1/*
2 * Header file for dma buffer sharing framework.
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#ifndef __DMA_BUF_H__
25#define __DMA_BUF_H__
26
27#include <linux/file.h>
28#include <linux/err.h>
29#include <linux/scatterlist.h>
30#include <linux/list.h>
31#include <linux/dma-mapping.h>
32#include <linux/fs.h>
33
34struct device;
35struct dma_buf;
36struct dma_buf_attachment;
37
38/**
39 * struct dma_buf_ops - operations possible on struct dma_buf
40 * @attach: [optional] allows different devices to 'attach' themselves to the
41 *	    given buffer. It might return -EBUSY to signal that backing storage
42 *	    is already allocated and incompatible with the requirements
43 *	    of requesting device.
44 * @detach: [optional] detach a given device from this buffer.
45 * @map_dma_buf: returns list of scatter pages allocated, increases usecount
46 *		 of the buffer. Requires atleast one attach to be called
47 *		 before. Returned sg list should already be mapped into
48 *		 _device_ address space. This call may sleep. May also return
49 *		 -EINTR. Should return -EINVAL if attach hasn't been called yet.
50 * @unmap_dma_buf: decreases usecount of buffer, might deallocate scatter
51 *		   pages.
52 * @release: release this buffer; to be called after the last dma_buf_put.
53 * @begin_cpu_access: [optional] called before cpu access to invalidate cpu
54 * 		      caches and allocate backing storage (if not yet done)
55 * 		      respectively pin the objet into memory.
56 * @end_cpu_access: [optional] called after cpu access to flush cashes.
57 * @kmap_atomic: maps a page from the buffer into kernel address
58 * 		 space, users may not block until the subsequent unmap call.
59 * 		 This callback must not sleep.
60 * @kunmap_atomic: [optional] unmaps a atomically mapped page from the buffer.
61 * 		   This Callback must not sleep.
62 * @kmap: maps a page from the buffer into kernel address space.
63 * @kunmap: [optional] unmaps a page from the buffer.
64 * @mmap: used to expose the backing storage to userspace. Note that the
65 * 	  mapping needs to be coherent - if the exporter doesn't directly
66 * 	  support this, it needs to fake coherency by shooting down any ptes
67 * 	  when transitioning away from the cpu domain.
68 */
69struct dma_buf_ops {
70	int (*attach)(struct dma_buf *, struct device *,
71			struct dma_buf_attachment *);
72
73	void (*detach)(struct dma_buf *, struct dma_buf_attachment *);
74
75	/* For {map,unmap}_dma_buf below, any specific buffer attributes
76	 * required should get added to device_dma_parameters accessible
77	 * via dev->dma_params.
78	 */
79	struct sg_table * (*map_dma_buf)(struct dma_buf_attachment *,
80						enum dma_data_direction);
81	void (*unmap_dma_buf)(struct dma_buf_attachment *,
82						struct sg_table *,
83						enum dma_data_direction);
84	/* TODO: Add try_map_dma_buf version, to return immed with -EBUSY
85	 * if the call would block.
86	 */
87
88	/* after final dma_buf_put() */
89	void (*release)(struct dma_buf *);
90
91	int (*begin_cpu_access)(struct dma_buf *, size_t, size_t,
92				enum dma_data_direction);
93	void (*end_cpu_access)(struct dma_buf *, size_t, size_t,
94			       enum dma_data_direction);
95	void *(*kmap_atomic)(struct dma_buf *, unsigned long);
96	void (*kunmap_atomic)(struct dma_buf *, unsigned long, void *);
97	void *(*kmap)(struct dma_buf *, unsigned long);
98	void (*kunmap)(struct dma_buf *, unsigned long, void *);
99
100	int (*mmap)(struct dma_buf *, struct vm_area_struct *vma);
101};
102
103/**
104 * struct dma_buf - shared buffer object
105 * @size: size of the buffer
106 * @file: file pointer used for sharing buffers across, and for refcounting.
107 * @attachments: list of dma_buf_attachment that denotes all devices attached.
108 * @ops: dma_buf_ops associated with this buffer object.
109 * @priv: exporter specific private data for this buffer object.
110 */
111struct dma_buf {
112	size_t size;
113	struct file *file;
114	struct list_head attachments;
115	const struct dma_buf_ops *ops;
116	/* mutex to serialize list manipulation and attach/detach */
117	struct mutex lock;
118	void *priv;
119};
120
121/**
122 * struct dma_buf_attachment - holds device-buffer attachment data
123 * @dmabuf: buffer for this attachment.
124 * @dev: device attached to the buffer.
125 * @node: list of dma_buf_attachment.
126 * @priv: exporter specific attachment data.
127 *
128 * This structure holds the attachment information between the dma_buf buffer
129 * and its user device(s). The list contains one attachment struct per device
130 * attached to the buffer.
