virtio_dma_buf.c

 1// SPDX-License-Identifier: GPL-2.0-or-later
 2/*
 3 * dma-bufs for virtio exported objects
 4 *
 5 * Copyright (C) 2020 Google, Inc.
 6 */
 7
 8#include <linux/module.h>
 9#include <linux/virtio_dma_buf.h>
10
11/**
12 * virtio_dma_buf_export - Creates a new dma-buf for a virtio exported object
13 * @exp_info: [in] see dma_buf_export(). ops MUST refer to a dma_buf_ops
14 *	struct embedded in a virtio_dma_buf_ops.
15 *
16 * This wraps dma_buf_export() to allow virtio drivers to create a dma-buf
17 * for an virtio exported object that can be queried by other virtio drivers
18 * for the object's UUID.
19 */
20struct dma_buf *virtio_dma_buf_export
21	(const struct dma_buf_export_info *exp_info)
22{
23	const struct virtio_dma_buf_ops *virtio_ops =
24		container_of(exp_info->ops,
25			     const struct virtio_dma_buf_ops, ops);
26
27	if (!exp_info->ops ||
28	    exp_info->ops->attach != &virtio_dma_buf_attach ||
29	    !virtio_ops->get_uuid) {
30		return ERR_PTR(-EINVAL);
31	}
32
33	return dma_buf_export(exp_info);
34}
35EXPORT_SYMBOL(virtio_dma_buf_export);
36
37/**
38 * virtio_dma_buf_attach - mandatory attach callback for virtio dma-bufs
39 * @dma_buf: [in] buffer to attach
40 * @attach: [in] attachment structure
41 */
42int virtio_dma_buf_attach(struct dma_buf *dma_buf,
43			  struct dma_buf_attachment *attach)
44{
45	int ret;
46	const struct virtio_dma_buf_ops *ops =
47		container_of(dma_buf->ops,
48			     const struct virtio_dma_buf_ops, ops);
49
50	if (ops->device_attach) {
51		ret = ops->device_attach(dma_buf, attach);
52		if (ret)
53			return ret;
54	}
55	return 0;
56}
57EXPORT_SYMBOL(virtio_dma_buf_attach);
58
59/**
60 * is_virtio_dma_buf - returns true if the given dma-buf is a virtio dma-buf
61 * @dma_buf: buffer to query
62 */
63bool is_virtio_dma_buf(struct dma_buf *dma_buf)
64{
65	return dma_buf->ops->attach == &virtio_dma_buf_attach;
66}
67EXPORT_SYMBOL(is_virtio_dma_buf);
68
69/**
70 * virtio_dma_buf_get_uuid - gets a virtio dma-buf's exported object's uuid
71 * @dma_buf: [in] buffer to query
72 * @uuid: [out] the uuid
73 *
74 * Returns: 0 on success, negative on failure.
75 */
76int virtio_dma_buf_get_uuid(struct dma_buf *dma_buf,
77			    uuid_t *uuid)
78{
79	const struct virtio_dma_buf_ops *ops =
80		container_of(dma_buf->ops,
81			     const struct virtio_dma_buf_ops, ops);
82
83	if (!is_virtio_dma_buf(dma_buf))
84		return -EINVAL;
85
86	return ops->get_uuid(dma_buf, uuid);
87}
88EXPORT_SYMBOL(virtio_dma_buf_get_uuid);
89
90MODULE_DESCRIPTION("dma-bufs for virtio exported objects");
91MODULE_LICENSE("GPL");
92MODULE_IMPORT_NS("DMA_BUF");