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Linux/include/linux/dma-buf.h

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  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  */
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 

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