2 * Header file for dma buffer sharing framework.
4 * Copyright(C) 2011 Linaro Limited. All rights reserved.
5 * Author: Sumit Semwal <sumit.semwal@ti.com>
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.
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.
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
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/>.
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>
33 #include <linux/dma-fence.h>
34 #include <linux/wait.h>
38 struct dma_buf_attachment;
41 * struct dma_buf_ops - operations possible on struct dma_buf
42 * @attach: [optional] allows different devices to 'attach' themselves to the
43 * given buffer. It might return -EBUSY to signal that backing storage
44 * is already allocated and incompatible with the requirements
45 * of requesting device.
46 * @detach: [optional] detach a given device from this buffer.
47 * @map_dma_buf: returns list of scatter pages allocated, increases usecount
48 * of the buffer. Requires atleast one attach to be called
49 * before. Returned sg list should already be mapped into
50 * _device_ address space. This call may sleep. May also return
51 * -EINTR. Should return -EINVAL if attach hasn't been called yet.
52 * @unmap_dma_buf: decreases usecount of buffer, might deallocate scatter
54 * @release: release this buffer; to be called after the last dma_buf_put.
55 * @begin_cpu_access: [optional] called before cpu access to invalidate cpu
56 * caches and allocate backing storage (if not yet done)
57 * respectively pin the object into memory.
58 * @end_cpu_access: [optional] called after cpu access to flush caches.
59 * @kmap_atomic: maps a page from the buffer into kernel address
60 * space, users may not block until the subsequent unmap call.
61 * This callback must not sleep.
62 * @kunmap_atomic: [optional] unmaps a atomically mapped page from the buffer.
63 * This Callback must not sleep.
64 * @kmap: maps a page from the buffer into kernel address space.
65 * @kunmap: [optional] unmaps a page from the buffer.
66 * @mmap: used to expose the backing storage to userspace. Note that the
67 * mapping needs to be coherent - if the exporter doesn't directly
68 * support this, it needs to fake coherency by shooting down any ptes
69 * when transitioning away from the cpu domain.
70 * @vmap: [optional] creates a virtual mapping for the buffer into kernel
71 * address space. Same restrictions as for vmap and friends apply.
72 * @vunmap: [optional] unmaps a vmap from the buffer
75 int (*attach)(struct dma_buf *, struct device *,
76 struct dma_buf_attachment *);
78 void (*detach)(struct dma_buf *, struct dma_buf_attachment *);
80 /* For {map,unmap}_dma_buf below, any specific buffer attributes
81 * required should get added to device_dma_parameters accessible
82 * via dev->dma_params.
84 struct sg_table * (*map_dma_buf)(struct dma_buf_attachment *,
85 enum dma_data_direction);
86 void (*unmap_dma_buf)(struct dma_buf_attachment *,
88 enum dma_data_direction);
89 /* TODO: Add try_map_dma_buf version, to return immed with -EBUSY
90 * if the call would block.
93 /* after final dma_buf_put() */
94 void (*release)(struct dma_buf *);
96 int (*begin_cpu_access)(struct dma_buf *, enum dma_data_direction);
97 int (*end_cpu_access)(struct dma_buf *, 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 *);
103 int (*mmap)(struct dma_buf *, struct vm_area_struct *vma);
105 void *(*vmap)(struct dma_buf *);
106 void (*vunmap)(struct dma_buf *, void *vaddr);
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 * @lock: used internally to serialize list manipulation, attach/detach and vmap/unmap
116 * @vmapping_counter: used internally to refcnt the vmaps
117 * @vmap_ptr: the current vmap ptr if vmapping_counter > 0
118 * @exp_name: name of the exporter; useful for debugging.
119 * @owner: pointer to exporter module; used for refcounting when exporter is a
121 * @list_node: node for dma_buf accounting and debugging.
122 * @priv: exporter specific private data for this buffer object.
