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>
30 #include <linux/poll.h>
31 #include <linux/sched.h>
33 static inline int is_dma_buf_file(struct file *);
35 static int dma_buf_release(struct inode *inode, struct file *file)
37 struct dma_buf *dmabuf;
39 if (!is_dma_buf_file(file))
42 dmabuf = file->private_data;
44 dmabuf->ops->release(dmabuf);
45 kds_callback_term(&dmabuf->kds_cb);
46 kds_resource_term(&dmabuf->kds);
51 static int dma_buf_mmap_internal(struct file *file, struct vm_area_struct *vma)
53 struct dma_buf *dmabuf;
55 if (!is_dma_buf_file(file))
58 dmabuf = file->private_data;
60 /* check for overflowing the buffer's size */
61 if (vma->vm_pgoff + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) >
62 dmabuf->size >> PAGE_SHIFT)
65 return dmabuf->ops->mmap(dmabuf, vma);
69 static void dma_buf_kds_cb_fn(void *param1, void *param2)
71 struct kds_resource_set **rset_ptr = param1;
72 struct kds_resource_set *rset = *rset_ptr;
73 wait_queue_head_t *wait_queue = param2;
76 kds_resource_set_release(&rset);
80 static int dma_buf_kds_check(struct kds_resource *kds,
81 unsigned long exclusive, int *poll_ret)
83 /* Synchronous wait with 0 timeout - poll availability */
84 struct kds_resource_set *rset = kds_waitall(1, &exclusive, &kds, 0);
90 kds_resource_set_release(&rset);
91 *poll_ret = POLLIN | POLLRDNORM;
93 *poll_ret |= POLLOUT | POLLWRNORM;
100 static unsigned int dma_buf_poll(struct file *file,
101 struct poll_table_struct *wait)
103 struct dma_buf *dmabuf;
104 struct kds_resource *kds;
105 unsigned int ret = 0;
107 if (!is_dma_buf_file(file))
110 dmabuf = file->private_data;
113 if (poll_does_not_wait(wait)) {
114 /* Check for exclusive access (superset of shared) first */
115 if (!dma_buf_kds_check(kds, 1ul, &ret))
116 dma_buf_kds_check(kds, 0ul, &ret);
118 int events = poll_requested_events(wait);
119 unsigned long exclusive;
120 wait_queue_head_t *wq;
121 struct kds_resource_set **rset_ptr =
122 kmalloc(sizeof(*rset_ptr), GFP_KERNEL);
127 if (events & POLLOUT) {
128 wq = &dmabuf->wq_exclusive;
131 wq = &dmabuf->wq_shared;
134 poll_wait(file, wq, wait);
135 ret = kds_async_waitall(rset_ptr, KDS_FLAG_LOCKED_WAIT,
136 &dmabuf->kds_cb, rset_ptr, wq, 1, &exclusive,
139 if (IS_ERR_VALUE(ret)) {
143 /* Can't allow access until callback */
150 static const struct file_operations dma_buf_fops = {
151 .release = dma_buf_release,
152 .mmap = dma_buf_mmap_internal,
153 .poll = dma_buf_poll,
157 * is_dma_buf_file - Check if struct file* is associated with dma_buf
159 static inline int is_dma_buf_file(struct file *file)
161 return file->f_op == &dma_buf_fops;
165 * dma_buf_export - Creates a new dma_buf, and associates an anon file
166 * with this buffer, so it can be exported.
167 * Also connect the allocator specific data and ops to the buffer.
169 * @priv: [in] Attach private data of allocator to this buffer
170 * @ops: [in] Attach allocator-defined dma buf ops to the new buffer.
171 * @size: [in] Size of the buffer
172 * @flags: [in] mode flags for the file.
174 * Returns, on success, a newly created dma_buf object, which wraps the
175 * supplied private data and operations for dma_buf_ops. On either missing
176 * ops, or error in allocating struct dma_buf, will return negative error.
