This framework allows a unified userspace interface for dma-buf exporters, allowing userland to allocate specific types of memory for use in dma-buf sharing. Each heap is given its own device node, which a user can allocate a dma-buf fd from using the DMA_HEAP_IOC_ALLOC. This code is an evoluiton of the Android ION implementation, and a big thanks is due to its authors/maintainers over time for their effort: Rebecca Schultz Zavin, Colin Cross, Benjamin Gaignard, Laura Abbott, and many other contributors!
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| 1 | +/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ | |
| 2 | +/* | |
| 3 | + * DMABUF Heaps Userspace API | |
| 4 | + * | |
| 5 | + * Copyright (C) 2011 Google, Inc. | |
| 6 | + * Copyright (C) 2019 Linaro Ltd. | |
| 7 | + */ | |
| 8 | +#ifndef _UAPI_LINUX_DMABUF_POOL_H | |
| 9 | +#define _UAPI_LINUX_DMABUF_POOL_H | |
| 10 | + | |
| 11 | +#include <linux/ioctl.h> | |
| 12 | +#include <linux/types.h> | |
| 13 | + | |
| 14 | +/** | |
| 15 | + * DOC: DMABUF Heaps Userspace API | |
| 16 | + */ | |
| 17 | + | |
| 18 | +/* Valid FD_FLAGS are O_CLOEXEC, O_RDONLY, O_WRONLY, O_RDWR */ | |
| 19 | +#define DMA_HEAP_VALID_FD_FLAGS (O_CLOEXEC | O_ACCMODE) | |
| 20 | + | |
| 21 | +/* Currently no heap flags */ | |
| 22 | +#define DMA_HEAP_VALID_HEAP_FLAGS (0) | |
| 23 | + | |
| 24 | +/** | |
| 25 | + * struct dma_heap_allocation_data - metadata passed from userspace for | |
| 26 | + * allocations | |
| 27 | + * @len: size of the allocation | |
| 28 | + * @fd: will be populated with a fd which provdes the | |
| 29 | + * handle to the allocated dma-buf | |
| 30 | + * @fd_flags: file descriptor flags used when allocating | |
| 31 | + * @heap_flags: flags passed to heap | |
| 32 | + * | |
| 33 | + * Provided by userspace as an argument to the ioctl | |
| 34 | + */ | |
| 35 | +struct dma_heap_allocation_data { | |
| 36 | + __u64 len; | |
| 37 | + __u32 fd; | |
| 38 | + __u32 fd_flags; | |
| 39 | + __u64 heap_flags; | |
| 40 | + __u32 reserved0; | |
| 41 | + __u32 reserved1; | |
| 42 | +}; | |
| 43 | + | |
| 44 | +#define DMA_HEAP_IOC_MAGIC 'H' | |
| 45 | + | |
| 46 | +/** | |
| 47 | + * DOC: DMA_HEAP_IOC_ALLOC - allocate memory from pool | |
| 48 | + * | |
| 49 | + * Takes an dma_heap_allocation_data struct and returns it with the fd field | |
| 50 | + * populated with the dmabuf handle of the allocation. | |
| 51 | + */ | |
| 52 | +#define DMA_HEAP_IOC_ALLOC _IOWR(DMA_HEAP_IOC_MAGIC, 0, \ | |
| 53 | + struct dma_heap_allocation_data) | |
| 54 | + | |
| 55 | +#endif /* _UAPI_LINUX_DMABUF_POOL_H */ | |