[PATCH v2] ARM: asm: add readq/writeq methods

[Peter Maydell]

On 7 December 2013 16:05, Matthias Mann <M.Mann at arkona-technologies.de> wrote:
> Add readq/writeq methods for 32 bit ARM to allow transfering 64 bit words over
> PCIe as a single transfer.

> +#if __LINUX_ARM_ARCH__ >= 5
> +static inline u64 __raw_readq(const volatile void __iomem *addr)
> +{
> +       u64 val;
> +#if __LITTLE_ENDIAN
> +       asm volatile("ldrd %Q1, %R1, %0"
> +                    : "+Q" (*(volatile u64 __force *)addr),
> +                      "=r" (val));
> +#else
> +       asm volatile("ldrd %R1, %Q1, %0"
> +                    : "+Q" (*(volatile u64 __force *)addr),
> +                      "=r" (val));
> +#endif
> +       return val;
> +}

Given that ldrd/strd accesses are only a single 64 bit access
on CPUs with LPAE (on non-LPAE CPUs they may be
implemented as just a pair of 32 bit accesses) should the
condition be stricter than just __LINUX_ARM_ARCH__ >= 5 ?

thanks
-- PMM