From owner-freebsd-arch  Wed Jan 10 15:26:32 2001
Delivered-To: freebsd-arch@freebsd.org
Received: from mobile.wemm.org (c1315225-a.plstn1.sfba.home.com [65.0.135.147])
	by hub.freebsd.org (Postfix) with ESMTP
	id CC7C637B69F; Wed, 10 Jan 2001 15:26:14 -0800 (PST)
Received: from netplex.com.au (localhost [127.0.0.1])
	by mobile.wemm.org (8.11.1/8.11.1) with ESMTP id f0ANNcQ63145;
	Wed, 10 Jan 2001 15:23:39 -0800 (PST)
	(envelope-from peter@netplex.com.au)
Message-Id: <200101102323.f0ANNcQ63145@mobile.wemm.org>
X-Mailer: exmh version 2.2 06/23/2000 with nmh-1.0.4
To: Jonathan Lemon <jlemon@flugsvamp.com>
Cc: Peter Jeremy <peter.jeremy@alcatel.com.au>,
	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 
In-Reply-To: <20010110135101.S29115@prism.flugsvamp.com> 
Date: Wed, 10 Jan 2001 15:23:38 -0800
From: Peter Wemm <peter@netplex.com.au>
Sender: owner-freebsd-arch@FreeBSD.ORG
Precedence: bulk
X-Loop: FreeBSD.ORG

Jonathan Lemon wrote:
> 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)

But the bus_space_() stuff doesn't handle changing register windows etc.
eg: if you have a 64K memory space and can read/write it directly when
memory mapped, but when on ISA it is all crammed into 16 lots of 4K windows
then bus_space_() cannot save you from this.

ie:
  if (IS_PCI(board_type)) {
	value = *mem[reg];
  } else {
        if (board->window != window(reg))
	   board->window = window(reg);
	value = inb(base + (reg % winsize));
  }

Cheers,
-Peter
--
Peter Wemm - peter@FreeBSD.org; peter@yahoo-inc.com; peter@netplex.com.au
"All of this is for nothing if we don't go to the stars" - JMS/B5



To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-arch" in the body of the message