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_ */