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	dmabuf->ops->release(dmabuf);
43	kfree(dmabuf);
44	return 0;
45}
46
47static int dma_buf_mmap_internal(struct file *file, struct vm_area_struct *vma)
48{
49	struct dma_buf *dmabuf;
50
51	if (!is_dma_buf_file(file))
52		return -EINVAL;
53
54	dmabuf = file->private_data;
55
56	/* check for overflowing the buffer's size */
57	if (vma->vm_pgoff + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) >
58	    dmabuf->size >> PAGE_SHIFT)
59		return -EINVAL;
60
61	return dmabuf->ops->mmap(dmabuf, vma);
62}
63
64static const struct file_operations dma_buf_fops = {
65	.release	= dma_buf_release,
66	.mmap		= dma_buf_mmap_internal,
67};
68
69/*
70 * is_dma_buf_file - Check if struct file* is associated with dma_buf
71 */
72static inline int is_dma_buf_file(struct file *file)
73{
74	return file->f_op == &dma_buf_fops;
75}
76
77/**
78 * dma_buf_export - Creates a new dma_buf, and associates an anon file
79 * with this buffer, so it can be exported.
80 * Also connect the allocator specific data and ops to the buffer.
81 *
82 * @priv:	[in]	Attach private data of allocator to this buffer
83 * @ops:	[in]	Attach allocator-defined dma buf ops to the new buffer.
84 * @size:	[in]	Size of the buffer
85 * @flags:	[in]	mode flags for the file.
86 *
87 * Returns, on success, a newly created dma_buf object, which wraps the
88 * supplied private data and operations for dma_buf_ops. On either missing
89 * ops, or error in allocating struct dma_buf, will return negative error.
90 *
91 */
92struct dma_buf *dma_buf_export(void *priv, const struct dma_buf_ops *ops,
93				size_t size, int flags)
94{
95	struct dma_buf *dmabuf;
96	struct file *file;
97
98	if (WARN_ON(!priv || !ops
99			  || !ops->map_dma_buf
100			  || !ops->unmap_dma_buf
101			  || !ops->release
102			  || !ops->kmap_atomic
103			  || !ops->kmap
104			  || !ops->mmap)) {
105		return ERR_PTR(-EINVAL);
106	}
107
108	dmabuf = kzalloc(sizeof(struct dma_buf), GFP_KERNEL);
109	if (dmabuf == NULL)
110		return ERR_PTR(-ENOMEM);
111
112	dmabuf->priv = priv;
113	dmabuf->ops = ops;
114	dmabuf->size = size;
115
116	file = anon_inode_getfile("dmabuf", &dma_buf_fops, dmabuf, flags);
117
118	dmabuf->file = file;
119
120	mutex_init(&dmabuf->lock);
121	INIT_LIST_HEAD(&dmabuf->attachments);
122
123	return dmabuf;
124}
125EXPORT_SYMBOL_GPL(dma_buf_export);
126
127
128/**
129 * dma_buf_fd - returns a file descriptor for the given dma_buf
130 * @dmabuf:	[in]	pointer to dma_buf for which fd is required.
131 * @flags:      [in]    flags to give to fd
132 *
133 * On success, returns an associated 'fd'. Else, returns error.
134 */
135int dma_buf_fd(struct dma_buf *dmabuf, int flags)
136{
137	int error, fd;
138
139	if (!dmabuf || !dmabuf->file)
140		return -EINVAL;
141
142	error = get_unused_fd_flags(flags);
143	if (error < 0)
144		return error;
145	fd = error;
146
147	fd_install(fd, dmabuf->file);
148
149	return fd;
150}
151EXPORT_SYMBOL_GPL(dma_buf_fd);
152
153/**
154 * dma_buf_get - returns the dma_buf structure related to an fd
155 * @fd:	[in]	fd associated with the dma_buf to be returned
156 *
157 * On success, returns the dma_buf structure associated with an fd; uses
158 * file's refcounting done by fget to increase refcount. returns ERR_PTR
159 * otherwise.
