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 #ifdef CONFIG_DMA_SHARED_BUFFER_USES_KDS
44 kds_resource_term(&dmabuf->kds);
50 static int dma_buf_mmap_internal(struct file *file, struct vm_area_struct *vma)
52 struct dma_buf *dmabuf;
54 if (!is_dma_buf_file(file))
57 dmabuf = file->private_data;
59 /* check for overflowing the buffer's size */
60 if (vma->vm_pgoff + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) >
61 dmabuf->size >> PAGE_SHIFT)
64 return dmabuf->ops->mmap(dmabuf, vma);
67 static const struct file_operations dma_buf_fops = {
68 .release = dma_buf_release,
69 .mmap = dma_buf_mmap_internal,
73 * is_dma_buf_file - Check if struct file* is associated with dma_buf
75 static inline int is_dma_buf_file(struct file *file)
77 return file->f_op == &dma_buf_fops;
81 * dma_buf_export - Creates a new dma_buf, and associates an anon file
82 * with this buffer, so it can be exported.
83 * Also connect the allocator specific data and ops to the buffer.
85 * @priv: [in] Attach private data of allocator to this buffer
86 * @ops: [in] Attach allocator-defined dma buf ops to the new buffer.
87 * @size: [in] Size of the buffer
88 * @flags: [in] mode flags for the file.
90 * Returns, on success, a newly created dma_buf object, which wraps the
91 * supplied private data and operations for dma_buf_ops. On either missing
92 * ops, or error in allocating struct dma_buf, will return negative error.
95 struct dma_buf *dma_buf_export(void *priv, const struct dma_buf_ops *ops,
96 size_t size, int flags)
98 struct dma_buf *dmabuf;
101 if (WARN_ON(!priv || !ops
103 || !ops->unmap_dma_buf
108 return ERR_PTR(-EINVAL);
111 dmabuf = kzalloc(sizeof(struct dma_buf), GFP_KERNEL);
113 return ERR_PTR(-ENOMEM);
119 file = anon_inode_getfile("dmabuf", &dma_buf_fops, dmabuf, flags);
123 mutex_init(&dmabuf->lock);
124 INIT_LIST_HEAD(&dmabuf->attachments);
126 #ifdef CONFIG_DMA_SHARED_BUFFER_USES_KDS
127 kds_resource_init(&dmabuf->kds);
132 EXPORT_SYMBOL_GPL(dma_buf_export);
136 * dma_buf_fd - returns a file descriptor for the given dma_buf
137 * @dmabuf: [in] pointer to dma_buf for which fd is required.
138 * @flags: [in] flags to give to fd
140 * On success, returns an associated 'fd'. Else, returns error.
142 int dma_buf_fd(struct dma_buf *dmabuf, int flags)
146 if (!dmabuf || !dmabuf->file)
149 error = get_unused_fd_flags(flags);
154 fd_install(fd, dmabuf->file);
158 EXPORT_SYMBOL_GPL(dma_buf_fd);
161 * dma_buf_get - returns the dma_buf structure related to an fd
162 * @fd: [in] fd associated with the dma_buf to be returned
164 * On success, returns the dma_buf structure associated with an fd; uses
165 * file's refcounting done by fget to increase refcount. returns ERR_PTR
168 struct dma_buf *dma_buf_get(int fd)
175 return ERR_PTR(-EBADF);
177 if (!is_dma_buf_file(file)) {
179 return ERR_PTR(-EINVAL);
182 return file->private_data;
184 EXPORT_SYMBOL_GPL(dma_buf_get);
187 * dma_buf_put - decreases refcount of the buffer
188 * @dmabuf: [in] buffer to reduce refcount of
190 * Uses file's refcounting done implicitly by fput()
192 void dma_buf_put(struct dma_buf *dmabuf)
194 if (WARN_ON(!dmabuf || !dmabuf->file))
199 EXPORT_SYMBOL_GPL(dma_buf_put);
202 * dma_buf_attach - Add the device to dma_buf's attachments list; optionally,
203 * calls attach() of dma_buf_ops to allow device-specific attach functionality
204 * @dmabuf: [in] buffer to attach device to.
205 * @dev: [in] device to be attached.
207 * Returns struct dma_buf_attachment * for this attachment; may return negative
211 struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,
214 struct dma_buf_attachment *attach;
217 if (WARN_ON(!dmabuf || !dev))
218 return ERR_PTR(-EINVAL);
220 attach = kzalloc(sizeof(struct dma_buf_attachment), GFP_KERNEL);
222 return ERR_PTR(-ENOMEM);
225 attach->dmabuf = dmabuf;
227 mutex_lock(&dmabuf->lock);
229 if (dmabuf->ops->attach) {
230 ret = dmabuf->ops->attach(dmabuf, dev, attach);
234 list_add(&attach->node, &dmabuf->attachments);
236 mutex_unlock(&dmabuf->lock);
241 mutex_unlock(&dmabuf->lock);
244 EXPORT_SYMBOL_GPL(dma_buf_attach);
247 * dma_buf_detach - Remove the given attachment from dmabuf's attachments list;
248 * optionally calls detach() of dma_buf_ops for device-specific detach
249 * @dmabuf: [in] buffer to detach from.