131 */
132struct dma_buf_attachment {
133	struct dma_buf *dmabuf;
134	struct device *dev;
135	struct list_head node;
136	void *priv;
137};
138
139/**
140 * get_dma_buf - convenience wrapper for get_file.
141 * @dmabuf:	[in]	pointer to dma_buf
142 *
143 * Increments the reference count on the dma-buf, needed in case of drivers
144 * that either need to create additional references to the dmabuf on the
145 * kernel side.  For example, an exporter that needs to keep a dmabuf ptr
146 * so that subsequent exports don't create a new dmabuf.
147 */
148static inline void get_dma_buf(struct dma_buf *dmabuf)
149{
150	get_file(dmabuf->file);
151}
152
153#ifdef CONFIG_DMA_SHARED_BUFFER
154struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,
155							struct device *dev);
156void dma_buf_detach(struct dma_buf *dmabuf,
157				struct dma_buf_attachment *dmabuf_attach);
158struct dma_buf *dma_buf_export(void *priv, const struct dma_buf_ops *ops,
159			       size_t size, int flags);
160int dma_buf_fd(struct dma_buf *dmabuf, int flags);
161struct dma_buf *dma_buf_get(int fd);
162void dma_buf_put(struct dma_buf *dmabuf);
163
164struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *,
165					enum dma_data_direction);
166void dma_buf_unmap_attachment(struct dma_buf_attachment *, struct sg_table *,
167				enum dma_data_direction);
168int dma_buf_begin_cpu_access(struct dma_buf *dma_buf, size_t start, size_t len,
169			     enum dma_data_direction dir);
170void dma_buf_end_cpu_access(struct dma_buf *dma_buf, size_t start, size_t len,
171			    enum dma_data_direction dir);
172void *dma_buf_kmap_atomic(struct dma_buf *, unsigned long);
173void dma_buf_kunmap_atomic(struct dma_buf *, unsigned long, void *);
174void *dma_buf_kmap(struct dma_buf *, unsigned long);
175void dma_buf_kunmap(struct dma_buf *, unsigned long, void *);
176
177int dma_buf_mmap(struct dma_buf *, struct vm_area_struct *,
178		 unsigned long);
179#else
180
181static inline struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,
182							struct device *dev)
183{
184	return ERR_PTR(-ENODEV);
185}
186
187static inline void dma_buf_detach(struct dma_buf *dmabuf,
188				  struct dma_buf_attachment *dmabuf_attach)
189{
190	return;
191}
192
193static inline struct dma_buf *dma_buf_export(void *priv,
194					     const struct dma_buf_ops *ops,
195					     size_t size, int flags)
196{
197	return ERR_PTR(-ENODEV);
198}
199
200static inline int dma_buf_fd(struct dma_buf *dmabuf, int flags)
201{
202	return -ENODEV;
203}
204
205static inline struct dma_buf *dma_buf_get(int fd)
206{
207	return ERR_PTR(-ENODEV);
208}
209
210static inline void dma_buf_put(struct dma_buf *dmabuf)
211{
212	return;
213}
214
215static inline struct sg_table *dma_buf_map_attachment(
216	struct dma_buf_attachment *attach, enum dma_data_direction write)
217{
218	return ERR_PTR(-ENODEV);
219}
220
221static inline void dma_buf_unmap_attachment(struct dma_buf_attachment *attach,
222			struct sg_table *sg, enum dma_data_direction dir)
223{
224	return;
225}
226
227static inline int dma_buf_begin_cpu_access(struct dma_buf *dmabuf,
228					   size_t start, size_t len,
229					   enum dma_data_direction dir)
230{
231	return -ENODEV;
232}
233
234static inline void dma_buf_end_cpu_access(struct dma_buf *dmabuf,
235					  size_t start, size_t len,
236					  enum dma_data_direction dir)
237{
238}
239
240static inline void *dma_buf_kmap_atomic(struct dma_buf *dmabuf,
241					unsigned long pnum)
242{
243	return NULL;
244}
245
246static inline void dma_buf_kunmap_atomic(struct dma_buf *dmabuf,
247					 unsigned long pnum, void *vaddr)
248{
249}
250
251static inline void *dma_buf_kmap(struct dma_buf *dmabuf, unsigned long pnum)
252{
253	return NULL;
254}
255
256static inline void dma_buf_kunmap(struct dma_buf *dmabuf,
257				  unsigned long pnum, void *vaddr)
258{
259}
260
261static inline int dma_buf_mmap(struct dma_buf *dmabuf,
262			       struct vm_area_struct *vma,
263			       unsigned long pgoff)
264{
265	return -ENODEV;
266}
267#endif /* CONFIG_DMA_SHARED_BUFFER */
268
269#endif /* __DMA_BUF_H__ */
270