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dma-buf.h
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/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ /* * Framework for buffer objects that can be shared across devices/subsystems. * * Copyright(C) 2015 Intel Ltd * * This program is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 as published by * the Free Software Foundation. * * This program is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for * more details. * * You should have received a copy of the GNU General Public License along with * this program. If not, see <http://www.gnu.org/licenses/>. */ #ifndef _DMA_BUF_UAPI_H_ #define _DMA_BUF_UAPI_H_ #include <linux/types.h> /* begin/end dma-buf functions used for userspace mmap. */ struct dma_buf_sync { __u64 flags; }; #define DMA_BUF_SYNC_READ (1 << 0) #define DMA_BUF_SYNC_WRITE (2 << 0) #define DMA_BUF_SYNC_RW (DMA_BUF_SYNC_READ | DMA_BUF_SYNC_WRITE) #define DMA_BUF_SYNC_START (0 << 2) #define DMA_BUF_SYNC_END (1 << 2) #define DMA_BUF_SYNC_VALID_FLAGS_MASK \ (DMA_BUF_SYNC_RW | DMA_BUF_SYNC_END) #define DMA_BUF_NAME_LEN 32 /** * struct dma_buf_export_sync_file - Get a sync_file from a dma-buf * * Userspace can perform a DMA_BUF_IOCTL_EXPORT_SYNC_FILE to retrieve the * current set of fences on a dma-buf file descriptor as a sync_file. CPU * waits via poll() or other driver-specific mechanisms typically wait on * whatever fences are on the dma-buf at the time the wait begins. This * is similar except that it takes a snapshot of the current fences on the * dma-buf for waiting later instead of waiting immediately. This is * useful for modern graphics APIs such as Vulkan which assume an explicit * synchronization model but still need to inter-operate with dma-buf. * * The intended usage pattern is the following: * * 1. Export a sync_file with flags corresponding to the expected GPU usage * via DMA_BUF_IOCTL_EXPORT_SYNC_FILE. * * 2. Submit rendering work which uses the dma-buf. The work should wait on * the exported sync file before rendering and produce another sync_file * when complete. * * 3. Import the rendering-complete sync_file into the dma-buf with flags * corresponding to the GPU usage via DMA_BUF_IOCTL_IMPORT_SYNC_FILE. * * Unlike doing implicit synchronization via a GPU kernel driver's exec ioctl, * the above is not a single atomic operation. If userspace wants to ensure * ordering via these fences, it is the respnosibility of userspace to use * locks or other mechanisms to ensure that no other context adds fences or * submits work between steps 1 and 3 above. */ struct dma_buf_export_sync_file { /** * @flags: Read/write flags * * Must be DMA_BUF_SYNC_READ, DMA_BUF_SYNC_WRITE, or both. * * If DMA_BUF_SYNC_READ is set and DMA_BUF_SYNC_WRITE is not set, * the returned sync file waits on any writers of the dma-buf to * complete. Waiting on the returned sync file is equivalent to * poll() with POLLIN. * * If DMA_BUF_SYNC_WRITE is set, the returned sync file waits on * any users of the dma-buf (read or write) to complete. Waiting * on the returned sync file is equivalent to poll() with POLLOUT. * If both DMA_BUF_SYNC_WRITE and DMA_BUF_SYNC_READ are set, this * is equivalent to just DMA_BUF_SYNC_WRITE. */ __u32 flags; /** @fd: Returned sync file descriptor */ __s32 fd; }; /** * struct dma_buf_import_sync_file - Insert a sync_file into a dma-buf * * Userspace can perform a DMA_BUF_IOCTL_IMPORT_SYNC_FILE to insert a * sync_file into a dma-buf for the purposes of implicit synchronization * with other dma-buf consumers. This allows clients using explicitly * synchronized APIs such as Vulkan to inter-op with dma-buf consumers * which expect implicit synchronization such as OpenGL or most media * drivers/video. */ struct dma_buf_import_sync_file { /** * @flags: Read/write flags * * Must be DMA_BUF_SYNC_READ, DMA_BUF_SYNC_WRITE, or both. * * If DMA_BUF_SYNC_READ is set and DMA_BUF_SYNC_WRITE is not set, * this inserts the sync_file as a read-only fence. Any subsequent * implicitly synchronized writes to this dma-buf will wait on this * fence but reads will not. * * If DMA_BUF_SYNC_WRITE is set, this inserts the sync_file as a * write fence. All subsequent implicitly synchronized access to * this dma-buf will wait on this fence. */ __u32 flags; /** @fd: Sync file descriptor */ __s32 fd; }; #define DMA_BUF_BASE 'b' #define DMA_BUF_IOCTL_SYNC _IOW(DMA_BUF_BASE, 0, struct dma_buf_sync) /* 32/64bitness of this uapi was botched in android, there's no difference * between them in actual uapi, they're just different numbers. */ #define DMA_BUF_SET_NAME _IOW(DMA_BUF_BASE, 1, const char *) #define DMA_BUF_SET_NAME_A _IOW(DMA_BUF_BASE, 1, __u32) #define DMA_BUF_SET_NAME_B _IOW(DMA_BUF_BASE, 1, __u64) #define DMA_BUF_IOCTL_EXPORT_SYNC_FILE _IOWR(DMA_BUF_BASE, 2, struct dma_buf_export_sync_file) #define DMA_BUF_IOCTL_IMPORT_SYNC_FILE _IOW(DMA_BUF_BASE, 3, struct dma_buf_import_sync_file) #endif