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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 Ltd6 *7 * This program is free software; you can redistribute it and/or modify it8 * under the terms of the GNU General Public License version 2 as published by9 * the Free Software Foundation.10 *11 * This program is distributed in the hope that it will be useful, but WITHOUT12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for14 * more details.15 *16 * You should have received a copy of the GNU General Public License along with17 * 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 always29 * possible to guarantee coherency between the CPU-visible map and underlying30 * memory. To manage coherency, DMA_BUF_IOCTL_SYNC must be used to bracket31 * any CPU access to give the kernel the chance to shuffle memory around if32 * needed.33 *34 * Prior to accessing the map, the client must call DMA_BUF_IOCTL_SYNC35 * with DMA_BUF_SYNC_START and the appropriate read/write flags. Once the36 * access is complete, the client should call DMA_BUF_IOCTL_SYNC with37 * DMA_BUF_SYNC_END and the same read/write flags.38 *39 * The synchronization provided via DMA_BUF_IOCTL_SYNC only provides cache40 * coherency. It does not prevent other processes or devices from41 * accessing the memory at the same time. If synchronization with a GPU or42 * other device driver is required, it is the client's responsibility to43 * wait for buffer to be ready for reading or writing before calling this44 * ioctl with DMA_BUF_SYNC_START. Likewise, the client must ensure that45 * follow-up work is not submitted to GPU or other device driver until46 * 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 implicit49 * synchronization, waiting for prior work to complete can be done via50 * poll() on the DMA buffer file descriptor. If the driver or API requires51 * explicit synchronization, the client may have to wait on a sync_file or52 * other synchronization primitive outside the scope of the DMA buffer API.53 */54struct dma_buf_sync {55 /**56 * @flags: Set of access flags57 *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 the66 * client via the CPU map.67 *68 * DMA_BUF_SYNC_WRITE:69 * Indicates that the mapped DMA buffer will be written by the70 * 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 3287 88/**89 * struct dma_buf_export_sync_file - Get a sync_file from a dma-buf90 *91 * Userspace can perform a DMA_BUF_IOCTL_EXPORT_SYNC_FILE to retrieve the92 * current set of fences on a dma-buf file descriptor as a sync_file. CPU93 * waits via poll() or other driver-specific mechanisms typically wait on94 * whatever fences are on the dma-buf at the time the wait begins. This95 * is similar except that it takes a snapshot of the current fences on the96 * dma-buf for waiting later instead of waiting immediately. This is97 * useful for modern graphics APIs such as Vulkan which assume an explicit98 * 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 usage103 * via DMA_BUF_IOCTL_EXPORT_SYNC_FILE.104 *105 * 2. Submit rendering work which uses the dma-buf. The work should wait on106 * the exported sync file before rendering and produce another sync_file107 * when complete.108 *109 * 3. Import the rendering-complete sync_file into the dma-buf with flags110 * 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 ensure114 * ordering via these fences, it is the respnosibility of userspace to use115 * locks or other mechanisms to ensure that no other context adds fences or116 * submits work between steps 1 and 3 above.117 */118struct dma_buf_export_sync_file {119 /**120 * @flags: Read/write flags121 *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 to126 * complete. Waiting on the returned sync file is equivalent to127 * poll() with POLLIN.128 *129 * If DMA_BUF_SYNC_WRITE is set, the returned sync file waits on130 * any users of the dma-buf (read or write) to complete. Waiting131 * 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, this133 * 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-buf142 *143 * Userspace can perform a DMA_BUF_IOCTL_IMPORT_SYNC_FILE to insert a144 * sync_file into a dma-buf for the purposes of implicit synchronization145 * with other dma-buf consumers. This allows clients using explicitly146 * synchronized APIs such as Vulkan to inter-op with dma-buf consumers147 * which expect implicit synchronization such as OpenGL or most media148 * drivers/video.149 */150struct dma_buf_import_sync_file {151 /**152 * @flags: Read/write flags153 *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 subsequent158 * implicitly synchronized writes to this dma-buf will wait on this159 * fence but reads will not.160 *161 * If DMA_BUF_SYNC_WRITE is set, this inserts the sync_file as a162 * write fence. All subsequent implicitly synchronized access to163 * 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 difference174 * 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#endif183