123 * @resv: reservation object linked to this dma-buf
124 * @poll: for userspace poll support
125 * @cb_excl: for userspace poll support
126 * @cb_shared: for userspace poll support
131 struct list_head attachments;
132 const struct dma_buf_ops *ops;
134 unsigned vmapping_counter;
136 const char *exp_name;
137 struct module *owner;
138 struct list_head list_node;
140 struct reservation_object *resv;
143 wait_queue_head_t poll;
145 struct dma_buf_poll_cb_t {
146 struct dma_fence_cb cb;
147 wait_queue_head_t *poll;
149 unsigned long active;
150 } cb_excl, cb_shared;
154 * struct dma_buf_attachment - holds device-buffer attachment data
155 * @dmabuf: buffer for this attachment.
156 * @dev: device attached to the buffer.
157 * @node: list of dma_buf_attachment.
158 * @priv: exporter specific attachment data.
160 * This structure holds the attachment information between the dma_buf buffer
161 * and its user device(s). The list contains one attachment struct per device
162 * attached to the buffer.
164 struct dma_buf_attachment {
165 struct dma_buf *dmabuf;
167 struct list_head node;
172 * struct dma_buf_export_info - holds information needed to export a dma_buf
173 * @exp_name: name of the exporter - useful for debugging.
174 * @owner: pointer to exporter module - used for refcounting kernel module
175 * @ops: Attach allocator-defined dma buf ops to the new buffer
176 * @size: Size of the buffer
177 * @flags: mode flags for the file
178 * @resv: reservation-object, NULL to allocate default one
179 * @priv: Attach private data of allocator to this buffer
181 * This structure holds the information required to export the buffer. Used
182 * with dma_buf_export() only.
184 struct dma_buf_export_info {
185 const char *exp_name;
186 struct module *owner;
187 const struct dma_buf_ops *ops;
190 struct reservation_object *resv;
195 * helper macro for exporters; zeros and fills in most common values
197 * @name: export-info name
199 #define DEFINE_DMA_BUF_EXPORT_INFO(name) \
200 struct dma_buf_export_info name = { .exp_name = KBUILD_MODNAME, \
201 .owner = THIS_MODULE }
204 * get_dma_buf - convenience wrapper for get_file.
205 * @dmabuf: [in] pointer to dma_buf
207 * Increments the reference count on the dma-buf, needed in case of drivers
208 * that either need to create additional references to the dmabuf on the
209 * kernel side. For example, an exporter that needs to keep a dmabuf ptr
210 * so that subsequent exports don't create a new dmabuf.
212 static inline void get_dma_buf(struct dma_buf *dmabuf)
214 get_file(dmabuf->file);
217 struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,
219 void dma_buf_detach(struct dma_buf *dmabuf,
220 struct dma_buf_attachment *dmabuf_attach);
222 struct dma_buf *dma_buf_export(const struct dma_buf_export_info *exp_info);
224 int dma_buf_fd(struct dma_buf *dmabuf, int flags);
225 struct dma_buf *dma_buf_get(int fd);
226 void dma_buf_put(struct dma_buf *dmabuf);
228 struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *,
229 enum dma_data_direction);
230 void dma_buf_unmap_attachment(struct dma_buf_attachment *, struct sg_table *,
231 enum dma_data_direction);
232 int dma_buf_begin_cpu_access(struct dma_buf *dma_buf,
233 enum dma_data_direction dir);
234 int dma_buf_end_cpu_access(struct dma_buf *dma_buf,
235 enum dma_data_direction dir);
236 void *dma_buf_kmap_atomic(struct dma_buf *, unsigned long);
237 void dma_buf_kunmap_atomic(struct dma_buf *, unsigned long, void *);
238 void *dma_buf_kmap(struct dma_buf *, unsigned long);
239 void dma_buf_kunmap(struct dma_buf *, unsigned long, void *);
241 int dma_buf_mmap(struct dma_buf *, struct vm_area_struct *,
243 void *dma_buf_vmap(struct dma_buf *);
244 void dma_buf_vunmap(struct dma_buf *, void *vaddr);
245 #endif /* __DMA_BUF_H__ */