drivers/virtio/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  */
  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  */
  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  */
  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  */
  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_DESCRIPTION("dma-bufs for virtio exported objects");
  89 MODULE_LICENSE("GPL");
  90 MODULE_IMPORT_NS(DMA_BUF);