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
34 struct device;
35 struct dma_buf;
36 struct 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 caches.
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 * @vmap: [optional] creates a virtual mapping for the buffer into kernel
69 * address space. Same restrictions as for vmap and friends apply.
70 * @vunmap: [optional] unmaps a vmap from the buffer
71 */
72 struct dma_buf_ops {
73 int (*attach)(struct dma_buf *, struct device *,
74 struct dma_buf_attachment *);
75
76 void (*detach)(struct dma_buf *, struct dma_buf_attachment *);
77
78 /* For {map,unmap}_dma_buf below, any specific buffer attributes
79 * required should get added to device_dma_parameters accessible
80 * via dev->dma_params.
81 */
82 struct sg_table * (*map_dma_buf)(struct dma_buf_attachment *,
83 enum dma_data_direction);
84 void (*unmap_dma_buf)(struct dma_buf_attachment *,
85 struct sg_table *,
86 enum dma_data_direction);
87 /* TODO: Add try_map_dma_buf version, to return immed with -EBUSY
88 * if the call would block.
89 */
90
91 /* after final dma_buf_put() */
92 void (*release)(struct dma_buf *);
93
94 int (*begin_cpu_access)(struct dma_buf *, size_t, size_t,
95 enum dma_data_direction);
96 void (*end_cpu_access)(struct dma_buf *, size_t, size_t,
97 enum dma_data_direction);
98 void *(*kmap_atomic)(struct dma_buf *, unsigned long);
99 void (*kunmap_atomic)(struct dma_buf *, unsigned long, void *);
100 void *(*kmap)(struct dma_buf *, unsigned long);
101 void (*kunmap)(struct dma_buf *, unsigned long, void *);
102
103 int (*mmap)(struct dma_buf *, struct vm_area_struct *vma);
104
105 void *(*vmap)(struct dma_buf *);
106 void (*vunmap)(struct dma_buf *, void *vaddr);
107 };
108
109 /**
110 * struct dma_buf - shared buffer object
111 * @size: size of the buffer
112 * @file: file pointer used for sharing buffers across, and for refcounting.
113 * @attachments: list of dma_buf_attachment that denotes all devices attached.
114 * @ops: dma_buf_ops associated with this buffer object.
115 * @exp_name: name of the exporter; useful for debugging.
116 * @list_node: node for dma_buf accounting and debugging.
117 * @priv: exporter specific private data for this buffer object.
118 */
119 struct dma_buf {
120 size_t size;
121 struct file *file;
122 struct list_head attachments;
123 const struct dma_buf_ops *ops;
124 /* mutex to serialize list manipulation, attach/detach and vmap/unmap */
125 struct mutex lock;
126 unsigned vmapping_counter;
127 void *vmap_ptr;
128 const char *exp_name;
129 struct list_head list_node;
130 void *priv;
131 };
132
133 /**
134 * struct dma_buf_attachment - holds device-buffer attachment data
135 * @dmabuf: buffer for this attachment.
136 * @dev: device attached to the buffer.
137 * @node: list of dma_buf_attachment.
138 * @priv: exporter specific attachment data.
139 *
140 * This structure holds the attachment information between the dma_buf buffer
141 * and its user device(s). The list contains one attachment struct per device
142 * attached to the buffer.
143 */
144 struct dma_buf_attachment {
145 struct dma_buf *dmabuf;
146 struct device *dev;
147 struct list_head node;
148 void *priv;
149 };
150
151 /**
152 * get_dma_buf - convenience wrapper for get_file.
153 * @dmabuf: [in] pointer to dma_buf
154 *
155 * Increments the reference count on the dma-buf, needed in case of drivers
156 * that either need to create additional references to the dmabuf on the
157 * kernel side. For example, an exporter that needs to keep a dmabuf ptr
158 * so that subsequent exports don't create a new dmabuf.
159 */
get_dma_buf(struct dma_buf * dmabuf)160 static inline void get_dma_buf(struct dma_buf *dmabuf)
161 {
162 get_file(dmabuf->file);
163 }
164
165 struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,
166 struct device *dev);
167 void dma_buf_detach(struct dma_buf *dmabuf,
168 struct dma_buf_attachment *dmabuf_attach);
169
170 struct dma_buf *dma_buf_export_named(void *priv, const struct dma_buf_ops *ops,
171 size_t size, int flags, const char *);
172
173 #define dma_buf_export(priv, ops, size, flags) \
174 dma_buf_export_named(priv, ops, size, flags, __FILE__)
175
176 int dma_buf_fd(struct dma_buf *dmabuf, int flags);
177 struct dma_buf *dma_buf_get(int fd);
178 void dma_buf_put(struct dma_buf *dmabuf);
179
180 struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *,
181 enum dma_data_direction);
182 void dma_buf_unmap_attachment(struct dma_buf_attachment *, struct sg_table *,
183 enum dma_data_direction);
184 int dma_buf_begin_cpu_access(struct dma_buf *dma_buf, size_t start, size_t len,
185 enum dma_data_direction dir);
186 void dma_buf_end_cpu_access(struct dma_buf *dma_buf, size_t start, size_t len,
187 enum dma_data_direction dir);
188 void *dma_buf_kmap_atomic(struct dma_buf *, unsigned long);
189 void dma_buf_kunmap_atomic(struct dma_buf *, unsigned long, void *);
190 void *dma_buf_kmap(struct dma_buf *, unsigned long);
191 void dma_buf_kunmap(struct dma_buf *, unsigned long, void *);
192
193 int dma_buf_mmap(struct dma_buf *, struct vm_area_struct *,
194 unsigned long);
195 void *dma_buf_vmap(struct dma_buf *);
196 void dma_buf_vunmap(struct dma_buf *, void *vaddr);
197 int dma_buf_debugfs_create_file(const char *name,
198 int (*write)(struct seq_file *));
199 #endif /* __DMA_BUF_H__ */
200