160 */
161struct dma_buf *dma_buf_get(int fd)
162{
163	struct file *file;
164
165	file = fget(fd);
166
167	if (!file)
168		return ERR_PTR(-EBADF);
169
170	if (!is_dma_buf_file(file)) {
171		fput(file);
172		return ERR_PTR(-EINVAL);
173	}
174
175	return file->private_data;
176}
177EXPORT_SYMBOL_GPL(dma_buf_get);
178
179/**
180 * dma_buf_put - decreases refcount of the buffer
181 * @dmabuf:	[in]	buffer to reduce refcount of
182 *
183 * Uses file's refcounting done implicitly by fput()
184 */
185void dma_buf_put(struct dma_buf *dmabuf)
186{
187	if (WARN_ON(!dmabuf || !dmabuf->file))
188		return;
189
190	fput(dmabuf->file);
191}
192EXPORT_SYMBOL_GPL(dma_buf_put);
193
194/**
195 * dma_buf_attach - Add the device to dma_buf's attachments list; optionally,
196 * calls attach() of dma_buf_ops to allow device-specific attach functionality
197 * @dmabuf:	[in]	buffer to attach device to.
198 * @dev:	[in]	device to be attached.
199 *
200 * Returns struct dma_buf_attachment * for this attachment; may return negative
201 * error codes.
202 *
203 */
204struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,
205					  struct device *dev)
206{
207	struct dma_buf_attachment *attach;
208	int ret;
209
210	if (WARN_ON(!dmabuf || !dev))
211		return ERR_PTR(-EINVAL);
212
213	attach = kzalloc(sizeof(struct dma_buf_attachment), GFP_KERNEL);
214	if (attach == NULL)
215		return ERR_PTR(-ENOMEM);
216
217	attach->dev = dev;
218	attach->dmabuf = dmabuf;
219
220	mutex_lock(&dmabuf->lock);
221
222	if (dmabuf->ops->attach) {
223		ret = dmabuf->ops->attach(dmabuf, dev, attach);
224		if (ret)
225			goto err_attach;
226	}
227	list_add(&attach->node, &dmabuf->attachments);
228
229	mutex_unlock(&dmabuf->lock);
230	return attach;
231
232err_attach:
233	kfree(attach);
234	mutex_unlock(&dmabuf->lock);
235	return ERR_PTR(ret);
236}
237EXPORT_SYMBOL_GPL(dma_buf_attach);
238
239/**
240 * dma_buf_detach - Remove the given attachment from dmabuf's attachments list;
241 * optionally calls detach() of dma_buf_ops for device-specific detach
242 * @dmabuf:	[in]	buffer to detach from.
243 * @attach:	[in]	attachment to be detached; is free'd after this call.
244 *
245 */
246void dma_buf_detach(struct dma_buf *dmabuf, struct dma_buf_attachment *attach)
247{
248	if (WARN_ON(!dmabuf || !attach))
249		return;
250
251	mutex_lock(&dmabuf->lock);
252	list_del(&attach->node);
253	if (dmabuf->ops->detach)
254		dmabuf->ops->detach(dmabuf, attach);
255
256	mutex_unlock(&dmabuf->lock);
257	kfree(attach);
258}
259EXPORT_SYMBOL_GPL(dma_buf_detach);
260
261/**
262 * dma_buf_map_attachment - Returns the scatterlist table of the attachment;
263 * mapped into _device_ address space. Is a wrapper for map_dma_buf() of the
264 * dma_buf_ops.
265 * @attach:	[in]	attachment whose scatterlist is to be returned
266 * @direction:	[in]	direction of DMA transfer
267 *
268 * Returns sg_table containing the scatterlist to be returned; may return NULL
269 * or ERR_PTR.
