The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/sys/busdma_bufalloc.h

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    1 /*-
    2  * Copyright (c) 2012 Ian Lepore
    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  * 1. Redistributions of source code must retain the above copyright
    9  *    notice, this list of conditions and the following disclaimer.
   10  * 2. Redistributions in binary form must reproduce the above copyright
   11  *    notice, this list of conditions and the following disclaimer in the
   12  *    documentation and/or other materials provided with the distribution.
   13  *
   14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   24  * SUCH DAMAGE.
   25  */
   26 
   27 /*
   28  * $FreeBSD: stable/9/sys/sys/busdma_bufalloc.h 251871 2013-06-17 21:41:14Z scottl $
   29  */
   30 
   31 /*
   32  * A buffer pool manager, for use by a platform's busdma implementation.
   33  */
   34 
   35 #ifndef _MACHINE_BUSDMA_BUFALLOC_H_
   36 #define _MACHINE_BUSDMA_BUFALLOC_H_
   37 
   38 #include <machine/bus.h>
   39 #include <vm/uma.h>
   40 
   41 /*
   42  * Information about a buffer zone, returned by busdma_bufalloc_findzone().
   43  */
   44 struct busdma_bufzone {
   45         bus_size_t      size;
   46         uma_zone_t      umazone;
   47         char            name[24];
   48 };
   49 
   50 /*
   51  * Opaque handle type returned by busdma_bufalloc_create().
   52  */
   53 struct busdma_bufalloc;
   54 typedef struct busdma_bufalloc *busdma_bufalloc_t;
   55 
   56 /*
   57  * Create an allocator that manages a pool of DMA buffers.
   58  *
   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.
   66  *
   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).
   70  *
   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.
   73  *
   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.
   80  */
   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);
   85 
   86 /*
   87  * Destroy an allocator created by busdma_bufalloc_create().
   88  * Safe to call with a NULL pointer.
   89  */
   90 void busdma_bufalloc_destroy(busdma_bufalloc_t ba);
   91 
   92 /*
   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.
   96  */
   97 struct busdma_bufzone * busdma_bufalloc_findzone(busdma_bufalloc_t ba,
   98     bus_size_t size);
   99 
  100 /*
  101  * These built-in allocation routines are available for managing a pools of
  102  * uncacheable memory on platforms that support VM_MEMATTR_UNCACHEABLE.
  103  *
  104  * Allocation is done using kmem_alloc_attr() with these parameters:
  105  *   lowaddr  = 0
  106  *   highaddr = BUS_SPACE_MAXADDR
  107  *   memattr  = VM_MEMATTR_UNCACHEABLE.
  108  *
  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.
  112  */
  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);
  116 
  117 #endif  /* _MACHINE_BUSDMA_BUFALLOC_H_ */
  118 

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