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 */ | ||