Root/drivers/base/dma-buf.c

1/*
2 * Framework for buffer objects that can be shared across devices/subsystems.
3 *
4 * Copyright(C) 2011 Linaro Limited. All rights reserved.
5 * Author: Sumit Semwal <sumit.semwal@ti.com>
6 *
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.
11 *
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.
15 *
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
19 * more details.
20 *
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/>.
23 */
24
25#include <linux/fs.h>
26#include <linux/slab.h>
27#include <linux/dma-buf.h>
28#include <linux/anon_inodes.h>
29#include <linux/export.h>
30
31static inline int is_dma_buf_file(struct file *);
32
33static int dma_buf_release(struct inode *inode, struct file *file)
34{
35    struct dma_buf *dmabuf;
36
37    if (!is_dma_buf_file(file))
38        return -EINVAL;
39
40    dmabuf = file->private_data;
41
42    BUG_ON(dmabuf->vmapping_counter);
43
44    dmabuf->ops->release(dmabuf);
45    kfree(dmabuf);
46    return 0;
47}
48
49static int dma_buf_mmap_internal(struct file *file, struct vm_area_struct *vma)
50{
51    struct dma_buf *dmabuf;
52
53    if (!is_dma_buf_file(file))
54        return -EINVAL;
55
56    dmabuf = file->private_data;
57
58    /* check for overflowing the buffer's size */
59    if (vma->vm_pgoff + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) >
60        dmabuf->size >> PAGE_SHIFT)
61        return -EINVAL;
62
63    return dmabuf->ops->mmap(dmabuf, vma);
64}
65
66static const struct file_operations dma_buf_fops = {
67    .release = dma_buf_release,
68    .mmap = dma_buf_mmap_internal,
69};
70
71/*
72 * is_dma_buf_file - Check if struct file* is associated with dma_buf
73 */
74static inline int is_dma_buf_file(struct file *file)
75{
76    return file->f_op == &dma_buf_fops;
77}
78
79/**
80 * dma_buf_export - Creates a new dma_buf, and associates an anon file
81 * with this buffer, so it can be exported.
82 * Also connect the allocator specific data and ops to the buffer.
83 *
84 * @priv: [in] Attach private data of allocator to this buffer
85 * @ops: [in] Attach allocator-defined dma buf ops to the new buffer.
86 * @size: [in] Size of the buffer
87 * @flags: [in] mode flags for the file.
88 *
89 * Returns, on success, a newly created dma_buf object, which wraps the
90 * supplied private data and operations for dma_buf_ops. On either missing
91 * ops, or error in allocating struct dma_buf, will return negative error.
92 *
93 */
94struct dma_buf *dma_buf_export(void *priv, const struct dma_buf_ops *ops,
95                size_t size, int flags)
96{
97    struct dma_buf *dmabuf;
98    struct file *file;
99
100    if (WARN_ON(!priv || !ops
101              || !ops->map_dma_buf
102              || !ops->unmap_dma_buf
103              || !ops->release
104              || !ops->kmap_atomic
105              || !ops->kmap
106              || !ops->mmap)) {
107        return ERR_PTR(-EINVAL);
108    }
109
110    dmabuf = kzalloc(sizeof(struct dma_buf), GFP_KERNEL);
111    if (dmabuf == NULL)
112        return ERR_PTR(-ENOMEM);
113
114    dmabuf->priv = priv;
115    dmabuf->ops = ops;
116    dmabuf->size = size;
117
118    file = anon_inode_getfile("dmabuf", &dma_buf_fops, dmabuf, flags);
119
120    dmabuf->file = file;
121
122    mutex_init(&dmabuf->lock);
123    INIT_LIST_HEAD(&dmabuf->attachments);
124
125    return dmabuf;
126}
127EXPORT_SYMBOL_GPL(dma_buf_export);
128
129
130/**
131 * dma_buf_fd - returns a file descriptor for the given dma_buf
132 * @dmabuf: [in] pointer to dma_buf for which fd is required.
133 * @flags: [in] flags to give to fd
134 *
135 * On success, returns an associated 'fd'. Else, returns error.
