Re: [PATCH] ARM: supplementing IO accessors with 64 bit capability

[Catalin Marinas]

On Wed, Oct 22, 2014 at 05:06:23PM +0100, mathieu.poirier@xxxxxxxxxx wrote:
> +#if __LINUX_ARM_ARCH__ >= 5

My old ARMv5 book does not list LDRD/STRD. It looks like they only come
with ARMv5TE. Are there any processors prior to this supported by the
kernel?

> +static inline void __raw_writeq(u64 val, volatile void __iomem *addr)
> +{
> +	asm volatile("strd %1, %0"
> +		     : "+Qo" (*(volatile u64 __force *)addr)
> +		     : "r" (val));
> +}
> +
> +static inline u64 __raw_readq(const volatile void __iomem *addr)
> +{
> +	u64 val;
> +	asm volatile("ldrd %1, %0"
> +		     : "+Qo" (*(volatile u64 __force *)addr),
> +		       "=r" (val));
> +	return val;
> +}
> +#endif

I'm curious why you need these. Do you have a device that needs a 64-bit
single access or you are trying to read two consecutive registers?

-- 
Catalin
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