Create an architecture-agnostic buffer pool manager that uses uma(9) to
manage a set of power-of-2 sized buffers for bus_dmamem_alloc(). This allows the caller to provide the back-end allocator uma allocator, allowing full control of the memory pages backing the pool. For convenience, it provides an optional builtin allocator that provides pages allocated with the VM_MEMATTR_UNCACHEABLE attribute, for managing pools of DMA buffers for BUS_DMA_COHERENT or BUS_DMA_NOCACHE. This also allows the caller to specify a minimum alignment, and it ensures that all buffers start on a boundary and have a length that's a multiple of that value, to avoid using buffers that trigger partial cache line flushes. Submitted by: Ian Lepore <freebsd@damnhippie.dyndns.org>
This commit is contained in:
Olivier Houchard
parent
3254bef2ec
commit
05d9035003
174
sys/kern/subr_busdma_bufalloc.c
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174
sys/kern/subr_busdma_bufalloc.c
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@ -0,0 +1,174 @@
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/*-
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* Copyright (c) 2012 Ian Lepore
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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/*
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* Buffer allocation support routines for bus_dmamem_alloc implementations.
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*/
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/bus.h>
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#include <sys/busdma_bufalloc.h>
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#include <sys/malloc.h>
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#include <vm/vm.h>
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#include <vm/vm_extern.h>
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#include <vm/vm_kern.h>
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#include <vm/uma.h>
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/*
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* We manage buffer zones up to a page in size. Buffers larger than a page can
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* be managed by one of the kernel's page-oriented memory allocation routines as
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* efficiently as what we can do here. Also, a page is the largest size for
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* which we can g'tee contiguity when using uma, and contiguity is one of the
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* requirements we have to fulfill.
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*/
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#define MIN_ZONE_BUFSIZE 32
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#define MAX_ZONE_BUFSIZE PAGE_SIZE
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/*
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* The static array of 12 bufzones is big enough to handle all the zones for the
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* smallest supported allocation size of 32 through the largest supported page
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* size of 64K. If you up the biggest page size number, up the array size too.
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* Basically the size of the array needs to be log2(maxsize)-log2(minsize)+1,
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* but I don't know of an easy way to express that as a compile-time constant.
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*/
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#if PAGE_SIZE > 65536
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#error Unsupported page size
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#endif
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struct busdma_bufalloc {
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bus_size_t min_size;
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size_t num_zones;
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struct busdma_bufzone buf_zones[12];
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};
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busdma_bufalloc_t
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busdma_bufalloc_create(const char *name, bus_size_t minimum_alignment,
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uma_alloc alloc_func, uma_free free_func, u_int32_t zcreate_flags)
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{
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struct busdma_bufalloc *ba;
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struct busdma_bufzone *bz;
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int i;
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bus_size_t cursize;
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ba = malloc(sizeof(struct busdma_bufalloc), M_DEVBUF,
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M_ZERO | M_WAITOK);
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ba->min_size = MAX(MIN_ZONE_BUFSIZE, minimum_alignment);
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/*
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* Each uma zone is created with an alignment of size-1, meaning that
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* the alignment is equal to the size (I.E., 64 byte buffers are aligned
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* to 64 byte boundaries, etc). This allows for a fast efficient test
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* when deciding whether a pool buffer meets the constraints of a given
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* tag used for allocation: the buffer is usable if tag->alignment <=
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* bufzone->size.
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*/
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for (i = 0, bz = ba->buf_zones, cursize = ba->min_size;
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i < nitems(ba->buf_zones) && cursize <= MAX_ZONE_BUFSIZE;
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++i, ++bz, cursize <<= 1) {
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snprintf(bz->name, sizeof(bz->name), "dma %.10s %lu",
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name, cursize);
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bz->size = cursize;
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bz->umazone = uma_zcreate(bz->name, bz->size,
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NULL, NULL, NULL, NULL, bz->size - 1, zcreate_flags);
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if (bz->umazone == NULL) {
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busdma_bufalloc_destroy(ba);
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return (NULL);
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}
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if (alloc_func != NULL)
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uma_zone_set_allocf(bz->umazone, alloc_func);
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if (free_func != NULL)
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uma_zone_set_freef(bz->umazone, free_func);
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++ba->num_zones;
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}
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return (ba);
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}
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void
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busdma_bufalloc_destroy(busdma_bufalloc_t ba)
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{
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struct busdma_bufzone *bz;
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int i;
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if (ba == NULL)
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return;
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for (i = 0, bz = ba->buf_zones; i < ba->num_zones; ++i, ++bz) {
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uma_zdestroy(bz->umazone);
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}
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free(ba, M_DEVBUF);
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}
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struct busdma_bufzone *
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busdma_bufalloc_findzone(busdma_bufalloc_t ba, bus_size_t size)
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{
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struct busdma_bufzone *bz;
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int i;
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if (size > MAX_ZONE_BUFSIZE)
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return (NULL);
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for (i = 0, bz = ba->buf_zones; i < ba->num_zones; ++i, ++bz) {
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if (bz->size >= size)
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return (bz);
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}
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panic("Didn't find a buffer zone of the right size");
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}
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void *
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busdma_bufalloc_alloc_uncacheable(uma_zone_t zone, int size, u_int8_t *pflag,
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int wait)
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{
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#ifdef VM_MEMATTR_UNCACHEABLE
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/* Inform UMA that this allocator uses kernel_map/object. */
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*pflag = UMA_SLAB_KERNEL;
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return ((void *)kmem_alloc_attr(kernel_map, size, wait, 0,
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BUS_SPACE_MAXADDR, VM_MEMATTR_UNCACHEABLE));
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#else
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panic("VM_MEMATTR_UNCACHEABLE unavailable");
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#endif /* VM_MEMATTR_UNCACHEABLE */
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}
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void
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busdma_bufalloc_free_uncacheable(void *item, int size, u_int8_t pflag)
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{
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kmem_free(kernel_map, (vm_offset_t)item, size);
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}
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118
sys/sys/busdma_bufalloc.h
Normal file
118
sys/sys/busdma_bufalloc.h
Normal file
@ -0,0 +1,118 @@
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/*-
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* Copyright (c) 2012 Ian Lepore
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
|
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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/*
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* $FreeBSD$
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*/
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/*
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* A buffer pool manager, for use by a platform's busdma implementation.