136 */
137int dma_buf_fd(struct dma_buf *dmabuf, int flags)
138{
139    int fd;
140
141    if (!dmabuf || !dmabuf->file)
142        return -EINVAL;
143
144    fd = get_unused_fd_flags(flags);
145    if (fd < 0)
146        return fd;
147
148    fd_install(fd, dmabuf->file);
149
150    return fd;
151}
152EXPORT_SYMBOL_GPL(dma_buf_fd);
153
154/**
155 * dma_buf_get - returns the dma_buf structure related to an fd
156 * @fd: [in] fd associated with the dma_buf to be returned
157 *
158 * On success, returns the dma_buf structure associated with an fd; uses
159 * file's refcounting done by fget to increase refcount. returns ERR_PTR
160 * otherwise.
161 */
162struct dma_buf *dma_buf_get(int fd)
163{
164    struct file *file;
165
166    file = fget(fd);
167
168    if (!file)
169        return ERR_PTR(-EBADF);
170
171    if (!is_dma_buf_file(file)) {
172        fput(file);
173        return ERR_PTR(-EINVAL);
174    }
175
176    return file->private_data;
177}
178EXPORT_SYMBOL_GPL(dma_buf_get);
179
180/**
181 * dma_buf_put - decreases refcount of the buffer
182 * @dmabuf: [in] buffer to reduce refcount of
183 *
184 * Uses file's refcounting done implicitly by fput()
185 */
186void dma_buf_put(struct dma_buf *dmabuf)
187{
188    if (WARN_ON(!dmabuf || !dmabuf->file))
189        return;
190
191    fput(dmabuf->file);
192}
193EXPORT_SYMBOL_GPL(dma_buf_put);
194
195/**
196 * dma_buf_attach - Add the device to dma_buf's attachments list; optionally,
197 * calls attach() of dma_buf_ops to allow device-specific attach functionality
198 * @dmabuf: [in] buffer to attach device to.
199 * @dev: [in] device to be attached.
200 *
201 * Returns struct dma_buf_attachment * for this attachment; may return negative
202 * error codes.
203 *
204 */
205struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,
206                      struct device *dev)
207{
208    struct dma_buf_attachment *attach;
209    int ret;
210
211    if (WARN_ON(!dmabuf || !dev))
212        return ERR_PTR(-EINVAL);
213
214    attach = kzalloc(sizeof(struct dma_buf_attachment), GFP_KERNEL);
215    if (attach == NULL)
216        return ERR_PTR(-ENOMEM);
217
218    attach->dev = dev;
219    attach->dmabuf = dmabuf;
220
221    mutex_lock(&dmabuf->lock);
222
223    if (dmabuf->ops->attach) {
224        ret = dmabuf->ops->attach(dmabuf, dev, attach);
225        if (ret)
226            goto err_attach;
227    }
228    list_add(&attach->node, &dmabuf->attachments);
229
230    mutex_unlock(&dmabuf->lock);
231    return attach;
232
233err_attach:
234    kfree(attach);
235    mutex_unlock(&dmabuf->lock);
236    return ERR_PTR(ret);
237}
238EXPORT_SYMBOL_GPL(dma_buf_attach);
239
240/**
241 * dma_buf_detach - Remove the given attachment from dmabuf's attachments list;
242 * optionally calls detach() of dma_buf_ops for device-specific detach
243 * @dmabuf: [in] buffer to detach from.
244 * @attach: [in] attachment to be detached; is free'd after this call.
245 *
246 */
247void dma_buf_detach(struct dma_buf *dmabuf, struct dma_buf_attachment *attach)
248{
249    if (WARN_ON(!dmabuf || !attach))
250        return;
251
252    mutex_lock(&dmabuf->lock);
253    list_del(&attach->node);
254    if (dmabuf->ops->detach)
255        dmabuf->ops->detach(dmabuf, attach);
256
257    mutex_unlock(&dmabuf->lock);
258    kfree(attach);
259}
260EXPORT_SYMBOL_GPL(dma_buf_detach);
261
262/**
263 * dma_buf_map_attachment - Returns the scatterlist table of the attachment;
264 * mapped into _device_ address space. Is a wrapper for map_dma_buf() of the
265 * dma_buf_ops.
266 * @attach: [in] attachment whose scatterlist is to be returned
267 * @direction: [in] direction of DMA transfer
268 *
269 * Returns sg_table containing the scatterlist to be returned; may return NULL
270 * or ERR_PTR.
