Date: Wed, 10 Jan 2001 13:51:01 -0600 From: Jonathan Lemon <jlemon@flugsvamp.com> To: Peter Jeremy <peter.jeremy@alcatel.com.au> Cc: Brian Somers <brian@Awfulhak.org>, Sergey Babkin <babkin@FreeBSD.ORG>, freebsd-arch@FreeBSD.ORG Subject: Re: cvs commit: src/sys/gnu/i386/isa dgb.c dgm.c dgmreg.h dgreg.h Message-ID: <20010110135101.S29115@prism.flugsvamp.com> In-Reply-To: <20010111064126.A10214@pc0640.alcatel.com.au> References: <babkin@FreeBSD.org> <200101052146.f05LkDi49430@hak.lan.Awfulhak.org> <20010111064126.A10214@pc0640.alcatel.com.au>
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On Thu, Jan 11, 2001 at 06:41:26AM +1100, Peter Jeremy wrote:
> There are come significant differences between the [E]ISA aand PCI
> DigiBoards:
> - The [E]ISA cards use I/O ports whilst the PCI boards use
> memory-mapped registers.
> - The PCI cards have a flat 4MB window. The [E]ISA cards access
> on-board memory via a 8KB or 32KB window.
>
> This means that the code does a lot of checking to see if the card
> is PCI or not, resulting in expressions like:
> ((IS_PCI(board_type)) ? *mem[reg] : inb(base + reg))
This should be taken care of by the bus_space() macros; which is
already done by most drivers in the tree. (Many drivers can run
in either PIO or memory mapped mode)
> The Linux driver (maintained by Digi) uses (the equivalent of) virtual
> functions for all card accesses.
This is another option; the ida driver does something like this,
if I understand you correctly; it uses board-specific accessor
functions to hide hardware implementation details.
> Would it be reasonable to have different drivers for different bus
> versions of the same card?
I don't think this would be a good idea. We already have a framework
where the common code is kept in a foo.c file, and the bus-specific
code in foo_{pci|eisa}.c files, but the entire thing is wrapped up in
a single "foo" driver.
--
Jonathan
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