270 *
271 */
272struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *attach,
273					enum dma_data_direction direction)
274{
275	struct sg_table *sg_table = ERR_PTR(-EINVAL);
276
277	might_sleep();
278
279	if (WARN_ON(!attach || !attach->dmabuf))
280		return ERR_PTR(-EINVAL);
281
282	sg_table = attach->dmabuf->ops->map_dma_buf(attach, direction);
283
284	return sg_table;
285}
286EXPORT_SYMBOL_GPL(dma_buf_map_attachment);
287
288/**
289 * dma_buf_unmap_attachment - unmaps and decreases usecount of the buffer;might
290 * deallocate the scatterlist associated. Is a wrapper for unmap_dma_buf() of
291 * dma_buf_ops.
292 * @attach:	[in]	attachment to unmap buffer from
293 * @sg_table:	[in]	scatterlist info of the buffer to unmap
294 * @direction:  [in]    direction of DMA transfer
295 *
296 */
297void dma_buf_unmap_attachment(struct dma_buf_attachment *attach,
298				struct sg_table *sg_table,
299				enum dma_data_direction direction)
300{
301	if (WARN_ON(!attach || !attach->dmabuf || !sg_table))
302		return;
303
304	attach->dmabuf->ops->unmap_dma_buf(attach, sg_table,
305						direction);
306}
307EXPORT_SYMBOL_GPL(dma_buf_unmap_attachment);
308
309
310/**
311 * dma_buf_begin_cpu_access - Must be called before accessing a dma_buf from the
312 * cpu in the kernel context. Calls begin_cpu_access to allow exporter-specific
313 * preparations. Coherency is only guaranteed in the specified range for the
314 * specified access direction.
315 * @dma_buf:	[in]	buffer to prepare cpu access for.
316 * @start:	[in]	start of range for cpu access.
317 * @len:	[in]	length of range for cpu access.
318 * @direction:	[in]	length of range for cpu access.
319 *
320 * Can return negative error values, returns 0 on success.
321 */
322int dma_buf_begin_cpu_access(struct dma_buf *dmabuf, size_t start, size_t len,
323			     enum dma_data_direction direction)
324{
325	int ret = 0;
326
327	if (WARN_ON(!dmabuf))
328		return -EINVAL;
329
330	if (dmabuf->ops->begin_cpu_access)
331		ret = dmabuf->ops->begin_cpu_access(dmabuf, start, len, direction);
332
333	return ret;
334}
335EXPORT_SYMBOL_GPL(dma_buf_begin_cpu_access);
336
337/**
338 * dma_buf_end_cpu_access - Must be called after accessing a dma_buf from the
339 * cpu in the kernel context. Calls end_cpu_access to allow exporter-specific
340 * actions. Coherency is only guaranteed in the specified range for the
341 * specified access direction.
342 * @dma_buf:	[in]	buffer to complete cpu access for.
343 * @start:	[in]	start of range for cpu access.
344 * @len:	[in]	length of range for cpu access.
345 * @direction:	[in]	length of range for cpu access.
346 *
347 * This call must always succeed.
348 */
349void dma_buf_end_cpu_access(struct dma_buf *dmabuf, size_t start, size_t len,
350			    enum dma_data_direction direction)
351{
352	WARN_ON(!dmabuf);
353
354	if (dmabuf->ops->end_cpu_access)
355		dmabuf->ops->end_cpu_access(dmabuf, start, len, direction);
356}
357EXPORT_SYMBOL_GPL(dma_buf_end_cpu_access);
358
359/**
360 * dma_buf_kmap_atomic - Map a page of the buffer object into kernel address
361 * space. The same restrictions as for kmap_atomic and friends apply.
362 * @dma_buf:	[in]	buffer to map page from.
363 * @page_num:	[in]	page in PAGE_SIZE units to map.
364 *
365 * This call must always succeed, any necessary preparations that might fail
366 * need to be done in begin_cpu_access.
