1/*-
2 * SPDX-License-Identifier: BSD-2-Clause
3 *
4 * Copyright (c) 2012 Ian Lepore
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29/*
30 */
31
32/*
33 * A buffer pool manager, for use by a platform's busdma implementation.
34 */
35
36#ifndef _MACHINE_BUSDMA_BUFALLOC_H_
37#define _MACHINE_BUSDMA_BUFALLOC_H_
38
39#include <machine/bus.h>
40#include <vm/uma.h>
41
42/*
43 * Information about a buffer zone, returned by busdma_bufalloc_findzone().
44 */
45struct busdma_bufzone {
46 bus_size_t size;
47 uma_zone_t umazone;
48 char name[24];
49};
50
51/*
52 * Opaque handle type returned by busdma_bufalloc_create().
53 */
54struct busdma_bufalloc;
55typedef struct busdma_bufalloc *busdma_bufalloc_t;
56
57/*
58 * Create an allocator that manages a pool of DMA buffers.
59 *
60 * The allocator manages a collection of uma(9) zones of buffers in power-of-two
61 * sized increments ranging from minimum_alignment to the platform's PAGE_SIZE.
62 * The buffers within each zone are aligned on boundaries corresponding to the
63 * buffer size, and thus by implication each buffer is contiguous within a page
64 * and does not cross a power of two boundary larger than the buffer size.
65 * These rules are intended to make it easy for a busdma implementation to
66 * check whether a tag's constraints allow use of a buffer from the allocator.
67 *
68 * minimum_alignment is also the minimum buffer allocation size. For platforms
69 * with software-assisted cache coherency, this is typically the data cache line
70 * size (and MUST not be smaller than the cache line size).
71 *
72 * name appears in zone stats as 'dma name nnnnn' where 'dma' is fixed and
73 * 'nnnnn' is the size of buffers in that zone.
74 *
75 * If the alloc/free function pointers are NULL, the regular uma internal
76 * allocators are used (I.E., you get "plain old kernel memory"). On a platform
77 * with an exclusion zone that applies to all DMA operations, a custom allocator
78 * could be used to ensure no buffer memory is ever allocated from that zone,
79 * allowing the bus_dmamem_alloc() implementation to make the assumption that
80 * buffers provided by the allocation could never lead to the need for a bounce.
81 */
82busdma_bufalloc_t busdma_bufalloc_create(const char *name,
83 bus_size_t minimum_alignment,
84 uma_alloc uma_alloc_func, uma_free uma_free_func,
85 u_int32_t uma_zcreate_flags);
86
87/*
88 * Destroy an allocator created by busdma_bufalloc_create().
89 * Safe to call with a NULL pointer.
90 */
91void busdma_bufalloc_destroy(busdma_bufalloc_t ba);
92
93/*
94 * Return a pointer to the busdma_bufzone that should be used to allocate or
95 * free a buffer of the given size. Returns NULL if the size is larger than the
96 * largest zone handled by the allocator.
97 */
98struct busdma_bufzone * busdma_bufalloc_findzone(busdma_bufalloc_t ba,
99 bus_size_t size);
100
101/*
102 * These built-in allocation routines are available for managing a pools of
103 * uncacheable memory on platforms that support VM_MEMATTR_UNCACHEABLE.
104 *
105 * Allocation is done using kmem_alloc_attr() with these parameters:
106 * lowaddr = 0
107 * highaddr = BUS_SPACE_MAXADDR
108 * memattr = VM_MEMATTR_UNCACHEABLE.
109 *
110 * If your platform has no exclusion region (lowaddr/highaddr), and its pmap
111 * routines support pmap_page_set_memattr() and the VM_MEMATTR_UNCACHEABLE flag
112 * you can probably use these when you need uncacheable buffers.
113 */
114void * busdma_bufalloc_alloc_uncacheable(uma_zone_t zone, vm_size_t size,
115 int domain, uint8_t *pflag, int wait);
116void busdma_bufalloc_free_uncacheable(void *item, vm_size_t size,
117 uint8_t pflag);
118
119#endif /* _MACHINE_BUSDMA_BUFALLOC_H_ */