source: mainline/uspace/lib/usbhost/include/usb/host/dma_buffer.h@ cfe4852

lfn serial ticket/834-toolchain-update topic/msim-upgrade topic/simplify-dev-export
Last change on this file since cfe4852 was cfe4852, checked in by Aearsis <Hlavaty.Ondrej@…>, 8 years ago

usbhost: introduce dma_buffer

Dma buffers shall simplify management of bounce buffers, eliminating the
errors of using malloc/malloc32, avoiding addr_to_phys.

The alloc function can be passed a policy to influence alignment and
flags. This will be used in future by xhci to allow bounce buffers
outside the lower 32b of addressable space, if the hardware supports it.

Also, the buffers are written with particular extension in mind: memory
pools. In previous HCs, there are a lot of situations where
significantly smaller buffer then PAGE_SIZE is needed, yet a page needs
to be allocated. We could solve this issue by building an allocator on
top of dma-available memory.

  • Property mode set to 100644
File size: 2.5 KB
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1/*
2 * Copyright (c) 2017 Ondrej Hlavaty <aearsis@eideo.cz>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 *
9 * - Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * - Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 * - The name of the author may not be used to endorse or promote products
15 * derived from this software without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 */
28/** @addtogroup drvusbehci
29 * @{
30 */
31/** @file
32 * @brief USB host controller library: DMA buffer helpers
33 *
34 * Simplifies usage of bounce buffers.
35 *
36 * Currently the minimum size allocated is a page, which is wasteful. Could be
37 * extended to support memory pools, which will enable smaller units of
38 * allocation.
39 */
40#ifndef LIB_USBHOST_DMA_BUFFER
41#define LIB_USBHOST_DMA_BUFFER
42
43#include <stdint.h>
44#include <stdlib.h>
45#include <errno.h>
46
47typedef const struct dma_policy {
48 bool use64; /**< Whether to use more than initial 4GiB of memory */
49 size_t alignment; /**< What alignment is needed. At most PAGE_SIZE. */
50} dma_policy_t;
51
52typedef struct dma_buffer {
53 void *virt;
54 uintptr_t phys;
55} dma_buffer_t;
56
57extern dma_policy_t dma_policy_default;
58
59extern int dma_buffer_alloc(dma_buffer_t *db, size_t size);
60extern int dma_buffer_alloc_policy(dma_buffer_t *, size_t, dma_policy_t);
61extern void dma_buffer_free(dma_buffer_t *);
62
63static inline int dma_buffer_is_set(dma_buffer_t *db)
64{
65 return !!db->virt;
66}
67
68#endif
69/**
70 * @}
71 */
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