179 struct dma_buf *dma_buf_export(void *priv, const struct dma_buf_ops *ops,
180 size_t size, int flags)
182 struct dma_buf *dmabuf;
185 if (WARN_ON(!priv || !ops
187 || !ops->unmap_dma_buf
192 return ERR_PTR(-EINVAL);
195 dmabuf = kzalloc(sizeof(struct dma_buf), GFP_KERNEL);
197 return ERR_PTR(-ENOMEM);
203 file = anon_inode_getfile("dmabuf", &dma_buf_fops, dmabuf, flags);
207 mutex_init(&dmabuf->lock);
208 INIT_LIST_HEAD(&dmabuf->attachments);
210 init_waitqueue_head(&dmabuf->wq_exclusive);
211 init_waitqueue_head(&dmabuf->wq_shared);
212 kds_resource_init(&dmabuf->kds);
213 kds_callback_init(&dmabuf->kds_cb, 1, dma_buf_kds_cb_fn);
217 EXPORT_SYMBOL_GPL(dma_buf_export);
221 * dma_buf_fd - returns a file descriptor for the given dma_buf
222 * @dmabuf: [in] pointer to dma_buf for which fd is required.
223 * @flags: [in] flags to give to fd
225 * On success, returns an associated 'fd'. Else, returns error.
227 int dma_buf_fd(struct dma_buf *dmabuf, int flags)
231 if (!dmabuf || !dmabuf->file)
234 error = get_unused_fd_flags(flags);
239 fd_install(fd, dmabuf->file);
243 EXPORT_SYMBOL_GPL(dma_buf_fd);
246 * dma_buf_get - returns the dma_buf structure related to an fd
247 * @fd: [in] fd associated with the dma_buf to be returned
249 * On success, returns the dma_buf structure associated with an fd; uses
250 * file's refcounting done by fget to increase refcount. returns ERR_PTR
253 struct dma_buf *dma_buf_get(int fd)
260 return ERR_PTR(-EBADF);
262 if (!is_dma_buf_file(file)) {
264 return ERR_PTR(-EINVAL);
267 return file->private_data;
269 EXPORT_SYMBOL_GPL(dma_buf_get);
272 * dma_buf_put - decreases refcount of the buffer
273 * @dmabuf: [in] buffer to reduce refcount of
275 * Uses file's refcounting done implicitly by fput()
277 void dma_buf_put(struct dma_buf *dmabuf)
279 if (WARN_ON(!dmabuf || !dmabuf->file))
284 EXPORT_SYMBOL_GPL(dma_buf_put);
287 * dma_buf_attach - Add the device to dma_buf's attachments list; optionally,
288 * calls attach() of dma_buf_ops to allow device-specific attach functionality
289 * @dmabuf: [in] buffer to attach device to.
290 * @dev: [in] device to be attached.
292 * Returns struct dma_buf_attachment * for this attachment; may return negative
296 struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,
299 struct dma_buf_attachment *attach;
302 if (WARN_ON(!dmabuf || !dev))
303 return ERR_PTR(-EINVAL);
305 attach = kzalloc(sizeof(struct dma_buf_attachment), GFP_KERNEL);
307 return ERR_PTR(-ENOMEM);
310 attach->dmabuf = dmabuf;
312 mutex_lock(&dmabuf->lock);
314 if (dmabuf->ops->attach) {
315 ret = dmabuf->ops->attach(dmabuf, dev, attach);
319 list_add(&attach->node, &dmabuf->attachments);
321 mutex_unlock(&dmabuf->lock);
326 mutex_unlock(&dmabuf->lock);
329 EXPORT_SYMBOL_GPL(dma_buf_attach);
332 * dma_buf_detach - Remove the given attachment from dmabuf's attachments list;
333 * optionally calls detach() of dma_buf_ops for device-specific detach
334 * @dmabuf: [in] buffer to detach from.
335 * @attach: [in] attachment to be detached; is free'd after this call.