250 * @attach: [in] attachment to be detached; is free'd after this call.
253 void dma_buf_detach(struct dma_buf *dmabuf, struct dma_buf_attachment *attach)
255 if (WARN_ON(!dmabuf || !attach))
258 mutex_lock(&dmabuf->lock);
259 list_del(&attach->node);
260 if (dmabuf->ops->detach)
261 dmabuf->ops->detach(dmabuf, attach);
263 mutex_unlock(&dmabuf->lock);
266 EXPORT_SYMBOL_GPL(dma_buf_detach);
269 * dma_buf_map_attachment - Returns the scatterlist table of the attachment;
270 * mapped into _device_ address space. Is a wrapper for map_dma_buf() of the
272 * @attach: [in] attachment whose scatterlist is to be returned
273 * @direction: [in] direction of DMA transfer
275 * Returns sg_table containing the scatterlist to be returned; may return NULL
279 struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *attach,
280 enum dma_data_direction direction)
282 struct sg_table *sg_table = ERR_PTR(-EINVAL);
286 if (WARN_ON(!attach || !attach->dmabuf))
287 return ERR_PTR(-EINVAL);
289 sg_table = attach->dmabuf->ops->map_dma_buf(attach, direction);
293 EXPORT_SYMBOL_GPL(dma_buf_map_attachment);
296 * dma_buf_unmap_attachment - unmaps and decreases usecount of the buffer;might
297 * deallocate the scatterlist associated. Is a wrapper for unmap_dma_buf() of
299 * @attach: [in] attachment to unmap buffer from
300 * @sg_table: [in] scatterlist info of the buffer to unmap
301 * @direction: [in] direction of DMA transfer
304 void dma_buf_unmap_attachment(struct dma_buf_attachment *attach,
305 struct sg_table *sg_table,
306 enum dma_data_direction direction)
308 if (WARN_ON(!attach || !attach->dmabuf || !sg_table))
311 attach->dmabuf->ops->unmap_dma_buf(attach, sg_table,
314 EXPORT_SYMBOL_GPL(dma_buf_unmap_attachment);
318 * dma_buf_begin_cpu_access - Must be called before accessing a dma_buf from the
319 * cpu in the kernel context. Calls begin_cpu_access to allow exporter-specific
320 * preparations. Coherency is only guaranteed in the specified range for the
321 * specified access direction.
322 * @dma_buf: [in] buffer to prepare cpu access for.
323 * @start: [in] start of range for cpu access.
324 * @len: [in] length of range for cpu access.
325 * @direction: [in] length of range for cpu access.
327 * Can return negative error values, returns 0 on success.
329 int dma_buf_begin_cpu_access(struct dma_buf *dmabuf, size_t start, size_t len,
330 enum dma_data_direction direction)
334 if (WARN_ON(!dmabuf))
337 if (dmabuf->ops->begin_cpu_access)
338 ret = dmabuf->ops->begin_cpu_access(dmabuf, start, len, direction);
342 EXPORT_SYMBOL_GPL(dma_buf_begin_cpu_access);
345 * dma_buf_end_cpu_access - Must be called after accessing a dma_buf from the
346 * cpu in the kernel context. Calls end_cpu_access to allow exporter-specific
347 * actions. Coherency is only guaranteed in the specified range for the
348 * specified access direction.
349 * @dma_buf: [in] buffer to complete cpu access for.
350 * @start: [in] start of range for cpu access.
351 * @len: [in] length of range for cpu access.
352 * @direction: [in] length of range for cpu access.
354 * This call must always succeed.
356 void dma_buf_end_cpu_access(struct dma_buf *dmabuf, size_t start, size_t len,
357 enum dma_data_direction direction)
361 if (dmabuf->ops->end_cpu_access)
362 dmabuf->ops->end_cpu_access(dmabuf, start, len, direction);
364 EXPORT_SYMBOL_GPL(dma_buf_end_cpu_access);
367 * dma_buf_kmap_atomic - Map a page of the buffer object into kernel address
368 * space. The same restrictions as for kmap_atomic and friends apply.
369 * @dma_buf: [in] buffer to map page from.
370 * @page_num: [in] page in PAGE_SIZE units to map.
372 * This call must always succeed, any necessary preparations that might fail
373 * need to be done in begin_cpu_access.
