2 * Copyright (c) 2012 Ian Lepore
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6 * modification, are permitted provided that the following conditions
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32 * A buffer pool manager, for use by a platform's busdma implementation.
35 #ifndef _MACHINE_BUSDMA_BUFALLOC_H_
36 #define _MACHINE_BUSDMA_BUFALLOC_H_
38 #include <machine/bus.h>
42 * Information about a buffer zone, returned by busdma_bufalloc_findzone().
44 struct busdma_bufzone {
51 * Opaque handle type returned by busdma_bufalloc_create().
53 struct busdma_bufalloc;
54 typedef struct busdma_bufalloc *busdma_bufalloc_t;
57 * Create an allocator that manages a pool of DMA buffers.
59 * The allocator manages a collection of uma(9) zones of buffers in power-of-two
60 * sized increments ranging from minimum_alignment to the platform's PAGE_SIZE.
61 * The buffers within each zone are aligned on boundaries corresponding to the
62 * buffer size, and thus by implication each buffer is contiguous within a page
63 * and does not cross a power of two boundary larger than the buffer size.
64 * These rules are intended to make it easy for a busdma implementation to
65 * check whether a tag's constraints allow use of a buffer from the allocator.
67 * minimum_alignment is also the minimum buffer allocation size. For platforms
68 * with software-assisted cache coherency, this is typically the data cache line
69 * size (and MUST not be smaller than the cache line size).
71 * name appears in zone stats as 'dma name nnnnn' where 'dma' is fixed and
72 * 'nnnnn' is the size of buffers in that zone.
74 * If if the alloc/free function pointers are NULL, the regular uma internal
75 * allocators are used (I.E., you get "plain old kernel memory"). On a platform
76 * with an exclusion zone that applies to all DMA operations, a custom allocator
77 * could be used to ensure no buffer memory is ever allocated from that zone,
78 * allowing the bus_dmamem_alloc() implementation to make the assumption that
79 * buffers provided by the allocation could never lead to the need for a bounce.
81 busdma_bufalloc_t busdma_bufalloc_create(const char *name,
82 bus_size_t minimum_alignment,
83 uma_alloc uma_alloc_func, uma_free uma_free_func,
84 u_int32_t uma_zcreate_flags);
87 * Destroy an allocator created by busdma_bufalloc_create().
88 * Safe to call with a NULL pointer.
90 void busdma_bufalloc_destroy(busdma_bufalloc_t ba);
93 * Return a pointer to the busdma_bufzone that should be used to allocate or
94 * free a buffer of the given size. Returns NULL if the size is larger than the
95 * largest zone handled by the allocator.
97 struct busdma_bufzone * busdma_bufalloc_findzone(busdma_bufalloc_t ba,
101 * These built-in allocation routines are available for managing a pools of
102 * uncacheable memory on platforms that support VM_MEMATTR_UNCACHEABLE.
104 * Allocation is done using kmem_alloc_attr() with these parameters:
106 * highaddr = BUS_SPACE_MAXADDR
107 * memattr = VM_MEMATTR_UNCACHEABLE.
109 * If your platform has no exclusion region (lowaddr/highaddr), and its pmap
110 * routines support pmap_page_set_memattr() and the VM_MEMATTR_UNCACHEABLE flag
111 * you can probably use these when you need uncacheable buffers.
113 void * busdma_bufalloc_alloc_uncacheable(uma_zone_t zone, int size,
114 u_int8_t *pflag, int wait);
115 void busdma_bufalloc_free_uncacheable(void *item, int size, u_int8_t pflag);
117 #endif /* _MACHINE_BUSDMA_BUFALLOC_H_ */