338 void dma_buf_detach(struct dma_buf *dmabuf, struct dma_buf_attachment *attach)
340 if (WARN_ON(!dmabuf || !attach))
343 mutex_lock(&dmabuf->lock);
344 list_del(&attach->node);
345 if (dmabuf->ops->detach)
346 dmabuf->ops->detach(dmabuf, attach);
348 mutex_unlock(&dmabuf->lock);
351 EXPORT_SYMBOL_GPL(dma_buf_detach);
354 * dma_buf_map_attachment - Returns the scatterlist table of the attachment;
355 * mapped into _device_ address space. Is a wrapper for map_dma_buf() of the
357 * @attach: [in] attachment whose scatterlist is to be returned
358 * @direction: [in] direction of DMA transfer
360 * Returns sg_table containing the scatterlist to be returned; may return NULL
364 struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *attach,
365 enum dma_data_direction direction)
367 struct sg_table *sg_table = ERR_PTR(-EINVAL);
371 if (WARN_ON(!attach || !attach->dmabuf))
372 return ERR_PTR(-EINVAL);
374 sg_table = attach->dmabuf->ops->map_dma_buf(attach, direction);
378 EXPORT_SYMBOL_GPL(dma_buf_map_attachment);
381 * dma_buf_unmap_attachment - unmaps and decreases usecount of the buffer;might
382 * deallocate the scatterlist associated. Is a wrapper for unmap_dma_buf() of
384 * @attach: [in] attachment to unmap buffer from
385 * @sg_table: [in] scatterlist info of the buffer to unmap
386 * @direction: [in] direction of DMA transfer
389 void dma_buf_unmap_attachment(struct dma_buf_attachment *attach,
390 struct sg_table *sg_table,
391 enum dma_data_direction direction)
393 if (WARN_ON(!attach || !attach->dmabuf || !sg_table))
396 attach->dmabuf->ops->unmap_dma_buf(attach, sg_table,
399 EXPORT_SYMBOL_GPL(dma_buf_unmap_attachment);
403 * dma_buf_begin_cpu_access - Must be called before accessing a dma_buf from the
404 * cpu in the kernel context. Calls begin_cpu_access to allow exporter-specific
405 * preparations. Coherency is only guaranteed in the specified range for the
406 * specified access direction.
407 * @dma_buf: [in] buffer to prepare cpu access for.
408 * @start: [in] start of range for cpu access.
409 * @len: [in] length of range for cpu access.
410 * @direction: [in] length of range for cpu access.
412 * Can return negative error values, returns 0 on success.
414 int dma_buf_begin_cpu_access(struct dma_buf *dmabuf, size_t start, size_t len,
415 enum dma_data_direction direction)
419 if (WARN_ON(!dmabuf))
422 if (dmabuf->ops->begin_cpu_access)
423 ret = dmabuf->ops->begin_cpu_access(dmabuf, start, len, direction);
427 EXPORT_SYMBOL_GPL(dma_buf_begin_cpu_access);
430 * dma_buf_end_cpu_access - Must be called after accessing a dma_buf from the
431 * cpu in the kernel context. Calls end_cpu_access to allow exporter-specific
432 * actions. Coherency is only guaranteed in the specified range for the
433 * specified access direction.
434 * @dma_buf: [in] buffer to complete cpu access for.
435 * @start: [in] start of range for cpu access.
436 * @len: [in] length of range for cpu access.
437 * @direction: [in] length of range for cpu access.
439 * This call must always succeed.
441 void dma_buf_end_cpu_access(struct dma_buf *dmabuf, size_t start, size_t len,
442 enum dma_data_direction direction)
446 if (dmabuf->ops->end_cpu_access)
447 dmabuf->ops->end_cpu_access(dmabuf, start, len, direction);
449 EXPORT_SYMBOL_GPL(dma_buf_end_cpu_access);
452 * dma_buf_kmap_atomic - Map a page of the buffer object into kernel address
453 * space. The same restrictions as for kmap_atomic and friends apply.
454 * @dma_buf: [in] buffer to map page from.
455 * @page_num: [in] page in PAGE_SIZE units to map.
457 * This call must always succeed, any necessary preparations that might fail
458 * need to be done in begin_cpu_access.
460 void *dma_buf_kmap_atomic(struct dma_buf *dmabuf, unsigned long page_num)
464 return dmabuf->ops->kmap_atomic(dmabuf, page_num);
466 EXPORT_SYMBOL_GPL(dma_buf_kmap_atomic);
469 * dma_buf_kunmap_atomic - Unmap a page obtained by dma_buf_kmap_atomic.
470 * @dma_buf: [in] buffer to unmap page from.
471 * @page_num: [in] page in PAGE_SIZE units to unmap.
