blob: e38ad243b4bbec7104e305cada1d15199299e4f2 [file] [log] [blame]
Sumit Semwald15bd7e2011-12-26 14:53:15 +05301/*
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 const struct file_operations dma_buf_fops = {
48 .release = dma_buf_release,
49};
50
51/*
52 * is_dma_buf_file - Check if struct file* is associated with dma_buf
53 */
54static inline int is_dma_buf_file(struct file *file)
55{
56 return file->f_op == &dma_buf_fops;
57}
58
59/**
60 * dma_buf_export - Creates a new dma_buf, and associates an anon file
61 * with this buffer, so it can be exported.
62 * Also connect the allocator specific data and ops to the buffer.
63 *
64 * @priv: [in] Attach private data of allocator to this buffer
65 * @ops: [in] Attach allocator-defined dma buf ops to the new buffer.
66 * @size: [in] Size of the buffer
67 * @flags: [in] mode flags for the file.
68 *
69 * Returns, on success, a newly created dma_buf object, which wraps the
70 * supplied private data and operations for dma_buf_ops. On either missing
71 * ops, or error in allocating struct dma_buf, will return negative error.
72 *
73 */
74struct dma_buf *dma_buf_export(void *priv, struct dma_buf_ops *ops,
75 size_t size, int flags)
76{
77 struct dma_buf *dmabuf;
78 struct file *file;
79
80 if (WARN_ON(!priv || !ops
81 || !ops->map_dma_buf
82 || !ops->unmap_dma_buf
83 || !ops->release)) {
84 return ERR_PTR(-EINVAL);
85 }
86
87 dmabuf = kzalloc(sizeof(struct dma_buf), GFP_KERNEL);
88 if (dmabuf == NULL)
89 return ERR_PTR(-ENOMEM);
90
91 dmabuf->priv = priv;
92 dmabuf->ops = ops;
93 dmabuf->size = size;
94
95 file = anon_inode_getfile("dmabuf", &dma_buf_fops, dmabuf, flags);
96
97 dmabuf->file = file;
98
99 mutex_init(&dmabuf->lock);
100 INIT_LIST_HEAD(&dmabuf->attachments);
101
102 return dmabuf;
103}
104EXPORT_SYMBOL_GPL(dma_buf_export);
105
106
107/**
108 * dma_buf_fd - returns a file descriptor for the given dma_buf
109 * @dmabuf: [in] pointer to dma_buf for which fd is required.
110 *
111 * On success, returns an associated 'fd'. Else, returns error.
112 */
113int dma_buf_fd(struct dma_buf *dmabuf)
114{
115 int error, fd;
116
117 if (!dmabuf || !dmabuf->file)
118 return -EINVAL;
119
120 error = get_unused_fd();
121 if (error < 0)
122 return error;
123 fd = error;
124
125 fd_install(fd, dmabuf->file);
126
127 return fd;
128}
129EXPORT_SYMBOL_GPL(dma_buf_fd);
130
131/**
132 * dma_buf_get - returns the dma_buf structure related to an fd
133 * @fd: [in] fd associated with the dma_buf to be returned
134 *
135 * On success, returns the dma_buf structure associated with an fd; uses
136 * file's refcounting done by fget to increase refcount. returns ERR_PTR
137 * otherwise.
138 */
139struct dma_buf *dma_buf_get(int fd)
140{
141 struct file *file;
142
143 file = fget(fd);
144
145 if (!file)
146 return ERR_PTR(-EBADF);
147
148 if (!is_dma_buf_file(file)) {
149 fput(file);
150 return ERR_PTR(-EINVAL);
151 }
152
153 return file->private_data;
154}
155EXPORT_SYMBOL_GPL(dma_buf_get);
156
157/**
158 * dma_buf_put - decreases refcount of the buffer
159 * @dmabuf: [in] buffer to reduce refcount of
160 *
161 * Uses file's refcounting done implicitly by fput()
162 */
163void dma_buf_put(struct dma_buf *dmabuf)
164{
165 if (WARN_ON(!dmabuf || !dmabuf->file))
166 return;
167
168 fput(dmabuf->file);
169}
170EXPORT_SYMBOL_GPL(dma_buf_put);
171
172/**
173 * dma_buf_attach - Add the device to dma_buf's attachments list; optionally,
174 * calls attach() of dma_buf_ops to allow device-specific attach functionality
175 * @dmabuf: [in] buffer to attach device to.
