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<== Date ==> <== Thread ==>
Subject: Re: Using Asyn driver or modifying devLib (or related programs) of EPICSbase for any knid of cPCI cards
From: Andrew Johnson <[email protected]>
To: Jenny Chen <[email protected]>
Cc: [email protected]
Date: Mon, 08 Oct 2007 14:20:58 -0500
Jenny Chen wrote: 

We may have a cPCI crate with an Intel CPU and four DI/DO/AI/AO cards
soon. The OS might be Fedora Linux2.6. Before we write any Asyn
driver for EPICS, I think we need to know how to write/install the
driver and implement test programs for the cards.

It would certainly be wise to understand the hardware before writing an Asyn driver for it. However you should probably have at least some understanding of how an Asyn driver behaves before you finish the kernel driver for the hardware.

We purchase the cards locally (might be ADLink).

Make sure that you check out the Comedi website that Emmanual mentioned, their supported hardware mentions a number of ADLink boards for which drivers are available: http://www.comedi.org/hardware.html

Has anyone else written Asyn drivers for boards using Comedi?

We might also buy
some other cards later (might from other company). The Linux kernel 2.6 and 2.4 are quite different, right?

Correct, the internal Linux kernel APIs used by kernel drivers are significantly different between 2.4 and 2.6, and can change between different minor releases of 2.6 (2.6.23 is very different to 2.6.1).

The way to install driver for cPCI cards is similar or not?

A cPCI driver will be very similar to any other in-kernel PCI driver.

One more question, is it difficult to handle interrupt from cPCI
cards?

As Emmanuel has suggested you probably don't want to try and bring interrupt information all the way up to user-space â the various mechanisms available for signaling interrupts to user-space are significantly slower than handling the interrupt completely inside your kernel driver, but debugging code that runs in the kernel can be much harder than code running in user-space.

Hopefully the Comedi drivers will save you from having to write much code.

- Andrew
--
When a distinguished but elderly scientist states that something is
possible, he is almost certainly right.  When he states that something
is impossible, he is very probably wrong.  -- Arthur C. Clarke
References:
RE: Using Asyn driver or modifying devLib (or related programs) of EPICSbase for any knid of cPCI cards Jenny Chen
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