367 */
368void *dma_buf_kmap_atomic(struct dma_buf *dmabuf, unsigned long page_num)
369{
370	WARN_ON(!dmabuf);
371
372	return dmabuf->ops->kmap_atomic(dmabuf, page_num);
373}
374EXPORT_SYMBOL_GPL(dma_buf_kmap_atomic);
375
376/**
377 * dma_buf_kunmap_atomic - Unmap a page obtained by dma_buf_kmap_atomic.
378 * @dma_buf:	[in]	buffer to unmap page from.
379 * @page_num:	[in]	page in PAGE_SIZE units to unmap.
380 * @vaddr:	[in]	kernel space pointer obtained from dma_buf_kmap_atomic.
381 *
382 * This call must always succeed.
383 */
384void dma_buf_kunmap_atomic(struct dma_buf *dmabuf, unsigned long page_num,
385			   void *vaddr)
386{
387	WARN_ON(!dmabuf);
388
389	if (dmabuf->ops->kunmap_atomic)
390		dmabuf->ops->kunmap_atomic(dmabuf, page_num, vaddr);
391}
392EXPORT_SYMBOL_GPL(dma_buf_kunmap_atomic);
393
394/**
395 * dma_buf_kmap - Map a page of the buffer object into kernel address space. The
396 * same restrictions as for kmap and friends apply.
397 * @dma_buf:	[in]	buffer to map page from.
398 * @page_num:	[in]	page in PAGE_SIZE units to map.
399 *
400 * This call must always succeed, any necessary preparations that might fail
401 * need to be done in begin_cpu_access.
402 */
403void *dma_buf_kmap(struct dma_buf *dmabuf, unsigned long page_num)
404{
405	WARN_ON(!dmabuf);
406
407	return dmabuf->ops->kmap(dmabuf, page_num);
408}
409EXPORT_SYMBOL_GPL(dma_buf_kmap);
410
411/**
412 * dma_buf_kunmap - Unmap a page obtained by dma_buf_kmap.
413 * @dma_buf:	[in]	buffer to unmap page from.
414 * @page_num:	[in]	page in PAGE_SIZE units to unmap.
415 * @vaddr:	[in]	kernel space pointer obtained from dma_buf_kmap.
416 *
417 * This call must always succeed.
418 */
419void dma_buf_kunmap(struct dma_buf *dmabuf, unsigned long page_num,
420		    void *vaddr)
421{
422	WARN_ON(!dmabuf);
423
424	if (dmabuf->ops->kunmap)
425		dmabuf->ops->kunmap(dmabuf, page_num, vaddr);
426}
427EXPORT_SYMBOL_GPL(dma_buf_kunmap);
428
429
430/**
431 * dma_buf_mmap - Setup up a userspace mmap with the given vma
432 * @dma_buf:	[in]	buffer that should back the vma
433 * @vma:	[in]	vma for the mmap
434 * @pgoff:	[in]	offset in pages where this mmap should start within the
435 * 			dma-buf buffer.
436 *
437 * This function adjusts the passed in vma so that it points at the file of the
438 * dma_buf operation. It alsog adjusts the starting pgoff and does bounds
439 * checking on the size of the vma. Then it calls the exporters mmap function to
440 * set up the mapping.
441 *
442 * Can return negative error values, returns 0 on success.
443 */
444int dma_buf_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma,
445		 unsigned long pgoff)
446{
447	if (WARN_ON(!dmabuf || !vma))
448		return -EINVAL;
449
450	/* check for offset overflow */
451	if (pgoff + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) < pgoff)
452		return -EOVERFLOW;
453
454	/* check for overflowing the buffer's size */
455	if (pgoff + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) >
456	    dmabuf->size >> PAGE_SHIFT)
457		return -EINVAL;
458
459	/* readjust the vma */
460	if (vma->vm_file)
461		fput(vma->vm_file);
462
463	vma->vm_file = dmabuf->file;
464	get_file(vma->vm_file);
465
466	vma->vm_pgoff = pgoff;
467
468	return dmabuf->ops->mmap(dmabuf, vma);
469}
470EXPORT_SYMBOL_GPL(dma_buf_mmap);
471