271 *
272 */
273struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *attach,
274                    enum dma_data_direction direction)
275{
276    struct sg_table *sg_table = ERR_PTR(-EINVAL);
277
278    might_sleep();
279
280    if (WARN_ON(!attach || !attach->dmabuf))
281        return ERR_PTR(-EINVAL);
282
283    sg_table = attach->dmabuf->ops->map_dma_buf(attach, direction);
284
285    return sg_table;
286}
287EXPORT_SYMBOL_GPL(dma_buf_map_attachment);
288
289/**
290 * dma_buf_unmap_attachment - unmaps and decreases usecount of the buffer;might
291 * deallocate the scatterlist associated. Is a wrapper for unmap_dma_buf() of
292 * dma_buf_ops.
293 * @attach: [in] attachment to unmap buffer from
294 * @sg_table: [in] scatterlist info of the buffer to unmap
295 * @direction: [in] direction of DMA transfer
296 *
297 */
298void dma_buf_unmap_attachment(struct dma_buf_attachment *attach,
299                struct sg_table *sg_table,
300                enum dma_data_direction direction)
301{
302    might_sleep();
303
304    if (WARN_ON(!attach || !attach->dmabuf || !sg_table))
305        return;
306
307    attach->dmabuf->ops->unmap_dma_buf(attach, sg_table,
308                        direction);
309}
310EXPORT_SYMBOL_GPL(dma_buf_unmap_attachment);
311
312
313/**
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 * @dmabuf: [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.
322 *
323 * Can return negative error values, returns 0 on success.
324 */
325int dma_buf_begin_cpu_access(struct dma_buf *dmabuf, size_t start, size_t len,
326                 enum dma_data_direction direction)
327{
328    int ret = 0;
329
330    if (WARN_ON(!dmabuf))
331        return -EINVAL;
332
333    if (dmabuf->ops->begin_cpu_access)
334        ret = dmabuf->ops->begin_cpu_access(dmabuf, start, len, direction);
335
336    return ret;
337}
338EXPORT_SYMBOL_GPL(dma_buf_begin_cpu_access);
339
340/**
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 * @dmabuf: [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.
349 *
350 * This call must always succeed.
351 */
352void dma_buf_end_cpu_access(struct dma_buf *dmabuf, size_t start, size_t len,
353                enum dma_data_direction direction)
354{
355    WARN_ON(!dmabuf);
356
357    if (dmabuf->ops->end_cpu_access)
358        dmabuf->ops->end_cpu_access(dmabuf, start, len, direction);
359}
360EXPORT_SYMBOL_GPL(dma_buf_end_cpu_access);
361
362/**
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 * @dmabuf: [in] buffer to map page from.
366 * @page_num: [in] page in PAGE_SIZE units to map.
367 *
368 * This call must always succeed, any necessary preparations that might fail
369 * need to be done in begin_cpu_access.
370 */
371void *dma_buf_kmap_atomic(struct dma_buf *dmabuf, unsigned long page_num)
372{
373    WARN_ON(!dmabuf);
374
375    return dmabuf->ops->kmap_atomic(dmabuf, page_num);
376}
377EXPORT_SYMBOL_GPL(dma_buf_kmap_atomic);
378
379/**
380 * dma_buf_kunmap_atomic - Unmap a page obtained by dma_buf_kmap_atomic.
381 * @dmabuf: [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.
384 *
385 * This call must always succeed.
386 */
387void dma_buf_kunmap_atomic(struct dma_buf *dmabuf, unsigned long page_num,
388               void *vaddr)
389{
390    WARN_ON(!dmabuf);
391
392    if (dmabuf->ops->kunmap_atomic)
393        dmabuf->ops->kunmap_atomic(dmabuf, page_num, vaddr);
394}
395EXPORT_SYMBOL_GPL(dma_buf_kunmap_atomic);
396
397/**
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 * @dmabuf: [in] buffer to map page from.
401 * @page_num: [in] page in PAGE_SIZE units to map.
402 *
403 * This call must always succeed, any necessary preparations that might fail
404 * need to be done in begin_cpu_access.
405 */
406void *dma_buf_kmap(struct dma_buf *dmabuf, unsigned long page_num)
407{
408    WARN_ON(!dmabuf);
409
410    return dmabuf->ops->kmap(dmabuf, page_num);
411}
412EXPORT_SYMBOL_GPL(dma_buf_kmap);
413
414/**
415 * dma_buf_kunmap - Unmap a page obtained by dma_buf_kmap.
