1 | /* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ |
2 | /* |
3 | * Framework for buffer objects that can be shared across devices/subsystems. |
4 | * |
5 | * Copyright(C) 2015 Intel Ltd |
6 | * |
7 | * This program is free software; you can redistribute it and/or modify it |
8 | * under the terms of the GNU General Public License version 2 as published by |
9 | * the Free Software Foundation. |
10 | * |
11 | * This program is distributed in the hope that it will be useful, but WITHOUT |
12 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
13 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for |
14 | * more details. |
15 | * |
16 | * You should have received a copy of the GNU General Public License along with |
17 | * this program. If not, see <http://www.gnu.org/licenses/>. |
18 | */ |
19 | |
20 | #ifndef _DMA_BUF_UAPI_H_ |
21 | #define _DMA_BUF_UAPI_H_ |
22 | |
23 | #include <linux/types.h> |
24 | |
25 | /** |
26 | * struct dma_buf_sync - Synchronize with CPU access. |
27 | * |
28 | * When a DMA buffer is accessed from the CPU via mmap, it is not always |
29 | * possible to guarantee coherency between the CPU-visible map and underlying |
30 | * memory. To manage coherency, DMA_BUF_IOCTL_SYNC must be used to bracket |
31 | * any CPU access to give the kernel the chance to shuffle memory around if |
32 | * needed. |
33 | * |
34 | * Prior to accessing the map, the client must call DMA_BUF_IOCTL_SYNC |
35 | * with DMA_BUF_SYNC_START and the appropriate read/write flags. Once the |
36 | * access is complete, the client should call DMA_BUF_IOCTL_SYNC with |
37 | * DMA_BUF_SYNC_END and the same read/write flags. |
38 | * |
39 | * The synchronization provided via DMA_BUF_IOCTL_SYNC only provides cache |
40 | * coherency. It does not prevent other processes or devices from |
41 | * accessing the memory at the same time. If synchronization with a GPU or |
42 | * other device driver is required, it is the client's responsibility to |
43 | * wait for buffer to be ready for reading or writing before calling this |
44 | * ioctl with DMA_BUF_SYNC_START. Likewise, the client must ensure that |
45 | * follow-up work is not submitted to GPU or other device driver until |
46 | * after this ioctl has been called with DMA_BUF_SYNC_END? |
47 | * |
48 | * If the driver or API with which the client is interacting uses implicit |
49 | * synchronization, waiting for prior work to complete can be done via |
50 | * poll() on the DMA buffer file descriptor. If the driver or API requires |
51 | * explicit synchronization, the client may have to wait on a sync_file or |
52 | * other synchronization primitive outside the scope of the DMA buffer API. |
53 | */ |
54 | struct dma_buf_sync { |
55 | /** |
56 | * @flags: Set of access flags |
57 | * |
58 | * DMA_BUF_SYNC_START: |
59 | * Indicates the start of a map access session. |
60 | * |
61 | * DMA_BUF_SYNC_END: |
62 | * Indicates the end of a map access session. |
63 | * |
64 | * DMA_BUF_SYNC_READ: |
65 | * Indicates that the mapped DMA buffer will be read by the |
66 | * client via the CPU map. |
67 | * |
68 | * DMA_BUF_SYNC_WRITE: |
69 | * Indicates that the mapped DMA buffer will be written by the |
70 | * client via the CPU map. |
71 | * |
72 | * DMA_BUF_SYNC_RW: |
73 | * An alias for DMA_BUF_SYNC_READ | DMA_BUF_SYNC_WRITE. |
74 | */ |
75 | __u64 flags; |
76 | }; |
77 | |
78 | #define DMA_BUF_SYNC_READ (1 << 0) |
79 | #define DMA_BUF_SYNC_WRITE (2 << 0) |
80 | #define DMA_BUF_SYNC_RW (DMA_BUF_SYNC_READ | DMA_BUF_SYNC_WRITE) |
81 | #define DMA_BUF_SYNC_START (0 << 2) |
82 | #define DMA_BUF_SYNC_END (1 << 2) |
83 | #define DMA_BUF_SYNC_VALID_FLAGS_MASK \ |
84 | (DMA_BUF_SYNC_RW | DMA_BUF_SYNC_END) |
85 | |
86 | #define DMA_BUF_NAME_LEN 32 |
87 | |
88 | /** |
89 | * struct dma_buf_export_sync_file - Get a sync_file from a dma-buf |
90 | * |
91 | * Userspace can perform a DMA_BUF_IOCTL_EXPORT_SYNC_FILE to retrieve the |
92 | * current set of fences on a dma-buf file descriptor as a sync_file. CPU |
93 | * waits via poll() or other driver-specific mechanisms typically wait on |
94 | * whatever fences are on the dma-buf at the time the wait begins. This |
