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  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
    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  * $FreeBSD: head/sys/sys/busdma_bufalloc.h 327903 2018-01-12 23:41:12Z jeff $
   31  */
   32 
   33 /*
   34  * A buffer pool manager, for use by a platform's busdma implementation.
   35  */
   36 
   37 #ifndef _MACHINE_BUSDMA_BUFALLOC_H_
   38 #define _MACHINE_BUSDMA_BUFALLOC_H_
   39 
   40 #include <machine/bus.h>
   41 #include <vm/uma.h>
   42 
   43 /*
   44  * Information about a buffer zone, returned by busdma_bufalloc_findzone().
   45  */
   46 struct busdma_bufzone {
   47         bus_size_t      size;
   48         uma_zone_t      umazone;
   49         char            name[24];
   50 };
   51 
   52 /*
   53  * Opaque handle type returned by busdma_bufalloc_create().
   54  */
   55 struct busdma_bufalloc;
   56 typedef struct busdma_bufalloc *busdma_bufalloc_t;
   57 
   58 /*
   59  * Create an allocator that manages a pool of DMA buffers.
   60  *
   61  * The allocator manages a collection of uma(9) zones of buffers in power-of-two
   62  * sized increments ranging from minimum_alignment to the platform's PAGE_SIZE.
   63  * The buffers within each zone are aligned on boundaries corresponding to the
   64  * buffer size, and thus by implication each buffer is contiguous within a page
   65  * and does not cross a power of two boundary larger than the buffer size.
   66  * These rules are intended to make it easy for a busdma implementation to
   67  * check whether a tag's constraints allow use of a buffer from the allocator.
   68  *
   69  * minimum_alignment is also the minimum buffer allocation size.  For platforms
   70  * with software-assisted cache coherency, this is typically the data cache line
   71  * size (and MUST not be smaller than the cache line size).
   72  *
   73  * name appears in zone stats as 'dma name nnnnn' where 'dma' is fixed and
   74  * 'nnnnn' is the size of buffers in that zone.
   75  *
   76  * If the alloc/free function pointers are NULL, the regular uma internal
   77  * allocators are used (I.E., you get "plain old kernel memory").  On a platform
   78  * with an exclusion zone that applies to all DMA operations, a custom allocator
   79  * could be used to ensure no buffer memory is ever allocated from that zone,
   80  * allowing the bus_dmamem_alloc() implementation to make the assumption that
   81  * buffers provided by the allocation could never lead to the need for a bounce.
   82  */
   83 busdma_bufalloc_t busdma_bufalloc_create(const char *name,
   84     bus_size_t minimum_alignment,
   85     uma_alloc uma_alloc_func, uma_free uma_free_func,
   86     u_int32_t uma_zcreate_flags);
   87 
   88 /*
   89  * Destroy an allocator created by busdma_bufalloc_create().
   90  * Safe to call with a NULL pointer.
   91  */
   92 void busdma_bufalloc_destroy(busdma_bufalloc_t ba);
   93 
   94 /*
   95  * Return a pointer to the busdma_bufzone that should be used to allocate or
   96  * free a buffer of the given size.  Returns NULL if the size is larger than the
   97  * largest zone handled by the allocator.
   98  */
   99 struct busdma_bufzone * busdma_bufalloc_findzone(busdma_bufalloc_t ba,
  100     bus_size_t size);
  101 
  102 /*
  103  * These built-in allocation routines are available for managing a pools of
  104  * uncacheable memory on platforms that support VM_MEMATTR_UNCACHEABLE.
  105  *
  106  * Allocation is done using kmem_alloc_attr() with these parameters:
  107  *   lowaddr  = 0
  108  *   highaddr = BUS_SPACE_MAXADDR
  109  *   memattr  = VM_MEMATTR_UNCACHEABLE.
  110  *
  111  * If your platform has no exclusion region (lowaddr/highaddr), and its pmap
  112  * routines support pmap_page_set_memattr() and the VM_MEMATTR_UNCACHEABLE flag
  113  * you can probably use these when you need uncacheable buffers.
  114  */
  115 void * busdma_bufalloc_alloc_uncacheable(uma_zone_t zone, vm_size_t size,
  116     int domain, uint8_t *pflag, int wait);
  117 void  busdma_bufalloc_free_uncacheable(void *item, vm_size_t size,
  118     uint8_t pflag);
  119 
  120 #endif  /* _MACHINE_BUSDMA_BUFALLOC_H_ */

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