[PATCH] ARM: Add atomic64 routines for ARMv6k and above.

[u.kleine-koenig@pengutronix.de (Uwe Kleine-König)]

Hello,

On Fri, Dec 11, 2009 at 06:13:57PM +0000, Will Deacon wrote:
> In preparation for perf-events support, ARM needs to support atomic64_t
> operations. v6k and above support the ldrexd and strexd instructions to do
> just that.
> 
> This patch adds atomic64 support to the ARM architecture. v6k and above
> make use of new instructions whilst older cores fall back on the generic
> solution using spinlocks. If and when v7-M cores are supported by Linux, they
> will need to fall back on the spinlock implementation too.
> 
> Signed-off-by: Will Deacon <will.deacon@arm.com>
> Acked-by: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Jamie Iles <jamie.iles@picochip.com>
> ---
>  arch/arm/Kconfig              |    1 +
>  arch/arm/include/asm/atomic.h |  228 +++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 229 insertions(+), 0 deletions(-)
> 
> diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
> index 1c4119c..5fdc032 100644
> --- a/arch/arm/Kconfig
> +++ b/arch/arm/Kconfig
> @@ -18,6 +18,7 @@ config ARM
>  	select HAVE_KRETPROBES if (HAVE_KPROBES)
>  	select HAVE_FUNCTION_TRACER if (!XIP_KERNEL)
>  	select HAVE_GENERIC_DMA_COHERENT
> +	select GENERIC_ATOMIC64 if (!CPU_32v6K)
If a kernel supports say a v5 and a v6 then IIRC CPU_32v6K is enabled,
but GENERIC_ATOMIC64 is needed, too.

Maybe I missed something.

Best regards
Uwe

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Pengutronix e.K.                              | Uwe Kleine-K?nig            |
Industrial Linux Solutions                    | http://www.pengutronix.de/  |