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*/
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#ifndef _MACHINE_BUSDMA_BUFALLOC_H_
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#define _MACHINE_BUSDMA_BUFALLOC_H_
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#include <machine/bus.h>
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#include <vm/uma.h>
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/*
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* Information about a buffer zone, returned by busdma_bufalloc_findzone().
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*/
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struct busdma_bufzone {
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bus_size_t size;
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uma_zone_t umazone;
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char name[24];
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};
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/*
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* Opaque handle type returned by busdma_bufalloc_create().
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*/
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struct busdma_bufalloc;
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typedef struct busdma_bufalloc *busdma_bufalloc_t;
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/*
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* Create an allocator that manages a pool of DMA buffers.
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*
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* The allocator manages a collection of uma(9) zones of buffers in power-of-two
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* sized increments ranging from minimum_alignment to the platform's PAGE_SIZE.
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* The buffers within each zone are aligned on boundaries corresponding to the
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* buffer size, and thus by implication each buffer is contiguous within a page
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* and does not cross a power of two boundary larger than the buffer size.
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* These rules are intended to make it easy for a busdma implementation to
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* check whether a tag's constraints allow use of a buffer from the allocator.
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*
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* minimum_alignment is also the minimum buffer allocation size. For platforms
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* with software-assisted cache coherency, this is typically the data cache line
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* size (and MUST not be smaller than the cache line size).
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*
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* name appears in zone stats as 'dma name nnnnn' where 'dma' is fixed and
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* 'nnnnn' is the size of buffers in that zone.
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*
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* If if the alloc/free function pointers are NULL, the regular uma internal
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* allocators are used (I.E., you get "plain old kernel memory"). On a platform
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* with an exclusion zone that applies to all DMA operations, a custom allocator
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* could be used to ensure no buffer memory is ever allocated from that zone,
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* allowing the bus_dmamem_alloc() implementation to make the assumption that
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* buffers provided by the allocation could never lead to the need for a bounce.
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*/
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busdma_bufalloc_t busdma_bufalloc_create(const char *name,
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bus_size_t minimum_alignment,
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uma_alloc uma_alloc_func, uma_free uma_free_func,
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u_int32_t uma_zcreate_flags);
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/*
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* Destroy an allocator created by busdma_bufalloc_create().
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* Safe to call with a NULL pointer.
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*/
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void busdma_bufalloc_destroy(busdma_bufalloc_t ba);
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/*
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* Return a pointer to the busdma_bufzone that should be used to allocate or
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* free a buffer of the given size. Returns NULL if the size is larger than the
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* largest zone handled by the allocator.
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*/
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struct busdma_bufzone * busdma_bufalloc_findzone(busdma_bufalloc_t ba,
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bus_size_t size);
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/*
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* These built-in allocation routines are available for managing a pools of
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* uncacheable memory on platforms that support VM_MEMATTR_UNCACHEABLE.
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*
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* Allocation is done using kmem_alloc_attr() with these parameters:
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* lowaddr = 0
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* highaddr = BUS_SPACE_MAXADDR
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* memattr = VM_MEMATTR_UNCACHEABLE.
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*
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* If your platform has no exclusion region (lowaddr/highaddr), and its pmap
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* routines support pmap_page_set_memattr() and the VM_MEMATTR_UNCACHEABLE flag
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* you can probably use these when you need uncacheable buffers.
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*/
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void * busdma_bufalloc_alloc_uncacheable(uma_zone_t zone, int size,
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u_int8_t *pflag, int wait);
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void busdma_bufalloc_free_uncacheable(void *item, int size, u_int8_t pflag);
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#endif /* _MACHINE_BUSDMA_BUFALLOC_H_ */
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