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.\" Copyright (c) 2016 Ruslan Bukin <br@bsdpad.com>
.\" All rights reserved.
.\"
.\" This software was developed by SRI International and the University of
.\" Cambridge Computer Laboratory under DARPA/AFRL contract FA8750-10-C-0237
.\" ("CTSRD"), as part of the DARPA CRASH research programme.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\" notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice, this list of conditions and the following disclaimer in the
.\" documentation and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\" $FreeBSD$
.\"
.Dd December 12, 2016
.Dt XDMA 4
.Os
.Sh NAME
.Nm xdma
.Nd DMA abstraction layer
.Sh SYNOPSIS
To compile xDMA device support into the kernel, place the following line
in your kernel configuration file:
.Bd -ragged -offset indent
.Cd "device xdma"
.Ed
.Pp
To compile xDMA FDT-based test driver, place the following line as well:
.Bd -literal -offset indent
.Cd "device xdma_test"
.Ed
.Sh DESCRIPTION
xDMA is a DMA framework designed to abstract the interaction between device
drivers and DMA engines.
.Pp
xDMA defines an interface for efficient interaction between the device driver
and DMA controller.
The
.Nm
device provides a virtual DMA controller and virtual channels called xchans.
The controller provides virtual channels management (allocation, deallocation,
configuration) and interrupt notification esteblishment needed to receive
events from the hardware DMA controller.
.Nm
supports the following transfer types:
.Bl -hang -offset indent -width xxxxxxxx
.It Nm Cyclic
A non-stop periodic transfer designed for applications like audio.
.It Nm Memcpy
A memory-to-memory transfer.
.El
.Sh SEE ALSO
.Xr bus_dma 9
.Sh HISTORY
Support for xDMA first appeared in
.Fx 12.0 .
.Sh AUTHORS
.An -nosplit
.Fx
xDMA framework was first added by
.An Ruslan Bukin Aq Mt br@FreeBSD.org .
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