95 | * is similar except that it takes a snapshot of the current fences on the |
96 | * dma-buf for waiting later instead of waiting immediately. This is |
97 | * useful for modern graphics APIs such as Vulkan which assume an explicit |
98 | * synchronization model but still need to inter-operate with dma-buf. |
99 | * |
100 | * The intended usage pattern is the following: |
101 | * |
102 | * 1. Export a sync_file with flags corresponding to the expected GPU usage |
103 | * via DMA_BUF_IOCTL_EXPORT_SYNC_FILE. |
104 | * |
105 | * 2. Submit rendering work which uses the dma-buf. The work should wait on |
106 | * the exported sync file before rendering and produce another sync_file |
107 | * when complete. |
108 | * |
109 | * 3. Import the rendering-complete sync_file into the dma-buf with flags |
110 | * corresponding to the GPU usage via DMA_BUF_IOCTL_IMPORT_SYNC_FILE. |
111 | * |
112 | * Unlike doing implicit synchronization via a GPU kernel driver's exec ioctl, |
113 | * the above is not a single atomic operation. If userspace wants to ensure |
114 | * ordering via these fences, it is the respnosibility of userspace to use |
115 | * locks or other mechanisms to ensure that no other context adds fences or |
116 | * submits work between steps 1 and 3 above. |
117 | */ |
118 | struct dma_buf_export_sync_file { |
119 | /** |
120 | * @flags: Read/write flags |
121 | * |
122 | * Must be DMA_BUF_SYNC_READ, DMA_BUF_SYNC_WRITE, or both. |
123 | * |
124 | * If DMA_BUF_SYNC_READ is set and DMA_BUF_SYNC_WRITE is not set, |
125 | * the returned sync file waits on any writers of the dma-buf to |
126 | * complete. Waiting on the returned sync file is equivalent to |
127 | * poll() with POLLIN. |
128 | * |
129 | * If DMA_BUF_SYNC_WRITE is set, the returned sync file waits on |
130 | * any users of the dma-buf (read or write) to complete. Waiting |
131 | * on the returned sync file is equivalent to poll() with POLLOUT. |
132 | * If both DMA_BUF_SYNC_WRITE and DMA_BUF_SYNC_READ are set, this |
133 | * is equivalent to just DMA_BUF_SYNC_WRITE. |
134 | */ |
135 | __u32 flags; |
136 | /** @fd: Returned sync file descriptor */ |
137 | __s32 fd; |
138 | }; |
139 | |
140 | /** |
141 | * struct dma_buf_import_sync_file - Insert a sync_file into a dma-buf |
142 | * |
143 | * Userspace can perform a DMA_BUF_IOCTL_IMPORT_SYNC_FILE to insert a |
144 | * sync_file into a dma-buf for the purposes of implicit synchronization |
145 | * with other dma-buf consumers. This allows clients using explicitly |
146 | * synchronized APIs such as Vulkan to inter-op with dma-buf consumers |
147 | * which expect implicit synchronization such as OpenGL or most media |
148 | * drivers/video. |
149 | */ |
150 | struct dma_buf_import_sync_file { |
151 | /** |
152 | * @flags: Read/write flags |
153 | * |
154 | * Must be DMA_BUF_SYNC_READ, DMA_BUF_SYNC_WRITE, or both. |
155 | * |
156 | * If DMA_BUF_SYNC_READ is set and DMA_BUF_SYNC_WRITE is not set, |
157 | * this inserts the sync_file as a read-only fence. Any subsequent |
158 | * implicitly synchronized writes to this dma-buf will wait on this |
159 | * fence but reads will not. |
160 | * |
161 | * If DMA_BUF_SYNC_WRITE is set, this inserts the sync_file as a |
162 | * write fence. All subsequent implicitly synchronized access to |
163 | * this dma-buf will wait on this fence. |
164 | */ |
165 | __u32 flags; |
166 | /** @fd: Sync file descriptor */ |
167 | __s32 fd; |
168 | }; |
169 | |
170 | #define DMA_BUF_BASE 'b' |
171 | #define DMA_BUF_IOCTL_SYNC _IOW(DMA_BUF_BASE, 0, struct dma_buf_sync) |
172 | |
173 | /* 32/64bitness of this uapi was botched in android, there's no difference |
174 | * between them in actual uapi, they're just different numbers. |
175 | */ |
176 | #define DMA_BUF_SET_NAME _IOW(DMA_BUF_BASE, 1, const char *) |
177 | #define DMA_BUF_SET_NAME_A _IOW(DMA_BUF_BASE, 1, __u32) |
178 | #define DMA_BUF_SET_NAME_B _IOW(DMA_BUF_BASE, 1, __u64) |
179 | #define DMA_BUF_IOCTL_EXPORT_SYNC_FILE _IOWR(DMA_BUF_BASE, 2, struct dma_buf_export_sync_file) |
180 | #define DMA_BUF_IOCTL_IMPORT_SYNC_FILE _IOW(DMA_BUF_BASE, 3, struct dma_buf_import_sync_file) |
181 | |
182 | #endif |
183 | |