lkml.org 
[lkml]   [2011]   [Feb]   [26]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
SubjectRE: [PATCH 09/12] unicore32 machine related files: hardware registers
Date


> -----Original Message-----
> From: Arnd Bergmann [mailto:arnd@arndb.de]
> Sent: Saturday, February 26, 2011 9:16 PM
> To: Guan Xuetao
> Cc: linux-kernel@vger.kernel.org; linux-arch@vger.kernel.org; 'Greg KH'
> Subject: Re: [PATCH 09/12] unicore32 machine related files: hardware registers
>
> On Saturday 26 February 2011, Guan Xuetao wrote:
> > > > #ifndef __ASSEMBLY__
> > > >
> > > > -# define __REG(x) (*((volatile unsigned long *)io_p2v(x)))
> > > > -# define __PREG(x) (io_v2p((unsigned long)&(x)))
> > > > +# define __REG(x) (void __iomem *)io_p2v(x)
> > >
> > > The patch looks correct, but if you make the the definition for
> > > PKUNITY_MMIO_BASE contain the cast to (void __iomem *), you no
> > > longer need another cast.
> >
> > Because the io_p2v(x) calculate x and PKUNITY_IOSPACE_BASE,
> > all registers should be added with (void __iomem *).
> > So I prefer to remain the previous patch.
>
> The problem with the definition of io_p2v is that it gives you
> an type that is impossible to use correctly, except in assembly
> code. Linux assumes that MMIO registers in virtual space
> are __iomem pointers, and we like that to be consistent.
>
> If you have a function that returns a virtual address, it should
> really have the same type as any other function that uses a virtual
> address.
Ok, I see.
Please see following patch, __REG removed and __iomem added to io_p2v:

diff --git a/arch/unicore32/include/mach/hardware.h b/arch/unicore32/include/mach/hardware.h
index b71405a..b197b0b 100644
--- a/arch/unicore32/include/mach/hardware.h
+++ b/arch/unicore32/include/mach/hardware.h
@@ -17,13 +17,10 @@

#include "PKUnity.h"

-#define io_p2v(x) ((x) - PKUNITY_MMIO_BASE)
-#define io_v2p(x) ((x) + PKUNITY_MMIO_BASE)
-
#ifndef __ASSEMBLY__
-
-# define __REG(x) (void __iomem *)io_p2v(x)
-
+#define io_p2v(x) (void __iomem *)((x) - PKUNITY_MMIO_BASE)
+#else
+#define io_p2v(x) ((x) - PKUNITY_MMIO_BASE)
#endif

#define PCIBIOS_MIN_IO 0x4000 /* should lower than 64KB */
> Arnd
Thanks & Regards.
Guan Xuetao



\
 
 \ /
  Last update: 2011-02-27 04:37    [W:0.072 / U:0.660 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site