From owner-freebsd-hackers  Tue Jul 20 13:39:57 1999
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From: Wilko Bulte <wilko@yedi.iaf.nl>
Message-Id: <199907202037.WAA00801@yedi.iaf.nl>
Subject: Re: any docs on how to use bus_dma_tag_create e.a. ?
In-Reply-To: <199907201958.NAA07710@narnia.plutotech.com> from "Justin T. Gibbs" at "Jul 20, 1999  1:58:54 pm"
To: gibbs@narnia.plutotech.com (Justin T. Gibbs)
Date: Tue, 20 Jul 1999 22:37:47 +0200 (CEST)
Cc: hackers@FreeBSD.ORG
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As Justin T. Gibbs wrote ...
> In article <199907201904.VAA03203@yedi.iaf.nl> you wrote:
> > I'm currently trying to hack a driver together for a PCI card that uses
> > shared memory to communicate to the host.
> > 
> > If I'm not completely offtrack I need to use (under newbus/-current)
> > bus_dma_tag_create, bus_dma_alloc etc to get access to the cards shared
> > memory.
> 
> bus_dma related stuff is only required if the device has a DMA engine
> you wish to use.  To access the shared memory on the card (e.g. map

Eh, sorry, I was confused. It has *both* shared memory and a DMA engine.

> it into the kernel's virtual address space), you will need to use
> the resource manager and bus space.

Do you by chance have an example (maybe in -current somewhere) of the
shared memory stuff? I found some DMA stuff in ahc_pci.c:

 /* Allocate a dmatag for our SCB DMA maps */
        /* XXX Should be a child of the PCI bus dma tag */
        error = bus_dma_tag_create(/*parent*/NULL, /*alignment*/0,
                                   /*boundary*/0,
                                   /*lowaddr*/BUS_SPACE_MAXADDR_32BIT,
                                   /*highaddr*/BUS_SPACE_MAXADDR,
                                   /*filter*/NULL, /*filterarg*/NULL,
                                   /*maxsize*/MAXBSIZE,
				   /*nsegments*/AHC_NSEG,
                                   /*maxsegsz*/AHC_MAXTRANSFER_SIZE,
                                   /*flags*/BUS_DMA_ALLOCNO

but I admit it is not too clear (yet..) what all the parameters do.

Most (?) drivers seem to use the older framework (can I distinguish
those by COMPAT_PCI_DRIVER() ?).

Thanks,
	Wilko
-- 
|   / o / /  _  	 Arnhem, The Netherlands	- Powered by FreeBSD -
|/|/ / / /( (_) Bulte 	 WWW  : http://www.tcja.nl 	http://www.freebsd.org


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