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Date:      Thu, 8 Oct 1998 13:36:19 +0100 (MET)
From:      Luigi Rizzo <luigi@labinfo.iet.unipi.it>
To:        lile@stdio.com (Larry S. Lile)
Cc:        hackers@FreeBSD.ORG
Subject:   Re: DMA questions
Message-ID:  <199810081236.NAA10560@labinfo.iet.unipi.it>
In-Reply-To: <Pine.SUN.3.91.981008093527.20081B-100000@heathers.stdio.com> from "Larry S. Lile" at Oct 8, 98 09:45:31 am

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> I am working on a driver for Olicom token-ring cards and using the
> Linux driver as a guideline but I am unsure about the dma commands
> they are using.  Any ideas on how to replicate this under FreeBSD?
> 
> Also is 
> there any good reference for dma under FreeBSD I can't seem to find much?

UTSL i am afraid... sys/i386/isa/isa.c is about all you have :(

> >   clear_dma_ff(dmachan);           <  This is what I am confused 
> >   set_dma_count (dmachan, 0);      <  about...
> >   set_dma_mode (dmachan, 0xc0);    <
> >   enable_dma (dmachan);            <

these seem to be directly mapped to actions you can do on the DMA
registers. I think isa_dmastart() and friends do most if not all you
need. You have to figure out if the above sets the dma in single or
auto mode, that's all. A good reference on the various ISA peripheral
is at www.intel.com as part of the PIIX controller data sheets (i82371
if i am not mistaken). This chip includes most ISA peripherals (serial,
parallel, IDE, timer, DMA, interrupt controllers...).

	cheers
	luigi
-----------------------------+--------------------------------------
Luigi Rizzo                  |  Dip. di Ingegneria dell'Informazione
email: luigi@iet.unipi.it    |  Universita' di Pisa
tel: +39-50-568533           |  via Diotisalvi 2, 56126 PISA (Italy)
fax: +39-50-568522           |  http://www.iet.unipi.it/~luigi/
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