From: Marcelo Tosatti <marcelo.tosatti@cyclades•com>
To: Benjamin Herrenschmidt <benh@kernel•crashing.org>
Cc: Paul Mackerras <paulus@samba•org>,
linux-ppc-embedded <linuxppc-embedded@ozlabs•org>
Subject: Re: [PATCH] add big endian version of ld_/st_ IO access macros and convert main 8xx code to use it
Date: Wed, 7 Sep 2005 21:51:35 -0300 [thread overview]
Message-ID: <20050908005135.GA8882@dmt.cnet> (raw)
In-Reply-To: <1126139332.29803.0.camel@gaston>
On Thu, Sep 08, 2005 at 10:28:52AM +1000, Benjamin Herrenschmidt wrote:
> On Wed, 2005-09-07 at 20:03 -0300, Marcelo Tosatti wrote:
> > Hi,
> >
> > The following patch adds big endian version of ld_/st_ macros
> > and converts core 8xx code to use them.
> >
> > Other than making IO accesses explicit (which is a plus for
> > readability), a common set of macros provides a unified place for the
> > volatile flag to constraint compiler code reordering.
> >
> > There are several unlucky places at the moment which lack the
> > volatile flag.
>
> I'm not fan of the approach. You should use in_/out_ macros for IOs. If
> you don't need eieio on 8xx , then just #ifdef it out of the
> implementation of these.
The reason for that is that in_/out_ are supposed to be the standard
IO macros (conformance)? In practice most drivers using the std macros
can benefit from the change.
A common routine is shared by all architectures. Doing something like
/*
* 8, 16 and 32 bit, big and little endian I/O operations, with barrier.
*/
extern inline int in_8(volatile unsigned char __iomem *addr)
{
int ret;
__asm__ __volatile__(
"lbz%U1%X1 %0,%1;\n"
#ifndef CONFIG_8xx
"twi 0,%0,0;\n"
"isync" : "=r" (ret) : "m" (*addr));
#else
: "=r" (ret) : "m" (*addr));
#endif
return ret;
}
Seems somewhat ugly?
next prev parent reply other threads:[~2005-09-08 0:56 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-09-07 23:03 [PATCH] add big endian version of ld_/st_ IO access macros and convert main 8xx code to use it Marcelo Tosatti
2005-09-08 0:28 ` Benjamin Herrenschmidt
2005-09-08 0:42 ` Dan Malek
2005-09-08 0:55 ` Benjamin Herrenschmidt
2005-09-08 0:58 ` Marcelo Tosatti
2005-09-08 4:27 ` Paul Mackerras
2005-09-08 13:56 ` Dan Malek
2005-09-08 19:34 ` Marcelo Tosatti
2005-09-08 0:51 ` Marcelo Tosatti [this message]
2005-09-08 1:14 ` Benjamin Herrenschmidt
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