Date: Mon, 08 Sep 1997 14:05:39 +1000 From: Mike Smith <mike@smith.net.au> To: =?iso-8859-1?Q?=DEor=F0ur?= Ivarsson <totii@est.is> Cc: hackers@FreeBSD.ORG Subject: Re: How do I write device driver Message-ID: <199709080405.OAA01269@word.smith.net.au> In-Reply-To: Your message of "Thu, 04 Sep 1997 15:30:51 GMT." <340ED42B.41C67EA6@est.is>
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> Can any of you help me with writing device driver for two cards i have > here on my desk. > I have all documents and API information for the cards. > > One is AD converter 8input 12bit + 1 DA 12bit > > and the other is digital IO card with 6 8bit ports and timer IO based > on two 8255 and one 8253 > > I heard of something like /dev/IO but I did not find any information > about writing interface to it. You don't have to do much for this; just open /dev/io and use the macros in <machine/cpufunc.h>, specifically the in* and out* family. The first question you should ask is : do you need a device driver? If you don't need to handle DMA or interrupts or have strict timing requirements, user-mode I/O using the /dev/io technique can be very effective. We have a data interface capable of >1MB/sec that we talk to exclusively with this method. mike
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