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 */ 54struct 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#define DMA_BUF_BASE 'b' 89#define DMA_BUF_IOCTL_SYNC _IOW(DMA_BUF_BASE, 0, struct dma_buf_sync) 90 91/* 32/64bitness of this uapi was botched in android, there's no difference 92 * between them in actual uapi, they're just different numbers. 93 */ 94#define DMA_BUF_SET_NAME _IOW(DMA_BUF_BASE, 1, const char *) 95#define DMA_BUF_SET_NAME_A _IOW(DMA_BUF_BASE, 1, u32) 96#define DMA_BUF_SET_NAME_B _IOW(DMA_BUF_BASE, 1, u64) 97 98#endif 99