Can return negative error values, returns 0 on success.
325 int dma_buf_begin_cpu_access(struct dma_buf *dmabuf, size_t start, size_t len,
326 enum dma_data_direction direction)
330 if (WARN_ON(!dmabuf))
333 if (dmabuf->ops->begin_cpu_access)
334 ret = dmabuf->ops->begin_cpu_access(dmabuf, start, len, direction);
338 EXPORT_SYMBOL_GPL(dma_buf_begin_cpu_access);
341 * dma_buf_end_cpu_access - Must be called after accessing a dma_buf from the
342 * cpu in the kernel context. Calls end_cpu_access to allow exporter-specific
343 * actions. Coherency is only guaranteed in the specified range for the
344 * specified access direction.
345 * @dma_buf: [in] buffer to complete cpu access for.
346 * @start: [in] start of range for cpu access.
347 * @len: [in] length of range for cpu access.
348 * @direction: [in] length of range for cpu access.
350 * This call must always succeed.
352 void dma_buf_end_cpu_access(struct dma_buf *dmabuf, size_t start, size_t len,
353 enum dma_data_direction direction)
357 if (dmabuf->ops->end_cpu_access)
358 dmabuf->ops->end_cpu_access(dmabuf, start, len, direction);
360 EXPORT_SYMBOL_GPL(dma_buf_end_cpu_access);
363 * dma_buf_kmap_atomic - Map a page of the buffer object into kernel address
364 * space. The same restrictions as for kmap_atomic and friends apply.
365 * @dma_buf: [in] buffer to map page from.
366 * @page_num: [in] page in PAGE_SIZE units to map.
368 * This call must always succeed, any necessary preparations that might fail
369 * need to be done in begin_cpu_access.
371 void *dma_buf_kmap_atomic(struct dma_buf *dmabuf, unsigned long page_num)
375 return dmabuf->ops->kmap_atomic(dmabuf, page_num);
377 EXPORT_SYMBOL_GPL(dma_buf_kmap_atomic);
380 * dma_buf_kunmap_atomic - Unmap a page obtained by dma_buf_kmap_atomic.
381 * @dma_buf: [in] buffer to unmap page from.
382 * @page_num: [in] page in PAGE_SIZE units to unmap.
383 * @vaddr: [in] kernel space pointer obtained from dma_buf_kmap_atomic.
385 * This call must always succeed.
387 void dma_buf_kunmap_atomic(struct dma_buf *dmabuf, unsigned long page_num,
392 if (dmabuf->ops->kunmap_atomic)
393 dmabuf->ops->kunmap_atomic(dmabuf, page_num, vaddr);
395 EXPORT_SYMBOL_GPL(dma_buf_kunmap_atomic);
398 * dma_buf_kmap - Map a page of the buffer object into kernel address space. The
399 * same restrictions as for kmap and friends apply.
400 * @dma_buf: [in] buffer to map page from.
401 * @page_num: [in] page in PAGE_SIZE units to map.
403 * This call must always succeed, any necessary preparations that might fail
404 * need to be done in begin_cpu_access.
406 void *dma_buf_kmap(struct dma_buf *dmabuf, unsigned long page_num)
410 return dmabuf->ops->kmap(dmabuf, page_num);
412 EXPORT_SYMBOL_GPL(dma_buf_kmap);
415 * dma_buf_kunmap - Unmap a page obtained by dma_buf_kmap.
416 * @dma_buf: [in] buffer to unmap page from.
417 * @page_num: [in] page in PAGE_SIZE units to unmap.
418 * @vaddr: [in] kernel space pointer obtained from dma_buf_kmap.
420 * This call must always succeed.
422 void dma_buf_kunmap(struct dma_buf *dmabuf, unsigned long page_num,
427 if (dmabuf->ops->kunmap)
428 dmabuf->ops->kunmap(dmabuf, page_num, vaddr);
430 EXPORT_SYMBOL_GPL(dma_buf_kunmap);
434 * dma_buf_mmap - Setup up a userspace mmap with the given vma
435 * @dmabuf: [in] buffer that should back the vma
436 * @vma: [in] vma for the mmap
437 * @pgoff: [in] offset in pages where this mmap should start within the
440 * This function adjusts the passed in vma so that it points at the file of the
441 * dma_buf operation. It alsog adjusts the starting pgoff and does bounds
442 * checking on the size of the vma. Then it calls the exporters mmap function to
443 * set up the mapping.
445 * Can return negative error values, returns 0 on success.
447 int dma_buf_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma,
450 if (WARN_ON(!dmabuf || !vma))
453 /* check for offset overflow */
454 if (pgoff + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) < pgoff)
457 /* check for overflowing the buffer's size */
458 if (pgoff + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) >
459 dmabuf->size >> PAGE_SHIFT)
462 /* readjust the vma */
466 vma->vm_file = dmabuf->file;
467 get_file(vma->vm_file);
469 vma->vm_pgoff = pgoff;
471 return dmabuf->ops->mmap(dmabuf, vma);
473 EXPORT_SYMBOL_GPL(dma_buf_mmap);
476 * dma_buf_vmap - Create virtual mapping for the buffer object into kernel
477 * address space. Same restrictions as for vmap and friends apply.
478 * @dmabuf: [in] buffer to vmap
480 * This call may fail due to lack of virtual mapping address space.
481 * These calls are optional in drivers. The intended use for them
482 * is for mapping objects linear in kernel space for high use objects.
483 * Please attempt to use kmap/kunmap before thinking about these interfaces.
485 void *dma_buf_vmap(struct dma_buf *dmabuf)
487 if (WARN_ON(!dmabuf))
490 if (dmabuf->ops->vmap)
491 return dmabuf->ops->vmap(dmabuf);
494 EXPORT_SYMBOL_GPL(dma_buf_vmap);
497 * dma_buf_vunmap - Unmap a vmap obtained by dma_buf_vmap.
498 * @dmabuf: [in] buffer to vunmap
500 void dma_buf_vunmap(struct dma_buf *dmabuf, void *vaddr)
502 if (WARN_ON(!dmabuf))
505 if (dmabuf->ops->vunmap)
506 dmabuf->ops->vunmap(dmabuf, vaddr);
508 EXPORT_SYMBOL_GPL(dma_buf_vunmap);