From: Juergen Beisert <jbe@pengutronix.de>
To: barebox@lists.infradead.org
Subject: Re: serial_ns16550 driver question
Date: Thu, 21 Jul 2011 10:34:27 +0200 [thread overview]
Message-ID: <201107211034.27574.jbe@pengutronix.de> (raw)
In-Reply-To: <20110721062818.GU20587@pengutronix.de>
Sascha Hauer wrote:
> On Thu, Jul 21, 2011 at 05:12:24AM +0200, Jean-Christophe PLAGNIOL-VILLARD
wrote:
> > On 22:31 Wed 20 Jul , Sascha Hauer wrote:
> > > On Wed, Jul 20, 2011 at 11:51:04PM +0400, Antony Pavlov wrote:
> > > > Hi!
> > > >
> > > > In include/ns16550.h we have:
> > > >
> > > > struct NS16550_plat {
> > > > unsigned int clock;
> > > > unsigned char f_caps;
> > > > /**
> > > > * register read access capability
> > > > */
> > > > unsigned int (*reg_read) (unsigned long base, unsigned char
> > > > reg_offset); /**
> > > > * register write access capability
> > > > */
> > > > void (*reg_write) (unsigned int val, unsigned long base,
> > > > unsigned char reg_offset);
> > > > };
> > > >
> > > > Why reg_read and reg_write's argument base has type unsigned long?
> > > > IMHO pointer type (void * or char *) is more natural.
> > >
> > > You're right, I also wondered about this recently when looking at a
> > > patch on the list. I would also rather see void __iomem *. The problem
> > > is that this driver is also used on X86 which uses inb/outb which take
> > > an integer argument.
> > > The Linux driver works around this by having a membase and a iobase
> > > field along with different register accessors. While being cleaner
> > > I'm unsure if we want to go this way.
> >
> > we can do it via resoure and the flasgs IORESOURCE_MEM_8BIT,
> > IORESOURCE_MEM_168BITi etc..
>
> Yes, but this does not solve the problem with different accessor
> functions (and their argument type).
Why not adapt the x86 inb/outb function to the same arguments types than other
archs are using for their memory mapped access? We are in Barebox, not in the
kernel. I think we can do so, without damaging something in our _small_ x86
Barebox world.
jbe
--
Pengutronix e.K. | Juergen Beisert |
Linux Solutions for Science and Industry | Phone: +49-5121-206917-5128 |
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prev parent reply other threads:[~2011-07-21 8:35 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-07-20 19:51 Antony Pavlov
2011-07-20 20:31 ` Sascha Hauer
2011-07-21 3:12 ` Jean-Christophe PLAGNIOL-VILLARD
2011-07-21 6:28 ` Sascha Hauer
2011-07-21 8:34 ` Juergen Beisert [this message]
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