375 void *dma_buf_kmap_atomic(struct dma_buf *dmabuf, unsigned long page_num)
379 return dmabuf->ops->kmap_atomic(dmabuf, page_num);
381 EXPORT_SYMBOL_GPL(dma_buf_kmap_atomic);
384 * dma_buf_kunmap_atomic - Unmap a page obtained by dma_buf_kmap_atomic.
385 * @dma_buf: [in] buffer to unmap page from.
386 * @page_num: [in] page in PAGE_SIZE units to unmap.
387 * @vaddr: [in] kernel space pointer obtained from dma_buf_kmap_atomic.
389 * This call must always succeed.
391 void dma_buf_kunmap_atomic(struct dma_buf *dmabuf, unsigned long page_num,
396 if (dmabuf->ops->kunmap_atomic)
397 dmabuf->ops->kunmap_atomic(dmabuf, page_num, vaddr);
399 EXPORT_SYMBOL_GPL(dma_buf_kunmap_atomic);
402 * dma_buf_kmap - Map a page of the buffer object into kernel address space. The
403 * same restrictions as for kmap and friends apply.
404 * @dma_buf: [in] buffer to map page from.
405 * @page_num: [in] page in PAGE_SIZE units to map.
407 * This call must always succeed, any necessary preparations that might fail
408 * need to be done in begin_cpu_access.
410 void *dma_buf_kmap(struct dma_buf *dmabuf, unsigned long page_num)
414 return dmabuf->ops->kmap(dmabuf, page_num);
416 EXPORT_SYMBOL_GPL(dma_buf_kmap);
419 * dma_buf_kunmap - Unmap a page obtained by dma_buf_kmap.
420 * @dma_buf: [in] buffer to unmap page from.
421 * @page_num: [in] page in PAGE_SIZE units to unmap.
422 * @vaddr: [in] kernel space pointer obtained from dma_buf_kmap.
424 * This call must always succeed.
426 void dma_buf_kunmap(struct dma_buf *dmabuf, unsigned long page_num,
431 if (dmabuf->ops->kunmap)
432 dmabuf->ops->kunmap(dmabuf, page_num, vaddr);
434 EXPORT_SYMBOL_GPL(dma_buf_kunmap);
438 * dma_buf_mmap - Setup up a userspace mmap with the given vma
439 * @dmabuf: [in] buffer that should back the vma
440 * @vma: [in] vma for the mmap
441 * @pgoff: [in] offset in pages where this mmap should start within the
444 * This function adjusts the passed in vma so that it points at the file of the
445 * dma_buf operation. It alsog adjusts the starting pgoff and does bounds
446 * checking on the size of the vma. Then it calls the exporters mmap function to
447 * set up the mapping.
449 * Can return negative error values, returns 0 on success.
451 int dma_buf_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma,
454 struct file *oldfile;
457 if (WARN_ON(!dmabuf || !vma))
460 /* check for offset overflow */
461 if (pgoff + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) < pgoff)
464 /* check for overflowing the buffer's size */
465 if (pgoff + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) >
466 dmabuf->size >> PAGE_SHIFT)
469 /* readjust the vma */
470 get_file(dmabuf->file);
471 oldfile = vma->vm_file;
472 vma->vm_file = dmabuf->file;
473 vma->vm_pgoff = pgoff;
475 ret = dmabuf->ops->mmap(dmabuf, vma);
477 /* restore old parameters on failure */
478 vma->vm_file = oldfile;
486 EXPORT_SYMBOL_GPL(dma_buf_mmap);
489 * dma_buf_vmap - Create virtual mapping for the buffer object into kernel
490 * address space. Same restrictions as for vmap and friends apply.
491 * @dmabuf: [in] buffer to vmap
493 * This call may fail due to lack of virtual mapping address space.
494 * These calls are optional in drivers. The intended use for them
495 * is for mapping objects linear in kernel space for high use objects.
496 * Please attempt to use kmap/kunmap before thinking about these interfaces.
498 void *dma_buf_vmap(struct dma_buf *dmabuf)
500 if (WARN_ON(!dmabuf))
503 if (dmabuf->ops->vmap)
504 return dmabuf->ops->vmap(dmabuf);
507 EXPORT_SYMBOL_GPL(dma_buf_vmap);
510 * dma_buf_vunmap - Unmap a vmap obtained by dma_buf_vmap.
511 * @dmabuf: [in] buffer to vunmap
513 void dma_buf_vunmap(struct dma_buf *dmabuf, void *vaddr)
515 if (WARN_ON(!dmabuf))
518 if (dmabuf->ops->vunmap)
519 dmabuf->ops->vunmap(dmabuf, vaddr);
521 EXPORT_SYMBOL_GPL(dma_buf_vunmap);