[PATCH] ARM: Gemini: Add support for PCI BUS
Arnd Bergmann
arnd at arndb.de
Mon Dec 6 07:18:24 EST 2010
On Monday 06 December 2010, Sergei Shtylyov wrote:
> > There are many differences between readl and __raw_readl, including
>
> > * __raw_readl does not have barriers and does not serialize with
> > spinlocks, so it breaks on out-of-order CPUs.
> > * __raw_readl does not have a specific endianess, while readl is
> > fixed little-endian,
>
> I know I'm late but readl()/writel() are CPU-endian, not LE.
If that was the case, it would be a bug. readl/writel is defined to be
the same endianess as PCI, which is little-endian. Otherwise you would
not be able to use any PCI devices on big-endian ARM machines. The
definition of readl is
#define readl(addr) __le32_to_cpu(__raw_readl(addr))
which converts the little-endian I/O register into a native endian
CPU register.
Arnd
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