472 * @vaddr: [in] kernel space pointer obtained from dma_buf_kmap_atomic.
474 * This call must always succeed.
476 void dma_buf_kunmap_atomic(struct dma_buf *dmabuf, unsigned long page_num,
481 if (dmabuf->ops->kunmap_atomic)
482 dmabuf->ops->kunmap_atomic(dmabuf, page_num, vaddr);
484 EXPORT_SYMBOL_GPL(dma_buf_kunmap_atomic);
487 * dma_buf_kmap - Map a page of the buffer object into kernel address space. The
488 * same restrictions as for kmap and friends apply.
489 * @dma_buf: [in] buffer to map page from.
490 * @page_num: [in] page in PAGE_SIZE units to map.
492 * This call must always succeed, any necessary preparations that might fail
493 * need to be done in begin_cpu_access.
495 void *dma_buf_kmap(struct dma_buf *dmabuf, unsigned long page_num)
499 return dmabuf->ops->kmap(dmabuf, page_num);
501 EXPORT_SYMBOL_GPL(dma_buf_kmap);
504 * dma_buf_kunmap - Unmap a page obtained by dma_buf_kmap.
505 * @dma_buf: [in] buffer to unmap page from.
506 * @page_num: [in] page in PAGE_SIZE units to unmap.
507 * @vaddr: [in] kernel space pointer obtained from dma_buf_kmap.
509 * This call must always succeed.
511 void dma_buf_kunmap(struct dma_buf *dmabuf, unsigned long page_num,
516 if (dmabuf->ops->kunmap)
517 dmabuf->ops->kunmap(dmabuf, page_num, vaddr);
519 EXPORT_SYMBOL_GPL(dma_buf_kunmap);
523 * dma_buf_mmap - Setup up a userspace mmap with the given vma
524 * @dmabuf: [in] buffer that should back the vma
525 * @vma: [in] vma for the mmap
526 * @pgoff: [in] offset in pages where this mmap should start within the
529 * This function adjusts the passed in vma so that it points at the file of the
530 * dma_buf operation. It alsog adjusts the starting pgoff and does bounds
531 * checking on the size of the vma. Then it calls the exporters mmap function to
532 * set up the mapping.
534 * Can return negative error values, returns 0 on success.
536 int dma_buf_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma,
539 struct file *oldfile;
542 if (WARN_ON(!dmabuf || !vma))
545 /* check for offset overflow */
546 if (pgoff + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) < pgoff)
549 /* check for overflowing the buffer's size */
550 if (pgoff + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) >
551 dmabuf->size >> PAGE_SHIFT)
554 /* readjust the vma */
555 get_file(dmabuf->file);
556 oldfile = vma->vm_file;
557 vma->vm_file = dmabuf->file;
558 vma->vm_pgoff = pgoff;
560 ret = dmabuf->ops->mmap(dmabuf, vma);
562 /* restore old parameters on failure */
563 vma->vm_file = oldfile;
571 EXPORT_SYMBOL_GPL(dma_buf_mmap);
574 * dma_buf_vmap - Create virtual mapping for the buffer object into kernel
575 * address space. Same restrictions as for vmap and friends apply.
576 * @dmabuf: [in] buffer to vmap
578 * This call may fail due to lack of virtual mapping address space.
579 * These calls are optional in drivers. The intended use for them
580 * is for mapping objects linear in kernel space for high use objects.
581 * Please attempt to use kmap/kunmap before thinking about these interfaces.
583 void *dma_buf_vmap(struct dma_buf *dmabuf)
585 if (WARN_ON(!dmabuf))
588 if (dmabuf->ops->vmap)
589 return dmabuf->ops->vmap(dmabuf);
592 EXPORT_SYMBOL_GPL(dma_buf_vmap);
595 * dma_buf_vunmap - Unmap a vmap obtained by dma_buf_vmap.
596 * @dmabuf: [in] buffer to vunmap
598 void dma_buf_vunmap(struct dma_buf *dmabuf, void *vaddr)
600 if (WARN_ON(!dmabuf))
603 if (dmabuf->ops->vunmap)
604 dmabuf->ops->vunmap(dmabuf, vaddr);
606 EXPORT_SYMBOL_GPL(dma_buf_vunmap);