176 * @dev: [in] device to be attached.
177 *
178 * Returns struct dma_buf_attachment * for this attachment; may return negative
179 * error codes.
180 *
181 */
182struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,
183 struct device *dev)
184{
185 struct dma_buf_attachment *attach;
186 int ret;
187
188 if (WARN_ON(!dmabuf || !dev || !dmabuf->ops))
189 return ERR_PTR(-EINVAL);
190
191 attach = kzalloc(sizeof(struct dma_buf_attachment), GFP_KERNEL);
192 if (attach == NULL)
193 goto err_alloc;
194
195 mutex_lock(&dmabuf->lock);
196
197 attach->dev = dev;
198 attach->dmabuf = dmabuf;
199 if (dmabuf->ops->attach) {
200 ret = dmabuf->ops->attach(dmabuf, dev, attach);
201 if (ret)
202 goto err_attach;
203 }
204 list_add(&attach->node, &dmabuf->attachments);
205
206 mutex_unlock(&dmabuf->lock);
207 return attach;
208
209err_alloc:
210 return ERR_PTR(-ENOMEM);
211err_attach:
212 kfree(attach);
213 mutex_unlock(&dmabuf->lock);
214 return ERR_PTR(ret);
215}
216EXPORT_SYMBOL_GPL(dma_buf_attach);
217
218/**
219 * dma_buf_detach - Remove the given attachment from dmabuf's attachments list;
220 * optionally calls detach() of dma_buf_ops for device-specific detach
221 * @dmabuf: [in] buffer to detach from.
222 * @attach: [in] attachment to be detached; is free'd after this call.
223 *
224 */
225void dma_buf_detach(struct dma_buf *dmabuf, struct dma_buf_attachment *attach)
226{
227 if (WARN_ON(!dmabuf || !attach || !dmabuf->ops))
228 return;
229
230 mutex_lock(&dmabuf->lock);
231 list_del(&attach->node);
232 if (dmabuf->ops->detach)
233 dmabuf->ops->detach(dmabuf, attach);
234
235 mutex_unlock(&dmabuf->lock);
236 kfree(attach);
237}
238EXPORT_SYMBOL_GPL(dma_buf_detach);
239
240/**
241 * dma_buf_map_attachment - Returns the scatterlist table of the attachment;
242 * mapped into _device_ address space. Is a wrapper for map_dma_buf() of the
243 * dma_buf_ops.
244 * @attach: [in] attachment whose scatterlist is to be returned
245 * @direction: [in] direction of DMA transfer
246 *
247 * Returns sg_table containing the scatterlist to be returned; may return NULL
248 * or ERR_PTR.
249 *
250 */
251struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *attach,
252 enum dma_data_direction direction)
253{
254 struct sg_table *sg_table = ERR_PTR(-EINVAL);
255
256 might_sleep();
257
258 if (WARN_ON(!attach || !attach->dmabuf || !attach->dmabuf->ops))
259 return ERR_PTR(-EINVAL);
260
261 mutex_lock(&attach->dmabuf->lock);
262 if (attach->dmabuf->ops->map_dma_buf)
263 sg_table = attach->dmabuf->ops->map_dma_buf(attach, direction);
264 mutex_unlock(&attach->dmabuf->lock);
265
266 return sg_table;
267}
268EXPORT_SYMBOL_GPL(dma_buf_map_attachment);
269
270/**
271 * dma_buf_unmap_attachment - unmaps and decreases usecount of the buffer;might
272 * deallocate the scatterlist associated. Is a wrapper for unmap_dma_buf() of
273 * dma_buf_ops.
274 * @attach: [in] attachment to unmap buffer from
275 * @sg_table: [in] scatterlist info of the buffer to unmap
276 *
277 */
278void dma_buf_unmap_attachment(struct dma_buf_attachment *attach,
279 struct sg_table *sg_table)
280{
281 if (WARN_ON(!attach || !attach->dmabuf || !sg_table
282 || !attach->dmabuf->ops))
283 return;
284
285 mutex_lock(&attach->dmabuf->lock);
286 if (attach->dmabuf->ops->unmap_dma_buf)
287 attach->dmabuf->ops->unmap_dma_buf(attach, sg_table);
288 mutex_unlock(&attach->dmabuf->lock);
289
290}
291EXPORT_SYMBOL_GPL(dma_buf_unmap_attachment);