416 * @dmabuf: [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.
419 *
420 * This call must always succeed.
421 */
422void dma_buf_kunmap(struct dma_buf *dmabuf, unsigned long page_num,
423            void *vaddr)
424{
425    WARN_ON(!dmabuf);
426
427    if (dmabuf->ops->kunmap)
428        dmabuf->ops->kunmap(dmabuf, page_num, vaddr);
429}
430EXPORT_SYMBOL_GPL(dma_buf_kunmap);
431
432
433/**
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
438 * dma-buf buffer.
439 *
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.
444 *
445 * Can return negative error values, returns 0 on success.
446 */
447int dma_buf_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma,
448         unsigned long pgoff)
449{
450    struct file *oldfile;
451    int ret;
452
453    if (WARN_ON(!dmabuf || !vma))
454        return -EINVAL;
455
456    /* check for offset overflow */
457    if (pgoff + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) < pgoff)
458        return -EOVERFLOW;
459
460    /* check for overflowing the buffer's size */
461    if (pgoff + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) >
462        dmabuf->size >> PAGE_SHIFT)
463        return -EINVAL;
464
465    /* readjust the vma */
466    get_file(dmabuf->file);
467    oldfile = vma->vm_file;
468    vma->vm_file = dmabuf->file;
469    vma->vm_pgoff = pgoff;
470
471    ret = dmabuf->ops->mmap(dmabuf, vma);
472    if (ret) {
473        /* restore old parameters on failure */
474        vma->vm_file = oldfile;
475        fput(dmabuf->file);
476    } else {
477        if (oldfile)
478            fput(oldfile);
479    }
480    return ret;
481
482}
483EXPORT_SYMBOL_GPL(dma_buf_mmap);
484
485/**
486 * dma_buf_vmap - Create virtual mapping for the buffer object into kernel
487 * address space. Same restrictions as for vmap and friends apply.
488 * @dmabuf: [in] buffer to vmap
489 *
490 * This call may fail due to lack of virtual mapping address space.
491 * These calls are optional in drivers. The intended use for them
492 * is for mapping objects linear in kernel space for high use objects.
493 * Please attempt to use kmap/kunmap before thinking about these interfaces.
494 */
495void *dma_buf_vmap(struct dma_buf *dmabuf)
496{
497    void *ptr;
498
499    if (WARN_ON(!dmabuf))
500        return NULL;
501
502    if (!dmabuf->ops->vmap)
503        return NULL;
504
505    mutex_lock(&dmabuf->lock);
506    if (dmabuf->vmapping_counter) {
507        dmabuf->vmapping_counter++;
508        BUG_ON(!dmabuf->vmap_ptr);
509        ptr = dmabuf->vmap_ptr;
510        goto out_unlock;
511    }
512
513    BUG_ON(dmabuf->vmap_ptr);
514
515    ptr = dmabuf->ops->vmap(dmabuf);
516    if (IS_ERR_OR_NULL(ptr))
517        goto out_unlock;
518
519    dmabuf->vmap_ptr = ptr;
520    dmabuf->vmapping_counter = 1;
521
522out_unlock:
523    mutex_unlock(&dmabuf->lock);
524    return ptr;
525}
526EXPORT_SYMBOL_GPL(dma_buf_vmap);
527
528/**
529 * dma_buf_vunmap - Unmap a vmap obtained by dma_buf_vmap.
530 * @dmabuf: [in] buffer to vunmap
531 * @vaddr: [in] vmap to vunmap
532 */
533void dma_buf_vunmap(struct dma_buf *dmabuf, void *vaddr)
534{
535    if (WARN_ON(!dmabuf))
536        return;
537
538    BUG_ON(!dmabuf->vmap_ptr);
539    BUG_ON(dmabuf->vmapping_counter == 0);
540    BUG_ON(dmabuf->vmap_ptr != vaddr);
541
542    mutex_lock(&dmabuf->lock);
543    if (--dmabuf->vmapping_counter == 0) {
544        if (dmabuf->ops->vunmap)
545            dmabuf->ops->vunmap(dmabuf, vaddr);
546        dmabuf->vmap_ptr = NULL;
547    }
548    mutex_unlock(&dmabuf->lock);
549}
550EXPORT_SYMBOL_GPL(dma_buf_vunmap);
551

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