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  */
virtio_dma_buf_export(const struct dma_buf_export_info * exp_info)20 struct 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 }
35 EXPORT_SYMBOL(virtio_dma_buf_export);
36 
37 /**
38  * virtio_dma_buf_attach - mandatory attach callback for virtio dma-bufs
39  */
virtio_dma_buf_attach(struct dma_buf * dma_buf,struct dma_buf_attachment * attach)40 int virtio_dma_buf_attach(struct dma_buf *dma_buf,
41 			  struct dma_buf_attachment *attach)
42 {
43 	int ret;
44 	const struct virtio_dma_buf_ops *ops =
45 		container_of(dma_buf->ops,
46 			     const struct virtio_dma_buf_ops, ops);
47 
48 	if (ops->device_attach) {
49 		ret = ops->device_attach(dma_buf, attach);
50 		if (ret)
51 			return ret;
52 	}
53 	return 0;
54 }
55 EXPORT_SYMBOL(virtio_dma_buf_attach);
56 
57 /**
58  * is_virtio_dma_buf - returns true if the given dma-buf is a virtio dma-buf
59  * @dma_buf: buffer to query
60  */
is_virtio_dma_buf(struct dma_buf * dma_buf)61 bool is_virtio_dma_buf(struct dma_buf *dma_buf)
62 {
63 	return dma_buf->ops->attach == &virtio_dma_buf_attach;
64 }
65 EXPORT_SYMBOL(is_virtio_dma_buf);
66 
67 /**
68  * virtio_dma_buf_get_uuid - gets a virtio dma-buf's exported object's uuid
69  * @dma_buf: [in] buffer to query
70  * @uuid: [out] the uuid
71  *
72  * Returns: 0 on success, negative on failure.
73  */
virtio_dma_buf_get_uuid(struct dma_buf * dma_buf,uuid_t * uuid)74 int virtio_dma_buf_get_uuid(struct dma_buf *dma_buf,
75 			    uuid_t *uuid)
76 {
77 	const struct virtio_dma_buf_ops *ops =
78 		container_of(dma_buf->ops,
79 			     const struct virtio_dma_buf_ops, ops);
80 
81 	if (!is_virtio_dma_buf(dma_buf))
82 		return -EINVAL;
83 
84 	return ops->get_uuid(dma_buf, uuid);
85 }
86 EXPORT_SYMBOL(virtio_dma_buf_get_uuid);
87 
88 MODULE_LICENSE("GPL");
89 MODULE_IMPORT_NS(DMA_BUF);
90